Skip to content

Tag: skin microbiome

1

Published on 1 Comment on Microbes of the Skin

Recently I was asked about the human skin microbiome (skin microbial communities) and whether the things we do frequently (e.g. use soap and shampoo, go swimming in a pool) has an effect on our skin microbiome. As I've posted earlier, human skin microbes include bacteria, fungi, viruses, and  archaea. Most of these microbes are harmless or beneficial, but when the microbial communities are out of whack (dysbiosis), then there are diseases or skin disorders (such as acne, psoriasis, and eczema). The human skin acts as a physical barrier, a first line of defense, to pathogens (microbes that can cause disease). Studies have found that using soaps, lotions, make-up, our diet and lifestyle all have some effect on skin microbial communities. Even living with someone results in some microbial exchange. Spending more time outdoors, owning pets, and drinking less alcohol (or none) are all associated with higher levels of microbial skin diversity.

But then I came across a small study from 2016 (National Human Genome Research Institute, NIH, Bethesda, MD) in Cell - Temporal Stability of the Human Skin Microbiome. The researchers found that skin microbial communities are "surprisingly stable over time" (the study lasted 2 years), even though the humans were typically exposed to things daily that could disrupt their skin microbial communities (other people, clothing, the environments). But some individuals had more stable communities than others, and stability varied from site to site (the feet had the least stable microbial communities). Also, they found that bacterial, fungal, and viral communities not only show a strong preference for inhabiting specific skin sites, but also serve as "microbial fingerprints" that are highly unique to individuals. They did point out that "immunosuppression, illness, or the occurrence of disease have been shown to cause major shifts in skin communities".

Then there is a recent 2018 review article - but behind a paywall even though the researchers worked for NIH, thus paid for with our tax dollars (!!).They also discussed all the microbes living on the skin, and how when the microbial communities are out of whack (dysbiosis), then there is disease (whether acne, or eczema, etc.). Microbes that are beneficial in healthy people can become pathogenic, e.g. when the person has a disease. It also pointed out that only with modern genetic sequencing methods (rather than old style "cultures") can one really see what makes up the skin microbial communities. And that using these methods we can compare the skin microbes of healthy persons with those with a disease. And yes, there then is also the possibility of finding protective, beneficial microorganisms which are in healthy persons, but absent or under-represented in those with a disease. Sounds  like probiotics for the skin! ...continue reading "Microbes of the Skin"

Published on Leave a comment on Couples Living Together Share Skin Microbes

Did you know that you exchange some skin microbes with the person you live with? A recent study looked at the microbial communities on different regions of the skin of 10 heterosexual couples living together. The researchers found that cohabitation resulted in microbes being shared, but that a person's own microbes were more important, as well as their biological sex and what region of the skin was sampled. In other words - people's microbes look more like their own microbiome than that of their significant other.

Skin is the largest organ of the body, and it is a protective barrier between a person and its environment. The skin contains a diverse microbial community of largely beneficial and benign microorganisms, and also protects the body from microorganisms with the potential to cause disease. Studies show that at least one million microbes (bacteria, fungi, viruses, archaea, etc.) occupy each square centimeter of skin. Humans shed over one million biological particles per hour.

The researchers also found that female skin microbial communities were more diverse than that of males, and that spending more time outdoors, owning pets, and drinking less alcohol (or none) were all associated with higher levels of microbial skin diversity. They found that a person's biological sex could be determined 100% of the time from microbes on the inner thigh skin. The skin of the feet had the most matched microbes among couples - perhaps when they walk barefoot on floors and the shower, they are sharing microbes (from skin particles that had been shed). From Science Daily:

Not under the skin, but on it: Living together brings couples' microbiomes together

Couples who live together share many things: Bedrooms, bathrooms, food, and even bacteria. After analyzing skin microbiomes from cohabitating couples, microbial ecologists at the University of Waterloo, in Canada, found that people who live together significantly influence the microbial communities on each other's skin. The commonalities were strong enough that computer algorithms could identify cohabitating couples with 86 percent accuracy based on skin microbiomes alone, the researchers report this week in mSystems, an open-access journal of the American Society for Microbiology.

