Multiple abnormalities in the transfer of phospholipids from VLDL and LDL to HDL in non-insulin-dependent diabetes

Transfers or exchanges of cholesterol esters and triglycerides between lipoproteins are mediated by a specialized protein referred to as cholesteryl ester transfer protein (CETP), whereas those of phospholipids (PLs) are facilitated by both CETP and a specific phospholipid transfer protein (PLTP). In the present study, the authors compared phospholipid transfer (PLT) in normal subjects and in patients with noninsulin-dependent diabetes (NIDD), which is associated with an increased risk of atherosclerosis. PLT was measured in different recombination experiments using an isotopic assay in which the transfer of labelled PLs from very low-density lipoprotein (VLDLs) and low-density lipoproteins (LDLs) to high-density lipoproteins (HDLs) was determined. This allowed discrimination between the roles of VLDLs+LDLs, HDLs, and plasma PLT activity (PLTA). VLDL+LDL-dependent PLT, HDL-dependent PLT and PLTA were decreased in NIDD. VLDL+LDL-dependent PLT was found to be negatively correlated with the PL/apolipoprotein B ratio, whereas HDL-dependent PLT was positively correlated with the HDL(2)/HDL(3) and PL/apolipoprotein A-I ratios and negatively correlated with the flow activation energy at the HDL surface. The HDL(2)/HDL(3) ratio was positively correlated with PLTA but not with CETP, which confirms previous reports suggesting that PLTP might act as an HDL conversion factor. These data show that several abnormalities in PLT occur in NIDD and raise the question as to whether a lowered PLT might be a new characteristic of dis factors associated with an increased risk of atherosclerosis.