IL33 and irritable bowel syndrome: Kinchen et al. found that the pro-inflammatory factor IL-33, one of the markers of the S4 subpopulation of intestinal mesenchymal cells, which activates in dysregulation of niche in IBD, exhibits increased expression in the intestinal mucosal tissue of both human and mouse patients with IBD, and induced factors that impaired epithelial proliferation and maturation and contributed to oxidative stress and disease severity in vivo (Kinchen et al., 2018).