The skin microbiome consists of bacteria, viruses, fungi and mites that inhabit its surface. If they are in a quantitative and species balance, they protect the skin, thanks to which, for example, atopic dermatitis, allergies, dandruff and other skin diseases do not appear. What influences the skin microbiome?

The skin is the largest human organ that protects the body against harmful pathogens. This protection is also helped by microorganisms which, while living in balance, protect it against the appearance of symptoms that cause discomfort and, consequently, skin diseases.

The correct microbiome of the skin guarantees its he alth and nice appearance, so it is not worth getting rid of microorganisms through, among others, frequent use of cosmetic procedures or aggressive care preparations. Find out what the skin microbiome functions, what affects it, and how to take care of it.

The skin microbiome - what is it?

The skin microbiome is a complex ecosystem consisting of microorganisms that inhabit its surface. The term "microbiome" became popular when Joshua Lederberg won the Nobel Prize in 2001, and in his research he defined it as a collection of genomes of all microbes inhabiting the human body, i.e. bacteria, fungi, viruses and mites.

In turn the so-called skin microbiota is a collection of microorganisms understood as cells. It is worth realizing that the surrounding environment is full of various microorganisms that easily transfer from there to the skin.

Thus, the skin is colonized not only by beneficial and neutral microorganisms that live in symbiosis with skin cells, but also by less desired ones - pathogens.

As reported by the researchers from the Medical University of Silesia in Katowice in the "Dermatological Review" in 2015, the skin microbiome consists mainly of four types of bacteria: Actinobacteria, Firmicutes, Bacteroidetes and proteobacterai, Mallassezia fungi and mites from the group Demodex.

Sometimes it is also inhabited by pathogens, including staphylococcus aureus and streptococci, which in turn can cause infections and thus lead to the development of various skin diseases.

It is worth emphasizing, however, that the skin microbiome is individual for every person. Research by P.Kowalczyk, K. Głowacka and E. Górska, published in "Medycyna Rodzinna" in 2015, proved that only 13% of microorganisms obtained from the surface of the hand are identical in two individuals.

This proves that the skin is very diverse in terms of the microorganisms that live on it. Moreover, it is worth knowing that both the species and quantitative composition depend, among others, on from individual areas of the skin, its thickness, as well as humidity and temperature.

The skin microbiome - what are its functions?

The skin is the largest organ of the human body, the task of which is to integrate with the external environment, as well as protect against pathogens that want to penetrate inside the body.

Although the skin microbiome is in constant contact with microorganisms in the environment, thanks to its structure, including dry, rough and often flaky surface, not friendly to pathogen growth.

The skin does not accept any microorganisms it comes into contact with and thus protects the body against the formation of abnormal microflora.

It also includes substances that protect it against pathogens (e.g. tallow containing triglycerides), and which not only hinder the entry of unfavorable microorganisms, but also activate mechanisms of the immune system that effectively fight the threat.

Unfortunately, poor skin condition may be detrimental to the body and affect the growth of pathogenic bacteria. Infections occur mainly due to low immunity, when a person is receiving antibiotic therapy, or when the skin has wounds or foreign bodies (e.g. artificial valves).

The skin microbiome - what does it depend on and what affects it?

The skin microbiome depends on many factors, including on the thickness of the skin - other microorganisms will colonize the flat surfaces of the skin, and other skin folds and cavities. In addition to their different structure, these places also differ in temperature and humidity, which also affects the composition of the microbiome.

Therefore, the sebum-rich neck, face and head contain, among others, fungi of the genus Mallassezia, Actinobacteria and Firmicutes. On the other hand, moist places, i.e. feet, armpits and in the genital area, are colonized only by Actinobacteria and Firmicutes, and in areas predominant on the skin, referred to as dry, additionally Bacteroidetes and Proteobacteria appear.

The composition of the microbiome also depends on the pH of the skin (usually it is moderately acidic, 4-4.5), exposure to UV radiation and lifestyle.

Therefore, the composition of the skin microbiome is not only influenced by whatwe eat every day, but also what the daily skin care looks like, whether regular physical activity is performed and stimulants are used. The number and variety of microorganisms colonizing the skin also depends on the drugs used, stress, and also varies with age (e.g. in seniors whose skin is dry, the microbiome is less diverse).

