Hydroxymethylglutaryl Coenzyme A reductase (HMGCoA-red) inhibitors are cholesterol lowering drugs which display pleiotropic effects on several cell types including endothelial cells (EC). Patients with antiphospholipid syndrome (APS) are characterized by the persistent presence of antiphospholipid antibodies (aPL) and by a high incidence of recurrent thrombotic events. aPL have been demonstrated to bind and activate cultured human EC thus contributing to a prothrombotic state. We evaluated the ability of HMGCoA inhibitors to affect the EC activation induced in vitro by aPL and in particular by antibodies reacting with the PL-binding protein β2 glycoprotein I (β2GPI). Both human monoclonal IgM and polyclonal IgG anti-β2GPI antibodies were used. EC activation was evaluated as adhesion molecule (ADM) expression and cytokine production.
ADM expression was evaluated by a cell ELISA. EC were incubated with human recombinant (hr) IL-1β (50 U/ml), hr TNFα (10 ng/ml), LPS (20 ng/ml) or with human anti-β2GPI antibodies (100 μg/ml) for 4 hr for E-Selectin expression and for 20 hr for ICAM-1 evaluation. Cytokine production was investigated by using the RiboQuant™in vitro transcription assay to measure IL-6 mRNA expression. As control, EC monolayers were incubated with irrelevant monoclonal or polyclonal antibodies or medium alone. The same experiments were carried out with EC monolayers pre-incubated overnight with fluvastatin or simvastatin (1-10 μM) in the absence or presence of mevalonate (100 μM). E-Selectin specific NFκB expression was also evaluated by the gel-shift assay.
Both statins inhibited in a concentration dependent-manner the ADM expression induced by anti-β2GPI antibodies as well as those induced by the other agonists, being fluvastatin more efficient than simvastatin. Fluvastatin also down-regulated the mRNA expression specific for IL-6 and significantly inhibited E-Selectin NFκB DNA-binding. The simultaneous addition of meval-onate to fluvastatin completely prevented the drug inhibitory effect.
These data demonstrates for the first time that statins (and particularly fluvastatin) are able to inhibit an endothelial pro-adhesive and pro-inflammatory phenotype induced by different stimuli including anti-β2GPI antibodies or pro-inflammatory cytokines. Altogether these findings suggest a potential usefulness for statins in the prevention of the APS pro-atherothrombotic state.