TLR4 and colitis: Similarly, E. coli Nissle 1917 ameliorated dextran sulfate-induced colitis and decreased the pro-inflammatory cytokine response in wild-type mice, but not in TLR2 or TLR4 knockout mice [90], which supports E. coli Nissle 1917 immunomodulation of host TLR2 and TLR4 signaling.