Paraoxonase-1 enzyme activity in rheumatoid arthritis patients: association with carotid intima-media thickness?

Abstract

Objectives The aim was to find the relationship of biochemical determinants of paraoxonase-1 (PON1) enzyme activity with carotid intima-media thickness (IMT) as a surrogate marker of atherosclerotic cardiovascular (CV) disease risk in patients with rheumatoid arthritis (RA). Background There is strong correlation between patients with RA and CV morbidity and mortality that cannot be explained by traditional risk factors alone. And this could be due to abnormal function of high-density lipoproteins (HDL). HDL promotes cholesterol efflux, as well as protects low-density lipoprotein (LDL) against oxidation, and this ability has been referred to as an 'anti-inflammatory' function because the lipid oxidation products derived from LDL are highly proinflammatory. PON1 is an HDL-associated enzyme that promotes antioxidant and anti-inflammatory properties of HDL by preventing the formation of oxidized LDL and inactivating oxidized phospholipids. Patients and methods The authors conducted a case–control study, including 30 RA patients and 20 controls, enrolled in Menoufia, Egypt. B-mode Doppler ultrasound imaging to measure carotid IMT, C-reactive protein (CRP), erythrocyte sedimentation rate, lipid profile, and PON1 activity were measured. Results RA patients tended to be more dyslipidemic as evidenced by decreased HDL and increased total cholesterol, tryglycerides (TGD), and LDL, which showed increased carotid IMT and decreased PON1 activity than the control group. Patients with carotid plaque tended to be more dyslipidemic and plasma PON1 activity tended to be lower than in patients without carotid plaque. A significant correlation between plasma PON1 activity and systemic inflammation as measured by the erythrocyte sedimentation rate and hsCRP level was noted. Conclusion Our data suggest that the lower the activity of PON1, the higher the atherosclerotic CV disease risk in RA patients, as assessed by the presence of carotid plaque. There is a significant correlation between plasma PON1 activity and systemic inflammation in RA patients. Higher hsCRP levels were associated with lower PON1 activity.