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Graphic illustrating the areas of the face most often affected by rosacea, from Wikimedia Commons

Study finds allergy-like reaction may trigger rosacea

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Graphic listing symptoms of rosacea: Affects 14 million Americans; Is characterized by redness on the cheeks, nose, chin or forehead; small visible blood vessels; bumps or pimples; watery or irritated eyes; Can cause facial burning, stinging and itching; facial swelling; a 'WC Fields nose' (aka rhinophyma); dry, flaky skin;

File this under news that won’t come as a shock to many of us here in Masto-Land (slang reference to the community of people who have IA, mastocytosis, MCAD, or related diseases).

Photograph of Dr. Richard Gallo, taken from the UCSD Web site

Dr. Richard Gallo, who is the Chief of the Division of Dermatology at the University of California at San Diego, presented a study [National Rosacea Society. Study Finds Allergy-Like Reaction May Trigger Bumps and Pimples. Rosacea Review. Fall 2006] at the National Rosacea Society research workshop during the May 2006 annual meeting of the Society for Investigative Dermatology, which detailed his research into the inflammatory process that leads to rosacea [a condition that causes chronic dilation of blood vessels on the nose and cheeks].

Using a mass spectrometer [a device that uses a magnetic field to separate ions in order to determine the molecular structure of a substance] to analyze the makeup of proteins found in the facial skin of rosacea patients, researchers found an abnormality in the production of cathelicidins [a major family of antimicrobial peptides that are part of our bodies' innate immune system].

Don’t be surprised if you’ve never heard of cathelicidins before — they were discovered only recently, in 1993. Reference [Zanetti M. Cathelicidins, multifunctional peptides of the innate immunity. J. Leukoc. Biol. 2004;75:39–4]. What are they? They are small, antimicrobial peptides [a compound of two or more amino acids connected by a specific kind of bond] secreted by several different kinds of cells, including epithelial [skin or other outermost layers of cells covering mucous membrances, blood vessels, glands, etc.] cells, macrophages, and neutrophils [two kinds of white blood cells, which are part of our immune system].

Anyway, these cathelicidins are part of our innate immune system, and in people who don’t have rosacea, their cathelicidin is in an inactive state. However, people who have rosacea have forms of cathelicidins that promote skin inflammation.

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Activating cathelicidin

Graphic showing how cathelicidin becomes activated

How do cathelicidins become inflammatory? This seems to be due to the overabundance of another substance that plays a big role in both inflammation and rosacea: kallikrein [a group of enzymes involved in inflammatory processes]. It seems that the kallikrein activates previously dormant cathelicidins, which in turn can lead to the bumps and pimples found in moderate to severe rosacea.

When the researchers took cathelicidins from human rosacea patients and injected them into the skin of mice, the rodents showed a dramatic inflammatory response, whereas mice injected with cathelicidins from people without rosacea showed no inflammation at all — not even on a microscopic level.

Given that our super-abundant or defective mast cells predispose us to inflammation and that many of us have rosacea, I don’t think most of us will have trouble accepting Dr. Gallo’s findings. The exciting part is that his work may help lead to better and more effective treatments for rosacea.

A more recent article (Schauber J and Gallo RL. Antimicrobial peptides and the skin immune defense system. J Allergy Clin Immunol. 2008;122:261–6) summarizing the work of Gallo and others on cathelicidins is also available.

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An earlier version of this article appeared in the Winter 2007 issue of The Mastocytosis Chronicles, the quarterly newsletter of the Mastocytosis Society (TMS).

Page last updated: March 20, 2011

All information contained in this site is one layperson's interpretation of medical journal articles, textbooks, seminars, presentations, and other materials. Nothing that is stated here should carry more weight than the informed and considered opinions of your own highly trained and qualified medical caregivers. The author of this site is not a doctor and has absolutely no authority to prescribe or diagnose.

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