Fig. 5

Stimulation of the STING in mouse knee joints exacerbates post-traumatic OA cartilage destruction and OA-associated mechanical sensitivity. A Wild-type (WT) mice were IA injected with 20 μg of cGAMP or PBS once weekly for 3 weeks, and sacrificed at 3 weeks or 8 weeks after the first IA injection. Presented are representative safranin-O staining images of joint sections (A, n = 5 mice/10 knees per group). B and C Sham- or DMM-operated WT mice were IA injected once a week for 3 weeks with the indicated concentrations of cGAMP (μg) or PBS starting at 10 days after DMM surgery. Presented are representative safranin-O staining images (B) and OARSI grade, osteophyte maturity, and SBP thickness (C). D von Frey assay at the indicated weeks post-DMM surgery in mice IA injected with cGAMP or vehicle (PBS) (n = 15 mice per group). Values in C and D are presented as median ± interquartile range (IQR) for OARSI grade and osteophyte maturity, mean ± s.e.m for paw threshold, and mean ± 95% CI for SBP thickness. Significance was evaluated by Kruskal–Wallis with post-hoc Bonferroni test for OARSI grade and osteophyte maturity, Student t-test for paw threshold, and one-way ANOVA with post-hoc Bonferroni test for SBP thickness. Scale bars: 50 µm