The Role of Tight Junctions in Skin Barrier Function and Dermal Absorption

The document from 2016 discusses the skin's role in protecting the body from external threats and preventing water and solute loss, highlighting the importance of the skin's complex barrier system, which includes the stratum corneum, tight junctions, the microbiome, chemical, and immunological barriers. These barriers are interconnected and can influence each other, particularly in response to external manipulation or skin diseases. The focus is on the mechanical barriers, the stratum corneum and tight junctions, which are crucial for drug delivery and skin absorption. Tight junctions, located in the stratum granulosum and the companion cell layer of hair follicles, are emphasized for their central role and rapid response to stimuli. The document summarizes current knowledge on tight junction function in the epidermis and hair follicles, their interaction with other skin barrier components, and their significance in health, disease, and drug delivery, including examples of tight junction modulators.