Cracked skin could be path to asthma

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eczemaResearchers have long noted that many asthma sufferers also have atopic dermatitis -- often called eczema -- a chronic disease of the skin that can leave it red, raw, scaly, tender, oozy and excruciatingly itchy. But scientists are looking at whether such ravaging of the skin creates the conditions that can trigger asthma.

British scientists reported last spring in the journal Nature Genetics that people who suffer from both eczema and asthma carry the same gene mutation and concluded that in some cases eczema may actually lead to asthma.

Until now, it had largely been assumed that dander, dust mites, pollen and other allergens that can cause asthma enter the body through the respiratory system. But the researchers said they now believe that they also can enter the body through tiny breaks in the skin's surface -- something that occurs in patients with eczema.

"Allergens from our environment can actually enter the skin through these cracks and the immune cells under the skin cells appear to be reacting and forming an allergic reaction" to them, said Dr. Thomas J. Hudson, an immunologist and the president and scientific director of the Ontario Institute for Cancer Research. He was not affiliated with the study but wrote a commentary on it in Nature Genetics.

That allergic reaction "can prime the immune system so that subsequent inhalation of the same allergens leads to a reaction in the lungs and contributes to the development of asthma," Dr. Julie Schaffer, an assistant professor of dermatology at New York University School of Medicine, wrote in an e-mail message.

The researchers also found that two gene mutations, known to diminish the skin's ability to form its protective outer barrier, were present in people with both asthma and eczema, confirming that the two can be genetically linked. But individuals who had asthma but no eczema did not have the mutations.

The lack of a direct link between asthma and the mutations -- when eczema was not present -- suggests that sensitization may arise after eczema sets in, as a result of a weakened skin barrier, Hudson concluded.

Doctors said their strongest hope is that the discovery could lead to new ways to prevent asthma in people who are genetically susceptible. The measures could be as simple as using moisturizer and gentle cleansers on babies and children to improve the health of their skin, said Dr. Jon M. Hanifin, a professor of dermatology at Oregon Health and Science University and a consultant to drug companies.

©2007 Star Tribune