Changes in the gut microbiome have a role in aging, and the activities of microbial species (generation of beneficial metabolites, versus generation of harmful inflammation) may be as important as lifestyle choices such as exercise when it comes to the pace of aging. Certainly there is good evidence for rejuvenation of the gut microbiome via fecal microbiota transplantation to improve health and extend life in short-lived laboratory species. Is the skin microbiome similarly important to the physical manifestations of skin aging? There is much less evidence here, as work on this microbiome in the context of aging lags somewhat behind investigations of the gut microbiome. Nonetheless, intriguing results such as those noted here are presently being produced by researchers.
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 the faces 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.