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.