Article Text

IL-33: a Janus cytokine
  1. F Y Liew1,2
  1. 1Institute of Infection, Immunity and Inflammation, University of Glasgow, UK
  2. 2Center of Excellence in Genomic Medicine Research, King Abdulaziz University, Jeddah, Saudi Arabia
  1. Correspondence to Professor Foo Y Liew, Institute of Infection, Immunity and Inflammation, University of Glasgow, 120, University Place, Glasgow G12 8TA, UK; foo.liew{at}


Interleukin (IL) 33, a member of the IL-1 family, is the ligand of ST2 that is expressed mainly on activated Th2 cells and mast cells. IL-33 can skew a predominantly Th1 cell population to a mainly Th2 cells phenotype in vivo. IL-33 messenger RNA is expressed early during infection of the intestinal-dwelling nematode Trichuris muris in mice. IL-33 treatment enhances resistance to Trichuris infection. IL-33 also effectively attenuates sepsis by mobilising the innate cells, neutrophils, to the site of infection, helping to clear the pathogens. Thus, IL-33 may be evolutionally preserved for the host defence against infections. IL-33 can reduce an ongoing atherosclerosis in ApoE−/− mice and attenuate adipocytes mainly by inducing the production of type II cytokines. In contrast, IL-33 can also exacerbate allergy and the inflammation in collagen-induced or serum-induced arthritis. Hence, IL-33 is a double-edged sword, and targeting IL-33 should be approached with caution.

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  • Competing interests None.

  • Provenance and peer review Commissioned; externally peer reviewed.

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