Abstract 5325: Inherited Human Nox2 Deficiency is Associated With Impaired Isoprostane Formation and Reduced Platelet Recruitment

Abstract

Platelet isoprostane PGF2 α -III, a pro-aggregating molecule, is believed to derive from non enzymatic oxidation of arachidonic acid. We assessed the hypothesis that PGF2 α -III derives also from gp91phox activation and contributes to the phenomenon of platelet recruitment. We studied PGF2 α -III in platelets from 8 male patients with hereditary deficiency of gp91phox (Nox2) the catalytic subunit of NADPH oxidase, and 8 male controls. Gp91phox deficency is a very rare human disease(prevalence 1:1000.000) characterized by life-threatening infections. Patients were a subgroup from a multicentre study in collaboration with the Italian Primary Immunodeficiency Network (IPINET). Upon stimulation platelets from healthy subjects produced PGF2 α -III, that was inhibited 8% by aspirin and 43% by an inhibitor of gp91phox. Also, in platelets incubated with a gp91phox inhibitor or with SQ29548, a thromboxane A2 receptors inhibitor, platelet recruitment, an in vitro model of thrombus growth, was reduced by 52% and 84% respectively; a lower effect (−13%) was seen with aspirin. Incubation of normal platelets with PGF2 α -III dose-dependently(1–100 pM) increased platelet recruitment by mobilizing platelet Ca2+ and activating gpIIb/IIIa. Platelets from patients with gp91phox hereditary deficiency had normal thromboxane A2 formation and 75% PGF2 α -III reduction compared to controls. In gp91phox-deficient patients agonist-induced platelet aggregation was within the normal range while platelet recruitment was reduced compared to controls. Incubation of gp91phox-deficient platelets with PGF2 α -III (1–100 pM) partially restored platelet recruitment. In conclusion this study provides the first evidence that platelet PGF2 α -III maximally derives from Nox2 activation and contributes to platelet recruitment via activation of gpIIb/IIIa.