HS3ST1 genotype regulates antithrombin's inflammomodulatory tone and associates with atherosclerosis

Abstract

The HS3ST1 gene controls endothelial cell production of HSAT+ – a form of heparan sulfate containing a specific pentasaccharide motif that binds the anticoagulant protein antithrombin (AT). HSAT+ has long been thought to act as an endogenous anticoagulant; however, coagulation was normal in Hs3st1−/− mice that have greatly reduced HSAT+ (HajMohammadi et al., 2003). This finding indicates that HSAT+ is not essential for AT’s anticoagulant activity. To determine if HSAT+ is involved in AT’s poorly understood inflammomodulatory activities, Hs3st1−/− and Hs3st1+/+ mice were subjected to a model of acute septic shock. Compared with Hs3st1+/+ mice, Hs3st1−/− mice were more susceptible to LPS-induced death due to an increased sensitivity to TNF. For Hs3st1+/+ mice, AT treatment reduced LPS-lethality, reduced leukocyte firm adhesion to endothelial cells, and dilated isolated coronary arterioles. Conversely, for Hs3st1−/− mice, AT induced the opposite effects. Thus, in the context of acute inflammation, HSAT+ selectively mediates AT’s anti-inflammatory activity; in the absence of HSAT+, AT’s pro-inflammatory effects predominate. To explore if the anti-inflammatory action of HSAT+ also protects against a chronic vascular-inflammatory disease, atherosclerosis, we conducted a human candidate-gene association study on >2000 coronary catheterization patients. Bioinformatic analysis of the HS3ST1 gene identified an intronic SNP, rs16881446, in a putative transcriptional regulatory region. The rs16881446G/G genotype independently associated with the severity of coronary artery disease and atherosclerotic cardiovascular events. In primary endothelial cells, the rs16881446G allele associated with reduced HS3ST1 expression. Together with the mouse data, this leads us to conclude that the HS3ST1 gene is required for AT’s anti-inflammatory activity that appears to protect against acute and chronic inflammatory disorders.

The heparan sulfate proteoglycan grip on hyperlipidemia and atherosclerosis

“…Inactivation of HS3ST1 in mice ( Hs3st1 −/− ), an enzyme involved in installation of sulfate groups at C3 of N -sulfoglucosamine residues in HS and formation of the antithrombin binding site (Fig. 1), had a similar effect after LPS-induction of leukocyte rolling [142]. These findings suggest that antithrombin binding to HS can compete or prevent proper leukocyte extravasion.…”

“…Reduced sulfation of endothelial HS in Ndst1 fl/fl Tie2Cre + mice results in increased rolling velocity of neutrophils and reduced firm adhesion to the endothelium in cremaster muscle venules [135, 142]. Inactivation of HS3ST1 in mice ( Hs3st1 −/− ), an enzyme involved in installation of sulfate groups at C3 of N -sulfoglucosamine residues in HS and formation of the antithrombin binding site (Fig.…”

“…These findings suggest that antithrombin binding to HS can compete or prevent proper leukocyte extravasion. Although antithrombin binding sites are typically abluminal in normal tissues, binding was prominent across the endothelium at atherosclerosis prone sites [142]. Initial attempts to study this interaction in hypercholesterolemic mice failed due to the embryonic lethality of Hs3st1 deficiency, but this question can now be addressed by backcrossing the strain onto a pure C57Bl/6 background [143] (Esko et al, unpublished).…”

“…Analysis of the human HS3ST1 gene showed that SNP rs16881446 G/G in the HS3ST1 gene is associated with reduced HS3ST1 mRNA expression in human primary endothelial cells and is overrepresented in a population with more severe coronary artery disease (Fig. 5) [142]. These findings are quite provocative and suggest that subtle changes in endothelial HS composition could play a role in atherogenesis [46, 134–137].…”

Investigating global gene expression changes in a murine model of cherubism

“…Facilitating the remodeling of heparan sulfate, several members of the 3-O sulfotransferase family were up regulated including Hs3st1 (Log 2 Fold 2.37), Hs3st3a1 (Log 2 Fold 1.77), Hs3st3b1 (Log 2 Fold 1.69). Through the modification of heparan, these enzymes can regulate processes such as coagulation and epithelial to mesenchymal transition [83,84]. Thrombomodulin (Thbd; Log 2 Fold 1.07), which is modestly upregulated has important roles in anti-coagulation and anti-in-flammation through direct binding of thrombin and also through the activation of Protein C [85][86][87].…”