Association between neutrophilic and eosinophilic inflammation in patients with severe persistent asthma.
BACKGROUND
Eosinophils are generally recognized as effector cells in asthma. Recently, neutrophils have been suggested to contribute to the development of chronic severe asthma. The mechanisms by which neutrophils contribute to the pathophysiology of asthma remain to be elucidated; however, neutrophils may affect either accumulation or functional status of eosinophils via the generation of inflammatory mediators. The objective of this study was to evaluate whether neutrophilic inflammation is associated with eosinophilic inflammation in severe asthma.


METHODS
Following the inhalation of hypertonic saline, induced sputum was obtained from 12 healthy controls, 10 mild persistent asthmatics who were treated with low-dose inhaled corticosteroids, and 8 severe persistent asthmatics who were treated with combinations of drugs including high-dose inhaled corticosteroids and oral prednisolone. Subsequently, differential inflammatory cell counts were evaluated.


RESULTS
The percentage of eosinophils in induced sputum was significantly higher in patients who showed airway neutrophilia. In severe persistent asthmatics, the percentage of neutrophils was significantly correlated with the percentage of eosinophils in induced sputum.


CONCLUSIONS
The results of the present study suggest that accumulated neutrophils may contribute to the development of eosinophilic inflammation in severe persistent asthmatics who were treated with oral and high-dose inhaled corticosteroids. This effect may contribute to the eventual manifestation of airway inflammation in severe asthma.
Kikuchi
Shinya
S
Department of Respiratory Medicine, Saitama Medical School, Japan.
Nagata
Makoto
M
Kikuchi
Izumi
I
Hagiwara
Koichi
K
Kanazawa
Minoru
M
D000328:Adult; D000730:Androstadienes / Q000627:therapeutic use; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use; D001249:Asthma / Q000188:drug therapy / Q000276:immunology*; D002452:Cell Count; D004804:Eosinophils / Q000166:cytology / Q000276:immunology*; D005260:Female; D000068298:Fluticasone; D006801:Humans; D008297:Male; D008875:Middle Aged; D009504:Neutrophils / Q000166:cytology / Q000276:immunology*; D011239:Prednisolone / Q000627:therapeutic use; D013183:Sputum / Q000166:cytology / Q000276:immunology
D000730:Androstadienes; D018927:Anti-Asthmatic Agents; D011239:Prednisolone; D000068298:Fluticasone