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Chloroquine inhibits macrophage tumour necrosis factor-alpha mRNA transcription
Abstract:
Although chloroquine administration in vivo following haemorrhage in mice decreases tumour necrosis factor-alpha (TNF-alpha) release by macrophage (M phi), the mechanism remains unknown. To study this, peritoneal M phi (pM phi) from unmanipulated, sham-operated and post-haemorrhage mice were isolated, treated with 0.13 mg/ml chloroquine for 2 hr, and then stimulated with lipopolysaccharide (LPS) for 48 hr. Pretreatment of pM phi from various groups of mice with chloroquine resulted in 75-90% inhibition of TNF-alpha release, determined by bioassay. Total RNA was isolated from pM phi and murine M phi-derived cell lines (P388D1 and RAW 264.7), stimulated with LPS for 0.5 or 1 hr, respectively, and Northern blot analysis for TNF-alpha mRNA performed. Chloroquine inhibited TNF-alpha mRNA expression without interfering with mRNA stability, suggesting that this agent reduces M phi TNF-alpha release by disrupting TNF-alpha gene transcription.
Insights
Chloroquine significantly reduces tumor necrosis factor-alpha (TNF-alpha) release from macrophages. This occurs by inhibiting TNF-alpha gene transcription, not mRNA stability, following hemorrhage.
Area of Science:
- Immunology
- Pharmacology
- Molecular Biology
Background:
- Hemorrhage can lead to increased inflammatory responses.
- Macrophages (M phi) are key immune cells involved in inflammation.
- Tumor necrosis factor-alpha (TNF-alpha) is a critical pro-inflammatory cytokine.
Purpose of the Study:
- To elucidate the mechanism by which chloroquine reduces TNF-alpha release from macrophages post-hemorrhage.
- To investigate the effect of chloroquine on TNF-alpha gene transcription and mRNA stability.
Main Methods:
- Isolation of peritoneal macrophages (pM phi) from mice under different conditions (unmanipulated, sham-operated, post-hemorrhage).
- In vitro treatment of macrophages with chloroquine followed by lipopolysaccharide (LPS) stimulation.
- Bioassay to measure TNF-alpha release and Northern blot analysis to assess TNF-alpha mRNA expression and stability.
Main Results:
- Chloroquine pretreatment inhibited TNF-alpha release by 75-90% in macrophages from all experimental groups.
- Chloroquine treatment suppressed TNF-alpha mRNA expression.
- Chloroquine did not affect the stability of TNF-alpha mRNA.
Conclusions:
- Chloroquine reduces macrophage-mediated TNF-alpha release by inhibiting TNF-alpha gene transcription.
- This mechanism is effective in macrophages from both normal and post-hemorrhage states.
- Findings suggest a novel therapeutic target for managing inflammation associated with hemorrhage.