UV Inflammation and Anti-Inflammatory Drugs

Abstract

The activation of vitamin D synthesis remains the only well established physiological role of ultraviolet radiation (UV) in the skin (Omdahl & de Luca, 1973) although ultraviolet irradiation has long been a part of dermatological therapy. Harmful actions include production of inflammation, epidermal hyperplasia and carcinomatous changes and degenerative changes in the connective tissue of the dermis. Interest in the cellular and molecular action of UV in skin has been heightened by a number of new factors. There is mounting concern about the impact of environmental factors on the amount of solar UV, especially in the shorter wavelength range, which reaches the earth’s surface. The increased use of halogenated hydrocarbon aerosol propellants and refrigerants, and even the advent of supersonic jet aircraft has led to the prediction that the ozone barrier layer in the stratosphere may be weakened. This, it is claimed, may permit exposure to harmful shorter wavelength UV, with consequent increased incidence of skin cancer (Goldsmith, Tuck, Foot, Simmons & Newson, 1973). Greater use is now being made of ultraviolet in the treatment of chronic skin disease. In particular, the advent of photochemotherapy for psoriasis which involves oral administration of 8-methoxy psoralen followed by irradiation with long wavelength UV 365nm (PUVA) (Parrish, Fitzpatrick, Tanenbaum and Pathak, 1974), has been an important development. Data on the pathophysiological effects of UV in human skin is therefore urgently required.