Augusta University Vascular Biology Center, Augusta, Georgia.
Department of Medicine, University of Colorado Denver, Aurora, Colorado.
Am J Physiol Cell Physiol. 2020 Jul 1;319(1):C183-C193. doi: 10.1152/ajpcell.00505.2019. Epub 2020 May 20.
The vasa vasorum (VV), the microvascular network around large vessels, has been recognized as an important contributor to the pathological vascular remodeling in cardiovascular diseases. In bovine and rat models of hypoxic pulmonary hypertension (PH), we have previously shown that chronic hypoxia profoundly increased pulmonary artery (PA) VV permeability, associated with infiltration of inflammatory and progenitor cells in the arterial wall, perivascular inflammation, and structural vascular remodeling. Extracellular adenosine was shown to exhibit a barrier-protective effect on VV endothelial cells (VVEC) via cAMP-independent mechanisms, which involved adenosine A1 receptor-mediated activation of Gi-phosphoinositide 3-kinase-Akt pathway and actin cytoskeleton remodeling. Using VVEC isolated from the adventitia of calf PA, in this study we investigated in more detail the mechanisms linking Gi activation to downstream barrier protection pathways. Using a small-interference RNA (siRNA) technique and transendothelial electrical resistance assay, we found that the adaptor protein, engulfment and cell motility 1 (ELMO1), the tyrosine phosphatase Src homology region 2 domain-containing phosphatase-2, and atypical Gi- and Rac1-mediated protein kinase A activation are implicated in VVEC barrier enhancement. In contrast, the actin-interacting GTP-binding protein, girdin, and the p21-activated kinase 1 downstream target, LIM kinase, are not involved in this response. In addition, adenosine-dependent cytoskeletal rearrangement involves activation of cofilin and inactivation of ezrin-radixin-moesin regulatory cytoskeletal proteins, consistent with a barrier-protective mechanism. Collectively, our data indicate that targeting adenosine receptors and downstream barrier-protective pathways in VVEC may have a potential translational significance in developing pharmacological approach for the VV barrier protection in PH.
血管外腔（VV）是围绕大血管的微血管网络，已被认为是心血管疾病中病理性血管重塑的重要贡献者。在牛和大鼠低氧性肺动脉高压（PH）模型中，我们之前已经表明，慢性低氧会显著增加肺动脉（PA）VV 的通透性，与动脉壁中炎症和祖细胞的浸润、血管周围炎症和结构血管重塑有关。已经表明细胞外腺苷通过 cAMP 非依赖性机制对 VV 内皮细胞（VVEC）表现出屏障保护作用，该机制涉及腺苷 A1 受体介导的 Gi-磷酰肌醇 3-激酶-Akt 途径和肌动蛋白细胞骨架重塑的激活。使用从小牛 PA 外膜分离的 VVEC，在这项研究中，我们更详细地研究了将 Gi 激活与下游屏障保护途径联系起来的机制。使用小干扰 RNA（siRNA）技术和跨内皮电阻测定法，我们发现衔接蛋白，吞噬和细胞运动 1（ELMO1），Src 同源区 2 域包含磷酸酶-2 的酪氨酸磷酸酶，以及非典型 Gi 和 Rac1 介导的蛋白激酶 A 激活与 VVEC 屏障增强有关。相比之下，肌动蛋白相互作用的 GTP 结合蛋白，girdin，和 p21 激活激酶 1 的下游靶标，LIM 激酶，不参与此反应。此外，腺苷依赖性细胞骨架重排涉及丝切蛋白和 ezrin-radixin-moesin 调节细胞骨架蛋白的失活，与屏障保护机制一致。总之，我们的数据表明，靶向 VVEC 中的腺苷受体和下游屏障保护途径可能在开发用于 PH 中 VV 屏障保护的药理学方法方面具有潜在的转化意义。
