Dr Tina Meder, cosmetic dermatologist, founder of Meder Beauty and GetHarley practitioner on microbiome and skin.
The Human Microbiome Project (a US National Institutes of Health research initiative to improve understanding of the microbiota involved in human health and disease) completely changed our perception of the skin as an organ – now it’s seen as an ecosystem including the whole genome of bacteria, fungi, viruses and protozoa happily living on the skin. We are living in co-existence depending on each other – microbiome cannot live without a host as a human body, but we cannot live without a microbiome as well because too many functions of our skin and body in total are outsourced to our “micro-friends”.
The microbiome and the human body represent for me the perfect analogy of the planet and humanity. We are the microbiome of the planet Earth alongside animals, birds, marine life and all flora. Probably we became too aggressive last time, so our planet doesn’t feel well. We should care about our planet to stay safe so the planet can care about us. Imagine the planet is conscious and has become aware of humanity.
Exactly what happened with a Human Microbiome project when we as a planet discovered the importance of our microbiome. By taking care of the microbiome, we are helping our skin perform its functions better without using its own resources. Healthy microbiome protects our skin, helps to hold water, oxygenate it, and produces the necessary elements to build a structure. All we need to do is feed it and keep it happy and balanced.
The microbiome is amazingly similar to human society. It functions better while it’s diverse. It forms collaboration. Individual bacteria’s behaviour is different from collective. Increased population density makes bacteria and viruses more aggressive, and decreased density calms them down.
Curiously, the vast majority of microorganisms in the skin microbiome are commensals and facultative flora, while no more than 200 species are true pathogens. Recent research ascertains that the changes in the microbiome can create favourable conditions for and be a key factor in the development of infections. As a collective microbial genome, the microbiome is an example of very complex and diverse interactions between various microorganisms, including interspecies relations between viruses, fungi, bacteria and parasites.
Microorganisms colonise the skin at the moment of birth. A key role is played by vaginal microflora picked up by the baby when they move through the birth canal. The skin microbiome of C-section babies is most similar to the microflora of their mother’s stomach skin. This initial colonisation in the first postpartum hours defines the immune tolerance to commensal microbes and is most important for the formation of adapted immune responses.
Numerous studies resulted in a new approach to improving the immune response of caesarean babies by providing contact not only with the mother’s skin but also with her vaginal flora in order to activate the development of a healthy microbiome. Skin colonisation continues in the lactation period, which is why in the first days after the birth, the baby should have as much skin contact with the mother as possible – with as little clothes covering up the body as possible. At the same time, environmental microbes are picked up by the baby’s skin all over the body, with the simultaneous formation of ‘internal’ and ‘external’ microbes’ collective genome. During this short time in the first few days of life, the rapid development of highly activated regulatory T-cells occurs in the newborn’s skin. The inhibition of T-cells results from acquiring tolerance to commensals, which is a key factor in the development of the skin’s local immunity not just at this particular moment but in the future life as well. In fact, the first days of a newborn’s life lay the foundation to the future complex balance of commensal microbes populating the skin and forming a genetically unique microbiome which is just as much of a personal identifier as a fingerprint. However, if the development of T-cells is disturbed in the first days of life, it can lead to various health problems and diseases.
Throughout human life, the skin’s keratinocytes continue to sample the microbiome using a combination of recognition receptors. The skin’s immune response is basically a constant interaction between keratinocytes, the skin’s immune cells and microbes, modulated by AMPs, cytokines, chemokines and microbes’ peptides.
The skin of an adult human is a complex ecosystem spread over a 1.8 m2 area, including folds, invaginations and specific niches where the microbes’ living conditions can vary quite significantly. Most microorganisms living on the skin are harmless, and, in some cases, they can perform certain functions without involving the human genome.
A shift in our understanding of the skin, moving on from “the skin is the biggest bodily organ providing barrier function by its specific structure and cell functions” to “the skin is an ecosystem, a live biological complex of various microorganisms actively interacting with tissue cells” helps us achieve a more profound understanding of how the skin functions are performed and in the end allows us to discover new ways to prevent and treat various skin pathologies, including the ones that cause aesthetic discomfort.
External factors have a strong, and often negative, effect on the microbiome’s conditions and characteristics, reducing its diversity and richness and decreasing the skin’s protective function.
A number of studies confirm that various physical injuries, systemic and topical disease therapy, stress and psychological discomfort causing endocrine and metabolic changes in the body can also affect the skin’s microbiome and the pathogeny of certain microbes. In particular, UV radiation affects the characteristics of the microbiome due to UV rays’ well-documented bactericidal effect. People drinking alcohol excessively and developing addiction and deficiency conditions display changes in the skin microbiome associated with general health decline, immune disorders and imbalance in the skin’s stratum corneum.
Frequent washing disrupts the skin’s barrier function and brings about significant, and regarded as negative, changes to the microbiome, increasing the risk of infectious skin diseases and dermatoses.
There is abundant evidence pointing to the potential effect of hygiene solutions and skincare (including cleansers, moisturisers and even makeup) on the skin microbiome. It is entirely possible that any agents and impact affecting the epidermal protective barrier in this way or another can have similar effects.
By now, the importance of skin and body microbiomes has been firmly established by numerous studies. Evidently, the microbiome makes a vital contribution to both the immediate immune response and the formation of the immune system in general.
Many skin diseases are reliably associated with changes in the skin microbiome, and molecular analysis confirms significant differences between the microbiome of people with and without diseases. Moreover, the microbiome of patients with certain diseases shares undeniable similarities and characteristics for their particular pathology. In order to describe the microbiome imbalance, the term skin dysbiosis has been suggested, and it is diagnosed more and more, even in oncological skin pathology.
There is a shift in our understanding of skin cleansing, too. Bearing in mind that the skin’s functions are enabled by, apart from the tissue itself, a complex of mutually active cells and a live biological conglomerate of microorganisms, we are faced with a necessity to reconsider, on a conceptual level, our treatment of many a cell disease and condition. In effect, we are suggesting the possibility of correcting the skin’s condition by changing the microbiome and actively restoring the balance of microorganisms, which makes the skin healthy.
Key ingredients, being able to change the microbiome and helping to maintain its health and diversity, are prebiotics and probiotics. They are fairly common, both in professional and home-use cosmetic solutions. Initially, skincare with probiotics and prebiotics was offered to care for sensitive or damaged skin. However, numerous studies have shown that prebiotic and probiotic therapy can be universal and generally beneficial for the skin, even having an anti-age effect.
The study of the human microbiome, The Human Microbiome Project, changes not only the ways we care about skin and treat the diseases of the skin and gut, but our general view of the human body. In essence, a human’s body is not an individual organism but rather a complex of human cells and various microorganisms which can’t be separated and shouldn’t be regarded and studied on their own.
The number of microorganisms colonising a human body exceeds the number of human cells by about 10 times. Microorganisms make up from 1% to 3% of body mass, i.e. on average, a human weighing 100 kg carries about 2 kg of microorganisms. We have 360 times more protein-coding genes of microbial origin than our own human genes. It would appear that humans and microorganisms are inseparable, and it’s about time to find a way to cohabitate and benefit each other. Skin health depends on the skin’s microbiome health, and daily skincare should be the basis of the microbiome supporting maintaining skin functionality. Fresh and youthful looking skin is a bonus given to us by our microbiome, and the more we care about it, the better we can look.
