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Chen L, Li X, Liu J, Hou Z, Wei Y, Chen M, Wang B, Cao H, Qiu R, Zhang Y, Ji X, Zhang P, Xue M, Qiu L, Wang L, Li H. Distinctive subgingival microbial signatures in older adults with different levels of cognitive function. J Clin Periodontol 2024; 51:1066-1080. [PMID: 38769711 DOI: 10.1111/jcpe.13997] [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: 11/25/2023] [Revised: 04/19/2024] [Accepted: 04/22/2024] [Indexed: 05/22/2024]
Abstract
AIM To examine association between subgingival microbial signatures and levels of cognitive impairment in older adults. MATERIALS AND METHODS We analysed subgingival plaque samples and 16S ribosomal RNA sequences for microbiota among 165 participants (normal controls [NCs]: 40, subjective cognitive decline [SCD]: 40, mild cognitive impairment [MCI]: 49 and dementia: 36). RESULTS The bacterial richness was lower among individuals with worse cognitive function, and subgingival microbial communities differed significantly among the four groups. Declining cognitive function was associated with decreasing relative abundance of genera Capnocytophaga, Saccharibacteria_genera_incertae_sedis, Lautropia and Granulicatella, and increasing abundance of genus Porphyromonas. Moreover, there were differentially abundant genera among the groups. Random forest model based on subgingival microbiota could distinguish between cognitive impairment and NC (AUC = 0.933, 95% confidence interval 0.873-0.992). Significant correlations were observed between oral microbiota and sex, Montreal Cognitive Assessment (MoCA) score and Mini-Mental State Examination score. Partial correlation analysis showed that Leptotrichia and Burkholderia were closely negatively associated with the MoCA score after adjusting for multiple covariates. Gene function was not significantly different between SCD and NC groups, whereas three homozygous genes were altered in MCI patients and two in dementia patients. CONCLUSIONS This is the first study to demonstrate an association between the composition, function and metabolic pathways of subgingival microbiota and different levels of cognitive function among older individuals. Future cohort studies should assess its diagnostic usefulness for cognitive impairment.
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Affiliation(s)
- Lili Chen
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, Fuzhou, China
- Department of Nursing, Fujian Provincial Hospital, Fuzhou, China
| | - Xiuli Li
- The School of Nursing, Fujian Medical University, Fuzhou, China
| | - Jinxiu Liu
- The School of Nursing, Fujian Medical University, Fuzhou, China
| | - Zhaoyi Hou
- The School of Nursing, Fujian Medical University, Fuzhou, China
| | - Yongbao Wei
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, Fuzhou, China
| | - Mingfeng Chen
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, Fuzhou, China
| | - Bixia Wang
- The School of Nursing, Fujian Medical University, Fuzhou, China
| | - Huizhen Cao
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, Fuzhou, China
| | - Rongyan Qiu
- Department of Surgery, Fujian Provincial Governmental Hospital, Fuzhou, China
| | - Yuping Zhang
- The School of Nursing, Fujian Medical University, Fuzhou, China
| | - Xinli Ji
- The School of Nursing, Fujian Medical University, Fuzhou, China
| | - Ping Zhang
- The School of Nursing, Fujian Medical University, Fuzhou, China
| | - Mianxiang Xue
- The School of Nursing, Fujian Medical University, Fuzhou, China
| | - Linlin Qiu
- The School of Nursing, Fujian Medical University, Fuzhou, China
| | - Linlin Wang
- The School of Nursing, Fujian Medical University, Fuzhou, China
| | - Hong Li
- The School of Nursing, Fujian Medical University, Fuzhou, China
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Yang J, Zhi W, Wang L. Role of Tau Protein in Neurodegenerative Diseases and Development of Its Targeted Drugs: A Literature Review. Molecules 2024; 29:2812. [PMID: 38930877 PMCID: PMC11206543 DOI: 10.3390/molecules29122812] [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: 04/26/2024] [Revised: 06/07/2024] [Accepted: 06/08/2024] [Indexed: 06/28/2024] Open
Abstract
Tau protein is a microtubule-associated protein that is widely distributed in the central nervous system and maintains and regulates neuronal morphology and function. Tau protein aggregates abnormally and forms neurofibrillary tangles in neurodegenerative diseases, disrupting the structure and function of neurons and leading to neuronal death, which triggers the initiation and progression of neurological disorders. The aggregation of tau protein in neurodegenerative diseases is associated with post-translational modifications, which may affect the hydrophilicity, spatial conformation, and stability of tau protein, promoting tau protein aggregation and the formation of neurofibrillary tangles. Therefore, studying the role of tau protein in neurodegenerative diseases and the mechanism of aberrant aggregation is important for understanding the mechanism of neurodegenerative diseases and finding therapeutic approaches. This review describes the possible mechanisms by which tau protein promotes neurodegenerative diseases, the post-translational modifications of tau protein and associated influencing factors, and the current status of drug discovery and development related to tau protein, which may contribute to the development of new therapeutic approaches to alleviate or treat neurodegenerative diseases.
