Key players, mechanisms and new perspectives
By Anaïs BONNEFOY
The skin forms the body’s first line of defence against the environment. Exposed daily to a wide range of external stressors, it activates defence mechanisms that combine its barrier function with innate and adaptive immunity.
A well-coordinated immune response eliminates potentially harmful agents whilst maintaining tolerance towards the commensal microorganisms of the microbiota and the body’s own constituents. Once the threat has been averted, the immune response must return to a resting state in order to prevent the development of persistent inflammation. Skin immunity is thus based on a balance between surveillance, activation and regulation.
Recent research highlights several distinctive features of this local defence mechanism: the persistence of an immune memory following inflammatory episodes, the influence of the microbiome on the regulation of immune responses, the immune privilege of certain structures such as the hair follicle, and the close interaction between immune cells and the nervous system.
