Irritant impact on cornified envelope and localisation

The outermost layer of the epidermis, the stratum corneum, presents a characteristic two-compartment structure, commonly named ‘bricks and mortar’ organisation: corneocytes are the bricks, embedded in a lipid-enriched extracellular matrix, the mortar, which in turn is organised into parallel stacks of lamellar bilayers, enriched in water-repellent lipids. The plasma membrane of corneocytes is composed of a solid and insoluble proteinrich scaffold, the cornified envelope (CE), which is cross-linked to extracellular lipids providing barrier function. In humans, most of the genes coding for CE components are located in a specific region of the chromosome 1, named epidermal differentiation complex.1

So far, numerous studies have been published showing the importance of CE in skin barrier functions. For example in a work published by EkanayakeMudiyanselage and collaborators,2 it has been shown that involucrin, a CE protein, is over-expressed upon permeability barrier disruption, suggesting a key role of this CE component in restoring cutaneous barrier function after an external aggression.

In the dermo-cosmetic field, the settingup of experimental conditions able to mimic an inflammatory state as well as a barrier functions deficient phenotype is crucial for the development of new dermocosmetic active ingredients.