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Dai X, Liang R, Dai M, Li X, Zhao W. Smoking Impacts Alzheimer's Disease Progression Through Oral Microbiota Modulation. Mol Neurobiol 2025; 62:19-44. [PMID: 38795302 DOI: 10.1007/s12035-024-04241-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Accepted: 05/13/2024] [Indexed: 05/27/2024]
Abstract
Alzheimer's disease (AD) is an important public health challenge with a limited understanding of its pathogenesis. Smoking is a significant modifiable risk factor for AD progression, and its specific mechanism is often interpreted from a toxicological perspective. However, microbial infections also contribute to AD, with oral microbiota playing a crucial role in its progression. Notably, smoking alters the ecological structure and pathogenicity of the oral microbiota. Currently, there is no systematic review or summary of the relationship between these three factors; thus, understanding this association can help in the development of new treatments. This review summarizes the connections between smoking, AD, and oral microbiota from existing research. It also explores how smoking affects the occurrence and development of AD through oral microbiota, and examines treatments for oral microbiota that delay the progression of AD. Furthermore, this review emphasizes the potential of the oral microbiota to act as a biomarker for AD. Finally, it considers the feasibility of probiotics and oral antibacterial therapy to expand treatment methods for AD.
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Affiliation(s)
- Xingzhu Dai
- Department of Stomatology, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, China
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Rui Liang
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Manqiong Dai
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Xiaoyu Li
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Wanghong Zhao
- Department of Stomatology, Nanfang Hospital, Southern Medical University, Guangzhou, China.
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Zhang P, Liu Y, Jin X, Hu Z, Yang J, Lu H, Hang T, Song M. Alzheimer's disease-like pathology induced by Porphyromonas gingivalis in middle-aged mice is mediated by NLRP3 inflammasome via the microbiota-gut-brain axis. J Alzheimers Dis 2024:13872877241302498. [PMID: 39639573 DOI: 10.1177/13872877241302498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2024]
Abstract
BACKGROUND Porphyromonas gingivalis (P. gingivalis) has been found to enter the brain and induce inflammation, contributing to Alzheimer's disease (AD). P. gingivalis is also closely linked to gut dysbiosis. However, does P. gingivalis induce AD-like pathology through the microbiota-gut-brain axis? There is limited literature on this topic. OBJECTIVE To determine the precise causal link among P. gingivalis, intestinal inflammation, and AD-related pathology. METHODS 12- to 13-month-old female C57BL/6J mice were subjected to ligature placement and oral administration of P. gingivalis over a 24-week period. Then, cognitive performance was evaluated with behavioral tests, while AD neuropathological changes, neuroinflammation, and intestinal inflammation were assessed through qPCR, immunofluorescence, and western blot, and gut microbiota was analyzed by 16S rRNA. RESULTS Mice exposed to P. gingivalis showed impaired behavior in open field test, novel object recognition, and Y-maze tests. The bacterium infiltrated their brains, increasing Aβ42, AβPP, and Aβ fragments, promoting tau phosphorylation and microglial activation, and reducing levels of ZO-1, PSD95, SYP, and NeuN proteins. Inflammatory factors like NLRP3, caspase-1, IL-1β, IL-6, and TNF-α were elevated in both brains and intestine, while ZO-1 and occludin levels decreased in intestine. P. gingivalis also altered gut microbial compositions. CONCLUSIONS P. gingivalis induced gut dysbiosis and activated the NLRP3 inflammasome in the intestine and brains of mice. This led to impairment of both the intestinal and brain-blood barriers, triggering neuroinflammation and promoting the progression of AD. These findings highlight the critical role of NLRP3 inflammasome activation in the microbiota-gut-brain axis in the AD-like pathology induced by P. gingivalis.
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Affiliation(s)
- Pei Zhang
- Key Laboratory of Drug Quality Control and Pharmacovigilance (China Pharmaceutical University), Ministry of Education, Nanjing, China
- Department of Pharmaceutical Analysis, China Pharmaceutical University, Nanjing, China
| | - Yan Liu
- Key Laboratory of Drug Quality Control and Pharmacovigilance (China Pharmaceutical University), Ministry of Education, Nanjing, China
- Department of Pharmaceutical Analysis, China Pharmaceutical University, Nanjing, China
| | - Xin Jin
- Key Laboratory of Drug Quality Control and Pharmacovigilance (China Pharmaceutical University), Ministry of Education, Nanjing, China
- Department of Pharmaceutical Analysis, China Pharmaceutical University, Nanjing, China
| | - Zhaoliang Hu
- Key Laboratory of Drug Quality Control and Pharmacovigilance (China Pharmaceutical University), Ministry of Education, Nanjing, China
- Department of Pharmaceutical Analysis, China Pharmaceutical University, Nanjing, China
| | - Jucui Yang
- Key Laboratory of Drug Quality Control and Pharmacovigilance (China Pharmaceutical University), Ministry of Education, Nanjing, China
- Department of Pharmaceutical Analysis, China Pharmaceutical University, Nanjing, China
| | - Haotian Lu
- International Department of High School, AFF to Nanjing Normal University Jiangning Campus, Nanjing, China
| | - Taijun Hang
- Key Laboratory of Drug Quality Control and Pharmacovigilance (China Pharmaceutical University), Ministry of Education, Nanjing, China
- Department of Pharmaceutical Analysis, China Pharmaceutical University, Nanjing, China
| | - Min Song
- Key Laboratory of Drug Quality Control and Pharmacovigilance (China Pharmaceutical University), Ministry of Education, Nanjing, China
- Department of Pharmaceutical Analysis, China Pharmaceutical University, Nanjing, China
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Cao T, Tian D, Wang S, Pan Y, Xia Z, Chen W, Yang S, Zeng Q, Zhao Y, Zheng L, Li N, Lai Z, Luo Y, Shen Z. Microglial DBP Signaling Mediates Behavioral Abnormality Induced by Chronic Periodontitis in Mice. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2406269. [PMID: 39429161 PMCID: PMC11633467 DOI: 10.1002/advs.202406269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Revised: 10/10/2024] [Indexed: 10/22/2024]
Abstract
Several lines of evidence implicate that chronic periodontitis (CP) increases the risk of mental illnesses, such as anxiety and depression, yet, the associated molecular mechanism for this remains poorly defined. Here, it is reported that mice subjected to CP exhibited depression-like behaviors and hippocampal memory deficits, accompanied by synapse loss and neurogenesis impairment in the hippocampus. RNA microarray analysis disclosed that albumin D-site-binding protein (DBP) is identified as the most prominently upregulated target gene following CP, and in vivo and in vitro immunofluorescence methods showed that DBP is preferentially expressed in microglia but not neurons or astrocytes in the hippocampus. Interestingly, it is found that the expression of DBP is significantly increased in microglia after CP, and knockdown of microglial DBP ameliorated the behavioral abnormality, as well as reversed the synapse loss and hippocampal neurogenesis damage induced by CP. Furthermore, DBP knockdown improved the CP-induced hippocampal inflammation and microglial polarization. Collectively, these results indicate a critical role of DBP in orchestrating chronic periodontitis-related behavioral abnormality, hippocampal synapse loss and neurogenesis deficits, in which the microglial activation may be indispensably involved.
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Affiliation(s)
- Ting Cao
- Department of Children's StomatologyStomatological Hospital of Xiamen Medical College, Xiamen Key Laboratory of Stomatological Disease Diagnosis and TreatmentXiamen361003China
| | - Dan Tian
- Department of PharmacologySchool of PharmacyFujian Medical UniversityFuzhou350122China
| | - Si‐Ying Wang
- Department of PharmacologySchool of PharmacyFujian Medical UniversityFuzhou350122China
| | - Yue Pan
- Department of PharmacologySchool of PharmacyFujian Medical UniversityFuzhou350122China
| | - Zhi‐Xuan Xia
- Department of Pharmacology, School of Basic Medicine and Life ScienceHainan Medical UniversityHaikou571199China
| | - Wei‐Kai Chen
- Department of PharmacologySchool of PharmacyFujian Medical UniversityFuzhou350122China
| | - Shao‐Wei Yang
- Department of PharmacologySchool of PharmacyFujian Medical UniversityFuzhou350122China
| | - Qing‐Quan Zeng
- Department of PharmacologySchool of PharmacyFujian Medical UniversityFuzhou350122China
| | - Yue‐Ling Zhao
- Department of PharmacologySchool of PharmacyFujian Medical UniversityFuzhou350122China
| | - Ling Zheng
- Department of PharmacologySchool of PharmacyFujian Medical UniversityFuzhou350122China
| | - Ning Li
- Fujian Key Laboratory of Drug Target Discovery and Structural and Functional Research, School of PharmacyFujian Medical UniversityFuzhou350122China
| | - Zhong‐Meng Lai
- Department of AnesthesiologyUnion Hospital, Fujian Medical UniversityFuzhou350001China
| | - Yi‐Xiao Luo
- Hunan Province People's HospitalThe First‐affiliated Hospital of Hunan Normal UniversityChangsha410002China
| | - Zu‐Cheng Shen
- Department of PharmacologySchool of PharmacyFujian Medical UniversityFuzhou350122China
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Kazemi N, Khorasgani MR, Noorbakhshnia M, Razavi SM, Narimani T, Naghsh N. Protective effects of a lactobacilli mixture against Alzheimer's disease-like pathology triggered by Porphyromonas gingivalis. Sci Rep 2024; 14:27283. [PMID: 39516514 PMCID: PMC11549306 DOI: 10.1038/s41598-024-77853-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 10/25/2024] [Indexed: 11/16/2024] Open
Abstract
Porphyromonas gingivalis (P. gingivalis) is one of the pathogens involved in gingival inflammation, which may trigger neuroinflammatory diseases such as Alzheimer's disease (AD). This study aimed to investigate the protective (preventive and treatment) effects of a lactobacilli mixture combining Lactobacillus reuteri PTCC1655, Lactobacillus brevis CD0817, Lacticaseibacillus rhamnosus PTCC1637, and Lactobacillus plantarum PTCC1058 against P. gingivalis-induced gingival inflammation and AD-like pathology in rats. These probiotic strains exhibited cognitive enhancement effects, but this study proposed to assess their activity in a mixture. To propose a probable mechanism for P. gingivalis cognitive impairments, the TEs balance were analyzed in hippocampus and cortex tissues. Animals were divided into five groups: the control, lactobacilli, P. gingivalis, lactobacilli + P. gingivalis (prevention), and P. gingivalis + lactobacilli group (treatment) groups. The behavioral and histopathological changes were compared among them. Finally, The Trace elements (TEs) levels in the hippocampus and cortex tissues were analyzed. The palatal tissue sections of the P. gingivalis infected rats showed moderate inflammation with dense infiltration of inflammatory cells, a limited area of tissue edema, and vascular congestion. Additionally, passive avoidance learning and spatial memory were impaired. Histopathological tests revealed the presence of Aβ-positive cells in the P. gingivalis group. While the Aβ-positive cells decreased in the treatment group, their formation was inhibited in the preventive group. Administration of a mixture of lactobacilli (orally) effectively mitigated the gingival inflammation, Aβ production, and improved learning and memory functions. Moreover, Zn, Cu, and Mn levels in the hippocampus were dramatically elevated by P. gingivalis infection, whereas lactobacilli mixture mitigated these disruptive effects. The lactobacilli mixture significantly prevented the disruptive effects of P. gingivalis on gingival and brain tissues in rats. Therefore, new formulated combination of lactobacilli may be a good candidate for inhibiting the P. gingivalis infection and its subsequent cognitive effects. The current study aimed to evaluate the effects of a lactobacilli mixture to manage the disruptive effects of P. gingivalis infection on memory.
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Affiliation(s)
- Niloofar Kazemi
- Department of Cell and Molecular Biology and Microbiology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, Iran
| | - Mohammad Rabbani Khorasgani
- Department of Cell and Molecular Biology and Microbiology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, Iran.
| | - Maryam Noorbakhshnia
- Department of Plant and Animal Biology, Faculty of Biological Science and Technology, University of Isfahan, Isfahan, Iran.
| | - Seyed Mohammad Razavi
- Department of Oral and Maxillofacial Pathology, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Tahmineh Narimani
- Department of Bacteriology and Virology, Faculty of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Narges Naghsh
- Department of Periodontology, Torabinejad Dental Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
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Cafferata EA, Ramanauskaite A, Cuypers A, Obreja K, Dohle E, Ghanaati S, Schwarz F. Experimental peri-implantitis induces neuroinflammation: An exploratory study in rats. BMC Oral Health 2024; 24:1238. [PMID: 39425138 PMCID: PMC11490110 DOI: 10.1186/s12903-024-04995-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2024] [Accepted: 10/01/2024] [Indexed: 10/21/2024] Open
Abstract
PURPOSE Cumulating evidence supports the close association between periodontal diseases, neuroinflammation and neurodegenerative pathologies, except for peri-implantitis (PI). Thus, this study explored the association between experimental PI and neuropathological changes in the rat brain. MATERIALS AND METHODS After bilateral first molars extraction, experimental PI was induced at titanium implants placed in the maxillae by lipopolysaccharide injections and ligature placement. Following 28-weeks of disease progression, the maxillae and brains were retrieved from 6 rats. Healthy brains from 3 rats were used as control. Brains were analyzed by immunohistochemistry to detect signs of neuroinflammation (interleukin (IL)-6 and tumor necrosis factor (TNF)-α)), microglial activation (IBA-1) and astrogliosis (GFAP). To explore signs of neurodegeneration, hematoxylin/eosin and Nissl stainings were used. Also, four different antibodies against amyloid beta (Aβ 1-42) were tested. RESULTS Chronic PI lesions showed peri-implant bone resorption accompanied by large inflammatory infiltrates. IL-6+ and TNF-α+ cells were found within the CA1 and Dentate Gyrus regions of the hippocampus of the PI-affected group, while almost no immune-positivity was detected in the control (p < 0.05). Detection of activated GFAP+ microglia and IBA-1+ astrocytes surface were significantly higher at the CA areas, and cerebral cortex of the PI-affected group, in comparison with control (p < 0.05). Shrunk neurons with pyknotic nuclei were inconsistently found among the PI-affected group, and these were almost not detected in control. No positive Aβ reactivity was detected in any of the samples. CONCLUSION Chronic experimental PI lesions led to an increased detection of IL-6 and TNF-α, GFAP+ microgliosis and IBA-1+ astrocytosis, and in some cases, neurodegeneration, in the rat brain.
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Affiliation(s)
- Emilio A Cafferata
- Department of Oral Surgery and Implantology, Goethe University, Carolinum, Frankfurt am Main, Germany.
- Department of Periodontology, School of Dentistry, Universidad Científica del Sur, Lima, Perú.
| | - Ausra Ramanauskaite
- Department of Oral Surgery and Implantology, Goethe University, Carolinum, Frankfurt am Main, Germany
| | - Astrid Cuypers
- Department of Oral Surgery and Implantology, Goethe University, Carolinum, Frankfurt am Main, Germany
| | - Karina Obreja
- Department of Oral Surgery and Implantology, Goethe University, Carolinum, Frankfurt am Main, Germany
| | - Eva Dohle
- Frankfurt Oral Regenerative Medicine (FORM-Lab), Clinic for Maxillofacial and Plastic Surgery, Goethe University, Frankfurt am Main, Germany
| | - Shahram Ghanaati
- Frankfurt Oral Regenerative Medicine (FORM-Lab), Clinic for Maxillofacial and Plastic Surgery, Goethe University, Frankfurt am Main, Germany
| | - Frank Schwarz
- Department of Oral Surgery and Implantology, Goethe University, Carolinum, Frankfurt am Main, Germany
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Qian X, Lin X, Hu W, Zhang L, Chen W, Zhang S, Ge S, Xu X, Luo K. Intestinal homeostasis disrupted by Periodontitis exacerbates Alzheimer's Disease in APP/PS1 mice. J Neuroinflammation 2024; 21:263. [PMID: 39425119 PMCID: PMC11489998 DOI: 10.1186/s12974-024-03256-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2024] [Accepted: 10/07/2024] [Indexed: 10/21/2024] Open
Abstract
Periodontitis exacerbates Alzheimer's disease (AD) through multiple pathways. Both periodontitis and AD are intricately correlated to intestinal homeostasis, yet there is still a lack of direct evidence regarding whether periodontitis can regulate the progression of AD by modulating intestinal homeostasis. The current study induced experimental periodontitis in AD mice by bilaterally ligating the maxillary second molars with silk and administering Pg-LPS injections in APPswe/PS1ΔE9 (APP/PS1) mice. Behavioral tests and histological analyses of brain tissue were conducted after 8 weeks. Gut microbiota was analyzed and colon tissue were also evaluated. Then, fecal microbiota from mice with periodontitis was transplanted into antibiotic-treated mice to confirm the effects of periodontitis on AD and the potential mechanism was explored. The results indicated periodontitis exacerbated cognitive impairment and anxious behaviour in APP/PS1 mice, with increased Aβ deposition, microglial overactivation and neuroinflammation in brain. Moreover, the intestinal homeostasis of AD mice was altered by periodontitis, including affecting gut microbiota composition, causing colon inflammation and destroyed intestinal epithelial barrier. Furthermore, AD mice that underwent fecal transplantation from mice with periodontitis exhibited worsened AD progression and disrupted intestinal homeostasis. It also impaired intestinal barrier function, elevated peripheral inflammation, damaged blood-brain barrier (BBB) and caused neuroinflammation and synapses impairment. Taken together, the current study demonstrated that periodontitis could disrupt intestinal homeostasis to exacerbate AD progression potential via causing gut microbial dysbiosis, intestinal inflammation and intestinal barrier impairment to induce peripheral inflammation and damage BBB, ultimately leading to neuroinflammation and synapse impairment. It underscores the importance of maintaining both periodontal health and intestinal homeostasis to reduce the risk of AD.
