Role of the complement C3a receptor on immune and non immune intestinal barrier functions and microbiota in colorectal cancer development

虽然最初认为只有少数结直肠癌是由炎症引起的，但研究表明 抗炎药物治疗可预防或延缓遗传性和非遗传性结直肠癌的发展 散发性病例，明确指出炎症是所有类型肺癌发生和发展的关键驱动因素 CRC。然而，目前仍不清楚在复杂的肠道环境中，是什么机制导致了 启动结直肠癌的炎症通路的激活。 肠道在宿主保护和控制过度炎症之间保持着微妙的平衡，我们 假设肠道上皮细胞和免疫成分之间的通讯失调 屏障可能与亚急性炎症状态和CRC的启动有关。补充性系统正在成为 胃肠道中的一个重要角色。具体地说，补体过敏毒素C3a及其受体， C3aR，调节肠道的免疫和上皮室，发挥抗菌作用。通过 挖掘公开可用的数据集，我们发现C3aR在结直肠癌患者中下调，而且事实是 这种下调已经发生在1期肿瘤中，提示这可能是结直肠癌发生的早期事件。 发展。通过将C3aR-/-小鼠与携带APC基因突变的APCMin/+小鼠杂交，类似地 对于大多数人类结直肠癌，我们发现C3aR在结直肠癌中是保护性的。事实上，在APCMin/+小鼠肿瘤中 主要发生在小肠，在APCMin/+/C3aR-/-小鼠中，肿瘤的发生几乎发生了戏剧性的变化 仅限于结肠。我们还发现，缺乏肠道屏障的小鼠存在肠道屏障功能障碍和微生物失调 C3aR，提示C3aR可能是肠道动态平衡的一种新的守门人。不过，目前 未知C3aR如何为CRC的发展做出贡献。 我们假设C3aR的缺失通过影响肠屏障之间的沟通而导致肠屏障功能障碍。 上皮细胞和免疫细胞。这就导致了微生物群驱动的炎症免疫的发展。 促进儿童权利中心发展的对策。为了检验这一假设，我们提出： 1)探讨C3aR缺失对肠屏障上皮成分的影响 与免疫细胞沟通；2)研究C3aR对免疫、非免疫细胞的作用 3)研究人类侵袭前病变中的C3aR状态 和CRC。骨髓嵌合体结合免疫浸润的单细胞高维分析 使用质量细胞术和REAPSEQ将确定C3aR对免疫和非免疫细胞的贡献 与结肠炎和结直肠癌的发生发展有关。我们将评估C3aR下调如何影响 人类结直肠癌和存活率通过使用来自我们特征很好的患者队列的人类标本。作为损失的 C3aR代表结直肠癌早期事件，确定C3aR丢失与发育有关的机制 对CRC的研究不仅将加深我们对CRC的认识，而且对于CRC的预防具有重要意义。

While it was initially believed that only a minority of CRC are driven by inflammation, studies showing that treatment with anti-inflammatory medications may prevent or delay the development of CRC in hereditary and sporadic cases, clearly identify inflammation as a key driver in the development and progression of all types of CRC. Yet, it is still unclear what are the mechanisms that in the complex intestinal environment contribute to the activation of the inflammatory pathways that initiate CRC. The intestine holds a delicate balance between host protection and control of excessive inflammation, and we posit that a dysregulated communication between the epithelial and the immune component of the intestinal barrier may link a sub-acute state of inflammation and CRC initiation. The complement system is emerging as an important player in the gastrointestinal tract. Specifically, the complement anaphylatoxin C3a and its receptor, C3aR, regulate the immune and epithelial compartments in the intestine and exert antibacterial properties. By mining publicly available datasets, we found that C3aR is down-regulated in patients with CRC and the fact that this down-regulation occurs already in stage 1 tumors, suggests that it may be an early event during CRC development. By crossing C3aR-/- mice with the APCMin/+ mice, that carry a mutation in the apc gene, similarly to the majority of human CRC, we showed that C3aR is protective in CRC. Indeed, while in APCMin/+ mice tumors mostly developed in the small intestine, in APCMin/+/C3aR-/- mice tumorigenesis dramatically shifted almost exclusively to the colon. We also found intestinal barrier dysfunction and microbial dysbiosis in mice lacking C3aR, suggesting that C3aR may be a novel gatekeeper in intestinal homeostasis. However, it is currently unknown how C3aR contributes to CRC development. We hypothesize that loss of C3aR causes intestinal barrier dysfunction by affecting the communication between epithelial and immune cells. This then leads to development of microbiota-driven inflammatory immune responses that promote the development of CRC. To test this hypothesis we propose: 1) to investigate how loss of C3aR affects the epithelial component of the intestinal barrier and the communication with the immune cells; 2) To investigate the contribution of C3aR on immune, non immune cell types, and microbiota to CRC development; 3) To investigate the C3aR status in human pre-invasive lesions and CRC. Bone marrow chimera in combination with single cell high dimensional analysis of immune infiltrates using mass cytometry and REAPseq will determine the contribution of C3aR on immune and non immune cells to colon inflammation and CRC development and progression. We will assess how C3aR down-regulation affects human CRC and survival by using human specimens from our well characterized patient cohorts. As loss of C3aR represents an early event during CRC, identifying the mechanisms linking loss of C3aR to the development of CRC will not only further our understanding of CRC but is highly significant for the prevention of CRC.