Autoamplification of tumor necrosis factor-alpha: a potential mechanism for the maintenance of elevated tumor necrosis factor-alpha in male but not female obese mice

Am J Pathol. 2006 Feb;168(2):435-44. doi: 10.2353/ajpath.2006.050699.


Although tumor necrosis factor-alpha (TNF-alpha) is elevated in adipose tissue in obesity and may contribute to the cardiovascular and metabolic risks associated with this condition, the mechanisms leading to elevated TNF-alpha remain elusive. We hypothesized that autoamplification of TNF-alpha contributes to the maintenance of elevated TNF-alpha in obesity. Treatment of 3T3-L1 adipocytes with TNF-alpha, or injection of TNF-alpha into C57BL/6J mice, up-regulated TNF-alpha mRNA in adipocytes and in adipose tissues, respectively. Ob/ob male but not female mice lacking TNF-alpha receptors showed significantly lower levels of adipose TNF-alpha mRNA when compared with TNF-alpha receptor-expressing ob/ob mice. Thus, the lack of endogenous TNF-alpha signaling reduced adipose TNF-alpha mRNA in ob/ob male mice. Additionally, hyperinsulinemia potentiated this TNF-alpha-mediated autoamplification response in adipose tissues and in adipocytes in a synergistic and dose-dependent manner. Studies in which TNF-alpha was injected into lean mice lacking individual TNF-alpha receptors indicated that TNF-alpha autoamplification in adipose tissues was mediated primarily via the p55 TNF-alpha receptor whereas the p75 TNF-alpha receptor appeared to augment this response. Finally, TNF-alpha autoamplification in adipocytes occurred via the protein kinase C signaling pathway and the transcription factor nuclear factor-kappaB. Thus, TNF-alpha can positively autoregulate its own biosynthesis in adipose tissue, contributing to the maintenance of elevated TNF-alpha in obesity.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3 Cells
  • Adipocytes
  • Animals
  • Embryo, Mammalian
  • Female
  • Fibroblasts / metabolism
  • Gene Expression Regulation*
  • Homeostasis / genetics*
  • Hyperinsulinism / metabolism
  • Insulin / pharmacology
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Obese
  • Obesity / genetics
  • Obesity / metabolism*
  • Protein Kinase C / metabolism
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Receptors, Tumor Necrosis Factor, Type I / deficiency
  • Receptors, Tumor Necrosis Factor, Type I / genetics
  • Signal Transduction
  • Thinness / genetics
  • Tumor Necrosis Factor-alpha / genetics
  • Tumor Necrosis Factor-alpha / metabolism*


  • Insulin
  • RNA, Messenger
  • Receptors, Tumor Necrosis Factor, Type I
  • Tumor Necrosis Factor-alpha
  • Protein Kinase C