HDL-ApoA-I kinetics in response to 16 wk of exercise training in men with nonalcoholic fatty liver disease

Abstract

HDL-ApoA-I kinetics in response to 16 wk of exercise training in men with nonalcoholic fatty liver disease (NAFLD). Am J Physiol Endocrinol Metab 318: E839-E847, 2020. First published April 14, 2020; doi:10.1152/ ajpendo.00019.2020.-Nonalcoholic fatty liver disease (NAFLD) is characterized by low-circulating concentration of high-density lipoprotein cholesterol (HDL-C) and raised triacylglycerol (TAG). Exercise reduces hepatic fat content, improves insulin resistance and increases clearance of very-low-density lipoprotein-1 (VLDL1). However, the effect of exercise on TAG and HDL-C metabolism is unknown. We randomized male participants to 16 wk of supervised, moderate-intensity aerobic exercise (n 15), or conventional lifestyle advice (n 12). Apolipoprotein A-I (apoA-I) and VLDL-TAG and apolipoprotein B (apoB) kinetics were investigated using stable isotopes (1-[13C]-leucine and 1,1,2,3,3-2H5 glycerol) pre-and postintervention. Participants underwent MRI/spectroscopy to assess changes in visceral fat. Results are means SD. At baseline, there were no differences between exercise and control groups for age (52.4 7.5 vs. 52.8 10.3 yr), body mass index (BMI: 31.6 3.2 vs. 31.7 3.6 kg/m2), and waist circumference (109.3 7.5 vs. 110.0 13.6 cm). Percentage of liver fat was 23.8 (interquartile range 9.8-32.5%). Exercise reduced body weight (101.3 10.2 to 97.9 12.2 kg; P 0.001) and hepatic fat content [from 19.6%, interquartile range (IQR) 14.6-36.1% to 8.9% (4.4-17.8%); P 0.001] and increased the fraction HDL-C concentration (measured following ultracentrifugation) and apoA-I pool size with no change in the control group. However, plasma and VLDL1-TAG concentrations and HDL-ApoA-I fractional catabolic rate (FCR) and production rate (PR) did not change significantly with exercise. Both at baseline (all participants) and after exercise there was an inverse correlation between apoA-I pool size and VLDL-TAG and-ApoB pool size. The modest effect of exercise on HDL metabolism may be explained by the lack of effect on plasma and VLDL1-TAG.