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¡°We¡¯ve identified a bacterial population that protects against food allergen
sensitization,¡± Nagler said. ¡°The first step in getting sensitized to a food
allergen is for it to get into your blood and be presented to your immune
system. The presence of these bacteria regulates that process.¡± She cau-
tions, however, that these findings likely apply at a population level, and
that the cause-and-effect relationship in individuals requires further study.
While complex and largely undetermined factors such as genetics greatly
affect whether individuals develop food allergies and how they manifest,
the identification of a bacteria-induced barrier-protective response rep-
resents a new paradigm for preventing sensitization to food. Clostridia
bacteria are common in humans and represent a clear target for potential
therapeutics that prevent or treat food allergies. Nagler and her team are
working to develop and test compositions that could be used for probiotic
therapy and have filed a provisional patent.
¡°It¡¯s exciting because we know what the bacteria are; we have a way to in-
tervene,¡± Nagler said. ¡°There are of course no guarantees, but this is abso-
lutely testable as a therapeutic against a disease for which there¡¯s nothing.
As a mom, I can imagine how frightening it must be to worry every time
your child takes a bite of food.¡±
¡°Food allergies affect 15 million Americans, including one in 13 children,
who live with this potentially life-threatening disease that currently has
no cure,¡± said Mary Jane Marchisotto, senior vice president of research at
Food Allergy Research & Education. ¡°We have been pleased to support the
research that has been conducted by Dr. Nagler and her colleagues at the
University of Chicago.¡± (source: University of Chicago Medical Center. ¡°Gut
bacteria that protect against food allergies identified.¡± ScienceDaily, 25 Au-
gust 2014.
Bacteria That Protects Against Food Allergies Identified
Represents a new paradigm for preventing sensitization to food
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New study: Clostridia, a common class of gut
bacteria, protects against food allergies
August 25, 2014, University of Chicago Medical
Center: The presence of Clostridia, a common class
of gut bacteria, protects against food allergies, a
new study in mice finds. By inducing immune re-
sponses that prevent food allergens from entering
the bloodstream, Clostridia minimize allergen ex-
posure and prevent sensitization - a key step in the
development of food allergies. The discovery points
toward probiotic therapies for this so-far untreatable
condition, report scientists from the University of
Chicago, Aug 25 in the Proceedings of the National
Academy of Sciences.
Although the causes of food allergy - a sometimes
deadly immune response to certain foods - are
2014 SEPTEMBER #5-8
unknown, studies have hinted that modern hygienic or dietary practices
may play a role by disturbing the body¡¯s natural bacterial composition. In
recent years, food allergy rates among children have risen sharply, increas-
ing approximately 50 percent between 1997 and 2011, and studies have
shown a correlation to antibiotic and antimicrobial use.
¡°Environmental stimuli such as antibiotic overuse, high fat diets, caesar-
ean birth, removal of common pathogens and even formula feeding have
affected the microbiota with which we¡¯ve co-evolved,¡± said study senior
author Cathryn Nagler, PhD, Bunning Food Allergy Professor at the Univer-
sity of Chicago. ¡°Our results suggest this could contribute to the increasing
susceptibility to food allergies.¡±
To test how gut bacteria affect food allergies, Nagler and her team investi-
gated the response to food allergens in mice. They exposed germ-free mice
(born and raised in sterile conditions to have no resident microorganisms)
and mice treated with antibiotics as newborns (which significantly reduces
gut bacteria) to peanut allergens. Both groups of mice displayed a strong
immunological response, producing significantly higher levels of antibodies
against peanut allergens than mice with normal gut bacteria.
This sensitization to food allergens could be reversed, however, by rein-
troducing a mix of Clostridia bacteria back into the mice. Reintroduction
of another major group of intestinal bacteria, Bacteroides, failed to allevi-
ate sensitization, indicating that Clostridia have a unique, protective role
against food allergens.
Closing the door
To identify this protective mechanism, Nagler and her team studied cellular
and molecular immune responses to bacteria in the gut. Genetic analysis
revealed that Clostridia caused innate immune cells to produce high levels
of interleukin-22 (IL-22), a signaling molecule known
to decrease the permeability of the intestinal lining.
Antibiotic-treated mice were either given IL-22 or
were colonized with Clostridia. When exposed to pea-
nut allergens, mice in both conditions showed reduced
allergen levels in their blood, compared to controls.
Allergen levels significantly increased, however, after
the mice were given antibodies that neutralized IL-22,
indicating that Clostridia-induced IL-22 prevents al-
lergens from entering the bloodstream.
Artist¡¯s rendering of bacteria (stock
illustration). Credit: zuki70 / Fotolia
¡°This is absolutely testable as a
therapeutic against a disease for
which there¡¯s nothing.¡± - Cathryn Nagler,
PhD, Bunning Food Allergy Professor, University of Chicago