The Protective Role Of GM6001 On TNBs-induced Ulcerative Colitis In Rats

Background and Objective:Ulcerative Colitis (UC) predominantly invades mucosa and submucosa of colon. It is characterized by degradation of extracellular matrix (ECM) and mucosal ulceration. Previous studies show that matrix metalloproteinases (MMPs) play a major role in this process. Increased expression of MMP-1 and comparatively deficient expression of TIMP-1 are significantly related to tissue damage in ulcerative colitis. MMP-1 and TIMP-1 could be used as biomarkers to judge the severity of clinical symptoms in patients with ulcerative colitis. The activities of MMPs can be inhibited by tissue inhibitors of matrix metalloproteinases (TIMPs), therefore, substitute treatment using exogenous MMPs inhibitor(MMPI)might be a new way in treating ulcerative colitis.This study was aimed to examine the expression of MMP-1 and TIMP-1 at both mRNA and protein levels and to evaluate the protective role of exogenous MMPI, GM6001(1Ilomastat), on TNBs (trinitrobenzenesulfonic acid)-induced ulcerative colitis in rats so that new method could be used potentially in the treatment of UC in the future.Methods:Male SD rats were randomly divided into four groups of eight animals each. Ulcerative colitis was induced by introcolonic adminstration of TNBs. In TNBs treated group, the animals received only introcolonic TNBs; in the two protective groups the animals received TNBs+10mg/kg GM6001(protective group A), and TNBs+20mg/kg GM6001(protective group B) intraperitoneally. GM6001 was administered 30 min before induction of colitis and subsequently twice daily. Eight rats received only introcolonic 0.9% saline as controls. Animals were killed after 3 weeks, and segments of colon were obtained. RT-PCR and immunohistochemistrywere used to examine the expression of MMP-1 and TIMP-1 at both mRNA and protein levels, and Hematoxylin-Eosin(HE)staining was used for pathological study.Results:1. Pathological results with HE stainingThe model of ulcerative colitis was successfully induced by introcolonic TNBs. Mucosa defects, penetrating into submucosa area could be seen with infiltrations of inflammatory cells, mainly neutrophils and lymphocytes. Tissue damage could also be clearly observed. Comparison between the protective groups and UC model group showed that the severity of inflammation was greatly decreased in the former ones, i.e. in both 10mg/kg and 20 mg/kg groups. The inflammatory cells including neutrophils and leukomonocytes in the colonic mucosa were decreased obviously. It was also found that the severity of mucosa damage in the protective group B was improved to a greater extent when compared with protective group B. Proliferation of blood vessles, regeneration of epithielia covering the ulcer surface and granulation tissues could all be observed in protective group B.2.Expression of MMP-1 and TIMP-1 by RT-PCR and by imunohistochemistry(1) The expression of MMP-1 and TIMP-1 in TNBs-treated group and GM6001 protective group was significantly higher than that of controls( P<0.05 ) with the increase of MMP-1 being more profound. The expression of MMP-1 in TNBs-treated group was significantly higher than in GM6001 protective groups(P<0.05); The expression of TIMP-1 showed no significant difference between GM6001 protective groups and TNBs-treated group(P>0.05).(2) The expression of MMP-1 in GM6001 protective group A was higher than that in GM6001 protective group B(P<0.05); but the expression of TIMP-1 has no significant difference between these two group(sP>0.05). Conclusions:1. Expression of MMP-1 and TIMP-1 is significantly increased in rats with ulcerative colitis induced by TNBs, with MMP-1 being more profound. So MMP-1 and TIMP-1 may play an important role in the development of UC.2. GM6001 can improve injuries of colonic mucosa induced by TNBs with a mechnisim of inhibition of MMP-1 activity and in a dose–dependentpattern. Therefore, GM6001 has a protecrive role on TNBs-induced ulcerative colitis in rats and could be used clinically in treating UC with a great potential in the future.