PD-L1Ig对大鼠肝移植免疫耐受影响的实验研究

The Study of the Immune Tolerance Induced by PD-L1Ig in Rat Liver Transplantation

目的探讨PD-L1Ig对诱导大鼠肝移植免疫耐受的影响.方法采用雄性大鼠构建Wistar→SD大鼠肝移植模型20例后,将大鼠随机分为两组:空白对照组和PD-L1Ig组,每组数量为10只,其中空白对照组不给予任何药物,PD-L1Ig组给予PD-L1Ig腹腔内注射,分别在手术当天、第2天、第4天及第6天重复给予腹腔内注射,术后观察动物生存情况、精神、食欲,术后1周处死部分动物取肝脏及血标本.血清酶学检测血肝功、流式细胞仪检测CD4+CD25+Treg比例分析,肝脏病理检测排斥反应情况.结果血清肝功能测定谷丙转氨酶、谷草转氨酶及总胆红素指标,PD-L1Ig腹腔内注射组要低于对照组(P<0.05);肝脏病理检测发现空白对照组大鼠肝脏汇管区大量单核细胞积聚,并波及汇管周正常肝细胞,注射PD-L1Ig组大鼠肝脏汇管区炎症则相对较轻,只有少量炎症细胞积聚,参照Baff评分标准,肝脏排斥反应注射PD-L1Ig组为中度,空白对照组为重度;流式分析CD4+CD25+Treg比例显示,PD-L1Ig组外周血中CD4+CD25+Treg细胞的比例较对照组高(P<0.05).结论 PD-L1lg提高大鼠受损的肝功能,可减轻肝移大鼠肝损伤程度;可引起肝移植后大鼠外周血中CD4+CD25+Treg比例升高,具有诱导肝移植免疫耐受作用.

Objective To explore the effect of PD-L1Ig on the immune tolerance in rats with liver transplantation.Methods Twenty ROLT models were established by Kamada two-cuff technique,with inbred male Wistar rats and male SD rats served as donor and recipient respectively.The recipients were randomly devided into 2 groups according to different treatments:no treatment A(Wistar→SD n=10)and B treated with PD-L1Ig(Wistar→SD n=10)after the day of operation,the following day,the fourth day and sixth day.The clinical characters,the animal survival,mental and appetite were observed.The liver and blood samples were taken form rats after one week for detecting liver function and proportions of CD4+CD25+Treg and observing the rejection of liver pathology.Results In the treatment group,the liver function test,including serum alanine aminotransferase,aspartate aminotransferase and total bilirubin,was superior to control group(P < 0.05).Pathology of liver revealed there were a large number of mononuclear cells around the portal tract area in blank control group.The inflammation of PD-L1Ig group was relatively less serious,only a little accumulation of inflammatory cells.The liver rejection of blank control was more serious than PD-L1Ig group.Referencing Baff marking,the rejection was moderate and severe in group of PD-L1Ig and blank control,respectively.The group of PD-L1Ig showed a lower immune response and lighter rejection of liver than the control group.Flow cytometry analysis of CD4+ CD25+ Treg showed that the proportion of peripheral blood CD4+CD25+Treg cells in PD-L1Ig group was significantly higher than control group(P<0.05).Therefore,PD-L1Ig group rats showed better negative regulator activity of immune cell.Conclusions The liver functions of PD-L1Ig treated rats are better.A low immune response can be induced in the rats of ROLT by PD-L1Ig treatment.The proportion of peripheral blood CD4+CD25+Treg increases after liver transplantation in rats,which might be a mechanism of immune tolerance.