Interrupting the nitrosative stress fuels tumor-specific cytotoxic T lymphocytes in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest tumors owing to its robust desmoplasia, low immunogenicity, and recruitment of cancer-conditioned, immunoregulatory myeloid cells. These features strongly limit the success of immunotherapy as a single agent, thereby suggesting the need for the development of a multitargeted approach. The goal is to foster T lymphocyte infiltration within the tumor landscape and neutralize cancer-triggered immune suppression, to enhance the therapeutic effectiveness of immune-based treatments, such as anticancer adoptive cell therapy (ACT).We examined the contribution of immunosuppressive myeloid cells expressing arginase 1 and nitric oxide synthase 2 in building up a reactive nitrogen species (RNS)-dependent chemical barrier and shaping the PDAC immune landscape. We examined the impact of pharmacological RNS interference on overcoming the recruitment and immunosuppressive activity of tumor-expanded myeloid cells, which render pancreatic cancers resistant to immunotherapy.PDAC progression is marked by a stepwise infiltration of myeloid cells, which enforces a highly immunosuppressive microenvironment through the uncontrolled metabolism of L-arginine by arginase 1 and inducible nitric oxide synthase activity, resulting in the production of large amounts of reactive oxygen and nitrogen species. The extensive accumulation of myeloid suppressing cells and nitrated tyrosines (nitrotyrosine, N-Ty) establishes an RNS-dependent chemical barrier that impairs tumor infiltration by T lymphocytes and restricts the efficacy of adoptive immunotherapy. A pharmacological treatment with AT38 ([3-(aminocarbonyl)furoxan-4-yl]methyl salicylate) reprograms the tumor microenvironment from protumoral to antitumoral, which supports T lymphocyte entrance within the tumor core and aids the efficacy of ACT with telomerase-specific cytotoxic T lymphocytes. Tumor microenvironment reprogramming by ablating aberrant RNS production bypasses the current limits of immunotherapy in PDAC by overcoming immune resistance. Overall design: Characterization of immune cells infiltrating PDAC in C57Bl/6 mice treated or not with AT38 using Chromium 10x single-cell RNA-seq (scRNA-seq) data.

胰腺导管腺癌（PDAC）是致死率最高的恶性肿瘤之一，其具有显著的促结缔组织增生、低免疫原性，以及募集肿瘤教育性免疫调节髓系细胞的特征。这些特征极大限制了单药免疫治疗的疗效，因此亟需开发多靶点治疗策略。该策略的目标是促进T淋巴细胞向肿瘤微环境浸润，并抵消癌症诱导的免疫抑制，以提升免疫治疗手段的疗效，例如抗肿瘤过继细胞疗法（ACT）。
本研究探究了表达精氨酸酶1（arginase 1）与一氧化氮合酶2的免疫抑制性髓系细胞，在构建活性氮物种（RNS）依赖性化学屏障及塑造PDAC免疫微环境中的作用；同时考察了药物干预RNS对逆转肿瘤扩增髓系细胞募集中与免疫抑制活性的影响——这类细胞会使胰腺癌对免疫治疗产生耐药性。
PDAC进展以髓系细胞的渐进性浸润为特征，这类细胞通过精氨酸酶1与诱导型一氧化氮合酶介导的L-精氨酸无序代谢，生成大量活性氧与活性氮物种，从而构筑高度免疫抑制的肿瘤微环境。免疫抑制性髓系细胞与硝基化酪氨酸（nitrotyrosine，N-Ty）的大量蓄积，会构建出RNS依赖性化学屏障，阻碍T淋巴细胞向肿瘤内浸润，并限制过继免疫治疗的疗效。
采用AT38（[3-(氨基羰基)呋咱-4-基]甲基水杨酸酯）进行药物治疗，可将肿瘤微环境从促瘤表型重编程为抗肿瘤表型，促进T淋巴细胞向肿瘤实质浸润，并增强端粒酶特异性细胞毒性T淋巴细胞过继细胞疗法的疗效。通过清除异常RNS生成来重编程肿瘤微环境，可通过逆转免疫耐药性，突破PDAC免疫治疗当前的局限性。
整体实验设计：利用Chromium 10x单细胞RNA测序（scRNA-seq）数据，对经AT38处理与未处理的C57BL/6小鼠中浸润PDAC的免疫细胞进行表征分析。