The Gut and Multiple Sclerosis: Dysbiosis as a trigger or autoimmune reflex?

Abstract

Introduction. Multiple Sclerosis (MS) is the primary demyelinating disease and the second leading cause of disability in young adults in developed countries. It is an immune-mediated neurodegenerative disease characterized by diverse symptoms, and its diagnosis is established through clinical presentation, imaging studies, cerebrospinal fluid analysis, and exclusion of other causes. The etiology of the disease remains uncertain, but several factors may be involved, including dysregulation of the intestinal microbiome. Objective. This review aims to gather studies from scientific platforms to elucidate the gut-MS relationship. Method. For this systematic review, the descriptors "Gastrointestinal Microbiome" and "Multiple Sclerosis" were used in the MEDLINE/PUBMED database, resulting in 13 articles, from which inclusion and exclusion criteria were applied, with 11 studies included in the review. Results. Microbial metabolites such as short-chain fatty acids and tryptophan metabolites suppress autoimmunity by increasing regulatory T cells and influencing immune cell metabolism. Furthermore, it was evidenced that the microbiota modulates mucosa-associated lymphoid tissue (GALT), thereby affecting tissue composition and influencing autoimmune responses. Conclusion. Studies suggest significant roles of the microbiome and intestinal immunity in the development of autoimmune diseases such as MS. However, knowledge regarding the effects of intestinal bacterial composition associated with the disease remains limited.