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Eosinophilic leukocyte accumulation during vagally induced bronchoconstriction
1Respiratory Health Network of Center of Excellence, University of British Columbia, St. Paul's Hospital, Vancouver, Canada.
American Journal of Respiratory and Critical Care Medicine
|December 31, 1997
Summary
Bronchoconstriction in asthma causes eosinophils to accumulate in the airway inner wall due to geometric changes. Atropine blocked this eosinophil accumulation, suggesting a role for vagus nerve stimulation.
Area of Science:
- Pulmonary immunology
- Respiratory physiology
Background:
- Eosinophils are key cells in allergic inflammation, particularly in asthma.
- Their accumulation in bronchial mucosa is known, but the link to bronchoconstriction is unclear.
Purpose of the Study:
- To investigate the relationship between bronchoconstriction and eosinophil accumulation in airway walls.
- To test the hypothesis that geometric changes during bronchoconstriction retain eosinophils in the bronchial vasculature.
Main Methods:
- Unilateral bronchoconstriction was induced in guinea pigs via vagus nerve stimulation.
- Eosinophil density in constricted and unconstricted airways was compared using histological analysis.
- Relationships between smooth muscle shortening and eosinophil density were assessed.
Main Results:
- Eosinophil density significantly increased in the inner airway wall and decreased in the adventitia of constricted airways.
- Smooth muscle shortening positively correlated with inner wall eosinophil density and negatively with adventitial density.
- Atropine administration completely inhibited eosinophil accumulation in the inner airway wall.
Conclusions:
- Geometric factors, specifically mucosal membrane deformation during bronchoconstriction, contribute to eosinophil accumulation in the airway inner wall.
- Vagus nerve stimulation, mediated by acetylcholine, plays a role in this eosinophil recruitment process.