Toxic Factor in Gluten Identified

Researchers have identified a 33-amino acid peptide, a breakdown product of gluten, which apparently triggers the autoimmune response in the small intestine that characterizes the syndrome called celiac sprue. Their findings were published in the September 27, 2002, issue of Science.

In vitro and in vivo studies in rats and humans demonstrated that the peptide was stable toward breakdown by all gastric, pancreatic, and intestinal brush-border membrane proteases. The only proteolytic enzyme that was found to degrade the peptide was a bacterial prolyl endopeptidase.

The peptide reacted with tissue transglutaminase, the major autoantigen in celiac sprue, with substantially greater selectivity than known natural substrates of this extracellular enzyme. It was a potent inducer of gut-derived human T cell lines from 14 of 14 celiac sprue patients. The peptide was found in all gluten-containing grains, but was not present in grains that do not contain gluten.

The study presents, "a combined chemical-physiological-immunological answer to the question: why is gluten toxic to a person with celiac sprue?” said senior author Dr. Chaitan Khosla from Stanford University (Palo Alto, CA, USA). "If proven correct, the findings will lead to new insights into the causes of celiac sprue, and perhaps certain other types of autoimmune diseases.”

The researchers believe that the bacterial endopeptidases, which were effective in human tissue cultures as well as living rats, may result in a simple, oral supplement that would alleviate the harmful effects of gluten. This treatment approach would be similar to enzyme supplements taken orally by those unable to digest lactose.



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