Anti-HS3ST1 monoclonal antibody Made to order

Heparan sulfate that contains antithrombin binding sites is designated as anticoagulant heparan sulfate (HSact) since, in vitro, it dramatically enhances the neutralization of coagulation proteases by antithrombin. Endothelial cell production of HSact is controlled by the Hs3st1 gene, which encodes the rate limiting enzyme-heparan sulfate 3-O-sulfotransferase-1 (Hs3st1). It has long been proposed that levels of endothelial HSact may tightly regulate hemostatic tone. This potential in vivo role of HSact was assessed by generating Hs3st1(-/-) knockout mice. Hs3st1(-/-) and Hs3st1(+/+) mice were evaluated with a variety of methods, capable of detecting altered hemostatic tone. However, both genotypes were indistinguishable. Instead, Hs3st1(-/-) mice exhibited lethality on a specific genetic background and also showed intrauterine growth retardation. Neither phenotypes result from a gross coagulopathy. So although this enzyme produces the majority of tissue HSact, Hs3st1(-/-) mice do not show an obvious procoagulant phenotype. These results suggest that the bulk of HSact is not essential for normal hemostasis and that hemostatic tone is not tightly regulated by total levels of HSact. Moreover, the unanticipated non-thrombotic phenotypes suggest structure(s) derived from this enzyme might serve additional/alternative biologic roles.

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, Hs3sti 4 -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 Hs3stl(+/+) 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 rs16881446(G/G) genotype independently associated with the severity of coronary artery disease and atherosclerotic cardiovascular events. In primary endothelial cells, the rs16881446(G) 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. (C) 2017 Elsevier B.V. All rights reserved.