Regulation of CD4+ T cells in Cryptosporidium infection

项目摘要 隐孢子虫是引起免疫功能低下患者腹泻和死亡的主要原因 个人和全球营养不良的儿童。隐孢子虫的控制需要CD 4 + T细胞， 细胞因子干扰素-γ（IFN-γ），然而，我们对T细胞调节的理解存在重大差距 对寄生虫的反应。这在很大程度上是由于难以分析肠道中的T细胞群。 通过设计隐孢子虫表达MHCII限制性模型抗原，我可以识别寄生虫特异性抗原。 肠道内的CD 4 + T细胞。使用这个系统，我发现CD 4 + T细胞反应需要1型 传统的树突状细胞（cDC 1），尽管它们在CD 8 + T细胞而不是CD 4 + T细胞中的作用得到了更好的研究 应答此外，我还发现了感染引起的Th 17应答的证据，指出IFN-γ-γ是Th 17应答的一种。 独立但依赖于T细胞的寄生虫控制机制仍然难以捉摸。我会利用 新的转基因寄生虫，遗传小鼠模型，单细胞RNA测序和高- 三维流式细胞术，以测试CD 4 + T细胞应答所需的cDC亚群， 隐孢子虫（SA 1），并研究IFN-γ非依赖性，CD 4 + T细胞依赖性机制， 对照，重点是Th 17应答（SA 2）。这些研究将提供一个机会，在交叉培训- 寄生虫学和免疫学的学科方法，以更好地了解如何免疫感染， 肠道是受调节的。这里提出的研究将影响我们对粘膜的基本理解。 是儿童死亡一个重要原因。

Project Summary The apicomplexan parasite Cryptosporidium is a leading cause of diarrhea and death in immunocompromised individuals and malnourished children globally. Control of Cryptosporidium requires CD4+ T cells and the cytokine interferon-γ (IFN-γ), however there are significant gaps in our understanding of the regulation of T cell responses against the parasite. This is in large part due to difficulties analyzing T cell populations in the gut. By engineering Cryptosporidium to express MHCII-restricted model antigens, I can identify parasite-specific CD4+ T cells within the gut. Using this system, I have found that CD4+ T cell responses require type 1 conventional dendritic cells (cDC1s) despite their better-studied role in CD8+ rather than CD4+ T cell responses. In addition, I have found evidence for a Th17 response elicited by infection, pointing to an IFN-γ- independent but T cell-dependent mechanism of control of the parasite that has remained elusive. I will utilize a combination of novel transgenic parasites, genetic mouse models, single-cell RNA sequencing, and high- dimensional flow cytometry to test which cDC subset(s) are required for CD4+ T cell responses to Cryptosporidium (SA1), and to investigate the IFN-γ-independent, CD4+ T cell-dependent mechanism(s) of control with a focus on Th17 responses (SA2). These studies will provide an opportunity to train in cross- disciplinary approaches in parasitology and immunology to better understand how immunity to infection in the gut is regulated. The studies proposed here will impact our fundamental understanding of mucosal immunology and drive treatment and prevention for an important source of childhood mortality.