Superoxide attenuates macrophage apoptosis by NF-kappa B and AP-1 activation that promotes cyclooxygenase-2 expression

J Immunol. 1999 Sep 1;163(5):2858-66.

Abstract

Macrophages are a major source of cytokines and proinflammatory radicals such as superoxide. These mediators can be both produced and utilized by macrophages in autocrine-regulatory pathways. Therefore, we studied the potential role of oxygen radical-regulatory mechanisms in reprogramming macrophage apoptosis. Preactivation of RAW 264.7 cells with a nontoxic dose of the redox cycler 2,3-dimethoxy-1,4-naphthoquinone (5 microM) for 15 h attenuated S-nitrosoglutathione (1 mM)-initiated apoptotic cell death and averted accumulation of the tumor suppressor p53, which is indicative for macrophage apoptosis. Preactivation with superoxide promoted cyclooxygenase-2 induction that was NF-kappa B and AP-1 mediated. NF-kappa B activation was confirmed by p50/p65-heterodimer formation, I kappa B-alpha degradation, and stimulation of a NF-kappa B luciferase reporter construct. Furthermore, a NF-kappa B decoy approach abrogated cyclooxygenase-2 (Cox-2) expression as well as inducible protection. The importance of AP-1 for superoxide-mediated Cox-2 expression and cell protection was substantiated by using the extracellular signal-regulated kinase-inhibitor PD98059 and the p38-inhibitor SB203580, which blocked Cox-2 expression. In corroboration, Cox-2 expression was hindered by a dominant-negative c-jun mutant (TAM67). Protection from apoptosis was verified in human macrophages with the notion that superoxide promoted Cox-2 expression, which in turn attenuated nitric oxide-evoked caspase activation. We conclude that the sublethal generation of oxygen radicals reprograms macrophages by NF-kappa B and AP-1 activation. The resulting hyporesponsiveness reveals an attenuated apoptotic program in association with Cox-2 expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adjuvants, Immunologic / pharmacology*
  • Animals
  • Apoptosis / drug effects
  • Apoptosis / immunology*
  • Cell Line
  • Cyclooxygenase 2
  • Dose-Response Relationship, Drug
  • Isoenzymes / biosynthesis*
  • Isoenzymes / metabolism
  • Macrophages / cytology
  • Macrophages / drug effects
  • Macrophages / enzymology*
  • Macrophages / metabolism
  • Mice
  • NF-kappa B / metabolism*
  • NF-kappa B / physiology
  • Naphthoquinones / pharmacology
  • Nitric Oxide / physiology
  • Prostaglandin-Endoperoxide Synthases / biosynthesis*
  • Prostaglandin-Endoperoxide Synthases / metabolism
  • Superoxides / pharmacology*
  • Transcription Factor AP-1 / metabolism*
  • Transcription Factor AP-1 / physiology
  • Tumor Suppressor Protein p53 / metabolism

Substances

  • Adjuvants, Immunologic
  • Isoenzymes
  • NF-kappa B
  • Naphthoquinones
  • Transcription Factor AP-1
  • Tumor Suppressor Protein p53
  • Superoxides
  • Nitric Oxide
  • 2,3-dimethoxy-1,4-naphthoquinone
  • Cyclooxygenase 2
  • Prostaglandin-Endoperoxide Synthases