Description
EOS is a ceramide found in the outer layer of the epidermis in mammals.
1 It is comprised of an ω-hydroxy very long-chain ceramide (C28-36) esterified to the essential fatty acid linoleic acid . The consecutive regio- and stereospecific oxygenation of the linoleate portion of EOS by 12(R)-lipoxygenase (12(R)-LO) and eLOX3 is essential for the maintenance of the epidermal barrier to prevent water loss. Following oxygenation, the oxidized linoleate is hydrolyzed, leaving the ω-hydroxy end of the very long-chain fatty acid to covalently bind the protein layer, forming the corneocyte lipid envelope and sealing the gap between the extracellular lipid lamellae and the cornified cell envelope of the corneocyte. EOS (d18:1/30:0/18:2) is a sphingolipid that has been found in intact and desquamated human stratum corneum as well as porcine epidermis.
2,3
References
1. Zheng, Y., Yun, H., Boeglin, W.E., et al. Lipoxygenases mediate the effect of essential fatty acid in skin barrier formation: A proposed role in releasing omega-hydroxyceramide for construction of the corneocyte lipid envelope J. Biol. Chem. 286(27),24046-24056(2011).
2. Long, S.A., Wertz, P.W., Strauss, J.S., et al. Human stratum corneum polar lipids and desquamation Arch. Dermatol. Res. 277(4),284-287(1985).
3. Wertz, P.W., Abraham, W., Cho, E.S., et al. Linoleate-rich O-acylsphingolipids of mammalian epidermis: Structures and effects of essential fatty acid deficiency Prog. Lipid Res. 25,383-389(1986).
