Given B cells, which have high TLR9 expression (40–42), are one of the major mucosal immune cells and gut microbiota’s potential pathogenic role in T1D (16, 43–45), we hypothesized that gut microbiota induce IL-10 elevation in B cell-specific TLR9-deficient NOD mice. The gene discussed is TLR9; the disease is type 1 diabetes mellitus.