Pathophysiology of atopic dermatitis.

Only few diseases have been studied as extensively and on as many different levels in recent years as atopic dermatitis (AD). One of the reasons why AD is the focus of interest is that it is one of the most common chronic inflammatory skin diseases, affecting up to 30 % of children and 1-10 % of adults. Numerous complex alterations both on the genetic level as well as on the level of innate and adaptive immunity have been identified and form the basis for the characterization of different patient groups and the development of novel diagnostic and therapeutic approaches. Despite the complex pathophysiological and immunological differences, which are closely related to disease stage and severity, as well as the heterogeneity of individual trigger factors, treatment of AD - in particular that of moderate-to-severe AD - was long limited to merely symptomatic and relatively nonspecific immunosuppressive approaches. Since the approval of the first biologic for the treatment of moderate-to-severe adult AD (commercially available in Germany since late 2017), there has been some movement in the field of AD management. The present review highlights recent pathophysiologic insights. Advances in research allow for better characterization of certain patient subgroups and different disease manifestations. In addition, they form the basis of current and future developments in the field of precision medicine in AD.