Shieh Shing-Jia, Chou Feng-Cheng, Yu Pei-Ning, Lin Wen-Chi, Chang Deh-Ming, Roffler Steve R, Sytwu Huey-Kang
Graduate Institute of Life Sciences.
J Immunol. 2009 Aug 15;183(4):2277-85. doi: 10.4049/jimmunol.0900679. Epub 2009 Jul 27.
T cell-mediated immunodestruction of pancreatic beta cells is the key process responsible for both the development of autoimmune diabetes and the induction of rejection during islet transplantation. In this study, we investigate the hypothesis that transgenic expression of an agonistic, membrane-bound single-chain anti-CTLA-4 Fv (anti-CTLA-4 scFv) on pancreatic beta cells can inhibit autoimmune processes by selectively targeting CTLA-4 on pathogenic T cells. Strikingly, transgenic expression of anti-CTLA-4 scFv on pancreatic beta cells significantly protected NOD mice from spontaneous autoimmune diabetes. Interestingly, local expression of this CTLA-4 agonist did not alter the diabetogenic properties of systemic lymphocytes, because splenocytes from transgenic mice or their nontransgenic littermates equally transferred diabetes in NOD/SCID recipients. By analyzing the T cell development in anti-CTLA-4 scFv/Th1/Th2 triple transgenic mice, we found that beta cell-specific expression of CTLA-4 agonist did not affect the development of Th1/Th2 or CD4(+)CD25(+) regulatory T cells. Most strikingly, islets from transgenic mice inhibited T cell response to immobilized anti-CD3 in a T cell-islet coculture system, suggesting a trans-mediated inhibition provided by transgenic islets. Finally, transgenic islets implanted in diabetic recipients survived much longer than did wild-type islets, indicating a therapeutic potential of this genetically modified islet graft in autoimmune diabetes.
T细胞介导的胰腺β细胞免疫破坏是自身免疫性糖尿病发生发展以及胰岛移植排斥反应诱导过程中的关键环节。在本研究中，我们探究了一个假说，即在胰腺β细胞上转基因表达一种具有激动作用的膜结合型单链抗CTLA-4 Fv（抗CTLA-4 scFv），可通过选择性靶向致病性T细胞上的CTLA-4来抑制自身免疫过程。令人惊讶的是，在胰腺β细胞上转基因表达抗CTLA-4 scFv可显著保护非肥胖糖尿病（NOD）小鼠免受自发性自身免疫性糖尿病的侵害。有趣的是，这种CTLA-4激动剂的局部表达并未改变全身淋巴细胞的致糖尿病特性，因为来自转基因小鼠或其非转基因同窝小鼠的脾细胞在NOD/SCID受体中同等程度地转移了糖尿病。通过分析抗CTLA-4 scFv/Th1/Th2三转基因小鼠中的T细胞发育情况，我们发现CTLA-4激动剂的β细胞特异性表达并不影响Th1/Th2或CD4(+)CD25(+)调节性T细胞的发育。最引人注目的是，在T细胞-胰岛共培养系统中，转基因小鼠的胰岛抑制了T细胞对固定化抗CD3的反应，这表明转基因胰岛提供了一种反式介导的抑制作用。最后，植入糖尿病受体的转基因胰岛存活时间比野生型胰岛长得多，这表明这种基因修饰的胰岛移植物在自身免疫性糖尿病中具有治疗潜力。
