Allergen exposure of mouse airways evokes remodeling of both bronchi and large pulmonary vessels

Remodeling of airway structures is a well-documented feature of allergic airway inflammation. To investigate whether bronchial remodeling is associated with remodeling of adjacent pulmonary vessels, sensitized mice were subjected to repeated ovalbumin inhalations, and bronchi and pulmonary vessels were subjected to histologic analysis. Allergen challenges induced peribronchial as well as perivascular eosinophilia. Remodeling of systemic airway microcirculation, as studied in tracheal whole-mount preparations, revealed an allergen-induced increase in both the diameter and length of the airway microvessels. Immunostaining for alpha-smooth muscle actin disclosed an increase in smooth muscle mass in both bronchi and large pulmonary vessels. Both bronchi and pulmonary vessels also displayed increased expression of procollagen I and procollagen III. Staining for proliferating cell nuclear antigen revealed increased proliferation of bronchial epithelial and smooth muscle cells as well as pulmonary vascular endothelial and smooth muscle cells. We conclude that central features of remodeling that take place in allergen-exposed airways are present also in the pulmonary vessels. The significance of this finding with respect to occurrence in disease, pathophysiologic importance, and involved mechanisms warrants further investigation.