The microbiome varies from person to person and even anatomical locations on the same body, but a healthy microbiome is important in skin health. Peter Lio, MD, FAAD, discusses how microbiome dysbiosis factors in to atopic dermatitis and explains the evolution of the microbiome. Dr Lio is clinical assistant professor of dermatology and pediatrics at Feinberg School of Medicine at Northwestern University in Chicago, IL. He is a member of the Clinical Advisory Committee of the National Eczema Association.
Dr Lio: We know that the microbiome differs from individual to individual, but it also differs on a given individual's body. The microbiome of your mouth is very different to the microbiome here on your arm, which is different to the one on your legs or your groin, so it really has these little biomes that are different. We know that diversity of the microbiome really does seem to be a quality positive trait. Having a good diversity correlates with general health and stability.
What we see is, in a lot of disease states, that diversity number goes down and, typically, there is a pathogenic bacteria that seems to rise up. In the case of the skin, what we see is Staphylococcus aureus. This staph bacteria shoots up while diversity goes down. That seems to preclude a flare up.
This is incredible work. Heidi Kong did some of this work and codified it. This has been known to some degree for a while, but she did some beautiful studies about a decade ago where we turn this on its head. When I first learned about atopic dermatitis, we talked about the fact that the microbiome was abnormal, secondary to the skin. You have open oozing skin, so certain pathogens could take advantage of that. That's how we thought about it, that there was a risk of infection, but otherwise they were just colonizing.
Now, I think we see much more clearly that the state of the microbiome, its health is directly going to influence the skin overall and the disease. If you can help the microbiome, then in theory you might be able to prevent some flare‑ups, might be able to control the disease.
We know part of it is probably genetic, part of it is the environment where you grow up and the things you were exposed to. A chunk of it also is your current environment. You can change your microbiome depending on your lifestyle choices. We talk about people who are more fit and active as doing better overall. Part of this may have to do with the health in the microbiome.
We often will vilify certain foods as being bad, but maybe part of the reason foods are bad is because they can fuel the bad actors in the microbiome. Part of what we're feeding, we're feeding ourselves, but we're also feeding [laughs] microbiome, all the bacteria which outnumbers us, some number of times over unity—it's amazing, we used to say we're on number 10 to 1; I guess, it's probably in truth a little bit lower, but we're still outnumbered by bacteria. So, you're feeding your bacteria, and what you choose to put in your body and on your body can affect that.
Moisturizers can affect your microbiome. It's amazing. Now we're seeing a whole set of products that say, "We're microbiome‑friendly, or we’re microbiome‑supportive." When we put a preservative in a cream or a lotion to preserve it from spoiling by bacteria, but you put that on your skin, the good guys might get hurt, too. If you can help the microbiome then, in theory, you might be able to prevent some flare-ups and might be able to control the disease.
We do think the microbiome changes over time, and children and adults do have some differences between them. One thing that’s amazing is that even at like 1 week of life, you can make some predictions about the risk of developing atopic dermatitis years later by the state of the microbiome both on the state of the skin and, in particular, in the gut. The diversity of the microbiome early on seem to be a predictor or maybe is a major factor. You know, we're thinking if it is correlated, but maybe it's actually causated, there’s a causation connection, too, so we don't know. That's fascinating to think that maybe we could influence babies and fix their microbiome early, and maybe that would have an effect on the outcome later.