Deficiency in gp91^Phox (NOX2) Protects against Oxidative Stress and Cardiac Dysfunction in Iron Overloaded Mice

The role of NADPH oxidase subunit, gp91^phox (NOX2) in development of oxidative stress and cardiac dysfunction due to iron (Fe)-overload was assessed. Control (C57BL/6J) and gp91^phox knockout (KO) mice were treated for up to 8 weeks with Fe (2.5 mg/g/wk, i.p.) or Na-dextran; echocardiography, plasma 8-isoprostane (lipid peroxidation marker), cardiac Fe accumulation (Perl’s staining), and CD11b+ (WBCs) infiltrates were assessed. Fe caused no adverse effects on cardiac function at 3 weeks. At 6 weeks, significant declines in left ventricular (LV) ejection fraction (14.6% lower), and fractional shortening (19.6% lower) occurred in the Fe-treated control, but not in KO. Prolonging Fe treatment (8 weeks) maintained the depressed LV systolic function with a trend towards diastolic dysfunction (15.2% lower mitral valve E/A ratio) in controls but produced no impact on the KO. Fe-treatment (8 weeks) caused comparable cardiac Fe accumulation in both strains, but a 3.3-fold elevated plasma 8-isoprostane, and heightened CD11b+ staining in controls. In KO mice, lipid peroxidation and CD11b+ infiltration were 50% and 68% lower, respectively. Thus, gp91^phox KO mice were significantly protected against oxidative stress, and systolic and diastolic dysfunction, supporting an important role of NOX2-mediated oxidative stress in causing cardiac dysfunction during Fe overload. View Full-Text