Groups of mice were subjected to ligature-induced periodontitis (LIP) for 5 days by ligating a maxillary second molar and leaving the contralateral tooth unligated to serve as baseline control. One day prior to LIP (day −1), the mice were microinjected, or not, with anti-IL-6Rα mAb or isotype control. (A) Bone loss determination relative to corresponding unligated baseline. (B) Relative gingival mRNA expression of indicated cytokines determined by quantitative real-time PCR. Data are means ± SD (n = 7 mice per group). *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001 between indicated groups (One-way ANOVA with Tukey’s multiple comparison test). IC, isotype control, NS, not significant.