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Affiliation(s)
- Jiakai Yang
- Graduate Collaborative Training Base of Academy of Military Medical Sciences, Hengyang Medical School, University of South China, Hengyang 421001, China;
- Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850, China
| | - Weijia Zhi
- Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850, China
| | - Lifeng Wang
- Graduate Collaborative Training Base of Academy of Military Medical Sciences, Hengyang Medical School, University of South China, Hengyang 421001, China;
- Beijing Institute of Radiation Medicine, 27 Taiping Road, Beijing 100850, China
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3
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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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Yoshida K, Yoshida K, Seyama M, Hiroshima Y, Mekata M, Fujiwara N, Kudo Y, Ozaki K. Porphyromonas gingivalis outer membrane vesicles in cerebral ventricles activate microglia in mice. Oral Dis 2023; 29:3688-3697. [PMID: 36266256 DOI: 10.1111/odi.14413] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 10/10/2022] [Accepted: 10/18/2022] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Porphyromonas gingivalis (Pg) is thought to be involved in the progression of Alzheimer's disease (AD). Whether Pg or its contents can reach the brain and directly affect neuropathology is, however, unknown. Here, we investigated whether outer membrane vesicles (OMVs) of Pg translocate to the brain and induce the pathogenic features of AD. MATERIAL AND METHODS Pg OMVs were injected into the abdominal cavity of mice for 12 weeks. Pg OMV translocation to the brain was detected by immunohistochemistry using an anti-gingipain antibody. Tau protein and microglial activation in the mouse brain were examined by western blotting and immunohistochemistry. The effect of gingipains on inflammation was assessed by real-time polymerase chain reaction using human microglial HMC3 cells. RESULTS Gingipains were detected in the region around cerebral ventricles, choroid plexus, and ventricular ependymal cells in Pg OMV-administered mice. Tau and phosphorylated Tau protein increased and microglia were activated. Pg OMVs also increased the gene expression of proinflammatory cytokines in HMC3 cells in a gingipain-dependent manner. CONCLUSION Pg OMVs, including gingipains, can reach the cerebral ventricle and induce neuroinflammation by activating microglia. Pg OMVs may provide a better understanding of the implications of periodontal diseases in neurodegenerative conditions such as AD.
