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Low density lipoprotein activates monocytes to express tumor necrosis factor
P Barath1, J Cao, J S Forrester
1Cedars-Sinai Medical Center, Division of Cardiology, Los Angeles, California.
FEBS Letters
|December 17, 1990
Summary
This study shows acetylated low density lipoprotein (aLDL) significantly increases tumor necrosis factor (TNF) mRNA and protein in human monocytes. This suggests aLDL plays a role in inflammatory processes like atheroma development.
Area of Science:
- Immunology
- Cardiovascular Research
- Molecular Biology
Background:
- Monocytes are key immune cells involved in inflammation.
- Tumor Necrosis Factor (TNF) is a pro-inflammatory cytokine.
- Dysregulated lipid metabolism, particularly oxidized LDL, is implicated in atherosclerosis.
Purpose of the Study:
- To investigate the impact of acetylated low density lipoprotein (aLDL) on TNF expression in human monocytes.
- To elucidate the role of aLDL in monocyte-mediated inflammatory responses relevant to atheroma.
Main Methods:
- Isolated human monocytes were incubated with varying concentrations of aLDL in serum-free DMEM.
- TNF mRNA expression was quantified using established molecular biology techniques.
- TNF protein levels were assessed using immunoassays.
- Time-course and dose-response experiments were conducted.
Main Results:
- aLDL dose-dependently stimulated TNF mRNA expression, with maximal effect at 250 µg/ml and downregulation at 500 µg/ml.
- Peak TNF mRNA levels were observed at 6 hours, returning to baseline by 24 hours.
- aLDL induced a sevenfold increase in immunoreactive TNF protein by 12 hours after a 6-hour exposure.
Conclusions:
- aLDL is a potent stimulator of TNF-α mRNA and protein expression in resting human monocytes.
- This mechanism highlights a potential role for aLDL in the inflammatory processes driving atheroma evolution.