Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden.
Department of Pathology/Cytology, Karolinska University Hospital, Stockholm, Sweden.
Front Immunol. 2019 Apr 24;10:847. doi: 10.3389/fimmu.2019.00847. eCollection 2019.
Carcinoma-associated pancreatic fibroblasts (CAFs) are the major type of cells in the stroma of pancreatic ductal adenocarcinomas and besides their pathological release of extracellular matrix proteins, they are also perceived as key contributors to immune evasion. Despite the known relevance of tumor infiltrating lymphocytes in cancers, the interactions between T-cells and CAFs remain largely unexplored. Here, we found that CAFs isolated from tumors of pancreatic cancer patients undergoing surgical resection ( = 15) expressed higher levels of the PD-1 ligands PD-L1 and PD-L2 compared to primary skin fibroblasts from healthy donors. CAFs strongly inhibited T-cell proliferation in a contact-independent fashion. Blocking the activity of prostaglandin E (PGE) by indomethacin partially restored the proliferative capacity of both CD4 and CD8 T-cells. After stimulation, the proportion of proliferating T-cells expressing HLA-DR and the proportion of memory T-cells were decreased when CAFs were present compared to T-cells proliferating in the absence of CAFs. Interestingly, CAFs promoted the expression of TIM-3, PD-1, CTLA-4 and LAG-3 in proliferating T-cells. Immunohistochemistry stainings further showed that T-cells residing within the desmoplastic stromal compartment express PD-1, indicating a role for CAFs on co-inhibitory marker expression also . We further found that PGE promoted the expression of PD-1 and TIM-3 on T-cells. Functional assays showed that proliferating T-cells expressing immune checkpoints produced less IFN-γ, TNF-α, and CD107a after restimulation when CAFs had been present. Thus, this indicates that CAFs induce expression of immune checkpoints on CD4 and CD8 T-cells, which contribute to a diminished immune function.
癌相关胰腺成纤维细胞（CAFs）是胰腺导管腺癌基质中主要的细胞类型，除了它们病理性地释放细胞外基质蛋白外，它们还被认为是免疫逃逸的关键贡献者。尽管已知肿瘤浸润淋巴细胞在癌症中的相关性，但 T 细胞与 CAFs 之间的相互作用在很大程度上仍未得到探索。在这里，我们发现从接受手术切除的胰腺癌患者的肿瘤中分离出的 CAFs（= 15）与来自健康供体的原代皮肤成纤维细胞相比，表达更高水平的 PD-1 配体 PD-L1 和 PD-L2。CAFs 以非接触依赖性方式强烈抑制 T 细胞增殖。用吲哚美辛阻断前列腺素 E（PGE）的活性部分恢复了 CD4 和 CD8 T 细胞的增殖能力。刺激后，与 T 细胞在没有 CAFs 的情况下增殖相比，当存在 CAFs 时，增殖 T 细胞中表达 HLA-DR 的 T 细胞的比例和记忆 T 细胞的比例降低。有趣的是，CAFs 促进了增殖 T 细胞中 TIM-3、PD-1、CTLA-4 和 LAG-3 的表达。免疫组织化学染色进一步表明，位于纤维性基质隔室中的 T 细胞表达 PD-1，表明 CAFs 在共抑制标志物表达上也发挥作用。我们进一步发现 PGE 促进了 T 细胞上 PD-1 和 TIM-3 的表达。功能测定表明，当存在 CAFs 时，表达免疫检查点的增殖 T 细胞在再刺激后产生的 IFN-γ、TNF-α和 CD107a 减少。因此，这表明 CAFs 诱导 CD4 和 CD8 T 细胞表达免疫检查点，这导致免疫功能下降。
