Tracking Mucosal T cells to Commensal Microbes in Vivo

描述：免疫球蛋白抗体提供了对抗粘膜病原体的重要第一道防线。针对T细胞依赖抗原的免疫球蛋白的诱导从属于T细胞激活、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致病微生物群和共生微生物群的蛋白质抗原做出反应。我们目前的目标是在体内确定共生的鼠乳杆菌在肠道中诱导哪种类型的T细胞反应。 我们假设肠道共生微生物通过粘膜诱导T细胞依赖的体液反应，同时抑制细胞介导的反应。通过验证这一假设，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细胞中激发的细胞因子类型来检验这一假设。我们改造小鼠乳杆菌表达一种卵清蛋白表位，当注射到皮下时诱导卵清蛋白特异性T细胞增殖。我们将一小部分卵清蛋白特异性T细胞注射到受体小鼠体内，并大量喂养小鼠。通过用抗CD4和抗T细胞受体单抗对受者的细胞悬液或组织进行染色来追踪卵清蛋白特异的T细胞。四色流式细胞术和共聚焦免疫组织学将在体内建立通过肠道的共生微生物激活T细胞来诱导CD69表达。 以抗原特异性的方式，我们将测试跨粘膜T细胞激活、增殖和分化为产生细胞因子的记忆细胞的表型和动力学。总而言之，这项研究将阐明口服抗原传递和分泌抗体产生之间缺失的联系。这些数据将对人类健康很重要，建立了一个研究活体粘膜感染剂和口服疫苗的框架。

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.