Figure 1. Cellular targets of IL-25, IL-33, and TSLP in allergic diseases. Genetic defects and environmental stimuli stimulate epithelial cells to secret alarmins. These cytokines exert pro-inflammatory effects by acting on a wide range of cell populations. Specifically, they can 1) enhance the survival, recruitment, and degranulation of granulocytes such as eosinophils and mast cells; 2) immediately cause ILC2s to secrete IL-5 and IL-13; 3) act directly on TH2 cells since they induce their terminal differentiation in peripheral inflamed tissues; 4) convert ST2-expressing Tregs into TH2-like Tregs that produce IL-5 and IL-13; and 5) act on somatosensory neurons and keratinocytes, thereby promoting itching and disrupting the skin barrier, respectively.