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Affiliation(s)
- Xueshen Qian
- Fujian Key Laboratory of Oral Diseases & Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key laboratory of Fujian College and University, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, P.R. China
- Institute of Stomatology & Laboratory of Oral Tissue Engineering, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, 350002, P.R. China
| | - Xuxin Lin
- Fujian Key Laboratory of Oral Diseases & Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key laboratory of Fujian College and University, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, P.R. China
- Institute of Stomatology & Laboratory of Oral Tissue Engineering, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, 350002, P.R. China
| | - Weiqiang Hu
- Fujian Key Laboratory of Oral Diseases & Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key laboratory of Fujian College and University, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, P.R. China
- Institute of Stomatology & Laboratory of Oral Tissue Engineering, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, 350002, P.R. China
| | - Lu Zhang
- Fujian Key Laboratory of Oral Diseases & Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key laboratory of Fujian College and University, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, P.R. China
- Institute of Stomatology & Laboratory of Oral Tissue Engineering, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, 350002, P.R. China
| | - Wenqian Chen
- Fujian Key Laboratory of Oral Diseases & Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key laboratory of Fujian College and University, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, P.R. China
- Institute of Stomatology & Laboratory of Oral Tissue Engineering, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, 350002, P.R. China
| | - Shuang Zhang
- Nanjing Stomatological Hospital, Affiliated Hospital of Medical School, Institute of Stomatology, Nanjing University, Nanjing, Jiangsu, 210008, P.R. China
| | - Song Ge
- School and Hospital of Stomatology, Zunyi Medical University, Zunyi, Guizhou, 563003, P.R. China
| | - Xiongcheng Xu
- Fujian Key Laboratory of Oral Diseases & Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key laboratory of Fujian College and University, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, P.R. China.
- Institute of Stomatology & Laboratory of Oral Tissue Engineering, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, 350002, P.R. China.
| | - Kai Luo
- Fujian Key Laboratory of Oral Diseases & Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key laboratory of Fujian College and University, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, P.R. China.
- Institute of Stomatology & Laboratory of Oral Tissue Engineering, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, 350002, P.R. China.
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Min JH, Sarlus H, Harris RA. MAD-microbial (origin of) Alzheimer's disease hypothesis: from infection and the antimicrobial response to disruption of key copper-based systems. Front Neurosci 2024; 18:1467333. [PMID: 39416952 PMCID: PMC11480022 DOI: 10.3389/fnins.2024.1467333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2024] [Accepted: 09/20/2024] [Indexed: 10/19/2024] Open
Abstract
Microbes have been suspected to cause Alzheimer's disease since at least 1908, but this has generally remained unpopular in comparison to the amyloid hypothesis and the dominance of Aβ and Tau. However, evidence has been accumulating to suggest that these earlier theories are but a manifestation of a common cause that can trigger and interact with all the major molecular players recognized in AD. Aβ, Tau and ApoE, in particular appear to be molecules with normal homeostatic functions but also with alternative antimicrobial functions. Their alternative functions confer the non-immune specialized neuron with some innate intracellular defenses that appear to be re-appropriated from their normal functions in times of need. Indeed, signs of infection of the neurons by biofilm-forming microbial colonies, in synergy with herpes viruses, are evident from the clinical and preclinical studies we discuss. Furthermore, we attempt to provide a mechanistic understanding of the AD landscape by discussing the antimicrobial effect of Aβ, Tau and ApoE and Lactoferrin in AD, and a possible mechanistic link with deficiency of vital copper-based systems. In particular, we focus on mitochondrial oxidative respiration via complex 4 and ceruloplasmin for iron homeostasis, and how this is similar and possibly central to neurodegenerative diseases in general. In the case of AD, we provide evidence for the microbial Alzheimer's disease (MAD) theory, namely that AD could in fact be caused by a long-term microbial exposure or even long-term infection of the neurons themselves that results in a costly prolonged antimicrobial response that disrupts copper-based systems that govern neurotransmission, iron homeostasis and respiration. Finally, we discuss potential treatment modalities based on this holistic understanding of AD that incorporates the many separate and seemingly conflicting theories. If the MAD theory is correct, then the reduction of microbial exposure through use of broad antimicrobial and anti-inflammatory treatments could potentially alleviate AD although this requires further clinical investigation.
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Affiliation(s)
- Jin-Hong Min
- Department of Clinical Neuroscience, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital at Solna, Stockholm, Sweden
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Uçan Yarkaç F, Babayiğit O, Gokturk O. Associations between immune-inflammatory markers, age, and periodontal status: a cross-sectional study. Odontology 2024; 112:1296-1306. [PMID: 38443702 DOI: 10.1007/s10266-024-00907-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 01/29/2024] [Indexed: 03/07/2024]
Abstract
Since periodontal disease is associated with many systemic diseases, it is important to evaluate its effects on host responses in elderly individuals. To this end, this study investigated salivary interleukin (IL)-17, IL-18, toll-like receptor (TLR) 2, TLR4, and tumor necrosis factor-alpha (TNF-α) levels in patient groups with different periodontal health statuses and immunologically evaluated the relationship between age and periodontal health status. A total of 60 individuals aged 18-40 years (young individuals) and 60 individuals aged 65 years or older (elderly individuals) were included in this study. According to periodontal disease status, the patients were divided into periodontally healthy, gingivitis, and periodontitis subgroups. Clinical periodontal parameters, including probing depth (PD), clinical attachment level (CAL), plaque index (PI), and gingival index (GI), were recorded. Saliva samples were collected and analyzed using ELISA to determine the levels of IL-17, IL-18, TLR2, TLR4, and TNF-α. Higher clinical periodontal parameter (PD, CAL, PI, and GI) and inflammatory marker (IL-17, IL-18, TNF-α, TLR2, and TLR4) levels were found in patients with periodontitis than those in periodontally healthy individuals and patients with gingivitis (P < 0.05). Salivary inflammatory marker levels were significantly higher in elderly individuals than those in young individuals in all subgroups (P < 0.05). A positive correlation was found between inflammatory marker levels and clinical periodontal parameters, but there was no correlation between TLR2 and PI or GI. This study suggests a significant increase in host response to periodontal disease as the disease progresses, with the levels of cytokines and TLR expression exhibiting an increasing trend with age. Increased IL-17, IL-18, TLR2, TLR4, and TNF-α levels in elderly individuals in all periodontal health subgroups might suggest the role of these cytokines and TLR pathway in the pathogenesis of periodontal diseases.
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Affiliation(s)
- Fatma Uçan Yarkaç
- Department of Periodontology, Necmettin Erbakan University Faculty of Dentistry, Konya, Turkey
| | - Osman Babayiğit
- Department of Periodontology, Necmettin Erbakan University Faculty of Dentistry, Konya, Turkey.
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9
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Drakes N, Kondrikova G, Pytel D, Hamlett ED. Unveiling the Intricate Link Between Anaerobe Niche and Alzheimer Disease Pathogenesis. J Infect Dis 2024; 230:S117-S127. [PMID: 39255391 DOI: 10.1093/infdis/jiae312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2024] Open
Abstract
Dysbiosis within microbiomes has been increasingly implicated in many systemic illnesses, such as cardiovascular disease, metabolic syndrome, respiratory infections, and Alzheimer disease (Ad). The correlation between Ad and microbial dysbiosis has been repeatedly shown, yet the etiologic cause of microbial dysbiosis remains elusive. From a neuropathology perspective, abnormal (often age-related) changes in the brain, associated structures, and bodily lumens tend toward an accumulation of oxygen-depleted pathologic structures, which are anaerobically selective niches. These anaerobic environments may promote progressive change in the microbial community proximal to the brain and thus deserve further investigation. In this review, we identify and explore what is known about the anaerobic niche near or associated with the brain and the anaerobes that it is harbors. We identify the anaerobe stakeholders within microbiome communities and the impacts on the neurodegenerative processes associated with Ad. Chronic oral dysbiosis in anaerobic dental pockets and the composition of the gut microbiota from fecal stool are the 2 largest anaerobic niche sources of bacterial transference to the brain. At the blood-brain barrier, cerebral atherosclerotic plaques are predominated by anaerobic species intimately associated with the brain vasculature. Focal cerebritis/brain abscess and corpora amylacea may also establish chronic anaerobic niches in direct proximity to brain parenchyma. In exploring the anaerobic niche proximal to the brain, we identify research opportunities to explore potential sources of microbial dysbiosis associated with Ad.
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Affiliation(s)
- NyEmma Drakes
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina
- Department of Biology, College of Charleston
| | - Galina Kondrikova
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina
- Department of Veterans Affairs, Ralph H. Johnson VA Medical Center, Charleston, South Carolina
| | - Dariusz Pytel
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina
- Department of Clinical Chemistry and Biochemistry, Medical University of Lodz, Poland
| | - Eric D Hamlett
- Department of Pathology and Laboratory Medicine, Medical University of South Carolina
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Li X, Yao C, Lan D, Chen Y, Wang Y, Qi S. Porphyromonas gingivalis promote microglia M1 polarization through the NF-кB signaling pathway. Heliyon 2024; 10:e35340. [PMID: 39170188 PMCID: PMC11336649 DOI: 10.1016/j.heliyon.2024.e35340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Revised: 06/24/2024] [Accepted: 07/26/2024] [Indexed: 08/23/2024] Open
Abstract
Background Porphyromonas gingivalis (P.gingivalis) is associated with the onset of Alzheimer's disease (AD), but the underlying molecular mechanism is unclear. Neuroinflammation in the brain from the microglial immune response induces the pathological progression of AD. In this study, the roles and molecular mechanism of P.gingivalis in microglial inflammation in vitro were investigated. Methods In this study, a P.gingivalis oral administration mouse model was generated, and microglia were stimulated with P.gingivalis in vitro. The viability of the microglia after P.gingivalis treatment was evaluated through CCK-8 and live/dead cell staining. Inflammation in brain tissue after P.gingivalis treatment and the immune response of microglia in vitro were detected by RT‒PCR, Western blotting and IF. Moreover, the RNA sequence was used, and the role of the NF-κB signalling pathway in microglial activation was analysed after P.gingivalis stimulation. Results The mRNA and protein levels of IL-6 and IL-17 were increased, and the expression of IL-10 was decreased in brain tissue after P.gingivalis oral administration. The viability of the HMC3 cells significantly decreased with 5% P.gingivalis after stimulation. The results of live/dead cell staining also showed the inhibitory effect of 5% P.gingivalis supplementation on cell viability. Moreover, 5% P.gingivalis supplementation increased the mRNA and protein levels of IL-6 and IL-17 and decreased IL-10 expression in HMC3 cells. P.gingivalis supplementation increased the mRNA and protein levels of iNOS and CD86 and decreased CD206 expression in HMC3 cells. RNA sequencing revealed that the NF-κB signalling pathway was involved in this process. Furthermore, p-P65 was upregulated and p-IKBα was downregulated in brain tissue and HMC3 cells after P.gingivalis stimulation, and an NF-κB signalling pathway inhibitor (QNZ) reversed the viability, M1 polarization and inflammatory factors of microglia in HMC3 cells in vitro. Conclusions In conclusion, P.gingivalis induced neuroinflammation in the brain, possibly through promotion of M1 polarization of microglia via activation of the NF-κB signalling pathway during the progression of AD.
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Affiliation(s)
- Xue Li
- Department of Oral Prosthodontics, Shanghai Stomatological Hospital, Fudan University, Shanghai, 200001, China
- Shanghai Key Laboratory of Craniomaxillofacial Development and Diseases, Fudan University, Shanghai, 200002, China
- Medical College, Anhui University of Science and Technology, Huainan, 232001, China
| | - Chao Yao
- Shanghai Key Laboratory of Craniomaxillofacial Development and Diseases, Fudan University, Shanghai, 200002, China
| | - Dongmei Lan
- Shanghai Key Laboratory of Craniomaxillofacial Development and Diseases, Fudan University, Shanghai, 200002, China
| | - Yurong Chen
- Department of Oral Prosthodontics, Shanghai Stomatological Hospital, Fudan University, Shanghai, 200001, China
- Shanghai Key Laboratory of Craniomaxillofacial Development and Diseases, Fudan University, Shanghai, 200002, China
- Medical College, Anhui University of Science and Technology, Huainan, 232001, China
| | - Yan Wang
- Shanghai Key Laboratory of Craniomaxillofacial Development and Diseases, Fudan University, Shanghai, 200002, China
- Medical College, Anhui University of Science and Technology, Huainan, 232001, China
- Department of Preventive Dentistry, Shanghai Stomatological Hospital, Fudan University, Shanghai, 200000, China
| | - Shengcai Qi
- Department of Oral Prosthodontics, Shanghai Stomatological Hospital, Fudan University, Shanghai, 200001, China
- Shanghai Key Laboratory of Craniomaxillofacial Development and Diseases, Fudan University, Shanghai, 200002, China
- Medical College, Anhui University of Science and Technology, Huainan, 232001, China
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11
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Tao K, Yuan Y, Xie Q, Dong Z. Relationship between human oral microbiome dysbiosis and neuropsychiatric diseases: An updated overview. Behav Brain Res 2024; 471:115111. [PMID: 38871130 DOI: 10.1016/j.bbr.2024.115111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Revised: 05/24/2024] [Accepted: 06/10/2024] [Indexed: 06/15/2024]
Abstract
The role of the gut-brain axis in mental health disorders has been extensively studied. As the oral cavity is the starting point of the digestive tract, the role that the oral microbiota plays in mental health disorders has gained recent attention. Oral microbiota can enter the bloodstream and trigger inflammatory responses or translocate to the brain through the trigeminal nerve or olfactory system. Hence, the concept of the oral microbiota-brain axis has emerged. Several hypotheses have been suggested that the oral microbiota can enter the gastrointestinal tract and affect the gut-brain axis; however, literature describing oral-brain communication remains limited. This review summarizes the characteristics of oral microbiota and its mechanisms associated with mental health disorders. Through a comprehensive examination of the relationship between oral microbiota and various neuropsychiatric diseases, such as anxiety, depression, schizophrenia, autism spectrum disorder, epilepsy, Parkinson's disease, and dementia, this review seeks to identify promising avenues of future research.
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Affiliation(s)
- Kai Tao
- West China School of Medicine, West China Hospital, Sichuan University, Chengdu 610041, People's Republic of China
| | - Yanling Yuan
- Department of Pharmacy, West China Hospital, Sichuan University, Chengdu 610041, People's Republic of China
| | - Qinglian Xie
- Department of Outpatient, West China Hospital, Sichuan University, Chengdu 610041, People's Republic of China; Department of Outpatient, West China Xiamen Hospital, Sichuan University, Fujian 361022, People's Republic of China.
| | - Zaiquan Dong
- Mental Health Center, West China Hospital, Sichuan University, Chengdu 610041, People's Republic of China.
