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Human apoA-I increases macrophage foam cell derived PLTP activity without affecting the PLTP mass
Marius R Robciuc1, Jari Metso, Anca Sima
1National Institute for Health and Welfare, Public Health Genomics Research Unit and FIMM, Institute for Molecular Medicine Finland, Helsinki, Finland. marius.robciuc@thl.fi
Lipids in Health and Disease
|June 11, 2010
Summary
High-density lipoprotein (HDL) apolipoprotein A-I (apoA-I) enhances phospholipid transfer protein (PLTP) activity from macrophage foam cells. This finding is crucial for understanding lipoprotein metabolism and atherosclerosis progression.
Area of Science:
- Biochemistry
- Cell Biology
- Cardiovascular Research
Background:
- Phospholipid transfer protein (PLTP) is vital in lipoprotein metabolism and atherosclerosis.
- PLTP is expressed by macrophages and macrophage foam cells (MFCs).
Purpose of the Study:
- To investigate the effect of apolipoprotein A-I (apoA-I), a major HDL protein, on PLTP derived from MFCs.
Main Methods:
- Human THP-1 monocytes were differentiated into MFCs using acetylated LDL.
- The impact of apoA-I on apoE secretion, PLTP synthesis, secretion, and activity was assessed.
- Phospholipid transfer activity of PLTP was measured in cell media and isolated human plasma PLTP.
Main Results:
- ApoA-I increased apoE secretion from MFCs in a concentration-dependent manner.
- ApoA-I did not affect PLTP synthesis or secretion but significantly enhanced PLTP activity in the media.
- ApoA-I also boosted phospholipid transfer activity of plasma PLTP and protected it from heat inactivation.
Conclusions:
- ApoA-I enhances the phospholipid transfer activity of PLTP secreted by macrophage foam cells.
- This enhancement occurs without altering the PLTP mass, suggesting a post-translational modification or interaction.
