Shift in skin microbiota of Western European women across aging.

AIMS: The objective of our study was to compare the microbiota diversity between two different age groups of Western European women. METHODS AND RESULTS: Skin-swab samples were collected directly on the forehead of 34 healthy Western European women: 17 younger (21-31 years old) and 17 older individuals (54-69 years old). Bacterial communities were evaluated using the 16S rRNA gene sequencing. Data revealed a higher alpha diversity on the skin of older individuals compared with younger ones. Overall microbiota structure was different between the two age groups, as demonstrated by beta diversity analysis, which also highlighted a high interpersonal variation within older individuals. Furthermore, taxonomic composition analysis showed both an increase in Proteobacteria and a decrease in Actinobacteria on the older skin. At the genus level, older skin exhibited a significant increase in Corynebacterium and a decrease in Propionibacterium relative abundance. CONCLUSIONS: Our study revealed a shift in the distribution of skin microbiota during chronological aging in Western European women. SIGNIFICANCE AND IMPACT OF STUDY: Altogether these results could become the basis to develop new approaches aiming to rebalance the skin microbiota, which is modified during the aging process.

From the morphological to the transcriptomic characterization of a compromised three-dimensional in vitro model mimicking atopic dermatitis.

BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory skin disease in which skin barrier function is disrupted. In this AD environment, proinflammatory cytokines are upregulated, promoting a vicious circle of inflammation. Although several three-dimensional in vitro models mimicking AD have been published, no study has presented a fully characterized and controlled model of AD-related inflammation. OBJECTIVES: To develop and characterize, from the morphological to the molecular level, a compromised reconstructed epidermis (RE) mimicking AD-related inflammation in vitro. METHODS: Normal human keratinocytes were used to generate RE, treated or not with an inflammatory cocktail (polyinosinic-polycytidylic acid, tumour necrosis factor-α, interleukin-4 and interleukin-13). RESULTS: The inflammatory cocktail induces some modifications observed in patients with AD: (i) it leads to spongiosis; (ii) it alters early and terminal differentiation proteins; (iii) it increases thymic stromal lymphopoietin and interleukin-8 secretion by keratinocytes and (iv) it results in a specific gene expression pattern. CONCLUSIONS: The inflammatory context contributes to the morphological, functional and transcriptomic changes observed in AD skin. As a result, this compromised RE model shares some characteristics with those found in AD skin and thus can be used as a relevant tool for screening formulations and drugs for the treatment of AD.