Intestinal bacteria protect against food allergy

Study: Bacteria can protect against food allergy

08/26/2014

More and more people in Germany suffer from food allergies. Since these can hardly be treated, sufferers do without the allergy-inducing foods. Researchers have now discovered that certain intestinal bacteria can protect against the disease.

Six million food allergy sufferers
The number of people with food allergies in Germany is increasing. According to experts, it has doubled in the last ten years. According to estimates by the German Allergy and Asthma Association (DAAB), around six million people are said to be affected by a food allergy. Among the frequent triggers include various crustaceans, fish, various legumes (peas), fruit (cherries), vegetables (celery), mustard seeds, cereals (buckwheat) or histamine (in cheese). Often there is already a pollen allergy, which leads to a cross allergy.

Certain bacteria can protect against food allergies
As it turns out, "certain intestinal bacteria seem to protect against food allergies." According to a dpa report, an international research team on mice showed that the microorganisms of the genus Clostridia inhibit the transfer of allergy-causing substances from the intestine into the blood. The researchers around Cathryn Nagler from the University of Chicago write in the „Proceedings“ the US National Academy of Sciences („PNAS“) that "possibly probiotic therapies could help against the otherwise barely treatable food allergies".

Various possible causes of increase in allergies
Not only in Germany, but generally in industrialized countries, the number of people with allergies has been increasing for a long time. The proportion of affected children in the United States increased from 1997 to 2007, according to the health authority CDC by 18 percent. Experts suspect a number of causes, including a changed intestinal flora. „Environmental influences such as excessive use of antibiotics, high-fat diet, caesarean birth, elimination of common pathogens and even breast milk substitutes affect the microorganisms with which we develop together“, said Nagler in a statement from her university. „Our results suggest that this contributes to increasing sensitivity to food allergies.“

Influence of intestinal flora on mice tested
The researchers tested in mice the influence of the intestinal flora. They confronted two groups of mice with allergy-causing substances, so-called allergens, from food. One of the animals lived under sterile conditions and the other was treated with antibiotics after birth, reducing the intestinal flora. These two groups produced antibodies to peanut allergens to a greater extent than mice with normal intestinal flora. However, when the scientists then administered common Clostridia bacteria to rodents in humans, the sensitivity dropped. A second large group of intestinal inhabitants, the Bacteroides, did not have this effect.

Less allergens get into the bloodstream
In a second step, the researchers examined the mechanisms behind the protective effect. Clostridia thus ensure that immune cells produce large amounts of interleukin-22 (IL-22). This signal substance reduces the permeability of the intestinal mucosa and also with IL-22, the researchers were able to reduce the peanut sensitivity of the mice. The results suggest that Clostridia microbes, by stimulating IL-22 production, are responsible for fewer allergens entering the bloodstream.

Intestinal flora a good target for therapeutic intervention
„We have identified a bacterial population that protects against sensitization to food allergens“, Nagler explained. „The first step towards sensitization is for an allergen to enter the blood and be presented to the immune system. The presence of these bacteria regulates this process.“ However, the researchers acknowledge that this is not the only factor. However, the scientists - who have already applied for a provisional patent - emphasized that the intestinal flora is a good target for therapeutic interventions, and that it is easy to verify. „It's exciting because we know the bacteria“, so Nagler. „We now have a chance to intervene.“

Those affected abstain from allergy-causing foods
Whether the new findings lead to concrete therapies is unclear. Food allergy sufferers will probably continue to do without the respective allergy-inducing foods, as the disease can hardly be treated. Symptoms that can frequently occur in a food allergy include, for example, diarrhea, abdominal pain, nausea, and vomiting. Many people with allergies also have to deal with complaints such as swollen lips, shortness of breath, skin redness or an itchy rash. In particularly severe cases, the reaction can lead to an allergic shock with a drop in blood pressure and a rise in heart rate to cardiac arrest. (Ad)

Picture: Sigrid Rossmann