Figure 4.

Lung epithelial–specific deletion of α3 laminin worsens pulmonary fibrosis induced by active transforming growth factor-β (TGF-β) (A–C) Mice with the indicated genotype were treated with bleomycin (0.01 IU/mouse) and, 5 days later, the levels of mRNA encoding the TGF-β target gene, connective tissue growth factor (CTGF), plasminogen activator inhibitor-1 (Pai-1), and TGF-β (which induces its own transcription) were measured in lung homogenates (n = 5 animals per group). (D) Mice with the indicated genotype were treated intratracheally with an adenovirus encoding no transgene (Ad-Null) or an adenovirus encoding an active form of TGF-β (Ad–TGF-β) both at 1 × 10⁸ plaque-forming units [pfu]/animal, and the lungs of the mice were harvested 28 days later. Trichrome-stained lung sections of the TGF-β–treated mice were imaged at 100× using a TissueGnostics system. Left panels are montage images; right panels are higher-magnification views of the areas indicated by the squares. (E) Fibrosis severity was quantified using Ashcroft scores (n = 4 animals per group). (F) Total lung collagen was measured in whole-lung homogenates by picrosirius red collagen precipitation (n = 5–10 mice in the (Ad-Null) control groups and n = 12 and 10 mice in the TGF-β–treated groups). (G) Lung compliance was measured using the FlexiVent system before harvest (n = 4 animals per group). All animals were 8–12 weeks of age at the time of bleomycin administration or adenoviral infection. When present, significant differences between groups are indicated in the figures. Error bars indicate SEM.