It’s one of the crueler realities of teendom — some kids are plagued with monster zits and problem skin, while others tend to sail through adolescence with nary a blemish.
Researchers may finally be able to explain why. Pimples, as skin experts have long known, are the result of infected and inflamed pores that are aggravated by bacteria. But not all bacteria residing in the skin are created equal, and some are more prone to causing breakouts than others.
In a study published in the Journal of Investigative Dermatology, researchers at the University of California, Los Angeles (UCLA) explored the world of the skin pore to get a deeper understanding of which species make these niches home and how they’re affected by stress and the environment. Previous studies suggested that one particular species, Propionibacterium acnes, was largely responsible for the pimples that erupt during adolescence; when researchers took samples of zits and cultured the microbial residents, P. acnes proved to be the most numerous. In addition, experiments in animals also showed that introducing P. acnes to the skin could trigger an immune response that resembled a breakout.
But when Huiying Li in UCLA’s department of molecular and medical pharmacology and her team compared the bacteria grown from people with problem skin to those grown from clear-skinned individuals, they were disappointed. It turns out that almost everybody harbors populations of P. acnes, and that the bacterium comprises 90% of the microbes that live in the pores. “We started out thinking that something other than the species we previously cultured would show up in clear-skinned people, but we didn’t find that,” says Li. “There was no difference in bacteria between the participants with acne and healthy-skinned people.”
She suspected that there might be differences in the strains of P. acnes habiting the different skin types, and took advantage of recent advances in gene sequencing to map out all the genes of the P. acnes strains isolated from the participants. The analysis revealed two strains of the bacterium that were associated with breakouts and one strain that was more dominant among the clear-skinned individuals. “So we are really excited because potentially there is a good guy that protects the skin from getting acne,” says Li. “That means there could be a simple cream or lotion with the good strain added that can stop pimples from developing before they even start.”
That would certainly be a welcome development for millions of teens, who often find only temporary relief from acne with current medications or skin treatments. Most of those, says Li, target and kill all P. acnes strains, including the ones that could be co-opted into thwarting breakouts. “Killing all of the strains doesn’t really help. But if you kill the bad ones and keep the good ones, you can hopefully restore the balance and keep skin in a healthy state.”
The results are only the latest that support work in the field of the microbiome, which investigates the hidden world of bacteria, viruses and other pathogens that live within us and play an important role in our health. Promising studies hint that the composition of bugs in our digestive system, for example, may dictate our tendency toward obesity, and that the bacteria in our gut and respiratory systems may influence the risk of allergies and asthma. “There is a lot of excitement about the microbiome,” says Li.
Populations of microbes can differ not only between people but also within a person. Learning to exploit and manipulate these invisible residents could open up new ways of treating chronic diseases — as well as acne.