Antigen Processing And Presentation In The Intestine

抗原在肠道中的加工和呈现

• 批准号: 7196645
• 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/7196645
• 关键词: Peyer' s patches; antigen presentation; cell population study; colitis; dendritic cells; disease /disorder model; enzyme linked immunosorbent assay; fluorescence microscopy; genetic regulatory element; genetic susceptibility; immune tolerance /unresponsiveness; in situ hybridization; inflammation; interleukin 10; intestines; laboratory mouse; leukocyte activation /transformation; lymphocyte; mucosal immunity; 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. In prior studies we have established the presence of different antigen-presenting cell populations in the Peyer's patch (PP) and lamina propria and have detailed the surface phenotype, function, and migration of DCs in the PP using in situ immunofluorecense microscopy and in situ hybridization, flow cytometry of purified cells, and in vitro assays of cytokine production (ELISA and quantitative RT-PCR) and T cell differentiation. We determined that there are 3 separate subpopulations of immature DCs in the PP, lymphoid (CD8+), myeloid (CD11b+), and double negative (DN) Dcs that express neither CD8 or CD11b. These separated DC subpopulations are located in distinct sites in the PP, and are capable of inducing the differentiaion of T cells into cells that produce unique cytokine profiles. Most importantly, we demonstrated that PP DCs have the unique capacity to induce the differntiation of T cells that produce high levels of IL-10, a cytokine important for the IgA B cell differentiation. These studies thus are some of the first to directly demonstrate that DCs from different tissues may be unique in their ability to induce tissue specific immunity. We have also recently demonstrated that DN DCs in the subepithelial dome region of the PP process viral antigen from virally infected apoptotic epithelial cells. During the past year we have made several advances, in collaboration with other NIH and outside investigators. 1) We identified a genetic major locus for the susceptibility of colitis in the Gi2a-/- mouse model of intestinal inflammation. This happens to be the same locus identified by others in the IL-10-/- model providing strong evidence that this locus is important. 2) We demonstrated that dendritic cells from germ-free mice are phenotypically and functionally normal. which demonstrates that commensal bacteria are not required for the generation of functionally normal dendritic cells. 3) Demondtrated the lack of a role for TL antigen in the activation of intraepithelial lymphocytes.

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。在之前的研究中，我们已经确定派尔氏淋巴集结 (PP) 和固有层中存在不同的抗原呈递细胞群，并使用原位免疫荧光显微镜和原位杂交、纯化细胞的流式细胞术以及细胞因子产生的体外测定（ELISA 和定量）详细介绍了 PP 中 DC 的表面表型、功能和迁移。 RT-PCR）和T细胞分化。我们确定 PP 中存在 3 个独立的未成熟 DC 亚群，即淋巴 (CD8+)、骨髓 (CD11b+) 和双阴性 (DN) DC，它们既不表达 CD8 也不表达 CD11b。这些分离的 DC 亚群位于 PP 的不同位点，能够诱导 T 细胞分化为产生独特细胞因子谱的细胞。最重要的是，我们证明 PP DC 具有诱导 T 细胞分化的独特能力，可产生高水平的 IL-10（一种对 IgA B 细胞分化很重要的细胞因子）。因此，这些研究首次直接证明来自不同组织的树突状细胞在诱导组织特异性免疫方面可能是独特的。我们最近还证明，PP 上皮下圆顶区域的 DN DC 可以处理来自病毒感染的凋亡上皮细胞的病毒抗原。在过去的一年里，我们与其他 NIH 和外部研究人员合作，取得了一些进展。 1) 我们在 Gi2a-/- 小鼠肠道炎症模型中确定了结肠炎易感性的一个主要遗传位点。这恰好与其他人在 IL-10-/- 模型中鉴定的基因座相同，提供了强有力的证据表明该基因座的重要性。 2）我们证明来自无菌小鼠的树突状细胞表型和功能正常。这表明共生细菌对于生成功能正常的树突状细胞来说不是必需的。 3)证明TL抗原在上皮内淋巴细胞的激活中缺乏作用。