Molecular events occurring behind ultraviolet-induced skin inflammation

We reviewed a recent advance in the studies of the molecular mechanisms for 'ultraviolet responses', paying special attention to two transcription factors, nuclear factor kappa B and p53, and to a balance noted between an anti-apoptotic phosphatidylinositol 3-kinase-Akt pathway and its inhibitory ceramide-caveolin-1 pathway. These studies were mostly carried out using in vitro or animal models. On the basis of these results, we determined that phase by phase molecular events clarified in these studies correspond well with the three phases of ultraviolet-induced inflammation observed, i.e. the early vasodilatory phase, the second inflammatory phase in which many inflammatory cells such as neutrophils and T cells accumulate in the skin, and the last regressive phase based on several anti-inflammatory events.