title: Inflammation increases plasma angiopoietin-like protein 4 in patients with the metabolic syndrome and type 2 diabetes.
abstract: BACKGROUND
  Angiopoietin-like protein 4 (ANGPTL4) inhibits lipoprotein lipase and associates with dyslipidemia. The expression of ANGPTL4 is regulated by free fatty acids (FFA) that activate lipid-sensing peroxisome proliferator-activated receptors (PPARs), but FFA can also activate pattern recognition receptors including Toll-like receptor 4 (TLR4) in macrophages.
  
  
  OBJECTIVE
  To assess whether systemic low-grade inflammation is a determinant for plasma ANGPTL4 levels in patients with the metabolic syndrome (MetS) and type 2 diabetes mellitus (T2DM).
  
  
  METHODS
  We studied 335 male participants: healthy controls (Controls), patients with the MetS without inflammation (MetS-I) and with low-grade inflammation (MetS+I), and patients with T2DM. All patients without diabetes included in the present study were initially matched for waist circumference. In plasma, ANGPTL4, C reactive protein (CRP) and metabolic parameters were determined. Underlying mechanisms were examined using human macrophages in vitro.
  
  
  RESULTS
  As compared with Controls, plasma ANGPTL4 levels were increased in patients with MetS-I, MetS+I, and T2DM. Furthermore, ANGPTL4 was increased in T2DM compared with MetS-I. In fact, plasma CRP correlated positively with plasma ANGPTL4. In vitro studies showed that TLR 3/4 activation largely increased the expression and release of ANGPTL4 by macrophages.
  
  
  CONCLUSIONS
  Plasma ANGPTL4 levels in humans are predicted by CRP, a marker of inflammation, and ANGPTL4 expression by macrophages is increased by inflammatory stimuli.
authors.affiliation: Departments of Endocrinology and Metabolic Diseases , Leiden University Medical Center , Leiden , The Netherlands.
authors.forename: Nathanja
authors.initials: N
authors.lastname: Tjeerdema
authors.affiliation: Nutrition, Metabolism and Genomics group , Wageningen University , Wageningen , The Netherlands.
authors.forename: Anastasia
authors.initials: A
authors.lastname: Georgiadi
authors.affiliation: Departments of Endocrinology and Metabolic Diseases , Leiden University Medical Center , Leiden , The Netherlands.
authors.forename: Jacqueline T
authors.initials: JT
authors.lastname: Jonker
authors.affiliation: Departments of Endocrinology and Metabolic Diseases , Leiden University Medical Center , Leiden , The Netherlands.
authors.forename: Marjolijn
authors.initials: M
authors.lastname: van Glabbeek
authors.affiliation: Departments of Endocrinology and Metabolic Diseases , Leiden University Medical Center , Leiden , The Netherlands.
authors.forename: Reza
authors.initials: R
authors.lastname: Alizadeh Dehnavi
authors.affiliation: Departments of Endocrinology and Metabolic Diseases , Leiden University Medical Center , Leiden , The Netherlands.
authors.forename: Jouke T
authors.initials: JT
authors.lastname: Tamsma
authors.affiliation: Departments of Endocrinology and Metabolic Diseases , Leiden University Medical Center , Leiden , The Netherlands ; Department of Internal Medicine , University Medical Center Nijmegen , Nijmegen , The Netherlands.
authors.forename: Johannes W A
authors.initials: JW
authors.lastname: Smit
authors.affiliation: Nutrition, Metabolism and Genomics group , Wageningen University , Wageningen , The Netherlands.
authors.forename: Sander
authors.initials: S
authors.lastname: Kersten
authors.affiliation: Departments of Endocrinology and Metabolic Diseases , Leiden University Medical Center , Leiden , The Netherlands ; Department of Einthoven Laboratory for Experimental Vascular Medicine , Leiden University Medical Center , Leiden , The Netherlands.
authors.forename: Patrick C N
authors.initials: PC
authors.lastname: Rensen
keywords: Inflammatory Process in Diabetes; Metabolic Syndrome