Lipoxygenases (LOXs) are enzymes likely to be involved in corneocyte lipid envelope formation and skin barrier function. In humans, mutations in epidermis-type lipoxygenase 3 ( eLOX-3) and 12R–lipoxygenase ( 12R-LOX) genes are associated with autosomal recessive congenital ichthyosis (ARCI), whereas deletion of these genes in mice causes epidermal defects. LOXs also represent a matter of interest in psoriasis as well as in cancer research. However, their expression as well as the exact role of these enzymes in normal human skin have not been fully described. Our goal was to characterize the expression of epidermal LOXs in both normal human skin and Tissue-Engineered Skin Substitutes (TESS) and to consider TESS as a potential model for LOX functional studies. Staining for epidermal differentiation markers and LOXs was performed, in parallel, on normal human skin and TESS. Our results showed similar expression profiles in TESS when compared with native skin for e-LOX3, 12R-LOX, 12S-lipoxygenase (12S-LOX), and 15-lipoxygenase 2 (15-LOX-2) but not for 15-lipoxygenase 1 (15-LOX-1). Because of their appropriate epidermal differentiation and LOX expression, TESS represent an alternative model for future studies on LOX function.

Stratum Corneum (SC) formation in the human epidermis requires lipid processing. Lipoxygenases (LOXs) such as 12R-Lipoxygenase (12R-LOX) and Epidermis-type lipoxygenase 3 (eLOX-3) contribute to this process. Mutations in their genes cause Autosomal Recessive Congenital Ichthyosis (ARCI) in patients. On the other hand, 12S-lipoxygenase (12S-LOX) is expressed in the human epidermis, but its role still remains to be clarified. The involvement of eLOX-3, 12R, and 12S-LOX in conditions or processes such as skin photodamage, wound healing, psoriasis, and atopic dermatitis is suggested but still remains unclear. In order to eventually gain a better understanding of the role of these LOXs in such processes, models of Tissue-Engineered Skins (TESs) with an impaired expression for the native form of either eLOX-3, 12R-LOX, or 12S-LOX were produced using CRISPR-Cas9(D10A) technology. All three models showed impaired keratinocyte differentiation and changes in the prevalence or the size of lipid droplets within the most superficial layers, thus reproducing features observed in ARCI and supporting a role for 12S-LOX in SC formation. Since eLOX-3 and 12R-LOX depleted TES’s reproduced features observed in ARCI, such models can be considered as reliable tools for the functional studies of these LOXs in the human epidermis.