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12
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Li F, Ma C, Lei S, Pan Y, Lin L, Pan C, Li Q, Geng F, Min D, Tang X. Gingipains may be one of the key virulence factors of Porphyromonas gingivalis to impair cognition and enhance blood-brain barrier permeability: An animal study. J Clin Periodontol 2024; 51:818-839. [PMID: 38414291 DOI: 10.1111/jcpe.13966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 01/24/2024] [Accepted: 02/08/2024] [Indexed: 02/29/2024]
Abstract
AIM Blood-brain barrier (BBB) disorder is one of the early findings in cognitive impairments. We have recently found that Porphyromonas gingivalis bacteraemia can cause cognitive impairment and increased BBB permeability. This study aimed to find out the possible key virulence factors of P. gingivalis contributing to the pathological process. MATERIALS AND METHODS C57/BL6 mice were infected with P. gingivalis or gingipains or P. gingivalis lipopolysaccharide (P. gingivalis LPS group) by tail vein injection for 8 weeks. The cognitive behaviour changes in mice, the histopathological changes in the hippocampus and cerebral cortex, the alternations of BBB permeability, and the changes in Mfsd2a and Cav-1 levels were measured. The mechanisms of Ddx3x-induced regulation on Mfsd2a by arginine-specific gingipain A (RgpA) in BMECs were explored. RESULTS P. gingivalis and gingipains significantly promoted mice cognitive impairment, pathological changes in the hippocampus and cerebral cortex, increased BBB permeability, inhibited Mfsd2a expression and up-regulated Cav-1 expression. After RgpA stimulation, the permeability of the BBB model in vitro increased, and the Ddx3x/Mfsd2a/Cav-1 regulatory axis was activated. CONCLUSIONS Gingipains may be one of the key virulence factors of P. gingivalis to impair cognition and enhance BBB permeability by the Ddx3x/Mfsd2a/Cav-1 axis.
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Affiliation(s)
- Fulong Li
- Department of Periodontics, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
- Center of Implantology, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
| | - Chunliang Ma
- Department of Periodontics, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
| | - Shuang Lei
- Department of Pediatric Dentistry, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
| | - Yaping Pan
- Department of Periodontics, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
| | - Li Lin
- Department of Periodontics, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
| | - Chunling Pan
- Department of Periodontics, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
| | - Qian Li
- Department of Periodontics, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
| | - Fengxue Geng
- Department of Periodontics, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
| | - Dongyu Min
- Traditional Chinese Medicine Experimental Center, Affiliated Hospital of Liaoning University of Traditional Chinese Medicine, Shenyang, China
- Key Laboratory of Ministry of Education for TCM Viscera State Theory and Applications, Liaoning University of Traditional Chinese Medicine, Shenyang, China
| | - Xiaolin Tang
- Department of Periodontics, School and Hospital of Stomatology, Liaoning Provincial Key Laboratory of Oral Disease, China Medical University, Shenyang, China
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13
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Chuang WC, Yang CN, Wang HW, Lin SK, Yu CC, Syu JH, Chiang CP, Shiao YJ, Chen YW. The mechanisms of Porphyromonas gingivalis-derived outer membrane vesicles-induced neurotoxicity and microglia activation. J Dent Sci 2024; 19:1434-1442. [PMID: 39035337 PMCID: PMC11259672 DOI: 10.1016/j.jds.2024.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Indexed: 07/23/2024] Open
Abstract
Background/purpose Periodontitis is associated with various systemic diseases, potentially facilitated by the passage of Porphyromonas gingivalis outer membrane vesicles (Pg-OMVs). Several recent studies have suggested a connection between Pg-OMVs and neuroinflammation and neurodegeneration, but the precise causal relationship remains unclear. This study aimed to investigate the mechanisms underlying these associations using in vitro models. Materials and methods Isolated Pg-OMVs were characterized by morphology, size, and gingipain activity. We exposed SH-SY5Y neuroblastoma cells and BV-2 microglial cells to various concentrations of Pg-OMVs. Cell morphology, a 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, an enzyme-linked immunosorbent assay, and Western blot analysis were used to evaluate the cellular mechanism underlying Pg-OMV-induced neurotoxicity in neuronal cells and inflammatory responses in microglial cells. Results Exposure to Pg-OMVs induced neurotoxicity in SH-SY5Y cells, as evidenced by cellular shrinkage, reduced viability, activation of apoptotic pathways, and diminished neuronal differentiation markers. Gingipain inhibition mitigated these effects, suggesting that gingipain mediates Pg-OMVs-induced neurotoxicity in SH-SY5Y cells. Our research on neuroinflammation suggests that upon endocytosis of Pg-OMVs by BV-2 cells, lipopolysaccharide (LPS) can modulate the production of inducible nitric oxide synthase and tumor necrosis factor-alpha by activating pathways that involve phosphorylated AKT and the phosphorylated JNK pathway. Conclusion Our study demonstrated that following the endocytosis of Pg-OMVs, gingipain can induce neurotoxicity in SH-SY5Y cells. Furthermore, the Pg-OMVs-associated LPS can trigger neuroinflammation via AKT and JNK signaling pathways in BV-2 cells.
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Affiliation(s)
- Wei-Chun Chuang
- Department of Dentistry, Fu Jen Catholic University Hospital, New Taipei City, Taiwan
| | - Cheng-Ning Yang
- Department of Dentistry, School of Dentistry, National Taiwan University, Taipei, Taiwan
| | - Han-Wei Wang
- Department of Dentistry, National Taiwan University Hospital, Taipei, Taiwan
| | - Sze-Kwan Lin
- Department of Dentistry, School of Dentistry, National Taiwan University, Taipei, Taiwan
- Department of Dentistry, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Ching-Chu Yu
- Graduate Institute of Oral Biology, School of Dentistry, National Taiwan University, Taipei, Taiwan
| | - Jhe-Hao Syu
- Graduate Institute of Oral Biology, School of Dentistry, National Taiwan University, Taipei, Taiwan
| | - Chun-Pin Chiang
- Department of Dentistry, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan
- Graduate Institute of Oral Biology, School of Dentistry, National Taiwan University, Taipei, Taiwan
- Graduate Institute of Clinical Dentistry, School of Dentistry, National Taiwan University, Taipei, Taiwan
- Department of Dentistry, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan
| | - Young-Ji Shiao
- National Research Institute of Chinese Medicine, Ministry of Health and Welfare, Taipei, Taiwan
| | - Yi-Wen Chen
- Department of Dentistry, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan
- Graduate Institute of Clinical Dentistry, School of Dentistry, National Taiwan University, Taipei, Taiwan
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14
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Kettunen P, Koistinaho J, Rolova T. Contribution of CNS and extra-CNS infections to neurodegeneration: a narrative review. J Neuroinflammation 2024; 21:152. [PMID: 38845026 PMCID: PMC11157808 DOI: 10.1186/s12974-024-03139-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Accepted: 05/23/2024] [Indexed: 06/09/2024] Open
Abstract
Central nervous system infections have been suggested as a possible cause for neurodegenerative diseases, particularly sporadic cases. They trigger neuroinflammation which is considered integrally involved in neurodegenerative processes. In this review, we will look at data linking a variety of viral, bacterial, fungal, and protozoan infections to Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis and unspecified dementia. This narrative review aims to bring together a broad range of data currently supporting the involvement of central nervous system infections in the development of neurodegenerative diseases. The idea that no single pathogen or pathogen group is responsible for neurodegenerative diseases will be discussed. Instead, we suggest that a wide range of susceptibility factors may make individuals differentially vulnerable to different infectious pathogens and subsequent pathologies.
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Affiliation(s)
- Pinja Kettunen
- Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Jari Koistinaho
- Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland.
| | - Taisia Rolova
- Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
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15
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Wang SY, Cai Y, Hu X, Li F, Qian XH, Xia LY, Gao B, Wu L, Xie WZ, Gu JM, Deng T, Zhu C, Jia HC, Peng WQ, Huang J, Fang C, Zeng XT. P. gingivalis in oral-prostate axis exacerbates benign prostatic hyperplasia via IL-6/IL-6R pathway. Mil Med Res 2024; 11:30. [PMID: 38764065 PMCID: PMC11103868 DOI: 10.1186/s40779-024-00533-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 04/30/2024] [Indexed: 05/21/2024] Open
Abstract
BACKGROUND Benign prostatic hyperplasia (BPH) is the most common disease in elderly men. There is increasing evidence that periodontitis increases the risk of BPH, but the specific mechanism remains unclear. This study aimed to explore the role and mechanism of the key periodontal pathogen Porphyromonas gingivalis (P. gingivalis) in the development of BPH. METHODS The subgingival plaque (Sp) and prostatic fluid (Pf) of patients with BPH concurrent periodontitis were extracted and cultured for 16S rDNA sequencing. Ligature-induced periodontitis, testosterone-induced BPH and the composite models in rats were established. The P. gingivalis and its toxic factor P. gingivalis lipopolysaccharide (P.g-LPS) were injected into the ventral lobe of prostate in rats to simulate its colonization of prostate. P.g-LPS was used to construct the prostate cell infection model for mechanism exploration. RESULTS P. gingivalis, Streptococcus oralis, Capnocytophaga ochracea and other oral pathogens were simultaneously detected in the Pf and Sp of patients with BPH concurrent periodontitis, and the average relative abundance of P. gingivalis was found to be the highest. P. gingivalis was detected in both Pf and Sp in 62.5% of patients. Simultaneous periodontitis and BPH synergistically aggravated prostate histological changes. P. gingivalis and P.g-LPS infection could induce obvious hyperplasia of the prostate epithelium and stroma (epithelial thickness was 2.97- and 3.08-fold that of control group, respectively), and increase of collagen fibrosis (3.81- and 5.02-fold that of control group, respectively). P. gingivalis infection promoted prostate cell proliferation, inhibited apoptosis, and upregulated the expression of inflammatory cytokines interleukin-6 (IL-6; 4.47-fold), interleukin-6 receptor-α (IL-6Rα; 5.74-fold) and glycoprotein 130 (gp130; 4.47-fold) in prostatic tissue. P.g-LPS could significantly inhibit cell apoptosis, promote mitosis and proliferation of cells. P.g-LPS activates the Akt pathway through IL-6/IL-6Rα/gp130 complex, which destroys the imbalance between proliferation and apoptosis of prostate cells, induces BPH. CONCLUSION P. gingivalis was abundant in the Pf of patients with BPH concurrent periodontitis. P. gingivalis infection can promote BPH, which may affect the progression of BPH via inflammation and the Akt signaling pathway.
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Affiliation(s)
- Shuang-Ying Wang
- Center for Evidence-Based and Translational Medicine, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
| | - Yi Cai
- Center for Evidence-Based and Translational Medicine, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
| | - Xiao Hu
- Center for Evidence-Based and Translational Medicine, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
| | - Fei Li
- Center for Evidence-Based and Translational Medicine, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
| | - Xin-Hang Qian
- Center for Evidence-Based and Translational Medicine, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
- Department of Urology, Huaihe Hospital of Henan University, Kaifeng, 475000, Henan, China
| | - Ling-Yun Xia
- Department of Stomatology, Taihe Hospital, Hubei University of Medicine, Shiyan, 442000, Hubei, China
| | - Bo Gao
- Department of Laboratory Medicine, Taihe Hospital, Hubei University of Medicine, Shiyan, 442000, Hubei, China
| | - Lan Wu
- Department of Stomatology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
| | - Wen-Zhong Xie
- Henan Provincial Engineering Research Center for Microecological Regulatory of Oral Environment and Oral Implantology, Kaifeng University Health Science Center, Kaifeng, 475000, Henan, China
| | - Jia-Min Gu
- Center for Evidence-Based and Translational Medicine, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
| | - Tong Deng
- Center for Evidence-Based and Translational Medicine, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
| | - Cong Zhu
- Center for Evidence-Based and Translational Medicine, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
| | - Hai-Chang Jia
- Center for Evidence-Based and Translational Medicine, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
| | - Wan-Qi Peng
- Department of Stomatology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
- School of Stomatology, Jinan University, Guangzhou, 510632, China
| | - Jiao Huang
- Center for Evidence-Based and Translational Medicine, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China.
| | - Cheng Fang
- Center for Evidence-Based and Translational Medicine, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China.
| | - Xian-Tao Zeng
- Center for Evidence-Based and Translational Medicine, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China.
- Department of Urology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China.
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Shen H, Jiang Y, Qiu C, Xie X, Zhang H, He Z, Song Z, Zhou W. Abnormal amyloid precursor protein processing in periodontal tissue in a murine model of periodontitis induced by Porphyromonas gingivalis. J Periodontal Res 2024; 59:395-407. [PMID: 38311599 DOI: 10.1111/jre.13224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 11/27/2023] [Accepted: 12/05/2023] [Indexed: 02/06/2024]
Abstract
OBJECTIVE The study aimed to investigate the change of amyloid precursor protein (APP) processing and amyloid β (Aβ) metabolites in linking periodontitis to Alzheimer's disease (AD). BACKGROUND Aβ is one of the main pathological features of AD, and few studies have discussed changes in its expression in peripheral tissues or analyzed the relationship between the peripheral imbalance of Aβ production and clearance. METHODS A murine model of periodontitis was established by oral infection with Porphyromonas gingivalis (P. gingivalis). Micro-computed tomography (Micro-CT) was used to observe the destruction of the alveolar bone. Nested quantitative polymerase chain reaction (qPCR) was used to measure small quantities of P.gingivalis DNA in different tissues. Behavioral experiments were performed to measure cognitive function in the mice. The mRNA levels of TNF-α, IL-6, IL-8, RANKL, OPG, APP695, APP751, APP770, and BACE1 in the gingival tissues or cortex were detected by RT-PCR. The levels of Aβ1-40 and Aβ1-42 in gingival crevicular fluid (GCF) and plasma were tested by ELISA. RESULTS P. gingivalis oral infection was found to cause alveolar bone resorption and impaired learning and memory. P.gingivalis DNA was detected in the gingiva, blood and cortex of the P.gingivalis group by nested qPCR (p < .05). The mRNA expression of TNF-α, IL-6, IL-8, RANKL/OPG, and BACE1 in the gingival tissue was significantly higher than that in the control group (p < .05). Similarly, upregulated mRNA levels of APP695 and APP770 were observed in the gingival tissuses and cortex of the P. gingivalis group (p < .05). The levels of Aβ1-40 and Aβ1-42 in the GCF and plasma of the P. gingivalis group were significantly higher than those in the control group (p < .05). CONCLUSION P. gingivalis can directly invade the brain via hematogenous infection. The invasion of P. gingivalis could trigger an immune response and lead to an imbalance between Aβ production and clearance in peripheral tissues, which may trigger an abnormal Aβ metabolite in the brain, resulting in the occurrence and development of AD.
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Affiliation(s)
- Hui Shen
- Department of Periodontology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
- National Center for Stomatology, National Clinical Research Center for Oral Diseases, Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Yiting Jiang
- Department of Periodontology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
- National Center for Stomatology, National Clinical Research Center for Oral Diseases, Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Che Qiu
- Department of Periodontology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
- National Center for Stomatology, National Clinical Research Center for Oral Diseases, Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Xinyi Xie
- Department of Periodontology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
- National Center for Stomatology, National Clinical Research Center for Oral Diseases, Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Huanyu Zhang
- Department of Periodontology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
- National Center for Stomatology, National Clinical Research Center for Oral Diseases, Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Zhiyan He
- National Center for Stomatology, National Clinical Research Center for Oral Diseases, Shanghai Key Laboratory of Stomatology, Shanghai, China
- Laboratory of Oral Microbiota and Systemic Diseases, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
| | - Zhongchen Song
- Department of Periodontology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
- National Center for Stomatology, National Clinical Research Center for Oral Diseases, Shanghai Key Laboratory of Stomatology, Shanghai, China
| | - Wei Zhou
- National Center for Stomatology, National Clinical Research Center for Oral Diseases, Shanghai Key Laboratory of Stomatology, Shanghai, China
- Laboratory of Oral Microbiota and Systemic Diseases, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, College of Stomatology, Shanghai Jiao Tong University, Shanghai, China
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17
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Brown GC, Heneka MT. The endotoxin hypothesis of Alzheimer's disease. Mol Neurodegener 2024; 19:30. [PMID: 38561809 PMCID: PMC10983749 DOI: 10.1186/s13024-024-00722-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 03/18/2024] [Indexed: 04/04/2024] Open
Abstract
Lipopolysaccharide (LPS) constitutes much of the surface of Gram-negative bacteria, and if LPS enters the human body or brain can induce inflammation and act as an endotoxin. We outline the hypothesis here that LPS may contribute to the pathophysiology of Alzheimer's disease (AD) via peripheral infections or gut dysfunction elevating LPS levels in blood and brain, which promotes: amyloid pathology, tau pathology and microglial activation, contributing to the neurodegeneration of AD. The evidence supporting this hypothesis includes: i) blood and brain levels of LPS are elevated in AD patients, ii) AD risk factors increase LPS levels or response, iii) LPS induces Aβ expression, aggregation, inflammation and neurotoxicity, iv) LPS induces TAU phosphorylation, aggregation and spreading, v) LPS induces microglial priming, activation and neurotoxicity, and vi) blood LPS induces loss of synapses, neurons and memory in AD mouse models, and cognitive dysfunction in humans. However, to test the hypothesis, it is necessary to test whether reducing blood LPS reduces AD risk or progression. If the LPS endotoxin hypothesis is correct, then treatments might include: reducing infections, changing gut microbiome, reducing leaky gut, decreasing blood LPS, or blocking LPS response.
