The microbiome is defined as the population of bacteria and other microorganisms living in a particular environment – be it a hot spring at Yellowstone, a ripe French cheese or even human skin. New techniques for studying microbial populations have opened up a whole world of organisms which were previously invisible because they would not grow in the laboratory. Some of these organisms may turn out to be important in human health and disease; of course many “harmful” organisms are known, but perhaps just as important are the beneficial organisms which keep things in a healthy balance.
A recent paper is a good example of what we are starting to learn and also of the work that still needs to be done.
Many of us have suffered from eczema, especially in childhood, or knows someone else who has. In fact it affects 1 in 5 children and 1 in 12 adults [National Eczema Society]. Eczema is technically known as atopic dermatitis, and causes itching, soreness and dry, scaly skin. Its causes appear to be complex, and can include allergies and genetic factors. A recent paper from Chng et al.  (reviewed in ) describes experiments into the role of microbes in eczema.
One of the characteristics of eczema is that sufferers have “flares” when symptoms worsen, and periods where symptoms improve. Chng et al. compared the skin microbiomes of eczema sufferers between flares, during flares, and those of healthy controls. They found a different mix of bacteria in each case. It has been known for many years that there is an association between the bacterium Staphylococcus aureus and skin flares in eczema, but only with modern “metagenomic” approaches is it possible to look at the whole population of bacteria and investigate how they are interacting. What’s more, metagenomics shows not just what species are present but what their genetic make-up is, which can give insights into their metabolism and interactions.
The metagenomics revealed the expected increase in S. aureus but also showed an increase in a variety of other species that may be able to inhibit its growth. What is perhaps not clear yet is the relationship between cause and effect; what triggers the changes in the microbial populations during a flare? A lot more work will be needed to untangle these relationships. Excitingly, however, a recent paper  suggests that adding back some of these helpful species in a skin cream may be beneficial.
This study provides a great example of how many interacting factors play a role in health and disease. Understanding and measuring multiple factors in this way is an approach we at Holistx are dedicated to pursuing.
[Photo credit: “Kateryna Kon/Shutterstock.com”]