Related Experiment Video
Updated: Jul 7, 2026
Isolation Protocol of Mouse Monocyte-derived Dendritic Cells and Their Subsequent In Vitro Activation with Tumor Immune Complexes
Published on: May 31, 2018
Hypoxia modulates lipopolysaccharide induced TNF-alpha expression in murine macrophages
Feng Qin Liu1, Yan Liu, Vincent C H Lui
1Division of Paediatric Surgery, Department of Surgery, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, PR China.
Abstract:
The pro-inflammatory activity of Tumor necrosis factor-alpha (TNF-alpha) together with tissue hypoxia determine the clinical outcome in sepsis and septic shock. p38 MAPKinase is the primary intracellular signaling pathway that regulates lipopolysaccharide (LPS)-induced TNF-alpha biosynthesis, however, the effect of hypoxia on LPS mediated activation of p38 is not known. Here we report that SB203580, a specific p38 MAPK inhibitor, which completely abolished LPS-induced TNF-alpha expression by the mouse macrophage cell RAW264.7 in normoxic conditions, lost the inhibitory effect in hypoxic conditions. Hypoxia did not modulate expression of p38 MAPK, but increased that of p-MK2, a downstream target of p38 MAPK. In LPS induced endotoxemia mice model SB203580 had no inhibitory effect on the serum levels of TNF-alpha. Furthermore, hypoxia inducible factor-1alpha (HIF-1alpha) was detected in vivo after LPS administration but its expression was not affected by SB203580. Our data indicate that LPS induced p38 MAPK activation was enhanced by hypoxia and consequently increased TNF-alpha secretion. Furthermore, the induction of HIF-1alpha in mice with endotoxemia suggested a synergistic effect on p38 mediated TNF-alpha expression. These findings provide new insights on the pathophysiological effects of hypoxia in sepsis and septic shock.
Insights
Hypoxia enhances lipopolysaccharide (LPS)-induced Tumor Necrosis Factor-alpha (TNF-alpha) production by activating p38 MAPK. This suggests hypoxia worsens sepsis outcomes by boosting inflammatory responses.
Area of Science:
- Cellular and Molecular Biology
- Immunology
- Pathophysiology
Background:
- Sepsis and septic shock involve pro-inflammatory Tumor Necrosis Factor-alpha (TNF-alpha) and tissue hypoxia.
- p38 MAPK regulates TNF-alpha biosynthesis, but hypoxia's effect on this pathway is unclear.
Purpose of the Study:
- To investigate the impact of hypoxia on lipopolysaccharide (LPS)-mediated p38 MAPK activation and subsequent TNF-alpha production.
Main Methods:
- Used RAW264.7 macrophage cells and an LPS-induced endotoxemia mouse model.
- Administered SB203580, a p38 MAPK inhibitor, under normoxic and hypoxic conditions.
- Assessed TNF-alpha, p38 MAPK, p-MK2, and hypoxia-inducible factor-1alpha (HIF-1alpha) expression.
Main Results:
- SB203580 inhibited LPS-induced TNF-alpha in normoxia but not hypoxia.
- Hypoxia increased p-MK2 expression, a p38 MAPK target, without altering p38 MAPK levels.
- In vivo, SB203580 failed to inhibit serum TNF-alpha in LPS-treated mice; HIF-1alpha was induced.
- LPS-induced p38 MAPK activation was enhanced by hypoxia, leading to increased TNF-alpha secretion.
Conclusions:
- Hypoxia potentiates LPS-induced p38 MAPK activation and TNF-alpha secretion.
- HIF-1alpha induction in endotoxemia suggests a synergistic effect with p38 MAPK on TNF-alpha expression.
- Findings offer new insights into hypoxia's role in sepsis pathophysiology.
