Fig. 7. Cd/CB-induced Vim citrullination and lung fibrosis are dependent on PAD2 expression, and respiratory mechanics analysis demonstrates decreased disease susceptibility in PAD2^−/− mice.

(A) Immunoblot analysis in mice lung macrophages from WT (Sal, n = 4; Cd + CB, n = 6) and PAD2^−/− mice (Sal, n = 5; Cd + CB, n = 5) treated with Sal or CdCl₂ (0.16 mg/kg) plus CB (5.0 mg/kg). Arrow represents specific band. (B) Quantification of PAD2 expression from (A) (n = 3). Cit-Vim amounts by ELISA in (C) plasma and (D) BALF at day 14. (E) Representative lung histology with collagen-1 staining at day 14. (F) DAB staining density from (E) was quantified. Scale bars, 100 μm. (G) Hydroxyproline content at day 14. Respiratory mechanics analysis was performed in paralyzed and mechanically ventilated mice 14 days after Sal or CdCl₂ plus CB administration. The parameters (H) Cst, (I) K, and (J) A were assessed using the baseline values. (K) Rrs, (L) Rn, (M) G, and (N) H were evaluated using both baseline values (top) and average values from 12 measurements at different concentrations of methacholine (bottom). Each dot represents individual mouse. *P < 0.05, **P < 0.01, and ***P < 0.001 using one-way ANOVA followed by Tukey’s post hoc analysis.