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Subedi L, Gaire BP, Koronyo Y, Koronyo-Hamaoui M, Crother TR. Chlamydia pneumoniae in Alzheimer's disease pathology. Front Neurosci 2024; 18:1393293. [PMID: 38770241 PMCID: PMC11102982 DOI: 10.3389/fnins.2024.1393293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 04/22/2024] [Indexed: 05/22/2024] Open
Abstract
While recent advances in diagnostics and therapeutics offer promising new approaches for Alzheimer's disease (AD) diagnosis and treatment, there is still an unmet need for an effective remedy, suggesting new avenues of research are required. Besides many plausible etiologies for AD pathogenesis, mounting evidence supports a possible role for microbial infections. Various microbes have been identified in the postmortem brain tissues of human AD patients. Among bacterial pathogens in AD, Chlamydia pneumoniae (Cp) has been well characterized in human AD brains and is a leading candidate for an infectious involvement. However, no definitive studies have been performed proving or disproving Cp's role as a causative or accelerating agent in AD pathology and cognitive decline. In this review, we discuss recent updates for the role of Cp in human AD brains as well as experimental models of AD. Furthermore, based on the current literature, we have compiled a list of potential mechanistic pathways which may connect Cp with AD pathology.
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Affiliation(s)
- Lalita Subedi
- Department of Pediatrics, Division of Infectious Diseases and Immunology, Guerin Children's at Cedars-Sinai Medical Center, Los Angeles, CA, United States
- Infectious and Immunologic Diseases Research Center (IIDRC), Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Bhakta Prasad Gaire
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Yosef Koronyo
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Maya Koronyo-Hamaoui
- Department of Neurosurgery, Maxine Dunitz Neurosurgical Research Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, United States
- Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Timothy R. Crother
- Department of Pediatrics, Division of Infectious Diseases and Immunology, Guerin Children's at Cedars-Sinai Medical Center, Los Angeles, CA, United States
- Infectious and Immunologic Diseases Research Center (IIDRC), Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, United States
- Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA, United States
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2
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Jaramillo-Rangel G, Chávez-Briones MDL, Ancer-Arellano A, Miranda-Maldonado I, Ortega-Martínez M. Back to the Basics: Usefulness of Naturally Aged Mouse Models and Immunohistochemical and Quantitative Morphologic Methods in Studying Mechanisms of Lung Aging and Associated Diseases. Biomedicines 2023; 11:2075. [PMID: 37509714 PMCID: PMC10377355 DOI: 10.3390/biomedicines11072075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2023] [Revised: 06/17/2023] [Accepted: 07/19/2023] [Indexed: 07/30/2023] Open
Abstract
Aging-related molecular and cellular alterations in the lung contribute to an increased susceptibility of the elderly to devastating diseases. Although the study of the aging process in the lung may benefit from the use of genetically modified mouse models and omics techniques, these approaches are still not available to most researchers and produce complex results. In this article, we review works that used naturally aged mouse models, together with immunohistochemistry (IHC) and quantitative morphologic (QM) methods in the study of the mechanisms of the aging process in the lung and its most commonly associated disorders: cancer, chronic obstructive pulmonary disease (COPD), and infectious diseases. The advantage of using naturally aged mice is that they present characteristics similar to those observed in human aging. The advantage of using IHC and QM methods lies in their simplicity, economic accessibility, and easy interpretation, in addition to the fact that they provide extremely important information. The study of the aging process in the lung and its associated diseases could allow the design of appropriate therapeutic strategies, which is extremely important considering that life expectancy and the number of elderly people continue to increase considerably worldwide.
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Affiliation(s)
- Gilberto Jaramillo-Rangel
- Department of Pathology, School of Medicine, Autonomous University of Nuevo León, Monterrey 64460, Mexico
| | | | - Adriana Ancer-Arellano
- Department of Pathology, School of Medicine, Autonomous University of Nuevo León, Monterrey 64460, Mexico
| | - Ivett Miranda-Maldonado
- Department of Pathology, School of Medicine, Autonomous University of Nuevo León, Monterrey 64460, Mexico
| | - Marta Ortega-Martínez
- Department of Pathology, School of Medicine, Autonomous University of Nuevo León, Monterrey 64460, Mexico
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3
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Abbate C. The Adult Neurogenesis Theory of Alzheimer's Disease. J Alzheimers Dis 2023:JAD221279. [PMID: 37182879 DOI: 10.3233/jad-221279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Alzheimer's disease starts in neural stem cells (NSCs) in the niches of adult neurogenesis. All primary factors responsible for pathological tau hyperphosphorylation are inherent to adult neurogenesis and migration. However, when amyloid pathology is present, it strongly amplifies tau pathogenesis. Indeed, the progressive accumulation of extracellular amyloid-β deposits in the brain triggers a state of chronic inflammation by microglia. Microglial activation has a significant pro-neurogenic effect that fosters the process of adult neurogenesis and supports neuronal migration. Unfortunately, this "reactive" pro-neurogenic activity ultimately perturbs homeostatic equilibrium in the niches of adult neurogenesis by amplifying tau pathogenesis in AD. This scenario involves NSCs in the subgranular zone of the hippocampal dentate gyrus in late-onset AD (LOAD) and NSCs in the ventricular-subventricular zone along the lateral ventricles in early-onset AD (EOAD), including familial AD (FAD). Neuroblasts carrying the initial seed of tau pathology travel throughout the brain via neuronal migration driven by complex signals and convey the disease from the niches of adult neurogenesis to near (LOAD) or distant (EOAD) brain regions. In these locations, or in close proximity, a focus of degeneration begins to develop. Then, tau pathology spreads from the initial foci to large neuronal networks along neural connections through neuron-to-neuron transmission.
