Human skin barrier lipids and keratin (SC barrier)

The human skin barrier, primarily located in the stratum corneum, consists of a brick and mortar structure where keratin-filled corneocytes (bricks) are embedded in a complex lipid matrix (mortar) composed of ceramides, cholesterol, and free fatty acids (StatPearls, 2023). This barrier is essential for preventing excessive transepidermal water loss and protecting the body from environmental pathogens, allergens, and chemical irritants (PubMed, PMID: 18306158). Keratins provide structural integrity and mechanical strength to the epidermis, while the lipid lamellae ensure permeability control (UniProt, P04264). Dysregulation or depletion of these components is a hallmark of inflammatory skin diseases such as atopic dermatitis and psoriasis, where the barrier is compromised (NIH, 2021). Therapeutic interventions often target this barrier through the application of emollient lipids to restore the matrix or keratolytic agents to modulate the shedding of keratinized cells (Journal of Clinical Medicine, 2022). Understanding the interplay between these lipids and proteins is crucial for developing effective topical delivery systems and barrier-repairing formulations (Wikipedia, Stratum corneum).

Other names

Stratum corneum barrierEpidermal barrierSkin moisture barrierCorneocyte-lipid matrixSkin permeability barrier

Therapeutic agents interact with the skin barrier through several mechanisms: occlusion (forming a physical film to prevent water loss), humectancy (drawing water into the stratum corneum), emolliency (filling gaps between corneocytes with lipids), and keratolysis (breaking down keratin aggregates to facilitate desquamation).