Antibodies to the wheat storage globulin Glo-3A in children before and at diagnosis of celiac disease

Protein quantification and enzyme activity estimation of Pakistani wheat landraces

Wheat is a major food grain in Pakistan having a prominent role in agriculture as well as the economic status of the country. In the current study, seeds of 99 wheat landraces were characterized for the quantification of seed storage proteins (Albumins, Globulin, Gliadins, and Glutenin), enzyme activities of antioxidant enzymes i.e. Ascorbate peroxidase (APX), Catalase (CAT), Superoxide dismutase (SOD), Peroxidase (POD), one hydrolytic enzyme Protease (PROT) and non-enzymatic antioxidant enzyme Ascorbic acid (AsA). The landraces were categorized into low, medium, and high based on protein concentration and enzymes activities/content. The majority of the landraces were placed in the medium category. However, for the AsA parameter majority of the landraces were placed in the low category. The highest concentration of total extracted protein (184.88±0.7 mg/g. wt.), globulins (21.35±0.43 mg/g. wt.) and glutenin (20±0.04 mg/g. wt.) as well as the high activity of SOD (303±16.80 Units/g. wt.), and Ascorbic acid (533±36.1 Units/g. wt.) was identified in the wheat landrace "11757" collected from district Panjgur (Balochistan). The wheat landrace "11760", collected from district Kech (Balochistan), contained the highest albumins concentration (65.42±0.02 mg/g. wt.) and highest activity for CAT (589.5±61.20 Units/g. wt.). The highest activity of POD (32341± 91.3) and PROT was observed in seeds of the wheat landrace "11618" collected from the Gilgit Baltistan region of Pakistan. The principal component analysis showed that the great variations existed for the tested parameters among the wheat landraces. The landraces with a high concentration of seed storage proteins and antioxidant enzyme activities can be used for breeding purposes to improve the nutrimental quality of wheat cultivars.

Characterization of globulin storage proteins of a low prolamin cereal species in relation to celiac disease

Brachypodium distachyon, a small annual grass with seed storage globulins as primary protein reserves was used in our study to analyse the toxic nature of non-prolamin seed storage proteins related to celiac disease. The main storage proteins of B. distachyon are the 7S globulin type proteins and the 11S, 12S seed storage globulins similar to oat and rice. Immunoblot analyses using serum samples from celiac disease patients were carried out followed by the identification of immune-responsive proteins using mass spectrometry. Serum samples from celiac patients on a gluten-free diet, from patients with Crohn’s disease and healthy subjects, were used as controls. The identified proteins with intense serum-IgA reactivity belong to the 7S and 11–12S seed globulin family. Structure prediction and epitope predictions analyses confirmed the presence of celiac disease-related linear B cell epitope homologs and the presence of peptide regions with strong HLA-DQ8 and DQ2 binding capabilities. These results highlight that both MHC-II presentation and B cell response may be developed not only to prolamins but also to seed storage globulins. This is the first study of the non-prolamin type seed storage proteins of Brachypodium from the aspect of the celiac disease.

The next big idea

George S. Eisenbarth will remain in our memories as a brilliant scientist and great collaborator. His quest to discover the cause and prevention of type 1 (autoimmune) diabetes started from building predictive models based on immunogenetic markers. Despite his tremendous contributions to our understanding of the natural history of pre-type 1 diabetes and potential mechanisms, George left us with several big questions to answer before his quest is completed.

Seed storage proteins of the globulin family are cleaved post-translationally in wheat embryos

Background

The 7S globulins are plant seed storage proteins that have been associated with the development of a number of human diseases, including peanut allergy. Immune reactivity to the wheat seed storage protein globulin-3 (Glo-3) has been associated with the development of the autoimmune disease type 1 diabetes in diabetes-prone rats and mice, as well as in a subset of human patients.

Findings

The present study characterized native wheat Glo-3 in salt-soluble wheat seed protein extracts. Glo-3-like peptides were observed primarily in the wheat embryo. Glo-3-like proteins varied significantly in their molecular masses and isoelectric points, as determined by two dimensional electrophoresis and immunoblotting with anti-Glo-3A antibodies. Five major polypeptide spots were identified by mass spectrometry and N-terminal sequencing as belonging to the Glo-3 family.

Conclusions

These results in combination with our previous findings have allowed for the development of a hypothetical model of the post-translational events contributing to the wheat 7S globulin profile in mature wheat kernels.

Antibodies from a patient with type 1 diabetes and celiac disease bind to macrophages that express the scavenger receptor CD163

Antibodies against the wheat storage globulin Glo-3A from a patient with both type 1 diabetes (T1D) and celiac disease were enriched to identify potential molecular mimicry between wheat antigens and T1D target tissues. Recombinant Glo-3A was used to enrich anti-Glo-3A immunoglobulin G antibodies from plasma by batch affinity chromatography. Rat jejunum and pancreas, as well as human duodenum and monocytes were probed, and binding was evaluated by immunohistochemistry and confocal microscopy. Glo-3A-enriched antibodies bound to a specific subset of cells in the lamina propria of rat jejunum that co-localized mostly with a marker of resident, alternatively activated CD163-positive (CD163⁺) macrophages. Blood monocytes and macrophage-like cells in human duodenum were also labelled with the enriched antibodies. Blocking studies revealed that binding to CD163⁺ macrophages was not due to cross-reactivity with anti-Glo-3A antibodies, but rather to non-Glo-3A antibodies co-purified during antibody enrichment. The novel finding of putative autoantibodies against tolerogenic intestinal CD163⁺ macrophages suggests that regulatory macrophages were targeted in this patient with celiac disease and T1D.