C-reactive protein products generated by neutrophil elastase promote neutrophil apoptosis.
BACKGROUND
C-reactive protein (CRP), a prototypical acute phase protein, is increased as much as 1000-fold during acute inflammation, suggesting its biological role in that process. CRP can be modified at sites of inflammation where proteases have been released by neutrophils migrating to tissues. In this study, we investigated whether native CRP and neutrophil elastase-digested products of CRP modulate the rate of neutrophil apoptosis.


METHODS
Neutrophils were isolated from venous blood of healthy volunteers and incubated with either native CRP (1, 10, or 30 microg/mL) or CRP digested with neutrophil elastase (1 U/mL). After 6 and 24 h of incubation, neutrophils were harvested and examined for apoptosis under light microscopy.


RESULTS
We found that CRP degradation products generated by neutrophil elastase, but not native CRP, promoted neutrophil apoptosis and cell death. The rate of apoptosis was not affected by the addition of elastase that was not incubated with CRP.


CONCLUSIONS
These results suggest that CRP degradation products generated by neutrophil elastase promote neutrophil apoptosis. Cleavage of CRP by neutrophil elastase may offer protection from inflammatory injury.
Kakuta
Yumi
Y
First Department of Medicine, Tokyo Women's Medical University, Tokyo, Japan.
Aoshiba
Kazutetsu
K
Nagai
Atsushi
A
D017209:Apoptosis / Q000187:drug effects*; D002097:C-Reactive Protein / Q000378:metabolism* / Q000494:pharmacology*; D002478:Cells, Cultured; D006801:Humans; D019272:Leukocyte Elastase / Q000378:metabolism*; D009504:Neutrophils / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology
D010446:Peptide Fragments; D002097:C-Reactive Protein; D019272:Leukocyte Elastase