Influence of Lipoprotein (a) on Inflammatory Biomarkers in Metabolic Syndrome

Abstract

To examine the relation between plasma lipoprotein (a) (Lp[a]) levels and oxidative stress biomarkers, serum cytokines, and atherosclerotic burden among individuals recently diagnosed as having metabolic syndrome (MS). Eighty-four white patients with MS were classified according to two Lp(a) levels (normal Lp[a]: < 30 mg/dL or high Lp[a]: > 30 mg/dL) and were compared with 42 healthy controls. Oxidative stress biomarkers (oxidized low-density lipoprotein, antibodies to oxidized low-density lipoprotein, and nitric oxide metabolites) and proinflammatory cytokines (interleukin [IL]-2, IL-4, IL-5, IL-6, IL-10, IL-12P70, IL-13, and interferon-γ) were measured in plasma. Atherosclerotic significance was determined using carotid ultrasound and endothelial function by standardized protocols. Patients with MS had higher levels of serum cytokines, oxidative stress markers, and C-reactive protein, and greater atherosclerosis burden as compared with controls. Among the group members, 58 patients had normal Lp(a) levels and 26 had high Lp(a) levels. Cytokines and C-reactive protein levels were significantly higher in patients with high Lp(a) compared with those with normal Lp(a) (P < 0.01 for IL-2 and P < 0.001 for the others). Nitric oxide metabolites were significantly lower in patients with high Lp(a) as compared with those with normal Lp(a) (P < 0.05). No differences were found in oxidized low-density lipoprotein and atherosclerotic burden between the two groups of patients with MS with respect to Lp(a) levels. Elevated Lp(a) plasma levels are associated with higher proinflammatory markers in patients newly diagnosed as having MS.