Elastosis and fragmentation of fibers of the elastic system in fatal asthma

Fibers of the elastic system (FES) are important in regulating airway patency and lung elastic recoil. Their possible role in modulating bronchoconstriction is not fully understood. Chronic inflammation and mechanical stretching present in asthma could lead to conformational alterations in the FES, participating in the mechanism of airway remodeling observed in this disease. In airway mucosa, two layers of FES are discernible: one superficial network, attached to the basement membrane, and a deeper network, lying close to the airway smooth muscle. Using image analysis and conventional morphometry, we analyzed airway content of FES in central and peripheral airways in 31 cases of fatal asthma and in 10 control lungs. Slides were stained using the oxidized resorcin-fuchsin method. Optical analysis revealed fragmentation of the FES in the superficial network of central asthmatic airways. Morphometry showed the presence of elastosis in central asthmatic airways when the entire thickness of the mucosa was considered. In the superficial network elastic fiber content was significantly decreased. These results indicate that FES participate in airway remodeling in asthma. We also suggest that disrupture of fiber attachments at the basement membrane in the superficial layer could impair the mechanism of airway recoil in asthmatic patients.