Chlamydia pneumoniae can infect the central nervous system via the olfactory and trigeminal nerves and contributes to Alzheimer’s disease risk

Chacko, Anu; Delbaz, Ali; Walkden, Heidi; Basu, Souptik; Armitage, Charles W.; Eindorf, Tanja; Trim, Logan K; Miller, Edith; West, Nicholas P.; John, James Anthony St; Beagley, Kenneth W.; Ekberg, Jenny

doi:10.1038/s41598-022-06749-9

Cited by 36 publications

(36 citation statements)

References 91 publications

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“…The fact that GM dysbiosis can contribute to AD pathogenesis strengthens the idea that sporadic late onset AD (LOAD) may have an infectious etiology is the case for infection driven by neurotropic viruses such as Human herpesvirus 1, bacteria such as Chlamydia pneumoniae, or fungi such as Candida albicans (44)(45)(46). However, it is also known that LPS, the major component of a Gram-negative bacteria cell wall, can interact with the TLRs (such as TLR2 and TLR4) expressed on both microglial cells and the intestinal epithelium (47), providing a link between the immune system, PRRs, and the ability to recognize micro-organism-associated molecular patterns.…”

Section: Connecting Gut Microbial Dysbiosis To Alzheimer's Disease Pa...mentioning

confidence: 84%

Alzheimer’s disease and depression in the elderly: A trajectory linking gut microbiota and serotonin signaling

et al. 2022

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The occurrence of neuropsychiatric symptoms in the elderly is viewed as an early sign of subsequent cognitive deterioration and conversion from mild cognitive impairment to Alzheimer’s disease. The prognosis in terms of both the severity and progression of clinical dementia is generally aggravated by the comorbidity of neuropsychiatric symptoms and decline in cognitive function. Undeniably, aging and in particular unhealthy aging, is a silent “engine of neuropathology” over which multiple changes take place, including drastic alterations of the gut microbial ecosystem. This narrative review evaluates the role of gut microbiota changes as a possible unifying concept through which the comorbidity of neuropsychiatric symptoms and Alzheimer’s disease can be considered. However, since the heterogeneity of neuropsychiatric symptoms, it is improbable to describe the same type of alterations in the bacteria population observed in patients with Alzheimer’s disease, as well as it is improbable that the variety of drugs used to treat neuropsychiatric symptoms might produce changes in gut bacterial diversity similar to that observed in the pathophysiology of Alzheimer’s disease. Depression seems to be another very intriguing exception, as it is one of the most frequent neuropsychiatric symptoms in dementia and a mood disorder frequently associated with brain aging. Antidepressants (i.e., serotonin reuptake inhibitors) or tryptophan dietary supplementation have been shown to reduce Amyloid β-loading, reinstate microbial diversity and reduce the abundance of bacterial taxa dominant in depression and Alzheimer’s disease. This review briefly examines this trajectory by discussing the dysfunction of gut microbiota composition, selected bacterial taxa, and alteration of tryptophan and serotonin metabolism/neurotransmission as overlapping in-common mechanisms involved with depression, Alzheimer’s disease, and unhealthy aging.

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Section: Connecting Gut Microbial Dysbiosis To Alzheimer's Disease Pa...mentioning

confidence: 84%

Alzheimer’s disease and depression in the elderly: A trajectory linking gut microbiota and serotonin signaling

et al. 2022

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“…Recent studies have provided overwhelming evidence about the possibility of an infectious etiology for AD. The infiltration of the brain by pathogens, including but not limited to B. fragilis, HSV-type 1, Chlamydia pneumoniae , and P. gingivalis , is most frequently implicated in AD pathogenesis [ 204 , 222 , 223 , 224 , 225 , 226 , 227 ]. These pathogens may directly cross a weakened blood–brain barrier and trigger neurological damage by eliciting neuroinflammation.…”

Section: Multiple Strategies To Optimize Brain Healthmentioning

confidence: 99%

Rationale for a Multi-Factorial Approach for the Reversal of Cognitive Decline in Alzheimer’s Disease and MCI: A Review

