Stratum corneum structural proteins and lipids (SC barrier)

The stratum corneum (SC) represents the outermost layer of the skin, serving as a critical interface between the body and the environment (StatPearls, 2022). It is composed of keratin-filled, non-viable cells called corneocytes (the bricks) surrounded by a complex extracellular matrix of lipids, including ceramides, cholesterol, and free fatty acids (the mortar) (Experimental Dermatology, 2008). This structure provides a robust physical and permeability barrier that prevents excessive transepidermal water loss and protects against mechanical insult, pathogens, and chemical irritants (Seminars in Immunopathology, 2007). In various dermatological conditions such as atopic dermatitis and psoriasis, the balance of these structural proteins and lipids is disrupted, leading to barrier dysfunction and inflammation (Experimental Dermatology, 2008). Therapeutic strategies often involve the use of keratolytics to manage hyperkeratosis, emollients to replenish the lipid matrix, and humectants to restore hydration to the keratinized tissue (PubChem, 2024).

Other names

Extracellular keratinEpidermal barrierSkin barrierCorneocyte envelopeIntercellular lipid matrix

Drugs targeting these components act via keratolysis (dissolving the intercellular cement and keratin), occlusion (forming a physical barrier to prevent water loss), or humectancy (binding water within the protein matrix) (Seminars in Immunopathology, 2007; PubChem, 2024).