Induction of heme oxygenase-1 with hemin reduces obesity-induced adipose tissue inflammation via adipose macrophage phenotype switching

Mediators Inflamm. 2014:2014:290708. doi: 10.1155/2014/290708. Epub 2014 Nov 11.

Abstract

Adipose macrophages with the anti-inflammatory M2 phenotype protect against obesity-induced inflammation and insulin resistance. Heme oxygenase-1 (HO-1), which elicits antioxidant and anti-inflammatory activity, modulates macrophage phenotypes and thus is implicated in various inflammatory diseases. Here, we demonstrate that the HO-1 inducer, hemin, protects against obesity-induced adipose inflammation by inducing macrophages to switch to the M2 phenotype. HO-1 induction by hemin reduced the production of proinflammatory cytokines (TNF-α and IL-6) from cocultured adipocytes and macrophages by inhibiting the activation of inflammatory signaling molecules (JNK and NF-κB) in both cell types. Hemin enhanced transcript levels of M2 macrophage marker genes (IL-4, Mrc1, and Clec10a) in the cocultures, while reducing transcripts of M1 macrophage markers (CD274 and TNF-α). The protective effects of hemin on adipose inflammation and macrophage phenotype switching were confirmed in mice fed a high-fat diet, and these were associated with PPARγ upregulation and STAT6 activation. These findings suggest that induction of HO-1 with hemin protects against obesity-induced adipose inflammation through M2 macrophage phenotype switching, which is induced by the PPARγ and STAT6 pathway. HO-1 inducers such as hemin may be useful for preventing obesity-induced adipose inflammation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3-L1 Cells
  • Adipocytes / drug effects
  • Adipocytes / metabolism
  • Adipocytes / pathology
  • Adipose Tissue / drug effects*
  • Adipose Tissue / metabolism
  • Adipose Tissue / pathology
  • Animals
  • Cell Line
  • Coculture Techniques
  • Cytokines / metabolism
  • Enzyme Induction / drug effects
  • Heme Oxygenase-1 / biosynthesis*
  • Hemin / pharmacology*
  • Inflammation / metabolism
  • Inflammation / pathology
  • Inflammation / prevention & control*
  • Inflammation Mediators / metabolism
  • Macrophages / drug effects*
  • Macrophages / metabolism
  • Macrophages / pathology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Obesity / drug therapy*
  • Obesity / metabolism
  • Obesity / pathology
  • Phenotype
  • Signal Transduction / drug effects

Substances

  • Cytokines
  • Inflammation Mediators
  • Hemin
  • Heme Oxygenase-1