Normal human colonic subepithelial myofibroblasts enhance epithelial migration (restitution) via TGF-beta 3

After injury and loss of epithelial cells, intestinal barrier function is r eestablished by migration of viable epithelial cells from the wound edge (r estitution). Myofibroblasts are located close to the basal surface of epith elial cells. This study aimed to investigate the role of human colonic sube pithelial myofibroblasts in epithelial restitution. Primary cultures of sub epithelial myofibroblasts were established. Monolayers' of the epithelial c ell lines IEC-6 and T84 were "wounded" in a standard manner to create an in vitro model of restitution. Migration of epithelial cells across the wound edge was assessed following culture in myofibroblast-conditioned medium. M yofibroblast expression of transforming growth factor (TGF)-beta isoforms w as examined using RT-PCR, and TGF-beta isoform bioactivity was assessed usi ng My 1 Lu bioassay. Myofibroblast-conditioned medium, via a TGF-beta-depen dent pathway, significantly enhanced migration of epithelial cells across t he wound edge and significantly inhibited cell proliferation in wounded mon olayers. Messenger RNA for TGF-beta 1, -beta 2, and -beta 3 was detected in the myofibroblasts, and My 1 Lu bioassay showed the presence of predominan tly bioactive TGF-beta 3. This study shows that human colonic subepithelial myofibroblasts secrete predominantly bioactive TGF-beta 3 and enhance rest itution in wounded epithelial monolayers via a TGF-beta-dependent pathway.