Gut mucosal immunity to HIV-1 in controlled and progressive infection

描述(申请人提供)：对艾滋病毒的免疫反应在很大程度上是在最容易接近的隔间-外周血液中进行的研究，它只包含所有淋巴细胞的2%-3%。相比之下，体内至少有一半的T细胞存在于肠道相关淋巴组织(GalT)中。在感染早期，肠粘膜中的CD4+T细胞迅速而严重地耗尽，这些细胞在外周循环中得到显着保存。开始抗逆转录病毒治疗通常会导致病毒载量的抑制和外周CD4+T细胞计数的恢复，但CD4+T细胞在肠道中的重新聚集是相当延迟和不完整的。这些发现表明，肠道代表着一个独特的隔离病毒利基。然而，肠道中艾滋病毒特异性T细胞的功能特征仍然不完整，特别是在“艾滋病毒控制者”中--在没有抗逆转录病毒治疗的情况下自发控制感染的人。在这项应用中，我建议使用新的、最先进的功能分析方法来研究慢性进行性和可控HIV感染患者的肠道CD8+T细胞的功能反应，这将允许对单个细胞进行多参数表征。我假设HIV特异性CD8+T细胞的功能在慢性进行性感染中受损，但在受控感染中保持不变，HIV感染时的免疫功能障碍部分是由于HIV介导的正常肠道屏障的破坏以及肠道树突状细胞的改变。具体地说，我认为肠内皮细胞上存在的黏附连接蛋白E-cadherin通过与HIV特异性CD8+T细胞上的抑制性受体KLRG1结合来介导CTL损伤。此外，我假设肠道树突状细胞损害了HIV介导的Toll样受体(TLR)信号，从而导致慢性进行性感染患者T细胞归巢到小肠的功能障碍。在这一应用中，我打算：1.利用细胞因子分泌和T细胞杀伤的新方法，确定进行性和控制性感染患者肠道内HIV特异性CD8+T细胞的频率和功能；2.通过评估E-钙粘素与HIV特异性CD8+T细胞上抑制受体KLRG1结合的影响，确定肠道微环境在T细胞损伤中的作用；3.研究HIV编码的TLR配体在肠道DC产生维甲酸中的作用以及维甲酸对T细胞肠道归巢受体表达的影响。 相关性(见说明)：人体的大部分免疫细胞驻留在胃肠道，这一区域在艾滋病毒感染期间非常活跃。然而，人类免疫缺陷病毒对肠道的影响仍未完全被研究。我们正在开发新的、最先进的技术，以更好地评估进行性艾滋病毒疾病患者和能够在不使用药物的情况下控制感染的独特个人的肠道免疫系统。这些研究将提供有助于开发更有效的艾滋病毒治疗和疫苗的见解。

DESCRIPTION (provided by applicant): The immune response to HIV has largely been studied in the most accessible compartment - the peripheral blood, which contains only 2-3% of all lymphocytes. In contrast, at least half of the body's T cells reside in gut associated lymphoid tissue (GALT). Early in infection there is a rapid and profound depletion of CD4+ T cells in the intestinal mucosa with notable preservation of these cells in the peripheral circulation. Initiation of antiretroviral therapy typically results in the suppression of viral load and restoration of CD4+ T cells counts in the periphery, but the repopulation of CD4+ T cells in the gut is considerably delayed and incomplete. These findings suggest that the gut represents a unique sequestered viral niche. The functional characterization of HIV specific T cells in the gut, however, remains incomplete, particularly in "HIV controllers" - individuals who spontaneously control infection in the absence of antiretroviral therapy. In this application I propose to study the functional responses of intestinal CD8+ T cells from individuals with chronic progressive and controlled HIV infection using novel, state-of-the-art functional assays that will allow the multiparametric characterization of single cells. I hypothesize that the function of HIV specific CD8+ T cells is impaired in chronic progressive infection but preserved in controlled infection and that immune dysfunction in HIV infection is in part a consequence of HIV mediated disruption of the normal intestinal barrier, as well as alterations in intestinal dendritic cells. Specifically, I propose that E-cadherin, an adherens junction protein present on gut endothelial cells, mediates CTL impairment by binding to the inhibitory receptor KLRG1 on HIV specific CD8+ T cells. Additionally, I hypothesize that intestinal DCs have impaired HIV mediated Toll-like receptor (TLR) signaling, which consequently results in dysfunctional T cell homing to the small intestine in individuals with chronic progressive infection. In this application I intend to: 1. Determine the frequency and functional capacity of HIV specific gut mucosal CD8+ T cells in patients with progressive and controlled infection using novel assays of cytokine secretion and T cell killing, 2. Define the contribution of the gut microenvironment to T cell impairment by assessing the effects of E-cadherin binding to the inhibitory receptor KLRG1 on HIV specific CD8+ T cells, and 3. Investigate the role of HIV encoded TLR ligands in intestinal DC production of retinoic acid and the effect of retinoic acid on T cell gut homing receptor expression. RELEVANCE (See instructions): The majority of the body's immune cells reside in the gastrointestinal tract and this region is intensely active during HIV infection. The effects of HIV in the gut, however, remain incompletely studied. We are developing new, state-of-the-art techniques to better assess the immune system in the gut of patients with progressive HIV disease and in unique individuals who are able to control infection without medicines. These studies will provide insights that will assist in the development of more effective therapies and vaccines against HIV.