1
|
Zhou X, Kumar P, Bhuyan DJ, Jensen SO, Roberts TL, Münch GW. Neuroinflammation in Alzheimer's Disease: A Potential Role of Nose-Picking in Pathogen Entry via the Olfactory System? Biomolecules 2023; 13:1568. [PMID: 38002250 PMCID: PMC10669446 DOI: 10.3390/biom13111568] [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: 09/13/2023] [Revised: 10/22/2023] [Accepted: 10/23/2023] [Indexed: 11/26/2023] Open
Abstract
Alzheimer's disease (AD) is a complex neurodegenerative disorder characterized by progressive cognitive decline and memory impairment. Many possible factors might contribute to the development of AD, including amyloid peptide and tau deposition, but more recent evidence suggests that neuroinflammation may also play an-at least partial-role in its pathogenesis. In recent years, emerging research has explored the possible involvement of external, invading pathogens in starting or accelerating the neuroinflammatory processes in AD. In this narrative review, we advance the hypothesis that neuroinflammation in AD might be partially caused by viral, bacterial, and fungal pathogens entering the brain through the nose and the olfactory system. The olfactory system represents a plausible route for pathogen entry, given its direct anatomical connection to the brain and its involvement in the early stages of AD. We discuss the potential mechanisms through which pathogens may exploit the olfactory pathway to initiate neuroinflammation, one of them being accidental exposure of the olfactory mucosa to hands contaminated with soil and feces when picking one's nose.
Collapse
Affiliation(s)
- Xian Zhou
- NICM Health Research Institute, Western Sydney University, Westmead, NSW 2145, Australia; (X.Z.); (D.J.B.)
| | - Paayal Kumar
- Pharmacology Unit, School of Medicine, Western Sydney University, Campbelltown, NSW 2560, Australia;
| | - Deep J. Bhuyan
- NICM Health Research Institute, Western Sydney University, Westmead, NSW 2145, Australia; (X.Z.); (D.J.B.)
| | - Slade O. Jensen
- Ingham Institute for Applied Medical Research, Liverpool, NSW 2170, Australia; (S.O.J.); (T.L.R.)
- Microbiology and Infectious Diseases Unit, School of Medicine, Western Sydney University, Liverpool, NSW 2170, Australia
| | - Tara L. Roberts
- Ingham Institute for Applied Medical Research, Liverpool, NSW 2170, Australia; (S.O.J.); (T.L.R.)
- Oncology Unit, School of Medicine, Western Sydney University, Liverpool, NSW 2170, Australia
| | - Gerald W. Münch
- NICM Health Research Institute, Western Sydney University, Westmead, NSW 2145, Australia; (X.Z.); (D.J.B.)
- Pharmacology Unit, School of Medicine, Western Sydney University, Campbelltown, NSW 2560, Australia;
| |
Collapse
|
2
|
Uwishema O, Mahmoud A, Sun J, Correia IFS, Bejjani N, Alwan M, Nicholas A, Oluyemisi A, Dost B. Is Alzheimer's disease an infectious neurological disease? A review of the literature. Brain Behav 2022; 12:e2728. [PMID: 35879909 PMCID: PMC9392514 DOI: 10.1002/brb3.2728] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 07/12/2022] [Indexed: 01/22/2023] Open
Abstract
INTRODUCTION Alzheimer's disease (AD) is a leading cause of dementia around the globe. Its pathogenesis is characterized primarily by the extracellular deposition of amyloid β peptides and intracellular neurofibrillary tangles. Despite the significant investments in neurological research, the exact molecular mechanism of AD pathogenesis is still not fully elucidated. Several studies converge on a hypothesis that pathogenic microbes might play a role in AD progression. Although this hypothesis has been considered relatively weak for decades, it has recently received considerable attention due to increasing evidence on the association between microorganisms and AD. There is a lack of experimental and scientific arguments conveying that these microorganisms engender cognitive and neuropathological deficits and modifications specific to AD, challenging the theory that it could be an infectious neurological disease. This review focuses on recent advances in the infection hypothesis and provides an overview of new findings portraying the significance of pathogenic microbes in AD and the challenges confronting the validity of the hypothesis. METHODOLOGY Data were collected from medical journals published on PubMed, Ovid MEDLINE, ScienceDirect, and Embase bibliographical databases with a predefined search strategy. All articles considering neurological disorders, especially AD associated with infectious diseases, were included. RESULTS This work focused on providing an overview of new findings around the relationship between microorganisms and AD, challenges facing the validity of the theory, and recommendations on how the scientific community can best develop alternative approaches to address the pathophysiology of AD. CONCLUSION While many studies reinforce the suspicion of an infectious etiology of AD, it is important to note that it is yet not validated how microorganisms' presence in the brain can develop AD due to the limited available evidence. Certainly, ground-breaking work is mandatory in this field of research, and these reports so far warrant a thorough investigation into how a chronic infection may remain silent while progressing its neuroinflammation. Amid this uncertainty arises the hope that many researchers will take on this challenge and join this endeavor to benefit AD patients worldwide.
