A 4-trifluoromethyl derivative of salicylate, triflusal, stimulates nitricoxide production by human neutrophils: role in platelet function

Background The thrombotic process is a multicellular phenomenon in which no t only platelets but also neutrophils are involved. Recent in vitro studies performed in our laboratory have demonstrated that triflusal, a 4-trifluor omethyl derivative of salicylate, reduced platelet aggregation not only by inhibiting thromboxane A(2) production but also by stimulating nitric oxide (NO) generation by neutrophils. The aim of the present study was to evalua te whether oral treatment of healthy Volunteers with triflusal could modify the ability of their neutrophils to produce NO and to test the role of the NO released by neutrophils in the modulation of ADP-induced platelet aggre gation and ct-granule secretion. Methods The study was performed in 12 healthy volunteers who were orally tr eated with triflusal (600 mg day(-1)) for 5 days. Flow cytometric detection of platelet surface expression of P-selectin was used as a measure of the ability of platelets to release the contents of their ct-granules. Results After treatment with triflusal, there was an increase in NO product ion by neutrophils and an increase in endothelial nitric oxide synthase (eN OS) protein expression in neutrophils. A potentiation of the inhibition of platelet aggregation by neutrophils was reversed by incubating neutrophils with both an L-arginine antagonist, N-G-nitro-L-arginine methyl ester (L-NA ME) and an NO scavenger, 2-(4-carboxyphenyl)-4,4,5,5 tetramethylimidazoline 1-oxyl 3-oxide (C-PTIO). A slight decrease in P-selectin surface expressio n on platelets was found which was not modified by the presence of neutroph ils and therefore by the neutrophil-derived NO. Exogenous NO released by so dium nitroprusside dose-dependently inhibited both ADP-stimulated ct-granul e secretion and platelet aggregation. Therefore, platelet aggregation showe d a greater sensitivity to be inhibited by exogenous NO than P-selectin exp ression. Conclusion Oral treatment of healthy volunteers with triflusal stimulated N O production and eNOS protein expression in their neutrophils. After triflu sal treatment, the neutrophils demonstrated a higher ability to prevent ADP -induced platelet aggregation. However, the neutrophils and the endogenous NO generated by them failed to modify P-selectin expression in ADP-activate d platelets.