Thymic stromal lymphopoietin

Thymic stromal lymphopoietin (TSLP) is an epithelial cell‐derived cytokine expressed in skin, gut, lungs, and thymus. TSLP signals via a TSLP receptor (TSLPR), a heterodimer of the IL‐7 receptor α chain and the TSLPR chain. The TSLPR chain is closely related to the common receptor γ chain that is expressed on a wide range of cell types in the adaptive and innate immune system. TSLP exerts a profound influence on the polarization of dendritic cells to drive T helper (Th) 2 cytokine production. TSLP also directly promotes T‐cell proliferation in response to T‐cell receptor activation and Th2 cytokine production and supports B‐cell expansion and differentiation. TSLP further amplifies Th2 cytokine production by mast cells and natural killer T cells. These properties confer on TSLP a critical role in driving Th2‐mediated inflammation. This role is supported by the finding that TSLP expression is upregulated in keratinocytes of atopic dermatitis skin lesions and in bronchial epithelial cells in asthma.