TLR9 and colitis: Mice lacking common viruses or MAVS are more likely to develop dextran sulfate sodium (DSS)-induced colitis, and restoring IELs in these mice through IL-15 supplementation reduces susceptibility to DSS.80 Gogokhia L et al. (2019) showed that Lactobacillus phage, E. coli phage, and Bacteroidetes phages stimulated interferon-gamma (IFN-γ) production through the nucleotide sensing receptor TLR9.