Low serum ferroxidase I activity is associated with mortality in heart failure and related to both peroxynitrite-induced cysteine oxidation and tyrosine nitration of ceruloplasmin.

Ceruloplasmin antioxidant function is mainly related to its ferroxidase I (FeOxI) activity, which influences iron-dependent oxidative and nitrosative radical species generation. Peroxynitrite, whose production is increased in heart failure (HF), can affect ceruloplasmin antioxidant function through amino acid modification. We investigated the relationship between FeOxI and ceruloplasmin tyrosine and cysteine modification and explored in a cohort of patients with HF the potential clinical relevance of serum FeOxI. In patients with chronic HF (n=96, 76 ± 9 years; New York Heart Association class, 2.9 ± 0.8) and age-matched controls (n=35), serum FeOxI, FeOxII, ceruloplasmin, nitrotyrosine-bound ceruloplasmin, B-type natriuretic peptide, norepinephrine, and high-sensitivity C-reactive protein were measured, and the patients were followed up for 24 months. Ceruloplasmin, B-type natriuretic peptide, norepinephrine, and high-sensitivity C-reactive protein were increased in HF versus controls. FeOxI was decreased in HF (-20%) and inversely related to nitrotyrosine-bound ceruloplasmin (r, -0.305; P=0.003). In HF, FeOxI lower tertile had a mortality rate doubled compared with middle-higher tertiles. FeOxI emerged as a mortality predictor (hazard ratio, 2.95; 95% confidence intervals [1.29-6.75]; P=0.011) after adjustment for age, sex, hypertension, smoking, sodium level, estimated glomerular filtration rate, and high-sensitivity C-reactive protein. In experimental settings, peroxynitrite incubation of serum samples and isolated purified ceruloplasmin reduced FeOxI activity while increasing ceruloplasmin tyrosine nitration and cysteine thiol oxidation. Reduced glutathione prevented peroxynitrite-induced FeOxI drop, tyrosine nitration, and cysteine oxidation; flavonoid(-)-epicatechin, which prevented ceruloplasmin tyrosine nitration but not cysteine oxidation, partially impeded peroxynitrite-induced FeOxI drop. Reduced activity of serum FeOxI is associated with ceruloplasmin nitration and reduced survival in patients with HF. Both ceruloplasmin tyrosine nitration and cysteine thiol oxidation may be operant in vivo in peroxynitrite-induced FeOxI activity inhibition.