Bronchial inflammation in corticosteroid-sensitive and corticosteroid-resistant asthma at baseline and on oral corticosteroid treatment.
BACKGROUND
Pathophysiology of corticosteroid (CS)-resistant asthma remains incompletely understood.


OBJECTIVE
To determine if failure of asthma to clinically improve with CS is due to a defective response of airway bronchial inflammation to these drugs.


METHODS
Twenty-one asthmatics having a decreased baseline FEV1 that improved >or= 30% with inhaled beta2 agonist got bronchial biopsies before and at the end of an oral CS treatment (methylprednisolone 40 mg daily for 14 days). They were arbitrarily divided into two groups according to baseline FEV1 improvement following this treatment: >or= 23% designated as CS-sensitive (CSS) (n = 10) and < 15% as CS-resistant (CSR) (n = 11).


RESULTS
Before oral CS, counts of bronchial mucosa inflammatory cells identified by immunohistochemistry (CD3, MBP, tryptase, CD68, neutrophil elastase and CD25 for lymphocytes, eosinophils, mast cells, macrophages, neutrophils and IL-2 receptors, respectively) were similar in CSS and CSR subjects. Oral CS decreased CD3+ cell counts (medians: 60-20 cells/mm(2); P = 0.014) and MBP+ cell counts (medians: 19-4 cells/mm(2); P = 0.03) in CSS asthmatics, but only tryptase+ cell counts in CSR asthmatics (medians: 30-18 cells/mm(2); P = 0.05). Few bronchial neutrophil elastase+ cells were observed and their counts were similar in the two groups of asthmatics before and when on oral CS (all medians: = 2 cells/mm(2)).


CONCLUSIONS
These data show that, in these subjects with moderate to severe asthma, lymphocytes and eosinophils constitute most of the inflammatory cells infiltrating the bronchial mucosa. They also demonstrated that clinical impaired response to CS is associated with a persistent bronchial mucosa cellular infiltrate despite oral CS treatment. Additional studies are required to determine the role of this CS-resistant bronchial inflammation in the impaired asthma clinical response to these drugs.
Chakir
J
J
Unité de Recherche en Pneumologie, Centre de Recherche de l'Hôpital Laval, Institut Universitaire de Cardiologie et de Pneumologie de l'Université Laval, Sainte-Foy, Québec, Canada. jamila.chakir@med.ulaval.ca
Hamid
Q
Q
Bossé
M
M
Boulet
L-P
LP
Laviolette
M
M
D000280:Administration, Inhalation; D000284:Administration, Oral; D058666:Adrenergic beta-2 Receptor Agonists; D000318:Adrenergic beta-Agonists / Q000008:administration & dosage; D000328:Adult; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D001249:Asthma / Q000175:diagnosis / Q000188:drug therapy* / Q000276:immunology*; D001980:Bronchi / Q000276:immunology*; D005260:Female; D005541:Forced Expiratory Volume; D005938:Glucocorticoids / Q000008:administration & dosage / Q000627:therapeutic use*; D006801:Humans; D007249:Inflammation / Q000276:immunology; D007958:Leukocyte Count; D008297:Male; D008775:Methylprednisolone / Q000008:administration & dosage / Q000627:therapeutic use*; D020545:Respiratory Mucosa / Q000276:immunology
D058666:Adrenergic beta-2 Receptor Agonists; D000318:Adrenergic beta-Agonists; D000893:Anti-Inflammatory Agents; D005938:Glucocorticoids; D008775:Methylprednisolone