Fluvastatin inhibits up‐regulation of tissue factor expression by antiphospholipid antibodies on endothelial cells

Summary.   Background: Mechanisms of thrombosis induced by antiphospholipid (aPL) antibodies include up-regulation of tissue factor (TF) expression on endothelial cells (ECs). Statins have been shown to reduce levels of TF induced by tumor necrosis factor (TNF-α) and lipopolysaccharide (LPS) on ECs. In a recent study, fluvastatin inhibited thrombogenic and proinflammatory properties of aPL antibodies in in vivo models. The aim of this study was to determine whether fluvastatin has an effect on aPL-induced expression of TF on ECs. Methods: IgGs were purified from four patients with APS (IgG-APS) and from control sera (IgG-NHS). Cultured human umbilical vein endothelial cells (HUVEC) were treated with IgG-APS or IgG-NHS or with medium alone or with phorbol myristate acetate (PMA), as a positive control. In some experiments, cells were pretreated with fluvastatin (2.5, 5 or 10 µm) with and without mevalonate (100 µm). TF expression on HUVECs was measured by ELISA. Results: PMA and the four IgG-APS preparations increased the expression of TF on EC significantly (4.9-, 2.4-, 4.2-, 3.5- and 3.1-fold, respectively), in a dose-dependent fashion. Fluvastatin (10 µm) inhibited the effects of PMA and the four IgG-APS on TF expression by 70, 47, 65, 22 and 68%, respectively, and this effect was dose-dependent. Mevalonate (100 µm) completely abrogated the inhibitory effects of fluvastatin on TF expression induced by aPL. Conclusion: Because of the suggested pathogenic role of aPL on induction of TF on ECs, our data provide a rationale for using statins as a therapeutic tool in treatment of thrombosis in APS.