From our mid-20s onwards, our skin progressively loses its elasticity and plumpness, leading to wrinkles and sagging. Why this occurs isn鈥檛 entirely understood. However, new research suggests that the microorganisms that reside on our faces may be involved.
A protein called collagen acts as a scaffold for our skin, giving youthful skin a smooth appearance, but the quantity and quality of our collagen production declines with age.
at the Jackson Laboratory in Connecticut and her colleagues wondered whether the skin microbiome 鈥� a variety of organisms including bacteria, fungi and viruses that live and interact with each other 鈥� could be involved in the loss of collagen.
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鈥淲e were interested in examining to what degree the skin microbiome differed in ageing skin, because we鈥檝e found previously that it is the manifestation of genetic and environmental factors, including lifestyle, ethnicity, geographic residence, sun exposure, skin characteristics, hygiene habits, overall health and age,鈥� says Oh.
To learn more, the researchers took swabs from the external cheeks of 51 white women living in Paris, France. Of these volunteers, 26 were aged between 20 and 26, with the remainder aged between 54 and 60.
The team analysed the swabs using a technique known as shotgun metagenomics. This involves identifying nucleotide sequences 鈥� the building blocks of DNA 鈥� in the swabs and mapping them against a general database of microbes and their corresponding nucleotides to gauge the bacterial species present on the volunteers鈥� cheeks.
Oh and her colleagues found that strains of the bacterial species聽Cutibacterium acnes 补苍诲听Staphylococcus epidermidis were associated with a decline in collagen levels, measured via infrared light, among the volunteers aged 54 to 60.
Previous research suggests that certain strains of these two species can drive inflammation in the skin, which may also be involved in the physical signs of ageing, says Oh. For example, C. acnes is found in sebum, the natural oil that keeps skin moisturised. Excess sebum levels are associated with inflammation.
at the University of Bradford, UK, says that if further evidence supports the role of certain bacterial strains in driving physical skin changes, these species could one day be targeted in anti-ageing treatments. However, it is currently unclear whether these bacteria cause a loss of collagen or if a loss of collagen is what changes the skin microbiome.
鈥淚s it chicken or egg?鈥� says Thornton. 鈥淭o answer that, we need more molecular studies where you put cells from different layers of the skin and different microbiomes together in controlled experiments to see what is happening.鈥�
The researchers also found that the skin microbiomes of the older participants were made up of a greater proportion of bacteria with antimicrobial-resistant genes, compared with the microbiomes of the younger volunteers.
According to Oh, we don鈥檛 know whether the presence of certain antibiotic-resistant bacteria on our skin affects the physical signs of ageing. However, she believes it is plausible that they could play some role.
鈥淎s we age, we鈥檝e cumulatively been exposed to many antibiotics, and microbes can acquire antibiotic resistance genes from the environment and each other, and these can be maintained in the cumulative gene pool of our skin microbes,鈥� she says. 鈥淔or sure, antibiotic use can change microbiome characteristics, which in turn can have immune and skin barrier effects.鈥�
Oh adds that the latest study should serve as a starting point for further research, rather than imminently influencing the development of new anti-ageing treatments.
鈥淭hese association studies try聽to聽pinpoint weak links in our聽skin microbiome-skin interactions that can then be tested mechanistically,鈥� she says.聽鈥淭he next step would be聽to聽examine how the skin microbiome might directly influence collagen production.鈥�
Future studies should also examine the skin microbiomes of individuals of a range of ages, within a larger group of people of different ethnicities, says Oh. They should also sample the skin microbiome on more areas of the face, not just the cheeks, she says.
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