Fig. 1.

Targeting IL-22 signaling protects against experimental osteoarthritis. IL-22 concentration (pg/mL) in a SF and b serum of non-OA and OA patients (n = 25). c IL-22 mRNA, d IL-22R mRNA and e IL-22 and IL-22R protein expression in isolated human chondrocytes from non-OA and OA patients (n = 18). f IL-22 mRNA, g IL-22R mRNA and h IL-22 and IL-22R protein expression in isolated FLS from non-OA and OA patients (n = 18). i, j OARSI scoring of cartilage and k von Frey pain assessment of sham- or DMM-operated IL-22R^fl/fl control mice and IL-22R^{Acan Cre-ERT2} mice (12 weeks post surgery end timepoint) (n = 20). l, m OARSI scoring of cartilage and n von Frey pain assessment from sham- or DMM-operated WT mice treated i.a. with either IgG1 (control; 50 µg per mouse; 3 times per week for 12 weeks post surgery) or αIL-22R (50 µg per mouse; 3 times per week for 12 weeks post surgery) (n = 20). All RT-qPCR gene expression levels were normalized to the endogenous level of 18S in the respective groups. Data are expressed as the mean ± SEM with two-tailed t-test or two-way analysis of variance followed by the Tukey-Kramer test or repeated measures 2-way ANOVA with Bonferroni’s post hoc tests. n indicates the number of human specimens or mice per group. NS nonsignificant. ***p < 0.001 or ****p < 0.0001 is represented in all figures