Increased vascular density is a persistent feature of airway remodeling in a sheep model of chronic asthma

ABSTRACTBackground: Increases in blood vessel density and vascular area are now recognized as important features of remodeled airways in asthma. However, the time sequence for these vascular changes and whether they resolve in the absence of continued antigenic exposure is not well elucidated. The aim of the present study was to correlate progressive changes in airway vascularity with changes in functional airway responses in sheep chronically challenged with house dust mite (HDM) allergen, and to examine the resolution of vascular remodeling following allergen withdrawal. Methods: Progressive changes in vascular indices were examined in four spatially separate lung segments that received weekly challenges with HDM allergen for 0, 8, 16, or 24 weeks. Reversibility of these changes was assessed in a separate experiment in which two lung segments received 24 weeks of HDM challenges and either no rest or 12 weeks rest. Lung tissue was collected from each segment 7 days following the final challenge and vascu...