Associations between Endothelial Lipase and Apolipoprotein B-Containing Lipoproteins Differ in Healthy Volunteers and Metabolic Syndrome Patients

Abstract

The association between serum levels of endothelial lipase (EL) and the serum levels and composition of apolipoprotein B (apoB)-containing lipoproteins in healthy subjects and patients with metabolic syndrome (MS) remained unexplored. Therefore, in the present study, we determined the serum levels and lipid content of apoB-containing lipoproteins using nuclear magnetic resonance (NMR) spectroscopy and examined their association with EL serum levels in healthy volunteers (HVs) and MS patients. EL was significantly negatively correlated with the serum levels of cholesterol in large very low-density lipoprotein (VLDL) particles, as well as with total-cholesterol-, free-cholesterol-, triglyceride-, and phospholipid-contents of VLDL and intermediate-density lipoprotein particles in MS patients but not in HVs. In contrast, EL serum levels were significantly positively correlated with the serum levels of apoB, triglycerides, and phospholipids in large low-density lipoprotein particles in HVs but not in MS patients. EL serum levels as well as the serum levels and lipid content of the majority of apoB-containing lipoprotein subclasses were markedly different in MS patients compared with HVs. We conclude that EL serum levels are associated with the serum levels and lipid content of apoB-containing lipoproteins and that these associations are markedly affected by MS.

Keywords: NMR spectroscopy; apolipoprotein B-containing lipoproteins; endothelial lipase; lipoprotein subclasses; metabolic syndrome.

Figure 1

Correlations of EL with (A) VLDL-C/VLDL-apoB, (B) VLDL-FC/VLDL-apoB, (C) VLDL-TG/VLDL-apoB, and (D) VLDL-PL/VLDL-apoB in HVs and MS patients. VLDL parameters used for the calculations of the ratios were in mg/dL. Correlations were quantified using Spearman’s correlation coefficient. p-values < 0.05 are considered statistically significant. C, cholesterol; FC, free cholesterol; HV, healthy volunteer; mL, milliliter; MS, metabolic syndrome patient; r, Spearman’s correlation coefficient; TG, triglyceride; pg, picogram; PL, phospholipid; VLDL, very low-density lipoprotein.

Figure 2

Correlations of EL with (A) IDL-C/IDL-apoB, (B) IDL-FC/IDL-apoB, (C) IDL-TG/IDL-apoB, and (D) IDL-PL/IDL-apoB in HVs and MS patients. IDL parameters used for the calculations of the ratios were in mg/dL. Correlations were quantified using Spearman’s correlation coefficient. p-values < 0.05 are considered statistically significant. C, cholesterol; FC, free cholesterol; HV, healthy volunteer; IDL, intermediate-density lipoprotein; mL, milliliter; MS, metabolic syndrome patient; r, Spearman’s correlation coefficient; TG, triglyceride; pg, picogram; PL, phospholipid.