Rao¹,

Subramaniam

Gregory³

et al. 2023

IJMS

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Alzheimer’s disease (AD) is a multifactorial, progressive, neurodegenerative disease typically characterized by memory loss, personality changes, and a decline in overall cognitive function. Usually manifesting in individuals over the age of 60, this is the most prevalent type of dementia and remains the fifth leading cause of death among Americans aged 65 and older. While the development of effective treatment and prevention for AD is a major healthcare goal, unfortunately, therapeutic approaches to date have yet to find a treatment plan that produces long-term cognitive improvement. Drugs that may be able to slow down the progression rate of AD are being introduced to the market; however, there has been no previous solution for preventing or reversing the disease-associated cognitive decline. Recent studies have identified several factors that contribute to the progression and severity of the disease: diet, lifestyle, stress, sleep, nutrient deficiencies, mental health, socialization, and toxins. Thus, increasing evidence supports dietary and other lifestyle changes as potentially effective ways to prevent, slow, or reverse AD progression. Studies also have demonstrated that a personalized, multi-therapeutic approach is needed to improve metabolic abnormalities and AD-associated cognitive decline. These studies suggest the effects of abnormalities, such as insulin resistance, chronic inflammation, hypovitaminosis D, hormonal deficiencies, and hyperhomocysteinemia, in the AD process. Therefore a personalized, multi-therapeutic program based on an individual’s genetics and biochemistry may be preferable over a single-drug/mono-therapeutic approach. This article reviews these multi-therapeutic strategies that identify and attenuate all the risk factors specific to each affected individual. This article systematically reviews studies that have incorporated multiple strategies that target numerous factors simultaneously to reverse or treat cognitive decline. We included high-quality clinical trials and observational studies that focused on the cognitive effects of programs comprising lifestyle, physical, and mental activity, as well as nutritional aspects. Articles from PubMed Central, Scopus, and Google Scholar databases were collected, and abstracts were reviewed for relevance to the subject matter. Epidemiological, pathological, toxicological, genetic, and biochemical studies have all concluded that AD represents a complex network insufficiency. The research studies explored in this manuscript confirm the need for a multifactorial approach to target the various risk factors of AD. A single-drug approach may delay the progression of memory loss but, to date, has not prevented or reversed it. Diet, physical activity, sleep, stress, and environment all contribute to the progression of the disease, and, therefore, a multi-factorial optimization of network support and function offers a rational therapeutic strategy. Thus, a multi-therapeutic program that simultaneously targets multiple factors underlying the AD network may be more effective than a mono-therapeutic approach.

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“…On one hand, activated microglia reduce the accumulation of Aβ in the brain by increasing their phagocytosis, clearance, and degradation. On the other hand, the continuous activation of microglia caused by their binding to Aβ can increase the production of inflammatory mediators, which further amplifies the neuroinflammatory response, leading to chronic inflammation and AD [ 95 , 96 , 97 , 98 ] ( Figure 4 ).…”

Section: Research Progress Of Nrf2 In Inflammation-related Diseasesmentioning

confidence: 99%

Clinical Research Progress of Small Molecule Compounds Targeting Nrf2 for Treating Inflammation-Related Diseases

et al. 2022

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Studies have found that inflammation is a symptom of various diseases, such as coronavirus disease 2019 (COVID-19) and rheumatoid arthritis (RA); it is also the source of other diseases, such as Alzheimer’s disease (AD), Parkinson’s disease (PD), lupus erythematosus (LE), and liver damage. Nrf2 (nuclear factor erythroid 2-related factor 2) is an important multifunctional transcription factor in cells and plays a central regulatory role in cellular defense mechanisms. In recent years, several studies have found a strong association between the activation of Nrf2 and the fight against inflammation-related diseases. A number of small molecule compounds targeting Nrf2 have entered clinical research. This article reviews the research status of small molecule compounds that are in clinical trials for the treatment of COVID-19, rheumatoid arthritis, Alzheimer’s disease, Parkinson’s disease, lupus erythematosus, and liver injury.

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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

Cited by 36 publications

References 91 publications

Alzheimer’s disease and depression in the elderly: A trajectory linking gut microbiota and serotonin signaling

Alzheimer’s disease and depression in the elderly: A trajectory linking gut microbiota and serotonin signaling

Rationale for a Multi-Factorial Approach for the Reversal of Cognitive Decline in Alzheimer’s Disease and MCI: A Review

Clinical Research Progress of Small Molecule Compounds Targeting Nrf2 for Treating Inflammation-Related Diseases

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