Enhancing HIV-specific CTL by CD27/CD70 costimulation

描述(申请人提供)：尽管HIV感染者产生大量抗原特异性CD8 T细胞，但他们无法控制病毒并最终发展为临床艾滋病。我们和其他人已经证明，新分离的HIV特异性CD8 T细胞功能受损。进一步的初步结果表明，来自同一感染者的HIV特异性T细胞而不是CMV特异性T细胞表现出不成熟的表型特征。HIV特异性CD8 T细胞与CD8 T细胞对其他控制良好的慢性病毒(如CMV)的一个显著表型差异是未能下调TNF家族共刺激分子CD27。CD27的下调通常发生在与其配体CD70相互作用后，这种相互作用似乎对T细胞的最终成熟和关键的细胞毒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表达CD70，导致不能产生CD27触发的共刺激信号。为了验证这一假设，在目标1中，我们将研究外源性提供CD70是否恢复或增强HIV特异性CD8 T细胞的增殖、细胞毒作用和干扰素-γ的分泌。由于EBV转化的B淋巴母细胞系(BLCL)大量表达CD70，我们将首先测试自体BLCL上CD70分子的阻断/取消是否会削弱它们刺激HIV特异性CTL的能力。我们还将在有和没有抗原刺激的细胞体外培养过程中，以可溶性形式或通过慢病毒传递的方式外源提供CD70，并测试它们杀死艾滋病毒感染和多肽脉冲靶标的能力以及产生细胞因子的能力。 由于只有一小部分HIV感染者，长期不进展者能够在没有治疗的情况下控制病毒，在第二个特定目标中，我们将检查完整的CD70共刺激通路是否负责维持这些受试者中具有功能的病毒特异性CD8T细胞。我们将在体外刺激过程中使用封闭抗体、CD27Ig嵌合体和RNAi来阻断CD27/CD70的相互作用，并测试这种治疗是否会降低它们的反应性。

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.