Advanced endoscopic imaging in small airway disease : confocal laser endomicroscopy in emphysema and after lung transplantation

Abstract

Chronic Obstructive Pulmonary Disease (COPD) occurs in 10% of the adult population and is currently the 4th leading cause of mortality. The associated morbidity, the economic burden as well as the societal impact of COPD is huge and one of the major health challenges of the future. COPD is characterized by progressive and irreversible airflow limitation and it is shown that these changes start at the level of the small airways even before symptoms occur. Long term survival after lung transplantation is mainly determined by the presence/absence of bronchiolitis obliterans syndrome (BOS). BOS is a result of chronic immunological processes inducing inflammation in and scarring of the smallest airways ('bronchioles'). Bronchoscopic biopsy samples are almost never contributive to the diagnosis. Both emphysema and BOS have common pathophysiological pathways. In both conditions one assumes that vanishing airways are at the beginning of the ultrastructural changes. In both diseases, changes at the bronchiolar level are driven by inflammation : immunological due to rejection/allo-immunity, as a result of toxic exposure (cigarette smoking, biomass combustion), as a result of auto-immunity or due to the inflammatory influence as a result of recurrent infection. The injury afflicted by inflammation results the development of an abnormal cytokine response profile inducing epithelial-mesenchymal transition and fibroproliferation. Probe-based confocal laser endomicroscopy (pCLE) is a novel endoscopic imaging technique that is capable of three dimensional and in vivo imaging during flexible endoscopy of the respiratory tract. The technique uses a thin, semi-flexible probe that can be advanced through the human airways by inserting it in the working channel of a bronchoscope. The scope of our research project is to standardize the implementation of pCLE during flexible bronchoscopy, to assess consistency and reliability of quantitative data and to assess changes at the level of the pulmonary acinus in small airway disease. For the latter purpose, the technique will be used in subjects with COPD and BOS. Consequently, we will try to correlate pCLE data with data from clinical examinations such as lung function and computerized tomography of the chest.status: publishe