Collapse
Affiliation(s)
- Olivier Uwishema
- Department of Research and Education, Oli Health Magazine Organization, Kigali, Rwanda.,Clinton Global Initiative University, New York, New York, USA.,Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey
| | - Ashraf Mahmoud
- Department of Research and Education, Oli Health Magazine Organization, Kigali, Rwanda.,Faculty of Medicine, Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Jeffrey Sun
- Clinton Global Initiative University, New York, New York, USA.,Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Inês F Silva Correia
- Department of Research and Education, Oli Health Magazine Organization, Kigali, Rwanda.,School of Medicine, Faculty of Health, Medicine, Education and Social Care, Anglia Ruskin University, Chelmsford, UK
| | - Niovi Bejjani
- Department of Research and Education, Oli Health Magazine Organization, Kigali, Rwanda.,Faculty of Medicine, University of Saint Joseph of Beirut, Beirut, Lebanon
| | - Maria Alwan
- Department of Research and Education, Oli Health Magazine Organization, Kigali, Rwanda.,Faculty of Medicine, Beirut Arab University, Beirut, Lebanon
| | - Aderinto Nicholas
- Department of Research and Education, Oli Health Magazine Organization, Kigali, Rwanda.,Department of Medicine and Surgery, Ladoke Akintola University of Technology, Ogbomosho, Nigeria
| | - Adekunbi Oluyemisi
- Department of Research and Education, Oli Health Magazine Organization, Kigali, Rwanda.,School of Public and Allied Health, Babcock University, Ilishan-Remo, Nigeria
| | - Burhan Dost
- Department of Anesthesiology, School of Medicine, Ondokuz Mayis University, Samsun, Turkey
| |
Collapse
|
3
|
Kumar A, Doan VM, Kunkli B, Csősz É. Construction of Unified Human Antimicrobial and Immunomodulatory Peptide Database and Examination of Antimicrobial and Immunomodulatory Peptides in Alzheimer's Disease Using Network Analysis of Proteomics Datasets. Front Genet 2021; 12:633050. [PMID: 33995478 PMCID: PMC8113759 DOI: 10.3389/fgene.2021.633050] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 03/17/2021] [Indexed: 12/26/2022] Open
Abstract
The reanalysis of genomics and proteomics datasets by bioinformatics approaches is an appealing way to examine large amounts of reliable data. This can be especially true in cases such as Alzheimer's disease, where the access to biological samples, along with well-defined patient information can be challenging. Considering the inflammatory part of Alzheimer's disease, our aim was to examine the presence of antimicrobial and immunomodulatory peptides in human proteomic datasets deposited in the publicly available proteomics database ProteomeXchange (http://www.proteomexchange.org/). First, a unified, comprehensive human antimicrobial and immunomodulatory peptide database, containing all known human antimicrobial and immunomodulatory peptides was constructed and used along with the datasets containing high-quality proteomics data originating from the examination of Alzheimer's disease and control groups. A throughout network analysis was carried out, and the enriched GO functions were examined. Less than 1% of all identified proteins in the brain were antimicrobial and immunomodulatory peptides, but the alterations characteristic of Alzheimer's disease could be recapitulated with their analysis. Our data emphasize the key role of the innate immune system and blood clotting in the development of Alzheimer's disease. The central role of antimicrobial and immunomodulatory peptides suggests their utilization as potential targets for mechanistic studies and future therapies.
Collapse
Affiliation(s)
- Ajneesh Kumar
- Proteomics Core Facility, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Biomarker Research Group, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Doctoral School of Molecular Cell and Immune Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Vo Minh Doan
- Proteomics Core Facility, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Biomarker Research Group, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Balázs Kunkli
- Biomarker Research Group, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Doctoral School of Molecular Cell and Immune Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Éva Csősz
- Proteomics Core Facility, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
- Biomarker Research Group, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| |
Collapse
|
4
|
Panza F, Lozupone M, Solfrizzi V, Watling M, Imbimbo BP. Time to test antibacterial therapy in Alzheimer's disease. Brain 2020; 142:2905-2929. [PMID: 31532495 DOI: 10.1093/brain/awz244] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 05/24/2019] [Accepted: 06/14/2019] [Indexed: 12/19/2022] Open
Abstract
