Tracking Mucosal T cells to Commensal Microbes in Vivo

描述：IgA 抗体提供了针对粘膜病原体的重要第一道防线。针对 T 细胞依赖性抗原的免疫球蛋白的诱导服从于 T 细胞活化、T/B 细胞相互作用和细胞因子。我们的长期目标是了解粘膜免疫系统如何对有毒和共生微生物群的蛋白质抗原做出反应。我们当前的目标是确定体内共生鼠乳杆菌在通过肠道时诱导哪种类型的 T 细胞反应。 我们假设肠道共生微生物跨粘膜诱导 T 细胞依赖性体液反应，同时抑制细胞介导的反应。检验这一假设可以设计出有效的微生物输送系统。我们将通过确定 1) 共生微生物如何启动肠道中的幼稚 T 细胞和 2) 记忆 T 细胞中引发的细胞因子类型来检验这一假设。我们对 L. murinus 进行了改造，使其表达卵清蛋白表位，皮下注射时可诱导卵清蛋白特异性 T 细胞增殖。我们将一小群卵清蛋白特异性 T 细胞注射到受体小鼠体内，并喂养大量小鼠乳杆菌。通过用抗 CD4 和抗 T 细胞受体单克隆抗体对受体的细胞悬液或组织进行染色来追踪卵清蛋白特异性 T 细胞。四色流式细胞术和共聚焦免疫组织学将在体内确定穿过肠道的共生微生物激活 T 细胞以诱导 CD69 表达。 我们将以抗原特异性的方式测试跨粘膜 T 细胞活化、增殖和分化为产生细胞因子的记忆细胞的表型和动力学。总的来说，这项研究将阐明口服抗原递送和分泌抗体产生之间缺失的联系。这些数据对人类健康非常重要，建立了研究体内粘膜感染因子和口服疫苗的框架。

DESCRIPTION: IgA antibodies provide an important first line of defense against mucosal pathogens. The induction of immunoglobulins against T cell-dependent antigens is subordinate to T cell activation, T/B cell interaction and cytokines. Our long-range goal is to learn how the mucosal immune system responds to protein antigens of the virulent and commensal microbiota. Our current objective is to determine, in vivo, which type of T cell response is induced by the commensal Lactobacillus murinus, while transiting the intestine. We hypothesize that intestinal commensal microorganisms transmucosally induce a T cell-dependent humoral response, while suppressing the cell-mediated response. Testing this hypothesis can lead to the design of effective microbial delivery systems. We will test this hypothesis by determining 1) how a commensal microbe primes naive T cells in the intestine and 2) the type of cytokines elicited in memory T cells. We engineered L. murinus to expresses an ovalbumin epitope that induces ovalbumin-specific T cell proliferation when injected subcutaneously. We inject a small population of ovalbumin-specific T cells into recipient mice and feed L. murinus in high numbers. Ovalbumin-specific T cells are tracked by staining cell suspensions or tissues of the recipients with anti-CD4 and an anti-T cell receptor monoclonal antibody. Four-color flow cytometry and confocal immunohistology will establish in vivo that commensal microorganisms transiting the intestine activate T cells to induce CD69 expression. In an antigen-specific manner we will test the phenotype and kinetics of transmucosal T cell activation, proliferation and differentiation into cytokine-producing memory cells. Collectively, this research will elucidate the missing link between the oral antigen delivery and the production of secretory antibodies. The data will be important to human health, establishing a framework to study in vivo mucosal infectious agents and oral vaccines.