Molecular mechanisms underlying HIV & Cocaine-mediated microglial activation: Targeting NLRP3 inflammasome

HIV的分子机制

• 批准号: 10450546
• 负责人: Shilpa J. Buch
• 金额: $ 1.52万
• 依托单位: UNIVERSITY OF NEBRASKA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-30 至 2021-11-18
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10450546
• 关键词: Affect; Astrocytes; Behavior assessment; Binding; Blood - brain barrier anatomy; Brain; CASP1 gene; Caspase; Cells; Cocaine; Cocaine Abuse; Complex; Data; Development; Disease; Down-Regulation; Drug abuse; Enzyme-Linked Immunosorbent Assay; Exposure to; Future; Gene Silencing; Genetic Transcription; HIV; HIV-associated neurocognitive disorder; Human; IL18 gene; Immune; In Vitro; Individual; Inflammasome; Inflammatory Response; Interleukin-1 beta; Leucine-Rich Repeat; Mediating; Memory; Messenger RNA; MicroRNAs; Microglia; Molecular; Motor Activity; Multiprotein Complexes; Mus; Neurocognitive; Neurocognitive Deficit; Neuroglia; Nuclear Translocation; Nucleotides; Pathway interactions; Pharmacology; Phosphorylation; Prevalence; Process; Proteins; Quality of life; Reactive Oxygen Species; Rodent; Rodent Model; Role; Signal Pathway; Signal Transduction; Site; Testing; Time; Trans-Activators; Transgenic Organisms; Up-Regulation; Western Blotting; antiretroviral therapy; base; combinatorial; comorbidity; cytokine; cytotoxic; efficacy testing; in vivo; inhibitor/antagonist; neuroinflammation; novel therapeutics; response; symptomatology

In the current era of combination antiretroviral therapy (cART), there is increased prevalence of HIV-associated neurocognitive disorders (HAND) with about 30-50% of HIV-infected individuals afflicted with varying degrees of neurocognitive impairments, substantially affecting their quality of life. It is well-recognized that despite cART, there is unabated persistence & presence of early HIV protein(s) such as the cytotoxic transactivator of transcription (TAT), that contributes to neuroinflammation. Adding fuel to the mix is the comorbidity of drug abuse in HIV-infected individuals, which further exacerbates microglial activation & thus symptomatology of HAND. Until recently, CNS was considered as an immune-privileged site, however, a recent paradigm shift in our understanding has revealed the role of cytosolic, multiprotein complexes, belonging to the nucleotide-binding domain leucine-rich repeat containing (NLR) protein superfamily, termed as “inflammasomes,” in various neuroinflammatory diseases. Assembly of these multiprotein complexes activates the proinflammatory caspases (specifically caspase 1), leading, in turn, to the cleavage & release of IL1β & 1L18, consequently resulting in a potent inflammatory response. Among the various NLRs, NLRC5 & NLRP3 are highly expressed in microglia & differentially regulate inflammatory responses. In our efforts to understand the combinatorial effects of HIV Tat & cocaine on Mg activation, we have made several exciting preliminary observations: 1) Exposure of rodent primary Mg to both HIV Tat & cocaine demonstrated significantly downregulated expression of NLRC5, with a concomitant upregulation of NLRP3 and, exacerbated Mg activation compared to cells exposed to either agent alone; 2) Rodent Mg exposed to HIV TAT demonstrated time-dependent upregulation of microRNA (miR)-34a, leading, in turn, to downregulation of its target - NLRC5; 3) Cocaine-mediated activation of Mg involved induction of reactive oxygen species (ROS), that was accompanied with defective mitophagy & subsequent oligomerization of NLRP3 inflammasome complex, leading to induced expression of mature (m)IL1β & IL18; 4) NLRP3 inhibitor - MCC950 mitigated cocaine-mediated activation of Mg. Based on these observations, we hypothesize that the co-operative effects of HIV TAT & cocaine on Mg activation involve two processes: a) downregulated expression of NLRC5 resulting in activation of NFκB (signal 1), leading, in turn, to transcriptional upregulation of NLRP3, pro IL1β & IL18, & b) induction of ROS-mediated defective mitophagy (signal 2), which, in turn, induces activation of NLRP3 inflammasome, resulting in increased cleavage & secretion of mIL1β & IL18. The hypothesis will be tested in two SA: 1) Explore the molecular mechanism(s) underlying HIV & cocaine- mediated induction of the NLRP3 inflammasome leading to Mg activation and 2) To validate in vivo the role of NLRC5/NFκB & ROS/defective mitophagy/NLRP3 axes underlying HIV Tat & cocaine-mediated activation of Mg. Understanding the mechanisms responsible for microglial activation induced by HIV & cocaine will set the stage for the future development of novel therapeutics aimed at dampening the neuroinflammatory responses.

