Atypical Chemokine Receptor 4 (ACKR4) in Anti-tumor Immunity in colorectal cancer

摘要 结直肠癌(CRC)仍然是美国与癌症相关的死亡的第三大常见原因。 大多数结直肠癌是非免疫原性的，即它们缺乏显著的抗肿瘤免疫强度。 反应，通常对显著改变方式的免疫疗法无反应 我们治疗许多癌症患者。几种趋化因子和细胞因子与结直肠癌免疫有关 回应。结直肠癌未被研究的特征之一是通过调节抗肿瘤免疫 非典型趋化因子受体4的表达。这种受体参与内化和 多种趋化因子的降解，如趋化因子(C-C基序)配体19(CCL19)和CCL21， 从而调节CC-趋化因子受体7(CCR7)/CCL19/CCL21的趋化作用及其 下游免疫反应。然而，ACKR4在免疫调节中的作用-包括 免疫细胞在CRC环境中的贩运和分化--仍有待调查。我们的 初步数据显示，ACKR4的过度表达与CD8+T细胞的高渗透相关 并与结直肠癌患者样本中的总体免疫应答(由“免疫评分”表示)进行比较。 因此，我们假设ACKR4对结直肠癌的免疫调节有积极的影响，并赋予 通过调节CCR7/CCL19/CCL21的趋化作用实现抗肿瘤免疫。在目标1中，我们将建立 ACKR4表达与结直肠癌抗肿瘤免疫的关系我们将生成正射影像 小鼠结直肠癌临床前模型通过小动物不同水平ACKR4的表达 内窥镜检查和微量注射。肿瘤体积、CD8+T细胞和NK细胞数量及关键细胞毒作用 将测量细胞因子。我们还将确定对ACKR4有反应的初级免疫细胞 在结直肠癌模型中的表达。目标2将破译抗肿瘤的机制和调控 CRC中ACKR4的豁免权。由于ACKR4是CCL19和CCL21的清除受体，我们将 关注CCR7/CCL19/CCL21趋化轴。结果将使用CCL21-/-进一步确认， CCL19-/-作为原位结直肠癌模型的宿主小鼠。 临床影响。这项先导性研究的结果将确立ACKR4的临床意义 表达水平对结直肠癌免疫反应的影响。作为一个结果，它将从根本上推进 我们对结直肠癌中抗肿瘤免疫是如何产生和调节的知识，并提供了新的 结直肠癌免疫疗法的靶点。

Abstract Colorectal cancer (CRC) remains the third most common cause of cancer-related deaths in the U.S. The majority of CRC tumors are non-immunogenic, i.e. they lack a significant intensity of anti-tumor immune response, and are typically unresponsive to immunotherapies that have dramatically changed the way we treat many cancer patients. Several chemokines and cytokines are implicated in CRC immune response. One of the under examined features of CRC is the regulation of anti-tumor immunity by atypical chemokine receptor 4 (ACKR4) expression. This receptor, is involved in the internalization and degradation of multiple chemokines, such as chemokine (C-C motif) ligand 19 (CCL19) and CCL21, thereby modulating the CC-chemokine receptor 7 (CCR7)/CCL19/CCL21 chemotaxis and its downstream immune responses. However, the role of ACKR4 in immune regulation— including the trafficking and differentiation of immune cells in a CRC environment—remains to be investigated. Our preliminary data showed that overexpression of ACKR4 is correlated with high CD8+ T-cell infiltration and with the overall immune response (indicated by the “immunoscore”) in CRC patients' samples. Therefore, we hypothesize that ACKR4 positively affects immune regulation in CRC and confers antitumor immunity by modulating CCR7/CCL19/CCL21 chemotaxis. In Aim 1, we will establish the connection between ACKR4 expression and anti-tumor immunity of CRC. We will generate orthotopic preclinical models mouse colorectal cancer different levels of ACKR4 expression levels via small animal endoscopy and microinjection. Tumor volume, numbers of CD8+ T cell and NK cells, and key cytotoxic cytokines will be measured. We will also determine the primary immune cells that respond to ACKR4 expression in CRC tumor models. Aim 2 will decipher the mechanisms and regulation of antitumor immunity by ACKR4 in CRC. Since ACKR4 is the scavenging receptor of CCL19 and CCL21, we will focus on the CCR7/CCL19/CCL21 chemotaxis axis. Results will be further confirmed using CCL21-/-, CCL19-/- as the host mice for orthotopic CRC models. Clinical Impact. The results from this pilot study will establish the clinical significance of ACKR4 expression levels to immune response in colorectal cancer. As an outcome, it will fundamentally advance our knowledge of how anti-tumor immunity was generated and regulated in CRC, and provide novel targets for CRC immunotherapies.