The Expanding Role of ILC2s in Allergic Airways Disease

Group 2 innate lymphoid cells (ILC2s) play a pivotal role in the initiation and propagation of allergic airways disease. These cells, first discovered 15 years ago, respond to a range of stimuli in a non-antigen-dependent manner. ILC2s produce copious amounts of cytokines including IL-5 and IL-13, which are critical in the pathogenesis of allergic asthma. While allergic airways diseases have long been considered T-helper 2 cell-driven diseases, ILC2s are capable of inducing allergic-type pathologies in mice even in the absence of the adaptive immune system. The role of ILC2s in driving the pathology of allergic airways disease remains an expanding field of knowledge that may unlock novel therapeutic approaches in the management of asthma, a disease that affects up to 300 million people worldwide. In this review, we survey current knowledge of ILC2 immunobiology and present an overview of ILC2 phenotyping, concurrent with insights into ILC2 plasticity, and an exploration of the roles of costimulatory molecules, neuroendocrine signals, and diet-derived nutrients in modulating ILC2 activity.