The relation of plasma triglyceride, apolipoprotein B, and high-density lipoprotein cholesterol to postheparin lipoprotein lipase activity is dependent on apolipoprotein E polymorphism

Abstract

Postheparin plasma (PH)-lipoprotein lipase (LPL) activity has been reported to be a significant correlate of plasma triglyceride and high-density lipoprotein cholesterol (HDL-C) levels. However, some studies have failed to observe these associations. In this regard, apolipoprotein (apo) E polymorphism may play an important role, since the apo E2 isoform has unfavorable effects on the catabolism of triglyceride-rich lipoprotein particles. We have thus examined the relationships between PH-LPL activity and plasma lipoprotein-lipid levels within groups of men classified on the basis of apo E phenotypes, to verify whether apo E polymorphism could alter these associations. In men carrying the apo E2 isoform (n = 12), PH-LPL activity showed a strong negative correlation with plasma triglyceride ( r = −.72, P < .01), very-low-density lipoprotein (VLDL) triglyceride ([VLDL-TG] r = −.83, P < .001), and VLDL cholesterol ([VLDL-C] r = −.57, P < .05) levels and a positive correlation with plasma HDL-C ( r = .87, P < .001) and HDL 2-C ( r = .90, P < .001) concentrations. These correlations were also noted for plasma apo B levels ( r = −.65, P < .05), VLDL-apo B concentrations ( r = −.76, P < .01), and the HDL-C to cholesterol ratio ( r = .85, P < .001). In contrast, none of these associations were found in men carrying the apo E4 isoform (n = 11). In men homozygous for the apo E3 isoform (n = 29), PH-LPL activity was only significantly correlated with plasma HDL 2-C levels ( r = .46, P < .01). Results of the present study indicate that PH-LPL activity is related to plasma triglyceride, VLDL-TG, VLDL-C, VLDL-apo B, apo B, and HDL-C levels and the HDL-C to cholesterol ratio in men carrying the apo E2 isoform, but not in men homozygous for the apo E3 isoform or among apo E4 carriers. Thus, apo E polymorphism appears to modulate the effect of variation in PH-LPL activity on the plasma lipoprotein profile.