Effects of preoperative administration of high-mobility group box 1 protein (HMGB1) neutralizing monoclonal antibody on the HMGB1 and interleukin (IL)-6 serum concentration at 1 and 24 h after tibia fracture (Arm C). The dotted lines represent the average values for respectively for HMGB1 and IL-6 concentration of six control mice without any treatment or surgery (n = 6). (A) Levels of HMGB1 serum concentration 1 and 24 h after surgery. After log transformation of the raw data, we observed with two-way ANOVA significant time and treatment effects (P = 0.002 for the time effect; P = 0.005 for the treatment effect, and P = 0.010 for interaction between time and treatment) and a significant difference between the two groups at 1 h (22.00 ± 16.54 vs. 5.29 ± 4.13 surgical control vs. anti-HMGB1 + surgery; P = 0.040 with two-way ANOVA with Bonferroni’s post hoc analysis). (B) Levels of IL-6 serum concentration 1 and 24 h after surgery. After log transformation of the raw data, we observed with two-way ANOVA significant time and treatment effects (P = 0.015 for the time effect; P < 0.001 for the treatment effect; and P = 0.015 for interaction between time and treatment) and a significant difference between the two groups at 1 h (24.24 ± 12.87 vs. 4.90 ± 4.47 surgical control vs. anti-HMGB1 + surgery; P = 0.006 with two-way ANOVA with Bonferroni’s post hoc analysis). Anti-HMGB1 = neutralizing HMGB1 monoclonal antibody.