Mevalonate-Dependent Inhibition of Transendothelial Migration and Chemotaxis of Human Peripheral Blood Neutrophils by Pravastatin

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Abstract
Pravastatin, a hydrophilic inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, has been reported to beneficially affect atherogenesis, plaque stability, and transient myocardial ischemia in significant coronary artery disease by influencing lipid metabolism and by intracellular signaling via mevalonate pathway products other than cholesterol. Leukocytes are implicated to play a pathophysiological role in these events. We were interested in finding out whether pravastatin could affect transendothelial migration (TEM), chemotaxis, and respiratory burst activity of the neutrophil ex vivo. In addition, effects on monocyte and T-lymphocyte chemotaxis were tested. For TEM assays, monolayers of human umbilical vein endothelial cells (HUVECs) were grown to confluence on polycarbonate filters bearing 5-μm pores in Transwell (Costar) culture plate inserts. Chemotaxis experiments were performed using modified Boyden chambers with cellulose nitrate micropore filters. Respiratory burst activity was measured fluorometrically. Treatment of neutrophils and monocytes with pravastatin at 2 to 200 μmol/L and 10 to 1000 μmol/L, respectively, significantly decreased chemotaxis triggered by fMet-Leu-Phe. This effect was abolished in the presence of mevalonic acid (500 μmol/L); no effect of pravastatin was seen on T-lymphocyte chemotaxis triggered by interleukin-8. Preincubation of neutrophils with pravastatin (200 μmol/L) also resulted in a significant reduction in the number of neutrophils that transmigrated a tumor necrosis factor–stimulated or lipopolysaccharide-stimulated HUVEC monolayer. At none of the concentrations tested (2 pmol/L to 200 μmol/L) did pravastatin affect neutrophil respiratory burst activity. We conclude that pravastatin may alter monocyte chemotaxis and neutrophil-endothelial interactions in migratory responses at concentrations obtained in vivo with cholesterol-lowering doses.