Selective inhibition of formyl-methionyl-leucyl- phenylalanine (fMLF)-dependent superoxide generation in neutrophils by pravastatin, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase

It has been shown previously that inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, such as compactin, lovastatin, and pravastatin, block cholesterol synthesis, suppress lymphocyte functions, and beneficially affect atherogenesis. Recently, it was reported that compactin and lovastatin inhibit the respiratory burst of DMSO-differentiated HL-60 cells, an effect reversed by mevalonic acid. The mode of action of these inhibitors in this role is not understood fully. Thus, we studied the mechanism of inhibition of neutrophil superoxide (O-2(.-)) generation by pravastatin and found that pravastatin at 0.5 mM inhibited the receptor-mediated tyrosine kinase (TK)-dependent pathway of O-2(.-) generation and also luminol chemiluminescence but not the protein kinase C (PKC)-dependent or the TK- and PKC-independent pathways of O-2(.-) generation in neutrophils. Pravastatin also inhibited the tumor necrosis factor-alpha- and formyl-methionyl-leucyl-phenylalanine-induced phosphorylation of a tyrosine of a 115-kDa protein. These effects were not reversed by mevalonate. From these results it is concluded that pravastatin inhibited receptor-mediated O-2(.-) generation by decreasing tyrosine phosphorylation but not by inhibiting the formation of an intermediate in the biosynthesis of cholesterol. (C) 1999 Elsevier Science Inc.