Bradykinin-induced prostaglandin synthesis is enhanced in keratinocytes and fibroblasts by UV injury.
Ultraviolet (UV) light exposure substantially modifies the host immune response, in part through the synthesis of prostaglandins. Work examining the mechanisms by which UV irradiation stimulates prostaglandin synthesis has focused on mediators that increase in quantity after irradiation. The present work demonstrates that UV irradiation injury increases the sensitivity and maximum response of keratinocytes to bradykinin, suggesting that agonist quantities need not increase in injured tissue to contribute to inflammation. The ability of UV injury to increase bradykinin-stimulated prostaglandin synthesis is not limited to keratinocytes, as irradiation produced a similar response in fibroblasts. Receptor binding studies demonstrate that the enhanced response of irradiated cells is not due to increased bradykinin binding. These data suggest that UV irradiation may cause cells to increase their response to an array of inflammatory mediators present in injured tissue, whether or not the quantity of the mediator increases.