Glutaminase and its neurotoxic link to HAND

 描述（由申请人提供）：尽管抗逆转录病毒治疗有效，但影响HIV感染者的HIV相关神经认知障碍（HAND）继续增加。HAND的流行和抗逆转录病毒治疗后神经认知功能障碍的不完全逆转需要新的治疗方法。在HAND的各种病理生理学中，突触功能障碍可能是认知障碍的基础。有趣的是，达特，一种必需的HIV-1病毒蛋白，存在于接受cART病毒学控制的个体的脑脊液中。此外，小鼠脑特异性HIV蛋白达特表达模拟了后cART时代HAND病理学的关键方面，表明达特可能是接受cART的患者持续中枢神经系统并发症的原因。已知达特通过兴奋性毒性机制引起神经元损伤。此外，与未感染的对照组相比，HIV-1感染患者的血浆和脑脊液中的谷氨酸浓度显著较高。谷氨酸水平升高会破坏大脑中的正常神经传递，导致HIV-1感染的神经发病机制。在过去的十年中，我们已经确定，阻断谷氨酰胺酶（GLS）的活性，谷氨酸生产的主要酶，可以减轻巨噬细胞和小胶质细胞的神经炎症和神经毒性反应。我们已经证明了先天性免疫激活和促炎对巨噬细胞、小胶质细胞和神经元中GLS功能的因果作用。此外，我们已经观察到巨噬细胞、小胶质细胞和神经元通过可能导致神经元损伤的未鉴定的机制释放GLS。细胞外囊泡（EV），包括微泡和外泌体，已成为GLS释放的重要细胞机制。因此，在目前的建议中，我们假设释放的GLS含有EV是一个关键的致病事件，在HIV-1介导的神经元损伤和海马突触功能障碍。此外，我们假设通过GLS抑制剂阻断异常上调/释放的GLS可能对HAND有治疗作用。将提供以下信息：GLS的脑特异性过表达是否足以诱导小鼠的脑炎症、损害突触完整性和认知，以及GLS基因的巨噬细胞特异性条件性敲除和含GLS微泡释放的阻断是否可以保护HAND的达特转基因小鼠模型中的神经元功能。此外，将在HAND相关动物模型中评价新型水溶性GLS抑制剂的治疗潜力。阐明GLS失调及其对HAND病理生理学的贡献将有助于开发用于治疗HAND和其他神经退行性疾病的潜在新药物。

 DESCRIPTION (provided by applicant): Despite the effectiveness of antiretroviral therapy, HIV-associated neurocognitive disorders (HAND) that affect HIV infected individuals continue to increase. The prevalence of HAND and the incomplete reversal of neurocognitive dysfunctions after antiretroviral therapy have called for novel therapeutic approaches. Among the various pathophysiology of HAND, synaptic dysfunction likely underlies cognitive impairments. Interestingly, Tat, an essential HIV-1 viral protein, is present in the cerebrospinal fluid of individuals virologically controlled on cART. Furthermore, Brain-specific HIV protein Tat expression in mice mimics key aspects of HAND pathology in the post-cART era, suggesting that Tat may be responsible for the sustained central nervous system complications in patients receiving cART. Tat is known to cause neuronal injury via excitotoxic mechanisms. Furthermore, HIV-1-infected patients have significantly higher concentrations of glutamate in their plasma and cerebrospinal fluid compared to uninfected controls. Elevated levels of glutamate disrupt normal neural transmission in the brain, contributing to the neuropathogenesis of HIV-1 infection. In the past decade we have established that blocking the activity of glutaminase (GLS), a primary enzyme for the production of glutamate, could alleviate macrophages and microglia neuroinflammatory and neurotoxic response. We have demonstrated causal effects of innate immune activation and proinflammatory on the GLS function in macrophages, microglia, and neurons. Furthermore, we have observed an intriguing release of GLS by macrophages, microglia, and neurons, through unidentified mechanism(s) that could cause neuronal injury. Extracellular vesicles (EVs), which include microvesicles and exosomes, have emerged as an important cellular mechanism for GLS release. Therefore, in the current proposal, we hypothesize that the release of GLS-containing EVs is a critical pathogenic event in HIV-1-mediated neuronal injury and hippocampal synaptic dysfunction. Moreover, we hypothesize that blocking aberrantly upregulated/released GLS through GLS inhibitors could have therapeutic effects in HAND. Information will be provided as whether brain-specific overexpression of GLS is sufficient to induce brain inflammation, impair synaptic integrity and cognition in mice, and whether macrophage-specific conditional knockout of GLS gene and blocking of GLS-containing microvesicles release could protect neuronal function in a Tat transgenic mouse model of HAND. Furthermore, novel water-soluble GLS inhibitors will be evaluated for their therapeutic potentials in HAND relevant animal models. The elucidation of the GLS dysregulation and its contribution to pathophysiology of HAND will aid in developing potential novel agents for the treatment of HAND and other neurodegenerative disorders.