Role of Viral Reservoirs in the Pathogenesis of HIV Disease

在过去的几年里，我们一直在研究潜伏感染的静止的CD4+T细胞和持续的病毒复制在HIV感染的发病机制中的作用，以及这个蓄水池对HIV感染者治疗的影响。我们先前证明，静息的CD4+T细胞隔间中的潜伏病毒库在几乎所有接受有效抗病毒治疗的感染者中持续存在。因此，这个病毒库是在体内根除艾滋病毒的主要障碍。此外，我们意识到，艾滋病毒在接受有效抗病毒治疗的慢性感染者中持续低水平复制，使他们在很长一段时间内持续无病毒感染。在过去的一年里，我们的研究集中在：1)描述艾滋病毒在长期接受有效抗逆转录病毒治疗的感染者中持续存在的机制，以及2)检查加强抗逆转录病毒治疗对已接受临床成功药物治疗的感染者的病毒库衰败和大小的影响。 首先，我们调查了接受有效抗逆转录病毒治疗不同时间的人中残留艾滋病毒的存在和状况，并检查了艾滋病毒持续存在于这些人的静止CD4+T细胞中的潜在机制。有人提出，HIV存在于受感染的静止CD4+T细胞中是病毒学上的静止状态。我们证明，在接受有效抗逆转录病毒治疗的感染者的血液中，表达程序性死亡(PD)-1基因的静息CD4+T细胞亚群携带的HIV前病毒DNA水平显著高于PD-1阴性的静息CD4+T细胞。大多数PD-1+静息的CD4+T细胞表达组织归巢受体CXCR3，这表明这些细胞最近可能已经从不同的组织部位迁移到外周血室。临床上成功接受抗逆转录病毒治疗的大多数患者的PD-1+静息CD4+T细胞在没有任何激活刺激的情况下自发释放HIV。这表明这些细胞在生理上不同于未分离的潜伏感染的、静息的CD4+T细胞。综上所述，我们的数据表明，PD-1+静息的CD4+T细胞代表着一种独特的感染细胞群，在感染者的抗逆转录病毒治疗过程中持续存在，这可能需要一种新的治疗方法来实现体内病毒的完全清除。 其次，在过去的一年里，我们启动了一项临床试验，以检查抗逆转录病毒治疗强化如何影响临床成功用药超过3年的感染者的病毒库的衰败。尽管治疗策略取得了成功，但主要由于各种病毒库的持续存在，在接受有效抗逆转录病毒治疗的感染者中无法根除艾滋病毒。我们最近证明了HIV在激活的和静止的CD4+T细胞中的持久性，并为接受长达9.1年有效抗逆转录病毒治疗的无精症患者这些细胞间的交叉感染提供了证据。这表明潜伏感染的静止的CD4+T细胞正在不断重新激活，并在体内传播病毒。为了降低残留病毒复制水平并设计有效的抗逆转录病毒策略以根除病毒，我们正在研究联合使用新开发的抗逆转录病毒药物-整合酶抑制剂雷替格雷对正在接受有效抗逆转录病毒治疗一段时间的感染者外周血和肠道相关淋巴组织中的病毒库腐烂的影响。我们即将完成上述临床试验(96周)，并将在未来几个月对各种免疫学和病毒学参数进行分析。

For the past several years, we have been investigating the role of latently infected, resting CD4+ T cells and persistent viral replication in the pathogenesis of HIV infection and the impact of this reservoir on the treatment of HIV-infected individuals. We previously demonstrated that the latent viral reservoir in the resting CD4+ T cell compartment persists in virtually all infected individuals receiving effective antiviral therapy. Consequently, this viral reservoir is a major impediment to the eradication of HIV in vivo. In addition, we realized that HIV continually replicates at low levels in chronically infected individuals who are receiving effective antiviral therapy that renders them consistently aviremic for prolonged periods of time. Over the past year, we have focused our research on: 1) delineating the mechanisms by which HIV persists in infected individuals receiving effective antiretroviral therapy for extended periods of time and 2) examining the effect of intensifying antiretroviral therapy on the decay and size of viral reservoirs in infected individuals who had been on clinically successful drug regimens. First, we investigated the presence and status of residual HIV in individuals who had received effective antiretroviral therapy for varying periods of time and we examined the underlying mechanisms by which HIV persists in resting CD4+ T cells of such individuals. It has been proposed that the HIV present in infected resting CD4+ T cells is virologically quiescent. We demonstrated that a subset of resting CD4+ T cells that express the programmed death (PD)-1 gene carry substantially higher levels of HIV proviral DNA compared to PD-1-negative resting CD4+ T cells in the blood of infected individuals receiving effective antiretroviral therapy. The majority of PD-1+ resting CD4+ T cells express CXCR3, a tissue homing receptor, which suggests that these cells may have recently migrated out of various tissue sites into the peripheral blood compartment. PD-1+ resting CD4+ T cells from the majority of patients on clinically successful antiretroviral therapy spontaneously released HIV in the absence of any activating stimuli. This suggests that these cells are physiologically distinct from unfractionated latently infected, resting CD4+ T cells. Taken together, our data suggest that PD-1+ resting CD4+ T cells represent a unique population of infected cells that persists during antiretroviral therapy in infected individuals and that may require a novel therapeutic approach in order to achieve complete clearance of virus in vivo. Second, over the past year, we initiated a clinical trial to examine how antiretroviral therapy intensification affects the decay of viral reservoirs in infected individuals who had been on clinically successful drug regimens for greater than 3 years. Despite the success of therapeutic strategies, it has not been possible to eradicate HIV in infected individuals receiving effective antiretroviral therapy mainly due to the persistence of various viral reservoirs. We have recently demonstrated the persistence of HIV in activated as well as resting CD4+ T cells and provided evidence for cross-infection between these cellular compartments in aviremic patients receiving up to 9.1 years of effective antiretroviral therapy. This suggests ongoing reactivation of latently infected, resting CD4+ T cells and spread of virus in vivo. In order to decrease levels of residual viral replication and to design effective antiretroviral strategies aimed at eradicating virus, we are examining the effect of co-administering a newly developed antiretroviral drug, the integrase inhibitor raltegravir, on the decay of the viral reservoir in peripheral blood and gut-associated lymphoid tissues of infected individuals who are receiving effective antiretroviral therapy for some time. We are near the completion of the above clinical trial (96 weeks) and will conduct analyses of various immunologic and virologic parameters in the coming months.