Abstract
An unbalanced microbial ecosystem on the human skin is closely related to skin diseases and has been associated with inflammation and immune responses. However, little is known about the role of the skin microbiome on skin aging. Here, we report that the Streptococcus species improved the skin structure and barrier function, thereby contributing to anti-aging. Metagenomic analyses showed the abundance of Streptococcus in younger individuals or those having more elastic skin. Particularly, we isolated Streptococcus pneumoniae, Streptococcus infantis, and Streptococcus thermophilus from face of young individuals. Treatment with secretions of S. pneumoniae and S. infantis induced the expression of genes associated with the formation of skin structure and the skin barrier function in human skin cells. The application of culture supernatant including Streptococcal secretions on human skin showed marked improvements on skin phenotypes such as elasticity, hydration, and desquamation. Gene Ontology analysis revealed overlaps in spermidine biosynthetic and glycogen biosynthetic processes. Streptococcus-secreted spermidine contributed to the recovery of skin structure and barrier function through the upregulation of collagen and lipid synthesis in aged cells. Overall, our data suggest the role of skin microbiome into anti-aging and clinical applications.
Highlights
An unbalanced microbial ecosystem on the human skin is closely related to skin diseases and has been associated with inflammation and immune responses
Based on the metagenomic analysis, we hypothesized that S. infantis or some other unclassified Streptococcus species could be closely related to facial skin aging
The facial skin microbiome formed at birth changes gradually with aging, and any imbalance in their composition is closely related to skin diseases, such as atopic dermatitis, psoriasis, and acne[7,16,19,35,36]
Summary
An unbalanced microbial ecosystem on the human skin is closely related to skin diseases and has been associated with inflammation and immune responses. Skin aging is caused by a combination of intrinsic factors, such as changes in hormones, cellular metabolism, and immune responses, and external factors, such as exposure to pollutants and ultraviolet rays[9,10,11,12] They induce major physiological and physical changes in the skin, such as sagging, wrinkles, dryness, and low elasticity[10]. We observed that Streptococcus colonies are enriched in the facial skin of young Korean women (20–29 years old) and demonstrated their roles in the improvement of skin health through metagenomic analysis, in vitro assays using human skin cells, clinical analysis, and genomic analysis with validations (metabolic and cellular analyses). Our findings suggest the potential of the Streptococcus species to rejuvenate aged skin, thereby providing insights on the possible applications of the skin microbiome in clinical practice
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