Alzheimer's disease is associated with cerebral accumulation of amyloid-β peptide and hyperphosphorylated tau. In the past 28 years, huge efforts have been made in attempting to treat the disease by reducing brain accumulation of amyloid-β in patients with Alzheimer's disease, with no success. While anti-amyloid-β therapies continue to be tested in prodromal patients with Alzheimer's disease and in subjects at risk of developing Alzheimer's disease, there is an urgent need to provide therapeutic support to patients with established Alzheimer's disease for whom current symptomatic treatment (acetylcholinesterase inhibitors and N-methyl d-aspartate antagonist) provide limited help. The possibility of an infectious aetiology for Alzheimer's disease has been repeatedly postulated over the past three decades. Infiltration of the brain by pathogens may act as a trigger or co-factor for Alzheimer's disease, with Herpes simplex virus type 1, Chlamydia pneumoniae, and Porphyromonas gingivalis being most frequently implicated. These pathogens may directly cross a weakened blood-brain barrier, reach the CNS and cause neurological damage by eliciting neuroinflammation. Alternatively, pathogens may cross a weakened intestinal barrier, reach vascular circulation and then cross blood-brain barrier or cause low grade chronic inflammation and subsequent neuroinflammation from the periphery. The gut microbiota comprises a complex community of microorganisms. Increased permeability of the gut and blood-brain barrier induced by microbiota dysbiosis may impact Alzheimer's disease pathogenesis. Inflammatory microorganisms in gut microbiota are associated with peripheral inflammation and brain amyloid-β deposition in subjects with cognitive impairment. Oral microbiota may also influence Alzheimer's disease risk through circulatory or neural access to the brain. At least two possibilities can be envisaged to explain the association of suspected pathogens and Alzheimer's disease. One is that patients with Alzheimer's disease are particularly prone to microbial infections. The other is that microbial infection is a contributing cause of Alzheimer's disease. Therapeutic trials with antivirals and/or antibacterials could resolve this dilemma. Indeed, antiviral agents are being tested in patients with Alzheimer's disease in double-blind placebo-controlled studies. Although combined antibiotic therapy was found to be effective in animal models of Alzheimer's disease, antibacterial drugs are not being widely investigated in patients with Alzheimer's disease. This is because it is not clear which bacterial populations in the gut of patients with Alzheimer's disease are overexpressed and if safe, selective antibacterials are available for them. On the other hand, a bacterial protease inhibitor targeting P. gingivalis toxins is now being tested in patients with Alzheimer's disease. Clinical studies are needed to test if countering bacterial infection may be beneficial in patients with established Alzheimer's disease.
Collapse
Affiliation(s)
- Francesco Panza
- Unit of Epidemiological Research on Aging, National Institute of Gastroenterology 'Saverio de Bellis', Research Hospital, Castellana Grotte, Bari, Italy
| | - Madia Lozupone
- Unit of Epidemiological Research on Aging, National Institute of Gastroenterology 'Saverio de Bellis', Research Hospital, Castellana Grotte, Bari, Italy
- Neurodegenerative Disease Unit, Department of Basic Medicine, Neuroscience, and Sense Organs, University of Bari Aldo Moro, Bari, Italy
| | - Vincenzo Solfrizzi
- 'C. Frugoni' Internal and Geriatric Medicine and Memory Unit, University of Bari Aldo Moro, Bari, Italy
| | - Mark Watling
- Department of Research and Development, Chiesi Farmaceutici, Parma, Italy
| | - Bruno P Imbimbo
- Department of Research and Development, Chiesi Farmaceutici, Parma, Italy
| |
Collapse
|
5
|
Abstract
The symptoms of Alzheimer disease reflect a loss of neural circuit integrity in the brain, but neurons do not work in isolation. Emerging evidence suggests that the intricate balance of interactions between neurons, astrocytes, microglia and vascular cells required for healthy brain function becomes perturbed during the disease, with early changes likely protecting neural circuits from damage, followed later by harmful effects when the balance cannot be restored. Moving beyond a neuronal focus to understand the complex cellular interactions in Alzheimer disease and how these change throughout the course of the disease may provide important insight into developing effective therapeutics.
Collapse
|
6
|
Gosztyla ML, Brothers HM, Robinson SR. Alzheimer's Amyloid-β is an Antimicrobial Peptide: A Review of the Evidence. J Alzheimers Dis 2019; 62:1495-1506. [PMID: 29504537 DOI: 10.3233/jad-171133] [Citation(s) in RCA: 139] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The amyloid-β (Aβ) peptide has long been considered to be the driving force behind Alzheimer's disease (AD). However, clinical trials that have successfully reduced Aβ burden in the brain have not slowed the cognitive decline, and in some instances, have resulted in adverse outcomes. While these results can be interpreted in different ways, a more nuanced picture of Aβ is emerging that takes into account the facts that the peptide is evolutionarily conserved and is present throughout life in cognitively normal individuals. Recent evidence indicates a role for Aβ as an antimicrobial peptide (AMP), a class of innate immune defense molecule that utilizes fibrillation to protect the host from a wide range of infectious agents. In humans and in animal models, infection of the brain frequently leads to increased amyloidogenic processing of the amyloid-β protein precursor (AβPP) and resultant fibrillary aggregates of Aβ. Evidence from in vitro and in vivo studies demonstrates that Aβ oligomers have potent, broad-spectrum antimicrobial properties by forming fibrils that entrap pathogens and disrupt cell membranes. Importantly, overexpression of Aβ confers increased resistance to infection from both bacteria and viruses. The antimicrobial role of Aβ may explain why increased rates of infection have been observed in some of the AD clinical trials that depleted Aβ. Perhaps progress toward a cure for AD will accelerate once treatment strategies begin to take into account the likely physiological functions of this enigmatic peptide.
