Abstract

Lipoprotein lipase (LPL) is a key rate-limiting enzyme for the hydrolysis of triacylglycerol (TAG) in chylomicrons and very low-density lipoprotein. Given that postprandial assessment of lipoprotein metabolism may provide a more physiological perspective of disturbances in lipoprotein homeostasis compared to assessment in the fasting state, we have investigated the influence of two commonly studied LPL polymorphisms (rs320, HindIII; rs328, S447X) on postprandial lipaemia, in 261 participants using a standard sequential meal challenge. S447 homozygotes had lower fasting HDL-C (p = 0.015) and a trend for higher fasting TAG (p = 0.057) concentrations relative to the 447X allele carriers. In the postprandial state, there was an association of the S447X polymorphism with postprandial TAG and glucose, where S447 homozygotes had 12% higher TAG area under the curve (AUC) (p = 0.037), 8.4% higher glucose-AUC (p = 0.006) and 22% higher glucose-incremental area under the curve (IAUC) (p = 0.042). A significant gene–gender interaction was observed for fasting TAG (p = 0.004), TAG-AUC (Pinteraction = 0.004) and TAG-IAUC (Pinteraction = 0.016), where associations were only evident in men. In conclusion, our study provides novel findings of an effect of LPL S447X polymorphism on the postprandial glucose and gender-specific impact of the polymorphism on fasting and postprandial TAG concentrations in response to sequential meal challenge in healthy participants.

Highlights

  • Large prospective cohort studies have identified elevated non-fasting triacylglycerol (TAG) concentrations as an independent risk factor for cardiovascular disease (CVD) [1]

  • The frequency of carriers of 447X in this study was consistent with published reports in Caucasian population [19]. 56% of participants were homozygous for the H1 major allele for HindIII (n = 131) with 43% H2 minor allele carriers (n = 100)

  • Values are meanstandard deviation. p-Values are from a linear model testing the association with Lipoprotein lipase (LPL)-S447X, adjusted for age, gender, body mass index (BMI); Abbreviations: TC, total cholesterol; TAG, triacylglycerol; high-density lipoprotein cholesterol (HDL-C), high density lipoprotein cholesterol; low-density lipoprotein cholesterol (LDL-C), low density lipoprotein cholesterol; Non-esterified fatty acids (NEFA), non-esterified fatty acids; homeostasis model assessment of insulin resistance (HOMA-IR), homeostasis model assessment—insulin resistance; For the baseline analysis, the insulin and HOMA-IR values were available for 166 participants; For the postprandial analysis, the insulin area under the curve (AUC) and incremental area under the curve (IAUC) data was available for 79 participants

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Summary

Introduction

Large prospective cohort studies have identified elevated non-fasting triacylglycerol (TAG) concentrations as an independent risk factor for cardiovascular disease (CVD) [1]. Endothelial associated Lipoprotein lipase (LPL) (E.C. 3.1.1.34) plays an important role in the metabolism and clearance of triacylglycerol (TAG)-rich lipoproteins from the circulation [5] and atherogenesis, where it influences the interaction between atherogenic lipoproteins and receptors on the vascular wall [6] Enzymes such as Lipoprotein lipase (LPL) (E.C. 3.1.1.34) that regulate lipoprotein metabolism in the postprandial state [7] are of interest to the prevention of CVDs. Several polymorphisms in the LPL gene have been shown to lead to a reduction in enzyme synthesis and activity and, to date, rs320 [HindIII (G/T)] and rs328 [Serine 447 Stop S447X (C/G)] have been the most extensively studied. In the present study, we investigated the association of the two commonly studied LPL polymorphisms [rs320 (HindIII) and rs328 (S447)] with fasting and postprandial lipid concentrations by using a standard sequential meal challenge and examined the penetrance of genotype according to gender, with gender previously shown to be a modulator of the impact of other variants on postprandial TAG handling [18]

Results
Discussion
Subjects
Sequential Test Meal Protocols
Biochemical Measurements
DNA Extraction and Genotyping
Statistical Analysis

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