Phenotypic abnormalities in macrophages from leptin-deficient, obese mice

Am J Physiol. 1999 Feb;276(2):C386-94. doi: 10.1152/ajpcell.1999.276.2.C386.

Abstract

Obesity is a complex syndrome that involves defective signaling by a number of different factors that regulate appetite and energy homeostasis. Treatment with exogenous leptin reverses hyperphagia and obesity in ob/ob mice, which have a mutation that causes leptin deficiency, proving the importance of this factor and its receptors in the obesity syndrome. Cells with leptin receptors have been identified outside of the appetite regulatory centers in the brain. Thus leptin has peripheral targets. Because macrophages express signaling-competent leptin receptors, these cells may be altered during chronic leptin deficiency. Consistent with this concept, the present study identifies several phenotypic abnormalities in macrophages from ob/ob mice, including decreased steady-state levels of uncoupling protein-2 mRNA, increased mitochondrial production of superoxide and hydrogen peroxide, constitutive activation of CCAAT enhancer binding protein (C/EBP)-beta, an oxidant-sensitive transcription factor, increased expression of interleukin-6 and cyclooxygenase (COX)-2, two C/EBP-beta target genes, and increased COX-2-dependent production of PGE2. Given the importance of macrophages in the general regulation of inflammation and immunity, these alterations in macrophage function may contribute to obesity-related pathophysiology.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • CCAAT-Enhancer-Binding Proteins
  • Cyclooxygenase 2
  • DNA-Binding Proteins / metabolism
  • Dinoprostone / biosynthesis
  • Homeostasis / physiology
  • Hydrogen Peroxide / metabolism
  • Interleukin-6 / metabolism
  • Ion Channels
  • Isoenzymes / metabolism
  • Leptin
  • Macrophages, Peritoneal / physiology*
  • Membrane Transport Proteins*
  • Mice / genetics
  • Mitochondria / metabolism
  • Mitochondrial Proteins*
  • Nuclear Proteins / metabolism
  • Obesity / genetics*
  • Obesity / metabolism*
  • Obesity / pathology
  • Phenotype
  • Prostaglandin-Endoperoxide Synthases / metabolism
  • Proteins / genetics
  • Proteins / metabolism*
  • RNA, Messenger / metabolism
  • Superoxides / metabolism
  • Uncoupling Protein 2

Substances

  • CCAAT-Enhancer-Binding Proteins
  • DNA-Binding Proteins
  • Interleukin-6
  • Ion Channels
  • Isoenzymes
  • Leptin
  • Membrane Transport Proteins
  • Mitochondrial Proteins
  • Nuclear Proteins
  • Proteins
  • RNA, Messenger
  • Ucp2 protein, mouse
  • Uncoupling Protein 2
  • Superoxides
  • Hydrogen Peroxide
  • Cyclooxygenase 2
  • Prostaglandin-Endoperoxide Synthases
  • Dinoprostone