EPIDERMAL FATTY-ACID OXYGENASES ARE ACTIVATED IN NON-PSORIATIC DERMATOSES

The extent of epidermal fatty acid oxygenase activation in non-psoriat ic dermatoses and the nature of these oxygenases are not known. The mo nohydroxylated fatty acid derivatives produced in vivo and trapped in skin scales or produced in vitro by oxygenases preserved in scales wer e analyzed by high performance liquid chromatography in 10 patients wi th non-psoriatic dermatoses. Evidence for 15-lipoxygenase activation i ncluded the finding of 15(S)-hydroxyeicosatetraenoic acid (HETE) in sc ales from seven patients and the production of 15(S)-[C-14]HETE and 13 (S)-[C-14]hydroxyoctadecadienoic acid (HODE) during scale incubations, respectively, with [C-14]arachidonic and [C-14]linoleic acid. Evidenc e for the activation of an arachidonic acid 12(R)-oxygenase included t he finding of 12(R)-HETE in scales from eight patients and the product ion of 12(R)-[C-14]HETE during scale incubations with [C-14]arachidoni c acid. 13-HODE was the predominant fatty acid derivative present in s cale extracts; its lack of enantiopurity (mean S/R = 3.1) and the subs tantial formation of 9-HODE (mean S/R = 0.6; 9/13-HODE = 0.43) suggest its derivation from 15-lipoxygenase and a second oxygenase. The level s of 15(S)-HETE and 12(R)-HETE had a 125- to 144-fold range and were h ighest in scales from a patient with erythroderma and in three psoriat ic scale samples similarly analyzed. These findings indicate that 15-l ipoxygenase, most likely of keratinocyte origin, and an arachidonic ac id 12(R)oxygenase of unknown type and cell origin are activated in div erse dermatoses.