Plant science and the gluten-free diet

How do you make gluten-free bread? From gluten-free wheat, obviously.

AoB Blog welcomes the return of guest author, Charlie Haynes, who is currently a final year student in the School of Biological Sciences at the University of Leicester.

Gluten free For around ten thousand years cereals have been a staple component of human diets. They are ubiquitous, with a cultural and religious significance to many. They permeate our diet. But the component that makes wheat so perfect for making bread dough, with its stretchy, elastic consistency, can also elict a severe autoimmune response for sufferers of coeliac disease.

Gluten proteins split into two subgroups; gliadin (soluble) and glutenin (insoluble), with gliadin proteins contributing the majority of epitopes associated with coeliac disease. The autoimmune reaction results in inflammation of the small bowel resulting in a damaging of the gut lining and vitamin malabsorption. Untreated it can lead to a quadrupling in mortality. And there has been a dramatic increase in prevalence of undiagnosed coeliac disease, with around 1 in 100 people in the UK now affected.

The only current treatment for coeliac disease is strict adherence to a gluten-free diet which is tricky. Gluten permeates the western diet, and there is evidence to suggest that a gluten free diet isn’t the shining beacon of health purported by health magazines. It can be high in fat, and deficient in iron, folate and calcium. Once patients are on a gluten free diet they often put on weight.

But not all gluten proteins contain the allergenic stimulatory epitopes. Various groups have been trying to decrease these epitopes whilst maintaining the technical properties important in bread making. Broeck et al investigated the effect of deleting individual gene loci in Triticum aestivum or chinese spring, the first wheat variety to have its genome sequenced. They were able to identify the specific gliadins that could remove stimulatory epitopes whilst maintaining structural properties (the ω-gliadin, γ-gliadin, and LMW-GS loci from the short arm of chromosome 1 of the D-genome, 1DS).

Barro et al were able to go further using RNA interference (a method of using RNA to prevent gene expression by destroying specific mRNA sequences) to down regulate expression of these gliadins. Gluten extracts from three of these transgenic lines samples were unable to elicit T cell responses and six others caused reduced responses.

This is groundbreaking work for coeliac patients. It means that we are coming closer to being able to marginalise the effect of coeliac disease in the day to day life of sufferers. Being able to have coeliac specialised wheat without any loss of technical properties will make it much easier for sufferers to enjoy more foods, and live more fulfilled, healthier lives.