Uncovering the Complexities of Interleukin-33 Signalling in COPD

Interleukin-33 (IL-33) is an alarmin cytokine released by airway epithelial cells in response to damage or infection (1, 2). The IL-33 receptor, known as ST2, is found as a transmembrane receptor, and can also be secreted, where it is believed to function as a decoy molecule, reducing IL-33 function (1). Studies using animal models of COPD and asthma have shown that IL-33 release causes activation of several immune cell types including Type 2 innate lymphoid cells (ILC2s), T-helper 2 cells, eosinophils and macrophages, driving a Type 2 immune response with increased production of Type 2 cytokines IL-4, IL-5 and IL-13 (3, 4).