Adenosine A1 receptors promote vasa vasorum endothelial cell barrier integrity via Gi and Akt-dependent actin cytoskeleton remodeling

• Published in: PloS one Vol. 8; no. 4; p. e59733
• Main Authors: Umapathy, Siddaramappa Nagavedi, Siddaramappa Umapathy, Nagavedi, Kaczmarek, Elzbieta, Fatteh, Nooreen, Burns, Nana, Lucas, Rudolf, Stenmark, Kurt R, Verin, Alexander D, Gerasimovskaya, Evgenia V
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 16.04.2013; Public Library of Science (PLoS)
• Subjects: 1-Phosphatidylinositol 3-kinase; Actin; Actin Cytoskeleton - drug effects; Actin Cytoskeleton - metabolism; Adenosine; Adenosine A1 receptors; AKT protein; Angiogenesis; Animals; Arteries; Biology; Blood cells; Blood circulation; Calves; Cattle; Chromones - pharmacology; Cytoskeleton; Endothelial cells; Endothelial Cells - drug effects; Endothelial Cells - metabolism; Endothelium; Gastroenterology; GTP-Binding Protein alpha Subunits, Gi-Go - metabolism; Hypertension; Hypoxia; Inflammation; Integrity; Kinases; Macromolecules; Male; Medicine; Molecular modelling; Morpholines - pharmacology; Neonates; Oxadiazoles - pharmacology; Pediatrics; Permeability; Pertussis; Pertussis toxin; Physiology; Polymerase chain reaction; Polymerization; Proteins; Proto-Oncogene Proteins c-akt - metabolism; Pulmonary arteries; Pulmonary artery; Pulmonary hypertension; Receptor, Adenosine A1 - metabolism; Receptors; Reverse transcription; Rodents; siRNA; Studies; Thickening; Tumor Necrosis Factor-alpha - pharmacology; Tumor necrosis factor-TNF; Tumor necrosis factor-α; Vasa Vasorum - cytology; Vasa Vasorum - drug effects; Vasa Vasorum - metabolism; Veins & arteries; United States > US; Colorado; Georgia
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0059733

In a neonatal model of hypoxic pulmonary hypertension, a dramatic pulmonary artery adventitial thickening, accumulation of inflammatory cells in the adventitial compartment, and angiogenic expansion of the vasa vasorum microcirculatory network are observed. These pathophysiological responses suggest that rapidly proliferating vasa vasorum endothelial cells (VVEC) may exhibit increased permeability for circulating blood cells and macromolecules. However, the molecular mechanisms underlying these observations remain unexplored. Some reports implicated extracellular adenosine in the regulation of vascular permeability under hypoxic and inflammatory conditions. Thus, we aimed to determine the role of adenosine in barrier regulation of VVEC isolated from the pulmonary arteries of normoxic (VVEC-Co) or chronically hypoxic (VVEC-Hyp) neonatal calves. We demonstrate via a transendothelial electrical resistance measurement that exogenous adenosine significantly enhanced the barrier function in VVEC-Co and, to a lesser extent, in VVEC-Hyp. Our data from a quantitative reverse transcription polymerase chain reaction show that both VVEC-Co and VVEC-Hyp express all four adenosine receptors (A1, A2A, A2B, and A3), with the highest expression level of A1 receptors (A1Rs). However, A1R expression was significantly lower in VVEC-Hyp compared to VVEC-Co. By using an A1R-specific agonist/antagonist and siRNA, we demonstrate that A1Rs are mostly responsible for adenosine-induced enhancement in barrier function. Adenosine-induced barrier integrity enhancement was attenuated by pretreatment of VVEC with pertussis toxin and GSK690693 or LY294002, suggesting the involvement of Gi proteins and the PI3K-Akt pathway. Moreover, we reveal a critical role of actin cytoskeleton in VVEC barrier regulation by using specific inhibitors of actin and microtubule polymerization. Further, we show that adenosine pretreatment blocked the tumor necrosis factor alpha (TNF-α)-induced permeability in VVEC-Co, validating its anti-inflammatory effects. We demonstrate for the first time that stimulation of A1Rs enhances the barrier function in VVEC by activation of the Gi/PI3K/Akt pathway and remodeling of actin microfilament.