Researchers tested serum samples of 120 individuals, including 50 patients with biopsy-proven celiac disease, 20 patients with the associated rash dermatitis herpetiformis and 50 unaffected controls for reaction levels of antibodies (IgG and IgA) considered highly specific and sensitive to celiac disease. They tested this with non-gluten proteins extracted from the common wheat Triticum aestivum.
According to the research published in the American Chemical Society’s Journal of Proteome Research, celiac patients showed significantly higher levels of antibody reactivity to non-gluten proteins compared to the healthy control participants.
Five groups of non-gluten proteins caused immune reactions in the dermatitis herpetiformis and celiac groups: purinin, α-amylase/protease inhibitor, globulin, and farinin proteins, while the most reactive non-gluten antigen identified was a serpin protein.
Celiac disease symptoms can occur when wheat, rye or barley is eaten by sufferers of the condition and has therefore been put down to the gluten protein group the grains have in common – and which make up about 75% of all proteins in wheat.
The only treatment for the disease is to avoid gluten-containing foods, but the researchers behind this study from Columbia University, the University of Padova in Italy, University of Utah and the US Department of Agriculture said this has meant non-gluten proteins have largely been ignored as a possible trigger.
The researchers said a few earlier studies had attempted to assess immune reactivity to non-gluten proteins of wheat 22-26 with a small number of celiac patients, but results were inconsistent and the purity of the non-gluten protein extracts used to detect the immune reactivity was later questioned.
The researchers said their methodology provided "unequivocal confirmation" that the proteins targeted were not gluten, and therefore their new findings worked towards an understanding of how the disease worked as well as possible future treatments and diagnosis.
"While direct conclusions cannot be drawn about the pathogenic effects of the identified non-gluten proteins, these findings should prompt further research into their potential role in contributing to the inflammatory processes that result in mucosal damage in patients with celiac disease. The possibility of such a role for these proteins is worthy of attention, especially as therapies other than gluten exclusion from the diet are under development," they wrote.
Source: Journal of Proteome Research
Published online ahead of print, DOI: 10.1021/pr500809b
“Specific Non-Gluten Proteins of Wheat are Novel Target Antigens in Celiac Disease Humoral Response”
Authors: S. Huebener, C. K. Tanaka, M. Uhde, J. J. Zone, W. H. Vensel, D. D. Kasarda, L. Beams, C. Briani, P. H. R. Green, S. B. Altenbach and A. Alaedini