MAINTENANCE OF ORAL TOLERANCE BY CD4+ T CELLS IN VIVO

口服耐受是指对饮食抗原的免疫耐受，是避免肠道内对大量外来抗原产生有害炎症反应的关键机制。饮食抗原也可能是系统刺激T细胞的重要来源，因此可能在塑造外周T细胞的功能表型中发挥作用。口服耐受和外周耐受的机制通常知之甚少，主要是因为直到最近还不可能在体内追踪抗原特异性T细胞。几年前，我们的实验室开发了一种解决这个问题的方法，即开发了DO11.10 TCR转基因CD4+T细胞的过继转移系统。这项建议描述了该系统在使用方面的进一步方法学进展，现在可以直接检查体内抗原刺激后单个抗原特异的CD4+T细胞内的生化活性。使用这些方法，我们想要描述在耐受诱导后体内发现的T细胞的“无能”状态。然而，我们的初步数据表明，耐受性不能简单地归因于抗原特异性T细胞的功能失活，也是“耐受”环境的一种功能。主要使用细胞免疫学技术，我的目标是确定构成这个环境的关键成分。在对CD25+亚群的抗原特异性CD4+细胞的研究中，这两个特定目的之间的边界是模糊的，这些亚群只有在耐受性抗原暴露后才出现，特别是在抗原喂养之后。这些细胞似乎既是“无能的”，也可能是“抑制的”。我相信，在马克·詹金斯博士的指导下，对于我作为一名完全独立的调查员的发展的最后阶段来说，这是一个理想的情况。该实验室继续处于研究体内抗原特异性CD4+T细胞反应的技术前沿。额外的多年指导将是有帮助的，因为我对T细胞反应的详细生物化学的兴趣是相对较新的补充，我过去的研究经验。我认为，将我的培训扩展到尝试从更分子的角度来看待生物学问题，对于成为一名全面的研究人员至关重要。目前的建议大多集中在口服耐受作为系统免疫耐受的一种形式。然而，直接检查肠道内抗原特异性的CD4+T细胞对饮食抗原的反应是这项建议的重要组成部分。这也将是我今后调查的主要方向。归根结底，作为一名学术胃肠病专家，我最感兴趣的是将来自动物研究的概念应用于理解和治疗人类，涉及胃肠道内的免疫失调。

Oral tolerance, a term applied to immunologic tolerance toward dietary antigens, is a critical mechanism for avoiding harmful inflammatory reactions toward numerous foreign antigens in the intestine. Dietary antigens may also be an important source of stimulation for T cells systematically and may therefore play a role in shaping the functional phenotype of peripheral T cells. Mechanisms of oral tolerance, and peripheral tolerance in general are poorly understood primarily because until recently it has been impossible to track antigen-specific T cells in vivo. Several years ago our laboratory has developed one solution to this problem by developing an adoptive transfer system of DO11.10 TCR transgenicCD4+ T cells. This proposal describes further methodological advances in the use of this system that now allow direct examination of biochemical activity within individual antigen-specific CD4+ T cells following antigenic stimulation in vivo. Using these methods we would like to characterize the "anergic" state of T cells found in vivo following tolerance induction. Our preliminary data, however, show that tolerance cannot be simply attributed to functional inactivation of antigen-specific T cells, but is also a function of the "tolerized" environment. Using primarily cellular immunology techniques I aim to identify the critical components of what constitutes this environment. The borders between the two specific aims blur in the study of the CD25+ sub-population of antigen-specific CD4+ cells that arise only following tolerogenic antigen exposure, particularly antigen feeding. These cells appear to be both "anergic" and potentially "suppressive". I believe staying under mentorship of Dr. Marc Jenkins represents an ideal situation for this final stage of my development as a fully independent investigator. This laboratory continues to be at the cutting technical edge of studying antigen-specific CD4+ T cell response in vivo. Additional years of mentorship would be helpful since my interests in detailed biochemistry of T cell responses are a relatively recent addition to my past research experiences. I believe extending my training to include attempts to view biological problems in more molecular terms is critical to becoming a well-rounded researcher. Most of the current proposal centers on oral tolerance as a form of systemic immunologic tolerance. However, direct examination of the antigen-specific CD4+ T cell response toward dietary antigen within the intestine itself is an essential part of this proposal. It will also be the main direction of my future investigations. Ultimately, as an academic gastroenterologist I am most interested in applying concepts derived from animal studies toward understanding and therapy of human involving immune dysregulation within the gastrointestinal tract.