大鼠肝移植后的排斥反应与吲哚胺2,3双加氧酶基因的关系

The relationship of indoleamine 2,3-dioxygenase gene expression and acute immune rejection after rat(liver) transplantation

目的检测吲哚胺2,3双加氧酶(IDO)基因在大鼠肝移植后移植肝中的表达情况,探讨其与急性排斥反应的关系。方法先行大鼠原位肝移植,一组供、受者均为近交系SD大鼠(近交系移植组),另一组为同种移植组,SD大鼠接受Wistar大鼠供肝移植。分别于术后第2、5、7、14d处死受者,取出移植肝,采用逆转录聚合酶链反应(RT-PCR)、Western印迹法及免疫组化法,检测移植肝组织中IDO mRNA表达I、DO蛋白的水平以及IDO在移植肝细胞中的表达。结果近交系移植组IDO mRNA的表达高峰出现在术后第5d,至第14d基本无表达;同种移植组IDO mRNA的表达明显增强,高峰出现在第7d,持续2周以上。两个组移植肝组织中IDO蛋白的表达与各自的IDOmRNA变化相一致。术后第5、7、14d,同种移植组IDO阳性细胞的比例明显高于近交系移植组(P<0.01),强阳性染色主要见于汇管区单个核细胞,以胞浆内染色为主。结论急性排斥反应时IDO基因表达明显增强,IDO的表达水平与急性排斥反应的严重程度一致。

Objective To detect the expression of indoleamine 2,3-dioxygenase （IDO） gene in the rat liver grafts after liver transplantation, and discuss the relationship between IDO gene expression and posttransplantation immune reiection. Methods Orthotopic liver transplantations （OLTx） were performed in SD rats at first. One group was inbred line OLTx group transplanted with SD rats donor grafts, and the other group was allogenic OLTx group transplanted with Wistar rats donor grafts. Animals were sacrificed on the day 2, 5, 7, 14, and liver grafts were collected for measuring the expression of IDO mRNA, IDO protein and IDO positive cells in the grafts by using of RT-PCR,Western-blot and anti-IDO monoclonal antibody immunochemistry methods respectively. Results The peak expression of IDO mRNA occurred on the day 5, and almost no expression till day 14 in inbred line group. In comparison to the inbred group, IDO mRNA expression was increased obviously in the allogenic group and the peak expression occurred on the day 7, and high level kept for over 2 weeks. The expression of IDO protein in each group was correspondent to its own mRNA expression respectively. The ratio of IDO positive cells in the allogenic group was much higher than that in the inbred group on the postoperative day 5, 7, 14 （P〈0. 01 ）. The positive staining with anti-IDO anti-body was mainly seen in the cytoplasm of monocytes infiltrating in the portal area. Conclusion There is a significant overexpressed IDO in the liver grafts during the acute rejectiorL The intensity of IDO gene expression is associated with the severity of acute immune rejection.