IL1B and osteoarthritis: In an effort to counter this degeneration and preserve joint morphology, the researchers selectively deleted the cytokine interleukin 1 beta (IL‐1B) and the enzyme matrix metalloproteinase 13 (MMP13) using the same recombinant system, given that IL‐1B is upregulated in osteoarthritis and MMP13 is a dominant collagenase expressed in osteoarthritic cartilage.