Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA335

Poster Communications

Influence of high-density-lipoproteins on the endothelial glycocalyx

B. Hesse1,2, P. Kümpers1, K. Kusche-Vihrog2, J. Nofer3, H. Pavenstädt1, W. A. Linke2, A. Lukasz1

1. Medicine D, Division of General Internal Medicine, Nephrology, and Rheumatology, University Hospital Münster, Münster, Germany. 2. Institute of Physiology 2, Münster, Germany. 3. Center for Laboratory Medicine, Münster, Germany.

B. Hesse (1,2), P. Kümpers (1), K. Kusche-Vihrog (2), J.-R. Nofer (3), H. Pavenstädt (1), W. Linke (2), A. Lukasz (1) Department of Medicine D, Division of General Internal Medicine, Nephrology, and Rheumatology, University Hospital Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany Institute of Physiology II, Robert-Koch-Straße 27b, 48149 Münster, University of Münster, Germany Center for Laboratory Medicine, University Hospital Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany The endothelial glycocalyx (eGC) is a negatively charged, carbohydrate-rich layer that lines the luminal side of the vascular endothelium. As the primary physical barrier between blood and the vessel, the eGC serves as a firewall against endothelial hyperpermeability and leukocyte recruitment in systemic inflammatory diseases. High-density lipoproteins (HDL) are known to be atheroprotective by amongst others reducing endothelial inflammation through inhibiting cell apoptosis and enhancing availability of nitric oxide. If HDL exerts eGC-protecting effects as well is currently unknown. Here we hypothesize that HDL or specific HDL-bound factors such like Sphingosin-1-phosphate (S1P) may improve eGC integrity. To study the influence of HDL on eGC integrity, we determined thickness and stiffness of the eGC in endothelial cells (EA.hy926) using live-cell atomic force microscopy (AFM). Additionally, immunofluorescence intensities of main constituents of the eGC such as heparan sulphate were measured with confocal microscopy. To study the potential eGC-protective effect of HDL and S1P, endothelial cells (EA.hy926) were incubated with physiological concentration of HDL (0.5 mg/ml) or S1P (1 µM). HDL used for in-vitro incubation experiments was isolated from serum of apparently healthy volunteers with ultra-centrifugation. To identify potentially involved S1P-receptors we coincubated EA.hy926 with S1P and the specific S1P1 and -3 receptor (S1PR) inhibitor(VPC, 10 µM). Incubation of endothelial cells with HDL or S1P alone is sufficient to maintain eGC integrity compared to control conditions (serum-free buffer) (Figure 1). Accordingly, immunofluorescence intensity of heparan sulphate is preserved by HDL or S1P, whereas immunofluorescence was markedly decreased by control conditions. However, the protective effect of HDL or S1P was completely abolished by addition of W146. These results demonstrate that HDL from healthy patients is sufficient to maintain the eGC. EGC-strengthening effects may be mediated through HDL-bound S1P. Our data suggest that S1P mediates its eGC-enhancing effects via S1P1 or -3R. S1P concentration is known to be reduced in systemic inflammatory diseases like diabetes mellitus. The eGC-protective role of S1P needs to be addressed in further studies.

Where applicable, experiments conform with Society ethical requirements