CD8+ T cell effector transcriptional programming in SIV infection

描述(申请人提供)：最近我们证明了T-bet在人CD8+T细胞中的表达与CD8+T细胞效应功能直接相关。在慢性HIV感染中，HIV特异性CD8+T细胞中T-bet的低表达与效应性CD8+T细胞反应差和控制HIV病毒血症失败有关。此外，我们的初步数据显示，尽管在急性HIV感染期间有大量(40-75%的T细胞)急性效应CD8+T细胞反应，但这些反应无法维持，最终导致无法持久地控制HIV病毒血症，这可能是由于T-bet调节失调所致。在急性HIV感染期间，HIV特异性的CD4+T细胞也会上调T-bet(这是Th1功能所必需的)，但在感染后的几周内就会失去这种表达。这种缺失可能会对HIV特异性CD8+T细胞效应器功能的正确编程、成熟和维持产生严重影响，而CD8+T细胞效应器功能对于长期控制HIV病毒载量至关重要。在这里，我们将在恒河猴模型中解决这些概念，以便解决两个假设：1)我们假设SIV/HIV-1特异性CD8+T细胞高表达T-bet能够在功能上对病毒复制和后续疾病进展产生保护性反应，并且未能表达足够的T-bet会导致效应器功能丧失和功能衰竭，2)T-bet介导的CD4+T细胞Th1反应的快速丧失将从根本上改变后续T细胞帮助，这是正确的HIV-1特异性CD8+T细胞发育和维持效应器和记忆功能所必需的。在目标1中，我们将确定在急性SIV感染过程中SIV特异的CD4+和CD8+T细胞中T-bet表达的动力学，以及这些功能特性与诱导免疫逃逸倾向之间的关系。在急性SIV感染期间，将对动物进行连续尸检，以便在多个组织间隔内评估这些因素。在目标2中，我们将探索CD4+T细胞在促进最佳T-bet表达CD8+T细胞中的作用。我们将通过两种方法来解决这一问题：第一，我们将通过早期抗逆转录病毒治疗来保护CD4+T细胞的功能；第二，我们将在SIV挑战之前耗尽CD4+T细胞。在这两种方法中，我们将监测对CD8+T细胞隔间的结果影响，特别关注T-bet的表达。我们还将描述在这些情况下诱导免疫逃逸的倾向，并使用微阵列分析更广泛地评估CD8+T细胞功能。最后，在目标3中，我们将进行一项SIV挑战研究，以确定在HIV精英控制的Mamu B*08/B*17模型中，SIV特异性CD4+T和CD8+T细胞中T-bet的表达在预测精英控制或疾病进展中的作用。总之，这些互补的目的将确定T-bet在HIV/SIV感染中保护性CD4+和CD8+T细胞反应中的重要性，并为HIV疫苗开发提供保护性T细胞功能编程的关键信息。

DESCRIPTION (provided by applicant): Recently we demonstrated that T-bet expression in human CD8+ T cells is directly correlated to CD8+ T cell effector function. In chronic HIV infection, low expression of T-bet within HIV-specific CD8+ T cells is associated with poor effector CD8+ T cell responses and a failure to control HIV viremia. Furthermore, our preliminary data demonstrates that despite a massive (40-75% of T cells) acute effector CD8+ T cell response during acute HIV infection, these responses cannot be maintained and ultimately result in failure to durably control HIV viremia perhaps due dysregulation of T-bet. HIV specific CD4+ T cells during acute HIV infection also upregulate T-bet (as is required for Th1 function), but lose this expression within weeks of infection. This loss likely has severe ramifications on the proper programming, maturation, and maintenance of HIV-specific CD8+ T cell effector function that is critical for long-term control of HIV viral load. Here, we will address these concepts in the rhesus macaque model in order to address two hypotheses: 1) we hypothesize that high T- bet expression by SIV/HIV-1 specific CD8+ T cells enables functionally protective responses against viral replication and subsequent disease progression, and that the failure to express adequate T-bet leads to loss of effector function and functional exhaustion, and 2) that rapid loss of T-bet mediated CD4+ T cell Th1 responses will fundamentally alter subsequent T cell help necessary for proper HIV-1-specific CD8+ T cell development and maintenance of effector and memory function. In Aim 1, we will determine the kinetics of T-bet expression within SIV-specific CD4+ and CD8+ T cells during acute SIV infection, and the relationship between these functional properties and the propensity to induce immune escape. Animals will be serially necropsied during acute SIV infection in order to assess these factors within multiple tissue compartments. In Aim 2, we will then explore the role of CD4+ T cell help in promoting optimal T-bet expressing CD8+ T cells. We will approach this in two ways~ first we will preserve CD4+ T cell function through early antiretroviral therapy, and second we will deplete CD4+ T cells prior to SIV challenge. In both approaches we will monitor the resultant effects upon the CD8+ T cell compartment with a particular focus on T-bet expression. We will also characterize the propensity to induce immune escape in these situations, and more broadly assess CD8+ T cell function using microarray analysis. Finally, in Aim 3, we will conduct an SIV challenge study to define the role of T-bet expression in SIV-specific CD4+ T and CD8+ T cells in predicting elite control or disease progression in the Mamu B*08/B*17 model of HIV elite control. Together, these complementary Aims will define the importance of T-bet in protective CD4+ and CD8+ T cell responses in HIV/SIV infection, and provide key information on protective T cell functional programming for HIV vaccine development.