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Affiliation(s)
- Carlo Abbate
- IRCCS Fondazione Don Carlo Gnocchi ONLUS, Milan, Italy
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Vojtechova I, Machacek T, Kristofikova Z, Stuchlik A, Petrasek T. Infectious origin of Alzheimer’s disease: Amyloid beta as a component of brain antimicrobial immunity. PLoS Pathog 2022; 18:e1010929. [PMCID: PMC9671327 DOI: 10.1371/journal.ppat.1010929] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The amyloid cascade hypothesis, focusing on pathological proteins aggregation, has so far failed to uncover the root cause of Alzheimer’s disease (AD), or to provide an effective therapy. This traditional paradigm essentially explains a mechanism involved in the development of sporadic AD rather than its cause. The failure of an overwhelming majority of clinical studies (99.6%) demonstrates that a breakthrough in therapy would be difficult if not impossible without understanding the etiology of AD. It becomes more and more apparent that the AD pathology might originate from brain infection. In this review, we discuss a potential role of bacteria, viruses, fungi, and eukaryotic parasites as triggers of AD pathology. We show evidence from the current literature that amyloid beta, traditionally viewed as pathological, actually acts as an antimicrobial peptide, protecting the brain against pathogens. However, in case of a prolonged or excessive activation of a senescent immune system, amyloid beta accumulation and aggregation becomes damaging and supports runaway neurodegenerative processes in AD. This is paralleled by the recent study by Alam and colleagues (2022) who showed that alpha-synuclein, the protein accumulating in synucleinopathies, also plays a critical physiological role in immune reactions and inflammation, showing an unforeseen link between the 2 unrelated classes of neurodegenerative disorders. The multiplication of the amyloid precursor protein gene, recently described by Lee and collegues (2018), and possible reactivation of human endogenous retroviruses by pathogens fits well into the same picture. We discuss these new findings from the viewpoint of the infection hypothesis of AD and offer suggestions for future research. More than a century after its discovery, Alzheimer’s disease (AD) remains incurable and mysterious. The dominant hypothesis of amyloid cascade has succeeded in explaining the key pathological mechanism, but not its trigger. Amyloid beta has been traditionally considered a pathological peptide, and its physiological functions remain poorly known. These knowledge gaps have contributed to repeated failures of clinical studies. The emerging infectious hypothesis of AD considers central nervous system (CNS) infection the primary trigger of sporadic AD. A closely connected hypothesis claims that amyloid beta is an antimicrobial peptide. In this review, we discuss the available evidence for the involvement of infections in AD, coming from epidemiological studies, post mortem analyses of brain tissue, and experiments in vitro and in vivo. We argue there is no unique “Alzheimer’s germ,” instead, AD is a general reaction of the CNS to chronic infections, in the milieu of an aged immune system. The pathology may become self-sustained even without continuous presence of microbes in the brain. Importantly, the infectious hypothesis leads to testable predictions. Targeting amyloid beta should be ineffective, unless the triggering pathogen and inflammatory response are addressed as well. Meticulous control of selected infections might be the best near-term strategy for AD prevention.
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Affiliation(s)
- Iveta Vojtechova
- National Institute of Mental Health, Klecany, Czech Republic
- Laboratory of Neurophysiology of Memory, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
- * E-mail: , (IV); , (TP)
| | - Tomas Machacek
- Department of Parasitology, Faculty of Science, Charles University, Prague, Czech Republic
| | | | - Ales Stuchlik
- National Institute of Mental Health, Klecany, Czech Republic
- Laboratory of Neurophysiology of Memory, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Tomas Petrasek
- National Institute of Mental Health, Klecany, Czech Republic
- Laboratory of Neurophysiology of Memory, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
- * E-mail: , (IV); , (TP)
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Xie J, Tian S, Liu J, Cao R, Yue P, Cai X, Shang Q, Yang M, Han L, Zhang DK. Dual role of the nasal microbiota in neurological diseases—An unignorable risk factor or a potential therapy carrier. Pharmacol Res 2022; 179:106189. [DOI: 10.1016/j.phrs.2022.106189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 03/06/2022] [Accepted: 03/17/2022] [Indexed: 12/11/2022]
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Chlamydia pneumoniae can infect the central nervous system via the olfactory and trigeminal nerves and contributes to Alzheimer's disease risk. Sci Rep 2022; 12:2759. [PMID: 35177758 PMCID: PMC8854390 DOI: 10.1038/s41598-022-06749-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 02/07/2022] [Indexed: 02/07/2023] Open
Abstract
Chlamydia pneumoniae is a respiratory tract pathogen but can also infect the central nervous system (CNS). Recently, the link between C. pneumoniae CNS infection and late-onset dementia has become increasingly evident. In mice, CNS infection has been shown to occur weeks to months after intranasal inoculation. By isolating live C. pneumoniae from tissues and using immunohistochemistry, we show that C. pneumoniae can infect the olfactory and trigeminal nerves, olfactory bulb and brain within 72 h in mice. C. pneumoniae infection also resulted in dysregulation of key pathways involved in Alzheimer’s disease pathogenesis at 7 and 28 days after inoculation. Interestingly, amyloid beta accumulations were also detected adjacent to the C. pneumoniae inclusions in the olfactory system. Furthermore, injury to the nasal epithelium resulted in increased peripheral nerve and olfactory bulb infection, but did not alter general CNS infection. In vitro, C. pneumoniae was able to infect peripheral nerve and CNS glia. In summary, the nerves extending between the nasal cavity and the brain constitute invasion paths by which C. pneumoniae can rapidly invade the CNS likely by surviving in glia and leading to Aβ deposition.
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7
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Ni J, Wu Z. Inflammation Spreading: Negative Spiral Linking Systemic Inflammatory Disorders and Alzheimer's Disease. Front Cell Neurosci 2021; 15:638686. [PMID: 33716675 PMCID: PMC7947253 DOI: 10.3389/fncel.2021.638686] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 02/03/2021] [Indexed: 12/15/2022] Open
Abstract
As a physiological response to injury in the internal body organs, inflammation is responsible for removing dangerous stimuli and initiating healing. However, persistent and exaggerative chronic inflammation causes undesirable negative effects in the organs. Inflammation occurring in the brain and spinal cord is known as neuroinflammation, with microglia acting as the central cellular player. There is increasing evidence suggesting that chronic neuroinflammation is the most relevant pathological feature of Alzheimer’s disease (AD), regulating other pathological features, such as the accumulation of amyloid-β (Aβ) and hyperphosphorylation of Tau. Systemic inflammatory signals caused by systemic disorders are known to strongly influence neuroinflammation as a consequence of microglial activation, inflammatory mediator production, and the recruitment of peripheral immune cells to the brain, resulting in neuronal dysfunction. However, the neuroinflammation-accelerated neuronal dysfunction in AD also influences the functions of peripheral organs. In the present review, we highlight the link between systemic inflammatory disorders and AD, with inflammation serving as the common explosion. We discuss the molecular mechanisms that govern the crosstalk between systemic inflammation and neuroinflammation. In our view, inflammation spreading indicates a negative spiral between systemic diseases and AD. Therefore, “dampening inflammation” through the inhibition of cathepsin (Cat)B or CatS may be a novel therapeutic approach for delaying the onset of and enacting early intervention for AD.
