Opposite regulation of IL-1beta and secreted IL-1 receptor antagonist production by phosphatidylinositide-3 kinases in human monocytes activated by lipopolysaccharides or contact with T cells

J Immunol. 2007 Jan 1;178(1):446-54. doi: 10.4049/jimmunol.178.1.446.

Abstract

The unbalanced production of IL-1beta and its natural, specific inhibitor, the secreted IL-1R antagonist (sIL-1Ra), plays an important role in chronic/sterile inflammation. Relevant to this condition is direct cellular contact with stimulated T cells which is a potent inducer of cytokine production in human monocytes/macrophages. We previously demonstrated that activation of PI3Ks is a prerequisite of the transcription of the sIL-1Ra gene in human monocytes activated by IFN-beta. In this study, we addressed the question of PI3K involvement in the production of IL-1beta and sIL-1Ra in monocytes activated by cellular contact with stimulated T cells (mimicked by CHAPS-solubilized membranes of stimulated T cells (CE(sHUT))), and a crude preparation of LPS, to compare stimuli relevant to chronic/sterile and acute/infectious inflammation, respectively. In monocytes activated by either CE(sHUT) or LPS, the inhibition of PI3Ks abrogated sIL-1Ra transcript expression and sIL-1Ra production, demonstrating that PI3Ks control the induction of sIL-1Ra gene transcription. In contrast, PI3K inhibition increased the production of IL-1beta protein in both CE(sHUT)- and LPS-activated monocytes, the enhancement being drastically higher in the former. This was not due to changes in IL-1beta mRNA steady-state levels or transcript stability, but to the involvement of PI3Ks in the repression of IL-1beta secretion. The downstream PI3K effector, Akt, was implicated in this process. The present results demonstrate that PI3Ks are involved in the inhibition of IL-1beta secretion and in the induction of sIL-1Ra production in human blood monocytes by controlling different mechanisms in conditions mimicking chronic/sterile (CE(sHUT)) and acute/infectious (LPS) inflammation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Down-Regulation
  • Gene Expression Regulation
  • Humans
  • Interleukin 1 Receptor Antagonist Protein / genetics
  • Interleukin 1 Receptor Antagonist Protein / metabolism*
  • Interleukin-1beta / genetics
  • Interleukin-1beta / metabolism*
  • Lipopolysaccharides / pharmacology
  • Monocytes / drug effects
  • Monocytes / immunology*
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphoinositide-3 Kinase Inhibitors
  • Proto-Oncogene Proteins c-akt / metabolism
  • RNA Stability
  • RNA, Messenger / metabolism
  • T-Lymphocytes / immunology
  • Transcription, Genetic
  • Up-Regulation

Substances

  • Interleukin 1 Receptor Antagonist Protein
  • Interleukin-1beta
  • Lipopolysaccharides
  • Phosphoinositide-3 Kinase Inhibitors
  • RNA, Messenger
  • Proto-Oncogene Proteins c-akt