Novel asthma biomarkers to predict the response to inhaled corticosteroid Brief description: This will be a single center study of asthmatic subjects and healthy controls which will investigate mechanisms underlying different response to inhaled corticosteroid, the mainstay of asthma therapy. Only about half of the asthmatic patients have improved lung function after treatment of inhaled corticosteroid. The investigators hypothesize that there are biomarkers such as epithelial cytokines (IL-25, IL-33, TSLP) in airway tissues or plasma of asthmatic patients which could predict the response of asthmatic patients to inhaled corticosteroid. Finding novel asthma biomarker will help the clinicians to choose the optimal treatment for individual asthmatic patient.

Group A:

Inclusion Criteria:

• Male and female subjects between the ages of 18 and 70 years
• No respiratory symptoms
• Normal spirometric value and methacholine PD20 >2.5mg

Group B:

Inclusion Criteria:

• Male and female subjects between the ages of 18 and 70 years
• History of asthma
• No use of oral or inhaled corticosteroids for the treatment of asthma
• No use of leukotriene antagonist for the treatment of asthma
• Hyperreactivity to methacholine (PD20 FEV1 Methacholine < 2.5 mg) and/or ≥12% increase in FEV1 following inhalation of 200μg salbutamol
• Asthma symptoms of episodic cough, wheeze and/or breathlessness

Exclusion Criteria:

• Current or former smokers
• Pregnant women
• Subjects with a history of lung disease other than asthma
• Subjects with a history of a medical disease, which in the opinion of the investigator may put the subject at extra risk from study-related procedures or because the disease may influence the results of the study