Regulation and role of fibroblast-derived interleukin-33 in the pancreatic tumor microenvironment

项目总结/摘要 胰腺导管腺癌（PDA）是一种高度致命的疾病，五年生存率仅为10%。 PDA肿瘤体积的大部分由反应性纤维炎性肿瘤微环境组成， 有助于肿瘤的生长和维持。胰腺癌的高度免疫抑制特性 肿瘤微环境也是免疫治疗持续无效的部分原因 在PDA患者中。尽管之前有许多研究检查了PDA的不同方面， 尽管有免疫抑制，但关于细胞间的复杂网络仍有许多未知之处。 调节这种现象的串扰。我们之前的工作已经证明浸润的巨噬细胞 是PDA中免疫抑制的重要介质，它们的极化受到以下表达的影响： 肿瘤细胞中致癌Kras的表达。其他研究小组已经描述了某些药物的免疫抑制作用， 胰腺肿瘤微环境中的成纤维细胞亚群。本文中描述的初步实验 一项提案证明了成纤维细胞、巨噬细胞和肿瘤细胞之间通过成纤维细胞的联系 细胞因子白细胞介素-33（IL 33）的表达。IL 33在癌症生物学中的作用是有争议的，其 对肿瘤的总体作用被认为是支持性或抑制性的，这取决于癌症背景。在这里， 结果显示IL 33丰度与疾病进展相关， 依赖于来自肿瘤细胞的致癌Kras驱动信号。此外，我们还完成了一个试点项目， 我们将胰腺肿瘤细胞原位植入同基因的 在成纤维细胞中缺乏Il 33的工程化小鼠模型（Il 33 f/f，Pdgfra-CreERT 2/+）。来自I133缺陷型小鼠的肿瘤 肿瘤生长较慢，巨噬细胞浸润呈下降趋势，表明成纤维细胞来源的 IL 33既促进肿瘤，又可能在免疫抑制性巨噬细胞的募集中发挥作用。 因此，本研究的总体目标是阐明导致这种变化的细胞相互作用。 PDA免疫抑制的建立和维持，中心假设是成纤维细胞 衍生的IL 33是胰腺肿瘤微环境中免疫抑制的关键调节剂， 调节巨噬细胞浸润。将通过以下两个目标对这一假设进行研究： (Aim 1）确定IL 33在癌症相关成纤维细胞中的调节和作用，以及（目的2）评估IL 33对癌症相关成纤维细胞的影响。 IL 33对肿瘤相关巨噬细胞募集的影响。为了完成这项调查， 将使用肿瘤细胞、成纤维细胞和巨噬细胞培养物进行体外测定。我们还将继续 利用Il 33 f/f，Pdgfra-CreERT 2/+基因工程小鼠模型来评估IL 33依赖性变化， 胰腺肿瘤的免疫抑制特性这项研究积累的数据将进一步推动该领域的 了解PDA的免疫抑制调节，从而带来有效的免疫治疗 更接近成为一种可行的治疗选择。

PROJECT SUMMARY/ABSTRACT Pancreatic ductal adenocarcinoma (PDA) is a highly deadly disease with a five-year survival rate of only 10%. The bulk of the PDA tumor volume is composed of a reactive fibroinflammatory tumor microenvironment that assists in the growth and maintenance of the tumor. The highly immunosuppressive nature of the pancreatic tumor microenvironment is also responsible, in part, for the continued inefficacy of immunotherapy treatments in PDA patients. Despite numerous studies that have previously examined different facets of PDA immunosuppression, there is still much that is unknown regarding the complex network of intercellular crosstalk that regulates this phenomenon. Our previous work has demonstrated that infiltrating macrophages are essential mediators of immunosuppression in PDA, and that their polarization is affected by the expression of oncogenic Kras in tumor cells. Other groups have characterized the immunosuppressive impact of certain fibroblast subgroups within the pancreatic tumor microenvironment. Preliminary experiments described in this proposal demonstrate a connection between fibroblasts, macrophages, and tumor cells through fibroblast expression of the cytokine interleukin-33 (IL33). The role of IL33 in cancer biology is controversial, with its overall effect on the tumor thought to be supportive or suppressive depending on the cancer context. Here, results show that IL33 abundance correlates with disease progression and that fibroblast expression of IL33 is dependent on oncogenic Kras-driven signals from tumor cells. Additionally, we have completed a pilot experiment whereby we have orthotopically implanted pancreatic tumor cells into a syngeneic genetically engineered mouse model lacking Il33 in fibroblasts (Il33f/f, Pdgfra-CreERT2/+). Tumors from Il33-deficient mice had slower tumor growth and a trending decrease in macrophage infiltration, suggesting that fibroblast-derived Il33 is both tumor promoting and may play a role in the recruitment of immunosuppressive macrophages. Therefore, the overall objective of this study is to elucidate the cellular interactions that contribute to the establishment and maintenance of immunosuppression in PDA, and the central hypothesis is that fibroblast derived IL33 is a key regulator of immunosuppression in the pancreatic tumor microenvironment through its modulation of macrophage infiltration. This hypothesis will be investigated through the following two Aims: (Aim 1) define the regulation and role of IL33 in cancer-associated fibroblasts, and (Aim 2) assess the impact of IL33 on the recruitment of tumor-associated macrophages. To complete this investigation, a combination of in vitro assays using tumor cell, fibroblast, and macrophage cultures will be performed. We also will continue to utilize the Il33f/f, Pdgfra-CreERT2/+ genetically engineered mouse model to assess Il33-dependent changes in the immunosuppressive nature of pancreatic tumors. The data accumulated by this study will further the field’s understanding of immunosuppression regulation in PDA, and consequentially bring effective immunotherapy strategies one step closer to becoming a viable therapeutic option.