Whether certain proteins made by the immune system may trigger the onset of rosacea is the subject of a study sponsored by a National Rosacea Society research grant and conducted by Dr. Richard Gallo, associate professor of dermatology and pediatrics at the University of California - San Diego and Dr. Masamoto Murakami, postdoctoral scientist, Veterans Medical Research Center. While acting to protect the body, the proteins also may trigger some of rosacea's symptoms, the researchers hypothesize.

"If this theory proves true -- that rosacea is in some way a disorder of the innate immune system -- then completely new therapeutic approaches can be developed to treat this disease," Dr. Gallo said.

The immune system, which is responsible for the body's ability to combat illness and infection, produces its own antibacterial agents that fight disease and heal wounds, Dr. Gallo said. These natural substances act by eliminating the presence of harmful bacteria and activating other parts of a complex immune reaction. Either irritation or infection may stimulate the production of these proteins, he noted.

Dr. Gallo's laboratory is investigating whether the immune system response, including the expression of a natural protein called a cathelicidin, may cause some of the signs and symptoms of rosacea.

In their initial research, Dr. Gallo and his colleagues found an abnormally high level of cathelicidins upon histopathological staining in the skin of patients with rosacea. They further noted that some hallmarks of rosacea, including inflammation and growth of blood vessels, are associated with cathelicidins.

In a second study, the researchers are now investigating whether the redness, inflammation and blood vessel growth of rosacea are a result of an abnormal expression of this natural antibiotic. Using immunohistochemistry and quantitative polymerase chain reactions, Dr. Gallo and his colleagues found that in rosacea the chronic production of cathelicidins appears to be ineffective in inhibiting the spread of bacteria, and may instead simply trigger rosacea's signs and symptoms.

The researchers plan to further test their hypothesis by examining the effect of cathelicidins in mice and on human blood cells.