ANTIGEN PROCESSING AND PRESENTATION IN THE INTESTINE

抗原在肠道中的加工和呈递

• 批准号: 6289008
• 负责人: BRIAN KELSALL
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6289008
• 关键词: Peyer's patches; T lymphocyte; antigen presentation; cell differentiation; cholera toxin; cytokine; dendritic cells; flow cytometry; immunomodulators; intestines; laboratory mouse; mucosal immunity; oral tolerance; polymerase chain reaction

This project focuses on how antigens are processed in the intestine of mice. While it is clear that the outcome of oral antigen exposure can be either positive, i.e., the development of mucosal IgA responses, and in some cases the induction of systemic immunity as well, or negative, i.e., the induction of oral tolerance, the details of why one or the other outcome occurs is complex and poorly understood. While it is known that the antigen formulation, the presence of adjuvants, and the antigen dose, as well as genetic factors, can affect mucosal immune responses, how these act to influence immunity has never been established. Prior studies have established the presence of different antigen-presenting cell populations in the Peyer?s patch and lamina propria of the intestine. We have described the presence of at least two populations of dendritic cells (DCs) in the Peyer?s patch, which is the primary inductive site for mucosal immune responses. One population of DCs appears to be immature and poised for capture of antigens transported from the intestinal lumen into the Peyer?s patch as it is present in a dense layer just beneath the intestinal epithelium overlying the Peyer?s patch follicle in a region referred to as the subepithelial dome (SED). A second population of more mature cells is present in the major T cell regions of the Peyer?s patch, the interfollicular regions (IFR). These findings suggest that oral antigens are taken up by immature DCs and following migration and differentiation (or activation), these cells present antigens to T cells in the IFR. Another possibility is that such antigen-loaded DCs migrate to draining mesenteric lymph nodes where they act to induce primary T cell responses. A third population of DCs appears to be of the less mature phenotype and is present in the B cell follicles of the Peyer?s patch. How these different DCs act to present intestinal antigens is the focus of this project. The studies will entail the isolation and further characterization of DCs from the Peyer?s patch, mesenteric lymph nodes, and lamina propria. This will involve studies of surface phenotype by flow cytometry, cytokine production by RT-PCR or isolated and stimulated cells, and the ability to induce T cell differentiation in vivo. Finally, the ability of mucosal adjuvants such as cholera toxin, and different immunization regimens to affect DC antigen presentation, will be explored. Findings with DCs will be compared to antigen loading and phenotypic changes in other antigen presenting cell populations, such as B cells and monocyte/macrophages from intestinal lymphoid tissue. - dendritic cell, Peyer?s patch, mucosal immunity, Th1, Th2, lymphcyte, cytokine, antigen presenting cell, immunology, chemokine

该项目重点研究抗原如何在小鼠肠道中加工。虽然很明显，口服抗原暴露的结果可以是阳性的，即产生粘膜 IgA 反应，并且在某些情况下还诱导全身免疫，也可以是阴性的，即诱导口服耐受，但为什么发生一种或另一种结果的细节是复杂的且知之甚少。虽然已知抗原配方、佐剂的存在、抗原剂量以及遗传因素可以影响粘膜免疫反应，但这些如何影响免疫反应尚未确定。先前的研究已经证实在派尔氏淋巴结和肠道固有层中存在不同的抗原呈递细胞群。我们已经描述了派尔氏淋巴结中至少存在两个树突状细胞（DC）群体，这是粘膜免疫反应的主要诱导位点。一组 DC 似乎不成熟，准备捕获从肠腔转运到派尔氏集结区的抗原，因为它存在于肠上皮正下方的致密层中，覆盖在称为上皮下圆顶 (SED) 的区域中的派尔氏集结滤泡上。第二群更成熟的细胞存在于派尔氏淋巴结的主要 T 细胞区域，即滤泡间区域 (IFR)。这些发现表明，口腔抗原被未成熟的 DC 吸收，并在迁移和分化（或激活）后，这些细胞将抗原呈递给 IFR 中的 T 细胞。另一种可能性是，这种负载抗原的 DC 迁移到引流肠系膜淋巴结，在那里它们诱导初级 T 细胞反应。第三种 DC 群体似乎具有不太成熟的表型，存在于派尔氏集结的 B 细胞滤泡中。这些不同的树突状细胞如何发挥作用来呈递肠道抗原是该项目的重点。这些研究将需要从派尔氏集结、肠系膜淋巴结和固有层中分离和进一步表征 DC。这将涉及通过流式细胞术研究表面表型、通过 RT-PCR 或分离和刺激细胞研究细胞因子的产生，以及体内诱导 T 细胞分化的能力。最后，将探讨霍乱毒素等粘膜佐剂和不同免疫方案影响 DC 抗原呈递的能力。 DC 的发现将与其他抗原呈递细胞群（例如来自肠道淋巴组织的 B 细胞和单核细胞/巨噬细胞）的抗原负载和表型变化进行比较。 - 树突状细胞、派尔氏集结、粘膜免疫、Th1、Th2、淋巴细胞、细胞因子、抗原呈递细胞、免疫学、趋化因子