Scientists find new piece in peanut allergy puzzle

Related tags Allergy Asthma

Fundamental science identifies a further piece in the puzzle of why
humans are allergic to peanuts, tracking proteins from the gut to
the immune system, writes Lindsey Partos.

Peanut allergies are rising in humans, with an estimated 2.5 million people in Europe and the US now vulnerable to the food allergy. UK scientists led by Dr Claudio Nicoletti at the Institute of Food Research claim to have discovered the route and type of transport taken by peanut proteins through the gut to the immune system.

"The main implication of the study is that peanut proteins are delivered to the gut immune system via a specific form of cell,"​ Dr Nicoletti explained to FoodNavigator.com.

This is a highly immunogenic route that might be extremely important in the allergen response to peanuts, he added.

While it is too early to tell the implications that the IFR study will have on the food industry, escalating incidences of food allergies in Europe and the desire to avoid potentially harmful consumer confusion underpinned changes to the Labelling Directive 2000/13/EC due to enter into force this month that essentially flag up to the consumer possible allergens in a food product.

The amendment heralds the mandatory inclusion on food labels of the most common food allergen ingredients and their derivatives: cereals containing gluten, fish, crustaceans, egg, peanut, soy, milk and dairy products including lactose, nuts, celery, mustard, sesame seed, and sulphites.

There is no current cure for food allergy and vigilance by an allergic individual is the only way to prevent a reaction but a peanut allergy can be so severe that only very tiny amounts can be enough to trigger a response.

Using a digestion model, Dr Nicoletti and his team found that digestion through the stomach and small intestine produces large amounts of soluble protein and intact protein bodies - large particle-like structures. Secondly, by labelling them with gold, Dr Nicoletti found that peanut proteins are delivered at high speed through the gut via M-cells.

M-cells are effective at rapidly delivering foreign bodies, including proteins, to defence cells. Protein bodies hitching a ride with M-cells are therefore likely to trigger defence cells into action.

In allergic reactions the body overproduces the antibody IgE causing many symptoms including skin rashes, wheezing, sneezing, swelling around the lips, bloating, vomiting and diarrhoea. In extreme cases it causes anaphylaxis, a life-threatening reaction triggered within minutes.

The neighbouring cells to M-cells are enterocytes. Proteins delivered via these cells are processed to form peptides, and when presented to the immune system are likely to induce tolerance.

"This research shows that antigens have the ability to dictate the route of transport, and in doing so the type of immune response that follows,"​ added Dr Nicoletti.

The next step according to the lead researcher is to understand why the peanut protein goes through the route to the M-cells. "What favours it? When we know that we can eventually try devices that could effectively help consumers avoid the allergy."

The IFR worked with the University of Sienna and the complete research will be published in the December issue of Biochemical and Biophysical Research Communications.

Related topics Science Food Safety & Quality

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