P2X7 receptor in skin biology and diseases

Figure 1 Expression and function of the P2X7 receptor on skin cells. P2X7 is present on keratinocytes, Langerhans cells, dermal dendritic cells, dermal macrophages, skin T lymphocytes and dermal fibroblasts. P2X7 activation on these cells induces a number of downstream events as indicated. P2X7 is absent on mast cells in normal skin, but can be upregulated during cutaneous disease. P2X7 may also be present on skin B cells, neutrophils, eosinophils and basophils (not shown), but direct evidence is lacking. Cell images were obtained from Servier Medical Art (http://www.servier.com/). ATP: Adenosine triphosphate; HLA: Human leukocyte antigen; IL: Interleukin; PGE2: Prostaglandin E2; RAGE: Receptor for advanced glycation end products; ROS: Reactive oxygen species; TGF: Transforming growth factor.

Figure 2 Activation of the P2X7 receptor and its regulation by CD39. Activation of P2X7 by extracellular ATP causes an influx of Ca²⁺ and Na⁺, and efflux of K⁺. Extracellular ATP can be degraded by cell surface CD39 to limit P2X7 activation on Langerhans cells, macrophages and mast cells. ATP: Adenosine triphosphate.