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Affiliation(s)
- Kayo Yoshida
- Department of Oral Healthcare Promotion, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Kaya Yoshida
- Department of Oral Healthcare Education, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Mariko Seyama
- Department of Oral Healthcare Promotion, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Yuka Hiroshima
- Department of Oral Microbiology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Mana Mekata
- Department of Oral Healthcare Promotion, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Natsumi Fujiwara
- Department of Oral Healthcare Promotion, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Yasusei Kudo
- Department of Oral Bioscience, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Kazumi Ozaki
- Department of Oral Healthcare Promotion, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
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5
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Predicting Key Genes and Therapeutic Molecular Modelling to Explain the Association between Porphyromonas gingivalis (P. gingivalis) and Alzheimer’s Disease (AD). Int J Mol Sci 2023; 24:ijms24065432. [PMID: 36982508 PMCID: PMC10049565 DOI: 10.3390/ijms24065432] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 03/01/2023] [Accepted: 03/03/2023] [Indexed: 03/14/2023] Open
Abstract
The association between Porphyromonas gingivalis (P. gingivalis) and Alzheimer’s disease (AD) remains unclear. The major aim of this study was to elucidate the role of genes and molecular targets in P. gingivalis-associated AD. Two Gene Expression Omnibus (GEO) datasets, GSE5281 for AD (n = 84 Alzheimer’s, n = 74 control) and GSE9723 (n = 4 P. gingivalis, n = 4 control), were downloaded from the GEO database. Differentially expressed genes (DEGs) were obtained, and genes common to both diseases were drawn. Additionally, Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analysis was performed from the top 100 genes (50 upregulated and 50 downregulated genes). We then proceeded with CMap analysis to screen for possible small drug molecules targeting these genes. Subsequently, we performed molecular dynamics simulations. A total of 10 common genes (CALD1, HES1, ID3, PLK2, PPP2R2D, RASGRF1, SUN1, VPS33B, WTH3DI/RAB6A, and ZFP36L1) were identified with a p-value < 0.05. The PPI network of the top 100 genes showed UCHL1, SST, CHGB, CALY, and INA to be common in the MCC, DMNC, and MNC domains. Out of the 10 common genes identified, only 1 was mapped in CMap. We found three candidate small drug molecules to be a fit for PLK2, namely PubChem ID: 24971422, 11364421, and 49792852. We then performed molecular docking of PLK2 with PubChem ID: 24971422, 11364421, and 49792852. The best target, 11364421, was used to conduct the molecular dynamics simulations. The results of this study unravel novel genes to P. gingivalis-associated AD that warrant further validation.
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Weaver DF. Alzheimer's disease as an innate autoimmune disease (AD 2): A new molecular paradigm. Alzheimers Dement 2023; 19:1086-1098. [PMID: 36165334 DOI: 10.1002/alz.12789] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 07/13/2022] [Accepted: 08/09/2022] [Indexed: 11/07/2022]
Abstract
A new model of Alzheimer's disease (AD) is presented: Alzheimer's disease as an autoimmune disease (AD2). In response to pathogen-/damage-associated molecular pattern-stimulating events (e.g., infection, trauma, ischemia, pollution), amyloid beta (Aβ) is released as an early responder cytokine triggering an innate immunity cascade in which Aβ exhibits immunomodulatory/antimicrobial duality. However, Aβ's antimicrobial properties result in a misdirected attack upon "self" neurons, arising from the electrophysiological similarities between neurons and bacteria in terms of transmembrane potential gradients and anionic charges on outer membrane macromolecules. The subsequent breakdown products of necrotic neurons elicit further release of Aβ leading to a chronic, self-perpetuating cycle. In AD2, amino acid (trp, arg) metabolism is a central control player in modulating AD autoimmunity. AD2 includes Aβ as an important molecular player, but rejects the "amyloid hypothesis," recognizing Aβ as a physiologically oligomerizing cytokine and part of a larger immunopathic conceptualization of AD.
