Chloride channel-dependent mechanisms of opiate and HIV-induced synaptodendritic injury

HIV-1（PWH）感染者的阿片类药物使用障碍（OUD）加剧了神经HIV的病理生物学， 通过涉及直接外周（例如， 免疫抑制）和CNS（例如，神经炎症、血脑屏障损伤和神经元损伤） 方面的影响.虽然多巴胺能兴奋毒性仍然是HIV依赖性神经元损伤的主要驱动力， 我们实验室的新证据表明，抑制性GABA能控制和[Cl−]i稳态的丧失 不仅导致抑制作用的丧失，而且还增加谷氨酸的兴奋性/神经毒性作用， NMDA和AMPA受体。这个提议直接检验了[Cl−] i依赖的净损失的假设， 神经元抑制将增加兴奋并促进兴奋毒性。在成熟神经元中，细胞内Cl− 浓度（[Cl−]i）由膜离子通道（GABAA和甘氨酸受体）动态调节， Cl−通道和转运蛋白。通过控制[Cl−]i，这些通道和转运蛋白调节Cl− 平衡电位（EC 1）和神经元抑制，我们已经表明，KCC 2功能丧失， OUD/neuroHIV模型导致[Cl−]i增加，ECl升高和兴奋性毒性。我们发现了一个以前 鉴定了一种ClC-1样电压依赖性Cl−通道，其差异调节多巴胺的兴奋性， 受体D1和D2表达（分别为D1和D2）纹状体中型棘神经元（MSN）， 被阿片类药物和艾滋病病毒达特破坏。我们假设阿片类药物和HIV-1通过一种新的途径破坏[Cl-]i的稳态。 电压门控ClC Cl−通道导致突触树突损伤。这一假设将在 如果得到证实，这将是我们对阿片类药物和艾滋病毒如何相互作用的理解的概念转变。 导致兴奋性毒性。目标1将确定阿片类药物和艾滋病毒失调电压的机制， 依赖性ClC-1通道和体外Cl−稳态。我们的初步发现表明，ClC-1 显著影响D1和D2 MSN中的电压依赖性Cl−电流。ClC-1介导的程度 HIV和阿片类药物诱导的病理学将使用功能获得、功能丧失策略进行探索， 使用电生理学、药理学和遗传学方法在体外和体内/离体证实， 细胞和分子水平。目标二。确定ClC-1调节在多大程度上有助于突触树突 阿片类药物引起的损伤和HIV诱导的Cl−稳态失调。我们预测， [Cl−]i稳态的增强在OUD/neuroHIV模型中MSN中的突触树突损伤。由于ClC-1可以是 活性依赖性Cl−进入的新来源，我们还预测阿片类药物和HIV达特通过以下途径引起神经元损伤： 这是一种复杂的机制，涉及C1 C-1调节，因此，突触去抑制。该项目将测试 阿片类药物和HIV是否通过ClC-1调节[Cl−]i稳态并引起神经元损伤。如果ClC-1是 初步证据表明，这将是我们在概念上的转变。 了解阿片类药物和艾滋病毒如何导致兴奋性毒性。

Opioid use disorder (OUD) in people infected with HIV-1 (PWH) exacerbates the pathobiology of neuroHIV and HIV-associated neurocognitive disorder (HAND) via complex mechanisms involving direct peripheral (e.g., immune suppression) and CNS (e.g., neuroinflammation, blood-brain barrier damage, and neuronal injury) effects. Although glutamatergic excitotoxicity remains the major driving force in HIV-dependent neuronal injury, emerging evidence from our lab indicates that the loss of inhibitory GABAergic control and [Cl−]i homeostasis not only contributes to a loss of inhibition, but also increases the excitatory/neurotoxic effects of glutamate at NMDA and AMPA receptors. This proposal directly tests the assumption that [Cl−]i-dependent net losses of neuronal inhibition will increase excitation and promote excitotoxic. In mature neurons, intracellular Cl− concentration ([Cl−]i) is dynamically regulated by membrane ion channels (GABAA and glycine receptors) and Cl− channels and transporters. By controlling [Cl−]i, these channels and transporters regulate the Cl− equilibrium potential (ECl) and neuronal inhibition and we have already shown the KCC2 loss-of-function in OUD/neuroHIV models leads to [Cl−]i increases, elevated ECl, and excitotoxicity. We discovered a previously unidentified a ClC-1-like voltage-dependent Cl− channel that differentially regulates the excitability of dopamine receptor D1- and D2- expressing (D1 and D2, respectively) striatal medium spiny neurons (MSNs) and is disrupted by opioids and HIV Tat. We hypothesize that opioids and HIV-1 disrupt [Cl−]i, homeostasis via a voltage-gated ClC Cl− channel resulting in synaptodendritic injury. This hypothesis will be tested in the following specific aims and if confirmed will be a conceptual shift in our understanding of how opioids and HIV contribute to excitotoxicity. Aim 1 will identify the mechanisms by which opioids and HIV dysregulate voltage- dependent ClC-1 channels and Cl− homeostasis in vitro. Our preliminary findings suggest that ClC-1 significantly affects voltage-dependent Cl− currents in D1 and D2 MSNs. The extent to which ClC-1 mediates the HIV and opioid-induced pathology will be explored using gain-of-function, loss-of-function strategies, and confirmed in vitro and in vivo/ex vivo using electrophysiologic, pharmacologic, and genetic approaches at the cell and molecular levels. Aim 2. Establish to what extent ClC-1 modulation contributes to the synaptodendritic injury caused by opioids and HIV-induced dysregulation of Cl− homeostasis. We predict that the dysregulation of [Cl−]i homeostasis amplifies synaptodendritic injury in MSNs in OUD/neuroHIV models. Since ClC-1 can be a novel source of activity-dependent Cl− entry, we also predict that opioids and HIV Tat cause neuronal injury via a complex mechanism involving ClC-1 modulation and, thus, synaptic disinhibition. This project will test whether opioids and HIV dysregulate [Cl−]i homeostasis and cause neuronal injury via ClC-1. If ClC-1 is confirmed to be that target, as preliminary evidence indicates, this will be a conceptual shift in our understanding of how opioids and HIV contribute to excitotoxicity.