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Affiliation(s)
- Junjun Ni
- Key Laboratory of Molecular Medicine and Biotherapy, Department of Biology, School of Life Science, Beijing Institute of Technology, Beijing, China
| | - Zhou Wu
- Department of Aging Science and Pharmacology, Faculty of Dental Science, Kyushu University, Fukuoka, Japan.,OBT Research Center, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
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8
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Nazareth L, Walkden H, Chacko A, Delbaz A, Shelper T, Armitage CW, Reshamwala R, Trim LK, St John JA, Beagley KW, Ekberg JAK. Chlamydia muridarum Can Invade the Central Nervous System via the Olfactory and Trigeminal Nerves and Infect Peripheral Nerve Glial Cells. Front Cell Infect Microbiol 2021; 10:607779. [PMID: 33489937 PMCID: PMC7819965 DOI: 10.3389/fcimb.2020.607779] [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] [Received: 09/18/2020] [Accepted: 11/23/2020] [Indexed: 12/11/2022] Open
Abstract
Chlamydia pneumoniae can infect the brain and has been linked to late-onset dementia. Chlamydia muridarum, which infects mice, is often used to model human chlamydial infections. While it has been suggested to be also important for modelling brain infection, nervous system infection by C. muridarum has not been reported in the literature. C. pneumoniae has been shown to infect the olfactory bulb in mice after intranasal inoculation, and has therefore been suggested to invade the brain via the olfactory nerve; however, nerve infection has not been shown to date. Another path by which certain bacteria can reach the brain is via the trigeminal nerve, but it remains unknown whether Chlamydia species can infect this nerve. Other bacteria that can invade the brain via the olfactory and/or trigeminal nerve can do so rapidly, however, whether Chlamydia spp. can reach the brain earlier than one-week post inoculation remains unknown. In the current study, we showed that C. muridarum can within 48 h invade the brain via the olfactory nerve, in addition to infecting the trigeminal nerve. We also cultured the glial cells of the olfactory and trigeminal nerves and showed that C. muridarum readily infected the cells, constituting a possible cellular mechanism explaining how the bacteria can invade the nerves without being eliminated by glial immune functions. Further, we demonstrated that olfactory and trigeminal glia differed in their responses to C. muridarum, with olfactory glia showing less infection and stronger immune response than trigeminal glia.
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Affiliation(s)
- Lynn Nazareth
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia
| | - Heidi Walkden
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia
| | - Anu Chacko
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia
| | - Ali Delbaz
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia
| | - Todd Shelper
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia
| | - Charles W Armitage
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Ronak Reshamwala
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia
| | - Logan K Trim
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - James A St John
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia.,Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
| | - Kenneth W Beagley
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Jenny A K Ekberg
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia.,Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia.,Griffith Institute for Drug Discovery, Griffith University, Nathan, QLD, Australia
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9
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Balin BJ, Hudson AP. Perspectives on the Intracellular Bacterium Chlamydia pneumoniae in Late-Onset Dementia. CURRENT CLINICAL MICROBIOLOGY REPORTS 2020. [DOI: 10.1007/s40588-020-00146-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Abstract
Purpose of Review
Chronic diseases remain a daunting challenge for clinicians and researchers alike. While difficult to completely understand, most chronic diseases, including late-onset dementias, are thought to arise as an interplay between host genetic factors and environmental insults. One of the most diverse and ubiquitous environmental insults centers on infectious agents. Associations of infectious agents with late-onset dementia have taken on heightened importance, including our investigations of infection by the intracellular respiratory bacterium, Chlamydia pneumoniae (Cpn), in late-onset dementia of the Alzheimer’s type.
Recent Findings
Over the last two decades, the relationship of this infection to pathogenesis in late-onset dementia has become much clearer. This clarity has resulted from applying contemporary molecular genetic, biochemical, immunochemical, and cell culture techniques to analysis of human brains, animal models, and relevant in vitro cell culture systems. Data from these studies, taken in aggregate form, now can be applied to evaluation of proof of concept for causation of this infection with late-onset disease. In this evaluation, modifications to the original Koch postulates can be useful for elucidating causation.
Summary
All such relevant studies are outlined and summarized in this review, and they demonstrate the utility of applying modified Koch postulates to the etiology of late-onset dementia of the Alzheimer’s type. Regardless, it is clear that even with strong observational evidence, in combination with application of modifications of Koch’s postulates, we will not be able to conclusively state that Cpn infection is causative for disease pathogenesis in late-onset dementia. Moreover, this conclusion obtains as well for the putative causation of this condition by other pathogens, including herpes simplex virus type 1, Borrelia burgdorferi, and Porphyromonas gingivalis.
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Woods JJ, Skelding KA, Martin KL, Aryal R, Sontag E, Johnstone DM, Horvat JC, Hansbro PM, Milward EA. Assessment of evidence for or against contributions of Chlamydia pneumoniae infections to Alzheimer's disease etiology. Brain Behav Immun 2020; 83:22-32. [PMID: 31626972 DOI: 10.1016/j.bbi.2019.10.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Revised: 09/26/2019] [Accepted: 10/14/2019] [Indexed: 02/07/2023] Open
Abstract
Alzheimer's disease, the most common form of dementia, was first formally described in 1907 yet its etiology has remained elusive. Recent proposals that Aβ peptide may be part of the brain immune response have revived longstanding contention about the possibility of causal relationships between brain pathogens and Alzheimer's disease. Research has focused on infectious pathogens that may colonize the brain such as herpes simplex type I. Some researchers have proposed the respiratory bacteria Chlamydia pneumoniae may also be implicated in Alzheimer's disease, however this remains controversial. This review aims to provide a balanced overview of the current evidence and its limitations and future approaches that may resolve controversies. We discuss the evidence from in vitro, animal and human studies proposed to implicate Chlamydia pneumoniae in Alzheimer's disease and other neurological conditions, the potential mechanisms by which the bacterium may contribute to pathogenesis and limitations of previous studies that may explain the inconsistencies in the literature.
