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Peril on the Plate

Odkrywaj Life Science

  • Off the Bench
  • Odkrywanie życia
  • Doświadczenie

Allergy sufferers are longing for foods that they can enjoy without second thought. New molecular processes may be able to ease their lives. Even so, hypoallergenic products are still a long way away.

Death lurks on the supermarket shelf. Cow’s milk, nuts, soy, wheat, fish or eggs: if such ingredients hide in, for example, ready-made meals, and an unsuspecting allergy sufferer is not careful, the worst outcome may be death. “Food allergies are not a trend or a lifestyle choice”, emphasizes the managing director of the American organization FARE® (Food Allergy Research & Education®), Lisa Gable. “Families and adults living with this disease must be vigilant at all times, because in a matter of minutes, an allergic reaction can send someone to the emergency room with anaphylaxis.

The prevalence of food allergies and anaphylactic reactions is on the rise in Western industrialized nations. One of the causes, researchers suspect, includes the increased utilization of peanuts. Peanuts are found in granola bars, chocolate, sauces and ready-made meals – even in shampoos and body lotions. According to estimates, 5.4 million people suffer from a dangerous peanut allergy in the US and Europe alone.


Soy for starters


Thus far, allergy sufferers have only one option: they must avoid foods that contain their trigger. This is the reason that scientists are now working on the development of hypoallergenic foods. To this end, they are developing methods which will first identify those components which trigger the allergy, and subsequently neutralize them. “Until now, with the sole exception of baby food, no hypoallergenic foods are available on the market. Their production is highly complex”, says Dr. Michael Szardenings of the Fraunhofer Institute for Cell Therapy and Immunology (IZI) in Leipzig, Germany. This has been partly due to the fact that the specific allergenicity of foods could not be established.

This is exactly what Szardenings and colleagues have now achieved for soy. They developed a process that allows the direct detection and determination of those protein components (epitopes) which are recognized by the soy-allergy sufferer’s antibodies, and which thus trigger the allergy, directly from the antibodies present in the serum. By applying this method, the researchers detected 374 allergy-relevant epitopes in soy. Using different heating methods, as well as treatment with plasma, pulsed UV-light, gamma-radiation and high pressure, chemical, enzymatic and fermenting processes, the researchers at the Fraunhofer Institute for Process Technology and Packaging (IVV) subsequently altered soy proteins in such a way that they have become less allergenic.


Genome editing with CRISPR/Cas9


Genome editing processes, too, have yielded promising results. This method allows the switching off of certain genes in plants so that ribosomes inside the cells will no longer produce the allergy-triggering proteins. The new CRISPR/Cas9 process is precise and easy to use. Using so-called “gene scissors”, researchers can alter the genomes of plants by cutting, switching off or inserting new gene sequences.

Scientists at the Biotech start up Aranex at the University of Warwick, among others, are employing the gene scissors to knock out three peanut allergens. It is, however, considered unlikely that this will be sufficient to protect allergy sufferers. The peanut, after all, contains many additional allergy triggering proteins. If all genes responsible were to be excised, the plant, most likely, would not be able to survive.

In addition, a reduction of the gluten-content of wheat by means of the gene scissors has recently been successfully achieved by researchers in Spain. Antibody assays showed that immune reactivity following the consumption of the modified bread and durum wheat was reduced by up to 85 percent as compared to the control group. Similar successes have previously been attained by researchers in the US and Spain using RNA interference (RNAi), a method which blocks genes in a targeted fashion.

People who suffer from a milder cross-sensitivity may find relief by simply choosing a different variety. As such, researchers at the Technical University in Munich, Germany, discovered that with tomatoes and strawberries, for example, the allergen content varies considerably across individual varieties – a phenomenon that has been known to occur also in apples. The results will serve as a basis for the selected breeding of hypoallergenic varieties.

Despite scientific progress, it still remains doubtful whether foods for extremely vulnerable allergy sufferers will ever reach supermarket shelves. “Marketing of hypoallergenic foods produced from genetically modified crops is currently not feasible as these varieties would have to be accurately differentiated from unmodified, fully allergenic varieties”, states a German-American team of researchers in the journal Molecular Allergy Diagnostics. This renders the production process risky and expensive – and therefore less attractive to companies.

Infobox

During the course of a true food allergy, the immune system reacts to the proteins in a specific food. Often, minute amounts of that food are sufficient to trigger symptoms. Cross-sensitivities against pollen-associated foods, however, are an entirely different entity. For example, a person who is allergic to airborne birch or hazelnut pollen will often not tolerate certain fruits such as apples, cherries or kiwis. In these cases, the immune system confuses the apple with birch pollen. All other reactions to food constitute food intolerances, i.e. non-allergenic hypersensitivities. While these hypersensitivities are caused by mechanisms distinct from the immune system, their symptoms frequently resemble those of “true” allergies.