Exploring the Mechanisms of Multiple Sclerosis and The Role of Intestinal Microbiota Dysbiosis – A Comprehensive Scoping Literature Review of Pathogenic Mechanisms

Abstract

Multiple sclerosis (MS) is a chronic inflammatory neurodegenerative disorder that damages myelin in the central nervous system through autoimmune attacks leading to neurological disability in young adults. Research shows that changes in gut microbiota may influence the development of MS with limited clinical evidence. This scoping literature review analyzed the relationship between intestinal microbiota and its effects on MS progression and disease course and activity. Following PRISMA-ScR guidelines, multiple databases were searched. Sixteen studies with 1,052 MS patients and 690 healthy controls from 12 countries were analyzed. Most studies (81%) used crosssectional design; most participants (70%) were female with relapsing-remitting MS (70.5%). Analysis of microbial diversity produced no uniform results, but specific taxonomic changes were detected. SCFA-producing bacteria including Bacteroidota, Roseburia inulinivorans, and Bifidobacterium were present at lower levels in MS patients, but their presence was associated with improved clinical results. The species Clostridium and Collinsella aerofaciens linked to negative results and higher disability scores. Studies revealed SCFA levels dropped significantly in MS patients with major decreases in butyrate. This review shows MS patients have persistent gut microbiota imbalance involving decreased SCFA-producing bacteria instead of overall diversity changes, identifying gut microbiome changes as a major factor leading to MS progression. Future research needs to study MS-related microbiomes for diagnostic and therapeutic applications by studying their characteristics and modification methods.