The Cutaneous Barrier and Skin Infections

Abstract

The skin is the largest organ of the body, with an approximate surface area of 1.8 m2, which serves as the first line of defense against a multitude of environmental and pathogenic challenges, such as light, heat, ultraviolet (UV) radiations, microbes, toxic chemicals, traumatic injury, allergens and oxidative stress. It encompasses different functional layers, mainly the epidermis and dermis, containing various immune cells, implying a protective function that assists in developing junctional integrity and host defense. Besides this cellular diversity, skin provides a complex and interactive barrier system comprising different barrier elements, namely physical, chemical, microbiological and immunological. This intricate barrier system acts as a potent arsenal of weapons against potential threats from external stressors and aids in maintaining the functional integrity of the skin. An intact skin barrier system is crucial to warding off harmful agents (toxins, pollutants and allergens) and promoting tissue homeostasis and repair. A compromised skin barrier with distorted tight junctions demonstrates allergic and chronic infections. This chapter aims to describe the characteristics and functional aspects of different cutaneous barrier elements available against pathogenic infection and the link between altered skin barrier formation and pathogenesis. Moreover, it is intended to elucidate a highly interconnected network of cells and mediators that fine-tune skin defense mechanisms and monitor barrier integrity.