TNFAIP6 and colitis: In expounding the mechanism involved in MSC and macrophage interaction in ameliorating colitis, Song and colleagues report that both human and canine adipose tissue-derived MSCs administered intraperitoneally secrete TSG-6 (tumor necrosis factor-α-induced gene/protein 6) which induces macrophage phenotypic switch from M1 to M2 [17, 18].