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

项目总结 肠道寄生虫感染全球数十亿人。哺乳动物宿主产生II型炎症 对感染的反应，其特征是免疫细胞激活和肠道上皮细胞粘液 导致蠕虫排出的分泌物，但也会导致病理性的过量粘液产生。上一首 研究的重点是宿主衍生的称为细胞因子的蛋白质如何控制II型炎症，但其他因素 如脂质前列腺素D2(PGD2)也在感染过程中产生。前列腺素D2促进2型过敏 与CRTH2(Th2上表达的趋化受体同源分子)结合引起的肺部炎症 单元格)。然而，PGD2-CRTH2通路如何与细胞因子相互作用调节II型炎症 肠道蠕虫感染期间尚不清楚。我们的初步研究显示，感染该病毒后 巴西尼波斯特菌、CRTH2缺陷小鼠的2型免疫活性降低 与对照组相比，但令人惊讶的是，还增加了上皮粘蛋白反应和加速蠕虫 通行证。在感染的骨髓嵌合小鼠中也观察到这种表型，在这些小鼠中，只有非 造血细胞缺乏CRTH2，提示PGD2-CRTH2途径抑制肠上皮细胞 细胞粘液反应。值得注意的是，PGD2的生产是如何受到监管的尚不清楚。上皮细胞来源 在蠕虫感染过程中激活免疫细胞的细胞因子IL-33诱导PGD2的产生 来自肥大细胞的体外培养。因此，IL-33可能在体内激活了PGD2-CRTH2途径。我们的初步研究 结果表明，在IL-33治疗后，CRTH2缺陷小鼠抑制了IL-33的种群扩张。 反应性组2与对照组相比，提示对IL-33的最佳反应 VIVO需要CRTH2。总而言之，这些数据引发了一个中心假设，即在蠕虫感染期间，IL-33 激活PGD2-CRTH2途径以平衡2型炎症反应，有效地驱除蠕虫 同时限制病理学。为了检验这一假设，我们提出了两个具体目标。目标1将测试PGD2是否起作用 在2型炎症期间直接依靠小肠上皮细胞抑制粘蛋白的产生，依赖于 CRTH2，使用小肠器官培养和一种允许缺失CRTH2的新小鼠模型 仅存在于肠道上皮细胞中。Aim 2将测试IL-33如何调节肥大细胞产生PGD2以形成 II型炎症期间的免疫反应，使用功能获得和丧失实验，过继转移 方法，和骨髓嵌合体小鼠与巴西奈瑟氏菌感染。这些数据将支持 一种新的蠕虫诱导的2型肠道炎症模型的产生 并将为针对PGD2-CRTH2途径的药物的开发和使用提供信息 用于治疗与2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.