Fig. 1.

Expression of interleukin (IL)-38 is upregulated in osteoarthritis (OA). a) Representative images of cartilage damage in OA mice assessed by safranin O-fast green staining (n = 10; 200×); b) Osteoarthritis Research Society International (OARSI) scores of cartilage damage in OA mice, *p < 0.05 versus sham-operated mice (n = 10). c) IL-38 level in synovial fluid from OA mice detected by enzyme-linked immunosorbent assay (ELISA). *p < 0.05 versus sham-operated mice at different timepoints (n = 5). d) IL-38 level in the supernatant of chondrocytes after IL-1β treatment detected by ELISA. *p < 0.05 versus control chondrocytes. e) Messenger RNA (mRNA) and protein expressions of IL-38 in cartilage tissues from OA mice (n = 10). *p < 0.05 versus sham-operated mice (n = 10). f) and g) mRNA (f) and protein (g) expression of IL-38 in chondrocytes after IL-1β treatment measured by quantitative reverse transcription polymerase chain reaction and western blot analysis. h) The expression of IL-38 in chondrocytes determined via immunofluorescence (400×). *p < 0.05 versus control chondrocytes. The measurement data were expressed as mean (standard deviation). Comparison between two groups was conducted by independent-samples t-test. The cell experiment was repeated three times independently. Ctr, control.