Moreover, the skin microbiome is different for women and men - it is largely dependent on hormones and specific periods in life, e.g. pregnancy or menopause in women or puberty in both sexes. This also applies to differences within ethnic groups, life in different continents, in a different climate, and in industrialized or non-industrialized countries.

IMPORTANT! The skin microbiome is inhabited by microorganisms at the time of birth. In women giving birth by force of nature, the baby receives the microflora of the birth canal, while in women giving birth by caesarean section, it receives the microflora of the mother's skin.

In the youngest, the skin is inhabited mainly by bacteria and fungi. It is worth emphasizing, however, that around the age of 3, babies have the most microbes on their skin, which is related to, inter alia, with development and physiological changes.

As reported by researchers Y. Belkaid and T. Hand in 2012, the composition of the microbiome also depends on genetic predisposition and metabolic diseases. This is because they change the properties of the epidermis, which influences what the skin microbiome looks like in a particular person.

In addition, it also translates into the functioning of the immune system, which is then not able to protect the body against allergies and autoimmune skin diseases.

In addition, the composition of the microbiome is also influenced by temporary infections and diseases such as influenza, which cause the number and species of microorganisms on the skin to change, but after a cure, they return to their previous composition.

The skin microbiome and diseases

Normal skin microbiome is balanced both in terms of the species colonized on it and in numbers. Unfortunately, the imbalance, i.e. dysbiosis means that the skin does not constitute such a strong protective barrier, which in turn increases the risk of skin diseases.

The entry of pathogens living on the skin into the body may cause symptoms that cause discomfort, as well as serious diseases, including skin diseases such as atopic dermatitis (AD) and civilization diseases such as diabetes.

And so, if the skin is dry, it will be colonized by, for example, staphylococci, which infect people suffering fromfor atopic dermatitis (AD). Research by S. Seite and colleagues from 2014 proved that the microbiome of AD patients and he althy people differs - in the first group, the presence of pathogenic bacteria Staphylococcus spp. Is found, as well as a general lower diversity of the microbiome.

In turn, scientists from the University of Ioannina Medical School in 2012 published in "Clin Microbiol Rev." research proving that the most common fungi on the skin, i.e. those from the Malassezia group, stimulate the production of pro-inflammatory cytokines.

These, in turn, intensify skin symptoms in patients suffering from, among others for atopic dermatitis, psoriasis, seborrheic dermatitis and other dermatitis, inflammatory diseases. Fungi are also responsible for the formation of, for example, dandruff, and demodicosis, which belongs to the mite group, may cause erythema on the skin and, consequently, also rosacea.

The skin microbiome - how to care?

As emphasized by Dr. Robynnr Chutkan, author of the book "Good Bacteria", you should pay attention to cosmetics and skin treatments, as many of them can disturb the balance of the microbiome.

The point is that the substances they contain (mainly alcohol and antibacterial substances) remove the necessary bacteria and other microorganisms from the skin surface, which in turn leads to dysbiosis.

Thus, although initially the skin becomes only less elastic and dry, with time serious skin diseases may also appear. It is worth emphasizing that even water can be detrimental to the skin, so it is not worth washing your face, e.g. several times a day, because its alkaline reaction may cause an overgrowth of pathogens.

In order to properly care for the skin microbiome, use cosmetics without preservatives, dyes and fragrances, mainly with simple ingredients.

The rare use of antibiotics, for example, often used to treat conditions such as acne, will also be beneficial for the skin.

Applying them externally irretrievably changes the composition of the microbiome, which later may be difficult to rebuild. It is therefore worth considering all options, including less invasive ones, before deciding on a specific type of treatment and specific measures.

In order for the skin microbiome to be diverse, it is also worth using probiotics. They are most often used to maintain the balance of the intestinal microbiome, but it should be remembered that some cosmetics are enriched with prebiotics, which are an excellent breeding ground for bacteria.

About the authorSonia Młodzianowska Journalist, editor, copywriter. He publishes in he alth and parenting magazines and portals. Belongsto the Journalists for He alth Association.

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Category:

Dermatology