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Affiliation(s)
- Donald F Weaver
- Krembil Brain Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada
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7
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Inoue E, Minatozaki S, Katsuta Y, Nonaka S, Nakanishi H. Human β-Defensin 3 Inhibits Porphyromonas Gingivalis Lipopolysaccharide-Induced Oxidative and Inflammatory Responses of Microglia by Suppression of Cathepsins B and L. Int J Mol Sci 2022; 23:ijms232315099. [PMID: 36499428 PMCID: PMC9738813 DOI: 10.3390/ijms232315099] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/25/2022] [Accepted: 11/29/2022] [Indexed: 12/03/2022] Open
Abstract
Recently, the effects of antibacterial peptides are suggested to have therapeutic potential in Alzheimer's disease. Furthermore, systemic treatment of Porphyromonas gingivalis (Pg) lipopolysaccharide (LPS) induced Alzheimer's disease-like neuropathological changes in middle-aged mice. Then, we examined whether human β-defensins (hBDs), antimicrobial peptides produced by the oral mucosa and salivary glands, can suppress Pg LPS-induced oxidative and inflammatory responses by microglia. hBD3 (1 μM) significantly suppressed Pg LPS-induced production of nitric oxide and interleukin-6 (IL-6) by MG6 cells, a mouse microglial cell line. hBD3 (1 μM) also significantly inhibited Pg LPS-induced expression of IL-6 by HMC3 cells, a human microglial cell line. In contrast, neither hBD1, hBD2 nor hBD4 failed to inhibit their productions. Furthermore, hBD3 suppressed Pg LPS-induced p65 nuclear translocation through the IκBα degradation. Pg LPS-induced expression of IL-6 was significantly suppressed by E64d, a cysteine protease inhibitor, and CA-074Me, a known specific inhibitor for cathepsin B, but not by pepstatin A, an aspartic protease inhibitor. Interestingly, hBD3 significantly inhibited enzymatic activities of recombinant human cathepsins B and L, lysosomal cysteine proteases, and their intracellular activities in MG6 cells. Therefore, hBD3 suppressed oxidative and inflammatory responses of microglia through the inhibition of cathepsins B and L, which enzymatic activities are necessary for the NF-κB activation.
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Affiliation(s)
- Erika Inoue
- Faculty of Pharmacy, Yasuda Women’s University, Hiroshima 731-0153, Japan
| | - Shiyo Minatozaki
- Faculty of Pharmacy, Yasuda Women’s University, Hiroshima 731-0153, Japan
| | - Yui Katsuta
- Faculty of Pharmacy, Yasuda Women’s University, Hiroshima 731-0153, Japan
| | - Saori Nonaka
- Department of Pharmacology, Faculty of Pharmacy, Yasuda Women’s University, Hiroshima 731-0153, Japan
| | - Hiroshi Nakanishi
- Department of Pharmacology, Faculty of Pharmacy, Yasuda Women’s University, Hiroshima 731-0153, Japan
- Correspondence:
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Lin J, Huang D, Xu H, Zhan F, Tan X. Macrophages: A communication network linking Porphyromonas gingivalis infection and associated systemic diseases. Front Immunol 2022; 13:952040. [PMID: 35967399 PMCID: PMC9363567 DOI: 10.3389/fimmu.2022.952040] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 06/30/2022] [Indexed: 12/03/2022] Open
Abstract
Porphyromonas gingivalis (P. gingivalis) is a Gram-negative anaerobic pathogen that is involved in the pathogenesis of periodontitis and systemic diseases. P. gingivalis has recently been detected in rheumatoid arthritis (RA), cardiovascular disease, and tumors, as well as Alzheimer’s disease (AD), and the presence of P. gingivalis in these diseases are correlated with poor prognosis. Macrophages are major innate immune cells which modulate immune responses against pathogens, however, multiple bacteria have evolved abilities to evade or even subvert the macrophages’ immune response, in which subsequently promote the diseases’ initiation and progression. P. gingivalis as a keystone pathogen of periodontitis has received increasing attention for the onset and development of systemic diseases. P. gingivalis induces macrophage polarization and inflammasome activation. It also causes immune response evasion which plays important roles in promoting inflammatory diseases, autoimmune diseases, and tumor development. In this review, we summarize recent discoveries on the interaction of P. gingivalis and macrophages in relevant disease development and progression, such as periodontitis, atherosclerosis, RA, AD, and cancers, aiming to provide an in-depth mechanistic understanding of this interaction and potential therapeutic strategies.
