Fig. 2.

Exogenous overexpression of interleukin (IL)-38 attenuates inflammatory response of osteoarthritis (OA) mice. a) Messenger RNA (mRNA) expression of IL-38 in knee joint cartilage tissues from OA mice and sham-operated mice in response to lentivirus vector (LV)-IL-38 or LV-negative control (NC), as determined by quantitative reverse transcription polymerase chain reaction (RT-qPCR). *p < 0.05 versus sham-operated mice injected with LV-NC; #p < 0.05 versus OA mice injected with LV-NC. b) IL-38 protein level in the knee joint cartilage tissues (left) and synovial fluid (right) from OA mice and sham-operated mice in response to LV-IL-38 or LV-NC as measured using western blot analysis and enzyme-linked immunosorbent assay (ELISA). *p < 0.05 versus sham-operated mice injected with LV-NC; #p < 0.05 versus OA mice injected with LV-NC. c) Levels of inflammation-related factors (IL-6, IL-8, IL-17, IL-22, tumour necrosis factor (TNF)-α, interferon (IFN)-γ, and cartilage oligomeric matrix protein (COMP)) in synovial fluid from OA mice and sham-operated mice in response to LV-IL-38 or LV-NC, tested using ELISA. d) The Osteoarthritis Research Society International (OARSI) score of cartilage damage in OA mice and sham-operated mice treated with LV-IL-38 or LV-NC identified by safranin O-fast green staining. e) Chondrocyte apoptosis in OA mice and sham-operated mice treated with LV-IL-38 or LV-NC detected using Terminal deoxynucleotidyl transferase dUTP Nick-End Labeling (TUNEL) assay. In panels c) to f), *p < 0.05 versus OA mice with injection of LV-NC. The measurement data were expressed as mean (standard deviation). The cell experiment was repeated three times independently. Comparison between two groups was conducted by independent-samples t-test; n = 10.