在当今联合抗逆转录病毒疗法 (cART) 的时代，艾滋病毒相关疾病的患病率有所增加 神经认知障碍（HAND），约 30-50% 的 HIV 感染者患有不同程度的神经认知障碍 神经认知障碍，严重影响他们的生活质量。众所周知，尽管有 cART， 早期 HIV 蛋白的持续存在和存在有增无减，例如细胞毒性反式激活蛋白 转录（TAT），导致神经炎症。药物滥用的合并症更是雪上加霜 在 HIV 感染者中，这进一步加剧了小胶质细胞的激活，从而加剧了 HAND 的症状。 直到最近，中枢神经系统还被认为是免疫特权部位，然而，最近我们的范式发生了转变 理解已经揭示了胞质多蛋白复合物的作用，属于核苷酸结合 富含亮氨酸重复序列（NLR）的蛋白超家族，被称为“炎性体”，在各种 神经炎症疾病。这些多蛋白复合物的组装激活促炎半胱天冬酶 （特别是 caspase 1），进而导致 IL1β 和 1L18 的裂解和释放，从而导致 强烈的炎症反应。在各种 NLR 中，NLRC5 和 NLRP3 在小胶质细胞中高表达，并差异调节炎症反应。在我们努力了解 HIV Tat 和可卡因对镁激活的组合影响的过程中，我们做出了一些令人兴奋的初步观察：1) 啮齿动物的暴露 HIV Tat 和可卡因的初级镁显示 NLRC5 的表达显着下调， 与暴露于任一药物的细胞相比，NLRP3 伴随上调，并且 Mg 活化加剧 独自的; 2) 暴露于 HIV TAT 的啮齿动物 Mg 表现出 microRNA (miR)-34a 的时间依赖性上调， 进而导致其目标 NLRC5 的下调； 3) 可卡因介导的镁激活涉及诱导 活性氧（ROS），伴随有缺陷的线粒体自噬和随后的 NLRP3 炎性体复合物寡聚化，导致成熟 (m)IL1β 和 IL18 的诱导表达； 4） NLRP3 抑制剂 - MCC950 减轻可卡因介导的 Mg 激活。根据这些观察，我们 假设 HIV TAT 和可卡因对 Mg 激活的协同作用涉及两个过程：a) NLRC5 表达下调导致 NFκB（信号 1）激活，进而导致转录 NLRP3、pro IL1β 和 IL18 的上调，b) 诱导 ROS 介导的缺陷性线粒体自噬（信号 2），其中， 反过来，诱导 NLRP3 炎性体的激活，导致 mIL1β 和 IL18 的裂解和分泌增加。 该假设将在两个 SA 中得到检验：1）探索 HIV 和可卡因的分子机制 - 介导的 NLRP3 炎症小体诱导导致 Mg 激活，2) 验证体内作用 NLRC5/NFκB 和 ROS/有缺陷的线粒体自噬/NLRP3 轴是 HIV Tat 和可卡因介导的 Mg 激活的基础。 了解 HIV 和可卡因诱导小胶质细胞激活的机制将为我们奠定基础 促进旨在抑制神经炎症反应的新疗法的未来发展。