Last updated March 8, 2018 at 8:41 am
The bigger the city, the less skin microbiome diversity – and that means more diseases.
Scientists collected microbiome samples from the cheeks of 231 healthy women between the ages of 25 and 35 living in three large cities (Kumning, Xi’an and Hohhot) and two megacities (Beijing and Guangzhou).
The subjects couldn’t be taking prescribed skin disease medication, nor could they wear makeup or wash their face in the 24 hours before they gave their sample.
The selected cities were at least 409 kilometres apart, with different climates and air quality, and the research subjects had lived in their city for at least five years.
The team then extracted and amplified the DNA from the samples to analyse the differences between the type and amount of species. They created networks that showed how the microbial communities formed in megacities compared to non-mega, smaller cities.
They found that skin microbiomes in megacities were more fragile as they had a lower network density. Meanwhile, the microbiome networks in smaller cities were more complex.
Previous studies have shown that as the severity of atopic dermatitis increased, the diversity of the skin microbiome decreased.
They also wanted to determine whether the microbial communities developed through a niche-based process rather than a neutral, random process. A niche-based process “assumes that different species occupy different niches dictated by local environmental filtering or interspecific competition,” as the authors explain in the paper. They found that environmental filtering was one of the biggest drivers, regardless of the size of the city. The microbiomes in megacities fit the niche-based process more than smaller cities.
Microbiome knowledge is booming
When it comes to our microbiomes, science is investigating with ever more seriousness, particularly when it comes to our guts. We’re learning more and more about how it affects our overall health, and figuring out ways to optimise it not only for nutrition but medicine as well.
Studies like this, however, show that when it comes to our skin microbiome we are playing catch-up. Our skin is our largest organ and serves an invaluable protective function.
The researchers suggest that understanding the skin microbiome in this way could lead to better perspectives on treating skin conditions like infectious diseases and chronic inflammatory disorders. There is potential to develop medicines designed to manipulate the microbiome known as pharmabiotics.
This research was published in Science Advances.