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

项目总结 HIV(PWH)患者神经系统并发症的患病率和发生率保持稳定 对于那些正在接受抗逆转录病毒治疗(ART)的老年人。消除慢性阻塞性肺疾病之间的紧密联系 外周和中枢神经系统的炎症和艾滋病毒蓄积物仍然是主要的治疗挑战。高架 骨桥蛋白/分泌型磷蛋白-1(OPN/SPP1)在中重度神经内科PWH中的表达 并发症在2008年首次报道。从那时起，OPN/SPP1高表达的RNA在 而人脑中更广泛地出现了神经退行性小胶质细胞。然而，还有很多事情要做 揭示OPN/SPP1‘S在HIV感染中脑内作用的基本分子机制(S)。 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已经 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/SPP1功能 是中枢神经系统在感染后大脑恢复和恢复内稳态所必需的。这是第一次，能够 为了在体内敲除OPN的表达，我们得到了更清晰的观点，即其功能特异性是上下文- 依附的。到目前为止，OPN/SPP1信号通路支持体内组织间隔内的病毒复制 因性别不同而有不同特征的机制。此外，OPN/SPP1的表达与 免疫细胞在周围器官中的滞留。OPN/SPP1支持更多的SIV贩运 单核细胞进入大脑，但人类细胞是否也是如此尚不清楚。我们发现使用微型- PET神经成像，当体内平衡被艾滋病毒感染破坏时，OPN/SPP1是一个有效的传感器和 大脑中神经炎症的调节剂。获得的另一个新见解是不仅检测到 发炎的小胶质细胞，但属于一种独特的“激活的”转位蛋白(TSPO)和酪氨酸羟基化酶 (Th)纹状体内的反应神经元。我们假设OPN作为传感器/调节器的保守性 成年哺乳动物中枢神经系统动态平衡的研究表明，它在 调节神经炎症的神经保护途径。此外，其分子机制是 组织上下文依赖和利用由小胶质细胞启动并由 纹状体中的特定神经元。梳理出机械的细节需要一种组合的方法 利用基本的生化和分子工具，体外原代细胞培养和最新的体内嵌合小鼠 模特们。重要的是，我们已经成功地证明了人-鼠嵌合体在 NSG-hCD34系统概括了神经炎症的关键方面，类似于神经艾滋病毒患者的情况。 对本提案综合目标的基本假设进行测试将确定哪些剪接变体 OPN/SPP1在中枢神经系统中活跃，确定为什么OPN/SPP1中断的新的机械性见解 增加小胶质细胞和特定神经元亚型的神经炎性信号，这些反应是如何 以及认知或情感行为是否发生改变。

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.