TLR4 and colitis: In contrast to conventionally raised mice, ABX(WT) mice and ABX(TLR4−/−) mice showed indistinguishable body weight loss (Fig. 1d), mortality (Fig. 1e), DAI score (Fig. 1f), colon length (Fig. 1g and h), histology score (Fig. 1i and j), and colonoscopy score (Fig. 1k and l) following DSS treatment, indicating a role of gut microbiota in the severe colitis observed in TLR4−/− mice.