Role of intratumoral high endothelial venules in tumor immunity

项目摘要 免疫检查点抑制成为有前途的癌症治疗策略。然而，只有一个子集 目前患者对这些疗法有反应。大量的临床证据表明， 效应T细胞和B细胞的浸润是免疫检查点抑制成功的先决条件 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，这使得肿瘤 对免疫疗法没有反应高内皮微静脉（HEV）是专门的微静脉， 血管是幼稚淋巴细胞募集的通道，这些血管可以在肿瘤中异位发育。高 肿瘤中的HEV密度与良好的临床结果相关，这表明促进肿瘤内的HEV治疗是有效的。 HEV的形成将为改善免疫疗法提供新的机会。小型GTTR-Ras天平 血管生成发芽和血管成熟，并使肿瘤血管正常化。若干条证据 表明R-Ras对于肿瘤内HEV形成的重要性。我们假设瘤内HEV 通过淋巴细胞的有效募集来塑造肿瘤免疫景观，从而创造 免疫刺激微环境有利于免疫检查点抑制疗法。我们提出了一个关键的 R-Ras通过促进肿瘤中HEV的形成而在此过程中发挥作用。 使用内皮细胞中R-Ras功能丧失和获得的新遗传模型，Aim 1将证明 R-Ras促进肿瘤血管系统内HEV的形成，并确定这些HEV如何影响肿瘤血管系统。 免疫原性小鼠中T细胞、B细胞、树突状细胞和其它免疫细胞类型的肿瘤浸润 乳腺肿瘤和黑素瘤。还将研究肿瘤内HEV对细胞因子环境的影响。 测定将通过免疫荧光、ELISA、FACS和RNAseq进行分析。临床 将对癌症样本进行检查，以证实小鼠研究的结果。目标2将在功能上 表征肿瘤HEV并分析肿瘤内HEV募集的T细胞对特异性抗原的致敏， 将幼稚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抑制疗法的反应性。 作为T细胞/B细胞向肿瘤募集的通道，肿瘤内HEV是潜在的重编程新靶点 肿瘤免疫景观和改善患者对免疫检查点抑制剂的反应。预期 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.