Increased lipolysis by secretory phospholipase A2 group V of lipoproteins in diabetic dyslipidaemia

Abstract

Background. Lipolysis of lipoproteins by secretory phospholipase A 2 group V (sPLA2-V) promotes inflammation, lipoprotein aggregation and foam cell formation - all considered as atherogenic mechanisms. Objective. In this study, we compared the susceptibility to sPLA2-V lipolysis of VLDL and LDL from individuals with type 2 diabetes and the metabolic syndrome (T2D-MetS) and from healthy controls. Design. VLDL and LDL were isolated from 38 T2D-MetS subjects and 38 controls, treated pair-wise. Extent of sPLA2-V lipolysis was measured as release of nonesterified free fatty acids (NEFA). In a subset of the subjects, lipoprotein composition was determined as a relationship between lipid and apolipoprotein components. Results. Mean paired increase in sPLA2-V lipolysis after 1 h for T2D-MetS versus control was 2.0 μmol NEFA l-1 for VLDL (P = 0.004) and 0.75 μmol NEFA l-1 for LDL (P = 0.001). There were also substantial differences in lipoprotein composition between the groups. T2D-MetS VLDL had higher triglyceride and cholesterol contents than control VLDL. T2D-MetS LDL was smaller and contained more triglycerides and less cholesterol than control LDL. Both VLDL and LDL from T2D-MetS subjects also contained more apolipoprotein CIII per particle. Conclusion. VLDL and LDL from T2D-MetS individuals were more susceptible to sPLA2-V lipolysis than those from control individuals. This may result in elevated levels of NEFA and lysophosphatidylcholine, both in circulation and in LDL, possibly contributing to the elevated inflammatory state and increased risk of cardiovascular diseases seen in these individuals. © 2008 Blackwell Publishing Ltd.