Fig. 3

Expression and localization of FGF1 and FGF-receptors FGFR1, FGFR2, FGFR3 and FGFR4 in hyperplastic, overlying alveolar epithelium, fibroblastic foci and basal cell sheets in idiopathic pulmonary fibrosis (IPF) lungs. a. Representative immunohistochemistry for FGF1, FGFR1, FGFR2, FGFR3, and prosurfactant protein C (pro-SP-C) in serial sections of IPF lung tissue. Alveolar epithelial type-II cells (AECII, indicated by arrows) of IPF lungs express FGF1 (a1,2), FGFR2 (a4,5), FGFR3 (a6,7), and FGFR4 (a8,9), but not FGFR1 (a3,4). b. Representative immunohistochemistry for Cytokeratin-5 (KRT5) (b1,2), Fascin (b3,4), FGF1 (b5,6) α-SMA (b7,8), FGFR1 (b9,10), and FGFR2 (b11,12) in serial sections of IPF lung tissue. In IPF, immunostaining for FGF1, FGFR1 and FGFR2 was observed in myofibroblasts of fibroblast foci [FF] (indicated by arrowheads and α-SMA-staining) as well as in overlying hyperplastic bronchiolar basal cells (indicated by asterisks and KRT5-staining), and colocalized with expression of the migratory marker Fascin (2). Representative immunohistochemistry for α-SMA (b13), FGFR3 (b14) and FGFR4 (b15) and FGF1 (b16) in serial sections of IPF lung tissue. In general, α-SMA-positive myofibroblasts of FF (indicated by arrowheads) express FGF1, FGFR3 and FGFR4. Of note, FGFR3 expression appeared predominantly nuclear in AECII as well as myofibroblastic cells. Scale bars: a1-9 (100 μm); b1,3,5,7,9,11 (250 μm), b2,4,6,8,10,12 (100 μm), b13-16 (100 μm)