The dermal barrier functions through several mechanisms:
- Physical Barrier: The stratum corneum, the outermost layer of the epidermis, forms a dense, protective layer of dead keratinized cells. These cells are held together by lipids, which create a waterproof seal.
- Chemical Barrier: The skin produces various antimicrobial peptides and enzymes that deter pathogen invasion. Sebum, an oily substance secreted by sebaceous glands, also has antimicrobial properties.
- Immunological Barrier: Langerhans cells in the epidermis and dendritic cells in the dermis act as antigen-presenting cells. They play a crucial role in initiating immune responses against invading pathogens.
- Microbiome: The skin is home to a diverse community of microorganisms that contribute to its defense mechanisms. These beneficial microbes can outcompete pathogenic organisms, thereby protecting the skin.
