[Lipid mediators]

Platelet-activating factor antagonist WEB 2086 inhibits ultraviolet-B radiation-induced dermatitis in the human skin

It has been suggested that platelet-activating factor (PAF) plays a role in the pathomechanisms of various inflammatory diseases. In an experimental animal model we demonstrated earlier that a selective PAF receptor antagonist gel inhibits ultraviolet-B (UVB) light-induced edema in mouse ears. The goal of our present investigation was to determine whether locally applied WEB 2086, a selective PAF receptor antagonist, alters the dermatitis-causing effect of UVB light on human skin. We induced dermatitis in healthy volunteers by irradiating their skin with UVB light in increasing doses. The irradiated area was treated with WEB 2086 gel (3%) or with a placebo. Erythema was measured spectrophotometrically after 24 and 48 h. After both 24 and 48 h, the WEB 2086 gel significantly inhibited the UVB light-induced erythema at each radiation dose in comparison with the placebo. The PAF antagonist gel therefore proved to be effective against UVB-induced dermatitis. Our results may help to understand the relative importance of mediators in UVB-induced dermatitis and might perhaps pave the way to better therapeutic modalities in this condition.

The role of innate immunity in the pathogenesis of acne

Acne is a multifactorial disease of the pilosebaceous follicle. The most significant pathogenetic factors of acne are: abnormal ductal keratinization, increased sebum secretion, abnormalities of the microbial flora and inflammation. The pilosebaceous unit is an immunocompetent organ. Keratinocytes and sebocytes may act as immune cells capable of pathogen recognition and abnormal lipid presentation, and they might have an important role in initiating and perpetuating the activation of both innate and adaptive immune responses. The elements of the skin immune system are involved in the development of both noninflammatory and inflammatory acne lesions.