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Affiliation(s)
- Jason J Woods
- School of Biomedical Sciences and Pharmacy, University Drive, University of Newcastle, Callaghan NSW 2308, Australia.
| | - Kathryn A Skelding
- School of Biomedical Sciences and Pharmacy, University Drive, University of Newcastle, Callaghan NSW 2308, Australia
| | - Kristy L Martin
- School of Biomedical Sciences and Pharmacy, University Drive, University of Newcastle, Callaghan NSW 2308, Australia; Discipline of Physiology and Bosch Institute, Anderson Stuart Building F13, University of Sydney, NSW 2006, Australia
| | - Ritambhara Aryal
- School of Biomedical Sciences and Pharmacy, University Drive, University of Newcastle, Callaghan NSW 2308, Australia
| | - Estelle Sontag
- School of Biomedical Sciences and Pharmacy, University Drive, University of Newcastle, Callaghan NSW 2308, Australia
| | - Daniel M Johnstone
- Discipline of Physiology and Bosch Institute, Anderson Stuart Building F13, University of Sydney, NSW 2006, Australia
| | - Jay C Horvat
- Hunter Medical Research Institute, Lot 1 Kookaburra Circuit, New Lambton Heights NSW 2305, Australia
| | - Philip M Hansbro
- School of Biomedical Sciences and Pharmacy, University Drive, University of Newcastle, Callaghan NSW 2308, Australia; Hunter Medical Research Institute, Lot 1 Kookaburra Circuit, New Lambton Heights NSW 2305, Australia; Centre for Inflammation, Centenary Institute, Camperdown NSW 2050, Australia; Centre for Inflammation, Faculty of Science, University of Technology Sydney, Ultimo NSW 2007, Australia
| | - Elizabeth A Milward
- School of Biomedical Sciences and Pharmacy, University Drive, University of Newcastle, Callaghan NSW 2308, Australia
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Balin BJ, Hammond CJ, Little CS, Hingley ST, Al-Atrache Z, Appelt DM, Whittum-Hudson JA, Hudson AP. Chlamydia pneumoniae: An Etiologic Agent for Late-Onset Dementia. Front Aging Neurosci 2018; 10:302. [PMID: 30356749 PMCID: PMC6189393 DOI: 10.3389/fnagi.2018.00302] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 09/13/2018] [Indexed: 01/02/2023] Open
Abstract
The disease known as late-onset Alzheimer's disease is a neurodegenerative condition recognized as the single most commonform of senile dementia. The condition is sporadic and has been attributed to neuronal damage and loss, both of which have been linked to the accumulation of protein deposits in the brain. Significant progress has been made over the past two decades regarding our overall understanding of the apparently pathogenic entities that arise in the affected brain, both for early-onset disease, which constitutes approximately 5% of all cases, as well as late-onset disease, which constitutes the remainder of cases. Observable neuropathology includes: neurofibrillary tangles, neuropil threads, neuritic senile plaques and often deposits of amyloid around the cerebrovasculature. Although many studies have provided a relatively detailed knowledge of these putatively pathogenic entities, understanding of the events that initiate and support the biological processes generating them and the subsequent observable neuropathology and neurodegeneration remain limited. This is especially true in the case of late-onset disease. Although early-onset Alzheimer's disease has been shown conclusively to have genetic roots, the detailed etiologic initiation of late-onset disease without such genetic origins has remained elusive. Over the last 15 years, current and ongoing work has implicated infection in the etiology and pathogenesis of late-onset dementia. Infectious agents reported to be associated with disease initiation are various, including several viruses and pathogenic bacterial species. We have reported extensively regarding an association between late-onset disease and infection with the intracellular bacterial pathogen Chlamydia pneumoniae. In this article, we review previously published data and recent results that support involvement of this unusual respiratory pathogen in disease induction and development. We further suggest several areas for future research that should elucidate details relating to those processes, and we argue for a change in the designation of the disease based on increased understanding of its clinical attributes.
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Affiliation(s)
- Brian J Balin
- Department of Bio-Medical Sciences, Center for Chronic Disorders of Aging, Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
| | - Christine J Hammond
- Department of Bio-Medical Sciences, Center for Chronic Disorders of Aging, Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
| | - Christopher Scott Little
- Department of Bio-Medical Sciences, Center for Chronic Disorders of Aging, Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
| | - Susan T Hingley
- Department of Bio-Medical Sciences, Center for Chronic Disorders of Aging, Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
| | - Zein Al-Atrache
- Department of Bio-Medical Sciences, Center for Chronic Disorders of Aging, Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
| | - Denah M Appelt
- Department of Bio-Medical Sciences, Center for Chronic Disorders of Aging, Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
| | - Judith A Whittum-Hudson
- Department of Biochemistry, Immunology and Microbiology, Wayne State University School of Medicine, Detroit, MI, United States
| | - Alan P Hudson
- Department of Biochemistry, Immunology and Microbiology, Wayne State University School of Medicine, Detroit, MI, United States
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Fülöp T, Itzhaki RF, Balin BJ, Miklossy J, Barron AE. Role of Microbes in the Development of Alzheimer's Disease: State of the Art - An International Symposium Presented at the 2017 IAGG Congress in San Francisco. Front Genet 2018; 9:362. [PMID: 30250480 PMCID: PMC6139345 DOI: 10.3389/fgene.2018.00362] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 08/21/2018] [Indexed: 12/17/2022] Open
Abstract
This article reviews research results and ideas presented at a special symposium at the International Association of Gerontology and Geriatrics (IAGG) Congress held in July 2017 in San Francisco. Five researchers presented their results related to infection and Alzheimer's disease (AD). Prof. Itzhaki presented her work on the role of viruses, specifically HSV-1, in the pathogenesis of AD. She maintains that although it is true that most people harbor HSV-1 infection, either latent or active, nonetheless aspects of herpes infection can play a role in the pathogenesis of AD, based on extensive experimental evidence from AD brains and infected cell cultures. Dr. Miklossy presented research on the high prevalence of bacterial infections that correlate with AD, specifically spirochete infections, which have been known for a century to be a significant cause of dementia (e.g., in syphilis). She demonstrated how spirochetes drive senile plaque formation, which are in fact biofilms. Prof. Balin then described the involvement of brain tissue infection by the Chlamydia pneumoniae bacterium, with its potential to use the innate immune system in its spread, and its initiation of tissue damage characteristic of AD. Prof. Fülöp described the role of AD-associated amyloid beta (Aβ) peptide as an antibacterial, antifungal and antiviral innate immune effector produced in reaction to microorganisms that attack the brain. Prof. Barron put forward the novel hypothesis that, according to her experiments, there is strong sequence-specific binding between the AD-associated Aβ and another ubiquitous and important human innate immune effector, the cathelicidin peptide LL-37. Given this binding, LL-37 expression in the brain will decrease Aβ deposition via formation of non-toxic, soluble Aβ/LL-37 complexes. Therefore, a chronic underexpression of LL-37 could be the factor that simultaneously permits chronic infections in brain tissue and allows for pathological accumulation of Aβ. This first-of-its-kind symposium opened the way for a paradigm shift in studying the pathogenesis of AD, from the "amyloid cascade hypothesis," which so far has been quite unsuccessful, to a new "infection hypothesis," or perhaps more broadly, "innate immune system dysregulation hypothesis," which may well permit and lead to the discovery of new treatments for AD patients.
