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Synovial PMN show a coordinated up-regulation of CD66 molecules
M Hönig1, H H Peter, P Jantscheff
1Institute of Immunobiology, University of Freiburg, Germany.
Abstract:
Changes in the expression of various activation-dependent surface markers have been reported for polymorphonuclear neutrophils (PMN) isolated from synovial fluid of patients with inflammatory joint diseases. We extend these findings to the expression of CD66 molecules and several other surface markers. Three members of the CD66 family, namely CD66a, CD66b, and CD66c, showed an up to fourfold up-regulation on synovial fluid PMN compared with peripheral blood PMN (PBG) of the same patients; CD59 was increased twofold, the expression of CD16 did not change, whereas CD62L was reduced by more than 50% on synovial fluid PMN. It is interesting that CD66a, CD66b, and CD66c showed a coordinated expression on PBG of patients and controls and a coordinated up-regulation on synovial neutrophils. In contrast, after in vitro stimulation of peripheral blood PMN with phorbol myristate acetate, CD66c was much less up-regulated compared with CD66a and CD66b. All samples of synovial fluid PMN exhibited an additional increase in the expression of CD66a, CD66b, and CD66c when stimulated with phorbol myristate acetate in vitro. Prostaglandins are known to inhibit various responses of neutrophils to inflammatory stimuli. We could show that prostaglandins inhibit N-formyl-methionyl-leucyl-phenylalanine-induced up-regulation of CD66 on peripheral blood PMN in a concentration-dependent manner.
Insights
Polymorphonuclear neutrophils (PMN) in inflammatory joint diseases show altered CD66 expression. Synovial fluid PMN exhibit increased CD66a, CD66b, and CD66c levels, which are further enhanced by in vitro stimulation and modulated by prostaglandins.
Area of Science:
- Immunology
- Cell Biology
- Rheumatology
Background:
- Polymorphonuclear neutrophils (PMN) express surface markers indicating activation in inflammatory joint diseases.
- Previous studies noted changes in PMN activation markers in synovial fluid.
Purpose of the Study:
- To investigate the expression of CD66 molecules and other surface markers on synovial fluid PMN from patients with inflammatory joint diseases.
- To compare CD66 expression on synovial fluid PMN with peripheral blood PMN (PBG) and assess its modulation by in vitro stimulation and prostaglandins.
Main Methods:
- Flow cytometry was used to analyze the expression of CD66a, CD66b, CD66c, CD59, CD16, and CD62L on PMN.
- Peripheral blood PMN (PBG) and synovial fluid PMN (SF-PMN) were isolated from patients with inflammatory joint diseases and healthy controls.
- In vitro stimulation of PMN with phorbol myristate acetate (PMA) and N-formyl-methionyl-leucyl-phenylalanine (fMLP) was performed.
- The effect of prostaglandins on PMN activation markers was assessed.
Main Results:
- Synovial fluid PMN showed significantly higher expression of CD66a, CD66b, and CD66c (up to fourfold) compared to peripheral blood PMN.
- CD59 expression was increased twofold, while CD62L expression was reduced by over 50% on synovial fluid PMN.
- CD66a, CD66b, and CD66c displayed coordinated expression on peripheral blood PMN and coordinated up-regulation on synovial neutrophils.
- In vitro PMA stimulation led to less CD66c up-regulation compared to CD66a and CD66b on peripheral blood PMN, but further increased all three CD66 members on synovial fluid PMN.
- Prostaglandins inhibited N-formyl-methionyl-leucyl-phenylalanine-induced CD66 up-regulation on peripheral blood PMN in a concentration-dependent manner.
Conclusions:
- Synovial fluid PMN from patients with inflammatory joint diseases exhibit distinct changes in CD66 molecule expression, characterized by coordinated up-regulation of CD66a, CD66b, and CD66c.
- These changes suggest a role for CD66 molecules in neutrophil activation and function within the inflamed joint.
- Prostaglandins can modulate CD66 expression on neutrophils, potentially influencing inflammatory responses.