Investigating the Role of HIV X4 Variants in Pulmonary Vascular Remodeling and Pulmonary Hypertension in Humanized Mice

 描述(由申请人提供)： 肺动脉高压(PAH)是一种危及生命的疾病，即使接受了抗逆转录病毒治疗，这种疾病在艾滋病毒感染者中也明显更常见。HIV如何在HIV-PAH的病理生理学中起作用仍不清楚。HIV蛋白是主要的可疑因素，但这些蛋白影响血管重塑的确切机制尚不清楚。Tat、Nef和gp120等HIV蛋白可能在HIV-PAH的发病机制中发挥作用。HIV gp120与CD4相互作用后与CCR5(R5)或CXCR4(X4)趋化因子受体结合。在PAH动物模型中，CCR5或CXCR4与配体的相互作用促进炎症，导致血管重构。我们有初步证据表明，患有PAH的HIV感染者拥有显著更多的利用CXCR4的HIV变种(X4病毒)。虽然CCR5信号导致SIV感染的猕猴出现PAH，但我们在HIV感染者中发现X4病毒与PAH之间的关联，这使我们特别关注X4病毒对HIV-PAH的贡献。此外，我们还发现，与R5 gp120相比，HIV-X4可诱导肺内皮细胞血管收缩花生四烯酸5-脂氧合酶(ALOX-5)基因的过度表达。因此，我们的研究发现X4病毒在HIV-PAH的病理生理学中具有潜在的作用。在HIV X4病毒存在的情况下，CXCR4信号是否会导致PAH仍不清楚。我们推测HIV X4通过CXCR4信号途径诱导慢性炎症，导致肺血管重塑和PAH。我们认为，为了推动这一领域的发展，必须首先验证艾滋病毒-多环芳烃模型，并审查 X4病毒对肺血管系统的影响。不幸的是，除了非人类灵长类动物外，还没有HIV-PAH动物模型来概括这种疾病的自然历史。为了验证我们的假设，我们建议验证最先进的植入人骨髓、淋巴和胸腺的小鼠(HU-BLT)作为HIV-PAH的模型。方法：我们建议：1)研究HIV感染的Hu-BLT小鼠的肺血管重构和右室肥厚；2)研究CXCR4信号在体内和体外暴露于HIV X4病毒的肺血管细胞中的功能作用。意义和创新：这些研究具有重要意义，因为我们的模型将加速对CXCR4信号通路的机制研究，这可能允许对其他形式的PAH，例如特发性和低氧诱导的PAH进行趋同的机制解释，并将有助于解释为什么HIV患者更容易发生影响肾脏和大脑等其他末端器官的血管疾病。此外，我们提出了CXCR4-利用HIV在PAH中发挥作用的创新理论概念，并率先在Hu-BLT小鼠中获得了对HIV相关肺血管病变的见解。

 DESCRIPTION (provided by applicant): Pulmonary Arterial Hypertension (PAH) is a life-threatening disease that is significantly more frequent in HIV-infected individuals even with antiretroviral therapy. How HIV contributes to the pathophysiology of HIV-PAH remains unknown. HIV proteins are the main suspects but the exact mechanisms whereby these proteins influence vascular remodeling are unknown. HIV proteins like Tat, Nef and gp120 likely play a role in the pathogenesis of HIV-PAH. HIV gp120 binds to either CCR5 (R5) or CXCR4 (X4) chemokine receptors after interacting with CD4. Either CCR5 or CXCR4-ligand interactions promote inflammation leading to vascular remodeling in animal models of PAH. We have preliminary evidence that HIV-infected individuals with PAH harbor significantly more CXCR4-utilizing HIV variants (X4 viruses). While CCR5 signaling leads to PAH in SIV-infected macaques, our finding of an association between X4 viruses and PAH in HIV-infected individuals lead us to focus specifically on the contribution of X4 viruses to HIV-PAH. Furthermore, we found that HIV-X4, compared to R5 gp120, induces over-expression of the vasoconstrictive arachidonate 5- lipoxygenase (ALOX-5) gene in pulmonary endothelial cells. Hence, our research has uncovered X4 viruses as potential agents in the pathophysiology of HIV-PAH. Whether CXCR4 signaling in the presence of HIV X4 virus leads to PAH remains elusive. We hypothesize that HIV X4 induces chronic inflammation leading to pulmonary vascular remodeling and PAH via CXCR4 signaling. We believe that, in order to advance this field, it is imperative to first validate a model for HIV-PAH and examine the impact of X4 viruses on the pulmonary vasculature. Unfortunately, other than non-human primates, there is no HIV-PAH animal model that recapitulates the natural history of this disease. To test our hypothesis, we propose to validate the state-of-the- art mice engrafted with human Bone marrow, Lymph node and Thymus (hu-BLT) as model for HIV-PAH. APPROACH: We propose to: 1) characterize pulmonary vascular remodeling and right ventricular hypertrophy in HIV-infected hu-BLT mice, and 2) examine the functional role of CXCR4 signaling in pulmonary vascular cells exposed to HIV X4 virus in vivo and in vitro. SIGNIFICANCE AND INNOVATION: These studies are significant because our model will accelerate mechanistic studies on the CXCR4 signaling pathway that may allow for convergent mechanistic explanations for other forms of PAH, e.g. idiopathic and hypoxia-induced PAH, and will help explain why HIV patients are more prone to vascular diseases affecting other end-organs like kidneys and brain. In addition, we bring the innovative theoretical concept that CXCR4-utilizing HIV plays a role in PAH and pioneer the hu-BLT mouse to gain insights into HIV-associated pulmonary vasculopathy.