IL1B and rheumatoid arthritis: For example, the IL‐1 gene cluster was related to increase the risk of ankylosing spondylitis (Maksymowych et al., 2006); inhibiting the IL‐1 could reduce cartilage damage in rheumatoid arthritis (Strand & Kavanaugh, 2004); and the recently discovered IL‐33 as an IL‐1 cytokine family member has been proved to be specifically released from osteonecrotic bones (Saidi et al., 2011).