Wilhelm Maud, Kaur Amandeep, Geng Anne, Wernli Marion, Hirsch Hans H
Transplantation and Clinical Virology, Department of Biomedicine, University of Basel, Basel, Switzerland.
Transplantation. 2025 Sep 1;109(9):1526-1539. doi: 10.1097/TP.0000000000005399. Epub 2025 Apr 9.
BK polyomavirus (BKPyV) nephropathy is a major cause of premature kidney transplant failure. Current management relies on reducing immunosuppression to restore BKPyV-specific immune control. Ex vivo expansion and transfer of BKPyV-specific cytotoxic T cells prepared from third-party donors may enhance virus-specific treatment, but the efficacy seems suboptimal.
To optimize BKPyV-specific T-cell expansion protocols, we compared conventional and G-Rex expansion cultures at 10 and 14 d after stimulation with BKPyV overlapping peptide pools. Cytokine and cytotoxic responses were assessed as well as programmed cell death protein 1 (PD-1) and programmed cell death ligand 1 (PD-1L) expression on effector and target cells, respectively.
Despite all donors being BKPyV-IgG seropositive, BKPyV-specific T-cell responses were heterogeneous and varied in magnitude between individuals. Overall, we observed higher cell counts in G-Rex compared to conventional cultures. Upon restimulation with 15mer-pools or immunodominant 9mer-pools, expanded BKPyV-specific T cells expressed polyfunctional markers, for example, interferon-γ, tumor necrosis factor-α and CD107a, and were cytotoxic for 9mP-pulsed autologous phytohemagglutinin blasts or BKPyV-infected allogeneic renal proximal tubule epithelial cells (RPTECs). Compared with conventional cultures, G-Rex-expanded CD4 and CD8 T cells showed higher PD-1 expression. Pembrolizumab reduced PD-1 expression on BKPyV-specific T cells and augmented polyfunctional BKPyV-specific T-cell responses and cytotoxicity. Interferon-𝛾 increased PD-L1 expression on BKPyV-infected RPTECs and increased viability.
Upregulated PD-1 expression of ex vivo expanded T cells contributes to third-party donor variability and potentially impairs the efficacy of adoptive T-cell therapy. Because BKPyV-infected RPTECs increase PD-L1 under inflammatory conditions, adding immune checkpoint inhibitors ex vivo before infusion could be evaluated for enhanced clinical efficacy when attempting treatment of BKPyV-associated pathologies without jeopardizing transplantation outcomes.
BK多瘤病毒（BKPyV）肾病是肾移植过早失败的主要原因。目前的治疗方法依赖于降低免疫抑制以恢复对BKPyV的特异性免疫控制。从第三方供体制备的BKPyV特异性细胞毒性T细胞的体外扩增和转移可能会增强病毒特异性治疗，但疗效似乎并不理想。
为了优化BKPyV特异性T细胞扩增方案，我们在用BKPyV重叠肽库刺激后10天和14天比较了传统培养和G-Rex扩增培养。评估了细胞因子和细胞毒性反应，以及效应细胞和靶细胞上程序性细胞死亡蛋白1（PD-1）和程序性细胞死亡配体1（PD-L1）的表达。
尽管所有供体的BKPyV-IgG均为血清阳性，但BKPyV特异性T细胞反应存在异质性，个体间反应强度不同。总体而言，我们观察到与传统培养相比，G-Rex培养中的细胞计数更高。在用15聚体库或免疫显性9聚体库再次刺激后，扩增的BKPyV特异性T细胞表达多功能标志物，例如干扰素-γ、肿瘤坏死因子-α和CD107a，并且对9mP脉冲的自体植物血凝素母细胞或BKPyV感染的同种异体肾近端小管上皮细胞（RPTEC）具有细胞毒性。与传统培养相比，G-Rex扩增的CD4和CD8 T细胞显示出更高的PD-1表达。帕博利珠单抗降低了BKPyV特异性T细胞上的PD-1表达，并增强了多功能BKPyV特异性T细胞反应和细胞毒性。干扰素-γ增加了BKPyV感染的RPTEC上的PD-L1表达并提高了细胞活力。
体外扩增T细胞中上调的PD-1表达导致第三方供体的变异性，并可能损害过继性T细胞疗法的疗效。由于BKPyV感染的RPTEC在炎症条件下会增加PD-L1，因此在尝试治疗BKPyV相关疾病而不危及移植结果时，可以评估在输注前体外添加免疫检查点抑制剂以提高临床疗效。
