First evidences of distinguishable bacterial and fungal dysbiosis in the skin of patients with Atopic Dermatitis or Netherton Syndrome.

Abstract Atopic dermatitis (AD) is an inflammatory skin disease in which epidermal barrier impairment, often owing to FLG null mutations, precedes immune hyper-responsiveness. Ichthyosis vulgaris (IV) is characterized by FLG null mutations and non-inflamed dry skin. Netherton syndrome (NS) due to SPINK5 null mutations is characterized by generalized erythroderma with scaling and atopic manifestations. The goal of this work was to evaluate associations between specific skin disease features, i.e. ichthyotic and/or atopic manifestations, and the skin bacterial and fungal microbiota. Taxon diversity showed greater variation in the bacterial microbiota than in the fungal microbiota in the skin diseases. The relative abundances of Firmicutes (Staphylococcus) and Actinobacteria (Corynebacterium) were augmented in IV, AD and NS, whereas those of Proteobacteria/Enhydrobacter and Bacteroidetes were reduced, regardless of body site. Furthermore, proportions of Staphylococcus were correlated with TEWL and serum IgE levels. Nevertheless, the skin of patients with low-mild AD was over-colonized with Staphylococcus epidermidis and not with Staphylococcus aureus. Ascomycota were increased in both AD and NS, but from expansion of different fungal species. Finally, the expansion of pathological bacteria in AD/NS might be supported by surrounding fungi. Thus, distinguishable bacterial and fungal skin dysbiosis in AD, NS and IV emphasizes disease-specific pathomechanisms.