Changes in low-density lipoprotein size phenotypes associate with changes in apolipoprotein C-III glycoforms after dietary interventions

Abstract

The presence of small dense low-density lipoprotein (LDL) is associated with obesity, type II diabetes, and an increased risk for cardiovascular disease. Apolipoprotein C-III (apoC-III) is involved in the formation of small dense LDL, but the exact mechanisms are still not well defined. ApoC-III is a glycosylated apolipoprotein, with 3 major glycoforms: apoC-III0, apoC-III1, and apoC-III2 that contain 0, 1, or 2 molecules of sialic acid, respectively. In our previous work, we reported an association among apoC-III0 and apoC-III1, but not apoC-III2 with fasting plasma triglyceride levels in obesity and type II diabetes. The goal of this study was to determine the relationship between changes in the major apoC-III glycoforms and small dense LDL levels after dietary interventions. Mass spectrometric immunoassay was performed on fasting plasma samples from 61 subjects who underwent either a high-carbohydrate diet (n=34) or a weight loss intervention (n=27). After both dietary interventions, changes in total apoC-III concentrations were associatedwith changes in LDL peak particle diameter (r=-0.58, P<.0001). Increases in total apoC-III concentrations after the high-carbohydrate diet were associated with decreases in LDL size (r=-0.53, P=.001), and decreases in apoC-III concentrations after weight loss were associated with increases in LDL peak particle diameter (r=-0.54, P=.004). Changes in concentrations of apoC-III1 and apoC-III0, but not apoC-III2, were associated with changes in LDL peak particle diameter in both the weight loss and high-carbohydrate interventions. We conclude that apoC-III0 and apoC-III1, but not apoC-III2 are associated with the formation of small dense LDL.