Fig. 2

T_H17 cells protect against the invasion of oral microbiota and induce bone damage. a Number of IL-17A⁺CD4⁺TCRβ⁺ cells in the periodontal tissues at various time points after the ligature placement (n = 3). Representative data of two independent experiments is presented. b, c Effects of an antibiotic cocktail (Abx; ampicillin 1 mg ml⁻¹, streptomycin 5 mg ml⁻¹, and colistin 1 mg ml⁻¹ in drinking water) on the accumulation of T_H17 cells. Mice were treated with Abx from 1 week before the ligature placement. The frequency (b) and number (c) of IL-17A⁺CD4⁺TCRβ⁺ cells in the periodontal tissues were analyzed 7 days after the ligature placement (n = 3). PD: periodontitis. d Micro-CT analysis of periodontitis-induced bone loss in the wild-type (n = 4) or Il17a^−/−Il17f^−/− mice (n = 6), pooled from three independent experiments. The upper red dotted line indicates the cementoenamel junction and the lower red dotted line indicates the alveolar bone crest in the left panel. e Osteoclast number in the maxilla of the wild-type (n = 5) or Il17a^−/−Il17f^−/− mice (n = 6), pooled from two independent experiments. f Total bacterial load in ligatures collected from wild-type (n = 4) or Il17a^−/−Il17f^−/− mice (n = 3). Representative data of two independent experiments is presented. g Oral bacterial composition (major phylum; class) of the wild-type (n = 6) or Il17a^−/−Il17f^–/–mice (n = 4). h Abundance of γ-proteobacteria in the oral bacteria of the wild-type (n = 6) or Il17a^−/−Il17f^−/−mice (n = 4). i Differences in the bacterial composition between the wild-type (n = 6) and Il17a^−/−Il17f^−/−mice (n = 4). Principal coordinate analysis (PCoA) and permutational ANOVA (PERMANOVA) comparisons of the weighted UniFrac distances are shown. PCo1: principal coordinate 1; PCo2: principal coordinate 2. The data were pooled from two independent experiments (g–i). All data are shown as the mean ± s.e.m. Statistical analyses were performed using ANOVA with Tukey’s multiple-comparison test (c), Student’s t-test (d–f and h) or PERMANOVA of the weighted UniFrac distances (i). *P < 0.05; ***P < 0.005