Skin and food allergies can be result of skin cell 'glue' defeciency

Scientists say that they've found that a structural defect in skin cells that may contribute to allergy development, including skin and food allergies, traditionally thought to be related to a dysfunction of the immune system.

The finding is related to the team's identification of a new rare genetic disease, called "severe dermatitis, multiple allergies, and metabolic wasting," or SAM, caused by mutations in the molecule desmoglein 1.

"Desmoglein 1 is best understood as the 'glue' that holds the outer layer of human skin together," said Kathleen Green, Joseph L. Mayberry, Sr., Professor of Pathology and Toxicology at Northwestern University Feinberg School of Medicine.

"Historically, the molecule was mainly believed to have a structural role: this adhesion between cells contributes to the physical barrier that regulates water loss and also acts as the body's major defense against environmental elements. But there are a large number of molecules that form this barrier, distributed in a highly-patterned manner, prompting our team to hypothesize that they do more than just mediate adhesion."

Green's group at Northwestern worked with an international team that analyzed clinical data from two families, combined with genetic analysis including next-generation DNA sequencing and light and electron microscopy, among other techniques. They found that when desmoglein 1 does not properly function or does not exist, the resulting barrier disruption can affect the immune response, and consequences can be severe.

"This work is also significant because it suggests that in addition to impairing the physical barrier, loss of desmoglein 1 may more directly regulate expression of genes that control the immune response and contribute to allergy," says Green. "Conceptually, it allows us to build on previous studies and make conclusions about the importance of other structural proteins in the skin barrier."

Green notes that the finding, combined with recent published data, could eventually lead investigators to discover further connections between defects in structural molecules and less severe allergies such as atopic dermatitis, eczema and more common food allergies.
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Food Allergies? Pesticides in Tap Water Might be to Blame

Food allergies are on the rise, affecting 15 million Americans. And according to a new study published in the December issue of Annals of Allergy, Asthma and Immunology, the scientific journal of the American College of Allergy, Asthma and Immunology (ACAAI), pesticides and tap water could be partially to blame.

The study reported that high levels of dichlorophenols, a chemical used in pesticides and to chlorinate water, when found in the human body, are associated with food allergies.

“Our research shows that high levels of dichlorophenol-containing pesticides can possibly weaken food tolerance in some people, causing food allergy,” said allergist Elina Jerschow, M.D., M.Sc., ACAAI fellow and lead study author. “This chemical is commonly found in pesticides used by farmers and consumer insect and weed control products, as well as tap water.”

Among 10,348 participants in a US National Health and Nutrition Examination Survey 2005-2006, 2,548 had dichlorophenols measured in their urine and 2,211 were included into the study. Food allergy was found in 411 of these participants, while 1,016 had an environmental allergy.

“Previous studies have shown that both food allergies and environmental pollution are increasing in the United States,” said Dr. Jerschow. “The results of our study suggest these two trends might be linked, and that increased use of pesticides and other chemicals is associated with a higher prevalence of food allergies.”

While opting for bottled water instead of tap water might seem to be a way to reduce the risk for developing an allergy, according to the study such a change may not be successful.

“Other dichlorophenol sources, such as pesticide-treated fruits and vegetables, may play a greater role in causing food allergy,” said Dr. Jerschow.

According to the Centers for Disease Control and Prevention, an increase in food allergy of 18 percent was seen between 1997 and 2007. The most common food allergens are milk, eggs, peanuts, wheat, tree nuts, soy, fish, and shellfish.

Food allergy symptoms can range from a mild rash to a life-threatening reaction known as anaphylaxis. The ACAAI advises everyone with a known food allergy to always carry two doses of allergist prescribed epinephrine. A delay in using epinephrine is common in severe food allergic reaction deaths.

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