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Affiliation(s)
- Tamàs Fülöp
- Department of Medicine, Division of Geriatrics, Research Center on Aging, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Ruth F. Itzhaki
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Brian J. Balin
- Department of Bio-Medical Sciences, Center for Chronic Disorders of Aging, Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
| | - Judith Miklossy
- International Alzheimer Research Centre, Prevention Alzheimer International Foundation, Martigny-Croix, Switzerland
| | - Annelise E. Barron
- Department of Bioengineering, Stanford University, Stanford, CA, United States
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Itzhaki RF, Lathe R, Balin BJ, Ball MJ, Bearer EL, Braak H, Bullido MJ, Carter C, Clerici M, Cosby SL, Del Tredici K, Field H, Fulop T, Grassi C, Griffin WST, Haas J, Hudson AP, Kamer AR, Kell DB, Licastro F, Letenneur L, Lövheim H, Mancuso R, Miklossy J, Otth C, Palamara AT, Perry G, Preston C, Pretorius E, Strandberg T, Tabet N, Taylor-Robinson SD, Whittum-Hudson JA. Microbes and Alzheimer's Disease. J Alzheimers Dis 2016; 51:979-84. [PMID: 26967229 DOI: 10.3233/jad-160152] [Citation(s) in RCA: 366] [Impact Index Per Article: 45.8] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Ruth F Itzhaki
- Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester, UK
| | - Richard Lathe
- Division of Infection and Pathway Medicine, University of Edinburgh, Little France, Edinburgh, UK
| | - Brian J Balin
- Center for Chronic Disorders of Aging, Philadelphia College of Osteopathic Medicine, Philadelphia, USA
| | - Melvyn J Ball
- Department of Pathology (Neuropathology), Oregon Health and Science University, Portland, OR, USA
| | - Elaine L Bearer
- Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Heiko Braak
- Clinical Neuroanatomy Section, Department of Neurology, Center for Biomedical Research, University of Ulm, Ulm, Germany
| | - Maria J Bullido
- Centro de Biologia Molecular 'Severo Ochoa' (CSIC-UAM), Universidad Autonoma de Madrid, and Centro de Investigacion en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Madrid, Spain
| | | | - Mario Clerici
- University of Milano and IRCCS SM Nascente, Don C Gnocchi Foundation, Milan, Italy
| | - S Louise Cosby
- Centre for Infection and Immunity, Medical Biology Centre, Queen's University, Belfast, UK
| | - Kelly Del Tredici
- Clinical Neuroanatomy Section, Department of Neurology, Center for Biomedical Research, University of Ulm, Ulm, Germany
| | | | - Tamas Fulop
- Department of Medicine, Division of Geriatrics, Université de Sherbrooke, Sherbrooke, PQ, Canada
| | - Claudio Grassi
- Institute of Human Physiology, Medical School, Universitá Cattolica, Rome; San Raffaele Pisana Scientific Institute for Research, Hospitalization, and Health Care, Rome, Italy
| | - W Sue T Griffin
- Department of Geriatrics, University of Arkansas for Medical Sciences, and Geriatric Research, Education, and Clinical Center, Little Rock, AR, USA
| | - Jürgen Haas
- Division of Infection and Pathway Medicine, University of Edinburgh, Little France, Edinburgh, UK
| | - Alan P Hudson
- Department of Immunology and Microbiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Angela R Kamer
- NYU College of Dentistry, Department of Periodontology and Implant Dentistry, New York, NY, USA
| | - Douglas B Kell
- School of Chemistry, Manchester Institute of Biotechnology, University of Manchester, Manchester, UK
| | - Federico Licastro
- Department of Experimental, Diagnostic, and Specialty Medicine, School of Medicine, University of Bologna, Bologna, Italy
| | | | - Hugo Lövheim
- Department of Community Medicine and Rehabilitation, Geriatric Medicine, Umeå University, Umeå, Sweden
| | | | - Judith Miklossy
- Prevention Alzheimer International Foundation, International Alzheimer Research Center, Martigny-Croix, Switzerland
| | - Carola Otth
- Institute of Clinical Microbiology, Faculty of Medicine, Austral University of Chile, Valdivia, Chile
| | - Anna Teresa Palamara
- Department of Public Health and Infectious Diseases, Institute Pasteur Cenci Bolognetti Foundation, Sapienza University of Rome; San Raffaele Pisana Scientific Institute for Research, Hospitalization, and Health Care, Rome, Italy
| | - George Perry
- College of Sciences, University of Texas at San Antonio, San Antonio, TX, USA
| | | | - Etheresia Pretorius
- Applied Morphology Research Centre, Department of Physiology, Faculty of Health Sciences, University of Pretoria, Arcadia, South Africa
| | - Timo Strandberg
- Helsinki University Hospital and University of Helsinki; University of Oulu, Centre of Life Course Health Research, Oulu, Finland
| | - Naji Tabet
- Division of Old Age Psychiatry, Brighton and Sussex Medical School, Brighton, UK
| | | | - Judith A Whittum-Hudson
- Departments of Immunology and Microbiology, Internal Medicine (Rheumatology), and Ophthalmology, Wayne State University School of Medicine, Detroit, MI, USA
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14
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Filardo S, Di Pietro M, Schiavoni G, Minniti G, Ortolani E, Romano S, Sessa R. Chlamydia pneumoniae Clinical Isolate from Gingival Crevicular Fluid: A Potential Atherogenic Strain. Front Cell Infect Microbiol 2015; 5:86. [PMID: 26636048 PMCID: PMC4659442 DOI: 10.3389/fcimb.2015.00086] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 11/13/2015] [Indexed: 12/17/2022] Open
Abstract
Chlamydia pneumoniae has been associated to atherosclerotic cardiovascular diseases. The aim of our study was to characterize, for the first time, a C. pneumoniae strain isolated from the gingival crevicular fluid of a patient with chronic periodontitis, described as a risk factor for cardiovascular diseases. C. pneumoniae isolate was characterized and compared to the respiratory AR-39 strain by VD4-ompA genotyping and by investigating the intracellular growth in epithelial and macrophage cell lines and its ability to induce macrophage-derived foam cells. Inflammatory cytokine levels were determined in the gingival crevicular fluid sample. C. pneumoniae isolate showed a 99% similarity with the AR-39 strain in the VD4-ompA gene sequence and shared a comparable growth kinetic in epithelial cells and macrophages, as evidenced by the infectious progeny and by the number of chlamydial genomic copies. C. pneumoniae isolate significantly increased the number of foam cells as compared to uninfected and LDL-treated macrophages (45 vs. 6%, P = 0.0065) and to the AR-39 strain (45 vs. 30%, P = 0.0065). Significantly increased levels of interleukin 1-β (2.1 ± 0.3 pg/μL) and interleukin 6 (0.6 ± 0.08 pg/μL) were found. Our results suggest that C. pneumoniae may harbor inside oral cavity and potentially be atherogenic, even though further studies will be needed to clarify the involvement of C. pneumoniae in chronic periodontitis as a risk factor for cardiovascular diseases.