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Affiliation(s)
- Guy C Brown
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom.
| | - Michael T Heneka
- Luxembourg Centre for Systems Biomedicine, University of Luxembourg, Belvaux, Luxembourg
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18
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Liu S, Butler CA, Ayton S, Reynolds EC, Dashper SG. Porphyromonas gingivalis and the pathogenesis of Alzheimer's disease. Crit Rev Microbiol 2024; 50:127-137. [PMID: 36597758 DOI: 10.1080/1040841x.2022.2163613] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 12/21/2022] [Accepted: 12/23/2022] [Indexed: 01/05/2023]
Abstract
The cause of Alzheimer's disease (AD), and the pathophysiological mechanisms involved, remain major unanswered questions in medical science. Oral bacteria, especially those species associated with chronic periodontitis and particularly Porphyromonas gingivalis, are being linked causally to AD pathophysiology in a subpopulation of susceptible individuals. P. gingivalis produces large amounts of proteolytic enzymes, haem and iron capture proteins, adhesins and internalins that are secreted and attached to the cell surface and concentrated onto outer membrane vesicles (OMVs). These enzymes and adhesive proteins have been shown to cause host tissue damage and stimulate inflammatory responses. The ecological and pathophysiological roles of P. gingivalis OMVs, their ability to disperse widely throughout the host and deliver functional proteins lead to the proposal that they may be the link between a P. gingivalis focal infection in the subgingivae during periodontitis and neurodegeneration in AD. P. gingivalis OMVs can cross the blood brain barrier and may accelerate AD-specific neuropathology by increasing neuroinflammation, plaque/tangle formation and dysregulation of iron homeostasis, thereby inducing ferroptosis leading to neuronal death and neurodegeneration.
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Affiliation(s)
- Sixin Liu
- School of Dentistry, University of Michigan, Ann Arbor, United States of America
| | - Catherine A Butler
- Centre for Oral Health Research, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Parkville, Australia
| | - Scott Ayton
- Melbourne Dementia Research Centre, Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Australia
| | - Eric C Reynolds
- Centre for Oral Health Research, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Parkville, Australia
| | - Stuart G Dashper
- Centre for Oral Health Research, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Parkville, Australia
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19
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Ko YK, Kim E, Lee EJ, Nam SJ, Kim Y, Kim S, Choi SY, Kim HY, Choi Y. Enrichment of infection-associated bacteria in the low biomass brain bacteriota of Alzheimer's disease patients. PLoS One 2024; 19:e0296307. [PMID: 38335187 PMCID: PMC10857729 DOI: 10.1371/journal.pone.0296307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 12/08/2023] [Indexed: 02/12/2024] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disease accompanied by neuroimmune inflammation in the frontal cortex and hippocampus. Recently, the presence of bacteria in AD-affected brains has been documented, prompting speculation about their potential role in AD-associated neuroinflammation. However, the characterization of bacteriota in human brains affected by AD remains inconclusive. This study aimed to investigate potential associations between specific bacteria and AD pathology by examining brain tissues from AD-associated neurodegenerative regions (frontal cortex and hippocampus) and the non-AD-associated hypothalamus. Employing 16S rRNA gene sequencing, 30 postmortem brain tissue samples from four individuals with normal brain histology (N) and four AD patients were analyzed, along with three blank controls. A remarkably low biomass characterized the brain bacteriota, with their overall structures delineated primarily by brain regions rather than the presence of AD. While most analyzed parameters exhibited no significant distinction in the brain bacteriota between the N and AD groups, the unique detection of Cloacibacterium normanense in the AD-associated neurodegenerative regions stood out. Additionally, infection-associated bacteria, as opposed to periodontal pathogens, were notably enriched in AD brains. This study's findings provide valuable insights into potential link between bacterial infection and neuroinflammation in AD.
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Affiliation(s)
- Yeon Kyeong Ko
- Department of Immunology and Molecular Microbiology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Republic of Korea
| | - Eunbi Kim
- Department of Immunology and Molecular Microbiology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Republic of Korea
| | - Eun-Jae Lee
- Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Soo Jeong Nam
- Department of Pathology, Asan Medical Center, Seoul, Republic of Korea
| | - Yeshin Kim
- Department of Neurology, Kangwon National University Hospital, Kangwon National University College of Medicine, Chuncheon, Republic of Korea
| | - Seongheon Kim
- Department of Neurology, Kangwon National University Hospital, Kangwon National University College of Medicine, Chuncheon, Republic of Korea
| | - Se-Young Choi
- Department of Physiology, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Republic of Korea
| | - Hyun Young Kim
- Department of Immunology and Molecular Microbiology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Republic of Korea
| | - Youngnim Choi
- Department of Immunology and Molecular Microbiology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Republic of Korea
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20
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Li R, Wang J, Xiong W, Luo Y, Feng H, Zhou H, Peng Y, He Y, Ye Q. The oral-brain axis: can periodontal pathogens trigger the onset and progression of Alzheimer's disease? Front Microbiol 2024; 15:1358179. [PMID: 38362505 PMCID: PMC10868393 DOI: 10.3389/fmicb.2024.1358179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 01/18/2024] [Indexed: 02/17/2024] Open
Abstract
Alzheimer's disease (AD) is the most prevalent form of dementia, characterized by a progressive cognitive decline. Sporadic AD, accounting for more than 95% of cases, may arise due to the influence of environmental factors. It was reported that periodontitis, a common oral ailment, shares several risk factors with AD, including advanced age, smoking, diabetes, and hypertension, among others. Periodontitis is an inflammatory disease triggered by dysbiosis of oral microorganisms, whereas Alzheimer's disease is characterized by neuroinflammation. Many studies have indicated that chronic inflammation can instigate brain AD-related pathologies, including amyloid-β plaques, Tau protein hyperphosphorylation, neuroinflammation, and neurodegeneration. The potential involvement of periodontal pathogens and/or their virulence factors in the onset and progression of AD by the oral-brain axis has garnered significant attention among researchers with ongoing investigations. This review has updated the periodontal pathogens potentially associated with AD, elucidating their impact on the central nervous system, immune response, and related pathological processes in the brain to provide valuable insights for future research on the oral-brain axis.
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Affiliation(s)
- Ruohan Li
- Center of Regenerative Medicine, Renmin Hospital of Wuhan University, Wuhan University, Wuhan, China
| | - Junnan Wang
- Center of Regenerative Medicine, Renmin Hospital of Wuhan University, Wuhan University, Wuhan, China
| | - Wei Xiong
- Center of Regenerative Medicine, Renmin Hospital of Wuhan University, Wuhan University, Wuhan, China
| | - Yu Luo
- Center of Regenerative Medicine, Renmin Hospital of Wuhan University, Wuhan University, Wuhan, China
- Department of Stomatology, Renmin Hospital of Wuhan University, Wuhan University, Wuhan, China
| | - Huixian Feng
- Department of Stomatology, Renmin Hospital of Wuhan University, Wuhan University, Wuhan, China
| | - Heng Zhou
- Center of Regenerative Medicine, Renmin Hospital of Wuhan University, Wuhan University, Wuhan, China
| | - Youjian Peng
- Department of Stomatology, Renmin Hospital of Wuhan University, Wuhan University, Wuhan, China
| | - Yan He
- Institute of Regenerative and Translational Medicine, Tianyou Hospital, Wuhan University of Science and Technology, Wuhan, China
| | - Qingsong Ye
- Center of Regenerative Medicine, Renmin Hospital of Wuhan University, Wuhan University, Wuhan, China
- Department of Stomatology, Renmin Hospital of Wuhan University, Wuhan University, Wuhan, China
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21
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Li Z, Wang H, Yin Y. Peripheral inflammation is a potential etiological factor in Alzheimer's disease. Rev Neurosci 2024; 35:99-120. [PMID: 37602685 DOI: 10.1515/revneuro-2023-0049] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 07/27/2023] [Indexed: 08/22/2023]
Abstract
Peripheral inflammation could constitute a risk factor for AD. This review summarizes the research related to peripheral inflammation that appears to have a relationship with Alzheimer's disease. We find there are significant associations between AD and peripheral infection induced by various pathogens, including herpes simplex virus type 1, cytomegalovirus, Epstein-Barr virus, human immunodeficiency virus, severe acute respiratory syndrome coronavirus 2, Porphyromonas gingivalis, Helicobacter pylori, and Toxoplasma gondii. Chronic inflammatory diseases are also reported to contribute to the pathophysiology of AD. The mechanisms by which peripheral inflammation affects the pathophysiology of AD are complex. Pathogen-derived neurotoxic molecule composition, disrupted BBB, and dysfunctional neurogenesis may all play a role in peripheral inflammation, promoting the development of AD. Anti-pathogenic medications and anti-inflammatory treatments are reported to decrease the risk of AD. Studies that could improve understanding the associations between AD and peripheral inflammation are needed. If our assumption is correct, early intervention against inflammation may be a potential method of preventing and treating AD.
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Affiliation(s)
- Ziyuan Li
- Department of Nuclear Medicine, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Kongjiang Road 1665, Yangpu District, Shanghai 200092, China
| | - Hui Wang
- Department of Nuclear Medicine, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Kongjiang Road 1665, Yangpu District, Shanghai 200092, China
| | - Yafu Yin
- Department of Nuclear Medicine, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Kongjiang Road 1665, Yangpu District, Shanghai 200092, China
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22
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Villar A, Paladini S, Cossatis J. Periodontal Disease and Alzheimer's: Insights from a Systematic Literature Network Analysis. J Prev Alzheimers Dis 2024; 11:1148-1165. [PMID: 39044527 PMCID: PMC11266257 DOI: 10.14283/jpad.2024.79] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 03/03/2024] [Indexed: 07/25/2024]
Abstract
This study investigated the relationship between periodontal disease (PD) and Alzheimer's Disease (AD) through a Systematic Literature Network Analysis (SLNA), combining bibliometric analysis with a Systematic Literature Review (SLR). Analyzing 328 documents from 2000 to 2023, we utilized the Bibliometrix R-package for multiple bibliometric analysis. The SLR primarily centered on the 47 most globally cited papers, highlighting influential research. Our study reveals a positive correlation between Periodontal Disease (PD) and Alzheimer's Disease (AD), grounded in both biological plausibility and a comprehensive review of the literature, yet the exact causal relationship remains a subject of ongoing scientific investigation. We conducted a detailed analysis of the two main pathways by which PD could contribute to brain inflammation: (a) the Inflammatory Cascade, and (b) Microbial Involvement. The results of our SLNA emphasize the importance of oral health in reducing Alzheimer's risk, suggesting that managing periodontal health could be an integral part of Alzheimer's prevention and treatment strategies. The insights from this SLNA pave the way for future research and clinical practices, underscoring the necessity of interdisciplinary methods in both the investigation and treatment of neurodegenerative diseases like Alzheimer's. Furthermore, our study presents a prospective research roadmap to support ongoing advancement in this field.
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Affiliation(s)
- A Villar
- Alice Villar, Faculty of Medicine, University Castelo Branco (UCB), Brazil,
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23
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Zhang M, Mi N, Ying Z, Lin X, Jin Y. Advances in the prevention and treatment of Alzheimer's disease based on oral bacteria. Front Psychiatry 2023; 14:1291455. [PMID: 38156323 PMCID: PMC10754487 DOI: 10.3389/fpsyt.2023.1291455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2023] [Accepted: 11/22/2023] [Indexed: 12/30/2023] Open
Abstract
With the global population undergoing demographic shift towards aging, the prevalence of Alzheimer's disease (AD), a prominent neurodegenerative disorder that primarily afflicts individuals aged 65 and above, has increased across various geographical regions. This phenomenon is accompanied by a concomitant decline in immune functionality and oral hygiene capacity among the elderly, precipitating compromised oral functionality and an augmented burden of dental plaque. Accordingly, oral afflictions, including dental caries and periodontal disease, manifest with frequency among the geriatric population worldwide. Recent scientific investigations have unveiled the potential role of oral bacteria in instigating both local and systemic chronic inflammation, thereby delineating a putative nexus between oral health and the genesis and progression of AD. They further proposed the oral microbiome as a potentially modifiable risk factor in AD development, although the precise pathological mechanisms and degree of association have yet to be fully elucidated. This review summarizes current research on the relationship between oral bacteria and AD, describing the epidemiological and pathological mechanisms that may potentially link them. The purpose is to enrich early diagnostic approaches by incorporating emerging biomarkers, offering novel insights for clinicians in the early detection of AD. Additionally, it explores the potential of vaccination strategies and guidance for clinical pharmacotherapy. It proposes the development of maintenance measures specifically targeting oral health in older adults and advocates for guiding elderly patients in adopting healthy lifestyle habits, ultimately aiming to indirectly mitigate the progression of AD while promoting oral health in the elderly.
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Affiliation(s)
| | | | | | | | - Ying Jin
- Department of Stomatology, Shengjing Hospital of China Medical University, Shenyang, China
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24
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Qian J, Lu J, Cheng S, Zou X, Tao Q, Wang M, Wang N, Zheng L, Liao W, Li Y, Yan F. Periodontitis salivary microbiota exacerbates colitis-induced anxiety-like behavior via gut microbiota. NPJ Biofilms Microbiomes 2023; 9:93. [PMID: 38062089 PMCID: PMC10703887 DOI: 10.1038/s41522-023-00462-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 11/20/2023] [Indexed: 12/18/2023] Open
Abstract
The gut-brain axis is a bidirectional communication system between the gut and central nervous system. Many host-related factors can affect gut microbiota, including oral bacteria, making the brain a vulnerable target via the gut-brain axis. Saliva contains a large number of oral bacteria, and periodontitis, a common oral disease, can change the composition of salivary microbiota. However, the role and mechanism of periodontitis salivary microbiota (PSM) on the gut-brain axis remain unclear. Herein, we investigated the nature and mechanisms of this relationship using the mice with dextran sulfate sodium salt (DSS)-induced anxiety-like behavior. Compared with healthy salivary microbiota, PSM worsened anxiety-like behavior; it significantly reduced the number of normal neurons and activated microglia in DSS mice. Antibiotic treatment eliminated the effect of PSM on anxiety-like behavior, and transplantation of fecal microbiota from PSM-gavaged mice exacerbated anxiety-like behavior. These observations indicated that the anxiety-exacerbating effect of PSM was dependent on the gut microbiota. Moreover, the PSM effect on anxiety-like behavior was not present in non-DSS mice, indicating that DSS treatment was a prerequisite for PSM to exacerbate anxiety. Mechanistically, PSM altered the histidine metabolism in both gut and brain metabolomics. Supplementation of histidine-related metabolites had a similar anxiety-exacerbating effect as that of PSM, suggesting that histidine metabolism may be a critical pathway in this process. Our results demonstrate that PSM can exacerbate colitis-induced anxiety-like behavior by directly affecting the host gut microbiota, emphasizing the importance of oral diseases in the gut-brain axis.
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Affiliation(s)
- Jun Qian
- Nanjing Stomatological Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Jiangyue Lu
- Nanjing Stomatological Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Shuyu Cheng
- Nanjing Stomatological Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Xihong Zou
- Nanjing Stomatological Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Qing Tao
- Center for Translational Medicine and Jiangsu Key Laboratory of Molecular Medicine, Medical School, Nanjing University, Nanjing, China
| | - Min Wang
- Nanjing Stomatological Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Nannan Wang
- Nanjing Stomatological Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Lichun Zheng
- Nanjing Stomatological Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Wenzheng Liao
- Nanjing Stomatological Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Yanfen Li
- Nanjing Stomatological Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China.
| | - Fuhua Yan
- Nanjing Stomatological Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China.
