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Mitochondrial dysfunction and HIF1alpha stabilization in inflammation

Assegid Garedew1, Salvador Moncada

  • 1The Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK.

Journal of Cell Science
|October 2, 2008
PubMed

Insights

Activated macrophages develop mitochondrial defects and increased glycolysis, driven by nitric oxide (NO) and HIF1alpha stabilization. This leads to an energy deficit, inhibiting cell proliferation and causing death.

Area of Science:

  • Cellular metabolism
  • Immunology
  • Mitochondrial function

Background:

  • Macrophages play crucial roles in immune responses.
  • Immune activation can significantly alter cellular energy metabolism.
  • Mitochondrial dysfunction is implicated in various cellular processes.

Purpose of the Study:

  • To investigate the impact of immune activation on macrophage mitochondrial function and energy production.
  • To elucidate the role of nitric oxide (NO) and hypoxia-inducible factor 1-alpha (HIF1alpha) in these metabolic changes.
  • To understand the consequences of metabolic alterations on macrophage proliferation and survival.

Main Methods:

  • Activation of J774.A1 macrophages using interferon gamma and lipopolysaccharide.
  • Measurement of oxygen consumption and ATP generation via oxidative phosphorylation.
  • Assessment of nitric oxide (NO) production and inducible NO synthase activity.
  • Analysis of hypoxia-inducible factor 1-alpha (HIF1alpha) stabilization.
  • Evaluation of glycolytic ATP production and cellular energy balance.

Main Results:

  • Macrophage activation induced mitochondrial defects, inhibiting oxygen consumption and oxidative phosphorylation-dependent ATP generation.
  • Nitric oxide (NO) production by inducible NO synthase was a key factor, consuming oxygen and contributing to mitochondrial dysfunction.
  • A biphasic stabilization of HIF1alpha was observed, with the second phase dependent on NO.
  • Mitochondrial defects and HIF1alpha stabilization synergistically activated glycolysis, increasing ATP production.
  • Despite enhanced glycolysis, the total ATP generated was insufficient for activated cells, leading to an energy deficit.

Conclusions:

  • Immune activation of macrophages leads to significant mitochondrial dysfunction and metabolic reprogramming.
  • Nitric oxide (NO) plays a critical role in mediating these metabolic changes and HIF1alpha stabilization.
  • The resulting energy deficit impairs macrophage proliferation and survival, highlighting the link between metabolism and cell fate.

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