Coordination of T cell-derived signals in intestinal epithelial barrier defense

项目摘要 尽管在上个世纪在治疗和预防疟疾方面取得了很大进展， 发展中国家仍然受到疟疾病原体的困扰，幼儿特别容易受到感染 与埃塞俄比亚有关的死亡长期目标是更好地了解两者的协调反应 免疫和非免疫细胞在肠道感染期间有助于肠道屏障保护。我们集团 最近发现，Th 17/22细胞具有独特的保护肠隐窝免受肠毒性的作用， 病原体;然而，这些T细胞被招募并维持隐窝激活的机制 肠上皮细胞（cIEC）是未知的。本申请的总体目标是（i）阐明本发明的实施例。 参与募集T细胞到cIEC的分子机制和（ii）决定募集的T细胞如何相互作用 与cIEC一起传递保护性IL-22信号。中心假设是IFN γ诱导的IEC-1表达上调， 衍生的T细胞募集趋化因子和MHCII表达促进T细胞募集至结肠隐窝， 分别将病原体特异性T细胞衍生的IL-22信号靶向cIEC。该项目的基本原理是， 参与IL-22向IEC的募集和局部递送的分子将可能产生新的靶点， 由于对肠道病原体的反应， IBD病因学共享重叠的免疫机制。中心假设将通过以下两个方面进行检验： 具体目的：1）Lgr 5 + IEC中的IFN γ信号传导对于募集宿主保护性Cxcr 3 + Th 1和Th 17/22至关重要 2）病原体特异性T细胞通过MHCII依赖性， 持续向IEC递送IL-22。感染性结肠炎的啮齿类柠檬酸杆菌（C.r）模型， 人E.大肠杆菌感染，将被用来测试这两个目标在这个建议。在目标I中，IFN γ R1缺失的小鼠 在Lgr 5 + IEC中的IFN γ信号传导将用于检验Lgr 5 + IEC中IFN γ信号传导是上调所需的假设 T细胞募集趋化因子Cxc 19和Cxc 110以及Cxcr 3缺陷型T细胞的过继转移将用于 确定Cxcl 9/10-Cxcr 3轴是否参与将CD 4 + T细胞募集至cIEC。在Aim II中， IEC上的MHCII表达将用于检测IEC对IL-22- 1抗原呈递的需求。 介导的肠隐窝保护。此外，报告TCR刺激和过继转移的小鼠 的C. r特异性T细胞将用于检验抗原特异性T细胞-IEC相互作用是重要的这一假设 以防止C.r感染。本申请中提出的研究是创新的，因为它利用了 新工程C.r菌株追踪结肠中的抗原特异性T细胞，它提供了独特的见解， LGR 5+肠干细胞的作用以前未被认识。这项拟议的研究意义重大，因为它是 预期提供新的机制，通过该机制，T细胞和IEC合作保护宿主免受肠道感染。 病原体最终，这些知识有可能成为感染性结肠炎和IBD的创新疗法。

PROJECT SUMMARY Although much progress has been made in the treatment and prevention of diarrheal illness over the last century, the developing world is still plagued by diarrheal pathogens, with young children being particularly susceptible to diarrhea-related deaths. The long-term goal is to better understand how the coordinated responses of both immune and non-immune cells contribute to intestinal barrier protection during enteric infection. Our group recently discovered that Th17/22 cells are uniquely charged with protection of the intestinal crypts from enteric pathogens; however, the mechanisms by which these T cells are recruited to and sustain activation of crypt intestinal epithelial cells (cIECs) are unknown. The overall objectives in this application are to (i) elucidate the molecular mechanisms involved in recruiting T cells to cIECs and (ii) determine how recruited T cells interact with cIECs to deliver protective IL-22 signals. The central hypothesis is that IFN–induced upregulation of IEC- derived T cell-recruiting chemokines and MHCII expression promotes T cell recruitment to colonic crypts and targets pathogen-specific T cell-derived IL-22 signals to cIECs, respectively. The rationale for this project is that molecules involved in both recruitment and localized delivery of IL-22 to IECs will likely yield novel targets for therapies in diarrheal illnesses and inflammatory bowel disease (IBD), since responses to enteric pathogens and etiology of IBD share overlapping immune mechanisms. The central hypothesis will be tested by pursuing two specific aims: 1) IFN signaling in Lgr5+ IECs is critical for recruiting host-protective Cxcr3+ Th1 and Th17/22 cells to the colonic crypts; and 2) pathogen-specific T cells protect intestinal crypts via MHCII-dependent, sustained IL-22 delivery to IECs. The Citrobacter rodentium (C.r) model of infectious colitis, which closely models human E. coli infections, will be used to test both aims in this proposal. In Aim I, mice with deletion of the IFNR1 in Lgr5+ IECs will be used to to test the hypothesis that IFN signaling in Lgr5+ IECs is required for upregulation of T cell-recruiting chemokines Cxcl9 and Cxcl10 and adoptive transfer of Cxcr3-deficient T cells will be used to determine if the Cxcl9/10-Cxcr3 axis is involved in recruiting CD4+ T cells to cIECs. In Aim II, mice deficient for MHCII expression on IECs will be utilized to test the requirement of antigen presentation by IECs for IL-22- mediated protection of the intestinal crypts. In addition, mice that report TCR stimulation and adoptive transfer of C.r-specific T cells will be used to test the hypothesis that antigen-specific T cell–IEC interactions are important for protection from C.r infection. The research proposed in this application is innovative because it utilizes a newly engineered C.r strain to track antigen-specific T cells in the colon, and it offers unique insights into previously unrecognized roles of Lgr5+ intestinal stem cells. The proposed research is significant because it is expected to provide novel mechanisms by which T cells and IECs cooperate to protect the host from enteric pathogens. Ultimately, such knowledge has the potential for innovative therapies for infectious colitis and IBD.