Fig 2: HMGB1 regulates the production of MMP13, ADAMTS5, IL-1ß and IL-6 from TMJOA synovial fibroblasts. A,C,E,G) A dose-dependent augmentation of MMP13, ADAMTS5, IL-1ß and IL-6 in synovial fibroblasts was induced by HMGB1 for 24 h. B,D,F,H) A time-dependent increase of MMP13, ADAMTS5, IL-1ß and IL-6 in these cells was induced by 100 ng/mL of HMGB1. Western blotting assays were used to assay the relative expression levels; ß-actin served as control; data are shown as the means with 95% CI and are analyzed by Mann-Whitney U test, n=6, *p< 0.05, **p<0.01, ***p<0.001.

Fig 3: Inhibition of HMGB1 decreases the expression of pro-inflammatory cytokines and catabolic mediators in rat synovium of CFA induced TMJOA. A) The schematic chart for the timeline of treating rats. B) The expression of ADAMTS5, MMP13, IL-1β, IL-6 and negative controls was detected by immunohistochemistry in the synovium of CFA groups, CFA with anti-HMGB1 antibody treatment groups at day 21, or in the control synovium; scale bar: 100 μm. C) Quantitative analysis of ADAMTS5, MMP13, IL-1β and IL- 6 in the synovium of rats; data are shown as the means with 95% CI and analyzed by one-way analysis of variance (ANOVA), n=5, *p<0.05, **p<0.01, ***p<0.001.

Fig 4: Inhibition of HMGB1 suppresses the NF-?B signaling pathway in vivo. Expression of phospho-p65 in the synovium (A) and cartilage (B) of CFA groups, CFA with anti-HMGB1 antibody treatment groups at day 21 were detected by IF staining, or in the control groups; data are shown as the means with 95% CI and analyzed by one-way analysis of variance (ANOVA), n=5, *p<0.05, **p<0.01, ***p<0.001; scale bar: 100 µm. C) Schematic diagram of inhibition of HMGB1 suppresses inflammation and catabolism in temporomandibular joint osteoarthritis via NF-?B signaling pathway.

Fig 5: Inhibition of HMGB1 alleviates the damage of cartilage and subchondral bone in CFA induced TMJOA. A) H&E, Safranin O and Masson trichrome staining of rat models at day 21; scale bar: 100 µm. B-D) Analysis of the condylar cartilage thickness, the Safranin O positive areas and unmineralized bone areas; data are shown as the means with 95% CI and analyzed by one-way analysis of variance (ANOVA), n=5, *p<0.05, **p<0.01, ***p<0.001.