The interleukin-13 paradox in asthma: effective biology, ineffective biologicals

Interleukin-13 (IL-13) is a pleiotropic cytokine produced by type-2 helper T-cells (Th2), mast cells and basophils, and is thought to be involved in many of the features of asthma. IL-13 induces many biological responses relevant to asthma, such as B-cell immunoglobulin E production, generation of eosinophil chemoattractants, maturation of mucus-secreting goblet cells, production of extracellular matrix proteins and myofibroblast differentiation, and enhanced contractility of airway smooth muscle cells in response to cholinergic agonists. These cytokines activate the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signalling cascades, which may contribute to allergic responses. IL-13 is involved in almost all aspects of asthma pathobiology, yet, anti-IL-13 mAb clinical trials, including the prednisone-sparing TROPOS study published in this issue of the ERJ, have been ineffective http://ow.ly/ZMnd30n27VN