Background & aims: Transforming growth factors (TGFs) alpha and beta are key regulatory peptides that modulate mucosal cell populations critical to inflammatory bowel disease. The aim of this study was to assess TGF-alpha and TGF-beta expression in human colonic mucosa.
Methods: TGF-alpha and TGF-beta expression was assessed in colonic mucosa from patients with ulcerative colitis, patients with Crohn's disease, and controls by Northern blot analysis, in situ hybridization, and bioassay.
Results: TGF-alpha messenger RNA expression localized to the villous tips of the small intestine and the surface epithelium of the colon. TGF-alpha expression was enhanced 2.3-fold in inactive ulcerative colitis mucosa relative to active ulcerative colitis, Crohn's disease, or normal controls. Enhanced expression correlated with duration of disease. TGF-beta expression was increased in affected mucosa from both patients with ulcerative colitis and Crohn's disease with active disease. TGF-beta1 messenger RNA expression in ulcerative colitis and Crohn's disease localized mostly to cells of the lamina propria with the highest concentration in inflammatory cells closest to the luminal surface.
Conclusions: TGF-alpha may contribute to epithelial hyperproliferation and the increased risk of malignancy in long-standing ulcerative colitis. TGF-beta may be a key cytokine during periods of active inflammation, modulating epithelial cell restitution and functional features of cells within the lamina propria.