Marcella E O'Reilly1,2, Yvonne M Lenighan1,2, Eugene Dillon3,2, Sarina Kajani4,2,5, Sean Curley4,2,5, Robyn Bruen4,2, Rachel Byrne4,2,5, Aoibhin Moore Heslin1,2, Aidan P Moloney6, Helen M Roche1,7,2, Fiona C McGillicuddy4,2,5. 1. Nutrigenomics Research Group, School of Public Health Physiotherapy and Sports Science, University College Dublin, Dublin 4, Ireland. 2. UCD Conway Institute, University College Dublin, Dublin 4, Ireland. 3. Mass Spectrometry Resource, University College Dublin, Dublin 4, Ireland. 4. Diabetes Complications Research Centre, University College Dublin, Dublin 4, Ireland. 5. UCD School of Medicine, University College Dublin, Dublin 4, Ireland. 6. Teagasc, Animal & Grassland Research and Innovation Centre, Meath, Ireland. 7. UCD Institute of Food and Health, University College Dublin, Dublin 4, Ireland.
Abstract
SCOPE: High-fat diet (HFD)-induced obesity impairs macrophage-to-feces reverse cholesterol transport (RCT). It is hypothesized that dietary supplementation with the polyunsaturated fatty acids conjugated linoleic acid (CLA) or alpha linolenic acid (ALA) would prevent HFD-impaired RCT by modulating hepatic protein pathways. METHODS AND RESULTS: ApoE3L.CETP mice are fed a HFD supplemented ± CLA or ALA for 12 weeks and in vivo macrophage-to-feces RCT is determined. Hepatic cholesterol transporters and the hepatic proteome are assessed by immunoblotting and mass spectrometry, respectively. Mice fed HFD alone, but not ALA-HFD or CLA-HFD, exhibit increased systemic cholesterol levels, increased 3 H-cholesterol levels in plasma and liver but not feces during RCT, and reduced hepatic ABCG5/8 expression relative to LFD. ALA-HFD significantly reduces liver weight, hepatic cholesterol levels, and expression of the cholesterol synthesis enzyme farnesyl pyrophosphate synthase relative to HFD. ALA further increases the expression of acetyl-coA oxidase-associated proteins and suppress PPARα-induced proteins relative to HFD. CLA does not significantly attenuate hepatic lipid levels but is associated with reduced hepatic expression of fatty acid binding protein (FABP)-1/FABP4 levels relative to HFD, and reduced inflammatory pathway activation relative to ALA-HFD. CONCLUSION: ALA and CLA exert distinct mechanistic advantages on cholesterol homeostasis and RCT in obesity.
SCOPE: High-fat diet (HFD)-induced obesity impairs macrophage-to-feces reverse cholesterol transport (RCT). It is hypothesized that dietary supplementation with the polyunsaturated fatty acids conjugated linoleic acid (CLA) or alpha linolenic acid (ALA) would prevent HFD-impaired RCT by modulating hepatic protein pathways. METHODS AND RESULTS: ApoE3L.CETP mice are fed a HFD supplemented ± CLA or ALA for 12 weeks and in vivo macrophage-to-feces RCT is determined. Hepatic cholesterol transporters and the hepatic proteome are assessed by immunoblotting and mass spectrometry, respectively. Mice fed HFD alone, but not ALA-HFD or CLA-HFD, exhibit increased systemic cholesterol levels, increased 3 H-cholesterol levels in plasma and liver but not feces during RCT, and reduced hepatic ABCG5/8 expression relative to LFD. ALA-HFD significantly reduces liver weight, hepatic cholesterol levels, and expression of the cholesterol synthesis enzyme farnesyl pyrophosphate synthase relative to HFD. ALA further increases the expression of acetyl-coA oxidase-associated proteins and suppress PPARα-induced proteins relative to HFD. CLA does not significantly attenuate hepatic lipid levels but is associated with reduced hepatic expression of fatty acid binding protein (FABP)-1/FABP4 levels relative to HFD, and reduced inflammatory pathway activation relative to ALA-HFD. CONCLUSION:ALA and CLA exert distinct mechanistic advantages on cholesterol homeostasis and RCT in obesity.