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Affiliation(s)
- Simone Filardo
- Department of Public Health and Infectious Diseases, "Sapienza" University Rome, Italy
| | - Marisa Di Pietro
- Department of Public Health and Infectious Diseases, "Sapienza" University Rome, Italy
| | - Giovanna Schiavoni
- Department of Public Health and Infectious Diseases, "Sapienza" University Rome, Italy
| | - Gianluca Minniti
- General Dentistry and Emergency Care Unit, George Eastman Dental Hospital Rome, Italy
| | - Emanuela Ortolani
- General Dentistry and Emergency Care Unit, George Eastman Dental Hospital Rome, Italy
| | - Silvio Romano
- Department of Life, Health & Environmental Sciences, University of L'Aquila L'Aquila, Italy
| | - Rosa Sessa
- Department of Public Health and Infectious Diseases, "Sapienza" University Rome, Italy
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15
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Little CS, Joyce TA, Hammond CJ, Matta H, Cahn D, Appelt DM, Balin BJ. Detection of bacterial antigens and Alzheimer's disease-like pathology in the central nervous system of BALB/c mice following intranasal infection with a laboratory isolate of Chlamydia pneumoniae. Front Aging Neurosci 2014; 6:304. [PMID: 25538615 PMCID: PMC4257355 DOI: 10.3389/fnagi.2014.00304] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 10/18/2014] [Indexed: 12/28/2022] Open
Abstract
Pathology consistent with that observed in Alzheimer's disease (AD) has previously been documented following intranasal infection of normal wild-type mice with Chlamydia pneumoniae (Cpn) isolated from an AD brain (96-41). In the current study, BALB/c mice were intranasally infected with a laboratory strain of Cpn, AR-39, and brain and olfactory bulbs were obtained at 1-4 months post-infection (pi). Immunohistochemistry for amyloid beta or Cpn antigens was performed on sections from brains of infected or mock-infected mice. Chlamydia-specific immunolabeling was identified in olfactory bulb tissues and in cerebrum of AR-39 infected mice. The Cpn specific labeling was most prominent at 1 month pi and the greatest burden of amyloid deposition was noted at 2 months pi, whereas both decreased at 3 and 4 months. Viable Cpn was recovered from olfactory bulbs of 3 of 3 experimentally infected mice at 1 and 3 months pi, and in 2 of 3 mice at 4 months pi. In contrast, in cortical tissues of infected mice at 1 and 4 months pi no viable organism was obtained. At 3 months pi, only 1 of 3 mice had a measurable burden of viable Cpn from the cortical tissues. Mock-infected mice (0 of 3) had no detectable Cpn in either olfactory bulbs or cortical tissues. These data indicate that the AR-39 isolate of Cpn establishes a limited infection predominantly in the olfactory bulbs of BALB/c mice. Although infection with the laboratory strain of Cpn promotes deposition of amyloid beta, this appears to resolve following reduction of the Cpn antigen burden over time. Our data suggest that infection with the AR-39 laboratory isolate of Cpn results in a different course of amyloid beta deposition and ultimate resolution than that observed following infection with the human AD-brain Cpn isolate, 96-41. These data further support that there may be differences, possibly in virulence factors, between Cpn isolates in the generation of sustainable AD pathology.
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Affiliation(s)
- Christopher S. Little
- Department of Bio-Medical Sciences, Philadelphia College of Osteopathic MedicinePhiladelphia, PA USA
- Center for Chronic Disorders of Aging, Philadelphia College of Osteopathic MedicinePhiladelphia, PA, USA
| | - Timothy A. Joyce
- Department of Bio-Medical Sciences, Philadelphia College of Osteopathic MedicinePhiladelphia, PA USA
- Center for Chronic Disorders of Aging, Philadelphia College of Osteopathic MedicinePhiladelphia, PA, USA
| | - Christine J. Hammond
- Center for Chronic Disorders of Aging, Philadelphia College of Osteopathic MedicinePhiladelphia, PA, USA
- Division of Research, Philadelphia College of Osteopathic MedicinePhiladelphia, PA, USA
| | - Hazem Matta
- Center for Chronic Disorders of Aging, Philadelphia College of Osteopathic MedicinePhiladelphia, PA, USA
| | - David Cahn
- Center for Chronic Disorders of Aging, Philadelphia College of Osteopathic MedicinePhiladelphia, PA, USA
| | - Denah M. Appelt
- Department of Bio-Medical Sciences, Philadelphia College of Osteopathic MedicinePhiladelphia, PA USA
- Center for Chronic Disorders of Aging, Philadelphia College of Osteopathic MedicinePhiladelphia, PA, USA
| | - Brian J. Balin
- Department of Bio-Medical Sciences, Philadelphia College of Osteopathic MedicinePhiladelphia, PA USA
- Center for Chronic Disorders of Aging, Philadelphia College of Osteopathic MedicinePhiladelphia, PA, USA
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16
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Starr ME, Saito H. Sepsis in old age: review of human and animal studies. Aging Dis 2014; 5:126-36. [PMID: 24729938 PMCID: PMC3966671 DOI: 10.14336/ad.2014.0500126] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 12/17/2013] [Accepted: 12/18/2013] [Indexed: 12/12/2022] Open
Abstract
Sepsis is a serious problem among the geriatric population as its incidence and mortality rates dramatically increase with advanced age. Despite a large number of ongoing clinical and basic research studies, there is currently no effective therapeutic strategy that rescues elderly patients with severe sepsis. Recognition of this problem is relatively low as compared to other age-associated diseases. The disparity between clinical and basic studies is a problem, and this is likely due, in part, to the fact that most laboratory animals used for sepsis research are not old while the majority of sepsis cases occur in the geriatric population. The objective of this article is to review recent epidemiological studies and clinical observations, and compare these with findings from basic laboratory studies which have used aged animals in experimental sepsis.