Collapse
Affiliation(s)
- Maya L Gosztyla
- Department of Neuroscience, The Ohio State University, Columbus, OH, USA
| | - Holly M Brothers
- Department of Psychology, The Ohio State University, Columbus, OH, USA
| | - Stephen R Robinson
- Discipline of Psychology, School of Health and Biomedical Sciences, RMIT University, Bundoora, VIC, Australia
| |
Collapse
|
7
|
Brothers HM, Gosztyla ML, Robinson SR. The Physiological Roles of Amyloid-β Peptide Hint at New Ways to Treat Alzheimer's Disease. Front Aging Neurosci 2018; 10:118. [PMID: 29922148 PMCID: PMC5996906 DOI: 10.3389/fnagi.2018.00118] [Citation(s) in RCA: 210] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Accepted: 04/06/2018] [Indexed: 12/11/2022] Open
Abstract
Amyloid-ß (Aß) is best known as the misfolded peptide that is involved in the pathogenesis of Alzheimer's disease (AD), and it is currently the primary therapeutic target in attempts to arrest the course of this disease. This notoriety has overshadowed evidence that Aß serves several important physiological functions. Aß is present throughout the lifespan, it has been found in all vertebrates examined thus far, and its molecular sequence shows a high degree of conservation. These features are typical of a factor that contributes significantly to biological fitness, and this suggestion has been supported by evidence of functions that are beneficial for the brain. The putative roles of Aß include protecting the body from infections, repairing leaks in the blood-brain barrier, promoting recovery from injury, and regulating synaptic function. Evidence for these beneficial roles comes from in vitro and in vivo studies, which have shown that the cellular production of Aß rapidly increases in response to a physiological challenge and often diminishes upon recovery. These roles are further supported by the adverse outcomes of clinical trials that have attempted to deplete Aß in order to treat AD. We suggest that anti-Aß therapies will produce fewer adverse effects if the known triggers of Aß deposition (e.g., pathogens, hypertension, and diabetes) are addressed first.
Collapse
Affiliation(s)
- Holly M Brothers
- Department of Psychology, The Ohio State University Columbus, Columbus, OH, United States
| | - Maya L Gosztyla
- Department of Neuroscience, The Ohio State University Columbus, Columbus, OH, United States
| | - Stephen R Robinson
- Discipline of Psychology, School of Health and Biomedical Sciences, RMIT University, Melbourne, VIC, Australia
| |
Collapse
|
8
|
Rezvani F, Sayadnasiri M, Rezaei O. The study of memory and executive dysfunction in patients infected with Helicobacter pylori. Neurol Res 2017; 39:953-958. [PMID: 28791919 DOI: 10.1080/01616412.2017.1363349] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Background Infectious agents are considered as potential causes of Alzheimer's disease. Recently, evidence of a high prevalence of Helicobacter pylori (H. pylori) infection in patients with Alzheimer's disease has been observed. The aim of this study was to investigate memory and executive function in H. pylori positive persons not suffering from Alzheimer's or other marked cognitive disorders. Methods This is a cross-sectional study. A total 140 participants were selected using purposive sampling from the patients within the age group of 18-60 years old at Fayyaz Bakhsh Hospital, Tehran in spring 2016. The participants were divided into two groups of H. pylori positive and negative according to results of the serologic tests to measure the levels of specific antibodies of IgA and IgG against H. pylori using ELISA method. They were subsequently assessed using two tests of Trail Making (TMT) part A and B and Wechsler Memory Scale - Third Edition. Data were analyzed using independent t-test and chi-square. The level of significance was considered P-value ≤ 0.05. Results Out of 140 participants, there were 41 male (29.3%) and 99 female (70.7%) among which 84 patients (60%) suffered from H. pylori infection (seropositive) and 56 patients (40%) were not infected. Comparison of the results using independent t-test showed a significant difference (P = 0.006) between the memory scores of patients (M: 106, SD: 8.12) and healthy ones (M: 112, SD: 1.12). In addition, the executive function showed there is a significant difference in the executive ability of seropositive individuals in the two age groups of 20-50 years old (Part A: M: 1.36, SD: 7.11, and Part B: M: 8.8, SD: 8.25 p = 0.01) and over 50 years old (Part A: M: 55, SD: 8.20, and Part B: M: 106, SD: 7.22, p = 0.009). Conclusion The results of this study showed that the infected patients have a lower cognitive performance in comparison to healthy individuals. In other words, H. pylori infection increases the prevalence of memory and executive dysfunction.
