Role of intratumoral high endothelial venules in tumor immunity

项目摘要 免疫检查点抑制成为很有希望的癌症治疗策略。然而，只有 目前，患者对这些疗法有反应。重要的临床证据表明，大量的肿瘤 免疫检查点抑制成功的先决条件是效应性T细胞和B细胞的渗透 治疗。然而，这些淋巴细胞在很大程度上被排除在许多患者的肿瘤之外，这就造成了肿瘤 对免疫疗法没有反应。高内皮微静脉(HEV)是一种特殊的小静脉，其作用是 原始淋巴细胞募集的通道，这些血管可以在肿瘤中异位发育。高 肿瘤中HEV的密度与良好的临床结果相关，提示肿瘤内的促进 HEV的形成将为改进免疫疗法提供一个新的机会。小分子GTPase R-RAS平衡 血管生成发芽和血管成熟，使肿瘤血管正常化。有几条证据 提示R-RAS在肿瘤内HEV形成中的重要性。我们假设肿瘤内的HEV 通过高效地募集淋巴细胞来塑造肿瘤免疫格局，从而创造 有利于免疫检查点抑制治疗的免疫刺激微环境。我们提出了一个关键的 通过促进肿瘤中HEV的形成，R-RAS在这一过程中的作用。 使用R-RAS在内皮细胞中功能丧失和获得的新遗传模型，Aim 1将证明 R-RAS促进肿瘤血管内HEV的形成，并决定这些HEV如何影响 免疫原性小鼠肿瘤对T细胞、B细胞、树突状细胞等免疫细胞的侵袭 乳腺肿瘤和黑色素瘤。肿瘤内HEV对细胞因子环境的影响也将是 下定决心。这些分析将通过免疫荧光、ELISA、FACS和RNAseq进行。临床 癌症样本将被检查，以证实老鼠研究的发现。AIM 2将在功能上 肿瘤HEV的特征和分析HEV招募的T细胞对特定抗原的瘤内启动 单纯OT-1 T细胞过继转移至表达OVA的肿瘤。目标3将确定瘤内HEV如何 影响肿瘤的免疫破坏和对PD-1/PD-L1抑制治疗的反应性。 作为T细胞/B细胞向肿瘤募集的门户，瘤内HEV是潜在的新的编程目标 改善肿瘤免疫格局，改善患者对免疫检查点抑制剂的反应。预期中的 这项研究的结果将为这些想法提供概念验证。

Project Summary Immune checkpoint inhibition emerged as promising cancer treatment strategies. However, only a subset of patients respond to these therapies at present. Significant clinical evidence indicates that abundant tumor infiltration of effector T cells and B cells is a prerequisite for the success of the immune checkpoint inhibition therapies. However, these lymphocytes are largely excluded from many patients' tumors, which makes the tumor unresponsive to the immunotherapies. High endothelial venules (HEV) are specialized venules that serve as gateways for naïve lymphocyte recruitment, and these blood vessels can develop ectopically in tumors. High HEV density in tumors correlate with favorable clinical outcomes, suggesting that the promotion of intratumoral HEV formation would offer a novel opportunity to improve immunotherapies. The small GTPase R-Ras balances angiogenic sprouting and vessel maturation, and normalizes tumor blood vessels. Several lines of evidence indicate the importance of R-Ras for the formation of intratumoral HEVs. We hypothesize that intratumoral HEVs shape the tumor immune landscape through efficient recruitment of lymphocytes, thereby creating the immunostimulatory microenvironment favorable for immune checkpoint inhibition therapies. We propose a critical role of R-Ras in this process by facilitating HEV formation in tumors. Using novel genetic models of loss- and gain-of-function of R-Ras in endothelial cells, Aim 1 will demonstrate that R-Ras facilitates the formation of HEVs within the tumor vasculature and determine how these HEVs affect the tumor infiltration of T cells, B cells, dendritic cells, and other immune cell types in immunogenic mouse mammary tumor and melanoma. The influence of intratumoral HEVs on cytokine environment will also be determined. The analyses will be conducted by immunofluorescence, ELISA, FACS, and RNAseq. Clinical cancer specimens will be examined to corroborate the findings from the mouse studies. Aim 2 will functionally characterize tumor HEVs and analyze intratumoral priming of HEV-recruited T cells to a specific antigen using adoptive transfer of naïve OT-1 T cells to OVA-expressing tumors. Aim 3 will determine how intratumoral HEVs impact the immune destruction of tumors and the responsiveness to PD-1/PD-L1 inhibition therapies. As the gateways for T cell/B cell recruitment to tumors, intratumoral HEVs are potential new targets to reprogram the tumor immune landscape and to improve patients' response to immune checkpoint inhibitors. The expected outcome of this study will provide the proof-of-concept for such ideas.