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

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 HDLbound 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[16.7e44.6]; SAP, 19.3[15.7e29.1]; control, 15.9[14.7e18.7] ng/mL; P < 0.0001). Serum PON-1 concentrations in UAP and SAP patients were significantly lower than those in control subjects (UAP, 55.6[45.9e69.7]; SAP, 55.0[46.9e64.9]; control, 62.5[51.1e78.8] mg/mL; P 0.0002). Plasma MPO levels showed a weak inverse correlation with serum PON-1 concentrations in all subjects (R=- 0.163, P < 0.0005). Moreover, in women, plasma MPO levels showed a significant inverse correlation with serum PON-1 concentrations and PON-arylesterase activity in SAP (concentration: R-0.537, P < 0.0001; arylesterase-activity: R=- 0.469, P < 0.001) and UAP (concentration: R=- 0.340, P < 0.05; arylesterase-activity: R=- 0.350, P < 0.05) patients, but not in men. 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. (C) 2013 Elsevier Ireland Ltd. All rights reserved.