Collapse
Affiliation(s)
- Farzaneh Rezvani
- a Department of Clinical Psychology, Science and Research Branch , Islamic Azad University , Tehran , Iran
| | - Mohammad Sayadnasiri
- b Department of Clinical Sciences , University of Social Welfare and Rehabilitation Sciences , Tehran , Iran
| | - Omid Rezaei
- c Psychosis Research Center , University of Social Welfare and Rehabilitation Sciences , Tehran , Iran
| |
Collapse
|
9
|
Bourgade K, Dupuis G, Frost EH, Fülöp T. Anti-Viral Properties of Amyloid-β Peptides. J Alzheimers Dis 2016; 54:859-878. [DOI: 10.3233/jad-160517] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Karine Bourgade
- Research Center on Aging, Graduate Program in Immunology, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Gilles Dupuis
- Department of Biochemistry, Graduate Program in Immunology, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Eric H. Frost
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, Quebec, Canada
| | - Tamàs Fülöp
- Department of Medicine, Research Center on Aging, Graduate Program in Immunology, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, Quebec, Canada
| |
Collapse
|
10
|
Kagan BL, Jang H, Capone R, Arce FT, Ramachandran S, Lal R, Nussinov R. Antimicrobial properties of amyloid peptides. Mol Pharm 2012; 9:708-17. [PMID: 22081976 PMCID: PMC3297685 DOI: 10.1021/mp200419b] [Citation(s) in RCA: 166] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
More than two dozen clinical syndromes known as amyloid diseases are characterized by the buildup of extended insoluble fibrillar deposits in tissues. These amorphous Congo red staining deposits known as amyloids exhibit a characteristic green birefringence and cross-β structure. Substantial evidence implicates oligomeric intermediates of amyloids as toxic species in the pathogenesis of these chronic disease states. A growing body of data has suggested that these toxic species form ion channels in cellular membranes causing disruption of calcium homeostasis, membrane depolarization, energy drainage, and in some cases apoptosis. Amyloid peptide channels exhibit a number of common biological properties including the universal U-shape β-strand-turn-β-strand structure, irreversible and spontaneous insertion into membranes, production of large heterogeneous single-channel conductances, relatively poor ion selectivity, inhibition by Congo red, and channel blockade by zinc. Recent evidence has suggested that increased amounts of amyloids not only are toxic to its host target cells but also possess antimicrobial activity. Furthermore, at least one human antimicrobial peptide, protegrin-1, which kills microbes by a channel-forming mechanism, has been shown to possess the ability to form extended amyloid fibrils very similar to those of classic disease-forming amyloids. In this paper, we will review the reported antimicrobial properties of amyloids and the implications of these discoveries for our understanding of amyloid structure and function.
Collapse
Affiliation(s)
- Bruce L. Kagan
- Department of Psychiatry, David Geffen School of Medicine, Semel Institute for Neuroscience & Human Behavior, University of California, Los Angeles, California 90024, U.S.A
| | - Hyunbum Jang
- Center for Cancer Research Nanobiology Program, SAIC-Frederick, Inc., NCI-Frederick, Frederick, Maryland 21702, U.S.A
| | - Ricardo Capone
- Departments of Bioengineering and of Mechanical and Aerospace Engineering and Material Science Program, University of California, San Diego, La Jolla, California 92093, U.S.A
| | - Fernando Teran Arce
- Departments of Bioengineering and of Mechanical and Aerospace Engineering and Material Science Program, University of California, San Diego, La Jolla, California 92093, U.S.A
| | - Srinivasan Ramachandran
- Departments of Bioengineering and of Mechanical and Aerospace Engineering and Material Science Program, University of California, San Diego, La Jolla, California 92093, U.S.A
| | - Ratnesh Lal
- Departments of Bioengineering and of Mechanical and Aerospace Engineering and Material Science Program, University of California, San Diego, La Jolla, California 92093, U.S.A
| | - Ruth Nussinov
- Center for Cancer Research Nanobiology Program, SAIC-Frederick, Inc., NCI-Frederick, Frederick, Maryland 21702, U.S.A
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| |
Collapse
|
11
|
Chen GH, Wang H, Yang QG, Tao F, Wang C, Xu DX. Acceleration of age-related learning and memory decline in middle-aged CD-1 mice due to maternal exposure to lipopolysaccharide during late pregnancy. Behav Brain Res 2011; 218:267-79. [DOI: 10.1016/j.bbr.2010.11.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2010] [Revised: 08/24/2010] [Accepted: 11/01/2010] [Indexed: 10/18/2022]
|
12
|
Duleu S, Mangas A, Sevin F, Veyret B, Bessede A, Geffard M. Circulating Antibodies to IDO/THO Pathway Metabolites in Alzheimer's Disease. Int J Alzheimers Dis 2010; 2010. [PMID: 20721333 PMCID: PMC2915656 DOI: 10.4061/2010/501541] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Revised: 12/22/2009] [Accepted: 01/20/2010] [Indexed: 01/18/2023] Open
Abstract
In Alzheimer's disease, indoleamine 2,3-dioxygenase and tryptophan hydroxylase are known to induce an overproduction of neurotoxic compounds, such as quinolinic acid and 3-hydroxykynurenine from the former, and 5-hydroxytryptophol and 5-methoxytryptophol from the latter. Other compounds, such as kynurenic acid, serotonin, and melatonin are produced via the same pathways. An improved ELISA method identified circulating antibodies directed against these compounds, linked to proteins, as previously described for other chronic diseases. This describes how only the A isotype of circulating immunoglobulins recognized a pattern of conjugated tryptophan metabolites in the sera of Alzheimer patients. These data indirectly confirmed the involvement of tryptophan derivatives in the pathogenic processes of Alzheimer's disease. Further studies are required to evaluate the relevance of these antibody patterns in monitoring this disease.
