Airway remodeling: A comparison between fatal and nonfatal asthma

Background: Airway remodeling has been recently one of the main goals in asthma research because it has been implicated to influence airway behavior and evolution of asthma; hence, important in long-term followup of asthmatic patients. Methods: Airways of fatal asthma (n=3), non-fatal asthma (n=3) and control cases (n=4) were studied using morphometry and immunohistochemical and H&E staining. Results: The basement membrane was thicker in the cartilaginous and membranous airways of fatal and non-fatal asthma groups compared to the control group (p<0.05). Smooth muscle shortening was greater in airways of fatal asthma cases while submucosal gland area and mucus plug occupying ratio were greater in fatal asthma large airways compared to the two other groups (p<0.01). Increased intact and degranulated mast cells were observed in smooth muscle and in submucosal gland of fatal asthma airways (p<0.01) and were associated with greater degree of smooth muscle shortening and larger submucosal gland area, respectively. Eosinophil and EG2+ cell infiltrations were greatest in lamina propria of airways of fatal asthma than in nonfatal and control cases (p<0.01), but were not associated with any airway structural change. Conclusion: Increased infiltration of eosinophils in the lamina propria and mast cells in smooth muscle and submucosal glands may have a role in airway remodeling of fatal asthma airways but needs further investigation. Moreover, mast cells in cartilaginous airways may participate in the regulation of smooth muscle tone and mucous gland secretion and hyperplasia.