Wednesday, 2 November 2011

Diversity in oat potential immunogenicity: basis for the selection of oat varieties with no toxicity in coeliac disease


Results of a study conducted in Spain by Professor Carolina Sousa, Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, C/Profesor García González, no. 2, Sevilla 41012, Spain; csoumar@us.es
  1. Abstract

    Background and aims Coeliac 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.
    Methods In 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.
    Results Three 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.
    Conclusions The 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.
    This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited, the use is non commercial and is otherwise in compliance with the license. 


    Contributors Conceived and designed the experiments: CI, TM, CA, SC. Performed the experiments: CI, RA, LL, LAM, BF, LP. Analysed the data: CI, LL, TM, CA, SC. Contributed reagents/materials/analysis tools: CH, LAM, BF, CA, CS. Wrote the paper: CI, LL, BF, TM, CA, SC.

Baked Pumpkin Oatmeal


From The Baking Beauties (source link)           
Ingredients:
  • 1/2 cup pumpkin puree (not pie filling)
  • 1 egg
  • 1/3 cup maple syrup
  • 1 tsp vanilla
  • 2/3 cup milk of your choice
  • 1 tsp ground cinnamon
  • 1/2 tsp ground ginger
  • 1/4 tsp fresh ground nutmeg
  • 1/2 tsp salt
  • 2 cups GF oats
  • 1 1/2 tsp baking powder
  • 1/2 cup chopped pecans (optional)
Directions:
  1. Preheat oven to 180 o C
  2. Lightly grease an 8×8-inch square baking pan. Set aside.
  3. In a large bowl, combine all ingredients.
  4. Pour into lightly greased baking sheet, and bake in preheated oven for 30-35 minutes. Let sit for 5 minutes before serving. This would be great topped with some ice cream or whipped cream too.

    Order your GF Oats here in Australia

Should Coeliacs Eat Oats? It Depends on the Oat.

Gut Health and Coeliac Disease

Gut health and coeliac disease

It is still a matter of controversy whether or not oats are safe for people with coeliac disease. The general consensus at this point seems to be that pure oats are safe for most, but not all, people with coeliac. Since oats can easily be contaminated with wheat during harvest, storage, or other stages of processing, it has been stressed that the oats be certified as pure. Although the classic 33-amino acid long oligopeptide that acts as the immunogenic stimulus in gliadin had not yet been found in oats, other peptides isolated from oats do activate T-cells isolated from coeliac patients. A new study performed in Spain by Isabel Comino et al. suggests that it is not that some coeliac patients can’t tolerate all oats, but rather that all coeliac patients can’t tolerate some oats. Their results are reported in the January 2011 issue of GUT: An International Journal of Gastroenterology and Hepatology.

Dr. Comina and her colleagues examined nine different cultivars of oats. They exposed each of them to a sensitive monoclonal antibody generated to recognize the toxic 33-mer from gliadin, and also measured if each of the oat varieties could elicit an immune response in peripheral blood mononuclear cells from coeliac patients. They wanted to see if they could correlate recognition by the monoclonal antibody to induction of a T-cell response, and found that they certainly could.

The nine varieties of oats segregated neatly into three groups of three varieties each: those for which the antibody had high affinity, low affinity, and no affinity. This affinity was validated by two different experimental methods, so was not an artifact of the technique chosen. When T cells from patients with coeliac were exposed to extracts of the oat variety the antibody bound to strongest, they proliferated the most and released interferon-gamma, an immunostimulatory cytokine whose aberrant expression is associated with autoinflammatory disease. In contrast, the oats that didn’t react with the antibody did not elicit these immune responses. The authors note that the avenin – the storage protein in oats – from even the most immunogenic oats they saw bound to this antibody with 40-400 fold less affinity than gliadin (from gluten – the storage protein in wheat).

This study thus leaves us with two valuable conclusions. One is that some oats are more toxic than others, regardless of their purity. And the other is that reactivity with this antibody can be correlated to toxicity, making it a potential tool for evaluating the toxic gluten content of other food.

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