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Elastase from activated human neutrophils activates procarboxypeptidase R
Takeshi Kawamura1, Noriko Okada, Hidechika Okada
1Department of Biodefense, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, Japan.
Microbiology and Immunology
|May 15, 2002
Summary
Activated neutrophils generate carboxypeptidase R (CPR) from its zymogen (proCPR) primarily via elastase. This finding is crucial for understanding inflammation regulation and anaphylatoxin inactivation.
Area of Science:
- Biochemistry
- Immunology
- Protease research
Background:
- Carboxypeptidase R (CPR) is an unstable serum enzyme, distinct from stable carboxypeptidase N (CPN).
- Both CPR and CPN inactivate anaphylatoxins C3a and C5a by removing C-terminal arginine, thus regulating inflammation.
- ProCPR, the zymogen form, is activated during coagulation by thrombin-like enzymes.
Purpose of the Study:
- To investigate the role of activated human neutrophils in proCPR activation.
- To identify the specific enzymes released by neutrophils responsible for proCPR activation.
- To elucidate the mechanism by which neutrophils regulate CPR levels and, consequently, inflammation.
Main Methods:
- Culturing activated human neutrophils and collecting their supernatant.
- Assessing proCPR activation in the presence of neutrophil supernatant.
- Utilizing specific inhibitors for elastase (MSAAPVCK) and thrombin (pNP-pAPMS) to determine enzyme involvement.
- Testing purified elastase for its ability to activate proCPR.
Main Results:
- The supernatant of activated human neutrophils effectively converted proCPR to CPR.
- An elastase-specific inhibitor (MSAAPVCK) completely blocked proCPR activation by neutrophil supernatant.
- A thrombin-specific inhibitor showed minimal effect on proCPR activation.
- Purified elastase directly activated proCPR, indicating its direct role.
Conclusions:
- Neutrophil-derived elastase is a key enzyme responsible for activating proCPR.
- Neutrophils play a significant role in regulating CPR levels through elastase release.
- This mechanism is important for controlling excess inflammation by modulating anaphylatoxin activity.