Neutrophil Proteases Activate Eosinophil Function in vitro.
BACKGROUND
Recent evidence suggests that both neutrophilic and eosinophilic inflammation persist in the airways of patients with severe asthma. Mechanisms for interaction between neutrophils and eosinophils are still to be understood. Since eosinophils express protease-activated receptor 2, neutrophil-derived serine proteases may activate eosinophils.


OBJECTIVE
We investigated the effect of neutrophil serine proteases on eosinophil effector functions.


METHODS
Peripheral blood eosinophils were stimulated with elastase, cathepsin G and proteinase 3. Superoxide generation was quantitated with the cytochrome C reduction method. A panel of cytokines and chemokines in the culture supernatants were measured with a multiplex beads array system. Effects of an elastase inhibitor, sivelestat, and a serine protease inhibitor, PMSF, on the protease-induced reactions were also tested.


RESULTS
Neutrophil proteases significantly induced superoxide production from eosinophils. Elastase was the most potent among them. Sivelestat and PMSF inhibited the reaction. The proteases induced production of IL-6, IL-8, TNF-alpha and GRO-alpha, that have a possible connection with neutrophilic inflammation.


CONCLUSIONS
Neutrophil proteases activate eosinophils to produce superoxide, proinflammatory cytokines and neutrophilotactic chemokines and may further aggravate airway inflammation in patients with severe asthma.
Hiraguchi
Yukiko
Y
Institute for Clinical Research, Mie National Hospital, Mie, Japan.
Nagao
Mizuho
M
Hosoki
Koa
K
Tokuda
Reiko
R
Fujisawa
Takao
T
D056649:Cathepsin G; D002403:Cathepsins / Q000378:metabolism* / Q000494:pharmacology; D002478:Cells, Cultured; D018925:Chemokines / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D004804:Eosinophils / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D009504:Neutrophils / Q000201:enzymology / Q000276:immunology*; D010196:Pancreatic Elastase / Q000378:metabolism* / Q000494:pharmacology; D012697:Serine Endopeptidases / Q000378:metabolism* / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism
D018925:Chemokines; D016207:Cytokines; D013481:Superoxides; D002403:Cathepsins; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G; D010196:Pancreatic Elastase