The role of the gut microbiota in the pathogenesis of myasthenia gravis

Myasthenia gravis is an autoimmune neuromuscular disorder in which antibodies against acetylcholine receptor or muscle-specific kinase impair neuromuscular transmission and lead to fluctuating muscle weakness. Recent evidence indicates that the gut microbiota is an important environmental factor capable of modulating systemic immunity and influencing the risk of autoantibody formation. Patients with myasthenia gravis demonstrate reduced microbial diversity, depletion of butyrate-producing taxa and expansion of pro-inflammatory bacteria, which correlate with an imbalance between regulatory T cells and Th17 cells, increased intestinal permeability and activation of complement. Experimental models show that transfer of dysbiotic microbiota can worsen disease severity, whereas restoration of short-chain fatty acid production mitigates autoimmune responses. Integrating data from human studies, animal experiments and Mendelian randomization, the gut–muscle axis is now regarded as a potential therapeutic target. Microbiota-directed interventions such as dietary fiber enrichment, targeted probiotics, butyrate supplementation and fecal microbiota transplantation may complement standard immunotherapy and support personalized management strategies for patients with myasthenia gravis.