Over the past few decades, there has been a major paradigm shift in our thinking about microorganisms (bacteria, virus, yeast, etc.) and the role they play in our health and wellbeing. We have evolved from the “germ theory of disease,” pre-21st century, to embracing the idea that microorganisms, especially bacteria, are not all disease-causing, and in fact can be quite beneficial, even crucial, to our health. We now know that a healthy, balanced microbiome – the collection of microorganisms that that colonize our skin and gut – plays an essential role in establishing our immune system and maintaining good health (and good skin).
While the fields of microbiology and dermatology have long recognized that our skin is the home to a myriad of bacteria, fungi, viruses, archaea, and small arthropods, it’s only now that we understand the critical role these colonies play in human health and disease. Although less well characterized than the gut microbiome, the skin microbiome is emerging as a key player in our health and development, and may even lend to new insights into disease management.
SMD’s Dr. Shala Fardin has a particular interest in the skin microbiome, and recently co-authored a book chapter on the skin microbiome’s role in Acne and Rosacea. She notes that skin microbiome research has emerged as an important window to discovering new and novel ways to treat the skin. There may be innovative treatment options for conditions like acne and atopic dermatitis on the horizon that focus on managing specific microbes at the strain level, and even monitoring them in real-time to reduce flare-ups. There are even specific bacteria strains linked to reduction in wrinkles and aging. Companies like La Roche-Posay have already introduced ingredients to support our skin microbiome in their Lipikar AP+ balm, and our new Clarity Rx line at SMD (currently available at the clinic only) has products that work to balance the microbiome as well.
What is the skin microbiome specifically?
Our largest organ is home to vast populations of microbes and mites that inhabit our entire body; there isn’t a fold or crevice that isn’t sprawling with millions of little creatures. In a square centimeter of skin, it is estimated that over 100 distinct species comprise a total of 1 million bacteria, and there are up to a billion microorganisms colonizing this space if you factor in fungi, mites, and viruses. Furthermore, this means there are billions of genes that affect our daily life, vs our own 20,000 genes within our own cells.
Most of these microbes are stable over our adult lifetime and commensal – in other words, they are symbiotic and work with others to keep their host (us) healthy and safe. In fact, proper colonization of our skin by microbes early in life plays a critical role in promoting our innate host immune system, which acts as our first-line defense against infections or environmental changes, such as pollution or UV exposure.
For example, Staphylococcus epidermidis (S. Epidermidis) of the Staphylococcus species is known to be one of our closest friends. This bacteria is found on healthy skin, and works by releasing antimicrobial peptides (AMPs), which inhibit the invasion of pathogens.
While S. Epidermidis might be an important ally, certain toxic strains of Propionibacterium acnes (P. acnes), also known as Cutibacterium acnes, can stir up trouble in their own neighborhood. With proper conditions, these inflammation-causing microbes, commonly found in the sebum-rich “pores” such as on our facial skin, can cause conditions such as acne. Indeed, several microorganisms on our skin can change from being commensal to pathogenic (causing disease) depending on the skin’s conditions.
A diverse microbiome is a healthy microbiome
While there is no perfect “microbiome” and each of us have our own unique signature set of microorganisms, the most important aspect seems to be diversity. When we’re lacking diverse populations of bacteria, we become more susceptible to inflammation. The same can be said if we have an unhealthy gut microbiome, which can also lead to inflammation and disease, and even effect our mood (most of our body’s serotonin is actually made in our gut due to the influence of gut bacteria) As we learn more about this fascinating world of these microorganisms, we are realizing that these systems are more and more connected, termed the “gut-brain-skin axis.”
The next time you lather up in the shower, try to appreciate all those hard-working healthy microbes on your skin (and thus avoid using harsh, antibacterial soap all over your skin, unless recommended by your doctor to treat a specific condition.) And consider how we are all truly connected to our environment via our microbes, as it is yet to be determined is how we are affecting our very own microbiome due to changes in climate, pollution, loss of green spaces, diet, antibiotic use and other environmental factors.
We will continue to follow this interesting area of research and keep you updated as proven treatments emerge. Stay tuned for part two of this series where we will dive into what microbiome skincare is about, the trends we’re seeing, and what the future may look like in terms of innovation.
Written by Maya & Shala Fardin, MD
Reviewed by Shala Fardin, MD & Ashley Smith, MD
References:
1. Kong, Heidi and Julia Segre. “Skin Microbiome: Looking Back to Move Forward.” Journal of Investigative Dermatology, vol. 3, no. 3, March 2012, pp. 933-939.
2. Fardin, Shala and Janette Kerri. “Practical Applications in Acne and Rosacea.” Integrative Dermatology, 2021.