Role of the prostaglandin D2 receptor CRTH2 in helminth-induced type 2 inflammation in the intestine

项目摘要 肠道蠕虫寄生虫感染全球数十亿人。哺乳动物宿主携带2型炎性 对感染的反应，其特征在于免疫细胞活化和肠上皮细胞粘液 导致蠕虫排出的分泌物，但也可导致病理性的过量粘液产生。先前 工作集中在宿主来源的蛋白质称为细胞因子如何控制2型炎症，但其他因素 例如脂质前列腺素D2（PGD 2）也在感染期间产生。PGD 2促进2型过敏 通过与CRTH 2（Th 2上表达的化学引诱物受体同源分子）结合导致的肺部炎症 细胞）。然而，PGD 2-CRTH 2通路如何与细胞因子相互作用以调节2型炎症， 肠道蠕虫感染的原因尚不清楚。我们的初步研究显示，感染了 蠕虫Nippostrongylus brasiliensis，CRTH 2缺陷小鼠的2型免疫活化降低 但令人惊讶的是，与对照组相比， 间隙在感染的骨髓嵌合小鼠中也观察到这种表型，其中只有非- 造血细胞缺乏CRTH 2，这表明PGD 2-CRTH 2通路抑制肠上皮细胞 细胞粘液反应。值得注意的是，PGD 2的产生是如何调节的尚不清楚。上皮细胞来源的 细胞因子白细胞介素（IL）-33在蠕虫感染期间激活免疫细胞，促进PGD 2的产生 从肥大细胞中分离出来因此，IL-33可以在体内激活PGD 2-CRTH 2通路。我们的初步研究 表明IL-33治疗后，CRTH 2缺陷小鼠IL-33-的群体扩张受损 与对照组相比，对IL-33的最佳反应是对第2组先天淋巴细胞的反应，这表明， 体内需要CRTH 2。总之，这些数据引发了中心假设，即在蠕虫感染期间，IL-33 激活PGD 2-CRTH 2通路以平衡2型炎症反应，有效驱逐蠕虫 同时限制病理学。为了验证这一假设，我们提出了两个具体目标。目标1将测试PGD 2是否起作用 直接作用于小肠上皮细胞，抑制2型炎症期间粘蛋白的产生，依赖于 CRTH 2，使用小肠类器官培养物和允许CRTH 2缺失的新小鼠模型 只存在于肠上皮细胞中。目的2将测试IL-33如何调节肥大细胞产生PGD 2，以形成 2型炎症期间的免疫应答，使用功能获得和丧失实验，过继转移 方法，以及骨髓嵌合小鼠与N.巴西人感染这些数据将支持 产生蠕虫诱导的2型肠道炎症的新范例， PGD 2和CRTH 2，并将告知靶向PGD 2-CRTH 2途径的药物的开发和使用 治疗与II型炎症相关的疾病。

PROJECT SUMMARY Intestinal helminth parasites infect billions worldwide. Mammalian hosts mount a Type 2 inflammatory response to infection, which is characterized by immune cell activation and intestinal epithelial cell mucus secretion that lead to worm expulsion but can also cause pathological excess mucus production. Previous work has focused on how host-derived proteins called cytokines control Type 2 inflammation, but other factors such as the lipid prostaglandin D2 (PGD2) are also produced during infection. PGD2 promotes Type 2 allergic lung inflammation by binding to CRTH2 (chemoattractant receptor-homologous molecule expressed on Th2 cells). However, how the PGD2-CRTH2 pathway interacts with cytokines to regulate Type 2 inflammation during intestinal helminth infection is unclear. Our preliminary studies revealed that following infection with the helminth Nippostrongylus brasiliensis, CRTH2-deficient mice had decreased Type 2 immune activation compared to controls, but surprisingly also had increased epithelial mucin responses and accelerated worm clearance. This phenotype was also observed in infected bone marrow chimeric mice in which only non- hematopoietic cells lacked CRTH2, suggesting that the PGD2-CRTH2 pathway suppresses intestinal epithelial cell mucus responses. Notably, how PGD2 production is regulated is unclear. The epithelial cell-derived cytokine interleukin (IL)-33, which activates immune cells during helminth infection, elicits PGD2 production from mast cells in vitro. Thus, IL-33 may activate the PGD2-CRTH2 pathway in vivo. Our preliminary studies showed that following IL-33 treatment, CRTH2-deficient mice had impaired population expansion of IL-33- responsive group 2 innate lymphoid cells compared to controls, suggesting that optimal responses to IL-33 in vivo require CRTH2. Together, these data provoke the central hypothesis that during helminth infection, IL-33 activates the PGD2-CRTH2 pathway to balance Type 2 inflammatory responses, expelling worms efficiently while limiting pathology. To test this hypothesis, we propose 2 Specific Aims. Aim 1 will test if PGD2 acts directly on small intestinal epithelial cells to inhibit mucin production during Type 2 inflammation, dependent on CRTH2, using small intestinal organoid cultures and a new mouse model that allows for deletion of CRTH2 only in intestinal epithelial cells. Aim 2 will test how IL-33 regulates PGD2 production by mast cells to shape immune responses during Type 2 inflammation, using gain- and loss-of-function experiments, adoptive transfer approaches, and bone marrow chimeric mice coupled with N. brasiliensis infection. These data will support the generation of a new paradigm of helminth-induced Type 2 intestinal inflammation that incorporates the effects of PGD2 and CRTH2, and will inform the development and use of drugs that target the PGD2-CRTH2 pathway to treat diseases associated with Type 2 inflammation.