Gender-specific correlation between plasma myeloperoxidase levels and serum high-density lipoprotein-associated paraoxonase-1 levels in patients with stable and unstable coronary artery disease

Abstract Objective Low high-density lipoprotein (HDL) cholesterol is well-established as a negative risk factor for coronary artery disease (CAD) and its anti-oxidant property has been attributed mainly to the HDL-bound enzyme paraoxonase-1 (PON-1). Recently, myeloperoxidase (MPO), a pro-oxidant enzyme released from activated neutrophils, has been shown to alter the atheroprotective function of HDL to a dysfunctional form. This study investigated the relationship between plasma MPO and serum PON-1 levels in patients with stable (SAP) and unstable angina pectoris (UAP). Methods Plasma MPO levels and serum PON-1 concentration/activity were measured in patients with SAP ( n  = 226), UAP ( n  = 151) and in control subjects ( n  = 99). Results Plasma MPO levels in UAP patients were significantly higher than those in SAP patients or in control subjects (UAP, 21.6[16.7–44.6]; SAP, 19.3[15.7–29.1]; control, 15.9[14.7–18.7] ng/mL; P P  = 0.0002). Plasma MPO levels showed a weak inverse correlation with serum PON-1 concentrations in all subjects ( R  = −0.163, P R  = −0.537, P R  = −0.469, P R  = −0.340, P R  = −0.350, P Conclusion This study demonstrates that plasma MPO levels have a significant inverse correlation with PON-1 levels, especially in women, in SAP and UAP patients, and suggests that an imbalance between pro-oxidants and anti-oxidants may contribute to the progression of coronary plaque instability.