This study aims to investigate the effect of omalizumab on the number of tissue eosinophils and other markers of airway inflammation and remodeling, including thickness of the lamina reticularis, in moderate to severe asthmatics with persistent symptoms and evidence of airway inflammation despite treatment with inhaled corticosteroids and long acting beta-agonists. This study will also investigate the correlation between systemic and pulmonary inflammation, and the correlation between clinical outcomes and changes within the tissue, to assist in the future identification of patients with tissue eosinophilia and their response to treatment, without the need for invasive bronchoscopy.