Effect of heparanase inhibitor on tissue factor overexpression in platelets and endothelial cells induced by anti-β2-GPI antibodies

Background Anti-phospholipid syndrome (APS) is characterized by arterial and/or venous thrombosis and pregnancy morbidity associated with the presence of anti-phospholipid antibodies. Thrombosis may be the result of a hypercoagulable state related to activation of endothelial cells and platelets by anti-beta 2-glycoprotein I (beta 2-GPI) antibodies. Anti-beta 2-GPI antibodies induce a proinflammatory and procoagulant phenotype in these cells that, after activation, express tissue factor (TF), the major initiator of the clotting cascade, playing a role in thrombotic manifestations. Moreover, TF expression may also be induced by heparanase, an endo-beta-D-glucuronidase, that generates heparan sulfate fragments, regulating inflammatory responses. Objectives In this study we analyzed, in human platelets and endothelial cells, the effect of a new symmetrical 2-aminophenyl-benzazolyl-5-acetate derivative (RDS3337), able to inhibit heparanase activity, on signal transduction pathways leading to TF expression triggered by anti-beta 2-GPI. Methods Platelets and endothelial cells were incubated with affinity purified anti-beta 2-GPI after pretreatment with RDS3337. Cell lysates were analyzed for phospho-interleukin-1 receptor-associated kinase 1 (IRAK1), phospho-p65 nuclear factor kappa B (NF-kappa B) and TF by western blot. In addition, platelet activation and secretion by ATP release dosage were evaluated. Results IRAK phosphorylation and consequent NF-kappa B activation, as well as TF expression triggered by anti-beta 2-GPI treatment were significantly prevented by previous pretreatment with RDS3337. In the same vein, pretreatment with RDS3337 prevented platelet aggregation and ATP release triggered by anti-beta 2-GPI antibodies. Conclusion These findings support the view of heparanase involvement in a prothrombotic state related to APS syndrome, suggesting a novel target to regulate overexpression of procoagulant protein(s).

Automated summary

Anti-phospholipid syndrome (APS) is associated with arterial and venous thrombosis and pregnancy morbidity due to the presence of anti-phospholipid antibodies. This study found that the novel drug RDS3337 can inhibit Heparanase activity, preventing TF expression triggered by anti-beta 2-GPI and reducing platelet aggregation and ATP release. These findings suggest a potential new target for regulating procoagulant proteins in APS.