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Affiliation(s)
- Jie Lin
- State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Diseases and Department of Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Dingming Huang
- State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Diseases and Department of Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Hongwei Xu
- Myeloma Center, Winthrop P. Rockefeller Cancer Institute, Department of Internal Medicine, University of Arkansas for Medical Sciences (UAMS), Little Rock, AR, United States
| | - Fenghuang Zhan
- Myeloma Center, Winthrop P. Rockefeller Cancer Institute, Department of Internal Medicine, University of Arkansas for Medical Sciences (UAMS), Little Rock, AR, United States
- Division of Hematology and Oncology, Department of Internal Medicine, University of Iowa, Iowa, IA, United States
- *Correspondence: XueLian Tan, ; Fenghuang Zhan,
| | - XueLian Tan
- State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Diseases and Department of Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
- *Correspondence: XueLian Tan, ; Fenghuang Zhan,
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9
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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: 1.5] [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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10
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李 语, 刘 媛, 陈 峰, 初 明, 陈 霄. [Relationship between Oral Microbiota and Alzheimer's Disease]. SICHUAN DA XUE XUE BAO. YI XUE BAN = JOURNAL OF SICHUAN UNIVERSITY. MEDICAL SCIENCE EDITION 2022; 53:194-200. [PMID: 35332717 PMCID: PMC10409350 DOI: 10.12182/20220360304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Accepted: 02/21/2022] [Indexed: 06/14/2023]
Abstract
Alzheimer's disease (AD) is a common neurodegenerative disease. In an aging society, the high prevalence of AD and the low quality of life of AD patients create serious problems for individuals, families and the society. However, the etiology and pathogenesis of AD are still not fully understood. Age, genetics, environment and other factors are all relevant to AD, and treatment has not achieved satisfactory results. Recent studies have found that oral dysbiosis is closely related to the pathogenesis of AD, and that oral bacterial infection may be one of the causes of AD. Oral cavity is the largest microbial ecosystem of human body, and its homeostasis is critical to health. Bacterial infections caused by oral dysbiosis can directly and indirectly induce the metabolic imbalance of amyloid β-protein (Aβ) in the brain and the hyperphosphorylation of Tau protein. Then, the precipitation forms senile plaques and neurofibrillary tangles (NFTs) that damage neurons. Based on the latest research findings, we herein discussed the correlation between oral microbiota and the pathogenesis of AD and the mechanisms involved, as well as the pathogenic mechanism of main oral bacteria. In addition, we explored the potential application prospects of oral microbiota-targeted therapy.
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Affiliation(s)
- 语晨 李
- 北京大学口腔医学院 中心实验室 (北京 100081)Central Laboratory, School of Stomatology, Peking University, Beijing 100081, China
| | - 媛 刘
- 北京大学口腔医学院 中心实验室 (北京 100081)Central Laboratory, School of Stomatology, Peking University, Beijing 100081, China
| | - 峰 陈
- 北京大学口腔医学院 中心实验室 (北京 100081)Central Laboratory, School of Stomatology, Peking University, Beijing 100081, China
| | - 明 初
- 北京大学口腔医学院 中心实验室 (北京 100081)Central Laboratory, School of Stomatology, Peking University, Beijing 100081, China
| | - 霄迟 陈
- 北京大学口腔医学院 中心实验室 (北京 100081)Central Laboratory, School of Stomatology, Peking University, Beijing 100081, China
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11
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Olsen I. Porphyromonas gingivalis-Induced Neuroinflammation in Alzheimer's Disease. Front Neurosci 2021; 15:691016. [PMID: 34720846 PMCID: PMC8551391 DOI: 10.3389/fnins.2021.691016] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 08/27/2021] [Indexed: 11/13/2022] Open
Abstract
"Chronic" periodontitis and its keystone pathogen Porphyromonas gingivalis have repeatedly been associated with Alzheimer's disease (AD). Pathological hallmarks in AD are brain accumulations of amyloid-beta and neurofibrillary tangles consisting of aggregated and hyperphosphorylated tau. In addition, neuroinflammation induced by P. gingivalis has increasingly been recognized as a factor in the pathogenesis of AD. The present mini-review discusses possible mechanisms for the induction of neuroinflammation by P. gingivalis in AD, involving factors such as pro-inflammatory mediators, amyloid-beta, tau, microglia, cathepsin B, and protein kinase R. Inflammagens of P. gingivalis such as lipopolysaccharide and gingipains are also discussed.
