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Researchers discover way to turn off severe allergic reaction to food in mice

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October 3, 2010

A bowl of nuts - delicious for some, potentially deadly for others (Image: Craig Engbrecht...

A bowl of nuts - delicious for some, potentially deadly for others (Image: Craig Engbrecht)

There is no known cure for food allergies with sufferers forced to constantly check the ingredients on food packaging and make enquiries at restaurants before digging into a meal. Even taking such precautions it is almost impossible to avoid all food allergen exposure, especially with children. With even minor exposure having the potential to cause severe or even life threatening reactions in some people, the discovery of a way to turn off the immune system’s allergic reaction to certain proteins in mice, could have implications for the millions of food allergy sufferers worldwide.

Allergic reactions to food occur when the immune system misidentifies an otherwise innocuous food protein as harmful, and then attacks the protein with a ferocity far greater than required. Last year we reported that a team at Duke University discovered it was possible for some people allergic to peanuts to build up a tolerance by slowly giving them higher and higher doses of peanut flour in their food each day. While promising, for this method to remain effective the subjects had to keep a daily dose of peanuts in their diets to maintain the tolerance.

Now a research team at Johns Hopkins University has discovered that one kind of immune cell in the gastrointestinal tract called lamina propria dendritic cells (LPDC), which are considered the first line of defense for a body’s immune system, expresses a special receptor, SIGNR1, which appears on the cells’ surface and binds to specific sugars.

Test results on mice

In the laboratory, the research team, led by Shau-Ku Huang, Ph.D., a professor of medicine, and Yufeng Zhou, M.D., Ph.D., a postdoctoral fellow in the Division of Allergy and Clinical Immunology at Johns Hopkins University School of Medicine, took a food protein that causes allergies in mice and modified it by adding special sugars.

They hypothesized that, when ingested by the mice, the modified proteins would be able to bind to what are known as the SIGNR1 receptors on the immune system cells. Bound in this way, the immune system would learn to tolerate the modified food protein – and the protein would no longer induce an allergic reaction, even when consumed in its unmodified form.

The mice were fed the modified protein once a day for three days. Five days later, they were fed the protein in its unmodified form. Another group of mice was not fed the modified protein at all. The severity of the allergic response to the unmodified protein – which in the control-group mice tended to be tremors, convulsions and/or death – was significantly decreased in those mice that had been pre-fed the modified protein.

Some still had minor reactions like itchiness or puffiness around the eyes and snout, but none had serious ones. These mice appeared to be desensitized to the food protein, even when it was fed to them in its unmodified form, says Zhou. In this model, SIGNR1 plays a key role in shutting off some responses in the immune cells, but the researchers don’t yet know whether this is the only function of this receptor.

Growing problem

In the U.S., it is estimated that six to eight percent of children under the age of three and nearly four percent of adults have food allergies. And the prevalence of allergies is rising, particularly in the developed world, with children growing up in too sterile an environment thought to be a major contributing factor.

Whatever the reason, if the Johns Hopkins team can confirm that their process in mice can also occur in humans it will provide hope that the body could be trained to tolerate food allergies that lead to roughly 300,000 emergency room visits and 100 to 200 deaths each year in the U.S. alone – and it could also mean that one day I might be able to try a peanut butter sandwich and see what all the fuss is about.

The research team's findings are published online in the journal Nature Medicine.

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag.   All articles by Darren Quick
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3 Comments

Actually, there is a known cure for it. It is well documented on the web last year. Patients were given minute amounts of the antagonistic food-stuff, in that case peanuts, and gradually they built up a tolerance. It was particular to peanuts.

http://news.bbc.co.uk/1/hi/8527530.stm

Jamie_S
4th October, 2010 @ 03:20 am PDT

I guess another way of looking at the prevalence of allergies in the "developed" world is to correlate it with the amount of immune-system tinkering.

We don't know how the immune system works exactly, yet we think we can improve on it. We give 3 year olds dozens of injections targetting their immune system, then wonder what on earth the cause might be when their immune system plays up.

Duh.

I'm just waiting for the penny to drop, and someone to correlate incidence of allergy to incidence of immunisation. But that sort of research could never be allowed to see the light of day.

Adrien
4th October, 2010 @ 11:52 am PDT

Of course we don't know everything about the immune system, we know everything about practically nothing.

Bit clearly we know enough about it to create immunizations against terrible ailments like polio, small pox and influenza's, all killers on a grand scale before immunization.

The idea that immunization is the cause of allergies has been tested and tested, always with the same results. It is wing nuts that stop immunizing their kids that put us at risk, as evidenced by breakouts of measles recently after decades of no cases.

There may be some side effects of vaccines, we aren't perfect but the danger from anti-science fanatics is much, much greater.

Joe Stafura
5th October, 2010 @ 08:08 am PDT
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