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Affiliation(s)
- Marlene E Starr
- Department of Surgery, Lexington, KY 40536, USA
- Markey Cancer Center University of Kentucky, Lexington, KY 40536, USA
| | - Hiroshi Saito
- Department of Surgery, Lexington, KY 40536, USA
- Department of Physiology, Lexington, KY 40536, USA
- Markey Cancer Center University of Kentucky, Lexington, KY 40536, USA
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17
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Di Pietro M, Filardo S, De Santis F, Sessa R. Chlamydia pneumoniae infection in atherosclerotic lesion development through oxidative stress: a brief overview. Int J Mol Sci 2013; 14:15105-20. [PMID: 23877837 PMCID: PMC3742290 DOI: 10.3390/ijms140715105] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 07/04/2013] [Accepted: 07/10/2013] [Indexed: 12/11/2022] Open
Abstract
Chlamydia pneumoniae, an obligate intracellular pathogen, is known as a leading cause of respiratory tract infections and, in the last two decades, has been widely associated with atherosclerosis by seroepidemiological studies, and direct detection of the microorganism within atheroma. C. pneumoniae is presumed to play a role in atherosclerosis for its ability to disseminate via peripheral blood mononuclear cells, to replicate and persist within vascular cells, and for its pro-inflammatory and angiogenic effects. Once inside the vascular tissue, C. pneumoniae infection has been shown to induce the production of reactive oxygen species in all the cells involved in atherosclerotic process such as macrophages, platelets, endothelial cells, and vascular smooth muscle cells, leading to oxidative stress. The aim of this review is to summarize the data linking C. pneumoniae-induced oxidative stress to atherosclerotic lesion development.
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Affiliation(s)
- Marisa Di Pietro
- Department of Public Health and Infectious Diseases, “Sapienza” University, Rome 00185, Italy; E-Mails: (M.D.P.); (S.F.); (F.D.S.)
| | - Simone Filardo
- Department of Public Health and Infectious Diseases, “Sapienza” University, Rome 00185, Italy; E-Mails: (M.D.P.); (S.F.); (F.D.S.)
| | - Fiorenzo De Santis
- Department of Public Health and Infectious Diseases, “Sapienza” University, Rome 00185, Italy; E-Mails: (M.D.P.); (S.F.); (F.D.S.)
| | - Rosa Sessa
- Department of Public Health and Infectious Diseases, “Sapienza” University, Rome 00185, Italy; E-Mails: (M.D.P.); (S.F.); (F.D.S.)
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18
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Eddens T, Beaudoin S, Steinberger A, Little CS, Shell D, Wizel B, Balin B, Fresa-Dillon KL. Effect of age and vaccination on extent and spread of Chlamydia pneumoniae infection in C57BL/6 mice. IMMUNITY & AGEING 2012; 9:11. [PMID: 22594698 PMCID: PMC3410812 DOI: 10.1186/1742-4933-9-11] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 05/17/2012] [Indexed: 11/12/2022]
Abstract
Background Chlamydia pneumoniae is an obligate intracellular respiratory pathogen for humans. Infection by C. pneumoniae may be linked etiologically to extra-respiratory diseases of aging, especially atherosclerosis. We have previously shown that age promotes C. pneumoniae respiratory infection and extra-respiratory spread in BALB/c mice. Findings Aged C57BL/6 mice had a greater propensity to develop chronic and/or progressive respiratory infections following experimental intranasal infection by Chlamydia pneumoniae when compared to young counterparts. A heptavalent CTL epitope minigene (CpnCTL7) vaccine conferred equal protection in the lungs of both aged and young mice. This vaccine was partially effective in protecting against C. pneumoniae spread to the cardiovascular system of young mice, but failed to provide cardiovascular protection in aged animals. Conclusions Our findings suggest that vaccine strategies that target the generation of a C. pneumoniae-specific CTL response can protect the respiratory system of both young and aged animals, but may not be adequate to prevent dissemination of C. pneumoniae to the cardiovascular system or control replication in those tissues in aged animals.
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Affiliation(s)
- Taylor Eddens
- Department of Pathology, Microbiology, and Immunology, the Philadelphia College of Osteopathic Medicine, 4170 City Avenue, Philadelphia, PA, 19131, USA.
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19
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Chlamydia pneumoniae infection enhances microglial activation in atherosclerotic mice. Neurobiol Aging 2010; 31:1766-73. [DOI: 10.1016/j.neurobiolaging.2008.09.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Revised: 09/14/2008] [Accepted: 09/30/2008] [Indexed: 11/22/2022]
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Hammond CJ, Hallock LR, Howanski RJ, Appelt DM, Little CS, Balin BJ. Immunohistological detection of Chlamydia pneumoniae in the Alzheimer's disease brain. BMC Neurosci 2010; 11:121. [PMID: 20863379 PMCID: PMC2949767 DOI: 10.1186/1471-2202-11-121] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Accepted: 09/23/2010] [Indexed: 01/08/2023] Open
Abstract
Background Sporadic late-onset Alzheimer's disease (AD) appears to evolve from an interplay between genetic and environmental factors. One environmental factor that continues to be of great interest is that of Chlamydia pneumoniae infection and its association with late-onset disease. Detection of this organism in clinical and autopsy samples has proved challenging using a variety of molecular and histological techniques. Our current investigation utilized immunohistochemistry with a battery of commercially available anti-C. pneumoniae antibodies to determine whether C. pneumoniae was present in areas typically associated with AD neuropathology from 5 AD and 5 non-AD control brains. Results Immunoreactivity for C. pneumoniae antigens was observed both intracellularly in neurons, neuroglia, endothelial cells, and peri-endothelial cells, and extracellularly in the frontal and temporal cortices of the AD brain with multiple C. pneumoniae-specific antibodies. This immunoreactivity was seen in regions of amyloid deposition as revealed by immunolabeling with two different anti-beta amyloid antibodies. Thioflavin S staining, overlaid with C. pneumoniae immunolabeling, demonstrated no direct co-localization of the organism and amyloid plaques. Further, the specificity of C. pneumoniae labeling of AD brain sections was demonstrated using C. pneumoniae antibodies pre-absorbed against amyloid β 1-40 and 1-42 peptides. Conclusions Anti-C. pneumoniae antibodies, obtained commercially, identified both typical intracellular and atypical extracellular C. pneumoniae antigens in frontal and temporal cortices of the AD brain. C. pneumoniae, amyloid deposits, and neurofibrillary tangles were present in the same regions of the brain in apposition to one another. Although additional studies are required to conclusively characterize the nature of Chlamydial immunoreactivity in the AD brain, these results further implicate C. pneumoniae infection with the pathogenesis of Alzheimer's disease.
