CD8 T Cell Replicative Senescence & HIV Disease

这项研究涉及在HIV疾病进展过程中积累的终末期记忆CD 8 T细胞群。具有相似特征的CD 8 T细胞作为细胞培养物的最后阶段产生，所述细胞培养物经历重复轮的抗原驱动的增殖。已经达到这种“复制性衰老”的终末状态的培养物的特征在于不可逆的细胞周期停滞、细胞凋亡抗性、缩短的端粒、改变的细胞因子谱、降低的抗病毒功能和永久性丧失CD 28基因表达。临床研究表明，高比例的缺乏CD 28的CD 8 T细胞， 表达与对流感疫苗接种的抗体应答降低和老年人死亡风险增加以及多种抑制细胞功能相关，表明HIV感染者中高比例的CD 8 + CD 28-可能影响疾病进展。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，以实验解剖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。将致力于实现以下具体目标： (1)评估衰老对CD 8 T细胞功能的影响，并将这些发现与HIV-1感染相关联。长期培养物和克隆将用于跟踪整个衰老轨迹期间的功能、细胞因子产生和相关表型特征。从HIV感染者中分离的具有相似表型的CD 8 T细胞将被离体检测相应的功能和细胞因子变化; (2)探讨CD 8 T细胞衰老对其他免疫功能的间接影响。将比较衰老与早期传代CD 8 T细胞培养物的细胞和无细胞上清液对自体CD 4 T细胞功能、CD 8效应子活性、B细胞抗体产生和树突状细胞抗原呈递的影响。将使用从艾滋病毒感染者分离的具有相同表型的细胞验证在体外“老化”的CD 8 T细胞中鉴定的相互作用; （三）、确定预防CD 8 T细胞复制性衰老的策略是否也预防了目的1和2中鉴定的一些有害免疫作用。基因转导（hTERT，CD 28）以及雌激素对复制衰老过程的影响将用于确定维持HIV特异性CD 8 T细胞在直接和间接免疫作用方面的功能特征的最佳方法。这种新的分析方法， HIV疾病中免疫衰竭可能产生有希望的免疫治疗策略，以延缓或预防进展为AIDS。

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.