Role of cDC2 subsets in host protection and CD4T cell responses in melanoma

项目摘要 尽管最近取得了成功，但许多黑色素瘤患者仍然未能对免疫疗法作出反应，并且存在免疫缺陷。 迫切需要确定新的治疗靶点。免疫疗法的主要目标是激活肿瘤- 特异性免疫反应，其中肿瘤特异性T细胞发挥关键作用。虽然细胞毒性CD 8 T细胞 长期以来一直是肿瘤特异性免疫研究的主要焦点，越来越多的证据表明， 这表明CD 4 T细胞对肿瘤排斥的贡献，特别是在用免疫原性疗法治疗的肿瘤中。然而，在这方面， 与CD 8 T细胞相比，对黑素瘤中CD 4 T细胞活化的机制了解较少。 2型常规树突状细胞（cDC 2）具有高的抗原呈递能力，以激活抗原特异性免疫应答。 CD 4 T细胞，但其在肿瘤免疫中的作用尚未完全了解，部分原因是由于表型 这种细胞类型的异质性。我们先前将CD 301 b + DCs鉴定为CD 301 b + DCs中主要的cDC 2群体。 小鼠皮肤，并表明它们将抗原从皮肤转运到引流淋巴结， 致敏抗原特异性CD 4 T细胞。本提案侧重于了解它们在主机保护中的作用， 小鼠实验性黑色素瘤模型中的CD 4 T细胞活化。为了了解cDC 2细胞如何响应 为了在分子水平上研究肿瘤微环境，我们采用了一种新的单细胞RNA测序技术， 鉴定黑色素瘤进展过程中cDC 2亚群中亚群特异性基因表达变化。同时， 我们使用靶向细胞耗竭方法来确定依赖cDC 2的宿主的细胞机制， 在未治疗的黑素瘤以及用免疫原性疗法治疗的那些中的保护。这些 这些实验将共同提供对cDC 2亚群在黑色素瘤中作用的全面理解。 并可能揭示导致黑色素瘤特异性CD 4 T细胞活化的新细胞途径。

Project Summary Despite recent successes, many melanoma patients still fail to respond to immunotherapy and there is a pressing need for identifying novel therapeutic targets. The primary goal of immunotherapy is to activate tumor- specific immune responses, in which tumor-specific T cells play a crucial role. Although cytotoxic CD8T cells have long been the main focus of research on tumor-specific immunity, growing evidence shows the contribution of CD4T cells to tumor rejection, especially in tumors treated with immunogenic therapy. However, the mechanism of CD4T cell activation in melanoma is less well understood compared to that of CD8T cells. Type 2 conventional dendritic cells (cDC2s) have high antigen presenting capacity to activate antigen-specific CD4T cells, but their role in tumor immunity has not been fully understood due partially to the phenotypic heterogeneity within this cell type. We previously identified CD301b+ DCs as the major cDC2 population in the mouse skin and showed that they transport antigens from the skin to the draining lymph node and efficiently prime antigen-specific CD4T cells. This proposal focuses on understanding their role in host protection and CD4T cell activation in experimental melanoma models in mice. To understand how cDC2 cells respond to the tumor microenvironment at the molecular level, we employ a novel technique of single-cell RNA sequencing to identify subset-specific gene expression changes in cDC2 subsets during melanoma progression. In parallel, we use targeted cell depletion approaches to identify the cellular mechanisms of cDC2-depedent host protection in both untreated melanoma as well as in those treated with immunogenic therapy. These experiments will collectively provide comprehensive understanding on the role of cDC2 subsets in melanoma and potentially reveal new cellular pathways that lead to activation of melanoma-specific CD4T cells.