Distribution of Bioactive Lipid Mediators in Human Skin.

Skin produces bioactive lipids that participate in physiological and pathological states, including homeostasis, induction, propagation and resolution of inflammation. However, comprehension of the cutaneous lipid complement, and contribution to differing roles of the epidermal and dermal compartments, remains incomplete. We assessed the profiles of eicosanoids, endocannabinoids, N-acyl ethanolamides and sphingolipids, in human dermis, epidermis, and suction blister fluid. We identified 18 prostanoids, 12 hydroxy-fatty acids, 9 endocannabinoids and N-acyl ethanolamides, 21 non-hydroxylated ceramides and sphingoid bases, several demonstrating significantly different expression in the tissues assayed. The array of dermal and epidermal fatty acids were reflected in the lipid mediators produced, while similarities between lipid profiles in blister fluid and epidermis indicated a primarily epidermal origin of suction blister fluid. Supplementation with omega-3 fatty acids ex vivo showed that their action is mediated through perturbation of existing species and formation of other anti-inflammatory lipids. These findings demonstrate the diversity of lipid mediators involved in maintaining tissue homeostasis in resting skin, and hint at their contribution to signalling, cross-support and functions of different skin compartments. Profiling lipid mediators in biopsies and suction blister fluid can support studies investigating cutaneous inflammatory responses, dietary manipulation, and skin diseases lacking biomarkers and therapeutic targets.Journal of Investigative Dermatology accepted article preview online, 10 February 2015. doi:10.1038/jid.2015.41.