Neutrophil Proteases Activate Eosinophil Function in vitro.

Area of Science:

• Immunology
• Respiratory Medicine
• Cell Biology

Background:

• Severe asthma involves persistent neutrophilic and eosinophilic airway inflammation.
• The interaction mechanisms between neutrophils and eosinophils remain unclear.
• Eosinophils express protease-activated receptor 2, suggesting potential activation by neutrophil proteases.

Purpose of the Study:

• To investigate the impact of neutrophil serine proteases on eosinophil effector functions.
• To understand how neutrophil proteases influence eosinophil activity in severe asthma.

Main Methods:

• Eosinophils were stimulated with neutrophil serine proteases (elastase, cathepsin G, proteinase 3).
• Superoxide generation was measured using the cytochrome C reduction method.
• Cytokine and chemokine production was analyzed via multiplex beads array.
• Inhibitors (sivelestat, PMSF) were used to block protease activity.

Main Results:

• Neutrophil proteases significantly induced eosinophil superoxide production, with elastase being most potent.
• Protease-induced reactions were inhibited by sivelestat and PMSF.
• Induced cytokines included IL-6, IL-8, TNF-alpha, and GRO-alpha, potentially linking to neutrophilic inflammation.

Conclusions:

• Neutrophil proteases activate eosinophils, leading to superoxide production.
• Activated eosinophils release proinflammatory cytokines and neutrophilotactic chemokines.
• These interactions may exacerbate airway inflammation in severe asthma patients.