What is already known
The skin serves as a barrier, protecting the body from infections and harmful invaders. Beneficial microbes, or commensals, also play a key role in maintaining this defense by interacting with skin cells and releasing protective molecules. However, the impact of these microbes on skin health remains unclear.
What this research adds
Researchers used a community of 50 bacterial species found on healthy human skin to colonize germ-free mice with impaired skin barrier. These microbes produce metabolites that strengthened the animals’ skin barrier and boosted repair. These effects were linked to the activation of a key pathway for skin health. Blocking this pathway reduced the beneficial effects on skin health, whereas a cocktail of microbial metabolites improved skin repair in both mice and human skin cells grown in the lab.
Conclusions
The findings suggest that specific microbial metabolites can lead to new therapies for skin barrier disorders such as eczema and psoriasis.
The skin serves as a barrier, protecting the body from infections and harmful invaders. Now, a study done in mice found that certain skin bacteria produce molecules that help repair and strengthen the skin’s protective barrier.
The findings, published in Cell Chemical Biology, suggest that specific microbial metabolites can lead to new therapies for skin barrier disorders such as eczema and psoriasis.
Commensals, or helpful microbes that live on the skin, play a key role in maintaining the body’s protective barrier by interacting with skin cells and releasing beneficial molecules. However, the impact of these microbes on skin health remains unclear.
Researchers led by Aayushi Uberoi at the University of Pennsylvania in Philadelphia investigated how skin microbes influence the skin’s barrier function and repair. To do so, they used a community of 50 bacterial species commonly found on healthy human skin, dubbed Flowers’ Flora 50 (FF50), to colonize germ-free mice with impaired skin barrier.
Skin health
The FF50 microbes successfully colonized the mice’s skin, matching the behavior of human skin bacteria, the researchers found. Mice colonized with FF50 microbes showed reduced water loss and improved healing.
Further experiments showed that FF50 microbes can metabolize the amino acid tryptophan into compounds that benefit the skin barrier. By analyzing the genomes of the FF50 bacterial community, the researchers identified enzymes that transform tryptophan into molecules such as indole-3-acetic acid and indole pyruvate, which have been shown to strengthen the skin barrier.
Tryptophan-derived metabolites produced by skin microbes could activate a cellular pathway, called the aryl hydrocarbon receptor (AHR), that is crucial for skin cell health. When the AHR pathway is activated, it promotes skin cell differentiation and the formation of tight junctions between cells, which are crucial for a healthy skin barrier.
Personalized therapies
A cocktail of tryptophan-derived metabolites improved skin repair in both mice and human skin cells grown in the lab, while blocking the AHR pathway reduced the beneficial effects on skin health.
The findings indicate that microbial metabolites could be key to new treatments for skin conditions, particularly those that involve a compromised skin barrier, the authors say.
“A comprehensive understanding of the mechanisms driving interactions within the skin ecosystem could lead to innovative, personalized, and cost-effective therapies that leverage host-microbiome interactions.”
