Apolipoprotein C-III glycoforms correlate heterogeneously with plasma lipid profile in subjects with coronary artery disease

AIMS: Apolipoprotein C-III (ApoC-III) is well recognized as a main determinant of triglyceride (TG) plasma concentration and plays a crucial role in coronary artery disease (CAD). However, data on ApoC-III glycoforms are only sparse so far. The aim of this study was to quantify ApoC-III glycoforms in CAD patients and to assess their correlations with plasma lipids. METHODS: ApoC-III glycoforms were analysed by mass spectrometry in 55 subjects with clinically stable CAD (90.9% males, mean age 70.2±7.9 years) within the framework of the Verona Heart Study. RESULTS: Three different ApoC-III glycoforms were identified: non-sialylated (ApoC-III0), monosialylated (ApoC-III1), and disialylated isoforms (ApoC-III2). The analyses were performed on the relative proportion of ApoC-III glycoforms. ApoC-III0 correlated negatively with total ApoC-III concentration (R=-0.351;P=0.009), ApoC-III1 had a positive correlation (R=0.382;P=0.004), while ApoC-III2 did not have significant correlation. The different glycoforms showed different pattern of correlations with the other parameters of plasma lipid profile. ApoC-III0 was inversely correlated with TG (R=-0.421;P=0.001), total cholesterol (R=-0.314;P=0.020), LDL cholesterol (R=-0.317;P=0.018), ApoE (R=-0.434;P=0.001), and Apo B (R=-0.292;P=0.030), while ApoC-III1 was directly correlated with TG (R=0.438;P=0.001) ), total cholesterol (R=0.280;P=0.038), LDL cholesterol (R=0.337;P=0.012), ApoE (R=0.457;P=0.001), and ApoB (R=0.288;P=0.033). On the other hand, no significant correlation was found for ApoC-III2. The ApoC-III1/ApoC-III0 ratio was a significant predictor of both TG (β=0.201;P=0.025) and ApoE levels (β=0.270; P=0.016) in linear regression models adjusted for sex, age, and total ApoC-III concentration. CONCLUSIONS: ApoC-III glycoforms have heterogeneous correlations with plasma lipids in CAD patients, suggesting that they could have different metabolic properties and biological activities.