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Affiliation(s)
- Ingar Olsen
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
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12
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Natale G, Clouston S, Smith D. Elevated C-Reactive Protein in Alzheimer's Disease without Depression in Older Adults: Findings from the Health and Retirement Study. J Gerontol A Biol Sci Med Sci 2021; 77:673-682. [PMID: 34671810 DOI: 10.1093/gerona/glab282] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Indexed: 11/14/2022] Open
Abstract
We examined the association between differential diagnoses of major stroke and probable Alzheimer's disease (AD) and Mixed AD on c-reactive protein (CRP) in older adults with and without depression. Secondary data analyses examined associations between blood-based measures of probable peripheral inflammation using CRP collected from dried blood spots in the Health and Retirement Study (HRS), a nationally representative sample of individuals aged 50 and older. A validated pattern recognition algorithm was utilized to identify cognitive decline indicative of probable AD, Mixed AD, and major stroke. Negative binomial regressions were utilized to model concentrations of serologic CRP. On average, participants (N=4,601) were 70 years old, female, and non-Hispanic white. Mixed AD participants had 0.26 mg/dL increase in CRP compared to unimpaired participants, controlling for demographics, health behaviors and comorbidities. Those with Mixed AD had 2.14 times increased odds of having high CRP (OR=2.14; [1.19-3.85]). In analyses stratified by depression, adults with Mixed AD and without depression had an additional 0.37 mg/dL increase in CRP (SE=0.06; p<0.001) compared to unimpaired adults. Those with AD without depression had an 0.20 mg/dL increase in CRP (SE=0.07; p<0.01). Age was not associated with increased CRP in non-depressed older adults. Depressed adults with major stroke had a -0.26 mg/dL decrease in CRP (SE=0.11; p=0.02), controlling for hypertension, alcoholic drinks/beverages per week and smoking status. Concentration modeling revealed that participants with major stroke, probable AD and probable mixed AD without depression had significantly higher CRP concentrations when compared to unimpaired older adults.
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Affiliation(s)
- Ginny Natale
- Program in Public Health and Department of Family, Population, and Preventive Medicine, Stony Brook University, Stony Brook, NY, USA
| | - Sean Clouston
- Program in Public Health and Department of Family, Population, and Preventive Medicine, Stony Brook University, Stony Brook, NY, USA
| | - Dylan Smith
- Program in Public Health and Department of Family, Population, and Preventive Medicine, Stony Brook University, Stony Brook, NY, USA
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13
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Olsen I. Can Porphyromonas gingivalis Contribute to Alzheimer's Disease Already at the Stage of Gingivitis? J Alzheimers Dis Rep 2021; 5:237-241. [PMID: 34113781 PMCID: PMC8150255 DOI: 10.3233/adr-210006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Alzheimer's disease (AD) has been associated with periodontitis, which starts as gingivitis. Similar to periodontitis, gingivitis bacteria, bacterial products, and inflammatory mediators can travel to the brain via the blood stream and promote brain inflammation. Periodontal pathogens such as Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, both associated with AD, have been found in dental plaque of children already at the age of 3. It is suggested that these bacteria during long-term exposure may drive microglia (brain resident macrophage cells) into a pro-inflammatory M1 phase where they contribute to AD rather than protect against it. This notion comes from studies in mice showing that microglia actually can "remember" previous inflammatory challenge and become "trained" or "tolerant" to toxins like lipopolysaccharide. If gingivitis has an impact on AD, which should be verified, AD prophylaxis should start already at this pre-periodontitis stage with removal of supragingival plaque.
