Elevated plasma cholesteryl ester transfer in NIDDM: relationships with apolipoprotein B-containing lipoproteins and phospholipid transfer protein

Abstract

Lecithin:cholesteryl acyl transferase (LCAT) and cholesteryl ester transfer protein (CETP) are key factors in the esterification of cholesterol and the subsequent transfer of cholesteryl ester from high density lipoproteins (HDL) towards very low and low density lipoproteins (VLDL+LDL). Phospholipid transfer protein (PLTP), lipoprotein lipase (LPL) and hepatic lipase (HL) are involved in plasma phospholipid and triglyceride metabolism and also affect HDL. Equivocal changes in plasma cholesteryl ester transfer have been reported in non-insulin-dependent diabetes mellitus (NIDDM). In 16 NIDDM men with plasma triglycerides ≤4.5 mmol/l and cholesterol ≤8.0 mmol/l, plasma cholesteryl ester transfer (CET), cholesterol esterification rate, LCAT and PLTP activity levels were higher ( P<0.05 to P<0.02) in conjunction with higher plasma triglycerides ( P<0.01) and lower HDL cholesterol and cholesteryl ester levels ( P<0.05) compared to 16 matched healthy men. Multiple stepwise regression analysis demonstrated that CET was positively related to VLDL+LDL cholesterol ( P<0.001), triglycerides ( P=0.001), PLTP activity ( P=0.007) and CETP activity ( P=0.008, multiple r=0.94). NIDDM had no effect on CET, independently from these parameters. HDL cholesteryl ester was negatively related to CET ( P=0.017), HL activity ( P=0.033) and NIDDM ( P=0.047) and positively to LCAT activity levels ( P=0.034, multiple r=0.68). It is concluded that the elevated CET in plasma from NIDDM patients is associated with higher plasma triglycerides and PLTP activity levels. Furthermore, our data suggest that in normo- and moderately dyslipidaemic subjects PLTP and CETP activity levels per se may influence the rate of cholesteryl ester transfer in plasma. Plasma cholesteryl ester transfer appears to be a determinant of HDL cholesteryl ester, but other factors are likely to contribute to lower HDL cholesteryl ester levels in NIDDM.