The majority of studies suggest prevalent anti-osteoclastogenic and osteoanabolic functions of IL-33, but the reduced expression of OPG by osteoblasts and the induced production of the osteoclastogenic cytokine IL-31 (97), have also been reported, suggesting that in particular inflammatory conditions, including arthritis and Pso, IL-33 can induce bone resorption. This evidence concerns the gene IL33 and arthritic joint disease.