Erysipelotrichaceae bacterium OTU0002 isolated from mouse small intestine

Accumulating evidence indicates that gut microbes play a pathogenic role in autoimmune diseases including multiple sclerosis (MS). Here, we show that two distinct signals from gut microbes coordinately activate myelin oligodendrocyte glycoprotein (MOG)-specific autoreactive T cells in the small intestine (SI). After induction of experimental autoimmune encephalomyelitis (EAE), an animal model for MS, MOG-specific CD4 T cells can be observed in the SI. Germ-free (GF) mice monocolonized with SI microbes demonstrated that a newly isolated Erysipelotrichaceae strain adheres to SI epithelial cells and enhances Th17 responses, via inducing serum amyloid A and IL-23, that were associated with an increased susceptibility to EAE. Shotgun sequencing of SI contents revealed that a Lactobacillus strain possesses potential mimicry peptides to MOG. While monocolonization of GF mice with the Lactobacillus strain did not enhance EAE development or severity, co-colonized mice with Erysipelotrichaceae and Lactobacillus strains resulted in more severe EAE.