Porcine PD-L1: cloning, characterization, and implications during xenotransplantation
Porcine PD-L1: cloning, characterization, and implications during xenotransplantation
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DOI：
10.1111/j.1399-3089.2007.00403.x
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发表时间：
2007-05-01
影响因子：
3.9
通讯作者：
Lee, Gene
中科院分区：
文献类型：
--
作者：
Jeon, Dae-Hyun;Oh, Keunhee;Lee, Gene
背景资料：通过操纵细胞介导的异种免疫应答实现的有效干预将极大地增加异种移植的临床可行性，因为通过供体器官的遗传调节，立即的超急性排斥反应变得可控。内源性负调控信号如程序性死亡1（PD-1）-程序性死亡配体1（PD-L1）系统是控制细胞介导的异种免疫应答的候选靶点。使用猪PD-L1转染的旁观者细胞测试克隆猪PD-L1对人CD 4（+）T细胞活化的功能效应。结果：猪PD-L1（GenBank登录号AY 837780）与人PD-L1的同源性为73.8%，其胞外区含有两个免疫球蛋白结构域。此外，在中国仓鼠卵巢（CHO）细胞上表达的猪PD-L1可抑制仅抗CD 3或抗CD 3+抗CD 28刺激的人CD 4（+）T细胞增殖。在猪PD-L1/CHO细胞的存在下，凋亡活化的人T细胞的存活率增加了30%以上，并且在人T细胞活化过程中加入重组人PD-1-Fc融合蛋白逆转了猪PD-L1的抑制作用。结论：克隆的猪PD-L1与人PD-L1具有高度的序列同源性，分子结构相似。此外，猪PD-L1以人PD-1依赖性方式抑制人CD 4（+）T细胞活化，这涉及活化的T细胞凋亡。作者认为，PD-1-PD-L1可能在异种移植过程中发挥重要的内源性免疫调节作用，该系统的有效应用将提高异种移植器官的存活率。
Background: Effective intervention achieved by manipulating cell-mediated xenogeneic immune responses would critically increase the clinical feasibility of xenotransplantation as immediate hyperacute rejections become controllable through genetic modulations of donor organs. Endogenous negative regulatory signals like the programmed death 1 (PD-1)-programmed death ligand 1 (PD-L1) system are candidate targets for the control of cell-mediated xenogeneic immune response.Methods: A porcine PD-L1 molecule was cloned using RACE (rapid amplification of cDNA ends) technology based on the human PD-L1 sequence. The functional effects of cloned porcine PD-L1 were tested on human CD4(+) T cell activation using porcine PD-L1-transfected bystander cells. Cellular proliferation was monitored by [H-3] thymidine incorporation, and human T cell apoptosis was measured by flow cytometry.Results: Porcine PD-L1 (GenBank accession number AY837780) was found to have 73.8% sequence homology with human PD-L1 and to contain two immunoglobulin domains in its extracellular region. Moreover, porcine PD-L1 expressed on Chinese hamster ovary (CHO) cells inhibited human CD4(+) T cell proliferation stimulated with anti-CD3 only or anti-CD3 plus anti-CD28. Percentages of apoptotic activated human T cells increased by over 30% in the presence of porcine PD-L1/CHO cells, and the addition of recombinant human PD-1-Fc fusion proteins during human T cell activation reversed the inhibitory effects of porcine PD-L1.Conclusions: Cloned porcine PD-L1 showed high sequence homology with human PD-L1 and a similar molecular structure. Moreover, porcine PD-L1 inhibited human CD4(+) T cell activation in human PD-1-dependent manner, and this involved activated T cell apoptosis. The authors suggest that PD-1-PD-L1 might play an important endogenous immune regulatory role during xenogeneic transplantation, and that the effective application of this system would improve transplanted xenogeneic organ survival.