Myeloperoxidase and Paraoxonase Activity in Acute Coronary Syndrome Patients

Background: Myeloperoxidase (MPO), an oxidative stress related enzyme is elevated in Coronary Artery Disease (CAD) and is involved in development of atherosclerotic plaque. Paraoxonase (PON) an enzyme protein associated with HDL serves as an antioxidant and plays an important role in preventing the formation of Oxidized LDL (OxLDL). This suggests a conflicting role of MPO and PON in development of cardiovascular disease and atherosclerosis.

Aim: Present study was done to evaluate and compare MPO/PON ratio in Acute Coronary Syndrome (ACS) patients with controls. The study evaluates and compares the pro oxidant and pro inflammatory enzyme, MPO and anti-oxidant and anti-inflammatory enzyme, PON in ACS patients with controls. Oxidative marker, Malondialdehyde (MDA) and anti-oxidant marker, Reduced Glutathione (GSH) was assessed in ACS patients and compared with controls. An attempt was also made to correlate MPO/PON ratio to markers of oxidative stress (MDA and GSH).

Methods: Cross-sectional study carried out in Dr. Somervell Memorial CSI Medical College, Trivandrum, Kerala, India.50 ACS patients from Cardiac Care Unit and 50 age and sex matched controls without CAD from Medical College Health Checkup was selected.

Results: MPO and MPO/PON ratio were significantly high and PON was significantly lower in ACS patients compared to controls. Total cholesterol, Triglyceride, LDL, MDA were significantly high in ACS patients. Statistically significant positive correlation was observed between MPO/PON and MDA. Significant negative correlation was observed between MPO/PON and GSH.

Conclusion: Myeloperoxidase and MPO/PON ratio was significantly high in ACS patients than controls. This is suggestive of the role of MPO in oxidative damage to lipoproteins in CAD patients. Prooxidant, Paraoxonase ,and antioxidant, GSH is lowered in ACS patients as a result of the increased oxidative stress. This study suggests that MPO/PON1 ratio can be used as a predictive marker of ACS.