Project 1: Inhibition of Complement C5aR1 Radioprotects Normal Tissue and Radiosensitizes Tumors

摘要（项目1-牛津） 增加放射治疗的治疗窗口可以通过使用针对癌症的靶向治疗来实现- 相关路径。补体系统是一种先天免疫途径，在癌症中发挥着重要作用 进展没有研究评估补体抑制对肿瘤和正常组织的影响 辐射反应在这里，我们表明，靶向补体受体C5aR1改善辐射反应， 结直肠癌模型，同时减少辐射诱导的毒性。靶向C5aR1增加IL-10分泌， 其减弱NF-κ B信号传导并增强肿瘤细胞中的凋亡。IL-10依赖性细胞凋亡 在体内和体外均观察到，表明非典型的应激特异性和可能的免疫独立作用 C5aR1在调节细胞凋亡中的作用。重要的是，我们发现C5aR1缺失会导致小肠粘膜上皮细胞减少， 组织损伤、隐窝细胞凋亡和照射后小鼠存活率增加。在小肠中， C5aR1耗竭导致非免疫和免疫细胞群体中IL-10表达增加。IL-10 CX3CR1+巨噬细胞中的信号传导对于肠损伤防御是重要的，C5aR1-/-小鼠具有显著的 CX3CR1+巨噬细胞水平高于WT小鼠。在对辐射的反应中，C5aR1消耗不 减弱NF-κ B信号传导，但相反增加AKT活化，与细胞凋亡发生减少相关 以IL-10依赖的方式。因此，我们的数据表明，以C5aR1基因为靶点的 可以改善结肠直肠肿瘤模型中的辐射反应，同时降低辐射诱导的小肠毒性。 总之，这些发现表明，抑制补体可能是一种有前途的方法，以增加 放疗治疗窗。在这个项目中，我们提出了四个具体目标，以更好地理解的作用， C5aR1在辐射防护和辐射增敏中的作用。目标1将确定对下列各项的广泛保护还是具体保护： C5aR1-/-小鼠的正常上皮细胞（肠、唾液腺和肺上皮细胞） 与项目2、3、4和核心项目B合作，开展大分割放射治疗。在目标2中，我们将研究 当C5aR1被抑制时，辐射防护的机制基础。我们的初步数据表明，这是一个 IL-10依赖性机制，并涉及促进存活的CX3CR1+巨噬细胞的募集， 血管生成目的3将确定C5aR1如何与放射治疗联合促进肿瘤细胞杀伤。 基于我们初步数据的假设是C5aR1抑制增加IL-10分泌， 减弱NF-κ B信号传导，导致细胞培养物和动物中IL-10依赖性肿瘤细胞杀伤 模型目的4将确定临床级C5aR1抑制剂对放射防护肠、唾液和肠上皮细胞的作用。 腺体和肺，并使结肠直肠肿瘤对放射治疗敏感。我打算每月回斯坦福大学 或者每两个月一次，我会和我在斯坦福大学的同事们分享这些数据。在牛津，我们表演我们自己的 将与斯坦福大学的核心B合作，以确保方法的可比性。

Abstract (Project 1 - Oxford) Increasing the therapeutic window of radiotherapy may be achieved by using targeted therapies against cancer- associated pathways. The complement system is an innate immunity pathway, with emerging roles in cancer progression. No study has evaluated the effect of complement inhibition on both tumor and normal tissue radiation response. Here we show that targeting complement receptor C5aR1 improves radiation response in colorectal cancer models while reducing radiation-induced toxicity. Targeting C5aR1 increases IL-10 secretion, which attenuates NF-κB signaling and enhances apoptosis in tumor cells. IL-10-dependent apoptosis is observed both in vivo and in vitro suggesting a non-canonical stress-specific and likely immune-independent role for C5aR1 in regulating apoptosis. Importantly, we find that C5aR1 depletion results in decreased small intestinal histologic damage, crypt cell apoptosis and increased survival of mice following irradiation. In the small intestine, C5aR1 depletion results in increased IL-10 expression in both non-immune and immune cell populations. IL-10 signaling in CX3CR1+ macrophages is important for intestinal injury defense and C5aR1-/- mice have significantly higher levels of CX3CR1+ macrophages than WT mice. In response to irradiation, C5aR1 depletion does not attenuate NF-κB signaling but instead increases AKT activation correlating with decreased apoptosis occurring in an IL-10-depedent manner. Our data, therefore, indicate that genetically or pharmacologically targeting C5aR1 can improve radiation response in colorectal tumor models while reducing radiation-induced small bowel toxicity. Together, these findings suggest that inhibiting complement could be a promising approach to increasing the therapeutic window of radiotherapy. In this Project, we propose four specific aims to better understand the role of C5aR1 in radioprotection and radiosensitization. Aim 1 will determine the broad versus specific protection of normal epithelium (intestines, salivary glands, and lung epithelium) by C5aR1-/- mice in response fractionated and hypofractionated radiotherapy, in collaboration with Projects 2, 3, 4 and Core B. In Aim 2, we will investigate the mechanistic basis of radioprotection when C5aR1 is inhibited. Our preliminary data indicates that this is an IL-10 dependent mechanism and involves recruitment of CX3CR1+ macrophages that promote survival and angiogenesis. Aim 3 will determine how C5aR1 promotes tumor cell killing in combination with radiotherapy. The hypothesis based on our preliminary data is that C5aR1 inhibition increases IL-10 secretion, which attenuates NF-κB signaling, resulting in IL-10 dependent tumor cell killing both in cell culture and in animal models. Aim 4 will determine the effect of clinical grade C5aR1 inhibitors on radioprotecting intestine, salivary glands and lungs, and sensitizing colorectal tumors to radiotherapy. I intend to return to Stanford on a monthly or bimonthly schedule and will share this data with my colleagues at Stanford. At Oxford, we perform our own dosimetry and will cooperate with Core B at Stanford to ensure comparability of methods.