Implications of IL-13Rα2 in atopic skin inflammation

Atopic dermatitis (AD) is a common eczematous skin disorder characterized by skin inflammation, barrier disruption, chronic pruritus and marked scratching. Th2 cytokines, especially IL-13, play a pathogenic role in AD. IL-13 signals via a heterodimeric receptor composed of IL-4Rα and IL-13 Rα1. A second receptor, IL-13 Rα2, binds to IL-13 with high affinity, but it works as a decoy receptor. IL-13 Rα2 is overexpressed in the lesional skin of AD. Notably, mechanical scratching, as well as IL-13 itself, also upregulates IL-13 Rα2 expression. The scratch-induced IL-13 Rα2 upregulation may attenuate the IL-13-mediated epidermal barrier dysfunction and dermal fibrosis. Recent studies stress an importance of another IL-13 Rα2 ligand, chitinase 3-like 1 or YKL-40 in Th2 differentiation. However, the implications of increased IL-13 Rα2 levels remain elusive in AD. In this review, we summarize the recent topics on IL-13 Rα2 in atopic skin inflammation.