Specialization of Innate and Adaptive Immune Cells in Intestinal Barrier Function

项目摘要 先天性和适应性免疫细胞在肠屏障功能中的特化。维护 粘膜屏障完整性需要先天性和适应性免疫细胞与粘膜上皮的相互作用。 白细胞介素-22（IL-22）是IL-10家族的细胞因子，其由3型免疫细胞（如3型免疫细胞）产生， 先天性淋巴样细胞（ILC 3）和Th 17途径的细胞，并作用于屏障组织的上皮细胞， 防止某些微生物的入侵，特别是细胞外细菌和真菌。保护的基础 IL-22对肠上皮细胞（IEC）的作用尚不完全清楚，但它可以增强其产生 抗微生物因子，维持上皮紧密连接并促进IEC的增殖和存活。 与许多参与宿主防御的免疫细胞因子一样，IL-22在慢性免疫介导的炎症反应中上调。 它似乎在炎症性肠病（IBD）中发挥保护作用，可能是通过抑制 T细胞对肠道成分的反应失调引起的上皮损伤 微生物组然而，IL-22的过度增殖作用也涉及上皮恶性肿瘤， 大肠癌（CRC）是一种恶性肿瘤。我们和其他人已经证明，在感染性结肠炎期间， 以肠道病原体C.在啮齿类动物中，IL-22的产生可以分为两个阶段： 由产生IL-22的先天免疫细胞主导的晚期阶段，以及由产生IL-22的先天免疫细胞主导的晚期阶段。 产生CD 4 T细胞。虽然先天性和适应性免疫细胞在感染过程中都会产生IL-22，但它们的 对宿主保护的相对贡献是未知的，IL-22作用机制的细节也是未知的。在 在初步研究中，我们已经产生了新的IL-22报告基因/条件性敲除（cKO）小鼠， 追踪和/或删除产生IL-22的免疫细胞的特定亚群。值得注意的是，我们发现 IL-22产生细胞在C.啮齿类感染是不同的：先天免疫细胞， 主要由ILC 3控制，主要定位于孤立的淋巴滤泡，并在起始部位激活浅表IEC 细菌的殖民。然而，ILC 3不能保护肠隐窝，肠隐窝被细菌侵入， IL-22缺陷小鼠靶向T细胞。因此，产生IL-22的T细胞似乎是不可或缺的， 通过激活肠隐窝衬里上皮保护肠隐窝。我们假设IL-22- 产生先天性细胞限于在细菌附着的初始位点快速激活表面IEC， 而产生IL-22的T细胞是防止细菌侵入隐窝所必需的。此外，表面和 隐窝IEC对IL-22依赖性先天和适应性信号的反应不同。在本提案中，我们将 定义先天性和适应性免疫细胞对IL-22依赖性激活不同免疫细胞的相对贡献。 结肠上皮细胞的亚群，并定义了IL-22诱导的基因表达程序， 先天性或适应性免疫细胞作用。这些研究将揭示新的见解专业化的免疫 肠宿主防御中的细胞亚群和控制IBD和CRC中肠道炎症的机制。

PROJECT SUMMARY Specialization of Innate and Adaptive Immune Cells in Intestinal Barrier Function. Maintenance of mucosal barrier integrity requires the interplay of innate and adaptive immune cells with the mucosal epithelium. Interleukin-22 (IL-22) is a cytokine of the IL-10 family that is produced by type 3 immune cells, such as group 3 innate lymphoid cells (ILC3s) and cells of the Th17 pathway, and acts on epithelial cells of barrier tissues to prevent invasion of certain microbes, particularly extracellular bacteria and fungi. The basis for the protective actions of IL-22 on intestinal epithelial cells (IECs) is not fully understood, but it enhances their production of antimicrobial factors, maintains epithelial tight junctions and promotes the proliferation and survival of IECs. Like many immune cytokines that participate in host defense, IL-22 is upregulated in chronic immune-mediated diseases, and it appears to play a protective role in inflammatory bowel disease (IBD), perhaps by restraining the epithelial damage caused by dysregulated T cell responses against constituents of the intestinal microbiome. However, the hyperproliferative effects of IL-22 have also been implicated in epithelial malignant transformation that leads to colorectal cancer (CRC). We and others have shown that during infectious colitis modeled by the enteropathogen, C. rodentium, two phases of IL-22 production can be distinguished: an early phase dominated by IL-22–producing innate immune cells, and a late phase that is dominated by IL-22– producing CD4 T cells. While both innate and adaptive immune cells produce IL-22 during infection, their relative contributions to host protection are unknown, as are details of the mechanisms by which IL-22 acts. In preliminary studies, we have generated novel IL-22 reporter/conditional knockout (cKO) mice with which to track and/or delete specific subsets of IL-22-producing immune cells. Remarkably, we find that the locations and functions of IL-22–producing cells during C. rodentium infection are distinct: innate immune cells, dominated by ILC3s, localize primarily to isolated lymphoid follicles and activate superficial IECs at initial sites of bacterial colonization. However, ILC3s fail to protect the intestinal crypts, which are invaded by bacteria in mice with IL-22 deficiency targeted to T cells. Thus, IL-22–producing T cells appear to be indispensible for protection of the intestinal crypts via their activation of crypt-lining epithelium. We hypothesize that IL-22– producing innate cells are limited to rapid activation of superficial IECs at initial sites of bacterial attachment, whereas IL-22–producing T cells are required to prevent bacterial invasion of crypts. Moreover, superficial and crypt IECs differ in their response to IL-22-dependent innate and adaptive signals. In this proposal we will define the relative contributions of innate and adaptive immune cells to IL-22–dependent activation of different subsets of colonic epithelial cells, and define the gene expression programs elicited by IL-22 in the context of innate or adaptive immune cell actions. These studies will reveal new insights into specialization of immune cell subsets in intestinal host defense and mechanisms that control intestinal inflammation in IBD and CRC.