CLDN2 and colitis: Importantly, the weakened gut barrier in the colitis mice markedly recovered after transplantation of the SH‐modulated gut microbiota, as reflected by the upregulated expression of Occludin, Claudin‐2, Claudin‐3, and Claudin‐4 mRNAs and Occludin, Claudin‐3, and Claudin‐4 proteins (Figures 2I and S6C).