Angiogenesis is considered a crucial step in the pathogenesis of RA, and Chi3l1 can induce interleukin-18 (IL-18) expression in osteoblasts and promote angiogenesis in endothelial progenitor cells (EPCs) by inhibiting miR-590-3p via the focal adhesion kinase (FAK)/PI3K/Akt cascade (Figure 2) [249]. Here, IL18 is linked to rheumatoid arthritis.