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Affiliation(s)
- Christine J Hammond
- Pathology/Microbiology/Immunology and Forensic Medicine Department, Philadelphia College of Osteopathic Medicine, 4170 City Ave, Philadelphia, Pennsylvania, USA.
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21
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Shima K, Kuhlenbäumer G, Rupp J. Chlamydia pneumoniae infection and Alzheimer's disease: a connection to remember? Med Microbiol Immunol 2010; 199:283-9. [PMID: 20445987 DOI: 10.1007/s00430-010-0162-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Indexed: 12/30/2022]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia in the elderly, whereby it is customary to distinguish between early familial FAD and late-onset AD (LOAD). The development of LOAD, the most prevalent form of AD, is believed to be a multifactorial process that may also involve infections with bacterial or viral pathogens. After the first report on the presence of Chlamydia pneumoniae (Cpn) in brains of patients with AD appeared in 1998, this bacterium has most often been implicated in AD pathogenesis. However, while some studies demonstrate a clear association between Cpn infection and AD, others have failed to confirm these findings. This might be due to heterogeneity of the specimens analyzed and lack of standardized detection methods. Additionally, non-availability of suitable chlamydial infection models severely hampers research in the field. In this review, we will critically discuss the possible role of Cpn in the pathogenesis of LOAD in light of the available data. We will also present three mutually non-exclusive hypotheses how Cpn might contribute to the pathogenesis of AD.
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Affiliation(s)
- Kensuke Shima
- Institute of Medical Microbiology and Hygiene, University of Lübeck, Lübeck, Germany
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22
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Boelen E, Steinbusch HWM, Pronk I, Grauls G, Rennert P, Bailly V, Bruggeman CA, Stassen FRM. Inflammatory responses following Chlamydia pneumoniae infection of glial cells. Eur J Neurosci 2007; 25:753-60. [PMID: 17313571 DOI: 10.1111/j.1460-9568.2007.05339.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recently, infections have been implicated in the pathogenesis of Alzheimer's disease. Apart from the direct effects of pathogens, it can be hypothesized that inflammatory mechanisms, such as the production of pro-inflammatory mediators by resident glia, may result in neurotoxicity. Here, we examined the inflammatory responses in murine microglial cell (MMC) and murine astrocyte cell (MAC) lines following infection with Chlamydia pneumoniae (Cpn), a pathogen that has recently been associated with Alzheimer's disease. Furthermore, we determined whether these inflammatory responses are sufficient to cause neuronal cell death in vitro. MMCs and MACs were infected with Cpn. Subsequently, various chemo- and cytokines were determined in the culture supernatant fluid of infected/control cells at different time points post-infection. Significantly higher levels of monocyte chemoattractant protein 1, interleukin (IL)-6, tumour necrosis factor (TNF)-alpha and IL-1beta were found in supernatant fluids of infected MMCs compared with controls. In contrast, in the supernatant fluid of infected MACs, only monocyte chemoattractant protein 1 and IL-6 displayed significantly higher levels compared with controls. Moreover, neurotoxicity was examined up to 72 h after transferring the conditioned supernatant fluid to a neuronal cell layer. No neuronal cell death was observed when supernatant fluids from infected/mock-treated MACs were transferred. However, when neurones were exposed to conditioned supernatant fluid from infected MMCs, a significant increase in cell death was observed compared with mock. Furthermore, adding neutralizing antibodies against IL-6 and TNF-alpha to that conditioned supernatant fluid prevented neuronal cell death by approximately 50%. In conclusion, these data suggest that Cpn infection results in a pro-inflammatory milieu, particularly by activating MMCs, that ultimately results in neurodegeneration with prominent roles for both IL-6 and TNF-alpha.
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Affiliation(s)
- E Boelen
- Department of Medical Microbiology, Cardiovascular Research Institute Maastricht, Maastricht University, PO Box 616, 6200 MD Maastricht, The Netherlands
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Monaghan RL, Barrett JF. Antibacterial drug discovery—Then, now and the genomics future. Biochem Pharmacol 2006; 71:901-9. [PMID: 16494849 DOI: 10.1016/j.bcp.2005.11.023] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2005] [Revised: 11/18/2005] [Accepted: 11/24/2005] [Indexed: 11/17/2022]
Abstract
Drug discovery research in the area of infectious diseases, in particular that dealing with antibacterial/antibiotic susceptibility and resistance, is in a process of continuing evolution. Steeped in the history of the highly successful intervention with chemotherapeutic agents to treat human infections, the emergence of drug-resistant pathogens worldwide presents a serious unmet medical need, if not a pending catastrophe. Research in both academia and industry over the past 30 years using molecular biology, genetics and more recently--bacterial genomics--has assembled key enabling technologies to increase productivity and success rates in the discovery and development of novel antibacterial agents. However genomics is not limited only to antibacterial target selection but provides the opportunity to further understand key interactions in the use of antibacterial compounds as therapeutic agents (such as resistance emergence, susceptibility, efflux, interactions between compound and pathogen, etc.). Genomics also offers the potential for insights into: bacterial niche adaptation, host susceptibility, treatment regimens, antibiotic resistance, pharmacokinetics (e.g., host metabolism differences), safety and the microbial genesis of chronic diseases (e.g., gastric ulceration).
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Affiliation(s)
- Richard L Monaghan
- Merck Research Laboratories, 126 E. Lincoln Avenue, Rahway, NJ 07065, USA.
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