Development of a skin microbiome diagnostic method to assess skin condition in healthy individuals: Application of research on skin microbiomes and skin condition.

Objective: Skin microbiomes vary across individuals. They are known to play essential roles in maintaining homeostasis and preventing infectious pathogens. In recent years, cosmetic product development has begun to focus on the relationship between skin microbiomes and skin conditions. However, the statistical methods used in many studies include the standard t-test and small-scale correlation analysis, which do not take into account the internal correlation structure in data on skin microbiomes and skin features. In this study, we aimed to understand the relationship between skin microbiomes and skin features by analysing complex microbiomes and skin data.

Methods: We obtained data on 19 skin characteristics and skin microbiomes based on 16s ribosomal RNA (16S rRNA) gene analysis of 276 healthy Japanese women. We then performed the principal component analysis (PCA), a method that takes into account the internal correlation structure, on 234 panels of them that did not contain outliers or missing values. We confirmed the relationship between skin microbiomes and skin features with principal component regression analysis and hierarchical clustering analysis (HCA).

Results: The principal component regression analysis showed strong relationships between skin microbiomes and sebum-related skin characteristics and skin pH. In the HCA, the female panel was classified into two major groups based on the skin microbiome. Furthermore, there were significant differences in sebum-related skin characteristics and the way skin condition changes with ageing between those groups, suggesting the possibility of measuring skin condition and age-related skin risk based on microbiome data. In addition, sebum-related characteristics differed significantly among middle-aged participants, suggesting a strong relationship between skin microbiomes and sebum-related characteristics.

Conclusion: Analysis of skin condition and skin microbiome in Japanese women, taking into account the correlation between variables, showed that skin microbiome was significantly related to the number of pores and the amount of sebum. Furthermore, it was suggested that the skin condition and the way the skin condition changes with ageing may differ depending on the type of skin microbiome. The finding of a relationship between skin condition and skin microbiome suggests the possibility of proposing a new beauty method focusing on the skin microbiome in the future.