2,4,6-trinitrobenzene sulfonic acid-induced chronic colitis with fibrosis and modulation of TGF-β1 signaling

AIM:To investigate whether targeting proteasome might reverse intestinal fibrosis in rats.METHODS:Chronic colitis was induced in rats by repeated administration of increasing dose of2,4,6-trinitrobenzene sulfonic acid(TNBS,15,30,45,60,60,60 mg)by rectal injection for 6 wk(from day0 to day 35),while control rats received the vehicle.TNBS+bortezomib(BTZ)rats received intraperitoneal injections of BTZ twice weekly(from day 37 to day44)at a dose of 25 mg/kg,whereas the control and TNBS groups received the same amount of the vehicle.Histologic scoring of inflammation and fibrosis was performed.Colonic production of transforming growth factor(TGF)-βwas measured by ELISA.Colon fibrosisrelated proteins such as phospho-p38,phosphoSMAD2/3,Akt and peroxisome proliferator activated receptorγ(PPARγ)were studied by western blot.Expression of the tight junction proteins,occludin and claudin-1,were assessed by Western blot.Colon proteasome activities(chymotrypsin-like and trypsinlike activities)were assessed.RESULTS:TNBS-treated rats had a higher colon weight/length ratio compared to control rats(P 0.05).In contrast,bortezomib had no effect on other studied parameters such as fibrosis score,TGF-βsignaling,or tight junction expression(P>0.05 for all).CONCLUSION:Rats wi