Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia.
Australian Research Council Centre of Excellence in Advanced Molecular Imaging, University of Melbourne, Melbourne, Victoria, Australia.
Cancer Immunol Res. 2021 Jun;9(6):612-623. doi: 10.1158/2326-6066.CIR-20-0817. Epub 2021 Mar 5.
Merkel cell carcinomas (MCC) are immunogenic skin cancers associated with viral infection or UV mutagenesis. To study T-cell infiltrates in MCC, we analyzed 58 MCC lesions from 39 patients using multiplex-IHC/immunofluorescence (m-IHC/IF). CD4 or CD8 T cells comprised the majority of infiltrating T lymphocytes in most tumors. However, almost half of the tumors harbored prominent CD4/CD8 double-negative (DN) T-cell infiltrates (>20% DN T cells), and in 12% of cases, DN T cells represented the majority of T cells. Flow cytometric analysis of single-cell suspensions from fresh tumors identified DN T cells as predominantly Vδ2 γδ T cells. In the context of γδ T-cell inflammation, these cells expressed PD-1 and LAG3, which is consistent with a suppressed or exhausted phenotype, and CD103, which indicates tissue residency. Furthermore, single-cell RNA sequencing (scRNA-seq) identified a transcriptional profile of γδ T cells suggestive of proinflammatory potential. T-cell receptor (TCR) analysis confirmed clonal expansion of Vδ1 and Vδ3 clonotypes, and functional studies using cloned γδ TCRs demonstrated restriction of these for CD1c and MR1 antigen-presenting molecules. On the basis of a 13-gene γδ T-cell signature derived from scRNA-seq analysis, gene-set enrichment on bulk RNA-seq data showed a positive correlation between enrichment scores and DN T-cell infiltrates. An improved disease-specific survival was evident for patients with high enrichment scores, and complete responses to anti-PD-1/PD-L1 treatment were observed in three of four cases with high enrichment scores. Thus, γδ T-cell infiltration may serve as a prognostic biomarker and should be explored for therapeutic interventions..
默克尔细胞癌（Merkel cell carcinoma，MCC）是一种与病毒感染或 UV 诱变相关的免疫原性皮肤癌。为了研究 MCC 中的 T 细胞浸润，我们使用多重免疫组化/免疫荧光（m-IHC/IF）分析了 39 名患者的 58 个 MCC 病变。在大多数肿瘤中，CD4 或 CD8 T 细胞构成了浸润性 T 淋巴细胞的主要部分。然而，近一半的肿瘤存在显著的 CD4/CD8 双阴性（DN）T 细胞浸润（>20%DN T 细胞），在 12%的病例中，DN T 细胞代表了大多数 T 细胞。对新鲜肿瘤单细胞悬液的流式细胞术分析鉴定出 DN T 细胞主要为 Vδ2 γδ T 细胞。在 γδ T 细胞炎症的背景下，这些细胞表达 PD-1 和 LAG3，这与受抑制或耗竭的表型一致，并且表达 CD103，表明组织驻留。此外，单细胞 RNA 测序（scRNA-seq）鉴定出 γδ T 细胞的转录谱提示其具有促炎潜能。T 细胞受体（TCR）分析证实了 Vδ1 和 Vδ3 克隆型的克隆扩增，并且使用克隆 γδ TCR 的功能研究表明，这些 TCR 受限于 CD1c 和 MR1 抗原呈递分子。基于 scRNA-seq 分析得出的 13 个基因 γδ T 细胞特征，对批量 RNA-seq 数据的基因集富集分析显示，富集分数与 DN T 细胞浸润之间存在正相关。具有高富集分数的患者具有明显改善的疾病特异性生存，并且在四个具有高富集分数的病例中有三个观察到对抗 PD-1/PD-L1 治疗的完全反应。因此，γδ T 细胞浸润可作为一种预后生物标志物，并应探索用于治疗干预。
