OBESITY AND METABOLIC SYNDROME: PLASMA LIPOPROTEINS ALTERATIONS

Obesity, especially if associated with metabolic syndrome, promotes oxidative stress, a low grade chronic inflammatory state, and modify the composition and function of plasma lipoproteins. Oxidative damage to lipoproteins not only make LDL atherogenic but can also alter HDL reducing their anti-atherogenic properties. The possibility of monitoring the lipid peroxidation of the individual regions of LDL and HDL could lead to more detailed information on the molecular mechanisms that are the basis of the increased risk of cardiovascular diseases observed in obesity and metabolic syndrome. The object of this study was to investigate the susceptibility to peroxidation of plasma and of the hydrophobic core and the surrounding envelope of LDL and HDL in obese male (BMI between 25 and 35 Kg mq) with (SM, n=20)) or without (OB, n =40) metabolic syndrome. The susceptibility of plasma to peroxidation was higher in SM and OB than in normo-weight controls (CT, n=60), but not significant differences were observed between these two obese groups. Also the susceptibility to peroxidation of isolated LDL and HDL was higher in both obese groups than in CT. LDL and HDL in SM presented an higher content of triacylglicerols than the corresponding HDL of OB. Moreover, the hydrophobic core of HDL showed a risk of peroxidation significantly higher in SM than in OB. This last parameter was inversely correlated with the waist to hip ratio, an index of visceral obesity. This last evidence seems to indicate that the increase of inflammation typical of the visceral adipose tissue could be one of the major causes of the higher susceptibility to peroxidation found in the hydrophobic core of HDL. The evaluation of the susceptibility to peroxidation of the core and the envelope of LDL and HDL might contribute to the identification of a subset of patients at increased risk of metabolic and cardiovascular complications. Future “ad hoc” randomized clinical trials should be designed to address the effects of weight reduction and /or different diet and/or nutritional supplementation on these parameters.