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Affiliation(s)
- Ingar Olsen
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
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14
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Olsen I. Porphyromonas Gingivalis May Seek the Alzheimer's Disease Brain to Acquire Iron from Its Surplus. J Alzheimers Dis Rep 2021; 5:79-86. [PMID: 33681719 PMCID: PMC7903007 DOI: 10.3233/adr-200272] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Iron accumulates in the brain of subjects with Alzheimer’s disease (AD). Here it promotes the aggregation of amyloid-β plaques in which it is abundant. Iron induces amyloid-β neurotoxicity by damaging free radicals and causing oxidative stress in brain areas with neurodegeneration. It can also bind to tau in AD and enhance the toxicity of tau through co-localization with neurofibrillary tangles and induce accumulation of these tangles. Porphyromonas gingivalis is a key oral pathogen in the widespread biofilm-induced disease “chronic” periodontitis, and recently, has been suggested to have an important role in the pathogenesis of AD. P. gingivalis has an obligate requirement for iron. The current paper suggests that P. gingivalis seeks the AD brain, where it has been identified, to satisfy this need. If this is correct, iron chelators binding iron could have beneficial effects in the treatment of AD. Indeed, studies from both animal AD models and humans with AD have indicated that iron chelators, e.g., lactoferrin, can have such effects. Lactoferrin can also inhibit P. gingivalis growth and proteinases and its ability to form biofilm.
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Affiliation(s)
- Ingar Olsen
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway
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15
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Kanagasingam S, Chukkapalli SS, Welbury R, Singhrao SK. Porphyromonas gingivalis is a Strong Risk Factor for Alzheimer's Disease. J Alzheimers Dis Rep 2020; 4:501-511. [PMID: 33532698 PMCID: PMC7835991 DOI: 10.3233/adr-200250] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Porphyromonas gingivalis (P. gingivalis) is one of the several important bacterial pathogens associated with the sporadic Alzheimer’s disease (AD). Different serotypes are either capsulated or are non-capsulated. It has been demonstrated that P. gingivalis (non-capsulated) can reproduce the neurodegenerative AD-like changes in vitro, and a capsular P. gingivalis (strain W83) could reproduce the cardinal hallmark lesions of AD in a wild-type mouse model. All P. gingivalis forms express proteolytically active proteases that enable cleavage of the amyloid-β protin precursor (AβPP) and tau resulting in the formation of amyloid-β and neurofibrillary tangles. Tau is an established substrate for gingipains, which can cleave tau into various peptides. Some of the P. gingivalis fragmented tau protein peptides contain “VQIINK” and “VQIVYK” hexapeptide motifs which map to the flanking regions of the microtubule binding domains and are also found in paired helical filaments that form NFTs. P. gingivalis can induce peripheral inflammation in periodontitis and can also initiate signaling pathways that activate kinases, which in turn, phosphorylate neuronal tau. Periodontal disease related inflammation has metabolic implications for an individual’s peripheral and brain health as patients suffering from generalized periodontitis often have related co-morbidities and are “at risk” of developing AD. The aim here is to discuss the role of P. gingivalis behind such associations with the backdrop of huge efforts to test P. gingivalis virulence factors clinically (GAIN Trial: Phase 2/3 Study of COR388 in Subjects with AD) with inhibitors, which may lead to an intervention by reducing the pathogenic bacterial load.
