Endothelial PHD2 in hypertensive vascular remodeling

摘要：动脉僵硬是高血压的中心特征，对疾病有重大影响。 病因和结果。到目前为止，还没有治愈高血压动脉僵硬的方法。因此，当务之急是 以确定可以降低高血压动脉僵硬的潜在治疗靶点。新出现的证据 提示周细胞是血管生成和血管重塑的新靶点。周细胞是一种 可分化为成骨细胞的间充质干细胞亚群，血管通畅 肌肉细胞(VSMCs)和成纤维细胞。周细胞通过周细胞成纤维细胞促进纤维化形成 过渡(PFT)。周细胞也被证明在动脉重塑区域分化为血管平滑肌细胞。 在内心深处。我们最近的研究发现，氧传感器脯氨酸羟基酶-2(PHD2)的缺失 内皮导致周细胞过度募集和动脉僵硬，并加剧 血管紧张素II(Ang-II)诱导的高血压。内皮细胞PHD2基因敲除引起的不平衡 精氨酸酶-2/eNOS偏向于精氨酸酶-2。此外，内皮细胞PHD2的敲除显著 主动脉中成骨分化标志物(SOX9、BMP2和骨桥蛋白)增加并促进 VSMC钙化。利用NG2周细胞示踪报告基因NG2DsRedBAC小鼠的初步研究 进一步提示NG2+周细胞在Ang-II介导血管重塑中的重要作用。基于 我们的发现，我们假设在EC中PHD2的失活增加了动脉僵硬和 精氨酸酶-2/eNOS失衡与周细胞分化相关的高血压机制 通过HIF-2α-PFKFB3信号通路向血管平滑肌细胞、成骨细胞和成纤维细胞分化。两个具体目标 将建议测试：目标1：确定内皮细胞PHD2 调节动脉僵硬，关注失衡的精氨酸酶-2/eNOS。我们将决定：(I) 内皮细胞PHD2缺失是否通过HIF-2α-PFKFB3导致精氨酸酶-2/eNOS失衡 信号通路，(Ii)药物阻断缺氧诱导因子-2α是否具有临床相关性和高度相关性 特异性抑制剂PT2385抑制PFKFB3表达，恢复精氨酸酶-2/eNOS平衡，并 降低Ang-II诱导的PHD2ECKO小鼠动脉僵直；以及(3)精氨酸酶-2基因敲除 减少PHD2ECKO小鼠的血管重塑和动脉僵硬。目标2：确定PHD2的作用- PFKFB3在介导周细胞分化和高血压动脉硬化中的作用。使用周细胞示踪法 记者将NG2DsRedBAC(TG)小鼠与PHD2ECKO小鼠杂交，我们将测试是否抑制 PFKFB3抑制周细胞的成骨分化，减少血管钙化。我们会 进一步确定PHD2的药理激活或抑制PFKFB3是否减弱血管紧张素转换酶的活性 II诱导的周细胞-成纤维细胞/VSMC转化、动脉僵硬和高血压血管重构。 我们的研究对于理解周细胞在血管僵硬中的作用具有临床翻译意义。

Summary: Arterial stiffness is the center feature of hypertension and has significant impact upon disease etiology and outcomes. So far, there is no cure for hypertensive arterial stiffness. Therefore, it is urgent to identify potential therapeutic targets that can reduce hypertensive arterial stiffness. Emerging evidence indicates that pericyte is a novel target of angiogenesis and vascular remodeling. Pericytes are a subpopulation of mesenchymal stem cells which can differentiate into osteoblasts, vascular smooth muscle cells (VSMCs) and fibroblasts. Pericytes promotes fibrosis formation via pericyte-(myo)-fibroblast transition (PFT). Pericyte also has been shown to differentiate into VSMCs at arterial remodeling zones in the heart. Our recent study found that deletion of oxygen sensor prolyl hydroxylase-2 (PHD2) in the endothelium resulted in excessive pericyte recruitment and arterial stiffness, and exacerbation of angiotensin II (Ang-II)-induced hypertension. Knockout of endothelial PHD2 caused an imbalanced arginase-2/eNOS favoring in arginase-2. Furthermore, knockout of endothelial PHD2 significantly increased osteogenic differentiation markers (SOX9, BMP2 and osteopontin) in the aorta and promoted VSMC calcification. Using NG2 pericyte tracing reporter NG2DsRedBAC mice, our preliminary study further suggested an important role of NG2+ pericyte in Ang-II mediating vascular remodeling. Based on our findings, we hypothesize that deactivation of PHD2 in EC enhances arterial stiffness and hypertension by the mechanisms involving an imbalanced arginase-2/eNOS and pericyte differentiation into VSMCs, osteogenic cells and fibroblasts via HIF-2α-PFKFB3 signaling pathway. Two specific aims will be proposed to test: Aim 1: To define the molecular mechanisms by which endothelial PHD2 regulates arterial stiffness with a focus on an imbalanced arginase-2/eNOS. We will determine: (i) whether deficiency of endothelial PHD2 induces an imbalanced arginase-2/eNOS via HIF-2α-PFKFB3 signaling pathway, (ii) whether pharmacologic blockade of HIF-2α using a clinic relevant and highly specific inhibitor PT2385 attenuates PFKFB3 expression, restores arginase-2/eNOS balances and reduces Ang-II-induced arterial stiffness in PHD2ECKO mice; and (3) whether knockout of arginase-2 reduces vascular remodeling and arterial stiffness in PHD2ECKO mice. Aim 2: To define the role of PHD2- PFKFB3 in mediating pericyte differentiation and hypertensive arterial stiffness. Using pericyte tracing reporter NG2DsRedBAC (Tg) mice crossing with PHD2ECKO mice, we will test whether inhibition of PFKFB3 attenuates osteogenic differentiation of pericytes, and reduces vascular calcification. We will further determine whether pharmacological activation of PHD2 or inhibition of PFKFB3 attenuates Ang- II-induced pericyte-fibroblast/VSMC transition, arterial stiffness and hypertensive vascular remodeling. Our study has clinical translational significance for the understanding of pericytes in vascular stiffness.