Figure 1.

FRNK deficiency promotes lung fibrosis in response to bleomycin in mice. A: FRNK knockout (FRNK^−/−) and WT littermate mice were intratracheally instilled with saline (Sal) or 1 U/kg bleomycin (Bleo). Lungs were harvested at day 21 and stained with H&E. Original magnification, ×200. B: The severity of fibrosis was examined morphometrically and represented by lesional density (% of lesional area over total parenchymal area, excluding airway and vessel). C: Masson’s trichrome staining for collagen deposition. Original magnification, ×400. D: The trichrome-positive area was quantified morphometrically. E: Hydroxyproline level was measured from non-challenged (None) or Sal- or Bleo-instilled mice, and represented as %hydroxyproline normalized to that in non-challenged WT mice. F: Lungs were harvested at day 14 after bleomycin instillation. Whole lung lysates underwent Western blot analysis for procollagen 1α1 (Pro-Col) or fibronectin (FN). GAPDH was used as a loading control. G and H: Densitometric analysis of Pro-Col and FN expression. I: Stepwise pressure-volume (PV) loops captured the mechanical properties [quasi-static compliance (CST)] of the lung at day 21 after challenge. Lung compliance (CST-PV) was represented as mL/cm H₂O. Data were represented as means ± SE (n = 8 animals per group). ∗P < 0.01.