The research, led by a San Diego scientist, may lead to treatments that replace antibiotics, which are commonly used to treat rosacea. Although rosacea is not caused by bacteria, some antibiotics can reduce its symptoms.Physicians don't like to use the drugs because they may create more bacterial resistance.
The report was published recently in the journal Nature Medicine. It comes from Dr. Richard Gallo, chief of dermatology at University of California San Diego, and several colleagues at UCSD, the VA San Diego Healthcare System and institutions in Japan and France.
Their work moves scientists a step closer to revealing the root cause of rosacea, or at least what provokes it to become noticeable. Gallo described it as a one-two punch from two proteins - a peptide and an enzyme. The two work together to produce a third protein that disfigures the skin, he said.
Gallo called it "a trifecta of unfortunate factors in people with rosacea, like having lots of gasoline ... and a match."
Rosacea affects 14 million people in the United States, most of them of northern European descent. Spicy foods, heat and alcohol might worsen its symptoms.
A major problem is that the condition gives noses, cheeks and chins a splotchy redness and an overgrowth of tissue that can be mistaken as stemming from substance abuse or other health issues.
"Psychologically, there are some people who are really devastated by it," Gallo said. "Not only do they look terrible, some people think they're alcoholics."
The Gallo team's finding is important partly because it gives an explanation for why rosacea turns from mild to worse, said Dr. Jonathan Wilkin, chairman of the medical advisory board for the National Rosacea Society, which funded some of the research.
The three-protein process is "unlikely the primary cause, but it may offer targets for pharmacologists and drug developers to work with," said Wilkin, a dermatologist in Ohio.
For their study, Gallo and his colleagues took samples of skin from 20 patients with chronic rosacea in an area near the nose. They compared them with similar samples from 20 people who did not have rosacea.
The researchers found that skin harbors a peptide called cathelicidin, which normally protects it against infections. People with rosacea have too much cathelicidin, causing an interaction that harms their skin instead.
"All 20 of these patients had far more peptides than normal," Gallo said.
Those with rosacea also had greatly elevated levels of an enzyme called stratum corneum tryptic enzyme, or SCTE. The enzyme is what turns abundant amounts of cathelicidin from a protective agent into a harmful one.
To further test their theory, the researchers injected mice with cathelicidin peptides found in patients with rosacea and added SCTE. This combination caused the mice to have a blotchy red appearance.
© Copley News Service