Grant: CIHR Fellowship

Despite advances in drug therapy and establishment of treatment guidelines, a significant proportion of health care expenditure, morbidity and excess mortality are related to a small but significant number of patients with severe and persistent asthma symptoms. Furthermore, even in patients with chronic asthma that are controlled by current therapy, there is a preference to try to minimize the amount of pharmaceuticals that patients require. We propose to use a new high resolution imaging technique, optical coherence tomography (OCT), to study the mechanism of chronic persistent asthma. Twenty subjects with chronic persistent asthma will undergo a new procedure known as bronchial thermoplasty to destroy the airway smooth muscle (ASM). Bronchial thermoplasty is a non-pharmaceutical clinically approved method for the treatment of uncontrolled asthma that ablates ASM and has been shown to reduce asthma symptoms. However, it is unclear exactly what structural changes occur within the airway wall following treatment and it is unclear why some subjects benefit from bronchial thermoplasy while others do not. The objective of this study will be to evaluate asthma subjects immediately prior to and immediately following bronchial thermoplasty as well as at week 18 and 52 post-thermoplasty. Airway wall measurements will be obtained using OCT which has been shown to be able to allow investigators to see epithelial and sub-epithelial structures such as ASM in-vivo with near microscopic resolution. By examining the changes in the airway wall that are caused by bronchial thermoplasty and comparing these changes before and after treatment with other clinical measurements we can describe the important airway wall structures responsible for the asthmatic response. We believe that these findings will allow us to discover novel pathways and candidate molecules that are targets for therapy and improve therapeutic options for patients with chronic persistent asthma.