Overall, the IL-38/IL-36R axis performs its anti-inflammatory function by suppressing proinflammatory cytokines from Mφs, PBMCs or FLSs, and RA-SFs induced by IL-1β significantly induce inflammation, indicating that IL-38/IL-1R1 may be involved in this process. Here, IL1RL2 is linked to rheumatoid arthritis.