Glypican‐1 Is a Trigger for Pulmonary Edema Development During Acute Heart Failure

Abstract

Heart Failure is a growing global epidemic with a prevalence of over 37.7 million cases. Accumulating evidence indicate that the lungs actively participate in the pathogenesis of Heart Failure and, in particular, in the development of pulmonary edema associated with acute heart failure (AHF). The molecular mechanisms by which pulmonary edema develops during AHF are not clarified but increases in pulmonary capillary pressure may play a role. Herein we sought to investigate if glypican‐1 (Gpc1), a heparan sulfate proteoglycan known to be activated by pressure, contributes to hyperpermeability and pulmonary edema during AHF. We hypothesize that Gpc1 induces pulmonary edema via eNOS uncoupling and RhoA nitration. The isolated perfused lung preparation was used to simulate AHF in male CD‐1 (wild type, WT) and glypican‐1 knockout (Gpc1KO) mice (6 weeks old). Control experiments were done setting left atria pressure (PLA) at 3cm H2O for 10 minutes; AHF was simulated by setting PLA at 10 cm H2O for 10 minutes. Lung edema was assessed by lung wet‐to‐dry ratio; heart function was assessed by echocardiography, reactive oxygen species (ROS) production was assessed by lucigenin enhanced chemiluminescence. PKCa activation, eNOS phosphorylation at T495 and Rho nitration were assessed by immunoblotting. An in vitro approach was taken to further investigate the molecular mechanisms by which increased pressure leads to endothelial hyperpermeability: human lung microvascular endothelial cells (HLMEC) were exposed or not to high hydrostatic pressure (30cm H2O) for 10 minutes and analysis of activation of PKC‐eNOS‐RhoA axis was performed by immunoblotting. WT and Gpc1KO mice showed similar ejection fraction and increase in pulmonary artery pressure. Deletion of Gpc1 protected mice from pulmonary edema associated with AHF and prevented increase on ROS production. Inhibition of eNOS with L‐NIO mitigated pulmonary edema during AHF in WT mice. NOC‐9, a NO donor, restored the ability of GPC1KO lungs to develop edema during AHF. Moreover, WT mice showed increased eNOS phosphorylation at T495, PKCa activation and RhoA nitration during AHF, effects not seen in Gpc1KO. In vitro, increased hydrostatic pressure induced activation of the same pathways as seen in the in situ model. Taken together, these results suggest that activation of Gpc1 leads to eNOS uncoupling and RhoA nitration that results in endothelial hyperpermeability and pulmonary edema during AHF. These data evidence the lung endothelium as an active player during AHF and glypican‐1 as a gatekeeper of barrier function.Support or Funding InformationP01 HL134610 (SMB) and funds from the Department of Anesthesiology, College of Medicine, University of Arizona, Tucson and the Department of Anesthesiology, College of Medicine, University of Illinois at Chicago.