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25
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Hernández Martínez CDJ, Felix Silva P, Salvador SL, Messora M, Palioto DB. Chronological analysis of periodontal bone loss in experimental periodontitis in mice. Clin Exp Dent Res 2023; 9:1009-1020. [PMID: 37997536 PMCID: PMC10728515 DOI: 10.1002/cre2.806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Revised: 10/04/2023] [Accepted: 10/12/2023] [Indexed: 11/25/2023] Open
Abstract
OBJECTIVES Periodontal disease is understood to be a result of dysbiotic interactions between the host and the biofilm, causing a unique reaction for each individual, which in turn characterizes their susceptibility. The objective of this study was to chronologically evaluate periodontal tissue destruction induced by systemic bacterial challenge in known susceptible (BALB/c) and resistant (C57BL/6) mouse lineages. MATERIAL AND METHODS Animals, 6-8 weeks old, were allocated into three experimental groups: Negative control (C), Gavage with sterile carboxymethyl cellulose 2%-without bacteria (Sham), and Gavage with carboxymethyl cellulose 2% + Porphyromonas gingivalis (Pg-W83). Before infection, all animals received antibiotic treatment (sulfamethoxazole/trimethoprim, 400/80 mg/5 mL) for 7 days, followed by 3 days of rest. Microbial challenge was performed 3 times per week for 1, 2, or 3 weeks. After that, the animals were kept until the completion of 42 days of experiments, when they were euthanized. The alveolar bone microarchitecture was assessed by computed microtomography. RESULTS Both C57BL/6 and BALB/c mice exhibited significant bone volume loss and lower trabecular thickness as well as greater bone porosity compared to the (C) and (Sham) groups after 1 week of microbial challenge (p < .001). When comparing only the gavage groups regarding disease implantation, time and lineage, it was possible to observe that within 1 week of induction the disease was more established in BALB/c than in C57BL/6 (p < .05). CONCLUSIONS Our results reflected that after 1 week of microbial challenge, there was evidence of alveolar bone loss for both lineages, with the loss observed in BALB/c mice being more pronounced.
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Affiliation(s)
- Cristhiam de J. Hernández Martínez
- Department of Oral & Maxillofacial Surgery and Periodontology, Ribeirão Preto Dental SchoolUniversity of Sao Paulo—USPRibeirão Preto SPBrazil
| | - Pedro Felix Silva
- Department of Oral & Maxillofacial Surgery and Periodontology, Ribeirão Preto Dental SchoolUniversity of Sao Paulo—USPRibeirão Preto SPBrazil
| | - Sergio L. Salvador
- Department of Clinical Analyses, School of Pharmaceutical Sciences of Ribeirao PretoUniversity of Sao Paulo—USPRibeirão Preto SPBrazil
| | - Michel Messora
- Department of Oral & Maxillofacial Surgery and Periodontology, Ribeirão Preto Dental SchoolUniversity of Sao Paulo—USPRibeirão Preto SPBrazil
| | - Daniela B. Palioto
- Department of Oral & Maxillofacial Surgery and Periodontology, Ribeirão Preto Dental SchoolUniversity of Sao Paulo—USPRibeirão Preto SPBrazil
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26
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Ma X, Shin YJ, Yoo JW, Park HS, Kim DH. Extracellular vesicles derived from Porphyromonas gingivalis induce trigeminal nerve-mediated cognitive impairment. J Adv Res 2023; 54:293-303. [PMID: 36796586 DOI: 10.1016/j.jare.2023.02.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 02/09/2023] [Accepted: 02/10/2023] [Indexed: 02/17/2023] Open
Abstract
INTRODUCTION Porphyromonas gingivalis (PG)-infected periodontitis is in close connection with the development of Alzheimer's disease (AD). PG-derived extracellular vesicles (pEVs) contain inflammation-inducing virulence factors, including gingipains (GPs) and lipopolysaccharide (LPS). OBJECTIVES To understand how PG could cause cognitive decline, we investigated the effects of PG and pEVs on the etiology of periodontitis and cognitive impairment in mice. METHODS Cognitive behaviors were measured in the Y-maze and novel object recognition tasks. Biomarkers were measured using ELISA, qPCR, immunofluorescence assay, and pyrosequencing. RESULTS pEVs contained neurotoxic GPs and inflammation-inducible fimbria protein and LPS. Gingivally exposed, but not orally gavaged, PG or pEVs caused periodontitis and induced memory impairment-like behaviors. Gingival exposure to PG or pEVs increased TNF-α expression in the periodontal and hippocampus tissues. They also increased hippocampal GP+Iba1+, LPS+Iba1+, and NF-κB+Iba1+ cell numbers. Gingivally exposed PG or pEVs decreased BDNF, claudin-5, and N-methyl-D-aspartate receptor expression and BDNF+NeuN+ cell number. Gingivally exposed fluorescein-5-isothiocyanate-labeled pEVs (F-pEVs) were detected in the trigeminal ganglia and hippocampus. However, right trigeminal neurectomy inhibited the translocation of gingivally injected F-EVs into the right trigeminal ganglia. Gingivally exposed PG or pEVs increased blood LPS and TNF-α levels. Furthermore, they caused colitis and gut dysbiosis. CONCLUSION Gingivally infected PG, particularly pEVs, may cause cognitive decline with periodontitis. PG products pEVs and LPS may be translocated into the brain through the trigeminal nerve and periodontal blood pathways, respectively, resulting in the cognitive decline, which may cause colitis and gut dysbiosis. Therefore, pEVs may be a remarkable risk factor for dementia.
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Affiliation(s)
- Xiaoyang Ma
- Neurobiota Research Center, College of Pharmacy, Kyung Hee University, 26, Kyungheedae-ro, Dong-daemun-gu, Seoul 02447, Korea.
| | - Yoon-Jung Shin
- Neurobiota Research Center, College of Pharmacy, Kyung Hee University, 26, Kyungheedae-ro, Dong-daemun-gu, Seoul 02447, Korea.
| | - Jong-Wook Yoo
- Neurobiota Research Center, College of Pharmacy, Kyung Hee University, 26, Kyungheedae-ro, Dong-daemun-gu, Seoul 02447, Korea.
| | - Hee-Seo Park
- Neurobiota Research Center, College of Pharmacy, Kyung Hee University, 26, Kyungheedae-ro, Dong-daemun-gu, Seoul 02447, Korea.
| | - Dong-Hyun Kim
- Neurobiota Research Center, College of Pharmacy, Kyung Hee University, 26, Kyungheedae-ro, Dong-daemun-gu, Seoul 02447, Korea.
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27
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Kumari S, Dhapola R, Sharma P, Singh SK, Reddy DH. Implicative role of Cytokines in Neuroinflammation mediated AD and associated signaling pathways: Current Progress in molecular signaling and therapeutics. Ageing Res Rev 2023; 92:102098. [PMID: 39492425 DOI: 10.1016/j.arr.2023.102098] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 09/30/2023] [Accepted: 10/23/2023] [Indexed: 11/05/2024]
Abstract
Alzheimer's Disease (AD) is one of the most devastating age-related disorder causing significant social and economic burden worldwide. It affects the cognitive and social behavior of individuals and characterized by accumulation of Aβ, phosphorylated tau and cytokines formation. The synthesis and release of cytokines are regulated by specific groups of immune and non-immune cells in response to microglia or astrocyte activation through multiple pathways. Physiologically, microglia assert an anti-inflammatory, quiescent state with minimal cytokine expression and little phagocytic activity in motion to carry out their housekeeping role to eliminate pathogens, aggregated Aβ and tau protein. However, they develop a phagocytic nature and overexpress cytokine gene modules in response to certain stimuli in AD. Microglia and astrocytes upon chronic activation release an enormous amount of inflammatory cytokines due to interaction with formed Aβ and neurofibrillary tangle. Gut microbiota dysbiosis also stimulates the release of inflammatory cytokines contributing to AD pathogenesis. In addition, the dysregulation of few signaling pathways significantly influences the development of disease, and the pace of advancement also rises with age. This review sheds light on multiple pathways results into neuroinflammation triggered by activated cytokines worsening AD pathology and making it an appropriate target for AD treatment. This review also included drugs targeting different neuroinflammation pathways under clinical and preclinical studies that are found to be effective in attenuating the disease pathology.
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Affiliation(s)
- Sneha Kumari
- Department of Pharmacology, School of Health Sciences, Central University of Punjab, Ghudda, Bathinda-151401, Punjab, India
| | - Rishika Dhapola
- Department of Pharmacology, School of Health Sciences, Central University of Punjab, Ghudda, Bathinda-151401, Punjab, India
| | - Prajjwal Sharma
- Department of Pharmacology, School of Health Sciences, Central University of Punjab, Ghudda, Bathinda-151401, Punjab, India
| | - Sunil K Singh
- Department of Zoology, School of Biological Sciences, Central University of Punjab, Ghudda, Bathinda, Punjab, India.
| | - Dibbanti HariKrishna Reddy
- Department of Pharmacology, School of Health Sciences, Central University of Punjab, Ghudda, Bathinda-151401, Punjab, India.
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28
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Zhao C, Kuraji R, Ye C, Gao L, Radaic A, Kamarajan P, Taketani Y, Kapila YL. Nisin a probiotic bacteriocin mitigates brain microbiome dysbiosis and Alzheimer's disease-like neuroinflammation triggered by periodontal disease. J Neuroinflammation 2023; 20:228. [PMID: 37803465 PMCID: PMC10557354 DOI: 10.1186/s12974-023-02915-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Accepted: 09/28/2023] [Indexed: 10/08/2023] Open
Abstract
INTRODUCTION Periodontitis-related oral microbial dysbiosis is thought to contribute to Alzheimer's disease (AD) neuroinflammation and brain amyloid production. Since probiotics can modulate periodontitis/oral dysbiosis, this study examined the effects of a probiotic/lantibiotic, nisin, in modulating brain pathology triggered by periodontitis. METHODS A polymicrobial mouse model of periodontal disease was used to evaluate the effects of this disease on brain microbiome dysbiosis, neuroinflammation, Alzheimer's-related changes, and nisin's therapeutic potential in this context. RESULTS 16S sequencing and real-time PCR data revealed that Nisin treatment mitigated the changes in the brain microbiome composition, diversity, and community structure, and reduced the levels of periodontal pathogen DNA in the brain induced by periodontal disease. Nisin treatment significantly decreased the mRNA expression of pro-inflammatory cytokines (Interleukin-1β/IL-1 β, Interleukin 6/IL-6, and Tumor Necrosis Factor α/TNF-α) in the brain that were elevated by periodontal infection. In addition, the concentrations of amyloid-β 42 (Aβ42), total Tau, and Tau (pS199) (445.69 ± 120.03, 1420.85 ± 331.40, 137.20 ± 36.01) were significantly higher in the infection group compared to the control group (193.01 ± 31.82, 384.27 ± 363.93, 6.09 ± 10.85), respectively. Nisin treatment markedly reduced the Aβ42 (261.80 ± 52.50), total Tau (865.37 ± 304.93), and phosphorylated Tau (82.53 ± 15.77) deposition in the brain of the infection group. DISCUSSION Nisin abrogation of brain microbiome dysbiosis induces beneficial effects on AD-like pathogenic changes and neuroinflammation, and thereby may serve as a potential therapeutic for periodontal-dysbiosis-related AD.
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Affiliation(s)
- Chuanjiang Zhao
- Department of Orofacial Sciences, School of Dentistry, University of California San Francisco, San Francisco, CA, 94143, USA
- Department of Periodontology, Hospital of Stomatology, Sun Yat-Sen University, Guangzhou, 510050, China
- Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Sun Yat-Sen University, Guangzhou, 510050, China
| | - Ryutaro Kuraji
- Department of Orofacial Sciences, School of Dentistry, University of California San Francisco, San Francisco, CA, 94143, USA
- Department of Periodontology, The Nippon Dental University School of Life Dentistry at Tokyo, Tokyo, 102-8159, Japan
| | - Changchang Ye
- Department of Orofacial Sciences, School of Dentistry, University of California San Francisco, San Francisco, CA, 94143, USA
- Department of Periodontology, West China School of Stomatology, National Clinical Research Center for Oral Diseases, State Key Laboratory of Oral Diseases, Sichuan University, Chengdu, 610093, China
| | - Li Gao
- Department of Orofacial Sciences, School of Dentistry, University of California San Francisco, San Francisco, CA, 94143, USA
- Department of Periodontology, Hospital of Stomatology, Sun Yat-Sen University, Guangzhou, 510050, China
- Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Sun Yat-Sen University, Guangzhou, 510050, China
| | - Allan Radaic
- Department of Orofacial Sciences, School of Dentistry, University of California San Francisco, San Francisco, CA, 94143, USA
- Department of Biosystems and Function and Periodontics, School of Dentistry, University of California Los Angeles, Los Angeles, CA, 90024, USA
| | - Pachiyappan Kamarajan
- Department of Orofacial Sciences, School of Dentistry, University of California San Francisco, San Francisco, CA, 94143, USA
- Department of Biosystems and Function and Periodontics, School of Dentistry, University of California Los Angeles, Los Angeles, CA, 90024, USA
| | - Yoshimasa Taketani
- Department of Biosystems and Function and Periodontics, School of Dentistry, University of California Los Angeles, Los Angeles, CA, 90024, USA
- Division of Periodontology, Department of Oral Biology and Tissue Engineering, Meikai University School of Dentistry, Sakado, 350-0283, Japan
| | - Yvonne L Kapila
- Department of Orofacial Sciences, School of Dentistry, University of California San Francisco, San Francisco, CA, 94143, USA.
- Department of Biosystems and Function and Periodontics, School of Dentistry, University of California Los Angeles, Los Angeles, CA, 90024, USA.
- Section of Biosystems and Function, Section of Periodontology, UCLA School of Dentistry, 10833 Le Conte Ave, Box 951668, Los Angeles, CA, 90095-1668, USA.
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Skallevold HE, Rokaya N, Wongsirichat N, Rokaya D. Importance of oral health in mental health disorders: An updated review. J Oral Biol Craniofac Res 2023; 13:544-552. [PMID: 37396968 PMCID: PMC10314291 DOI: 10.1016/j.jobcr.2023.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 06/05/2023] [Accepted: 06/14/2023] [Indexed: 07/04/2023] Open
Abstract
Background Mental disorders are indeed an expanding threat, which requires raised awareness, education, prevention, and treatment initiatives nationally and globally. This review presents an updated review on the relationships between oral health and mental health disorders and the importance of oral health in mental health disorders. Method A literature search was done regarding mental disorders and oral health approaches in Google Scholar and PubMed from the year 1995 until 2023. All the English-language papers were evaluated based on the inclusion criteria. Publications included original research papers, review articles and book chapters. Results Common mental disorders include depression, anxiety, bipolar disorder, Schizophrenia, dementia, and alcohol and drug use disorders. The interplay of oral health and mental disorders involves dysregulated microbiome, translocated bacteria, and systemic inflammation, among others. Conclusion There is a complex relationship between mental disorders and oral diseases. Various oral health problems are associated with mental health problems. The interplay of oral health and mental disorders involves dysregulated microbiome, translocated bacteria, and systemic inflammation, among others. Mental health nurses including physicians and dental professionals should be involved in the oral health care of mental health disorder patients. Therefore, multidisciplinary should be involved in the care of mental health disorders, and they should consider oral health care as an essential part of their care for patients with mental health disorders. Future investigations should strive to elucidate the exact biological relationships, to develop new directions for treatment.
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Affiliation(s)
- Hans Erling Skallevold
- Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand
| | | | - Natthamet Wongsirichat
- Faculty of Dentistry, Bangkok Thonburi University, 16/10 Taweewatana, Bangkok, 10170, Thailand
| | - Dinesh Rokaya
- Department of Clinical Dentistry, Walailak University International College of Dentistry, Bangkok, 10400, Thailand
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Alleviation of Porphyromonas gingivalis or Its Extracellular Vesicles Provoked Periodontitis and Cognitive Impairment by Lactobacillus pentosus NK357 and Bifidobacterium bifidum NK391. Nutrients 2023; 15:nu15051068. [PMID: 36904068 PMCID: PMC10005711 DOI: 10.3390/nu15051068] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 02/16/2023] [Accepted: 02/19/2023] [Indexed: 02/25/2023] Open
Abstract
Porphyromonas gingivalis (PG) is closely involved in the outbreak of periodontitis and cognitive impairment (CI). Herein, we examined the effects of anti-inflammatory Lactobacillus pentosus NK357 and Bifidobacterium bifidum NK391 on PG- or its extracellular vesicles (pEVs)-induced periodontitis and CI in mice. Oral administration of NK357 or NK391 significantly decreased PG-induced tumor necrosis factor (TNF)-α, receptor activator of nuclear factors κB (RANK), and RANK ligand (RANKL) expression, gingipain (GP)+lipopolysaccharide (LPS)+ and NF-κB+CD11c+ populations, and PG 16S rDNA level in the periodontal tissue. Their treatments also suppressed PG-induced CI -like behaviors, TNF-α expression and NF-κB-positive immune cells in the hippocampus and colon, while PG-suppressed hippocampal BDNF and N-methyl-D-aspartate receptor (NMDAR) expression increased. The combination of NK357 and NK391 additively alleviated PG- or pEVs-induced periodontitis, neuroinflammation, CI-like behaviors, colitis, and gut microbiota dysbiosis and increased PG- or pEVs-suppressed BDNF and NMDAR expression in the hippocampus. In conclusion, NK357 and NK391 may alleviate periodontitis and dementia by regulating NF-κB, RANKL/RANK, and BDNF-NMDAR signaling and gut microbiota.
