UVB-generated Microvesicle Particles: A Novel Pathway by Which a Skin-specific Stimulus Could Exert Systemic Effects.

Ultraviolet B radiation (UVB) exerts profound effects on human skin. Much is known regarding the ability of UVB to generate a plethora of bioactive agents ranging from cytokines and other bioactive proteins, lipid mediators and microRNAs. It is presumed that these agents are in large part responsible for the effects of UVB, which is only absorbed appreciably in the epidermis. However, the exact mechanism by which these bioactive agents can leave the epidermis are as yet unclear. This review addresses the potential role of microvesicle particles (MVP) as UVB signaling agents through transmitting biologic mediators. New data are provided that UVB treatment of human skin explants also generates MVP production. We hypothesize that UVB production of MVPs (UVB-MVP) could serve this important function of transmitting keratinocyte-derived bioactive agents. Moreover, we propose that UVB-MVP formation involves the lipid mediator platelet-activating factor. This novel pathway has the potential to be exploited pharmacologically to modulate UVB effects.