The pro-inflammatory cytokine IL-18 is expressed in human adipose tissue and strongly upregulated by TNFalpha in human adipocytes

Biochem Biophys Res Commun. 2005 Nov 18;337(2):422-9. doi: 10.1016/j.bbrc.2005.09.068. Epub 2005 Sep 21.

Abstract

White adipocytes have been examined as a potential source of interleukin-18 (IL-18), the circulating levels of which are increased in obesity. IL-18 gene expression was evident in human subcutaneous and visceral adipose tissue, and expression occurred in mature adipocytes and the stromal-vascular fraction. Expression of the IL-18 receptor complex (IL-18Ralpha and IL-18Rbeta) and the IL-18 binding protein (IL-18BP) genes was also observed, mirroring that of IL-18. IL-18 mRNA level increased rapidly (within 2h) and dramatically (>900-fold) in response to TNFalpha in human adipocytes differentiated in culture. IL-18 protein was detected in lysates of cultured adipocytes, though not in the medium. There was a small increase in IL-18 in lysates of adipocytes treated with TNFalpha, but the protein was again undetectable in the medium. IL-18 may be part of the inflammatory cascade within adipose tissue; however, human adipocytes do not appear to secrete significant amounts of IL-18.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipocytes / drug effects*
  • Adipocytes / metabolism
  • Adipose Tissue / cytology
  • Adipose Tissue / metabolism*
  • Base Sequence
  • Cytokines / metabolism
  • Gene Expression / drug effects*
  • Humans
  • Inflammation / genetics
  • Inflammation / metabolism
  • Interleukin-18 / metabolism*
  • RNA, Messenger / analysis
  • RNA, Messenger / metabolism
  • Time Factors
  • Tumor Necrosis Factor-alpha / pharmacology*
  • Up-Regulation

Substances

  • Cytokines
  • Interleukin-18
  • RNA, Messenger
  • Tumor Necrosis Factor-alpha