Angiopoietin-2 as a contributing factor of exercise-induced bronchoconstriction in asthmatic patients receiving inhaled corticosteroid therapy.
BACKGROUND
Airway microcirculation has the potential to contribute to the pathogenesis of exercise-induced bronchoconstriction (EIB) in asthma. Recently, angiopoietin-1 has been found to stabilize microvessels and make them leak resistant, whereas angiopoietin-2 is an antagonist of angiopoietin-1 and enhances microvascular permeability.


OBJECTIVE
We sought to examine the roles of angiopoietin-2 in EIB in asthmatic patients with inhaled corticosteroid therapy.


METHODS
Levels of angiopoietin-1 and angiopoietin-2 in induced sputum were examined in 32 asthmatic patients who were receiving inhaled corticosteroid therapy for more than 6 months at the entry of this study and 14 healthy control subjects. All asthmatic patients performed an exercise test.


RESULTS
The degree of eosinophilic airway inflammation did not differ significantly between asthmatic patients and healthy control subjects. Angiopoietin-1 levels were also similar in the 2 groups (asthmatic patients: median, 6.0 ng/mL [range, 2.0-10.7 ng/mL]; healthy control subjects: median, 4.2 ng/mL [range, 1.5-10.7 ng/mL]). In contrast, angiopoietin-2 levels were significantly higher in asthmatic patients than in healthy control subjects (asthmatic patients: median, 0.74 ng/mL [range, 0.3-1.2 ng/mL]; healthy control subjects: median, 0.26 ng/mL [range, 0.05-0.47 ng/mL]; P < .001). There was no significant correlation between angiopoietin-1 levels and the severity of EIB in asthmatic patients. However, angiopoietin-2 levels were significantly correlated with the severity of EIB and airway microvascular permeability index.


CONCLUSIONS
Angiopoietin-2 levels were increased in the airways of asthmatic patients with inhaled corticosteroid therapy, and its levels were associated with the severity of EIB.
Kanazawa
Hiroshi
H
Department of Respiratory Medicine, Graduate School of Medicine, Osaka City University, Osaka, Japan. kanazawa-h@med.osaka-cu.ac.jp
Tochino
Yoshihiro
Y
Asai
Kazuhisa
K
D000280:Administration, Inhalation; D000305:Adrenal Cortex Hormones / Q000008:administration & dosage* / Q000627:therapeutic use; D000328:Adult; D042702:Angiopoietin-2 / Q000378:metabolism*; D001249:Asthma / Q000188:drug therapy / Q000378:metabolism / Q000503:physiopathology*; D001980:Bronchi / Q000098:blood supply; D016084:Bronchoconstriction; D002199:Capillary Permeability; D015444:Exercise; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008833:Microcirculation; D012720:Severity of Illness Index; D013183:Sputum / Q000378:metabolism*
D000305:Adrenal Cortex Hormones; D042702:Angiopoietin-2