Healthy Gut, Healthy Brain: The Gut Microbiome in Neurodegenerative Disorders

Abstract

Background: The central nervous system (CNS) known to regulate the physiological conditions of human body, also itself gets dynamically regulated by both the physiological as well as pathological conditions of the body. These conditions get changed quite often, and often involve changes introduced into the gut microbiota which, as studies are revealing, directly modulate the CNS via a crosstalk. This cross-talk between the gut microbiota and CNS, i.e., the gut-brain axis (GBA), plays a major role in the pathogenesis of many neurodegenerative disorders such as Parkinson’s disease (PD), Alzheimer’s disease (AD), amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS) and Huntington’s disease (HD). Objective: We aim to discuss how gut microbiota, through GBA, regulate neurodegenerative disorders such as PD, AD, ALS, MS and HD. Methods: In this review, we have discussed the present understanding of the role played by the gut microbiota in neurodegenerative disorders and emphasized the probable therapeutic approaches being explored to treat them. Results: In the first part, we introduce the GBA and its relevance, followed by the changes occurring in the GBA during neurodegenerative disorders and then further discuss its role in the pathogenesis of these diseases. Finally, we discuss its applications in possible therapeutics of these diseases and the current research improvements being made to better investigate this interaction. Conclusion: We concluded that alterations in the intestinal microbiota modulate various activities that could potentially lead to CNS disorders through interactions via the GBA.

Dysregulation of the Gut-Brain Axis, Dysbiosis and Influence of Numerous Factors on Gut Microbiota Associated Parkinson’s Disease

“…BBB-permeable substances typically have minimal or no charge with low molecular weight and posses lipid-soluble characteristics. It has been shown by various studies that intestinal metabolic products manifest these features, which allow easy entry to modify brain physiology via the BBB [ 110 - 114 ]. Modulations in the BBB and intestinal permeability, microbial dysbiosis, and intestinal epithelial barrier permeability or dysfunction were reported as essential mechanisms for PD progression.…”

Warm, Sweetened Milk at the Twilight of Immunity - Alzheimer’s Disease - Inflammaging, Insulin Resistance, M. paratuberculosis and Immunosenescence

“…There is a bi-directional communication, a crosstalk, between the gut microbiota and CNS; the gut-brain-microbiome axis is increasingly understood to play a major role in the pathogenesis of many neurodegenerative disorders including Alzheimer's disease (AD) (29).…”

Gut microbial imbalance and neurodegenerative proteinopathies: from molecular mechanisms to prospects of clinical applications

“…Besides essential or beneficial microbiota, gut is colonized permanently or occasionally by bacteria that can become opportunistic pathogens if the occasion arise [24]. Therefore, the pathological imbalance of the optimal gut microbiota composition, named dysbiosis, leads to an overgrowth of harmful bacteria and ultimately to a disruption of the host-microorganism homeostasis [25][26][27].…”