Fig. 3

Metformin protected against interleukin-1β (IL-1β)-driven catabolism in chondrocytes. Mice articular chondrocytes (n = 3) were cultured with IL-1β and metformin (1, 10, and 20 mM) for 24 h, and the transcription of mmp13 (a) was determined via qRT-PCR in mice articular chondrocytes treated with IL-1β and metformin (1, 10, and 20 mM). Protein levels of MMP13 (b) and type II collagen (d) were detected by western blot. The quantitation of protein expression of MMP13 (c) and type II collagen (e) was done by densitometry analysis of the protein bands. Values were normalized against tubulin or GAPDH. Chondrocyte viability was assessed with cell counting kit-8 (CCK8) assay (f). Data were expressed as the mean ± 95% confidence intervals. *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001; Statistical significance was calculated using one-way ANOVA with Tukey’s post hoc test. MMP13, matrix metalloproteinase 13; OD, optical density; GAPDH, glyceraldehyde-phosphate dehydrogenase