Inhibition of citrullination protects from periodontal bone loss. (A and B) Bone loss measurements with or without LIP (6 d) in (A) WT and Padi4 KO (n = 5–6) mice or (B) mice treated with CI-amidine or vehicle (n = 10). (C) Flow cytometry analysis of mouse oral gingival tissues after LIP (18 h) in WT and Padi4 KO mice (n = 4). Graph indicating absolute number of CD45+ or neutrophils (CD45+CD11b+CD11clow/medLy6G+) per standardized tissue block. (D–H) Immunofluorescence for citH3, Ly6G, MPO in gingival tissues from Padi4 KO and WT mice, with or without LIP (n = 5, 18 h). (D and G) Representative images and conditions are indicated. Scale bars are 50 µm. (E, F, and H) Quantification, mean fluorescence intensity for citH3, Ly6G, and MPO staining (n = 5). Data are representative of three (A, C, E, F, and H) or four (B) independent experiments. Graphs show the mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. One-way ANOVA with Tukey’s multiple comparison test (A, B, E, F, and H), unpaired t test (C).