ISSN: 2471-9315
Pierre-Yves Morvan and Romuald Vallee
Background: Due to its immune system, the skin constitutes the first barrier against environmental attack such as chemical and physical agents or bacteria. The bacteria, viruses, archaea and fungi present on the superficial layers of the skin correspond to the cutaneous microbiota. Its composition is crucial to the balance of the immune system. It has already been shown that the composition of the microbiota affects the development of diseases such as atopic dermatitis (since an increase in Staphylococcus aureus has been described), but also diabetes and obesity. This microbiota imbalance (or dysbiosis) is mainly related to individual factors (age), diet, environmental (climate) and behavioral factors (hygiene, consumption of antibiotics).
Aim: In our study, we are more interested in the effect of a stressful lifestyle on skin microbiota, and more especially on skin bacteria.
Methods: We studied the skin microbiota from the faces of 70 healthy human subjects (aged 25 to 45 years). Firstly, we worked with 2 groups of 20 volunteers selected according to their stress level, using a validated stress score evaluation, known as the Perceived Stress Scale (PSS). Secondly, we tested the effect of a topical treatment on the skin microflora of a group of 30 volunteers who displayed a high stress index (PSS>27).
Results: We identified a bacterial signature of stressed individuals in comparison to unstressed individuals in term of richness and diversity. We also identified some species that are more prevalent in stressed individuals, especially acidic and anaerobic bacteria, in relation to modified skin parameters (decreased skin pH, increased redness and a higher level of blemishes). We then identified some benefits to the skin microbiota of stressed individuals from a topical treatment, with an improvement in skin parameters (increased pH, reduced redness and fewer blemishes).
Conclusion: This original study on healthy human skin microbiota will serve to direct future research addressing the role of skin microbiota in healthy people, and metagenomic projects addressing the complex physiological interactions between the skin and the microbes that populate this environment.