CD8 T Cell Replicative Senescence & HIV Disease

这项拟议的研究涉及在HIV疾病进展过程中积累的终末期记忆CD8T细胞群。具有类似特征的CD8T细胞是在细胞培养的最后阶段产生的，受到反复的抗原驱动的增殖。达到“复制衰老”这一终末状态的细胞的特征是不可逆的细胞周期停滞、对凋亡的抵抗、端粒缩短、细胞因子谱改变、抗病毒功能减弱以及CD28基因表达的永久性丧失。临床研究表明，高比例的CD8 T细胞缺乏CD28 CD8+CD28-的表达与老年人对流感疫苗的抗体反应降低和死亡风险增加以及各种抑制细胞功能有关，这表明感染艾滋病毒的人中CD8+CD28-的高比例可能影响疾病的进展。在细胞培养模型系统中探索这些相互作用的能力提供了一个无与伦比的机会，可以从实验上剖析HIV发病机制的几个基本方面的遗传和分子基础，并评估潜在的免疫调节策略。将实现以下具体目标： (1)探讨衰老对CD8T细胞功能的影响及其与HIV-1感染的关系。长期培养和克隆将被用于跟踪整个衰老过程中的功能、细胞因子的产生和相关的表型特征。从HIV感染者体内分离的表型相似的CD8 T细胞将在体外进行相应的功能和细胞因子变化的测试； (2)探讨CD8 T细胞衰老对其他免疫功能的间接影响。我们将比较衰老和早期传代的CD8T细胞培养上清对自体CD4T细胞功能、CD8效应器活性、B细胞抗体产生和树突状细胞提呈抗原的影响。已经在体外“老化”的CD8 T细胞的相互作用将用从HIV感染者身上分离的具有相同表型的细胞来验证； (3)。为了确定防止CD8T细胞复制衰老的策略是否也能防止AIMS 1和2中确定的一些有害免疫效应。将使用基因转导(hTERT，CD28)以及复制衰老过程中的雌激素效应来确定从直接和间接免疫效应方面维持HIV特异性CD8T细胞功能的最佳方法。这种新的方法来分析 HIV疾病中的免疫衰竭可能为延缓或防止进展为艾滋病的免疫治疗提供有前景的策略。

The proposed research concerns a population of end-stage memory CD8 T cells that accumulates during HIV disease progression. CD8 T cells with similar characteristics are generated as the final stage of cell cultures subjected to repeated rounds of antigen-driven proliferation. Cultures that have reached this terminal state of "replicative senescence" are characterized by irreversible cell cycle arrest, apoptosis resistance, shortened telomeres, altered cytokine profiles, reduced anti-viral functions, and permanent loss of CD28 gene expression. Clinical studies have shown that high proportions of CD8 T cells that lack CD28 expression are correlated with reduced antibody response to influenza vaccination and with increased mortality risk in the elderly, as well as with a variety of suppressor cell functions, suggesting that the high proportions of CD8+CD28 - in persons infected with HIV may affect disease progression. The ability to explore these interactions in cell culture model systems provides an unparalleled opportunity to experimentally dissect the genetic and molecular basis of several fundamental aspects of HIV pathogenesis and to evaluate potential immunomodulatory strategies. The following Specific Aims will be addressed: (1) To evaluate the effects of senescence on CD8 T cell function and correlate these findings to HIV-1 infection. Long-term cultures and clones will be used to follow function, cytokine production, and associated phenotypic characteristics during the entire trajectory to senescence. CD8 T cells with similar phenotypes isolated from HIV-infected persons will be tested ex vivo for the corresponding functions and cytokine changes; (2) To explore the indirect effects of CD8 T cell senescence on other immune functions. Cells and cell-free supernatants from senescent versus early passage CD8 T cell cultures will be compared for effects on autologous CD4 T cell function, CD8 effector activity, B cell antibody production and antigen-presentation by dendritic cells. Interactions identified for CD8 T cells that have been "aged" in vitro will be validated using cells with the same phenotype isolated from HIV-infected persons; (3). To determine if strategies that prevent replicative senescence in CD8 T cells also prevent some of the deleterious immune effects identified in Aims 1 and 2. Gene transduction (hTERT, CD28) as well as estrogen effects on the process of replicative senescence will be used to determine the optimal means for maintaining the functional profile of HIV-specific CD8 T cells with respect to both direct and indirect immune effects. This novel approach to analysis of the immune exhaustion in HIV disease may yield promising strategies for immunotherapy to retard or prevent progression to AIDS.