Stratum corneum lipid–protein matrix

The stratum corneum lipid–protein matrix is the primary physical and chemical barrier of the skin, representing the final stage of epidermal differentiation. It is structurally organized according to the "brick and mortar" model, where protein-rich, non-viable cells called corneocytes (the bricks) are embedded in a continuous extracellular matrix of lamellar lipids (the mortar), primarily composed of ceramides, cholesterol, and free fatty acids. This matrix is essential for maintaining homeostasis by preventing excessive transepidermal water loss and protecting the body from environmental stressors, including pathogens, allergens, and chemical irritants. Dysfunction of the lipid–protein matrix is a central feature of various dermatological conditions, such as atopic dermatitis, psoriasis, and ichthyosis, where barrier impairment leads to inflammation and increased sensitivity. Therapeutic strategies often target this matrix to either restore its integrity using barrier-repair emollients and physiological lipids or to temporarily modulate its permeability using penetration enhancers to facilitate the topical delivery of other pharmacological agents.

Other names

Skin barrierEpidermal permeability barrierBrick and mortar modelIntercellular lipid matrixCorneocyte-lipid matrix

Barrier restoration through lipid replenishment, occlusion to reduce transepidermal water loss, humectancy to increase water binding, and keratolysis to promote desquamation.