Background and aimsCoeliac disease (CD) is triggered by an abnormal reaction to gluten. Peptides resulting from partially digested gluten of wheat, barley or rye cause inflammation of the small intestinal mucosa. Previous contradictory studies suggest that oats may trigger the abnormal immunological response in patients with CD. Monoclonal antibodies (moAbs) against the main immunotoxic 33-mer peptide (A1 and G12) react strongly against wheat, barley and rye but have less reactivity against oats. The stated aim of this study is to test whether this observed reactivity could be related to the potential toxicity of oats for patients with CD.MethodsIn the present study, different oat varieties, controlled for their purity and by their distinct protein pattern, were used to examine differences in moAb G12 recognition by ELISA and western blot. Immunogenicity of oat varieties was determined by 33-mer concentration, T cell proliferation and interferon γ production.ResultsThree groups of oat cultivars reacting differently against moAb G12 could be distinguished: a group with considerable affinity, a group showing slight reactivity and a third with no detectable reactivity. The immunogenicity of the three types of oats as well as that of a positive and negative control was determined with isolated peripheral blood mononuclear T cells from patients with CD by measurement of cell proliferation and interferon γ release. A direct correlation of the reactivity with G12 and the immunogenicity of the different prolamins was observed.ConclusionsThe results showed that the reactivity of the moAb G12 is proportional to the potential immunotoxicity of the cereal cultivar. These differences may explain the different clinical responses observed in patients suffering from CD and open up a means to identify immunologically safe oat cultivars, which could be used to enrich a gluten-free diet.

A strict gluten-free diet (GFD) is the only currently available therapeutic treatment for patients with celiac disease (CD). Traditionally, treatment with a GFD has excluded wheat, barley and rye, while the presence of oats is a subject of debate. The most-recent research indicates that some cultivars of oats can be a safe part of a GFD. In order to elucidate the toxicity of the prolamins from oat varieties with low, medium, and high CD toxicity, the avenin genes of these varieties were cloned and sequenced, and their expression quantified throughout the grain development. At the protein level, we have accomplished an exhaustive characterization and quantification of avenins by RP-HPLC and an analysis of immunogenicity of peptides present in prolamins of different oat cultivars. Avenin sequences were classified into three different groups, which have homology with S-rich prolamins of Triticeae. Avenin proteins presented a lower proline content than that of wheat gliadin; this may contribute to the low toxicity shown by oat avenins. The expression of avenin genes throughout the development stages has shown a pattern similar to that of prolamins of wheat and barley. RP-HPLC chromatograms showed protein peaks in the alcohol-soluble and reduced-soluble fractions. Therefore, oat grains had both monomeric and polymeric avenins, termed in this paper gliadin- and glutenin-like avenins. We found a direct correlation between the immunogenicity of the different oat varieties and the presence of the specific peptides with a higher/lower potential immunotoxicity. The specific peptides from the oat variety with the highest toxicity have shown a higher potential immunotoxicity. These results suggest that there is wide range of variation of potential immunotoxicity of oat cultivars that could be due to differences in the degree of immunogenicity in their sequences.

SummaryWe have investigated the possible role of the metabolism of tryptophan and activity of the enzyme indoleamine 2,3-dioxygenase (IDO) in the immune regulation of coeliac disease (CD). Serum concentrations of tryptophan and its metabolites kinurenines were determined by high performance liquid chromatography in 24 patients with CD, seven patients with Crohn's disease and five healthy patients. We detected an increase of kynurenine (4·2 mmol/l Ϯ 0·27 versus 2·6 mmol/l Ϯ 0·54, P < 0002) and of the kynurenine/tryptophan ratio in supernatants of coeliac patients (11·5 mmol/ l Ϯ 1·01 versus 6·5 mmol/l Ϯ 1·57, P < 0005) in comparison with healthy patients, respectively, and we found no differences with Crohn's disease patients. Immunohistochemistry analysis of intestinal biopsies from CD patients showed an increased expression of IDO, interferon-g, interleukin-10 and transforming growth factor-b. Our data suggest that a mechanism(s) dependent on tryptophan catabolism might regulate the immune responses in CD.

Coeliac disease (CD) is a common autoimmune disorder characterized by an immune response to ingested gluten and has a strong HLA association with HLA-DQ2 and HLA-DQ8, but as human HLA-DQ risk factors do not explain the entire genetic susceptibility to gluten intolerance. Our aim was to investigate whether HLA-G, a gene located in the MHC class I region, and with important role in the induction of immunotolerance, may contribute to CD susceptibility. We demonstrated the expression of soluble HLA-G (sHLA-G) forms in intestinal biopsy and in serum of patients with CD. Indeed, all patients tested showed a positive expression of HLA-G in intestinal mucosa with different grade of immunoreaction. The serum levels of sHLA-G found in coeliac patients depend on the association with other diseases of autoimmune nature or genetics, and also depend on the transgressions in the diet with gluten ingested. The enhancer expression of sHLA-G in CD could be due as part of a mechanism to try restore the tolerance process towards oral antigens in a disease caused by loss of tolerance to dietary antigens and counteract the inflammation. In summary, in this paper, we demonstrate the association of CD with sHLA-G expression.

Scope The only treatment available for coeliac disease (CD) is a strict diet in which the intake of wheat, barley, rye, or oats is avoided. Barley is a major cereal crop, grown mainly for its use in brewing, and it has high nutritional value. The identification of varieties with a reduced toxicity profile may contribute to improve the diet, the quality of life and health of CD patients. Methods and results Searching for harmless barleys, we investigated accessions of malting and wild barley, used for developing new cultivated cereals. The CD toxicity profile of barleys was screened using G12 antibody and cell proliferation and IFN‐γ release from peripheral blood mononuclear cells and intestinal biopsies from CD patients. We found a direct correlation between the reactivity with G12 and the immunogenicity of the different barleys. Conclusion The malting barleys were less immunogenic, with reduced levels of toxic gluten, and were possibly less harmful to CD patients. Our findings could raise the prospect of breeding barley species with low levels of harmful gluten, and the attractive goal of developing nontoxic barley cultivars, always taking into account the Codex standard for foods for special dietary use for persons intolerant to gluten.