Enhancing HIV-specific CTL by CD27/CD70 costimulation

描述（由申请人提供）：尽管HIV感染者产生大量抗原特异性CD 8 T细胞，但他们无法控制病毒，最终发展为临床AIDS。我们和其他人已经表明，新鲜分离的HIV特异性CD 8 T细胞功能受损。进一步的初步结果表明，HIV特异性T细胞，而不是CMV特异性T细胞从同一感染个体表现出不成熟的表型特征。HIV特异性CD 8 T细胞与对其他良好控制的慢性病毒如CMV应答的CD 8 T细胞之间的一个显著表型差异是不能下调TNF家族共刺激分子CD 27。CD 27下调通常发生在与其配体CD 70相互作用后，这种相互作用似乎对T细胞的终末成熟和关键细胞毒性分子穿孔素的表达至关重要。因此，HIV感染的潜在缺陷可能是不能表达CD 70，导致不能产生CD 27触发的共刺激信号。为了检验这一假设，在目的1中，我们将研究外源性提供CD 70是否恢复或增强HIV特异性CD 8 T细胞的增殖、细胞毒性和IFN-γ分泌。由于EBV转化的B类淋巴母细胞系（BLCL）大量表达CD 70，我们将首先测试阻断/消除自体BLCL上的分子是否会降低其刺激HIV特异性CTL的能力。我们还将在有和没有抗原刺激的细胞离体培养期间以可溶形式外源性地或通过慢病毒递送提供CD 70，并测试它们杀死HIV感染和肽脉冲靶标的能力以及产生细胞因子的能力。 由于HIV感染者的一小部分，长期不进展者能够在没有治疗的情况下控制病毒，因此在第二个具体目标中，我们将检查完整的CD 70共刺激通路是否负责维持这些受试者中功能性病毒特异性CD 8 T细胞。我们将使用阻断抗体、CD 27 Ig嵌合体和RNAi在离体刺激过程中阻断CD 27/CD 70相互作用，并测试这种治疗是否降低了它们的反应性。

DESCRIPTION (provided by applicant): Although HIV infected individuals generate a large number of antigen-specific CD8 T cells, they are unable to control the virus and eventually develop clinical AIDS. We, and others have shown that freshly isolated HIV-specific CD8 T cells are functionally impaired. Further preliminary results suggest that HIV-specific T cells but not CMV-specific T cells from the same infected individual exhibit phenotypic features of immaturity. One striking phenotypic difference between HIV-specific CD8 T cells from CD8 T cells responding to other well-controlled chronic viruses such as CMV, is the failure to downmodulate the TNF family costimulatory molecule CD27. CD27 downmodulation normally occurs after interaction with its ligand CD70, and this interaction appears to be critical for the terminal maturation of T cells and expression of the key cytotoxic molecule perforin. Thus, the underlying defect in HIV infection may be a failure to express CD70, resulting in the failure to generate CD27 triggered costimulatory signals. To test this hypothesis, in Aim 1, we will investigate whether providing CD70 exogenously restores or enhances proliferation, cytotoxicity and IFN-gamma secretion of HIV-specific CD8 T cells. As EBV-transformed B lymphoblastoid cell lines (BLCLs) express CD70 abundantly, we will first test if blockade/abrogation of the molecule on autologous BLCLs diminishes their ability to stimulate HIV-specific CTL. We will also provide CD70 exogenously in soluble form or by lentiviral delivery during ex vivo culture of the cells with and without antigen stimulation, and test their ability to kill HIV-infected and peptide-pulsed targets and to produce cytokines. Because a small subpopulation of HIV-infected individuals, the long-term nonprogressors are able to control the virus in the absence of treatment, in the second specific aim, we will examine whether an intact CD70 costimulation pathway is responsible for maintenance of a functional virus-specific CD8 T cells in these subjects. We will block CD27/CD70 interactions during ex vivo stimulation using blocking antibody, CD27Ig chimera and RNAi and test if this treatment diminishes their responsiveness.