Nearly 8% of children under the age of three and 4% of adults suffer
from food allergies, which cause not only unpleasant symptoms such as
dermatitis and diarrhea, but can cause fatal anaphylactic shock. Allergic
reactions occur when food ingredients, such as eggs, shellfish, or peanut
proteins, stimulate white blood cells called mast cells, and excessive amounts
of histamine or cytokines enter the bloodstream, resulting in inflammation of
the skin, eyes, or gastrointestinal tract.
In 2012, researchers reported that a small protein called histamine-releasing
factor (HRF) plays a pro- inflammatory role in asthma. The work continued this
year, and it turned out that this protein also serves as an
“amplifier” of food allergies. A new biochemical mechanism is reported
to regulate this factor, paving the way for the development of blood tests that
can help predict which patients will respond to allergy therapy , supporting
the idea that drugs designed to block said protein could prevent food allergies
.
Allergens increase levels of antibodies called immunoglobulin E (or IgE ),
which then bind to mast cells, and when the allergen hits IgE , histamine is
released, according to the authors of the study. Early in the study, scientists
suspected that allergens were often present at very low levels, perhaps too low
to activate mast cells in this way. Recent evidence has confirmed that after
triggering allergens, histamine-releasing factor binds to IgE and then
activates mast cells, increasing inflammation.
To test the theory, the team raised mice sensitive to egg white and treated
them with an oral histamine-releasing protein inhibitor developed by the lab
for use in asthma-related experiments. To test the effectiveness of the
inhibitor, the scientists re-exposed treated and untreated mice to the
allergen. As expected, the untreated mice developed diarrhea and signs of
intestinal inflammation. However, these symptoms were delayed or significantly
less pronounced in mice treated with an inhibitor that reduced the reactivity
of mast cell allergens isolated from the intestines of allergic mice. to treat
people with food allergies, the authors say. The team observed higher levels of
IgE antibodies highly sensitive to HRF in the blood of egg-allergic children,
indicating that HRF contributes to food allergies in humans, as it does in
mice.
The group then followed the same children after starting an anti-allergic
treatment called oral allergy immunotherapy, in which patients consume
increasing amounts of eggs several times a day for several weeks. Once patients
achieve desensitization, they continue to consume eggs for twelve months. Egg
products are then withdrawn from the diet for two weeks before repeated
exposure to egg protein, as a test of the strength of the therapy. two weeks
after cessation of therapy, a low level of IgF- reactive IgE in the blood after
therapy was maintained. In contrast, children who showed re-sensitization to
egg whites immediately after interruption of therapy showed an increase in IgF-
reactive IgE .
The experiment showed that HRF is a potential target for drugs that are
effective in animal models. If a patient’s allergy goes unchecked regardless of
HRF levels, this could mean that the condition would be more difficult to
treat, the authors say. These tests also warrant future clinical monitoring of
HRF-resistant
IgE levels as a predictor of oral allergy immunotherapy outcomes. The lab
remains focused on developing potent HRF inhibitors and is currently testing
them using the mouse models described in the study. The goal of scientists is
to reduce the risk of developing allergic shock in patients. In the future,
such people may take an oral inhibitor as a preventive measure.