RosaceaNet Spotlight Article
What Causes Rosacea?
Research May Offer New Clues

What really causes rosacea? The answer is that no one knows. But researchers working at labs in San Diego and New York City may have found some important clues that could help solve this mystery.

The first key finding came when a team of researchers led by a dermatologist from San Diego discovered that cathelicidin, a protein that naturally occurs in the body, could cause the redness of rosacea. Cathelicidin normally protects the skin from infection.

The next step was to learn why cathelicidin causes redness in people with rosacea. To find out, the researchers took skin samples from 11 people with rosacea and 10 people who did not have rosacea. In the skin of every person with rosacea, they found an excessive amount of cathelicidin. They also found an abundance of the molecule that converts cathelicidin from inactive to active. None of the people without rosacea had these excessive amounts.

To find out if these high levels could induce rosacea, the team produced these excessively high levels in mice. In each case, the mice that had the high levels showed signs of rosacea on their skin — redness, visible blood vessels, bumps, and pimple-like lesions.

These findings led the researchers to conclude that the way the body processes cathelicidin determines whether it defends the skin against infection or causes inflammation.

A separate team of researchers has been working on the role that another chemical may play in rosacea. This team, lead by a dermatologist from New York City, discovered that adenosine triphosphate (ATP) may play a role in rosacea. ATP is released by the nervous system. It appears that stress, a common rosacea trigger, may activate the nervous system to release ATP. The researchers found that when the nerves of people with rosacea release ATP into the skin, a series of unique chemical events occurs. These events eventually lead to the bumps and pus-filled lesions of rosacea.

What this Research Means to People Living with Rosacea
While the cause remains a mystery, this research suggests that patients who have bumps, pus-filled lesions, and redness may not need long-term treatment with an antibiotic to control their rosacea. If inflammation causes these signs of rosacea, then treatment that effectively controls inflammation should be effective.

The data collected during the clinical trials that looked at the effectiveness and safety of non-antibiotic dosage doxycycline further supports this finding. During these clinical trials, the non-antibiotic dosage of doxycycline (also known as the anti-inflammatory dosage) effectively reduced the bumps and pus-filled lesions of rosacea.

Not having to take an antibiotic for the long term represents a major advancement in the treatment of the bumps, pus-filled pimples, and redness of rosacea. Long-term use of an antibiotic can cause undesirable side effects such as extreme sun sensitivity, yeast infections in women, and antibiotic resistance. The latter occurs when an antibiotic becomes ineffective because a person takes the antibiotic too often or for too long.

These research findings also provide more evidence that rosacea is a medical condition. It is clear that chemical processes in the body have gone awry, so rosacea is clearly not just a cosmetic concern.

More Research Needed
Before these findings can be used to develop treatment for rosacea, more questions must be answered. The researchers need to know why people with rosacea have these high levels of cathelicidin. They must explain why these high levels lead to inflammation. They also need to find out if other agents produced by the nerves can cause the effects similar to ATP.

The researchers have already begun the studies needed to answer these questions. What they discover next could change the face of rosacea treatment. It also could show, as have past studies, that there is an association but nothing more.

References:
Del Rosso JQ. “Recently Approved Systemic Therapies for Acne Vulgaris and Rosacea.” Cutis 2007; 80: 113-19.

Gillette B. “Rosacea: Advances, setbacks. Study sheds new light on cause; tests halted on one new therapy.” Derm Times, 2007; 28(11):1, 68.

Los Angeles Times. “Research unravels mystery of rosacea.” Reprinted in Chicago Tribune, August 6, 2007, section 1, page 3.

Melville NA. “Study: Two-step problem. Abnormal peptide expression, enzyme levels linked to acne rosacea.” Derm Times. 2007; 28(11):59.

Webster GF. “Rosacea and Related Disorders.” In: Bolognia JL, Jorizzo JL, Rapini RP et al, editors. Dermatology, Spain, Mosby Elesevier; 2008. p. 509.

Yamasaki K, Di Nardo A, Bardan A et al. “Increased serine protease activity and cathelicidin promotes skin inflammation in rosacea.” Nat Med 2007; 13: 975-80.

All content solely developed by the American Academy of Dermatology