Weblog

Possible Role for Mites

Tuesday, October 30, 2007

Although they are normal inhabitants of human skin and cannot be seen, microscopic mites known as Demodex folliculorum may actually be something to blush about, as a new study funded by the National Rosacea Society demonstrated for the first time that these invisible organisms may be a cause or exacerbating factor in rosacea.

"While it is well established that Demodex occur in far greater numbers on the faces of people with rosacea, it was uncertain whether they play a role in the development of the disorder," said Dr. Frank Powell, consultant dermatologist at Mater Misericordiae Hospital in Dublin, Ireland, who conducted the study along with colleagues at the National University of Ireland-Maynooth. "In other words, which came first, the mites or the rosacea? And now there is evidence that it might be the mites."

In the new study, published in the British Journal of Dermatology, the researchers identified Bacillus oleronius as distinct bacteria associated with Demodex mites. When analyzing blood samples using a peripheral blood mononuclear cell proliferation assay, they discovered that B. oleronius stimulated an immune system response in 79 percent of 22 patients with subtype 2 (papulopustular) rosacea, compared with only 29 percent of 17 subjects without the disorder.

"The immune response results in inflammation, as evident in the papules (bumps) and pustules (pimples) of subtype 2 rosacea," Dr. Powell said. "This suggests that these bacteria found in the mites could be responsible for the inflammation associated with the condition."

Dr. Powell noted that the potential role for the bacteria in subtype 2 rosacea is also supported by the fact that effective treatment includes antibiotics that destroy B. oleronius. Interestingly, he said, antibiotics that are not harmful to these bacteria generally are not effective in the management of rosacea.

"Although the mechanism of antibiotics in treating rosacea is not definitively understood, it has long been suggested that they work through anti-inflammatory action," he said. "However, other anti-inflammatory drugs are ineffective in treating rosacea, and immunosuppressive agents such as steroids can ultimately make the inflammation worse."

The researchers concluded that their study shows consideration must also be given to the potential for antibiotics to affect microorganisms such as B. oleronius or other follicular or mite-related bacteria.

Reference: Lacey N, Delaney S, Kavanagh K, Powell FC. Mite-related bacterial antigens stimulate inflammatory cells in rosacea. Br J Dermatol 2007;157:474-481.

Scoring Aids Eye Research

Tuesday, October 9, 2007

Special care may be needed for rosacea patients with severe forms of ocular rosacea (eye symptoms), according to Dr. Sandra Cremers, instructor of ophthalmology at Harvard Medical School. As part of a National Rosacea Society (NRS) research grant, she recently developed a scoring system to identify severe cases of this rosacea subtype, which may affect half of all rosacea patients.

The new questionnaire, called the Severity Criteria of Ocular Rosacea (SCOR), includes more than 25 signs and symptoms of ocular rosacea observed by both physician and patient, including eye dryness, tearing and burning; history of styes; inflammation; and potentially vision-threatening corneal involvement. The system was presented in a poster at the recent annual meeting of the American Academy of Ophthalmology.

Although ocular rosacea is often very mild, in an NRS survey of 1,780 rosacea patients reporting ocular symptoms, only 27 percent said they had been diagnosed with the condition, possibly indicating underdiagnosis.

Left untreated, patients with severe ocular rosacea could endure potentially serious consequences, such as scarring within the eyelid or corneal damage that could lead to decreased vision.

Dr. Cremers noted that for mild symptoms such as dry eye, a humidifier or other means to raise the humidity at home or in work environments as well as artificial tears may be appropriate.

In addition, washing the eyelashes daily with diluted baby shampoo on a warm wet washcloth may help keep the tear glands clear and unblocked. A hot compress can be placed on the eye for five minutes before the diluted baby shampoo is used to gently clean the eyelid margins. Then the face may be rinsed with closed eyes until the eyelashes feel clean and towel-dried. An eye doctor may also prescribe a cream for the lashes, Dr. Cremers said.

The researchers are now using the SCOR questionnaire to identify patients with severe ocular rosacea to evaluate the role of angiogenesis, which is the formation of new blood vessels in the disorder. Dr. Cremers noted that while new blood vessel growth is important for normal development and wound healing, this process is also implicated in some diseases.

Also, rosacea triggers such as sunlight have been linked to an increase in substances that may cause angiogenesis or inflammation, such as vascular endothelial growth factor (VEGF). Dr. Cremers and her group are currently investigating whether samples from severe cases of ocular rosacea contain any of these natural substances.