Department of General Surgery, Fujian Medical University Union Hospital, Fuzhou, China.
Department of Oncology and Hematology and Division of Research, Kaiser Permanente, Santa Clara, CA, United States.
Front Endocrinol (Lausanne). 2023 Jun 6;14:1181538. doi: 10.3389/fendo.2023.1181538. eCollection 2023.
Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies with poor response to immune checkpoint inhibitors. The mechanism of such poor response is not completely understood.
We assessed T-cell receptor (TCR) repertoire and RNA expression at the single-cell level using high-dimensional sequencing of peripheral blood immune cells isolated from PDAC patients and from healthy human controls. We validated RNA-sequencing data by performing mass cytometry (CyTOF) and by measuring serum levels of multiple immune checkpoint proteins.
We found that proportions of T cells (CD45+CD3+) were decreased in PDAC patients compared to healthy controls, while proportion of myeloid cells was increased. The proportion of cytotoxic CD8+ T cells and the level of cytotoxicity per cell were increased in PDAC patients, with reduced TCR clonal diversity. We also found a significantly enriched S100A9+ monocyte population and an increased level of TIM-3 expression in immune cells of peripheral blood in PDAC patients. In addition, the serum level of soluble TIM-3 (sTIM-3) was significantly higher in PDAC patients compared to the non-PDAC participants and correlated with worse survival in two independent PDAC cohorts. Moreover, sTIM-3 exhibited a valuable role in diagnosis of PDAC, with sensitivity and specificity of about 80% in the training and validation groups, respectively. We further established an integrated model by combining sTIM-3 and carbohydrate antigen 19- 9 (CA19-9), which had an area under the curve of 0.974 and 0.992 in training and validation cohorts, respectively.
Our RNA-seq and proteomic results provide valuable insight for understanding the immune cell composition of peripheral blood of patients with PDAC.
胰腺导管腺癌（PDAC）是一种最致命的恶性肿瘤之一，对免疫检查点抑制剂的反应较差。这种较差反应的机制尚未完全阐明。
我们使用从 PDAC 患者和健康对照者分离的外周血免疫细胞的高维测序，在单细胞水平上评估 T 细胞受体（TCR）谱和 RNA 表达。我们通过进行质谱流式细胞术（CyTOF）和测量多种免疫检查点蛋白的血清水平来验证 RNA 测序数据。
与健康对照者相比，我们发现 PDAC 患者的 T 细胞（CD45+CD3+）比例降低，而髓样细胞比例增加。PDAC 患者的细胞毒性 CD8+T 细胞比例和每个细胞的细胞毒性水平增加，TCR 克隆多样性降低。我们还发现，在 PDAC 患者的外周血免疫细胞中，S100A9+单核细胞群显著富集，并且 TIM-3 表达水平增加。此外，与非 PDAC 参与者相比，PDAC 患者的可溶性 TIM-3（sTIM-3）血清水平显著升高，并且在两个独立的 PDAC 队列中与更差的生存相关。此外，sTIM-3 在诊断 PDAC 方面具有重要作用，在训练组和验证组中的敏感性和特异性分别约为 80%。我们通过结合 sTIM-3 和碳水化合物抗原 19-9（CA19-9）建立了一个综合模型，在训练和验证队列中的 AUC 分别为 0.974 和 0.992。
我们的 RNA-seq 和蛋白质组学结果为理解 PDAC 患者外周血免疫细胞组成提供了有价值的见解。
