HIV-OPN/SPP1Triad II: Molecular Pathways Regulating Neuronal-Glial Inflammation in the Brain

项目摘要 艾滋病毒感染者（PWH）神经系统并发症的患病率和发病率保持稳定 抗逆转录病毒治疗（ART）的老年人。消除慢性病与慢性病之间的紧密联系 外周和CNS中的炎症和HIV储库仍然是主要的治疗挑战。升高 骨桥蛋白/分泌型磷蛋白-1（OPN/SPP 1）在伴有中重度神经功能障碍的PWH中的作用 2008年首次报道了并发症。从那时起，高OPN/SPP 1 RNA表达的重要性， 人类大脑和更广泛的神经退行性小胶质细胞已经出现。然而，仍有许多工作要做， 揭示OPN/SPP 1在HIV感染中大脑中作用的基本分子机制。 在这方面，我们在过去几年中使用体外和体内实验模型进行的研究表明， 开始缩小差距。从我们的集体发现中出现了一个基本概念：OPN/SPP 1功能 在CNS中是脑恢复和感染后恢复体内平衡所必需的。第一次，能够 为了在体内敲低OPN的表达，我们获得了一个更清晰的观点，即它的功能特异性是环境- 依赖。OPN/SPP 1信号转导通过迄今为止的一种新的途径支持病毒在组织区室中的体内复制。 随性别而变化的未表征的机制。此外，OPN/SPP 1表达与 免疫细胞在外周器官中的滞留。OPN/SPP 1支持增加SIV的贩运 单核细胞的大脑，但是否同样适用于人类细胞尚不清楚。我们发现使用微- PET神经成像，当体内平衡被HIV感染破坏时，OPN/SPP 1是一个有效的传感器， 大脑中神经炎症的调节器。另外一个新的发现是， 发炎的小胶质细胞，但一个独特的子集的“激活”转运蛋白（TSPO）和酪氨酸羟化酶 (TH)纹状体的反应神经元我们假设骨桥蛋白作为一种传感器/调节器的保守性 成年哺乳动物中枢神经系统内稳态的变化表明，它在中枢神经系统内稳态中起着关键的机制作用。 调节神经炎症的神经保护通路。此外，分子机制是 组织环境依赖性，并利用小胶质细胞启动的配体-受体动力学， 纹状体中的特定神经元梳理出的机械细节需要一个组合的方法 使用基本的生物化学和分子工具，体外原代细胞培养和最新的体内嵌合小鼠， 模型重要的是，我们已经成功地证明了小鼠-人嵌合体中的代表， NSG-hCD 34系统重现了神经炎症的关键方面，类似于在神经HIV患者中看到的。 测试本提案的综合目标的基本假设将确定哪些剪接变体 的OPN/SPP 1在CNS中是活跃的，确定为什么OPN/SPP 1的破坏的新的机制见解， 增加小胶质细胞和特定神经元亚型的神经炎症信号，这些反应是如何 调节以及认知或情感行为是否改变。

PROJECT SUMMARY The prevalence and incidence of neurological complications in people with HIV (PWH) remains steady for those aging on antiretroviral therapy (ART). Eliminating the tight association between chronic inflammation and HIV reservoirs in the periphery and CNS remain major therapeutic challenges. Elevated osteopontin/secreted phosphoprotein-1 (OPN/SPP1) in PWH having moderate to severe neurological complications was first reported in 2008. Since this time, the importance of high OPN/SPP1 RNA expression in human brain and more widely in neurodegenerative microglia has emerged. However, much remains to uncover about OPN/SPP1's fundamental basic molecular mechanism (s) of action in the brain in HIV infection. In this regard, our investigations over the past several years using in vitro and in vivo experimental models have begun to close the gap. A fundamental concept has emerged from our collective findings: OPN/SPP1 function is required in the CNS for brain recovery and return to homeostasis after infection. For the first time, able to knockdown OPN expression in vivo, we obtained a clearer view that its functional specificity is context- dependent. OPN/SPP1 signaling supports viral replication in vivo within tissue compartments via an as yet uncharacterized mechanism that varies with sex. In addition, OPN/SPP1 expression is strongly correlated with the retention of immune cells in the peripheral organs. OPN/SPP1 supports increased trafficking of SIV monocytes to the brain, but whether the same is true for human cells is not known. We discovered using micro- PET neuroimaging, that when homeostasis is disrupted by HIV infection, OPN/SPP1 is a potent sensor and regulator of neuroinflammation in the brain. An additional novel insight gained was the detection not only of inflamed microglia, but of a unique subset of “activated” translocator protein (TSPO) and tyrosine hydroxylase (TH) reactive neurons in the striatum. We hypothesize that the conservation of OPN as a sensor/regulator of CNS homeostasis in adult mammals suggests that it plays a key central mechanistic role in neuroprotective pathways that modulate neuroinflammation. Moreover, the molecular mechanisms are tissue context-dependent and utilize ligand-receptor dynamics initiated by microglia and propagated by specific neurons in the striatum. Teasing out of the mechanistic details requires a combinatorial approach using basic biochemical and molecular tools, in vitro primary cell culture and the latest in vivo chimeric mouse models. Importantly, we have successfully demonstrated that the mouse-human chimera represented in the NSG-hCD34 system recapitulates key aspects of neuroinflammation similar to that seen in people with neuroHIV. Testing of the underlying hypotheses of the integrated aims of this proposal will determine which splice variants of OPN/SPP1 are active in the CNS, identify new mechanistic insights into why disruption of OPN/SPP1 increases neuroinflammatory signaling in microglia and specific neuronal subtypes, how these responses are regulated and whether cognition or affective behaviors are altered.