However, the researchers also reported that cohabitation is likely less influential on a person's microbial profile than other factors like biological sex and what part of the body is being studied. In addition, the microbial profile from a person's body usually looks more like their own microbiome than like that of their significant other. "You look like yourself more than you look like your partner," says Ashley Ross, who led the study while a graduate student in the lab of Josh Neufeld.

Neufeld and Ross, together with Andrew Doxey, analyzed 330 skin swabs collected from 17 sites on the participants, all of whom were heterosexual and lived in the Waterloo region. Participants self-collected samples with swabs, and sites included the upper eyelids, outer nostrils, inner nostrils, armpits, torso, back, navel, and palms of hands. Neufeld says the study is the first to identify regions of skin with the most similar microbiomes between partners. They found the strongest similarities on partners' feet. "In hindsight, it makes sense," says Neufeld. "You shower and walk on the same floor barefoot. This process likely serves as a form of microbial exchange with your partner, and also with your home itself." 

The analyses revealed stronger correlations in some sites than in others. For example, microbial communities on the inner thigh were more similar among people of the same biological sex than between cohabiting partners. Computer algorithms could differentiate between men and women with 100 percent accuracy by analyzing inner thigh samples alone, suggesting that a person's biological sex can be determined based on that region, but not others. The researchers also found that the microbial profiles of sites on a person's left side -- like hands, eyelids, armpits, or nostrils -- strongly resemble those on their right side. Of all the swab sites, the least microbial diversity was found on either side of the outer nose. [Original study.]

Published on Leave a comment on It Is Normal to Have Archaea On Our Skin

Something new to add to the list of what is in our skin microbiome - the community of microbes (bacteria, fungi, viruses) living on our skin. It turns out we also have archaea, which are single-celled microorganisms that are thought to be beneficial. (Earlier post on archaea found in our bodies.)

The human skin microbiome acts as a barrier protecting our body from pathogens and other environmental influences. The most common archaea found in the samples (from the chest area of 51 volunteers between the ages of 1 to 75 years) is called Thaumarchaeota. The results reveal that archaea are more abundant in people older than 60 years or younger than 12 years (as compared to middle-aged persons). But there were no differences between males and females. From Science Daily:

What's on your skin? Archaea, that's what

It turns out your skin is crawling with single-celled microorganisms -- and they're not just bacteria. A study by the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and the Medical University of Graz has found that the skin microbiome also contains archaea, a type of extreme-loving microbe, and that the amount of it varies with age. The researchers conducted both genetic and chemical analyses of samples collected from human volunteers ranging in age from 1 to 75. They found that archaea (pronounced ar-KEY-uh) were most abundant in subjects younger than 12 and older than 60. 

In addition to the influence of age, they found that gender was not a factor but that people with dry skin have more archaea. "Archaea might be important for the cleanup process under dry skin conditions," said Moissl-Eichinger. "The results of our genetic analysis (DNA-based quantitative PCR and next-generation sequencing), together with results obtained from infrared spectroscopy imaging, allowed us to link lower levels of sebum [the oily secretion of sebaceous glands] and thus reduced skin moisture with an increase of archaeal signatures."

It was not until the 1970s that scientists realized how different archaea were from bacteria, and they became a separate branch on the tree of life -- the three branches being Bacteria, Archaea, and Eukarya (which includes all plants and animals). Archaea are commonly found in extreme environments, such as hot springs and Antarctic ice. Nowadays it is known that archaea exist in sediments and in Earth's subsurface as well, but they have only recently been found in the human gut and linked with the human microbiome.

Their study focused on Thaumarchaeota, one of the many phyla of archaea, as little evidence of the others was found in the pilot study. "We know that Thaumarchaeota are supposed to be an ammonia-oxidizing microorganism, and ammonia is a major component of sweat, which means they might play a role in nitrogen turnover and skin health," Holman said. .... the team also correlated archaeal abundance with skin dryness, as middle-aged persons have higher sebum levels and thus moister skin than the elderly. So far, most archaea are known to be beneficial rather than harmful to human health. They may be important for reducing skin pH or keeping it at low levels, and lower pH is associated with lower susceptibility to infections.  [Original study.]

