Stratum corneum intercellular cement and keratin matrix

The stratum corneum intercellular cement and keratin matrix constitute the primary physical barrier of the human skin, functioning as the outermost layer of the epidermis (StatPearls, 2023). This structure is frequently described using the brick and mortar model, where corneocytes (the bricks) are embedded in a lipid-rich intercellular matrix (the mortar) (PubMed, PMID: 18306158). The keratin matrix within the corneocytes provides structural rigidity and mechanical strength, while the intercellular cement, composed of ceramides, cholesterol, and free fatty acids, regulates permeability and prevents excessive transepidermal water loss (NIH, PMID: 22435313). Its primary biological role is to shield the body from environmental pathogens, allergens, and chemical irritants. Disruptions in this matrix are central to the pathogenesis of inflammatory skin diseases such as atopic dermatitis and psoriasis, where barrier dysfunction leads to increased sensitivity and inflammation. Therapeutic strategies targeting this complex include the use of keratolytics like salicylic acid to break down the keratin matrix and emollients to replenish the lipid cement. Additionally, the integrity of this matrix is the principal factor determining the rate of percutaneous absorption for topically applied drugs.

Other names

Skin barrierEpidermal barrierCorneocyte-lipid matrixBrick and mortar model of the skinStratum corneum extracellular matrix

Keratolysis of the keratin matrix to promote desquamation and replenishment of the intercellular lipid cement to restore barrier integrity and hydration.