The bacteria that cause acne live on everyone's skin, yet one in five people is lucky enough to develop only an occasional pimple over a lifetime. What's the secret?
In a boon for teenagers everywhere, scientists at Washington University School of Medicine in St. Louis, the University of California at Los Angeles and the Los Angeles Biomedical Research Institute have discovered there are "bad" strains of acne bacteria associated with pimples and "good" strains that may protect the skin.
Their findings, published Feb. 28 in the Journal of Investigative Dermatology
, could lead to new therapies to prevent and treat the disfiguring skin disorder.
"We learned that not all acne bacteria trigger pimples — one strain may help keep skin healthy," says lead author Huiying Li, PhD, an assistant professor of molecular and medical pharmacology at the David Geffen School of Medicine at UCLA. "We hope to apply our findings to develop new strategies that stop blemishes before they start and enable dermatologists to customize treatment to each patient's unique cocktail of skin bacteria."
The scientists looked at a tiny microbe with a big name: Propionibacterium acnes, a type of bacteria that thrives in the oily depths of our pores. When the bacteria aggravate the immune system, they cause the swollen, red bumps associated with acne.
Using over-the-counter pore-cleansing strips, LA BioMed and UCLA researchers lifted P. acnes bacteria from the noses of 49 pimply and 52 clear-skinned volunteers. After extracting the microbial DNA from the strips, the scientists tracked a genetic marker to identify the
bacterial strains in each volunteer's pores and recorded whether the person suffered from acne.
Washington University scientists sequenced the genomes of 66 of the P. acnes strains, enabling the team to zero in on genes unique to each strain.
"Our research underscores the importance of
strain-level analysis of the world of human microbes to define the role
of bacteria in health and disease," says co-author George Weinstock, PhD, associate director of The Genome Institute and professor of genetics at
Washington University in St. Louis. "This type of analysis has a much
higher resolution than prior studies that relied on bacterial cultures
or only made distinctions between bacterial species."
The researchers wanted to learn whether the bacterial strains looked notably different when they were taken from diseased skin, compared with healthy skin.
"Two unique strains of P. acnes appeared in one out of five volunteers with acne but rarely occurred in clear-skinned people," says co-author Noah Craft, MD, a dermatologist and
director of the Center for Immunotherapeutics Research at LA BioMed at
Harbor-UCLA Medical Center.
The biggest discovery was still to come.
"We were extremely excited to uncover a third strain of P. acnes that's common in healthy skin yet rarely found when acne is present," says Li. "We suspect that this strain contains a natural defense mechanism that enables it to recognize attackers and destroy them before they infect the bacterial cell."
Offering new hope to acne sufferers, the researchers believe that increasing the body's friendly strain of P. acnes through the use of a simple cream or lotion may help calm spotty complexions.
"This P. acnes strain may protect the skin, much like yogurt's live bacteria help defend the gut from harmful bugs," Li says. "Our next step will be to investigate whether a probiotic cream can block bad bacteria from invading the skin and prevent pimples before they start."
Additional studies will focus on exploring new drugs that kill bad strains of P. acnes while preserving the good ones; the use of viruses to kill acne-related bacteria; and a simple skin test to predict whether a person will develop aggressive acne in the future.
Acne affects 80 percent of Americans at some point in their lives, yet scientists know little about what causes the disorder and have made limited progress in developing new strategies for treating it. Dermatologists' arsenal of anti-acne tools — benzoyl peroxide, antibiotics and Accutane (isotretinoin) — hasn't expanded in decades. Most severe cases of acne don't respond to antibiotics, and Accutane can produce serious side effects.
The research was supported by the National Institutes of Health (NIH) and the National Institute of Arthritis and Musculoskeletal and Skin Diseases (
UH2AR057503 and U54HG004968).
Elashoff D, Erfe MC, Loncaric A, Kim J, Modlin RL, Miller JF, Sodergren E, Craft N, Weinstock GM, Li H. Propionibacterium acnes
strain populations in the human skin microbiome associated with acne. Journal of Investigative Dermatology
. Feb. 28, 2013.