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Lamphere AK, Nieto VK, Kiser JR, Haddlesey CB. Potential mechanisms between periodontitis and Alzheimer's disease: a scoping review. CANADIAN JOURNAL OF DENTAL HYGIENE : CJDH = JOURNAL CANADIEN DE L'HYGIENE DENTAIRE : JCHD 2023; 57:52-60. [PMID: 36968797 PMCID: PMC10032644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 08/03/2022] [Accepted: 10/25/2022] [Indexed: 03/29/2023]
Abstract
Background Research has suggested 2 potential mechanisms by which the periodontal inflammatory response may communicate to distant organs: 1) direct translocation of periodontal bacteria from the oral cavity to another organ system; and 2) inflammation as a result of metastatic periodontal inflammation. The purpose of this scoping review is to explore these mechanisms as potential mediators between periodontitis and Alzheimer's disease. Methods A reiterative literature search of peer-reviewed articles was performed in the PubMed and Scopus databases using keywords or combinations such as Alzheimer's disease AND periodontitis OR periodontal disease AND inflammation. Results A total of 777 articles were identified. After eliminating duplicates and reviewing titles and abstracts, 84 articles were selected for full-text review. Following full-text review, 19 articles met the eligibility criteria for the study. Discussion The review of the literature highlights how periodontitis may contribute to neuroinflammation by the introduction of periodontal bacteria and/or proinflammatory cytokines locally produced at the periodontium. Conclusion Inflammation is an important mechanism in the onset and progression of both periodontitis and Alzheimer's disease. Nevertheless, further studies are necessary to better understand the multifactorial pathogenesis of Alzheimer's disease.
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Affiliation(s)
- Abrielle K Lamphere
- Assistant clinical professor in dentistry, University of Indiana School of Dentistry, Indianapolis, IN, USA
| | - Valerie K Nieto
- Clinical lecturer in dentistry, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - Jessica R Kiser
- Adjunct clinical lecturer in dentistry, University of Michigan School of Dentistry, Ann Arbor, MI, USA
| | - Chris B Haddlesey
- Adjunct clinical lecturer in dentistry, University of Michigan School of Dentistry, Ann Arbor, MI, USA
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Fu Y, Xu X, Zhang Y, Yue P, Fan Y, Liu M, Chen J, Liu A, Zhang X, Bao F. Oral Porphyromonas gingivalis Infections Increase the Risk of Alzheimer's Disease: A Review. ORAL HEALTH & PREVENTIVE DENTISTRY 2023; 21:7-16. [PMID: 36651311 PMCID: PMC11619833 DOI: 10.3290/j.ohpd.b3818045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 11/10/2022] [Indexed: 01/19/2023]
Abstract
Periodontal disease (PD) and Alzheimer's disease (AD) are inflammatory diseases affecting the adult population of the world. PD is mainly caused by infection with Porphyromonas gingivalis (P. gingivalis) and by the synergistic action of various microorganisms. These microorganisms penetrate into the subgingival tissue and cause bacteremia, leading to disruption of the homeostasis of the internal environment of the body. Virulence factors known as gingipains, which are cysteine proteases and other toxins, including fimbria and lipopolysaccharides (LPS), are strongly associated with periodontitis and other systemic inflammation. PD has a known polymicrobial aetiology, and patients who eventually develop sporadic AD tend to have recurrent infections before a clinical diagnosis of dementia. AD, the most common neurodegenerative disease, is characterised by poor memory and specific hallmark proteins. An increasing number of studies have shown that periodontal pathogens are increasingly associated with this form of dementia. Many articles have shown that P. gingivalis infections directly increase the risk of PD and may indirectly lead to the development of AD. However, these links and probable pathogenesis remain to be explored. The aim of this review was to explore whether P. gingivalis periodontal infection is associated with AD and to provide possible mechanisms of association.
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Affiliation(s)
- Yuwen Fu
- Bachelor’s Student, Yunnan Province Key Laboratory for Tropical Infectious Diseases in Universities, Kunming Medical University, Kunming, Yunnan, China; College of Stomatology – Kunming Medical University, Kunming, Yunnan, China. Conducted the database search and screening drafted the manuscript
| | - Xin Xu
- Master’s Student, Yunnan Province Key Laboratory for Tropical Infectious Diseases in Universities, Kunming Medical University, Kunming, Yunnan, China. Conducted the database search and screening
| | - Yu Zhang
- Master’s Student, Yunnan Province Key Laboratory for Tropical Infectious Diseases in Universities, Kunming Medical University, Kunming, Yunnan, China. Conducted the database search and screening
| | - Peng Yue
- Master’s Student, Yunnan Province Key Laboratory for Tropical Infectious Diseases in Universities, Kunming Medical University, Kunming, Yunnan, China. Conducted the database search and screening
| | - Yuxin Fan
- Master’s Student, Yunnan Province Key Laboratory for Tropical Infectious Diseases in Universities, Kunming Medical University, Kunming, Yunnan, China. Conducted the database search and screening
| | - Meixiao Liu
- Master’s Student, Yunnan Province Key Laboratory for Tropical Infectious Diseases in Universities, Kunming Medical University, Kunming, Yunnan, China. Conducted the database search and screening
| | - Jingjing Chen
- Master’s Student, Yunnan Province Key Laboratory for Tropical Infectious Diseases in Universities, Kunming Medical University, Kunming, Yunnan, China. Conducted the database search and screening
| | - Aihua Liu
- Professor, Yunnan Province Key Laboratory for Tropical Infectious Diseases in Universities, Kunming Medical University, Kunming, Yunnan, China. Conceived and designed the study, revised and approved the manuscript
| | - Xiufeng Zhang
- Associate Professor, College of Forensic Medicine – Kunming Medical University, Kunming, Yunnan, China. Conceived and designed the study
| | - Fukai Bao
- Professor, Yunnan Province Key Laboratory for Tropical Infectious Diseases in Universities, Kunming Medical University, Kunming, Yunnan, China. Conceived and designed the study, revised and approved the manuscript
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Liu S, Dashper SG, Zhao R. Association Between Oral Bacteria and Alzheimer's Disease: A Systematic Review and Meta-Analysis. J Alzheimers Dis 2023; 91:129-150. [PMID: 36404545 DOI: 10.3233/jad-220627] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Pre-clinical evidence implicates oral bacteria in the pathogenesis of Alzheimer's disease (AD), while clinical studies show diverse results. OBJECTIVE To comprehensively assess the association between oral bacteria and AD with clinical evidence. METHODS Studies investigating the association between oral bacteria and AD were identified through a systematic search of six databases PubMed, Embase, Cochrane Central Library, Scopus, ScienceDirect, and Web of Science. Methodological quality ratings of the included studies were performed. A best evidence synthesis was employed to integrate the results. When applicable, a meta-analysis was conducted using a random-effect model. RESULTS Of the 16 studies included, ten investigated periodontal pathobionts and six were microbiome-wide association studies. Samples from the brain, serum, and oral cavity were tested. We found over a ten-fold and six-fold increased risk of AD when there were oral bacteria (OR = 10.68 95% CI: 4.48-25.43; p < 0.00001, I2 = 0%) and Porphyromonas gingivalis (OR = 6.84 95% CI: 2.70-17.31; p < 0.0001, I2 = 0%) respectively in the brain. While AD patients exhibited lower alpha diversity of oral microbiota than healthy controls, the findings of bacterial communities were inconsistent among studies. The best evidence synthesis suggested a moderate level of evidence for an overall association between oral bacteria and AD and for oral bacteria being a risk factor for AD. CONCLUSION Current evidence moderately supports the association between oral bacteria and AD, while the association was strong when oral bacteria were detectable in the brain. Further evidence is needed to clarify the interrelationship between both individual species and bacterial communities and the development of AD.
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Affiliation(s)
- Sixin Liu
- School of Dentistry, University of Michigan, Ann Arbor, MI, USA
| | - Stuart G Dashper
- Centre for Oral Health Research, Melbourne Dental School, Bio21 Institute, The University of Melbourne, Parkville, Australia
| | - Rui Zhao
- Department of Stomatology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, China
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MORIKAWA TETSURO, UEHARA OSAMU, PAUDEL DURGA, YOSHIDA KOKI, HARADA FUMIYA, HIRAKI DAICHI, SATO JUN, MATSUOKA HIROFUMI, KURAMITSU YASUHIRO, MICHIKAWA MAKOTO, ABIKO YOSHIHIRO. Systemic Administration of Lipopolysaccharide from Porphyromonas gingivalis Decreases Neprilysin Expression in the Mouse Hippocampus. In Vivo 2023; 37:163-172. [PMID: 36593043 PMCID: PMC9843806 DOI: 10.21873/invivo.13065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 11/29/2022] [Accepted: 11/30/2022] [Indexed: 01/03/2023]
Abstract
BACKGROUND/AIM Alzheimer's disease is the most common type of neurodegenerative disorder in elderly individuals worldwide. Increasing evidence suggests that periodontal diseases are involved in the pathogenesis of Alzheimer's disease, and an association between periodontitis and amyloid-β deposition in elderly individuals has been demonstrated. The aim of the present study was to examine the effects of systemic administration of Porphyromonas gingivalis-derived lipopolysaccharide (PG-LPS) on neprilysin expression in the hippocampus of adult and senescence-accelerated mice. MATERIALS AND METHODS PG-LPS diluted in saline was intraperitoneally administered to male C57BL/6J and senescence-accelerated mouse prone 8 (SAMP8) mice at a dose of 5 mg/kg every 3 days for 3 months. Both C57BL/6J and SAMP8 mice administered saline without PG-LPS comprised the control group. The mRNA expression levels of neprilysin and interleukin (IL)-10 were evaluated using the quantitative reverse transcriptase-polymerase chain reaction. The protein levels of neprilysin were assessed using western blotting. Sections of the brain tissues were immunohistochemically stained. RESULTS The serum IL-10 concentration significantly increased in both mouse strains after stimulation with PG-LPS. Neprilysin expression at both mRNA and protein levels was significantly lower in the SAMP8 PG-LPS group than those in the SAMP8 control group; however, they did not differ in PG-LPS-treated or non-treated C57BL/6J mice. Additionally, the immunofluorescence intensity of neprilysin in the CA3 region of the hippocampus in PG-LPS-treated SAMP8 mice was significantly lower than that in control SAMP8 mice. CONCLUSION Porphyromonas gingivalis may reduce the expression of neprilysin in elderly individuals and thus increase amyloid-β deposition.
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Affiliation(s)
- TETSURO MORIKAWA
- Division of Oral Medicine and Pathology, Department of Human Biology and Pathophysiology, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Japan
| | - OSAMU UEHARA
- Division of Disease Control and Molecular Epidemiology, Department of Oral Growth and Development, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Japan
| | - DURGA PAUDEL
- Advanced Research Promotion Center, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Japan
| | - KOKI YOSHIDA
- Division of Oral Medicine and Pathology, Department of Human Biology and Pathophysiology, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Japan
| | - FUMIYA HARADA
- Division of Oral and Maxillofacial Surgery, Department of Human Biology and Pathophysiology, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Japan
| | - DAICHI HIRAKI
- Division of Reconstructive Surgery for Oral and Maxillofacial Region, Department of Human Biology and Pathophysiology, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Japan
| | - JUN SATO
- Division of Oral Medicine and Pathology, Department of Human Biology and Pathophysiology, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Japan
| | - HIROFUMI MATSUOKA
- Division of Disease Control and Molecular Epidemiology, Department of Oral Growth and Development, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Japan
| | - YASUHIRO KURAMITSU
- Advanced Research Promotion Center, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Japan
| | - MAKOTO MICHIKAWA
- Department of Biochemistry, Graduate School of Medical Sciences, Nagoya City University, Nagoya, Japan
| | - YOSHIHIRO ABIKO
- Division of Oral Medicine and Pathology, Department of Human Biology and Pathophysiology, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Japan
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Dziedzic A. Is Periodontitis Associated with Age-Related Cognitive Impairment? The Systematic Review, Confounders Assessment and Meta-Analysis of Clinical Studies. Int J Mol Sci 2022; 23:15320. [PMID: 36499656 PMCID: PMC9739281 DOI: 10.3390/ijms232315320] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 11/27/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022] Open
Abstract
It has been suggested that molecular pathological mechanisms responsible for periodontitis can be linked with biochemical alterations in neurodegenerative disorders. Hypothetically, chronic systemic inflammation as a response to periodontitis plays a role in the etiology of cognitive impairment. This study aimed to determine whether periodontitis (PDS) is a risk factor for age-related cognitive impairment (ACI) based on evidence of clinical studies. A comprehensive, structured systematic review of existing data adhering to the Preferred Reporting Items for Systematic Review and Meta Analyses (PRISMA) guidelines was carried out. Five electronic databases, PubMed, Embase, Scopus, Web of Science, and Cochrane, were searched for key terms published in peer-reviewed journals until January 2021. The Newcastle-Ottawa scale was used to assess the quality of studies and risk of bias. The primary and residual confounders were explored and evaluated. A meta-analysis synthesizing quantitative data was carried out using a random-effects model. Seventeen clinical studies were identified, including 14 cohort, one cross-sectional, and two case-control studies. Study samples ranged from 85 to 262,349 subjects, with follow-up between 2 and 32 years, and age above 45 years, except for two studies. The findings of studies suggesting the PDS-ACI relationship revealed substantial differences in design and methods. A noticeable variation related to the treatment of confounders was observed. Quality assessment unveiled a moderate quality of evidence and risk of bias. The subgroups meta-analysis and pooled sensitivity analysis of results from seven eligible studies demonstrated overall that the presence of PDS is associated with an increased risk of incidence of cognitive impairment (OR = 1.36, 95% CI 1.03-1.79), particularly dementia (OR = 1.39, 95% CI 1.02-1.88) and Alzheimer's disease (OR = 1.03 95% CI 0.98-1.07)). However, a considerable heterogeneity of synthesized data (I2 = 96%) and potential publication bias might affect obtained results. While there is a moderate statistical association between periodontitis and dementia, as well as Alzheimer's disease, the risk of bias in the evidence prevents conclusions being drawn about the role of periodontitis as a risk factor for age-related cognitive impairment.
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Affiliation(s)
- Arkadiusz Dziedzic
- Department of Conservative Dentistry with Endodontics, Medical University of Silesia, 40-055 Katowice, Poland
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Li X, Kiprowska M, Kansara T, Kansara P, Li P. Neuroinflammation: A Distal Consequence of Periodontitis. J Dent Res 2022; 101:1441-1449. [PMID: 35708472 PMCID: PMC9608094 DOI: 10.1177/00220345221102084] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Periodontitis, a chronic, inflammatory disease, induces systemic inflammation and contributes to the development of neurodegenerative diseases. The precise etiology of the most common neurodegenerative disorders, such as sporadic Alzheimer's, Parkinson's diseases and multiple sclerosis (AD, PD, and MS, respectively), remains to be revealed. Chronic neuroinflammation is a well-recognized component of these disorders, and evidence suggests that systemic inflammation is a possible stimulus for neuroinflammation development. Systemic inflammation can lead to deleterious consequences on the brain if the inflammation is sufficiently severe or if the brain shows vulnerabilities due to genetic predisposition, aging, or neurodegenerative diseases. It has been proposed that periodontal disease can initiate or contribute to the AD pathogenesis through multiple pathways, including key periodontal pathogens. Dysbiotic oral bacteria can release bacterial products into the bloodstream and eventually cross the brain-blood barrier; these bacteria can also cause alterations to gut microbiota that enhance inflammation and potentially affect brain function via the gut-brain axis. The trigeminal nerve has been suggested as another route for connecting oral bacterial products to the brain. PD and MS are often preceded by gastrointestinal symptoms or aberrant gut microbiome composition, and alterations in the enteric nervous system accompany the disease. Clinical evidence has suggested that patients with periodontitis are at a higher risk of developing PD and MS. This nexus among the brain, periodontal disease, and systemic inflammation heralds new ways in which microglial cells, the main innate immune cells, and astrocytes, the crucial regulators of innate and adaptive immune responses in the brain, contribute to brain pathology. Currently, the lack of understanding of the pathogenesis of neurodegeneration is hindering treatment development. However, we may prevent this pathogenesis by tackling one of its possible contributors (periodontitis) for systemic inflammation through simple preventive oral hygiene measures.
