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Distinct scavenger receptor expression and function in the human CD14(+)/CD16(+) monocyte subset.
G Draude1, P von Hundelshausen, M Frankenberger
1Institut für Prophylaxe der Kreislaufkrankheiten, Klinikum Innenstadt, Ludwig-Maximilians-Universität, D-80336 Munich, Germany.
The American Journal of Physiology
|April 13, 1999
Summary
The CD14(+)/CD16(+) monocyte subset exhibits reduced scavenger receptor (ScR) function and expression, potentially impacting lipid accumulation in inflammatory conditions like atherosclerosis.
Area of Science:
- Immunology
- Cell Biology
- Vascular Biology
Background:
- The CD14(+)/CD16(+) monocyte subset displays characteristics of mature macrophages and is implicated in inflammatory diseases and atherosclerosis.
- Scavenger receptors (ScR) are crucial for lipid uptake in foam cells during atherogenesis and pathogen clearance.
Purpose of the Study:
- To compare scavenger receptor (ScR) function and expression between CD33(low) CD16(+) and CD33(high) CD14(++) monocyte subsets.
- To investigate the role of these monocyte subsets in the context of atherogenesis and inflammatory conditions.
Main Methods:
- Double immunofluorescence analysis of isolated human blood monocytes.
- Scavenger receptor-mediated binding assays using DiI-labeled modified low-density lipoproteins (LDL).
- Reverse transcription-polymerase chain reaction (RT-PCR) to quantify scavenger receptor mRNA expression (ScR-AI/II and CD36).
Main Results:
- The CD33(low) CD14(+)/CD16(+) monocyte subset demonstrated significantly lower ScR-mediated binding of modified LDL compared to the CD33(high) CD14(++) subset.
- mRNA expression analysis revealed lower ScR class A type I/II (ScR-AI/II) levels in CD14(+)/CD16(+) monocytes, while CD36 transcripts remained unchanged.
- In vitro studies with CD16(+) monocyte-derived macrophages showed reduced ScR-mediated binding of acetylated LDL and lower ScR-AI/II mRNA expression after TNF-alpha exposure.
Conclusions:
- The CD14(+)/CD16(+) monocyte subset possesses distinct ScR function and expression profiles.
- These differences suggest a potential preactivation state in this monocyte subset, influencing their role in inflammatory and vascular diseases such as atherosclerosis.