摘要：AIM: Ulinastatin has been reported to be beneficial for maintenance of steroid-refractory inflammatory bowel disease (IBD), but the mechanism underlying remains uncertain. Leukocyte recruitment to inflammatory site plays an important role in the pathogenesis of IBD, analysis of leukocyte and endothelium interaction may provide new avenues for treatment of IBD. In this study, we evaluated the efficacy of Ulinastatin in dextran sulfate sodium (DSS) induced colitis rat model using intravital video microscopy. METHODS: Rats were given drinking water containing 3.5% (W/V) DSS for 10 days then 1% for 14 days. DSS induced colitis rats were treated Ulinastatin 3 000 unit*kg-1*d-1 via intraperitoneum during 1% DSS feeding. Controls received distilled water for 24 days. Body weight was determined for all groups. Colitis severity was assessed using histological scoring systems by H&E sections. Intravital microscopic techniques were used to quantitate leukocyte adhesion (LA), leukocyte emigration (LE) and venular protein leakage (VPL) in rat mesentery. RESULTS: DSS induced loss of body weight, whereas Ulinastatin-treated rat showed a significant increase in body weight. Histological analysis revealed improvement of colitis such as leukocyte infiltration, loss of goblet cells, transmural edema. DSS intake elicited increase in LA, LE, and VPL compared to control group. Ulinstatin significantly reversed the increase in LA, LE, and VPL induced by DSS. CONCLUSION: Administration of Ulinastatin effectively ameliorates experimental colitis by interfering with leukocyte recruitment, and may become a potential candidate for control of inflammation of IBD.