No alteration of gut microbiota in patients with myasthenia gravis compared to control patients: results from the MYBIOM trial. Gut microbiota in patients with myasthenia gravis

Background: Myasthenia gravis (MG) is an autoimmune neuromuscular disease, and gut microbiota have been considered a possible pathogenetic factor. Currently, studies have found differences in the gut microbiota of MG patients and healthy individuals. This study compared gut microbiota of MG patients to patients with non-inflammatory neurological disorders and to patients with other autoimmune disease of the peripheral nervous system in addition to healthy volunteers.Methods: Fecal samples of MG patients (n=41), control patients with non-inflammatory neurological disorders (n=18), patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP, n=6), and healthy volunteers (n=12) were collected, DNA was isolated, and the variable regions of the 16S rRNA gene were sequenced and statistically analyzed. Results: There was no differences in alpha- and beta-diversity displaying an unaltered bacterial diversity and structure of the microbial community between the MG group, the patients with non-inflammatory neurological disorders, and the CIDP group. Between the MG group and the healthy volunteers, alpha-diversity indices Shannon, Simpson, Chao 1 and ACE were significantly reduced. Within the fecal microbiota of MG patients, Deltaproteobacteria and Faecalibacterium were more abundant compared to controls with non-inflammatory diseases.Conclusions: Although the overall bacterial diversity and structure did not differ between the MG group compared to non-inflammatory and inflammatory neurological disorders, the significant difference in the abundance of Deltaproteobacteria and Faecalibacterium supports the considered role of gut microbiota as a possible contributor to MG pathogenesis. Further studies will be helpful to confirm these findings and to develop possible treatment strategies i.e. antibiotics.