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Affiliation(s)
- X. Li
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY, USA
- Department of Urology, New York University Grossman School of Medicine, New York, NY, USA
- Perlmutter Cancer Institute, New York University Langone Medical Center, New York, NY, USA
| | - M. Kiprowska
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY, USA
| | - T. Kansara
- Cleveland Clinic- Union hospital, Dover, OH, USA
| | - P. Kansara
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY, USA
| | - P. Li
- Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY, USA
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Treponema denticola Induces Neuronal Apoptosis by Promoting Amyloid-β Accumulation in Mice. Pathogens 2022; 11:pathogens11101150. [PMID: 36297207 PMCID: PMC9610539 DOI: 10.3390/pathogens11101150] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 09/29/2022] [Accepted: 10/02/2022] [Indexed: 11/13/2022] Open
Abstract
Background: Neuronal apoptosis is a major contributor to Alzheimer's disease (AD). Periodontitis is a significant risk factor for AD. The periodontal pathogens Porphyromonas gingivalis and Treponema denticola have been shown to initiate the hallmark pathologies and behavioral symptoms of AD. Studies have found that T. denticola infection induced Tau hyperphosphorylation and amyloid β accumulation in the hippocampi of mice. Aβ accumulation is closely associated with neuronal apoptosis. However, the roles of T. denticola in neuronal apoptosis remain unclear and its roles in AD pathology need further study. Objective: This study aimed to investigate whether oral infection with T. denticola induced alveolar bone loss and neuronal apoptosis in mice. Methods: C57BL/6 mice were orally administered with T. denticola, Micro-CT was employed to assess the alveolar bone resorption. Western blotting, quantitative PCR, and TUNEL staining were utilized to detect the apoptosis-associated changes in mouse hippocampi. N2a were co-cultured with T. denticola to verify in vivo results. Results: Mice infected with T. denticola exhibited more alveolar bone loss compared with the control mice. T. denticola oral infection induced neuronal apoptosis in hippocampi of mice. Consistent results of the apoptosis-associated protein expression were observed in N2a cells treated with T. denticola and Aβ1-42 in vitro. However, the Aβ inhibitor reversed these results, suggesting that Aβ1-42 mediates T. denticola infection-induced neuronal apoptosis. Conclusions: This study found that oral infected T. denticola caused alveolar bone loss, and induced neuronal apoptosis by promoting Aβ accumulation in mice, providing evidence for the link between periodontitis and AD.
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Kanagasingam S, von Ruhland C, Welbury R, Chukkapalli SS, Singhrao SK. Porphyromonas gingivalis Conditioned Medium Induces Amyloidogenic Processing of the Amyloid-β Protein Precursor upon in vitro Infection of SH-SY5Y Cells. J Alzheimers Dis Rep 2022; 6:577-587. [PMID: 36275415 PMCID: PMC9535609 DOI: 10.3233/adr-220029] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 08/23/2022] [Indexed: 12/27/2022] Open
Abstract
Background: Cleavage of the amyloid-β protein precursor (AβPP) mediated by host secretase enzymes, releases several fragments including amyloid-β (Aβ40 and Aβ42). Objective: To determine if Porphyromonas gingivalis conditioned medium cleaved AβPP to release Aβ40 and Aβ42. Methods: The SH-SY5Y cell line was challenged, in vitro, with P. gingivalis (Pg381) conditioned medium in the presence/absence of cytokines. The cells and their supernatants were assessed for AβPP cleavage fragments by immunoblotting and transmission electron microscopy. Results: Western blotting of the cell lysates with the anti-AβPP C-terminal antibody demonstrated variable molecular weight bands corresponding to full length and fragmented AβPP in lanes treated with the following factors: Tryptic soy broth (TSB), Pg381, IL-6, Pg381 + IL-1β, and Pg381 + TNF-α. The low molecular weight bands corresponding to the C99 dimerized fragment were observed in the Pg381 and interlukin-6 (IL-6) treated groups and were significantly more intense in the presence of Pg381 with either IL-6 or TNF-α. Bands corresponding to the dimerized C83 fragment were observed with cells treated with TNF-α alone and with Pg381 combined with IL-1β or IL-6 or TNF-α. The anti-Aβ antibody detected statistically significant Aβ40 and Aβ42, levels when these two Aβ species were pooled across test samples and compared to the untreated group. Electron microscopic examination of the supernatants demonstrated insoluble Aβ40 and Aβ42. Conclusion: These observations strongly imply that AβPP is an infection responsive protein cleaved via the amyloidogenic pathway on exposure to conditioned medium and in the presence of pro-inflammatory mediators.
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Affiliation(s)
- Shalini Kanagasingam
- Brain and Behavior Centre, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston, UK
| | - Christopher von Ruhland
- Electron and Light Microscopy Facility, College of Biomedical and Life Sciences, Cardiff University, Wales, UK
| | - Richard Welbury
- Brain and Behavior Centre, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston, UK
| | | | - Sim K. Singhrao
- Brain and Behavior Centre, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston, UK
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Yan C, Diao Q, Zhao Y, Zhang C, He X, Huang R, Li Y. Fusobacterium nucleatum infection-induced neurodegeneration and abnormal gut microbiota composition in Alzheimer’s disease-like rats. Front Neurosci 2022; 16:884543. [PMID: 36188448 PMCID: PMC9523129 DOI: 10.3389/fnins.2022.884543] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 07/28/2022] [Indexed: 11/13/2022] Open
Abstract
Objective To explore whether Fusobacterium nucleatum could lead to behavioral and pathological changes in Alzheimer’s disease (AD)-like model rat and whether they could affect the gut microbiota. Methods The cognitive ability and alveolar bone loss of Sprague-Dawley (SD) rats were tested by Morris water maze and Micro-CT, respectively. HE staining and immunohistochemistry were used to analyze the pathological changes and Aβ1–42 in brains. Western blot was applied to detect the expression of p-Tau 181 in the brain. Limulus amebocyte lysate assay and PCR were performed to determine serum LPS level and whether F. nucleatum accessed the brain, respectively. The gut microbiota was analyzed by the 16S rRNA gene sequence. Results Oral infection with F. nucleatum could induce increased alveolar bone loss and learning impairment in AD-like rats. Additionally, F. nucleatum exposure increased the Aβ1–42 expression by about one-fourth (P < 0.05), p-Tau181 by about one-third (P < 0.05), and serum LPS (P < 0.05) in AD-like rats. Moreover, F. nucleatum could change the gut microflora composition in AD-like rats, accompanied by a significant increase in the abundance of Streptococcus and Prevotella. Conclusion Oral infection with F. nucleatum could contribute to abnormalities in cognitive ability and pathological change in the brain of AD-like rats, which may be related to abnormal gut microbiota composition.
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Affiliation(s)
- Caixia Yan
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China
| | - Qilin Diao
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China
| | - Yuxi Zhao
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China
| | - Cheng Zhang
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China
| | - Xiaoya He
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China
| | - Ruijie Huang
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China
- Department of Pediatric Dentistry, State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China
| | - Yan Li
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, National Clinical Research Center for Oral Diseases, Sichuan University, Chengdu, China
- *Correspondence: Yan Li,
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Gong T, Chen Q, Mao H, Zhang Y, Ren H, Xu M, Chen H, Yang D. Outer membrane vesicles of Porphyromonas gingivalis trigger NLRP3 inflammasome and induce neuroinflammation, tau phosphorylation, and memory dysfunction in mice. Front Cell Infect Microbiol 2022; 12:925435. [PMID: 36017373 PMCID: PMC9397999 DOI: 10.3389/fcimb.2022.925435] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 07/01/2022] [Indexed: 11/13/2022] Open
Abstract
BackgroundPorphyromonas gingivalis (Pg), the keystone pathogen in chronic periodontitis, is reported to initiate Alzheimer’s disease pathologies in preclinical studies. However, the specific mechanisms and signaling pathways acting on the brain still need to be further explored. Outer membrane vesicles are derived from Gram-negative bacteria and contain many virulence factors of bacteria. We hypothesized that outer membrane vesicles are an important weapon of Porphyromonas gingivalis to initiate Alzheimer’s disease pathologies.MethodsThe outer membrane vesicles of Porphyromonas gingivalis (Pg OMVs, 4 mg/kg) or saline were delivered to 14-month-old mice by oral gavage every other day for eight weeks. Behavioral alterations were assessed by the open field test, Morris water maze, and Y-maze test. Blood–brain barrier permeability, neuroinflammation, tau phosphorylation, and NLRP3 inflammasome-related protein were analyzed.ResultsPg OMVs impaired memory and learning ability of mice and decreased tight junction–related gene expression ZO-1, occludin, claudin-5, and occludin protein expression in the hippocampus. Pg OMVs could be detected in the hippocampus and cortex three days after oral gavage. Furthermore, Pg OMVs activated both astrocytes and microglia and elevated IL-1β, tau phosphorylation on the Thr231 site, and NLRP3 inflammasome–related protein expression in the hippocampus. In in vitro studies, Pg OMV (5 µg/ml) stimulation increased the mRNA and immunofluorescence of NLRP3 in BV2 microglia, which were significantly inhibited by the NLRP3 inhibitor MCC950. In contrast, the tau phosphorylation in N2a neurons was enhanced after treatment with conditioned media from Pg OMV-stimulated microglia, which was attenuated after pretreatment with MCC950.ConclusionsThese results indicate that Pg OMVs prompt memory dysfunction, neuroinflammation, and tau phosphorylation and trigger NLRP3 inflammasome in the brain of middle-aged mice. We propose that Pg OMVs play an important role in activating neuroinflammation in the AD-like pathology triggered by Porphyromonas gingivalis, and NLRP3 inflammasome activation is a possible mechanism.
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Affiliation(s)
- Ting Gong
- Department of Endodontics, Stomatological Hospital of Chongqing Medical University, Chongqing, China
- Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing Medical University, Chongqing, China
- Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing Medical University, Chongqing, China
| | - Qi Chen
- Department of Endodontics, Stomatological Hospital of Chongqing Medical University, Chongqing, China
- Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing Medical University, Chongqing, China
- Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing Medical University, Chongqing, China
| | - Hongchen Mao
- Department of Endodontics, Stomatological Hospital of Chongqing Medical University, Chongqing, China
- Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing Medical University, Chongqing, China
- Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing Medical University, Chongqing, China
| | - Yao Zhang
- Department of Endodontics, Stomatological Hospital of Chongqing Medical University, Chongqing, China
- Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing Medical University, Chongqing, China
- Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing Medical University, Chongqing, China
| | - Huan Ren
- Department of Endodontics, Stomatological Hospital of Chongqing Medical University, Chongqing, China
- Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing Medical University, Chongqing, China
- Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing Medical University, Chongqing, China
| | - Mengmeng Xu
- Department of Endodontics, Stomatological Hospital of Chongqing Medical University, Chongqing, China
- Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing Medical University, Chongqing, China
- Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing Medical University, Chongqing, China
| | - Hong Chen
- Department of Endodontics, Stomatological Hospital of Chongqing Medical University, Chongqing, China
- Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing Medical University, Chongqing, China
- Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing Medical University, Chongqing, China
| | - Deqin Yang
- Department of Endodontics, Stomatological Hospital of Chongqing Medical University, Chongqing, China
- Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing Medical University, Chongqing, China
- Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing Medical University, Chongqing, China
- *Correspondence: Deqin Yang,
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Landry RL, Embers ME. Does Dementia Have a Microbial Cause? NEUROSCI 2022; 3:262-283. [PMID: 39483362 PMCID: PMC11523730 DOI: 10.3390/neurosci3020019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 05/11/2022] [Indexed: 11/03/2024] Open
Abstract
The potential contribution of pathogenic microbes to dementia-inducing disease is a subject of considerable importance. Alzheimer's disease (AD) is a neurocognitive disease that slowly destroys brain function, leading to cognitive decline and behavioral and psychiatric disorders. The histopathology of AD is associated with neuronal loss and progressive synaptic dysfunction, accompanied by the deposition of amyloid-β (Aβ) peptide in the form of parenchymal plaques and abnormal aggregated tau protein in the form of neurofibrillary tangles. Observational, epidemiological, experimental, and pathological studies have generated evidence for the complexity and possible polymicrobial causality in dementia-inducing diseases. The AD pathogen hypothesis states that pathogens and microbes act as triggers, interacting with genetic factors to initiate the accumulation of Aβ, hyperphosphorylated tau protein (p-tau), and inflammation in the brain. Evidence indicates that Borrelia sp., HSV-1, VZV (HHV-2), HHV-6/7, oral pathogens, Chlamydophila pneumoniae, and Candida albicans can infect the central nervous system (CNS), evade the immune system, and consequently prevail in the AD brain. Researchers have made significant progress in understanding the multifactorial and overlapping factors that are thought to take part in the etiopathogenesis of dementia; however, the cause of AD remains unclear.
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Affiliation(s)
- Remi L Landry
- Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA 70112, USA;
- Division of Immunology, Tulane National Primate Research Center, Tulane University Health Sciences, Covington, LA 70433, USA
| | - Monica E Embers
- Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA 70112, USA;
- Division of Immunology, Tulane National Primate Research Center, Tulane University Health Sciences, Covington, LA 70433, USA
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Harding A, Kanagasingam S, Welbury R, Singhrao SK. Periodontitis as a Risk Factor for Alzheimer's Disease: The Experimental Journey So Far, with Hope of Therapy. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1373:241-260. [PMID: 35612802 DOI: 10.1007/978-3-030-96881-6_13] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Periodontitis and Alzheimer's disease (AD) exist globally within the adult population. Given that the risk of AD incidence doubles within 10 years from the time of periodontal disease diagnosis, there is a window of opportunity for slowing down or preventing AD by risk-reduction-based intervention. Literature appraisal on the shared risk factors of these diseases suggests a shift to a healthy lifestyle would be beneficial. Generalised (chronic) periodontitis with an established dysbiotic polymicrobial aetiology affects the tooth supporting tissues with eventual tooth loss. The cause of AD remains unknown, however two neurohistopathological lesions - amyloid-beta plaques and neurofibrillary tangles, together with the clinical history, provide AD diagnosis at autopsy. Historically, prominence was given to the two hallmark lesions but now emphasis is placed on cerebral inflammation and what triggers it. Low socioeconomic status promotes poor lifestyles that compromise oral and personal hygiene along with reliance on poor dietary intake. Taken together with advancing age and a declining immune protection, these risk factors may negatively impact on periodontitis and AD. These factors also provide a tangible solution to controlling pathogenic bacteria indigenous to the oral and gastrointestinal tract microbioes in vulnerable subjects. The focus here is on Porphyromonas gingivalis, one of several important bacterial pathogens associated with both periodontitis and AD. Recent research has enabled advances in our knowledge of the armoury of P. gingivalis via reproduction of all clinical and neuropathological hallmark lesions of AD and chronic periodontal disease in vitro and in vivo experimental models, thus paving the way for better future management.
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Affiliation(s)
- Alice Harding
- Brain and Behavior Centre, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston, UK
| | - Shalini Kanagasingam
- Brain and Behavior Centre, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston, UK
| | - Richard Welbury
- Brain and Behavior Centre, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston, UK
| | - Sim K Singhrao
- Brain and Behavior Centre, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston, UK.
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43
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Duan L, Qian X, Wang Q, Huang L, Ge S. Experimental Periodontitis Deteriorates Cognitive Function and Impairs Insulin Signaling in a Streptozotocin-Induced Alzheimer’s Disease Rat Model. J Alzheimers Dis 2022; 88:57-74. [PMID: 35527550 DOI: 10.3233/jad-215720] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Background: With advancements in periodontal medicine, the relationship between periodontitis and systemic diseases has garnered increasing attention. Recently, emerging evidence has indicated that periodontitis may be involved in the pathogenesis of Alzheimer’s disease (AD). Objective: To assess the impact of experimental periodontitis on cognitive function deficits in a rat model of streptozotocin-induced AD and determine the mechanisms underlying these effects. Methods: Rats were randomly assigned to the control (C), experimental periodontitis (P), Alzheimer’s disease (AD), and experimental periodontitis with streptozotocin-induced AD (AD-P) groups. Experimental periodontitis was induced using ligation and coating with Porphyromonas gingivalis. In the AD-P group, AD was induced by intracerebroventricular injection of streptozotocin after 6 weeks of experimental periodontitis induction. Results: Compared with the group C rats, those in group P exhibited alveolar bone resorption, learning and memory function impairment, and decreased insulin sensitivity and insulin signaling-related protein expression. Glial cell activation and cognitive impairment in streptozotocin-induced groups with significantly increased phosphorylated tau levels were more pronounced relative to the C group. The number of neurons and insulin sensitivity and insulin signaling-related protein expression in group AD-P rats were lower than those in the AD alone group, while the expressions of glial fibrillary acidic protein, tau phosphorylation, interleukin-6, and cyclooxygenase-2 were significantly increased. Conclusion: Periodontitis may be a risk factor exacerbating cognitive deficits in an AD-like neurodegenerative context, possibly by impairing the insulin signaling pathway and stimulating gliosis and neuroinflammation.