Collapse
Affiliation(s)
- S Duleu
- IDRPHT, 33400 Talence, France
| | | | | | | | | | | |
Collapse
|
13
|
Chlamydophila pneumoniae Infection and Its Role in Neurological Disorders. Interdiscip Perspect Infect Dis 2010; 2010:273573. [PMID: 20182626 PMCID: PMC2825657 DOI: 10.1155/2010/273573] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Accepted: 11/25/2009] [Indexed: 12/26/2022] Open
Abstract
Chlamydophila pneumoniae is an intracellular pathogen responsible for a number of different acute and chronic infections. The recent deepening of knowledge on the biology and the use of increasingly more sensitive and
specific molecular techniques has allowed demonstration of C. pneumoniae in
a large number of persons suffering from different diseases including cardiovascular (atherosclerosis and stroke) and central nervous system (CNS) disorders. Despite this, many important issues remain unanswered with regard to the role that C. pneumoniae may play in initiating atheroma or in the progression of the disease. A growing body of evidence concerns the involvement of this pathogen in chronic neurological disorders and particularly in Alzheimer's disease (AD) and Multiple Sclerosis (MS). Monocytes may traffic C. pneumoniae across the blood-brain-barrier, shed the organism in the
CNS and induce neuroinflammation. The demonstration of C. pneumoniae by
histopathological, molecular and culture techniques in the late-onset AD dementia has suggested a relationship between CNS infection with C. pneumoniae and the AD neuropathogenesis. In particular subsets of MS patients, C. pneumoniae could induce a chronic persistent brain infection acting as a cofactor in the development of the disease. The role of Chlamydia in the pathogenesis of mental or neurobehavioral disorders including schizophrenia and autism is uncertain and fragmentary and will require further
confirmation.
Collapse
|
14
|
Holmes C, Cotterell D. Role of infection in the pathogenesis of Alzheimer's disease: implications for treatment. CNS Drugs 2009; 23:993-1002. [PMID: 19958038 DOI: 10.2165/11310910-000000000-00000] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
While our understanding of the neuropathology of Alzheimer's disease continues to grow, its pathogenesis remains a subject of intense debate. Genetic mutations contribute to a minority of early-onset autosomal dominant cases, but most cases are of either late-onset familial or sporadic form. CNS infections, most notably herpes simplex virus type 1, Chlamydophila pneumoniae and several types of spirochetes, have been previously suggested as possible aetiological agents in the development of sporadic Alzheimer's disease but with little consistent evidence. However, peripheral infections may have a role to play in accelerating neurodegeneration in Alzheimer's disease by activating already primed microglial cells within the CNS. Potential pharmacological interventions could aim at modification of this peripheral inflammatory response through targeting various agents involved in this inflammatory pathway. However, benefit could also be gained clinically through the meticulous detection, treatment and prevention of infections in individuals either alone or in combination with anti-inflammatory therapy.
Collapse
Affiliation(s)
- Clive Holmes
- University of Southampton, Memory Assessment and Research Centre, Moorgreen Hospital, Southampton, UK.
| | | |
Collapse
|
15
|
van Groen T, Kadish I, Popović N, Popović M, Caballero-Bleda M, Baño-Otálora B, Vivanco P, Rol MÁ, Madrid JA. Age-related brain pathology in Octodon degu: blood vessel, white matter and Alzheimer-like pathology. Neurobiol Aging 2009; 32:1651-61. [PMID: 19910078 DOI: 10.1016/j.neurobiolaging.2009.10.008] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Revised: 09/29/2009] [Accepted: 10/14/2009] [Indexed: 01/09/2023]
Abstract
Recently it has been shown that over 3-year-old wild-type South American rodents, Octodon degus, the "common degu" or degu, of their own accord develop Alzheimer's disease neuropathological hallmarks: amyloid-β-peptide depositions and accumulation of tau-protein. Here we analyzed brains of 1-, 3- and 6-year-old degu's, bred in standard animal facilities. Significant amounts of Aβ and tau deposits are present in the hippocampal formation of 6-year-old O. degus, primarily in the white matter, but these hippocampal Aβ and tau deposits are not present in younger ones. In contrast, significant Aβ deposits in blood vessel walls are already found in 3-year-old animals. The tau deposits in the hippocampal formation coincide with a significant decrease in staining for myelin in the same areas, indicating hippocampal disconnection and, likely, dysfunction. Our findings indicate that (1) cerebral amyloid angiopathy precedes brain parenchyma pathology in aged degu's and (2) the onset of disease seems to be delayed in the laboratory vs. wild-type degu's.
