Skin Barrier Health: Regulation and Repair of the Stratum Corneum and the Role of Over-the-Counter Skin Care.

The epidermis functions as a physical barrier that separates the inner body from the outside environment. The outermost layer of the epidermis, the stratum corneum, plays a key role in maintaining this barrier. There are numerous biochemical changes that take place to and in the keratinocyte as it migrates from the bottom, or startum basale, to the top layer of the epidermis in order for this barrier to function appropriately. In addition, external and internal factors, such as irritants and underlying medical diseases, can also affect the stratum corneum, both of which can potentially lead to disruption of barrier function and ultimately skin pathology. In this article, we will review keratinocyte biology as it relates to the formation and function of the stratum corneum. We will also review stratum corneum structure, physiology, and the impact of chemical agents and defective stratum corneum components that can lead to skin disease. Finally, we will briefly discuss how moisturizers repair defects in the stratum corneum and restore barrier function. J Drugs Dermatol. 2016;15(9):1047-1051.