A New Front in the Fight Against Rosacea
About 14 million Americans are afflicted with rosacea, a chronic inflammatory condition sometimes referred to as "adult acne." Most frequently affecting people ages 30 to 60, rosacea can cause pimples, visibly enlarged blood vessels in the face, chronic eye irritation, tough and thickened skin, and, in severe cases, rhinophyma—a swollen, bulbous nose that was famously manifest in actor W. C. Fields. Though treatments, including oral and topical antibiotics and laser therapies, can ameliorate symptoms, there is no cure. But a study published Sunday in the online edition of Nature Medicine points the way to potentially better therapy. We spoke with its author, dermatologist Richard Gallo of the University of California-San Diego.
Why do some people develop rosacea?
Many different things can contribute to rosacea. One is your genetic makeup. We believe that if you don't have the genetic predisposition for rosacea, you will not get it. Another factor is environment—things that cause your face to flush, like spicy food, or heat, or alcohol, or things that live on your skin, like bacteria and small mites. These can trigger [symptoms of] rosacea.
What idea led to your new finding?
My laboratory has an interest in what's known as innate immunity. When you're born, you have an innate immune system that has the ability to recognize different types of danger and, among other things, produce antimicrobial peptides as a defense. We had been studying [antimicrobial peptides] in human skin and noticed that in some cases they caused problems in cells that looked like elements of rosacea. We hypothesized that patients with rosacea might have abnormal antimicrobial peptides.
What have we learned about these peptides?
These molecules are made by every living organism. In humans, they are natural antibiotics. Many of them not only kill bacteria but also act as antifungal and antiviral molecules. They inhibit many different types of bacteria and help control the normal growth of bacteria on your skin and in many parts of your body.
But if antimicrobial peptides usually fight disease, how can they cause problems?
In rosacea, they are made abnormally. One hundred percent of the rosacea patients we looked at made more antimicrobial peptides than normal. And the peptides were processed into an abnormal form that we found only in rosacea patients' skin, not in normal skin. This abnormal form triggers the body's inflammatory immune system, which normally [activates] when you have a cut or an injury. But the problem with rosacea patients is that this inflammatory response never stops. It can go on to cause pimples and enlarged blood vessels and, over time, may eventually lead to some of the later symptoms of rosacea, like rhinophyma.
How might your discovery improve the treatment of rosacea?
One of the most common ways to treat rosacea has been with antibiotics. But the findings we have now will allow us to go after the disease's triggering mechanism—the peptide—rather than trying to kill bacteria, which can be part of the disease but are not the sole cause. In the future, a patient with the first signs of the disease might receive a drug that he or she could apply to the skin daily, inhibiting the production of abnormal antimicrobial peptides. Prime candidates include drugs that inhibit the enzyme that makes this bad form of peptide. There are multiple [such] drugs, which we can now test for efficacy in treatment of the disease.