Eradicating Latent SIV from the CNS by CCR5 Inhibition

描述(申请人提供)：联合抗逆转录病毒疗法(CART)极大地改变了艾滋病毒的流行，延缓了疾病和延长了生命。随着越来越重视从包括中枢神经系统在内的潜伏宿主中根除艾滋病毒的战略的制定，在已建立的艾滋病毒潜伏动物模型中评估治疗方法至关重要。为此，我们开发并表征了CART的SIV模型，该模型将外周血和脑脊液中的病毒载量降低到无法检测的水平。该模型的价值在于：1) CD4+T细胞和单核/巨噬细胞被感染，2)包括脑组织在内的组织中含有潜伏的病毒DNA，3)血液和淋巴组织中潜伏感染的静止CD4+细胞的数量与CART上HIV感染患者的数量相当。虽然CART显著降低了大脑中的SIV RNA，但与未经处理的感染SIV的猕猴相比，大脑中的SIV DNA水平没有变化，炎症标志物仍然升高。总之，我们的研究表明，抑制脑脊液和血浆病毒载量的CART并不针对中枢神经系统潜在的DNA储存库。CCR5抑制剂是具有潜在的中枢神经系统作用的抗HIV药物的候选药物。与其他类型的抗逆转录病毒药物相比，CCR5抑制剂马拉韦罗(MVC)具有高的中枢神经系统通透性(CPE=1.0)和最小的神经毒性。由于R5嗜性艾滋病毒在中枢神经系统中占主导地位，尽管存在CART，但艾滋病毒的间歇性复制可能会在大脑中持续存在，MVC治疗可以阻止中枢神经系统中额外细胞的感染。MVC还可能抑制脑内驻留效应细胞(包括小胶质细胞和星形胶质细胞)的免疫激活，并减少白细胞向中枢神经系统的募集。本课题组的刺激性SIV研究评估了CCR5抑制对SIV诱导的中枢神经系统损伤的影响。在感染SIV的恒河猴中，马拉韦罗单一疗法显著降低了CNS SIV DNA水平，并降低了关键的CNS炎症反应，这与接受CART治疗的动物形成鲜明对比。由于这些发现，这项建议侧重于通过添加马拉韦罗来加强对感染SIV的辫尾猕猴的CART治疗，以达到根除病毒的目标。我们的假设是，在感染SIV的猕猴的CART中加入中枢神经系统渗透剂CCR5抑制剂马拉韦罗，在A)减少大脑中的病毒DNA储备库和B)延迟CART退出时病毒的重新激活方面，将比单独使用CART有效得多。这些效应归因于MVC能够阻止CNS中新细胞靶点的感染，并通过CCR5抑制促炎信号。目的一是确定在CART中加入MVC是否降低了病毒DNA，并损害了SIV感染猕猴中枢巨噬细胞/小胶质细胞和星形胶质细胞以及周围组织和血液中静止的CD4+细胞和单核/巨噬细胞中潜伏病毒的重新激活。目的2比较CART+MVC方案和CART单独方案在停止治疗后预防或延迟SIV感染猕猴中枢神经系统储存库病毒重新激活的能力。目的3是确定在停止CART后继续进行MVC治疗是否能抑制来自中枢神经系统储存库或外周储存库的病毒的重新激活。

DESCRIPTION (provided by applicant): Combined antiretroviral therapy (cART) has dramatically changed the HIV epidemic, delaying disease and prolonging life. With increasing emphasis on development of strategies to eradicate HIV from latent reservoirs including the CNS, it is critical to evaluate therapeutic approaches in established animal models of HIV latency. To do so, we developed and characterized a SIV model of cART that reduced viral load in peripheral blood and cerebrospinal fluid to undetectable levels. The value of this model is : 1) CD4+ T cells and monocyte/ macrophages are infected, 2) tissues including the brain harbor latent viral DNA, and 3) the number of latently infected resting CD4+ cells in the blood and lymphoid tissues is comparable to that in HIV-infected patients on cART. While SIV RNA in brain was dramatically reduced by cART, SIV DNA levels in brain were unchanged compared to untreated SIV-infected macaques and inflammatory markers remained elevated. In sum, our studies illustrate that cART that suppresses CSF and plasma viral load does not target the CNS latent DNA reservoir. CCR5 inhibitors are promising anti-HIV drug candidates with potential beneficial CNS effects. The CCR5 inhibitor maraviroc (MVC) has high CNS penetrance (CPE = 1.0) and minimal neurotoxicity in comparison with other classes of antiretrovirals. As R5-tropic HIV predominates in the CNS and intermittent HIV replication may persist in the brain despite cART, MVC treatment could block infection of additional cells in the CNS. MVC also may dampen immune activation of resident effector cells in the brain, including microglia and astrocytes, and decrease recruitment of leukocytes to the CNS. Provocative SIV studies by our group evaluated the impact of CCR5 inhibition on SIV-induced CNS damage. In SIV-infected rhesus macaques, maraviroc monotherapy significantly reduced CNS SIV DNA levels and lowered key CNS inflammatory responses in sharp contrast with animals treated with cART. Because of these findings, this proposal focuses on intensification of cART therapy in SIV-infected pigtailed macaques by adding maraviroc with the goal of virus eradication. Our hypothesis is that adding the CNS penetrant CCR5 inhibitor maraviroc to cART in SIV- infected macaques will be much more effective than cART alone in A) reducing viral DNA reservoirs in brain and B) delaying virus reactivation upon withdrawal of cART. These effects are attributable to MVC's ability to both block infection of new cellular targets in the CNS and inhibit pro-inflammatory signaling through CCR5. Aim 1 is to determine whether adding MVC to cART reduces viral DNA and impairs reactivation of latent virus in macrophages/ microglia and astrocytes in the CNS and resting CD4+ cells and monocyte/macrophages in peripheral tissues and blood of SIV-infected macaques. Aim 2 will compare the ability of cART+MVC versus cART alone regimens to prevent or delay reactivation of virus from the CNS reservoir in SIV-infected macaques after cessation of therapy. Aim 3 is to determine whether continuing MVC therapy after stopping cART suppresses reactivation of virus from the CNS reservoir or peripheral reservoirs.