Skin lipid barrier

The **skin lipid barrier** refers to the specialized extracellular matrix of lipids within the outermost layer of the epidermis—the stratum corneum. This structure is composed primarily of ceramides, cholesterol, and free fatty acids arranged in highly organized lamellar layers between dead keratinocytes (corneocytes). The "brick-and-mortar" model describes corneocytes as bricks held together by this intercellular lipid mortar. The main functions are preventing excessive water loss from the body (transepidermal water loss), protecting against entry of pathogens/allergens/irritants from outside environments, maintaining hydration/homeostasis in deeper layers of skin tissue, supporting normal microbial flora on the surface ("microbiome"), and contributing indirectly to immune defense. Disruption or deficiency in these lipids leads to impaired function—manifesting clinically as dry/sensitive/inflamed skin conditions such as atopic dermatitis or eczema. Restoration strategies focus on replenishing lost lipids with topical formulations containing ceramides/cholesterol/fatty acids. Note: The "skin lipid barrier" is **not** a single molecule/receptor/enzyme/transporter but rather an essential structural feature formed by multiple molecules working together within tissue architecture. It should not be classified as a canonical therapeutic target like receptors or enzymes; instead it represents an important physiological system relevant for dermatology research and therapy development.

Other names

Lipid barrierStratum corneum lipid barrierEpidermal lipid barrierSkin permeability barrier

Drugs do not directly target the "skin lipid barrier" as a receptor or enzyme. Instead, topical agents may restore its function by replenishing key lipids like ceramides and fatty acids.