PDL_1Ig基因修饰的骨髓间充质干细胞诱导大鼠肝移植免疫耐受

目的:探讨程序性死亡因子配体1免疫球蛋白(PDL_1Ig)基因转染骨髓间充质干细胞(BMSCs)抑制大鼠原位肝移植免疫排斥反应的机制。方法:培养并鉴定大鼠的BMSCs,重组腺病毒p Ad Easy-1/PDL_1Ig感染BMSCs 72 h后,提取细胞总蛋白,采用Western blot法检测转染后BMSCs中PDL_1Ig的蛋白表达。混合淋巴细胞反应检测未转染和转染后的BMSCs对外周血T淋巴细胞活力的抑制作用。以雄性Wistar大鼠为供体,以雄性SD大鼠为受体,采用改良的两袖套法进行原位肝移植,建立大鼠原位肝移植急性排斥反应模型。随机分为对照组、BMSCs治疗组、空载体BMSCs治疗组(BMSCs/GFP)和转基因治疗组(BMSCs/PDL_1Ig),每组10对。每组随机取5只于术后第7天处死,检测外周血白细胞介素(IL)-2、IL-4和干扰素γ(IFN-γ)水平,检测肝功能情况,光学显微镜下观察移植肝的病理学变化,另外5只观察生存情况及时间。结果:重组p Ad Easy-1/PDL_1Ig感染BMSCs 72 h后,BMSCs中有PDL_1Ig的蛋白表达。BMSCs/PDL_1Ig抑制淋巴细胞活力的作用强于BMSCs/GFP。BMSCs/PDL_1Ig组的IL-4水平明显高于其它3组,IL-2和IFN-γ水平也明显降低(P0.05)。各实验组移植后7 d检测肝功能,发现BMSCs/PDL_1Ig组的肝功能改善最明显,ALT、AST和TBil基本达到正常水平,与对照组比较差异有统计学显著性,与BMSCs治疗组和空载体BMSCs治疗组比较差异也有统计学显著性。肝组织病理检查结果显示对照组移植肝发生了重度排斥反应,BMSCs治疗组和空载体BMSCs治疗组移植肝亦发生排斥反应,但与对照组比较程度较轻,BMSCs/PDL_1Ig组移植肝几乎没有排斥反应,受体存活时间大部分超过100 d,显著长于其它3组(P0.05)。结论:PDL_1Ig修饰的BMSCs可抑制大鼠肝移植排斥反应,诱导肝移植免疫耐受,其效果优于BMSCs单用。

PDL1Ig gene-modified BMSCs induce immune tolerance in rat liver transplantation

AIM: To investigate the effects of bone marrow mesenchymal stem cells(BMSCs) modified by programed death ligand-1 immunoglobulin(PDL₁Ig) gene on immune rejection of orthotopic liver transplantation in rats. METHODS: Rat BMSCs were cultured and identified. The protein expression of PDL₁Ig in the BMSCs 72 h after infection with pAdEasy-1/PDL₁Ig was detected by Western blot. Mixed lymphocyte reaction was used to detect the inhibitory effect of BMSCs on the viability of T-lymphocytes in peripheral blood. The male Wistar rats were used as donors(n=40), and the male SD rats were used as recipients(n=40). The rat model of orthotopic liver transplantation was established by improved cuff method for observing acute rejection. The rats were randomly divided into control group, BMSCs treatment group, BMSCs/GFP treatment group and BMSCs/PDL₁Ig treatment group with 10 pairs each. Five rats were executed at the 7th day and the remains were used for measuring the survival time. RESULTS: The expression of PDL₁Ig in the BMSCs was detected after pAdEasy-1/PDL₁Ig infection. The effect of BMSCs/PDL₁Ig on the viability of the lymphocytes was stronger than that of BMSCs/GFP. The level of IL-4 in BMSCs/PDL₁Ig group was significantly higher than that in the other 3 groups, while the levels of IFN-γ and IL-2 were significantly decreased. The liver function in BMSCs/PDL₁Ig group was significantly improved and the levels of ALT, AST and TBil were almost recovered to normal at the 7th day after transplantation. Severe rejection reaction was observed in control group, and rejection reactions were decreased with different degrees in BMSCs treatment group and BMSCs/GFP treatment group. Much slighter rejection reaction and significantly longer survival time were showed in BMSCs/PDL₁Ig group than those in the other 3 groups. CONCLUSION: PDL₁Ig-modified BMSCs inhibit the rejection of liver transplantation in rats and induce the immune tolerance, and the effect is better than that of BMSCs alone.