Ulinastatin Ameliorates Pancreatic Tissue Damage Of Severe Acute Pancreatitis Through Modulating Regulatory T Cells

Objective Ulinastatin or urinary trypsin inhibitor(UTI)has been shown to effectively prevent the inflammatory response and reduce mortality caused by severe acute pancreatitis(SAP).However,the mechanism for its action remains unclear.We have investigated the effect and the related mechanism of ulinastatin on regulatory T-cells(Tregs).Methods 1.Total of 100 rats were used in the study.Fifty rats were divided into 5 groups according to the animal model and treatment: control group,SAP group,SAP with ulinastatin(5000 U/kg),SAP with ulinastatin(10000 U/kg),SAP with ulinastatin(30000 U/kg).In ulinastatin treatment groups,SAP-induced animals were administered with 1ml ulinastatin through intraperitoneal injection at 0 h,6 h and 12 h.We studied the effects of ulinastatin on the dynamic changes of CD4+CD25+ Tregs,CTLA-4,certain nuclear transcription factor,inflammatory response,and the pathological structure in the SAP rats.The other 50 rats,also divided into 5 groups as above,were used to evaluate the effect of ulinastatin on the mortality rate after SAP operation,respectively.2.Between October 2014 to August 2016,127 patients with AP including three types of severity(MAP,MSAP,SAP)admitted to the Affiliated Union Hospital of Fujian Medical University consecutively were divided into two groups(the UTI group and control group)according to the method of stratified randomization.All of the patients received the conventional therapy of AP.In addition,UTI was added to the patients in UTI groups.We collected peripheral blood on the first day of admission before treatment and the third and seventh days during treatment.Treg were measured by flow cytometry,and the levels of IL-10 were detected by enzyme-1inked immunosorbent assay(ELISA).Results1.We showed that the tissue damages of pancreas were significantly reduced in ulinastatin treated SAP rats.We also showed that the frequencies of CD4+ T cells and Tregs,as well as the expressions of TGF-?1,CTLA-4,and Foxp3 were decreased in the SAP animals while IL-1?,IL-10 and TNF-? were significantly increased.Moreover,treatment with ulinastatin up-regulated the proportion of Tregs in CD4+ T cells and the expression of IL-10,Foxp3 and CTLA-4 in the SAP rats in a dose dependence fashion,but down-regulated the levels of L-1? and TNF-?,myeloperoxidase(MPO)activity.2.On the third and seventh days,the percentage of Treg in UTI groups of the three types was higher than that of control groups and P<0.05.For patients with MAP,the levels of IL-10 in UTI group were higher than control group only on the third day.For patients with MSAP and SAP,the levels of IL-10 in UTI groups were higher than control groups both on the third and seventh(P<0.05).The effective ratio of the treatment in UTI groups were higher than control groups.Conclusions Ulinastatin regulated the immune function and alleviates the inflammatory response during the patients or rats with AP by inducing the expansion of Treg cells,and its mechanism may be connected with improving the level of IL-10.