Collapse
Affiliation(s)
- Thomas van Groen
- Department of Cell Biology, Center for Glial Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Kountouras J, Boziki M, Gavalas E, Zavos C, Deretzi G, Grigoriadis N, Tsolaki M, Chatzopoulos D, Katsinelos P, Tzilves D, Zabouri A, Michailidou I. Increased Cerebrospinal Fluid Helicobacter Pylori Antibody in Alzheimer’s Disease. Int J Neurosci 2009; 119:765-77. [DOI: 10.1080/00207450902782083] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
|
17
|
Eradication of Helicobacter pylori may be beneficial in the management of Alzheimer’s disease. J Neurol 2009; 256:758-67. [DOI: 10.1007/s00415-009-5011-z] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Revised: 11/26/2008] [Accepted: 12/10/2008] [Indexed: 12/13/2022]
|
18
|
Watts A, Crimmins EM, Gatz M. Inflammation as a potential mediator for the association between periodontal disease and Alzheimer's disease. Neuropsychiatr Dis Treat 2008; 4:865-76. [PMID: 19183779 PMCID: PMC2626915 DOI: 10.2147/ndt.s3610] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Periodontal disease (PDD) is associated with increased risk of cardiovascular disease, cerebrovascular disease, and mortality in many studies, while other studies have begun to suggest an association of PDD with Alzheimer's disease (AD). This paper discusses how infectious pathogens and systemic infection may play a role in AD. The roles of infection and inflammation are addressed specifically with regard to known AD pathologic lesions including senile plaques, neuron death, neurofibrillary tangles, and cerebrovascular changes. A testable model of proposed pathways between periodontal infection and AD is presented including three possible mechanisms: a) direct effects of infectious pathogens, b) inflammatory response to pathogens, and c) the effects on vascular integrity. The role of gene polymorphisms is discussed, including apolipoprotein (APOE) varepsilon4 as a pro-inflammatory and pro-infection genotype.
Collapse
Affiliation(s)
- Amber Watts
- Davis School of Gerontology, University of Southern California, Los Angeles, CA, USA.
| | | | | |
Collapse
|
19
|
Stallings TL. Association of Alzheimer's disease and Chlamydophila pneumoniae. J Infect 2008; 56:423-31. [PMID: 18474399 DOI: 10.1016/j.jinf.2008.03.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Revised: 03/26/2008] [Accepted: 03/31/2008] [Indexed: 10/22/2022]
Abstract
This paper critically reviews the association of infection by Chlamydophila pneumoniae (C. pneumoniae) and Alzheimer's disease (AD). The aging population has increased interest in finding the cause of AD, but studies have yielded contradictory results that are likely due to varying diagnostic tools and different uses of diagnostic tests. Knowledge of AD's characteristics, risk factors, and hypothesized etiologies has expanded since Alois Alzheimer's initial description of AD. Epidemiologic and projection studies provide incidence estimates of AD through a two-stage method: (1) primary diagnosis of dementia by cognitive testing such as Mini-Mental State Examination (MMSE), and (2) clinical diagnosis of AD through criteria such as National Institute of Neurological and Communicative Diseases and Stroke/Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA). Cross-sectional studies yield prevalence estimates of infection by C. pneumoniae by detecting immunoglobulins through laboratory tests such as microimmunofluorescence (MIF). Studies examining the association of C. pneumoniae and AD are limited, but brain autopsy provides information about presence, proximity to areas associated with AD, and bacterial load. Standardization of diagnostic techniques would allow for better comparability of studies, but uncertainty about the best method of diagnosis of infection by C. pneumoniae and AD may call for revised or novel diagnostic tools.
Collapse
Affiliation(s)
- Tiffany L Stallings
- Rollins School of Public Health, Department of Epidemiology, Emory University, 1518 Clifton Road NE, 4th Floor, Atlanta, GA 30322, USA.
| |
Collapse
|
20
|
Kountouras J, Gavalas E, Zavos C, Stergiopoulos C, Chatzopoulos D, Kapetanakis N, Gisakis D. Alzheimer's disease and Helicobacter pylori infection: Defective immune regulation and apoptosis as proposed common links. Med Hypotheses 2006; 68:378-88. [PMID: 16979298 DOI: 10.1016/j.mehy.2006.06.052] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Accepted: 06/21/2006] [Indexed: 11/20/2022]
Abstract
Although degenerative diseases of the central nervous system, including Alzheimer's disease (AD), have an increasingly high impact on aged population their association with Helicobacter pylori (H. pylori) infection has not as yet been thoroughly researched. Current H. pylori infection appears to induce irregular humoral and cellular immune responses that, owing to the sharing of homologous epitopes (molecular mimicry), cross-react with components of nerves, thereby contributing and possibly perpetuating the apoptotic neural tissue damage observed in neurodegenerative diseases including AD. An association between AD and H. pylori infection has been recently addressed by two studies. A higher seropositivity for anti-H. pylori immunoglobulin G antibodies in 30 patients with AD than in 30 age-matched controls was reported in one study; this serological test, however, has limitations because it does not discriminate between current and old infections. In the other study, by introducing the histological method (the actual gold standard) for diagnosis of H. pylori infection, we reported a higher prevalence of H. pylori infection in 50 AD patients than in 30 anemic controls. This pathogen may influence the pathophysiology of AD by promoting platelet and platelet-leukocyte aggregation; releasing various pro-inflammatory and vasoactive substances; developing cross-mimicry with host antigens; producing reactive oxygen metabolites and circulating lipid peroxides; influencing the apoptotic process; and increasing, through induction of atrophic gastritis, homocysteine, which contributes to vascular disorders implicated in endothelial damage and neurodegeneration.
