Epidermal barrier function (specifically, stratum corneum-mediated moisture and irritant exclusion)

"Moisture/irritant exclusion from epidermal layer" is not a single molecule or receptor but rather describes a **complex physiological function** performed by the outermost layer of the skin—the **stratum corneum**—and its associated structures. The stratum corneum acts as the principal physical and chemical **barrier to water loss and entry of external irritants or pathogens**[1][3][5]. This protective role is achieved through an organized structure composed primarily of flattened dead cells called **corneocytes**, embedded in a lipid matrix rich in ceramides, cholesterol, and fatty acids[1][2][3]. Key proteins such as filaggrin, involucrin, loricrin, desmogleins/desmocollins (components of desmosomes/corneodesmosomes), and enzymes involved in lipid processing are essential for maintaining this barrier[1][2][5]. Disruption or dysfunction in any component—whether due to genetic mutations affecting structural proteins/lipids or environmental insults—can lead to increased transepidermal water loss (**TEWL**) and heightened susceptibility to irritation/infection. While many drugs or topical agents aim to support this function by enhancing lipid synthesis or keratinocyte differentiation[2], there is no single molecular target that corresponds directly with "moisture/irritant exclusion from epidermal layer." Instead, it represents an emergent property arising from multiple molecular pathways working together. Because this entry does not refer to a specific molecule/receptor/enzyme/transporter but rather a physiological process involving many components, it should be flagged as incorrect for structured drug-target databases.

Other names

Skin barrier functionStratum corneum permeability barrierEpidermal permeability barrier