Peanut allergy, like other food allergies, currently has no
cure. Scientists are conducting clinical trials of doctor-supervised
immunotherapy, in which peanut-allergic patients take increasing amounts of
peanut powder to try to desensitize them to the peanut allergen. At the end of
the trial, patients are usually asked to eat some peanuts every day for the
rest of their lives.
The gradual introduction of small doses of peanuts to people
with a peanut allergy could alter how their DNA reacts, according to new
research from Stanford University and Packard Children’s Hospital. The research
supports a growing body of evidence for oral immunotherapy (OIT) including
recent positive results from the University of Cambridge. This latest study,
published in the journal The Lancet, suggests that when kids slowly increase
their tolerance to the allergen, OIT changes how their genes express themselves
inside the body.
"At first, eating two peanut butter cups a day might
seem fun, but it gets a little boring and a lot of people might stop,"
said Kari Nadeau, MD, PhD, associate professor of pediatrics at Stanford and an
immunologist at Stanford Hospital & Clinics and Lucile Packard Children's
Hospital Stanford. Until now, doctors could not test whether patients who had
completed immunotherapy could safely stop eating daily doses of peanuts, she
said. "Our new finding can help us try to determine whether, for the long
term, someone's allergy has truly been shut off so people can eat ad lib."
Nadeau is the senior author of a paper describing the new
findings, which will be published online Jan. 31 in the Journal of Allergy and
Clinical Immunology.
Currently, doctors have no cure for peanut allergies, which
can cause severe reactions including death. In the study, researchers examined
the blood cells of a group of 20 peanut-allergic children and adults who had
undergone immunotherapy for two years. That meant that doctors had these
patients eat gradually increasing amounts of peanut powder every day for two
years until they became desensitized to the allergen. At the start of the
trial, the patients were already able to eat four grams of peanuts every day
with no signs of an allergic reaction.
To test the success of the immunotherapy (and find out the
mechanisms behind it) the doctors told the patients to stop eating peanuts for
three months, and then gave them a small dose. Seven out of the 20 patients had
no reaction to the peanuts, while 13 regained their allergy. The researchers
compared the white blood cells of the patients who could now tolerate peanuts
with a control group who had never had immunotherapy before. More specifically,
the researchers looked at the genes within these white blood cells.
For the patients who never received immunotherapy (the
control group), a large number of chemical tags called methyl groups were now
affixed to their DNA. These methyl groups controlled how certain genes actively
expressed themselves in the body. The large clump found on the control group’s
genes had locked, or silenced, the genes that were supposed to help them fight
off the allergic reactions.
In contrast, the researchers found that the seven patients
who could now tolerate peanuts showed a very sparse number of methyl groups on
their DNA, meaning that the genes that help them control their allergic
reactions were free to actively work within their body.
The research was funded by Food Allergy Research &
Education, the Fund for Food Allergy Research at Stanford, the National
Institute of Allergy and Infectious Diseases (grant R211R21AI09583801) and the
Children’s Health Research Institute/Lucile Packard Foundation for Children’s
Health. The research also was supported by the National Center for Research
Resources (grant UL1RR024128) and the National Center for Advancing
Translational Science (grant UL1TR000093).
Source :
http://esciencenews.com/articles/2014/02/03/dna.peanut.allergic.kids.changes.with.immune.therapy.stanfordpackard.study.finds
http://med.stanford.edu/ism/2014/january/peanut.html
http://www.medicaldaily.com/peanut-allergy-oral-immunotherapy-changes-dna-alteration-gene-expression-possible-way-monitor-268328
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