Collapse
Affiliation(s)
- Jannis Kountouras
- Department of Medicine, Second Medical Clinic, Aristotle University of Thessaloniki, Ippokration Hospital, Thessaloniki, Greece.
| | | | | | | | | | | | | |
Collapse
|
21
|
Rahman MA, Azuma Y, Fukunaga H, Murakami T, Sugi K, Fukushi H, Miura K, Suzuki H, Shirai M. Serotonin and melatonin, neurohormones for homeostasis, as novel inhibitors of infections by the intracellular parasite chlamydia. J Antimicrob Chemother 2005; 56:861-8. [PMID: 16172105 DOI: 10.1093/jac/dki331] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES Chlamydiae are obligate intracellular bacteria, causing a variety of diseases, i.e. pneumonia, sexually transmitted disease, conjunctivitis and zoonosis. Tryptophan depletion by interferon-gamma (IFN-gamma) is the most important host defence system against chlamydial infection. Thus chlamydial tryptophan metabolism is thought to play key roles for IFN-gamma resistance, persistent infection and host/tissue tropisms. We tested tryptophan derivatives for activity against chlamydia-infected cells. METHODS Rates of chlamydial infection and sizes of the inclusions were evaluated by in vitro infection using three Chlamydiaceae species, Chlamydia trachomatis, Chlamydophila pneumoniae and Chlamydophila felis, which show significant divergence of tryptophan synthesis genes and different susceptibilities to IFN-gamma. RESULTS Melatonin and serotonin, which are recognized as neural hormones for maintenance of organism homeostasis, reduced chlamydial infection but not other bacterial growth tested here. Unlike IFN-gamma, melatonin limited infection of all three chlamydiae and the effects were not recovered by tryptophan supplementation. Melatonin treatment only of host cells could diminish infection and the infection reduction was neutralized by a pertussis toxin, an inhibitor of G proteins. Ligands of melatonin and serotonin receptors also hampered infection. CONCLUSIONS Inhibition mechanisms of chlamydial infection by melatonin and serotonin appear to be different from those of IFN-gamma and involve specific G-protein-coupled receptors. Melatonin is deemed to inhibit early progression of the chlamydial development cycle, such as establishment of intracellular infection and/or conversion from elementary body to reticulate body. Utilization of melatonin, serotonin or their derivatives may be advantageous for harmless prevention of chlamydial infection.
Collapse
Affiliation(s)
- Mohd Akhlakur Rahman
- Department of Microbiology, Yamaguchi University School of Medicine, 1-1-1, Minamikogushi, Ube, Yamaguchi 755-8505, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Combarros O, Infante J, Rodríguez E, Llorca J, Peña N, Fernández-Viadero C, Berciano J. CD14 receptor polymorphism and Alzheimer's disease risk. Neurosci Lett 2005; 380:193-6. [PMID: 15854776 DOI: 10.1016/j.neulet.2005.01.082] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2004] [Revised: 01/12/2005] [Accepted: 01/13/2005] [Indexed: 11/18/2022]
Abstract
Activation of microglial cells is involved in the inflammatory component of Alzheimer's disease (AD), and it may be triggered by infectious pathogens. CD14, a receptor upregulated in activated microglia, plays a central role in innate immunity through recognition of bacterial lipopolysaccharide and initiation of inflammatory response. A polymorphism in the promoter region (-260) of the CD14 receptor has been found to be related to increased risk of bacterial infections and inflammatory diseases such as atherosclerosis. In a case-control study utilizing a clinically well-defined group of 310 sporadic AD patients and 310 control subjects, we investigated whether the CD14 (-260) polymorphism might be responsible for susceptibility to AD, and we also examined the combined gene effects between CD14 and APOE and several other proinflammatory cytokine genes. The current study does not demonstrate an association between CD14 (-260) polymorphism and AD, neither through an independent effect nor through interaction with APOE epsilon4 allele or interleukin (IL)-1A, IL-6, IL-8, tumor necrosis factor (TNF)-alpha, and intercellular adhesion molecule-1 polymorphisms.
Collapse
Affiliation(s)
- Onofre Combarros
- Service of Neurology, University Hospital Marqués de Valdecilla, University of Cantabria, 39008 Santander, Spain.
| | | | | | | | | | | | | |
Collapse
|
23
|
Kinoshita J. Pathogens as a cause of Alzheimer’s disease. Neurobiol Aging 2004; 25:639-40. [PMID: 15172742 DOI: 10.1016/j.neurobiolaging.2004.02.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2003] [Accepted: 02/17/2004] [Indexed: 11/16/2022]
|