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Affiliation(s)
- Lian Duan
- Hospital of Stomatology, Zunyi Medical University, Zunyi, Guizhou, China
| | - Xueshen Qian
- Hospital of Stomatology, Zunyi Medical University, Zunyi, Guizhou, China
| | - Qin Wang
- Hospital of Stomatology, Zunyi Medical University, Zunyi, Guizhou, China
| | - Lan Huang
- Hospital of Stomatology, Zunyi Medical University, Zunyi, Guizhou, China
| | - Song Ge
- Hospital of Stomatology, Zunyi Medical University, Zunyi, Guizhou, China
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44
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McManus RM. The Role of Immunity in Alzheimer's Disease. Adv Biol (Weinh) 2022; 6:e2101166. [PMID: 35254006 DOI: 10.1002/adbi.202101166] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 02/03/2022] [Indexed: 01/27/2023]
Abstract
With the increase in the aging population, age-related conditions such as dementia and Alzheimer's disease will become ever more prevalent in society. As there is no cure for dementia and extremely limited therapeutic options, researchers are examining the mechanisms that contribute to the progression of cognitive decline in hopes of developing better therapies and even an effective, long-lasting treatment for this devastating condition. This review will provide an updated perspective on the role of immunity in triggering the changes that lead to the development of dementia. It will detail the latest findings on Aβ- and tau-induced microglial activation, including the role of the inflammasome. The contribution of the adaptive immune system, specifically T cells, will be discussed. Finally, whether the innate and adaptive immune system can be modulated to protect against dementia will be examined, along with an assessment of the prospective candidates for these that are currently in clinical trials.
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Affiliation(s)
- Róisín M McManus
- German Center for Neurodegenerative Diseases (DZNE), 53127, Bonn, Germany
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2,3,5,4′-Tetrahydroxystilbene-2-O-β-glucoside Attenuates Reactive Oxygen Species-Dependent Inflammation and Apoptosis in Porphyromonas gingivalis-Infected Brain Endothelial Cells. Antioxidants (Basel) 2022; 11:antiox11040740. [PMID: 35453424 PMCID: PMC9024880 DOI: 10.3390/antiox11040740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 04/01/2022] [Accepted: 04/06/2022] [Indexed: 12/04/2022] Open
Abstract
We recently reported that the periodontopathic bacteria Porphyromonas gingivalis (P. gingivalis) initiates an inflammatory cascade that disrupts the balance of reactive oxygen species (ROS), resulting in apoptotic cell death in brain endothelial cells. An extract from Polygonum multiflorum Thunb., 2,3,5,4′-Tetrahydroxystilbene-2-O-β-glucoside (THSG) has been well-reported to diminish the inflammation in many disease models. However, the effects of THSG in the area of the brain–oral axis is unknown. In this study, we examined the effects of THSG in P. gingivalis-stimulated inflammatory response and apoptotic cell death in brain endothelial cells. THSG treatment remarkably lessened the upregulation of IL-1β and TNF-α proteins in bEnd.3 cells infected with P. gingivalis. Treatment of THSG further ameliorated brain endothelial cell death, including apoptosis caused by P. gingivalis. Moreover, the present study showed that the inhibitory effects on NF-κB p65 and antiapoptotic properties of THSG is through inhibiting the ROS pathway. Importantly, the ROS inhibitory potency of THSG is similar to a ROS scavenger N-Acetyl-L-Cysteine (NAC) and NADPH oxidase inhibitor apocynin. Furthermore, the protective effect of THSG from P. gingivalis infection was further confirmed in primary mouse brain endothelial cells. Taken together, this study indicates that THSG attenuates an ROS-dependent inflammatory response and cell apoptosis in P. gingivalis-infected brain endothelial cells. Our results also suggest that THSG could be a potential herbal medicine to prevent the risk of developing cerebrovascular diseases from infection of periodontal bacteria.
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Bowland GB, Weyrich LS. The Oral-Microbiome-Brain Axis and Neuropsychiatric Disorders: An Anthropological Perspective. Front Psychiatry 2022; 13:810008. [PMID: 35432038 PMCID: PMC9005879 DOI: 10.3389/fpsyt.2022.810008] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 02/14/2022] [Indexed: 12/12/2022] Open
Abstract
In the 21st century, neuropsychiatric disorders (NPDs) are on the rise, yet the causal mechanisms behind this global epidemic remain poorly understood. A key to these unknowns may lie within the vast communities of bacteria, fungi, and viruses in the body (microbiota), which are intimately linked with health and disease. NPDs were recently shown to be connected to gut microbiota, which can communicate with and influence the brain through the Gut-Brain-Axis (GBA). Parallel studies examining oral microbiota and their connections to the brain also suggest that microbes in the mouth can similarly influence NPD outcomes. However, the mechanisms and pathways that illuminate how oral microbiota and brain communicate in NPDs remain unknown. Here, we review identified mechanisms and pathways that oral microbiota use to engage the brain, and we lay the theoretical foundation for an oral-microbiota-brain axis (OMBA). Specifically, we examine established neuroinflammatory and immune system activation responses that underpin interactions between the oral microbiota and the central nervous system (CNS), detailing four specific mechanisms: (1) microbial and metabolite escape, (2) neuroinflammation, (3) CNS signaling, and (4) response to neurohormones. We then scrutinize why including the OMBA, in addition to the GBA, is critically needed to elucidate specific causal relationships between microbial dysbiosis and observed NPD development and progression. Furthermore, we argue for comprehensive, interdisciplinary approaches that integrate lab-based microbiome research and population-level studies that examine the OMBA to improve NPDs. We specifically identify key anthropological perspectives that integrate sociocultural, epidemiological, genetic, and environmental factors that shape the oral microbiome and its interactions with NPDs. Together, future studies of the OMBA in conjunction with interdisciplinary approaches can be used to identify NPD risks and improve outcomes, as well as develop novel intervention and treatment strategies.
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Affiliation(s)
- Grace B. Bowland
- Department of Anthropology, Pennsylvania State University, University Park, PA, United States
| | - Laura S. Weyrich
- Department of Anthropology, Pennsylvania State University, University Park, PA, United States
- Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, United States
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47
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Jungbauer G, Stähli A, Zhu X, Auber Alberi L, Sculean A, Eick S. Periodontal microorganisms and Alzheimer disease - A causative relationship? Periodontol 2000 2022; 89:59-82. [PMID: 35244967 PMCID: PMC9314828 DOI: 10.1111/prd.12429] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 12/07/2021] [Accepted: 12/21/2021] [Indexed: 01/10/2023]
Abstract
In the initiation or exacerbation of Alzheimer disease, the dissemination of oral microorganisms into the brain tissue or the low‐level systemic inflammation have been speculated to play a role. However, the impact of oral microorganisms, such as Porphyromonas gingivalis, on the pathogenesis of Alzheimer disease and the potential causative relationship is still unclear. The present review has critically reviewed the literature by examining the following aspects: (a) the oral microbiome and the immune response in the elderly population, (b) human studies on the association between periodontal and gut microorganisms and Alzheimer disease, (c) animal and in vitro studies on microorganisms and Alzheimer disease, and (d) preventive and therapeutic approaches. Factors contributing to microbial dysbiosis seem to be aging, local inflammation, systemic diseases, wearing of dentures, living in nursing homes and no access to adequate oral hygiene measures. Porphyromonas gingivalis was detectable in post‐mortem brain samples. Microbiome analyses of saliva samples or oral biofilms showed a decreased microbial diversity and a different composition in Alzheimer disease compared to cognitively healthy subjects. Many in‐vitro and animal studies underline the potential of P gingivalis to induce Alzheimer disease‐related alterations. In animal models, recurring applications of P gingivalis or its components increased pro‐inflammatory mediators and β‐amyloid in the brain and deteriorated the animals' cognitive performance. Since periodontitis is the result of a disturbed microbial homoeostasis, an effect of periodontal therapy on the oral microbiome and host response related to cognitive parameters may be suggested and should be elucidated in further clinical trials.
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Affiliation(s)
- Gert Jungbauer
- Department of Periodontology, School of Dental Medicine, University of Bern, Bern, Switzerland.,Private Dental Practice, Straubing, Germany
| | - Alexandra Stähli
- Department of Periodontology, School of Dental Medicine, University of Bern, Bern, Switzerland
| | - Xilei Zhu
- Department of Periodontology, School of Dental Medicine, University of Bern, Bern, Switzerland
| | | | - Anton Sculean
- Department of Periodontology, School of Dental Medicine, University of Bern, Bern, Switzerland
| | - Sigrun Eick
- Department of Periodontology, School of Dental Medicine, University of Bern, Bern, Switzerland
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48
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Nonaka S, Kadowaki T, Nakanishi H. Secreted gingipains from Porphyromonas gingivalis increase permeability in human cerebral microvascular endothelial cells through intracellular degradation of tight junction proteins. Neurochem Int 2022; 154:105282. [PMID: 35032577 DOI: 10.1016/j.neuint.2022.105282] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 12/21/2021] [Accepted: 01/10/2022] [Indexed: 12/14/2022]
Abstract
Despite a clear correlation between the infiltration of periodontal pathogens in the brain and cognitive decline in Alzheimer's disease (AD), the precise mechanism underlying bacteria crossing the blood-brain barrier (BBB) remains unclear. The periodontal pathogen Porphyromonas gingivalis produces a unique class of cysteine proteases termed gingipains. Gingipains appear to be key virulence factors that exacerbate sporadic AD. We herein report that gingipains are involved in increasing permeability of hCMEC/D3 cell monolayer, human cerebral microvascular endothelial cell lines, through degradation of tight junction proteins including zonula occludens (ZO-1) and occludin. There was a significant decrease in the mean protein levels of ZO-1 and occludin after infection of hCMEC/D3 cells with wild-type (WT) P. gingivalis. However, infection of these cells with a gingipain-deficient P. gingivalis strain showed significantly lower reduction of the mean protein levels of either ZO-1 and occludin, compared to the WT strain. Similar results were obtained after treatment with culture supernatant from WT and gingipain-deficient P. gingivalis strains. In vitro digestion of human recombinant ZO-1 and occludin by WT P. gingivalis culture supernatant in the absence or presence of gingipain inhibitors indicated that gingipains directly degraded these tight junction proteins. A close immunohistochemical examination using anti-gingipain antibody further revealed that gingipains localized in the cytosol and nuclei of hCMEC/D3 cells after infection with WT P. gingivalis and treatment with its culture supernatant. Furthermore, intracellular localization of outer membrane vesicles (OMVs) bound gingipains from WT P. gingivalis and OMV-induced degradation of ZO-1 and occludin were also observed in hCMEC/D3 cells. Thus, the delivery of gingipains into the cerebral microvascular endothelial cells, probably through OMV, may be responsible for the BBB damage through intracellular degradation of ZO-1 and occludin.
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Affiliation(s)
- Saori Nonaka
- Department of Pharmacology, Faculty of Pharmacy, Yasuda Women's University, Hiroshima, 731-0153, Japan.
| | - Tomoko Kadowaki
- Department of Frontier Oral Science, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, 852-8588, Japan
| | - Hiroshi Nakanishi
- Department of Pharmacology, Faculty of Pharmacy, Yasuda Women's University, Hiroshima, 731-0153, Japan.
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Chouhan JK, Püntener U, Booth SG, Teeling JL. Systemic Inflammation Accelerates Changes in Microglial and Synaptic Markers in an Experimental Model of Chronic Neurodegeneration. Front Neurosci 2022; 15:760721. [PMID: 35058740 PMCID: PMC8764443 DOI: 10.3389/fnins.2021.760721] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 11/30/2021] [Indexed: 12/01/2022] Open
Abstract
Bacterial infections are a common cause of morbidity and mortality in the elderly, and particularly in individuals with a neurodegenerative disease. Experimental models of neurodegeneration have shown that LPS-induced systemic inflammation increases neuronal damage, a process thought to be mediated by activation of "primed" microglia. The effects of a real systemic bacterial infection on the innate immune cells in the brain and neuronal networks are less well described, and therefore, in this study we use the ME7 prion model to investigate the alterations in microglia activation and phenotype and synaptic markers in response to a low grade, live bacterial infection. Mice with or without a pre-existing ME7 prion-induced neurodegenerative disease were given a single systemic injection of live Salmonella typhimurium at early or mid-stage of disease progression. Immune activation markers CD11b and MHCII and pro-inflammatory cytokines were analyzed 4 weeks post-infection. Systemic infection with S. typhimurium resulted in an exaggerated inflammatory response when compared to ME7 prion mice treated with saline. These changes to inflammatory markers were most pronounced at mid-stage disease. Analysis of synaptic markers in ME7 prion mice revealed a significant reduction of genes that are associated with early response in synaptic plasticity, extracellular matrix structure and post-synaptic density, but no further reduction following systemic infection. In contrast, analysis of activity-related neuronal receptors involved in development of learning and memory, such as Grm1 and Grin2a, showed a significant decrease in response to systemic bacterial challenge. These changes were observed early in the disease progression and associated with reduced burrowing activity. The exaggerated innate immune activation and altered expression of genes linked to synaptic plasticity may contribute to the onset and/or progression of neurodegeneration.
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Affiliation(s)
| | | | | | - Jessica L. Teeling
- Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Southampton, United Kingdom
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50
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Tadjoedin FM, Masulili SLC, Rizal MI, Kusdhany LS, Turana Y, Ismail RI, Bachtiar BM. The Red and Orange Complex Subgingival Microbiome of Cognitive Impairment and Cognitively Normal Elderly with Periodontitis. Geriatrics (Basel) 2022; 7:geriatrics7010012. [PMID: 35076522 PMCID: PMC8788293 DOI: 10.3390/geriatrics7010012] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 12/28/2021] [Accepted: 12/31/2021] [Indexed: 12/03/2022] Open
Abstract
Increasing evidence has shown an association between periodontitis and cognitive impairment. Subgingival microbiota play a great role in periodontitis pathogenesis. However, the correlation between the subgingival microbiome and cognitive impairment remains unclear. This study aimed to evaluate the red and orange complex subgingival microbiome of cognitively impaired and cognitively normal elderly Indonesian subjects with periodontitis. Twenty-eight elderly subjects diagnosed with periodontitis underwent two cognitive examinations using the Hopkins Verbal Learning Test and the Mini-Mental State Examination. Gingival crevicular fluid taken from the periodontal pocket, at a depth between 5 and 7 mm, using a paper point was used as the subgingival samples. The subgingival microbiome in the cognitive impairment group (n = 14) and cognitively normal group (n = 14) was compared using the 16S rRNA Metagenomic iSeq™ 100 Sequencing System. There was β-diversity in the subgingival microbiota between the cognitively impaired and cognitively normal subjects. The metagenomic analysis showed a higher abundance of Porphyromonas and Treponema bacteria in the cognitive impairment group than in the normal cognitive group (p < 0.05). The abundance of Porphyromonas gingivalis and Treponema denticola was higher in the cognitively impaired elderly subjects. The role of P. gingivalis and T. denticola in the pathogenesis of cognitive impairment needs further investigation.
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Affiliation(s)
- Fatimah Maria Tadjoedin
- Doctoral Program, Faculty of Dentistry, Universitas Indonesia, Jakarta 10430, Indonesia; (F.M.T.); (M.I.R.)
- Department of Periodontics, Faculty of Dentistry, Universitas Indonesia, Jakarta 10430, Indonesia
| | - Sri Lelyati C. Masulili
- Department of Periodontics, Faculty of Dentistry, Universitas Indonesia, Jakarta 10430, Indonesia
- Correspondence:
| | - Muhammad Ihsan Rizal
- Doctoral Program, Faculty of Dentistry, Universitas Indonesia, Jakarta 10430, Indonesia; (F.M.T.); (M.I.R.)
- Department of Oral Biology, Faculty of Dentistry, Trisakti University, Jakarta 11440, Indonesia
| | - Lindawati S. Kusdhany
- Department of Prosthodontics, Faculty of Dentistry, Universitas Indonesia, Jakarta 10430, Indonesia;
| | - Yuda Turana
- Department of Neurology, School of Medicine and Health Sciences, Atma Jaya Catholic University of Indonesia, Jakarta 14440, Indonesia;
| | - Raden Irawati Ismail
- Department of Psychiatry, Faculty of Medicine Universitas Indonesia—Cipto Mangunkusumo General Hospital, Jakarta 10430, Indonesia;
| | - Boy M. Bachtiar
- Department of Oral Biology, Faculty of Dentistry, Universitas Indonesia, Jakarta 10430, Indonesia;
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