Scientists developing wheat for celiac sufferers

Gene suppression | Researchers can silence 90 percent of the protein that causes an allergic reaction, but is that enough?

Since people with celiac disease react to specific proteins in wheat, the simple solution is to eliminate those proteins to develop an allergy-free wheat.

A team of scientists from Washington State University are attempting to do just that. Using a genetic technique called RNA interference, they have been able to silence the expression of more than 80 percent of the wheat genes associated with autoimmune reactions.

“With our molecular genetic technologies we have wheat plants that silence 85.6 percent of the immunogenic genes,” said Diter von Wettstein, a plant science professor at Washington State. “The chances of getting plants with more than 90 percent silencing is good.”

Von Wettstein and his Washington State colleagues, along with researchers in China and Germany, published a 2012 paper in the Proceedings of the National Academy of Sciences. In that paper, the scientists explained how they used RNA interference, or gene silencing, to prevent the formation of wheat proteins that affect celiac sufferers.

According to the U.S. National Institutes of Health, wheat is made up of three groups of proteins : gliadins, low molecular weight glutenin subunits and high molecular weight glutenin subunits.

The majority of people with celiac disease can tolerate the high molecular weight glutenin proteins, so the Washington State scientists attempted to silence the genetic expression of the other proteins in wheat.

“These proteins are not required for baking,” von Wettstein said in an email. “Such wheats aim, therefore, to provide flour that can be used for bread that will be compatible for the great majority of celiac patients.”

The high molecular weight glutenins are needed for baking, so the wheat should produce flour suitable for a variety of breads and dough.

While the gene suppressing technology is promising, Bob Zemetra, a wheat breeder an Oregon State University, wonders if it will be suitable for celiac sufferers.

“The issue that I would have and that’s the challenge of that (research) is you would need to have, in my mind, complete suppression,” said Zemetra, who collaborated with von Wettstein and others on the research.

“Depending on an individual sensitivity… how much is enough to trigger the reaction?”

Zemetra compared celiac disease to someone with a peanut allergy. In some cases even a minute quantity of peanut can trigger an anaphylactic shock. Therefore, it might be necessary to eliminate 100 percent of the threatening wheat proteins to prevent an autoimmune reaction.

Von Wettstein said the ultimate goal of his research group is to “obtain wheat that lacks the approximately 70 immunogenic proteins that causes the erasure of the epithelium in the intestine,” in people with celiac disease.

It’s difficult to assess how long it will take the scientists to develop a commercial variety of wheat because the wheat must be first tested on mice and human patients with celiac disease.

“As a serious scientist ,I don’t like to provide prognosis of the time when this aim is reached,” von Wettstein said.

More research will be needed to eliminate the problematic proteins, but Zemetra said the knowledge gained from the research might allow scientists to apply RNA interference to other aspects of wheat breeding.

“One of the avenues to look at, besides the modification of the wheat gene expression, is that it (offers) a lot of promise in the area of virus replication suppression,” he said. “Many of the plant viruses are RNA viruses, it basically sets the plant up to defend against the virus and prevents it from replicating.”

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