Study unlocks genetic code of acne germ

Pimples: New information might lead to more effective treatments for the bane of adolescents, and some adults.

Medicine & Science

August 09, 2004|By Jonathan Bor | Jonathan Bor,SUN STAFF

Eager to combat life-threatening diseases from cancer to cholera, scientists have unraveled the genetic blueprints of some of the nastiest bugs that plague the human race.

Now German researchers say they have the genetic code of a microbe that won't kill anybody but contributes to one of the great torments of adolescence.

Reporting in the journal Science, the researchers describe the genome of the bacterium, Propionibacterium acnes. Not always an evildoer, the bug sits on the surface of everyone's skin. The trouble develops in the blocked pores that are the beginnings of acne pimples.

The bacteria can turn a pimple into the red, swollen and sometimes painful lesions that are a source of embarrassment - even shame - for youngsters traversing the social terrain of adolescence.

Acne afflicts an estimated 17 million Americans, including many adults.

Soap and chocolate

Contrary to popular belief, hygiene and diet have little to do with the condition, doctors say.

Though treatments have made acne less onerous than it was a generation ago, scientists hope that the genetic blueprint could lead to better drugs with fewer side effects.

In theory, such drugs could target specific actions of the bacteria, which work in different ways to inflame the skin.

"We have got the tool in hand," said Holger Bruggemann, the lead author of the report. "Now we have the chance to find good targets."

Bruggemann, a microbiologist at the Pasteur Institute in Paris, directed the research while at the Institute of Microbiology and Genetics in Gottingen. Colleagues there and at the University of Ulm, also in Germany, participated.

In some ways, their work underscores the complexity of a common skin condition that often must be fought on several fronts at once. Some dermatologists reviewing the report said any new therapy, however effective, would probably be one weapon among many.

"This allows us a window to look at certain therapies that would be more specific," said Dr. Patrick McElgunn, assistant professor of dermatology at the Johns Hopkins School of Medicine. "But acne is like everything else in life. It's multi-factorial."

Acne begins when hair follicles become blocked with excess skin cells. Oil produced by sebaceous glands within the skin cannot flow to the surface and instead backs up within the follicle. As the oil collects, it produces a swollen pocket that is the basis of a pimple.

Under normal circumstances, the P.acnes bacteria live harmlessly on the skin. But trapped inside the follicle, they break down the oil (known as sebum) into harmful components that inflame the skin, making it red, swollen and sometimes warm to the touch.

In mild cases, acne can produce simple whiteheads or blackheads that eventually heal without a trace. Once inflamed, the lesions produce more unsightly blemishes that can leave disfiguring scars.

"If you didn't have P.acnes, you wouldn't have all that inflammation and all that scarring," said Dr. Lynda Kauls, assistant professor of dermatology at the University of Maryland School of Medicine.

Several approaches

Current treatments attack various aspects of the disease, she said.

Medications known as retinoids work by reducing the obstruction of hair follicles. A powerful retinoid known as Accutane also reduces sebum production and inflammation.

Lotions containing benzoyl peroxide dry the skin and increase the shedding of skin cells, a healthy process that prevents the overgrowth of cells that can block pores. Antibiotics, another option, destroy bacteria and reduce inflammation.

In deciphering the genetic blueprint of P.acnes, the German scientists identified particular genes - and proteins produced by the genes - that play different roles in severe cases.

The blueprint, for instance, should help scientists understand how the bacteria break down oil and pull nutrients from the surface that enable the bacteria to flourish, experts said. It also identifies the bacterial proteins that cause the immune system to flare up.

Kauls said she was skeptical that the information would lead to new treatments anytime soon, though she didn't rule out benefits in the long term.

"I don't know that anyone would go out and design medications based on any of these findings, mostly because there are a lot of good treatments."

Fewer side effects

Though he didn't predict any early success, McElgunn said the findings could lead to "biologics" - treatments made possible by genetic discoveries that block specific parts of a microbe's activity.

"By understanding more and more the products of genes, you can direct more specific therapy," he said. "You end up with drugs that have less side effects and are more direct."

Lydia Preston, author of the new book Breaking Out, said many people regard acne as a purely cosmetic condition and underestimate its psychological impact.

"It made me feel tremendously subconscious," said Preston, who had acne from her teens into her 30s and was left with scars.

"I could never meet anyone without thinking what are they thinking about me based on my skin. It only intensified in adulthood. As a teenager, you really assume you're going to outgrow this. When you don't, it's pretty devastating."

Like obesity, she said, acne carries a social stigma. When people see someone with serious acne, they assume that the person doesn't wash or eat properly.

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