Elastic-Collagen Profile in Emphysematous Airspaces from Different Chronic Fibrosing Lung Disorders

Abstract

Background: Parenchyma elastic and collagen components of chronic fibrosing lung disorders has been exhaustively investigated, but little attention has been aimed at the emphysematous airspaces present in bullous disease, smoking-related interstitial disease and usual interstitial pneumonia. The aim of this study was to evaluate whether elastic deposition accompanies collagen deposition in the repairing process of emphysematous airspaces in chronic fibrosing lung injuries. Design: The elastic and collagen fibers distribution were evaluated in emphysematous airspaces of bullous type I and II disease, smoking-related interstitial fibrosis and of usual interstitial pneumonia (UIP). Lung specimens obtained by surgical lung biopsy or by bullectomy divided the patients into four groups: 1) type I bullous disease (SPT-I; n=7); 2) type II bullous disease (SPT-II; n=12); 3) smoking-related interstitial pneumonia (SRIP; n=5) and 4) usual interstitial pneumonia/idiopathic pulmonary fibrosis (UIP/IPF; n=5). Collagen and elastic fibers were identified respectively by Picrosirius-polarization and Weigert's resorcin-fucsin staining and quantified by image analysis.The results were expressed in percentual area. Results: The proportion of collagen fibers was two times higher when compared with the elastic component in the four groups. In addition, a lower percentage of elastic and collagen fibers were observed in SRIP when compared with UIP/IPF, SPT-I and SPT-II. Conclusions: A smaller amount of elastic and collagen fibers accompanies the remodeling of the emphysematous airspaces in smoking-related interstitial pneumonia when compared to the other fibrosing diseases, suggesting a different remodeling spectrum in chronic fibrosing lung diseases.