Oxidized LDL and C-reactive protein level in relation to carotid intima-media thickness in population with risk factors for atherosclerosis

INTRODUCTION: Elevated levels of oxidized LDL cholesterol (OxLDL) are considered to be a key factor of initiating and accelerating atherosclerosis. It promotes atherosclerosis through inflammatory and immunologic mechanisms that lead to the formation of macrophage foam cells.

OBJECTIVE: To determine the relationship among OxLDL, C-reactive protein (CRP) level and carotid intima-media thickness (IMT) in population with risk factors for atherosclerosis.

METHODS: The study group consisted of 125 clinically healthy, hypercholesterolaemic subjects (49.3 +/- 5.7 years; 75 females and 50 males) compared with 100 age-matched population-based control subjects. The study group was divided into two subgroups: subgroup A (the levels of LDL cholesterol > 5 mmol/L) and subgroup B (the levels of LDL cholesterol < 5 mmol/L). None of the subjects had history of cerebrovascular, ischaemic heart disease, hypertension or diabetes mellitus. Lipid profiles were measured by enzymatic methods. OxLDL was measured by using a specific monoclonal antibody, mAb4E6. CRP was measured using hemiluminescent methods (Immulite-DPC). The common carotid IMT was measured by the B-mode ultrasound.

RESULTS: Compared to controls, the study group had higher levels of OxLDL (119.97 +/- 43.15 vs. 82.03 +/- 25.99 IU/L; p < 0.01) and CRP (6.20 +/- 3.55 vs. 2.68 +/- 3.04 mg/ml; p < 0.05). IMT was significantly higher in study subjects (1.14 +/- 0.38 vs. 0.72 +/- 0.24 mm; p < 0.05). We also found that, in the whole study group, IMT significantly positively correlated with OxLDL (r = 0.442; p < 0.05). We found that in the study subgroup A, IMT positively correlated with CRP (r = 0.792; p < 0.01). In controls, we found a significantly positive association between IMT and OxLDL (r = 0.781; p < 0.01) and CRP (r = 0.748; p < 0.01).

CONCLUSION: The elevated levels of OxLDL and CRP are associated with higher common carotid intima-media thickness in population with risk factors for atherosclerosis.