MUC5AC and pemphigus foliaceus: In contrast, IL6, which was recently implicated in airway epithelial dysfunction in fibrotic lung diseases26, was broadly expressed in AT2, Mesothelial, MUC5AC+ High, MUC5B+ and Goblet epithelial cell types (Supplementary Fig. 4 and Supplementary Data 1) but seen rarely in transitional cells in both control and PF lungs.