Reduced susceptibility of mice overexpressing transforming growth factor alpha to dextran sodium sulphate induced colitis.

Background—Transforming growth factor AE (TGF-AE) knockout mice have increased susceptibility to dextran sodium sulphate (DSS) induced colitis. Aim—To substantiate the findings that TGF-AE is a key mediator of colonic mucosal protection and/or repair mechanisms by evaluating the susceptibility of mice overexpressing TGF-AE to DSS induced colitis. Methods—TGF-AE overexpression was induced in transgenic mice by ZnSO4 administration in drinking water (TG+). Three groups were used as controls: one transgenic group without ZnSO4 administration (TG˛), and two non-transgenic littermate groups receiving ZnSO4 (NonTG+) or only water (Non-TG˛). Acute colitis was induced in all groups by administration of DSS (5%, w/v) in drinking water for six days ad libitum. Results—About 35‐39% of the entire colonic mucosa was destroyed in Non-TG˛, Non-TG+, and TG˛ animals compared with 9% in TG+ mice. The crypt damage score was 18.7 (0.9), 18.2 (1.0), 18.9 (0.8), and 6.8 (1.5) (means (SEM)) in Non-TG˛, Non-TG+, TG˛, and TG+ mice respectively. Mucin and bromodeoxyuridine staining were markedly enhanced in colons of TG+ mice compared with controls, indicating increased mucosal protection and regeneration. Conclusions—The significantly reduced susceptibility of mice overexpressing TGF-AE to DSS further substantiates that endogenous TGF-AE is a pivotal mediator of protection and/or healing mechanisms in the colon. (Gut 1998;43:64‐70)