Our skin is literally covered in microbes forming the skin microbiota.  There is a huge potential for using safe microbes for treating infections, as natural alternatives to fight against antibiotic resistance, and as solutions in the rapidly expanding skincare market. The review ‘Protecting the outside: biological tools to manipulate the skin microbiota’ in FEMS Microbiology Ecology emphasizes the role microbes play in maintaining a healthy skin. This blog by Dr Julie O’Sullivan presents tools and strategies available to scientists to manipulate the human skin microbiota for health improvement purposes. #FascinatingMicrobes

A skin seesaw

Our skin is our first line of defence against the outside world, with our skin microbiota forming an important part of this defence barrier. Our review article in FEMS Microbiology Ecology looks at the biological ‘weapons’ produced by commensal microbes on the skin that can prevent and treat skin disease and infection. Ultimately, each individual has a unique microbiota composition and its balance is vital for an effective physical barrier.

Skin microbes do not normally cause skin infections but can be associated with skin flare ups. Instead, many recent studies have demonstrated that imbalances in skin microbiota can result in a number of diseases or infections, and that reintroducing bacteria normally present in abundance to skin lacking these can restore imbalances and alleviate some symptoms of disease.

Biological tools to balance the skin seesaw

Biological tools have the power to manipulate the skin microbiota either directly or indirectly, including bacteriocins, phage therapy, antibiotics, probiotics, and prebiotics. Our skin microbes produce bacteriocins, which are antimicrobial peptides that can improve skin health when topically applied. Staphylococci are among the most abundant bacteria on the human skin and many are known to produce bacteriocins, some of which kill MRSA (multi-resistant Staphylococcus aureus). These bacteriocins are potent inhibitors with either broad or narrow spectrum of activity.

Biological tools have the power to manipulate the skin microbiota either directly or indirectly, including bacteriocins, phage therapy, antibiotics, probiotics, and prebiotics.

Topical application of phage cocktails has been shown to accelerate the recovery process of skin infections. Probiotics have also been shown to be effective: in a study, pregnant women with family history of skin disorders ingested a probiotic cocktail (no hangover were ever reported) which protected against the occurrence of eczema in their infants.

Probiotics can induce a ‘glow of health’ in mice. Feeding a probiotic yogurt containing Lactobacillus reuteri to aged mice initiates an interleukin-10 dependent mechanism resulting in an improvement in their dermal thickness and fur appearance. A probiotic combination of Lactobacillus rhamnosus and L. reuteri improved in the symptoms of eczema in children. Topical application of a prebiotic spray to skin lesioned by acne significantly improves skin health.

The gut-skin axis

While the gut-brain axis is a hot topic of research, much less is known about the gut-skin or skin-brain axes. In the 1930’s a theory of a gut-skin axis was put forward by Stokes and Pillsbury. Studies have since shown that the gut is like a “second brain’’ in that it has its own neuronal patterns and can function independently to the brain.

Is the gut the central processing unit of our bodies?  While the composition of a baby’s gut microbiota depends on what microbes first colonise the skin at birth (for example, C-section babies have increased Firmicutes and less Actinobacteria and have less stable skin microbiome when compared to naturally-delivered infants, though these differences seem to diminish after 24 weeks), intake of probiotics can cause reduction in skin inflammation and restoration of homeostasis of the skin microbiota .

While the gut-brain axis is a hot topic of research, much less is known about the gut-skin or skin-brain axes.

All of the organs in our bodies are linked in one way or another. We need to further identify and investigate the gut’s mechanisms of communication to the skin and other organs and explore if these can be manipulated to alleviate symptoms of skin infections. There is huge potential for further exploration of the gut-skin axis. Stokes and Pillsbury were well ahead of the game!

Normally we think that microbes on our skin mean that we are unhygienic, but in fact having the right microbes in the right balance is essential for skin health.  It is time to work together with our microbial partners to restore skin health.

About the author of this blog

Julie O’Sullivan (@julie_sile) is a postdoctoral researcher with APC Microbiome Ireland at University College Cork in the research group Microbes to Molecules. She recently completed her Ph.D, also with the APC, in Moorepark Food Research Centre, Fermoy, Co. Cork under Prof. Paul Ross, Dr. Mary Rea and Prof. Colin Hill. Her Ph.D research has focused on mining the human skin microbiota for much needed alternatives to antibiotics, primarily antimicrobial peptides called bacteriocins, that exhibit health potential against a wide range of pathogens, including skin pathogens. She is now continuing her research in this area to further explore the gut-skin connection.

About this blog

The section #FascinatingMicrobes for the #FEMSmicroBlog explains the science behind a paper, highlights the significance and broader context of recent findings, and present a digest of hot topics in microbiology. One of the main goals is to share the fascinating spectrum of microbes across all fields of microbiology.

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