重组pEGFP-N1-H2Bl质粒载体诱导心脏移植免疫耐受

目的 探讨H2-Bl基因诱导小鼠心脏移植免疫耐受的机制和效果.方法 建立小鼠颈部心脏异位移植模型,供体心脏经主动脉根部灌注H2-Bl质粒真核表达载体后进行心脏移植.实验分4组:对照组、环孢素A(CsA)组、H2-Bl质粒转染组、H2-Bl质粒转染+CsA组.各组于术后1、3和7天各动态枪测供心病理改变,免疫组织化学方法测供心CD40表达情况,流式细胞仪检测供心血清中Th1/Th2细胞因子变化,记录移植心脏存活时间.结果 对照组移植后排斥反应最重,其余组与之比较均有所减轻,以H2-Bl质粒转染+CsA组排斥反应最轻.免疫组化显示术后7天时H2-Bl质粒转染组CD40与对照组相比差异有统计学意义(P＜0.05),CsA组、H2-Bl+CsA组CD40与对照组相比差异有统计学意义(P＜0.01).H2-Bl+CsA组Th2细胞因子表达较其余组增加而Th1细胞因子则减少,到术后7天时各组Th细胞因子与对照组相比差异均有统计学意义(P＜0.05).与对照组相比,其余各组小鼠供心存活天数均延长(P＜0.05).结论 H2-Bl基因干预可一定程度诱导移植心脏免疫耐受,延长同种异体小鼠颈部移植心脏存活时间.

Immune tolerance induced by H2-Bl plasmid vectors for heterotopic heart transplantation in mice

Objective Cervical heterotopic heart transplantation model was established in different inbred strains of mice with modified cuff technique. Inbred male Balb/c mice and C57BL/6 mice were selected as donors and recipients, respectively. Mice were randomly assigned into four groups: control group (the donor hearts were perfused through coronary artery with 200 μl, 0℃～4℃ St. Thomas Ⅱ solution during 2 to 3 min, then they were immersed in it for 15 min), CsA group ( the donor hearts were perfused with the same method as for the control's and intraperitoneal injection of CsA 5 mg· g-1 · d -1 was given after surgery ), H2-B1 transfection group (the donor hearts were perfused through coronary artery with 200 μl, 0℃ -4℃ St. Thomas Ⅱ solution contained with 30 μg H2-Bl plasmid vectors during 2 to 3 min, then they were immersed in it for 15 min ), and H2-B1 + CsA group ( the donor hearts were perfused with St. Thomas Ⅱ solution contained H2-Bl gene plasmid and intraperitoneal injection of CsA was given after surgery as mentioned above. ). At 1,3 and 7 days after transplantation, three allografts were harvested at each time points in all of the groups, respectively, for pathological examination and analysis of CD40 expression with immunohistochemistry assays. The expression of Th1/Th2 cytokines were also determined with flow cytometry. The survival time of rest allografts were observed. Results Histological features for rejection were observed more apparent in the grafts of control group than those in other groups, especially those in H2-Bl + CsA group. The expression of CD40 in H2-Bl + CsA group and CsA group was lower significantly than that of the control group ( P ＜0.01 ), so was the expression of CD40 in the H2-Bl group as compare with that of the control group (P ＜0.05). No significant difference between H2-Bl group and CsA group (P ＞0.05 ) at 7 days was observed. The expression of IL-2, TNF-α (Th1 cytokines) in control group was much higher than that in other groups, and the expression of IL-4 ( Th2 cytokine) in control group was much lower ( P ＜0.05 ). The level of IL-4 in CsA group increased significantly at 3 days ( P ＜ 0.05 ), with a peak level at 7 days after transplantation (P＜0.01). The survival time of grafts was significantly prolonged in CsA group (P＜0.01), H2-Bl group (P＜0.05) and H2-Bl+CsA group(P＜0.01). Conclusion Treating the donor hearts with H2-Bl plasmid vectors at the time of transplantation may suppress rejection in the heart allografts and prolong the survival time through some presumed mechanisms such as preventing upregulation of CD40 expression, relucing the production of IL-2 and TNF-α, increasing the production of IL-4, and as a result, inducing immune tolerance, as well as improving the function of transplanted heart grafts.