Heparanase-2 protects from LPS-mediated endothelial injury by inhibiting TLR4 signalling

• Published in: Scientific reports 2019-09, Vol.9 (1), p.13591-13, Article 13591
• Main Authors: Kiyan, Yulia, Tkachuk, Sergey, Kurselis, Kestutis, Shushakova, Nelli, Stahl, Klaus, Dawodu, Damilola, Kiyan, Roman, Chichkov, Boris, Haller, Hermann
• Format: Article
• Language: English
• Subjects: 631/45/221; 631/80/86; Animals; Capillaries; CD14 antigen; Cell activation; Disease Models, Animal; Endothelial cells; Endothelial Cells - cytology; Endothelial Cells - metabolism; Glucuronidase - blood; Glucuronidase - genetics; Glucuronidase - metabolism; Glycocalyx - metabolism; Heparan sulfate; Heparitin Sulfate - metabolism; Humanities and Social Sciences; Humans; Inflammation; Interleukin 6; Intravenous administration; Kidneys; Lipopolysaccharides; Lipopolysaccharides - adverse effects; Male; Mice; Microfluidic Analytical Techniques; Microfluidics; Microvasculature; multidisciplinary; Science; Sepsis; Sepsis - chemically induced; Sepsis - metabolism; Signal Transduction; Sulfates; TLR4 protein; Toll-Like Receptor 4 - metabolism; Toll-like receptors; Tumor necrosis factor-α
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-50068-5

The endothelial glycocalyx and its regulated shedding are important to vascular health. Endo-β-D-glucuronidase heparanase-1 (HPSE1) is the only enzyme that can shed heparan sulfate. However, the mechanisms are not well understood. We show that HPSE1 activity aggravated Toll-like receptor 4 (TLR4)-mediated response of endothelial cells to LPS. On the contrary, overexpression of its endogenous inhibitor, heparanase-2 (HPSE2) was protective. The microfluidic chip flow model confirmed that HPSE2 prevented heparan sulfate shedding by HPSE1. Furthermore, heparan sulfate did not interfere with cluster of differentiation-14 (CD14)-dependent LPS binding, but instead reduced the presentation of the LPS to TLR4. HPSE2 reduced LPS-mediated TLR4 activation, subsequent cell signalling, and cytokine expression. HPSE2-overexpressing endothelial cells remained protected against LPS-mediated loss of cell-cell contacts. In vivo , expression of HPSE2 in plasma and kidney medullary capillaries was decreased in mouse sepsis model. We next applied purified HPSE2 in mice and observed decreases in TNFα and IL-6 plasma concentrations after intravenous LPS injections. Our data demonstrate the important role of heparan sulfate and the glycocalyx in endothelial cell activation and suggest a protective role of HPSE2 in microvascular inflammation. HPSE2 offers new options for protection against HPSE1-mediated endothelial damage and preventing microvascular disease.