Andersson CK, et al. - This inquiry was set up to find out mast cell (MC) phenotypes in correlation to deposition of specific collagen subtypes in patients with controlled and uncontrolled asthma as well as to healthy controls. In patients with uncontrolled atopic asthma, an altered pro-fibrotic MC_TC phenotype was noted in the alveolar parenchyma that was found to be related to alveolar collagen VI. Histopathologically, distal lung mast cell and matrix changes were supported as asthma features and these may be of particular clinical relevance in patients who have remaining symptoms despite conventional inhaler therapy.