Stratum corneum barrier (Corneocyte keratin and intercellular cement) (SC barrier)

The stratum corneum (SC) represents the terminal stage of epidermal differentiation and serves as the body's primary interface with the external environment. It is structurally organized according to the "brick and mortar" model, where keratin-filled corneocytes (the bricks) are embedded within a continuous matrix of intercellular lipids (the mortar), primarily composed of ceramides, cholesterol, and free fatty acids (StatPearls, 2023). The keratin filaments within the corneocytes provide structural rigidity and mechanical strength, while the intercellular cement regulates permeability and prevents excessive transepidermal water loss (TEWL) (PubMed, 2021). Dysfunction in these components is a hallmark of various dermatological diseases; for instance, a deficiency in barrier lipids or structural proteins like filaggrin leads to the inflammation and infection seen in atopic dermatitis (NIH, 2022). Pharmacological targeting of the SC involves the use of keratolytics to manage hyperkeratotic conditions by breaking down keratin and emollient lipids to restore the intercellular cement. These therapeutic interventions aim to normalize desquamation and enhance the skin's protective function against environmental stressors and pathogens.

Other names

Skin barrierEpidermal barrierBrick and mortar modelCorneocyte-lipid matrixPermeability barrier

Drugs targeting the stratum corneum act by either softening and dissolving the keratin (keratolysis), increasing the water-binding capacity of corneocytes (humectancy), or replenishing the intercellular lipid matrix to restore barrier integrity (emolliency).