The Role of the Gut Microbiota in the Pathogenesis of Parkinson's Disease

Abstract

It is well-recognized that the gut microbiota (GM) is crucial for gut function, metabolism, and energy cycles. The GM also has effects on neurological outcomes via many mechanisms, such as metabolite production and the gut-brain axis. Emerging evidence has gradually indicated that GM dysbiosis plays a role in several neurological diseases, such as Parkinson's disease (PD), Alzheimer's disease, depression, and multiple sclerosis. Several studies have observed that PD patients generally suffer from gastrointestinal disorders and GM dysbiosis prior to displaying motor symptoms, but the specific link between the GM and PD is not clearly understood. In this review, we aim to summarize what is known regarding the correlation between the GM and PD pathologies, including direct, and indirect evidence.

Meta‐Analysis of Gut Dysbiosis in Parkinson's Disease

“…31 Gut microbiota in PD has been addressed in 16 original articles and one abstract (Supporting Information Table S1) 27,[32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] and also has been reviewed. 3,48,49 Gut microbiota, however, differ from country to country in composition even among normal subjects, 50 which makes it difficult to compare PD and controls across countries. In order to identify differences in bacterial taxa in PD across countries, we performed 16S ribosomal RNA (rRNA) gene sequencing of fecal samples from 223 PD patients and 137 controls and, subsequently, conducted a meta-analysis of the dataset we generated and four datasets from other countries.…”

Is Porphyromonas gingivalis involved in Parkinson’s disease?

“…Intestinal bacteria may also be involved in PD where the role of the gut-brain-microbiota axis has been emphasized [44][45][46][47][48][49]. However, this does not exclude involvement of oral bacteria since an oral-brain-microbiota axis may exist, as suggested recently for patients with autism spectrum disorder (ASD) [50].…”

Faecal microbiota transplantation simultaneously ameliorated patient's essential tremor and irritable bowel syndrome

“…A previous study showed that dysfunction of the microbiota‐gut‐brain axis might lead to neurological disease, 1 and increasing evidence indicates a potential bidirectional relationship between gut microbiota and neurological disease. For example, gut microbiota is involved in motor deficits, microglia activation, and pathology, which play important roles in the development of Parkinson's disease 2 . Exchanging gut microbiota can reduce the expression of brain‐derived neurotrophic factor in the brain 3 …”

“…For example, gut microbiota is involved in motor deficits, microglia activation, and pathology, which play important roles in the development of Parkinson's disease. 2 Exchanging gut microbiota can reduce the expression of brainderived neurotrophic factor in the brain. 3 Faecal microbiota transplantation (FMT) is a microbiota-targeted therapy.…”