DEVELOPMENT AND FUNCTION OF INTESTINAL T-CELLS

胃肠道是许多细菌、寄生虫、真菌和病毒病原体的入口，也是健康和免疫受损宿主感染的重要部位。宿主使用一种由体液和细胞成分组成的精心设计的特定免疫系统来保持小肠的完整性，以抵御微生物的入侵。特异性黏膜免疫反应的体液臂主要由IgA抗体的分泌控制，但特异性黏膜免疫的细胞臂的大部分功能潜力尚不清楚。我们将利用小鼠实验性呼肠孤病毒感染来剖析肠道T细胞在粘膜免疫反应中的功能。本提案描述了一项实现三个具体目标的计划，这些目标是根据上一个供资期间提出和报告的意见制定的。这一建议的中心假设是，肠道感染引起不同的肠道T细胞群，这些T细胞调节局部和系统免疫反应的发展。在目标1中，我们将通过检测口服或系统感染呼肠孤病毒的小鼠的免疫球蛋白亚类和细胞因子反应来检验感染途径影响T辅助细胞反应发展的假设，并将这些反应与肠道细菌感染和非肠道病毒感染的小鼠进行比较。在目标2中，我们将验证CD8+T细胞调节粘膜对呼肠孤病毒感染的免疫反应的假设。我们将继续研究CD8缺陷小鼠对肠道病毒感染的免疫反应，并检测过继转移的CD8+T细胞调节CD8缺陷小鼠粘膜免疫反应的能力。在目标3中，我们将检验感染途径影响细胞毒性T淋巴细胞(CTL)上表达的T细胞受体(TCR)谱系的假设。我们将通过使用Vbeta和CDR3分析来分析口腔或全身感染后产生的CTL上TCR的表达。这项工作将有助于理解粘膜免疫在发病机制中的作用，特别是关于T细胞在肠道中的功能。了解肠道T细胞和细胞免疫的发育和功能将为合理设计口服疫苗提供信息，这些疫苗可以靶向肠道免疫效应器的适当反应，特别是针对细胞内病原体。

The gastrointestinal tract serves as a portal of entry for many bacterial, parasitic, fungal, and viral pathogens, and is a significant site of infection in healthy and immunocompromised hosts. An elaborate specific immune system consisting of both humoral and cellular components is used by the host to maintain the integrity of the small intestine against microbial invasion. The humoral arm of the specific mucosal immune response is dominated by secretion of IgA antibodies, but much of the functional potential of the cellular arm of specific mucosal immunity is poorly understood. We will use experimental reovirus infection in mice to dissect the function of intestinal T cells during a mucosal immune response. This proposal describes a plan to accomplish 3 specific aims that are developed from observations made and reported in the previous funding period. The central hypothesis of this proposal is that enteric infection elicits distinct populations of intestinal T-cells that regulate the development of local and systemic immune responses. In aim 1, we will test the hypothesis that the route of infection affects the development of T-helper cell responses by examining IgG subclass and cytokine responses in mice orally or systemically infected with reovirus, and compare these responses to mice infected with enteric bacteria and non-enteric virus. In aim 2, we will test the hypothesis that CD8+ T cells regulate the mucosal immune response to reovirus infection. We will continue to characterize immune responses to enteric virus infection in CD8-deficient mice, and examine the ability of adoptively transferred CD8+ T-cells to regulate mucosal immune responses in CD8-deficient mice. In aim 3, we will test the hypothesis that the route of infection affects the repertoire of T cell receptors (TCR) expressed on cytotoxic T lymphocytes (CTL). We will by analyze TCR expression on CTL that are generated following oral or systemic infection using Vbeta and CDR3 analysis. This work will contribute to understanding mucosal immunity in pathogenesis, particularly with regards to T cell function in the gut. Understanding the development and function of intestinal T-cells and cellular immunity in the gut will provide information that can be used for the rational design of oral vaccines that can target appropriate responses by immunologic effectors in the intestine, particularly against intracellular pathogens.