Thaumarchaeota archaea. These single-celled organisms have just one membrane sac that encloses their bodies. Credit: Univ. of Washington

 

Published on

For those who missed it. An amusing and informative personal story (Julia Scott) about trying to cultivate a healthy skin biome. Well worth reading. Excerpts from the May 22, 2014 NY Times:

My No-Soap, No-Shampoo, Bacteria-Rich Hygiene Experiment

For most of my life, if I’ve thought at all about the bacteria living on my skin, it has been while trying to scrub them away. But recently I spent four weeks rubbing them in. I was Subject 26 in testing a living bacterial skin tonic, developed by AOBiome, a biotech start-up in Cambridge, Mass. The tonic looks, feels and tastes like water, but each spray bottle of AO+ Refreshing Cosmetic Mist contains billions of cultivated Nitrosomonas eutropha, an ammonia-oxidizing bacteria (AOB) that is most commonly found in dirt and untreated water. AOBiome scientists hypothesize that it once lived happily on us too — before we started washing it away with soap and shampoo — acting as a built-in cleanser, deodorant, anti-inflammatory and immune booster by feeding on the ammonia in our sweat and converting it into nitrite and nitric oxide.

 Because the N. eutropha are alive, he said, they would need to be kept cold to remain stable. I would be required to mist my face, scalp and body with bacteria twice a day. I would be swabbed every week at a lab, and the samples would be analyzed to detect changes in my invisible microbial community.

While most microbiome studies have focused on the health implications of what’s found deep in the gut, companies like AOBiome are interested in how we can manipulate the hidden universe of organisms (bacteria, viruses and fungi) teeming throughout our glands, hair follicles and epidermis. They see long-term medical possibilities in the idea of adding skin bacteria instead of vanquishing them with antibacterials — the potential to change how we diagnose and treat serious skin ailments. 

For my part in the AO+ study, I wanted to see what the bacteria could do quickly, and I wanted to cut down on variables, so I decided to sacrifice my own soaps, shampoo and deodorant while participating. I was determined to grow a garden of my own. Some skin bacteria species double every 20 minutes; ammonia-oxidizing bacteria are much slower, doubling only every 10 hours. And now the bacteria were on my skin.

I had warned my friends and co-workers about my experiment, and while there were plenty of jokes — someone left a stick of deodorant on my desk; people started referring to me as “Teen Spirit” — when I pressed them to sniff me after a few soap-free days, no one could detect a difference. Aside from my increasingly greasy hair, the real changes were invisible. By the end of the week, Jamas was happy to see test results that showed the N. eutropha had begun to settle in, finding a friendly niche within my biome.

AOBiome is not the first company to try to leverage emerging discoveries about the skin microbiome into topical products. The skin-care aisle at my drugstore had a moisturizer with a “probiotic complex,” which contains an extract of Lactobacillus, species unknown. There is even a “frozen yogurt” body cleanser whose second ingredient is sodium lauryl sulfate, a potent detergent, so you can remove your healthy bacteria just as fast as you can grow them.

Although a few studies have shown that Lactobacillus may reduce symptoms of eczema when taken orally, it does not live on the skin with any abundance, making it “a curious place to start for a skin probiotic,” said Michael Fischbach, a microbiologist at the University of California, San Francisco. Extracts are not alive, so they won’t be colonizing anything.

It doesn’t help that the F.D.A. has no regulatory definition for “probiotic” and has never approved such a product for therapeutic use. “The skin microbiome is the wild frontier,” Fischbach told me. “We know very little about what goes wrong when things go wrong and whether fixing the bacterial community is going to fix any real problems.”

I asked AOBiome which of my products was the biggest threat to the “good” bacteria on my skin. The answer was equivocal: Sodium lauryl sulfate, the first ingredient in many shampoos, may be the deadliest to N. eutropha, but nearly all common liquid cleansers remove at least some of the bacteria. Antibacterial soaps are most likely the worst culprits, but even soaps made with only vegetable oils or animal fats strip the skin of AOB.