LOWER AIRWAYS REMODELING IN NONASTHMATIC SUBJECTS WITH ALLERGIC RHINITIS

We analyzed by immunohistochemistry the distribution of types I, II, I II, IV, V, and VII collagens, laminin, and fibronectin in the bronchia l biopsy specimens of nonasthmatic subjects with seasonal allergic rhi nitis (n = 8) and compared these results with those found in mild stab le allergic asthmatics (n = 6) and normal controls (n = 5). The conten t of type I and III collagens was increased in rhinitic subjects compa red with controls. These collagens were focally deposited in the retic ular basement membrane area. Three subjects with allergic rhinitis had no fibronectin deposition in their basement membrane, as in controls, whereas the other five had a focal fibronectin deposition. In asthmat ic patients, type I and III collagens and fibronectin were more abunda nt and more uniformly distributed underneath the basement membrane tha n they were in rhinitic subjects. Expression of type II, IV, V, and VI I collagens and laminin were similar in the three groups. Electron mic roscopic and immunohistochemical analyses of bronchial mucosa showed a network of myofibroblasts beneath the epithelium in rhinitis as in as thma subjects. These data show that the irregularly distributed subepi thelial fibrosis observed in subjects with allergic rhinitis results f rom the deposition of type I and III collagens and fibronectin, probab ly produced by bronchial myofibroblasts. These results suggest the pre sence of an active structural remodeling in the lower airways of aller gic rhinitic subjects that is similar in nature to that seen in asthma , although less marked.