IL-37 (IL-1F7, IL-1H4) is an IL-1 family member that is expressed only in certain types of human organs and cells such as heart, thymus, testis, kidney, mononuclear cells (PBMCs) and dendritic cells. IL-37 is an inhibitor of innate immunity with anti-inflammatory properties. It binds to the interleukin-18 receptor (IL-18R) and its co-receptor SIGIRR. IL-37 is secreted as a full-length and as a processed form starting from amino acid Val46. It plays an important role as a link between innate and adaptive immunity and acts as an inhibitor of autoimmune diseases and tumor growth. IL-37 also inhibited Lipopolysaccharide (LPS)-induced immunological reaction and LPS-induced osteoclast formation and bone resorption.