CD4 and colitis: The novel data herein revealed that the interaction existed among MSCs, host, and gut bacteria in the suppression of colitis, namely, MSCs alleviated colon inflammation in a gut microbiota-dependent manner and meanwhile in untangling this tripartite mechanism of inhibiting colitis we noted that microbiota-derived metabolites SCFAs displayed the critical role in mediating MSCs restoring CD4+T cell immune homeostasis.