Microbiome in atopic dermatitis.

Atopic dermatitis (AD) is a common chronic inflammatory skin disease affecting ~10-20% of the general population. AD is characterized by disturbances in epidermal barrier function and hyperactive immune response. Recently, changes in the skin and intestinal microbiome have been analyzed in more detail. The available data suggest a link between disturbed skin microbiome and course of the disease. Flares of the disease are associated with an expansion of Staphylococcus aureus on lesional skin and a substantial loss of biodiversity in skin microbiome. Staphylococci exoproteins and superantigens evoke inflammatory reactions in the host. Skin microbiome includes superficial stratum corneum that is affected by environmental factors such as exposure to germs and cleansing. Available evidence argues for a link between epidermal barrier impairment and disturbances in skin microbiome in AD. In contrast to skin microbiome, intestinal microbiome seems to become stabilized after infancy. There is also a significant heritable component for intestinal microbiome. The microbial taxa, relative percentages and quantities vary remarkably between the different parts of the intestinal tract. Early intestinal microbial colonization may be a critical step for prevention of further development of AD. Skin barrier-aimed topical treatments help to develop a neo-microbiome from deeper compartments. Probiotics, prebiotics and synbiotics have been investigated for the treatment of AD, but further investigations are needed. Targeted treatment options to normalize skin and intestinal microbiome in AD are under investigation.