Lifestyle intervention enhances high-density lipoprotein function among patients with metabolic syndrome only at normal low-density lipoprotein cholesterol plasma levels

Abstract

Metabolic syndrome (MetS) is associated with altered lipoprotein metabolism and impairment in the functionality of small, dense high-density lipoprotein (HDL) particles secondary to compositional alterations. The objective of this study was to investigate the capacity of a lifestyle program to improve the composition and antioxidative function (AOX) of small dense HDL3c in MetS. Patients with MetS (n=33) not taking lipid-lowering drugs were recruited to follow a 12-week educational program to reduce caloric intake and to increase physical activity. HDL subfractions were preparatively isolated by isopycnic density-gradient ultracentrifugation. AOX of HDL3c was assessed as its capacity to inhibit low-density lipoprotein oxidation induced by an azoinitiator. AOX of HDL3c was significantly improved (mean reduction in the propagation rate of low-density lipoprotein oxidation by HDL3c, -6.8%, P=.03) and systemic oxidative stress, assessed as plasma levels of 8-isoprostanes, tended to decrease in normocholesterolemic MetS patients (low-density lipoprotein cholesterol [LDL-C] < 130mg/dL) but not in patients with elevated LDL-C levels and in the whole study population. In both the whole study population and the normocholesterolemic subgroup, lifestyle intervention resulted in a significant degree of normalization of HDL3c composition, (enrichment in apolipoprotein A-I and cholesteryl esters, depletion in triglycerides), which was more pronounced at LDL-C < 130mg/dL. In patients with MetS, a lifestyle program improves AOX of small, dense HDL in subjects with normal LDL-C levels. Correction of HDL composition, involving partial normalization of apoA-I content and core lipid composition, 2 central features of the lipid hydroperoxide-inactivating capacity of HDL, may account for this effect.