Scratching the surface: Improved health by adjusting skin microbiota?

Science has already made huge progress in understanding the workings (and failings) of human gut microbiota, but in the past decade, researchers are coming up for air and finding that there is as much to explore right on the surface of our bodies as there is on the inside. The skin and its microbiota are “shedding” light onto various pesky conditions from eczema to acne.

At the US National Human Genome Research Institute in Bethesda, Maryland, geneticists like Julie Segre are cautiously optimistic about the current line of research into skin-dwelling microbes. These microbes are so fascinating because they might be both the cause of skin disorders and also be the key to preventing them. Though scientist Julie Segre cautions that research is “really at the beginning stages,” it’s safe to say that any breakthrough would revolutionize not just our daily hygiene rituals, but entire industries such as health and beauty or cosmetics.

Inside out: first the gut, now the skin

Think of the gut like a playground full of diverse children coming into contact with one another: the gut is where the body’s largest community of microbes meet and play, with potential implications for nutrition, digestion and immunity. Like a playground, sometimes these meetings foster good (new friends!) and sometimes the not-so-good (fights over turf!). But let’s zoom out for a moment to consider another gathering place on our bodies, one where millions of microbiota assemble: The skin. It’s our body’s first line of defense against injury and illness, and thus a logical place for researchers to turn their attention. And just like the gut microbiota, “the composition of the skin microbiota is remarkably consistent over time” (Sohn 2018). And the most fascinating detail of all is that each and every person’s skin possesses its own unique constellation of microbes.

If you’ve perused our website or our other articles, you may be able to guess what phase of human life is the most crucial when establishing microbiota. It’s the first few months! This is indeed the hypothesis put forth by dermatologist Tiffany Scharschmidt in one of the first studies on how skin microbiota and the immune system interact. At the University of California, San Francisco, Scharschmidt “found that adult mice were tolerant to Staphylococcus epidermidis, a skin bacterium found commonly in people, when the microbes were allowed to colonize their skin soon after birth” (Sohn 2018). When, however, adult mice were confronted with S. epidermidis for the first time, their immune systems “mounted an inflammatory response, which can impede wound healing”, Scharschmidt says. In short, it’s likely that there is a phase in our lives in which exposure to microbes that we will encounter again and again is essential, and that phase is the first few years. This seems to imply that the sky is the limit when it comes to exposing our babies to good microbes early on in life. But is it easier said than done?

Well, not entirely. Take, for example, a 2009 study into inflammatory skin conditions like atopic dermatitis, the most common form of eczema: At UC San Diego, a team of immunologists and dermatologists led by Richard Gallo discovered that one species of Staphylococcus could offer protection from others. In the United States alone, 18 million people suffer from eczema. While you may know the tell-tale physical manifestations of the condition – inflamed, itchy patches of skin – did you also know that eczema is thought to increase the risk of infection? This is due to its bacterial component, S. aureus, which is found to increase on the affected areas of skin at the same time that the skin’s overall microbiota diversity decreases.

How can we be so sure? Findings from a 2017 study conducted at the US National Cancer Institute provide preliminary evidence. In the study, S. aureus bacteria from 18 children (some with, some without eczema) were colonized on healthy mice. Those mice who got the S. aureus bacteria from children who suffered from eczema eventually developed the inflamed, thickened skin characteristic of the condition.

Don’t pick! From eczema to acne vulgaris

While eczema is unpleasant enough for those who suffer from it, others find it perhaps even more difficult to keep their hands (and harmful bacteria) away from broken, acne-ridden skin. The condition known as acne vulgaris is not just physically painful, it carries a social stigma that can be emotionally scarring for its main victims – adolescents. “For decades, scientists have known that the bacterium Cutibacterium acnes (formerly Propionibacterium acnes) thrives on the skin of people with acne, which affects up to 85% of teenagers” writes Emily Sohn of nature: International journal of science. Researcher at UCLA Huiying Li found that while both acne-prone and healthy skin have similar “relative abundances” of C. acnes bacteria, it’s the population level differences in strain composition of the two skin types that make all the difference. There are more than 120 strains of C. acnes, so sequencing all the strains is a labor of love. Li does predict, however, that eventually medications could help acne sufferers by purging virulent strains of C. acnes or by targeting porphyrins (molecules that can trigger inflamma­tion in skin cells and are higher abundant in C. acnes strains that are found in acne patients)!

While still in its infancy, research into skin’s microbiota is a field that appeals to both scientists and consumers for its potential to transform both the health care industry and human practices. Although we live in a society in which odious conditions like eczema and acne carry cultural stigma, keep in mind that research in this field is motivated by intentions that go beyond upending beauty standards: For one, it aims to procure overall healthier bodies at skin level as a first line of defence against illness. Still, if in 10 years the healing creams and mists and facials containing new microbiota technology still fail to clear and balance our microbiomes from the outside, science may have to dive back under the surface to our gut for remedies to a healthy exterior.