Spermidine-induced recovery of human skin structure and barrier function by skin microbiome

An unbalanced microbial ecosystem on human skin is closely related to acne, atopic dermatitis, seborrheic dermatitis, or rosacea and has been associated with inflammation and immune response. However, little is known about the correlation between aging and the microbiome of human skin. Here, we investigated whether different Streptococcus species could improve various skin parameters. Metagenomic analysis with 16S rRNA sequencing revealed differential Streptococcus abundance in old and young individuals. Culture supernatant of Streptococcus infantis, Streptococcus pneumoniae, and Streptococcus mitis isolated from the facial surface of young individuals induced expression of genes associated with skin structure, barrier function, and lipid biosynthesis in vitro in human dermal fibroblasts and epidermal keratinocytes. This improved skin elasticity, moisture, and desquamation during clinical evaluation. Whole-genome analysis revealed the biosynthetic pathways enriched in the different Streptococcus candidates. In summary, we show that the skin microbiome has a strong potential in skin rejuvenation applications.