Kumano Kenjiro, Nishinakamura Hitomi, Mera Toshiyuki, Itoh Takeshi, Takahashi Hiroyuki, Fujiwara Toshiyoshi, Kodama Shohta
a Department of Regenerative Medicine and Transplantation , Faculty of Medicine, Fukuoka University , Fukuoka , Japan.
b Department of Gastroenterological Surgery , Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences , Okayama , Japan.
Islets. 2016 Sep 2;8(5):145-55. doi: 10.1080/19382014.2016.1223579.
Although current immunosuppression protocols improve the efficacy of clinical allogenic islet transplantation, T cell-mediated allorejection remains unresolved, and major histocompatibility complexes (MHCs) play a crucial role in this process. Papain, a cysteine protease, has the unique ability to cleave the extracellular domain of the MHC class I structure. We hypothesized that pretreatment of donor islets with papain would diminish the expression of MHC class I on islets, reducing allograft immunogenicity and contributing to prolongation of islet allograft survival. BALB/c islets pretreated with papain were transplanted into C57BL/6J mice as an acute allorejection model. Treatment with 1 mg/mL papain significantly prolonged islet allograft survival. In vitro, to determine the inhibitory effect on T cell-mediated alloreactions, we performed lymphocyte proliferation assays and mixed lymphocyte reactions. Host T cell activation against allogenic islet cells was remarkably suppressed by pretreatment of donor islet cells with 10 mg/mL papain. Flow cytometric analysis was also performed to investigate the effect of papain treatment on the expression of MHC class I on islets. One or 10 mg/mL papain treatment reduced MHC class I expression on the islet cell surface. Pretreatment of donor islets with papain suppresses MHC class I-mediated allograft rejection in mice and contributes to prolongation of islet allograft survival without administration of systemic immunosuppressants. These results suggest that pretreatment of human donor islets with papain may reduce the immunogenicity of the donor islets and minimize the dosage of systemic immunosuppressants required in a clinical setting.
尽管当前的免疫抑制方案提高了临床同种异体胰岛移植的疗效，但T细胞介导的同种异体排斥反应仍未得到解决，主要组织相容性复合体（MHC）在这一过程中起着关键作用。木瓜蛋白酶是一种半胱氨酸蛋白酶，具有切割MHC I类结构胞外域的独特能力。我们假设用木瓜蛋白酶预处理供体胰岛会减少胰岛上MHC I类分子的表达，降低移植物的免疫原性，并有助于延长胰岛移植的存活时间。将用木瓜蛋白酶预处理的BALB/c胰岛作为急性同种异体排斥模型移植到C57BL/6J小鼠体内。用1mg/mL木瓜蛋白酶处理可显著延长胰岛移植的存活时间。在体外，为了确定对T细胞介导的同种异体反应的抑制作用，我们进行了淋巴细胞增殖试验和混合淋巴细胞反应。用10mg/mL木瓜蛋白酶预处理供体胰岛细胞可显著抑制宿主T细胞对同种异体胰岛细胞的激活。还进行了流式细胞术分析，以研究木瓜蛋白酶处理对胰岛上MHC I类分子表达的影响。1或10mg/mL木瓜蛋白酶处理可降低胰岛细胞表面MHC I类分子的表达。用木瓜蛋白酶预处理供体胰岛可抑制小鼠体内MHC I类分子介导的移植物排斥反应，并有助于延长胰岛移植的存活时间，而无需使用全身性免疫抑制剂。这些结果表明，用木瓜蛋白酶预处理人供体胰岛可能会降低供体胰岛的免疫原性，并在临床环境中尽量减少所需全身性免疫抑制剂的剂量。
