Glypican-1 mediates endothelial hyperpermeability in a model of acute heart failure

The lungs are active participants in heart failure (HF). Increases in LVEDP augments pulmonary capillary pressure (PCP) that causes fluid filtration resulting in dyspnea and, ultimately, frank pulmonary edema (PE). The increase in PCP does not translate to the severity of dyspnea indicating that more than Starling Forces contribute to the clinical manifestation of HF. Acute increases in PCP activate glycocalyx-dependent mechanotransduction resulting in oxidative stress, eNOS activation and endothelial hyperpermeability. Herein we investigated if glypican-1 (Gpc-1) contributes to pressure-dependent hyperpermeability and PE in a model of acute HF. The isolated perfused lung preparation was used to simulate acute HF in male CD-1 (wild type, WT) and glypican-1 knockout (Gpc-1 -/- ) mice. Control experiments were done setting left atria pressure (P LA ) at 3cm H 2 O for 10min; acute HF was simulated by setting P LA at 10cm H 2 O for 10min. Lung edema was assessed by wet-to-dry ratio (W/D); reactive oxygen species (ROS) production and eNOS activation were assessed by lucigenin chemiluminescence, DHE fluorescence and immunoblotting, respectively. WT and Gpc-1 -/- mice had similar increase in PA pressure (from 8 to 10 mmHg). Deletion of Gpc-1 protected mice from pressure-induced PE (W/D [acute HF and control]), respectively in WT: 7.3±0.3 vs 4.9±0.3 and in Gpc-1 -/- : 4.8±0.3 vs 4.8±0.2), prevented pressure-dependent increase in ROS production in isolated membrane fraction and in total lung homogenates (15% and 80% increase in WT). eNOS activity was increased in WT (2-fold) and decreased in Gpc-1 -/- (0.5 fold) during acute HF. L-NIO inhibited edema development in WT (W/D 6.9±0.2 and 5.1±0.1 in WT and L-NIO-perfused WT, respectively). Perfusion of Gpc-1 -/- lungs with NOC9 restored the response to pressure and edema development (W/D 5.1±0.1 and 5.78±0.2 in Gpc1 -/- and NOC9-perfused Gpc-1 -/- , respectively). Collectively, these results suggest that Gpc-1 is required for pressure-induced endothelial hyperpermeability and PE in a model of acute HF.