Senescent cancer-associated fibroblasts in pancreatic adenocarcinoma suppress CD8+ T cell activation and inhibit response to immune checkpoint therapy [Cultured_Human_Mouse]. Senescent cancer-associated fibroblasts in pancreatic adenocarcinoma suppress CD8+ T cell activation and inhibit response to immune checkpoint therapy [Cultured_Human_Mouse]

Senescent cells appear within tumors and their stroma, exerting complex pro- and anti-tumorigenic functions. The effects of senescent tumor stromal cells are mostly unknown, as is the potential for targeting such senescent cells for improved therapy. Here we uncover the presence of a senescent subset of cancer-associated fibroblasts (CAFs) within pancreatic adenocarcinomas and in premalignant pancreatic lesions. Senescent CAFs show reduced proliferation, and are often associated with the inflammatory CAF (iCAF) subtype. We isolated and characterized senescent CAFs from mouse models and directly from human patients, and found that they express elevated levels of immune-regulatory genes. In a panel of mouse PDACs, high levels of senescent CAFs correlated with low T cell infiltration. Removal of senescent CAFs from PDAC stroma, either genetically or through treatment with the senolytic drug ABT-199 (venetoclax), a Bcl2 inhibitor, increased rates of activated cytotoxic CD8+ T cells within tumors. Conversely, activation of CAF senescence within PDACs led to reduced CD8+ T cell numbers. Media from senescent PDAC CAFs inhibited T cell proliferation and activation. We show that implanted PDAC tumors show improved response to immune checkpoint therapy when co-treated with the senolytic drug. These results reveal that the presence of senescent CAFs in PDAC stroma acts to repress cytotoxic T cell activity, and suggest that their targeted elimination through senolytic treatment may enhance immunotherapy. Overall design: Senescence was induced in cultured primary mouse and human PDAC CAFs using a CRE-ER inducible system, and transcriptomes were analyzed.

衰老细胞（senescent cells）可出现于肿瘤及其间质（stroma）中，发挥复杂的促瘤与抑瘤功能。目前对于衰老的肿瘤间质细胞的作用大多尚不明确，靶向这类衰老细胞以优化治疗方案的潜力也未被充分阐明。本研究首次揭示了胰腺腺癌及癌前胰腺病变中存在癌症相关成纤维细胞（cancer-associated fibroblasts, CAFs）的衰老亚群。衰老型CAFs增殖能力显著降低，且常与炎症型CAF（inflammatory CAF, iCAF）亚型相关联。我们从小鼠模型及人类患者体内分离并鉴定了衰老型CAFs，发现其免疫调节基因的表达水平显著升高。在一组小鼠胰腺导管腺癌（pancreatic ductal adenocarcinoma, PDAC）队列中，高水平的衰老型CAFs与低T细胞浸润程度相关。通过遗传学手段或使用衰老清除药物（senolytic drug）ABT-199（venetoclax，一种Bcl-2抑制剂）清除PDAC间质中的衰老型CAFs，可提升肿瘤内活化的细胞毒性CD8+ T细胞的比例。反之，诱导PDAC中CAFs的衰老状态，则会导致CD8+ T细胞数量减少。衰老型PDAC CAFs的培养上清可抑制T细胞的增殖与活化。我们发现，当与衰老清除药物联合治疗时，移植的PDAC肿瘤对免疫检查点疗法的响应得到改善。上述结果表明，PDAC间质中的衰老型CAFs会抑制细胞毒性T细胞的活性，并提示通过衰老清除疗法靶向清除这类细胞或可增强免疫治疗效果。总体实验设计：采用CRE-ER诱导系统，对体外培养的原代小鼠及人类PDAC CAFs诱导细胞衰老，并对其转录组进行分析。