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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
| | - Sasanka S Chukkapalli
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - 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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16
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Mei F, Xie M, Huang X, Long Y, Lu X, Wang X, Chen L. Porphyromonas gingivalis and Its Systemic Impact: Current Status. Pathogens 2020; 9:pathogens9110944. [PMID: 33202751 PMCID: PMC7696708 DOI: 10.3390/pathogens9110944] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 10/24/2020] [Accepted: 11/03/2020] [Indexed: 02/06/2023] Open
Abstract
The relationship between periodontitis and systemic diseases, notably including atherosclerosis and diabetes, has been studied for several years. Porphyromonas gingivalis, a prominent component of oral microorganism communities, is the main pathogen that causes periodontitis. As a result of the extensive analysis of this organism, the evidence of its connection to systemic diseases has become more apparent over the last decade. A significant amount of research has explored the role of Porphyromonas gingivalis in atherosclerosis, Alzheimer's disease, rheumatoid arthritis, diabetes, and adverse pregnancy outcomes, while relatively few studies have examined its contribution to respiratory diseases, nonalcoholic fatty liver disease, and depression. Here, we provide an overview of the current state of knowledge about Porphyromonas gingivalis and its systemic impact in an aim to inform readers of the existing epidemiological evidence and the most recent preclinical studies. Additionally, the possible mechanisms by which Porphyromonas gingivalis is involved in the onset or exacerbation of diseases, together with its effects on systemic health, are covered. Although a few results remain controversial, it is now evident that Porphyromonas gingivalis should be regarded as a modifiable factor for several diseases.
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Affiliation(s)
- Feng Mei
- Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; (F.M.); (M.X.); (X.H.); (Y.L.); (X.L.)
- Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, Wuhan 430022, China
| | - Mengru Xie
- Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; (F.M.); (M.X.); (X.H.); (Y.L.); (X.L.)
- Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, Wuhan 430022, China
| | - Xiaofei Huang
- Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; (F.M.); (M.X.); (X.H.); (Y.L.); (X.L.)
- Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, Wuhan 430022, China
| | - Yanlin Long
- Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; (F.M.); (M.X.); (X.H.); (Y.L.); (X.L.)
- Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, Wuhan 430022, China
| | - Xiaofeng Lu
- Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; (F.M.); (M.X.); (X.H.); (Y.L.); (X.L.)
- Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, Wuhan 430022, China
| | - Xiaoli Wang
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
- Correspondence: (X.W.); (L.C.)
| | - Lili Chen
- Department of Stomatology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; (F.M.); (M.X.); (X.H.); (Y.L.); (X.L.)
- Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, Wuhan 430022, China
- Correspondence: (X.W.); (L.C.)
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17
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Olsen I, Singhrao SK. Low levels of salivary lactoferrin may affect oral dysbiosis and contribute to Alzheimer's disease: A hypothesis. Med Hypotheses 2020; 146:110393. [PMID: 33229194 DOI: 10.1016/j.mehy.2020.110393] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Revised: 10/29/2020] [Accepted: 11/06/2020] [Indexed: 12/13/2022]
Abstract
Recently it has been reported that reduced levels of salivary lactoferrin (LF) can be a plausible biomarker for amyloid beta (Aβ) accumulation in Alzheimer's disease (AD) brains. This could mean that reduced levels of salivary LF act as a trigger for oral dysbiosis and that low LF levels could change the oral microbiota. A chemical change in the composition of saliva has not yet been considered as a cause for microbial dysbiosis but does present an opportunity to view oral dysbiosis as a plausible contributory factor in the development of AD pathophysiology. Oral dysbiosis has largely been reported as a result of inadequate oral hygiene and dry mouth in elderly subjects. Here we discuss if the deficiency of LF in saliva and gingival fluid of AD patients can facilitate proliferation of oral pathogens, and as a result their spread elsewhere in the body. Additionally, we ask if LF in the AD brain could be overexposed as a result of chronic infection. Together these outcomes will indicate if reduced levels of salivary LF can act as a trigger of oral dysbiosis.
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Affiliation(s)
- Ingar Olsen
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway.
| | - 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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