title: Caloric restriction and exercise increase plasma ANGPTL4 levels in humans via elevated free fatty acids.
abstract: OBJECTIVE
  Plasma lipoprotein levels are determined by the balance between lipoprotein production and clearance. Recently, angiopoietin-like protein 4 (ANGPTL4) was uncovered as a novel endocrine factor that potently raises plasma triglyceride levels by inhibiting triglyceride clearance. However, very little is known about ANGPTL4 in human. Here we set out to identify physiological determinants of plasma ANGPTL4 levels in humans, focusing on the effect of energy restriction and plasma FFAs.
  
  
  RESULTS
  We developed an ELISA for quantitative measurement of ANGPTL4 in human plasma. Using this assay we found major variations in baseline plasma ANGPTL4 levels between individuals. Within an individual, plasma ANGPTL4 levels remain stable throughout the day but increase significantly in response to long-term fasting, chronic caloric restriction, and endurance exercise. Intralipid injection as well as treatment with a beta-adrenergic agonist, both of which lead to elevated plasma FFA levels, increased plasma ANGPTL4 levels compared to control treatment. Fatty acids markedly induced ANGPTL4 gene expression in rat hepatoma FAO cells, human primary myocytes, and mouse intestinal MSIE cells.
  
  
  CONCLUSIONS
  In conclusion, our results show that plasma ANGPTL4 levels are increased by fasting, caloric restriction, and exercise, which is likely mediated by elevated plasma FFAs.
authors.affiliation: Nutrigenomics Consortium, TI Food and Nutrition, Wageningen, The Netherlands. sander.kersten@wur.nl
authors.forename: Sander
authors.initials: S
authors.lastname: Kersten
authors.forename: Laeticia
authors.initials: L
authors.lastname: Lichtenstein
authors.forename: Emma
authors.initials: E
authors.lastname: Steenbergen
authors.forename: Karin
authors.initials: K
authors.lastname: Mudde
authors.forename: Henk F J
authors.initials: HF
authors.lastname: Hendriks
authors.forename: Matthijs K
authors.initials: MK
authors.lastname: Hesselink
authors.forename: Patrick
authors.initials: P
authors.lastname: Schrauwen
authors.forename: Michael
authors.initials: M
authors.lastname: Müller