ICOS-Ig 融合蛋白联合亚剂量环孢素A诱导小鼠移植心脏长期存活

目的 探讨可诱导共刺激分子-Ig融合蛋白(ICOS-Ig)联合亚剂量环孢素A(CsA)对小鼠移植心脏存活时间的影响及其机制.方法 自行构建ICOS-Ig.以Balb/c小鼠为供者,C57BL/6小鼠为受者,套管法制备小鼠颈部心脏移植模型,然后将模型分为5组:(1)未处理组,不做任何处理;(2)对照IgG组,移植当天以及术后第2、4、6天腹腔注射IgG 250 μg;(3)IcoS-Ig组,移植当天以及术后第2、4、6天腹腔注ICOSIg250 μg;(4)CsA组,移植当天以及术后第1～7天腹腔注射CsA 10mg/kg;(5)ICOS-Ig+CsA组,同时给予ICOS-Ig和CsA,使用时间和剂量同前.术后观察移植心脏存活时间,观察移植后第7天移植心脏的病理变化,并进行供、受者混合淋巴细胞反应(MLR),测定受者血清中供者特异性的同种抗体水平.结果 各组小鼠移植心脏存活时间分别为:未处理组(8.5±1.5)d,对照IgG(8.00.8)d,ICOSIg(29.57.7)d.CsA处理组(21.0±5.0)d,ICOS-Ig+CsA组移植心脏存活时间均超过50d,6只(6/9)移植心脏存活时间>100d,ICOS-Ig+CsA组与其他4组比较,差异均有统计学意义(P<0.01).移植后7d,未处理组及对照IgG组心肌明显变性,纤维断裂,间质水肿,肌束间及血管周围有大量炎症细胞浸润,而ICOS-Ig组和CsA组心肌无明显变性,间质略水肿,血管周围有少量淋巴细胞浸润,ICOS-Ig+CsA组的病理改变明显I(X)S-Ig组和CsA组.移植后7d,ICOS-Ig组和CsA组的脾脏淋巴细胞对同种抗原刺激反应比未处理组和对照IgG组明显降低(P<0.05),而ICOS-Ig+CsA组的抑制作用明显强于ICOS-Ig组和CsA组(P<0.05).移植后7d,ICOS-Ig组和CsA组受者血清中针对特异性供者的抗体水平明显低于未处理组和对照IgG组(P<0.05),ICOS-Ig+CsA组的抗体水平明显低于ICOS-Ig组和CsA组(P<0.05).结论 ICOS-Ig可以降低受者对供免疫反应性,延长移植心脏的存活时间,联合亚剂量CsA可使异体移植心脏长期存活.

ICOS-Ig combined with subclinical dose of CsA induces long term survival of mouse cardiac allografts

Objective To investigate the potential role of IC0s-Ig and CsA in inducing transplantation tolerance and the mechanisms thereof. Methods ICOS-Ig was a fusion protein of human ICOS extracellular region and IgG Fc fragment.Cardiac allograft from BALB/c mouse was transplanted to C57BL/6 mouse Animals were randomly divided into 5 groups:(1) un-treated group;(2)IgG-treated group,250g,i.p.day 2,4,6;(3)ICOS Ig-treated group,250g,i.P.day 2,4,6;(4) CsA-treated group,10 mg/kg,i.p.day 0-6;(5)ICOS-Ig+CsA-treated group.The survival time and pathological changes of the cardiac allografts were monitored.The mixed lymphoeyte reaction (MLR) and the alloantibody level of the recipients were also detected.Results The median survival time (MST) of the cardiac allografts was (8.5±1.5) days in un-treated group,(8.0±0.8) days in IgG-treated group,(29.5±7.7) days in ICOS-Ig-treated group,and(21.0±5.0) days in CsA-treated group.respectively.In ICOS-Ig + CsA-treated group,the MST was prolonged to longer than 100 days,which was significantly longer than other four groups(P<0.01).Allogeneic hearts from ICOS-Ig and/or CsA immunized recipients revealeel milder histological changes than control groups(P<0.05).Mechanical ahalysis revealed that splenic T cells from recipients also exhibited depressed MLR activities.The alloantibody level in ICOS-Ig-treated group and/or CsA-treated group was lower than in control groups(P<0.05),suggesting ICOS-Ig not only inhibited cell immunity,but also depressed humoral response.Conclusion ICOS-Ig combined with CsA leads to a long-term survival of mouse cardiac allografts.The induced tolerance is donor-specific and the mechanisms may be associated with T cell anergy.