Myeloid heme oxygenase-1 haploinsufficiency reduces high fat diet-induced insulin resistance by affecting adipose macrophage infiltration in mice

PLoS One. 2012;7(6):e38626. doi: 10.1371/journal.pone.0038626. Epub 2012 Jun 21.

Abstract

Increased adipose tissue macrophages contribute to obesity-induced metabolic syndrome. Heme oxygenase-1 (HO-1) is a stress-inducible enzyme with potent anti-inflammatory and proangiogenic activities in macrophages. However, the role of macrophage HO-1 on obesity-induced adipose inflammation and metabolic syndrome remains unclear. Here we show that high-fat diet (HFD) feeding in C57BL/6J mice induced HO-1 expression in the visceral adipose tissue, particularly the stromal vascular fraction. When the irradiated C57BL/6J mice reconstituted with wild-type or HO-1(+/-) bone marrow were fed with HFD for over 24 weeks, the HO-1(+/-) chimeras were protected from HFD-induced insulin resistance and this was associated with reduced adipose macrophage infiltration and angiogenesis, suggesting that HO-1 affects myeloid cell migration toward adipose tissue during obesity. In vivo and in vitro migration assays revealed that HO-1(+/-) macrophages exhibited an impaired migration response. Chemoattractant-induced phosphorylation of p38 and focal adhesion kinase (FAK) declined faster in HO-1(+/-) macrophages. Further experiments demonstrated that carbon monoxide and bilirubin, the byproducts derived from heme degradation by HO-1, enhanced macrophage migration by increasing phosphorylation of p38 and FAK, respectively. These data disclose a novel role of hematopoietic cell HO-1 in promoting adipose macrophage infiltration and the development of insulin resistance during obesity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipose Tissue / cytology
  • Adipose Tissue / metabolism
  • Adiposity*
  • Animals
  • Bilirubin / pharmacology
  • Blotting, Western
  • Carbon Monoxide / pharmacology
  • Cell Movement*
  • Diet, High-Fat / adverse effects*
  • Enzyme-Linked Immunosorbent Assay
  • Fatty Liver / etiology
  • Fatty Liver / metabolism
  • Fatty Liver / pathology
  • Female
  • Focal Adhesion Kinase 1 / genetics
  • Focal Adhesion Kinase 1 / metabolism
  • Haploinsufficiency*
  • Heme Oxygenase-1 / physiology*
  • Immunoenzyme Techniques
  • Inflammation / etiology
  • Inflammation / metabolism
  • Inflammation / pathology
  • Inflammation Mediators / metabolism
  • Insulin / pharmacology
  • Insulin Resistance*
  • Macrophages, Peritoneal / metabolism
  • Macrophages, Peritoneal / pathology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Myeloid Cells / enzymology*
  • Myeloid Cells / pathology
  • Obesity / etiology
  • Obesity / metabolism
  • Obesity / pathology
  • Phosphorylation
  • RNA, Messenger / genetics
  • Reactive Oxygen Species / metabolism
  • Real-Time Polymerase Chain Reaction
  • Reverse Transcriptase Polymerase Chain Reaction
  • p38 Mitogen-Activated Protein Kinases / genetics
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • Inflammation Mediators
  • Insulin
  • RNA, Messenger
  • Reactive Oxygen Species
  • Carbon Monoxide
  • Heme Oxygenase-1
  • Focal Adhesion Kinase 1
  • Ptk2 protein, mouse
  • p38 Mitogen-Activated Protein Kinases
  • Bilirubin