Effect of radiotherapy on dendritic cell subsets: implications for immunotherapy

项目摘要 为了回答NCI的挑衅性问题#11，我们建议研究 放射治疗（RT）对树突状细胞（DC）和其他骨髓细胞功能的影响，以及这些机制如何 影响免疫治疗的效果。鉴于它们在激活和调节新抗原方面的独特作用- 我们的长期目标是利用DC进行免疫治疗。目前还 我们对RT对DC亚群和其他髓系细胞的作用的理解存在根本性的机制空白 肿瘤微环境（TME）。这一差距代表了理性的一个重要问题 RT与免疫疗法的组合。最近在无肿瘤小鼠中的数据表明， (IR)差异性地影响DC亚群，导致免疫原性而非耐受原性DC的快速死亡。 此外，IR改变了DC亚群的基因特征，从而改变了它们促进细胞增殖的能力。 抗原特异性调节性T细胞（Tcells）。因此，皮肤暴露于IR促进肿瘤的生长 通过依赖于致耐受性DC亚群的机制，在IR暴露后1天移植， 你好基于这些发现，我们假设肿瘤局部RT将诱导肿瘤细胞中的 通过促进致耐受性DC的存活和功能，定位于TME中的DC亚群，这反过来将 诱导T细胞介导耐受。我们进一步假设IR对DC亚群的这种未研究的作用， 其他髓样细胞将显著影响RT/免疫治疗组合策略的结果。在三 具体的目的，我们建议执行一个公正的表征髓细胞定位在TME 在肿瘤靶向RT和RT/免疫疗法组合使用新的可用技术，CyTOF， 和RNA-seq.我们将使用类似于黑色素瘤患者驱动突变的小鼠模型，并成像- 引导RT，允许分级和立体定向输送方案，类似于临床中使用的方案 实践我们将这些特征与肿瘤特异性T细胞反应的产生相关联。我们 预计从这项提案中获得的发现将增强我们目前对DC生物学的理解， 功能反应RT，并积极影响组合策略的合理设计。

PROJECT SUMMARY In response to NCI’s Provocative Question #11, we propose to investigate the mechanisms of action of radiotherapy (RT) on the function of dendritic cells (DCs) and other myeloid cells, and how these mechanisms affect the efficacy of immunotherapies. Given their unique role in activating and modulating new antigen- specific T cell immune responses, our long-term goal is to harness DCs for immunotherapy. Currently, there is a fundamental mechanistic gap in our understanding of the effect of RT on DC subsets and other myeloid cells localized in the tumor microenvironment (TME). This gap represents an important problem for the rational combination of RT with immunotherapies. Recent data in tumor-free mice demonstrated that ionizing radiation (IR) differentially affects DC subsets, causing the rapid death of immunogenic but not tolerogenic DCs. Furthermore, IR changes the gene signature of DC subsets and, consequently, their capacity to promote antigen-specific regulatory T cells (Tregs). Therefore, exposure of skin to IR promotes the growth of tumors transplanted one-day post-IR exposure through a mechanism dependent on tolerogenic DC subsets and Tregs. Based on these findings, we hypothesize that tumor-localized RT will induce a shift in the proportion of DC subsets localized in the TME by promoting the survival and function of tolerogenic DCs, which in turn will induce T cell-mediated tolerance. We further hypothesize that this unstudied effect of IR on DC subsets and other myeloid cells will significantly impact the outcome of RT/immunotherapy combination strategies. In three specific aims, we propose to perform an unbiased characterization of myeloid cells localized in the TME following tumor-targeted RT and RT/immunotherapy combinations using newly available technology, CyTOF, and RNA-seq. We will use mouse models that resemble melanoma-driving mutations in patients, and image- guided RT that allows for fractionation and stereotactic delivery schemes similar to those used in clinical practice. We will correlate these characterizations with the generation of tumor-specific T cell responses. We anticipate that findings obtained from this proposal will enhance our current understanding of DC biology and function in response to RT, and positively impact the rational design of combination strategies.