Grano duro più tollerabile per soggetti sensibili al glutine non celiaci

Lo scopo della ricerca “In search of tetraploid wheat accessions reduced in celiac disease-related gluten epitopes” è l’individuazione di accessioni di grano duro con la minore quantità di frazioni (epitopi) che attivano la risposta avversa del sistema immunitario dell’uomo nella celiachia e non solo.
I grani con una minore quantità di queste frazioni (epitopi) potrebbero aiutare quei soggetti celiaci ancora non diagnosticati (circa il 95% di tutti i pazienti CD): “che consumano quotidianamente proteine del glutine stimolanti la celiachia senza rendersi conto del suo effetto sulla loro salute e benessere”.
I grani individuati pur non essendo idonei per i soggetti celiaci possono “contribuire a ritardare o addirittura prevenire l’insorgenza della celiachia e lo sviluppo dei suoi sintomi in quella parte del popolazione geneticamente suscettibile, specialmente nei bambini (van den Broeck et al.), perché la quantità di epitopi, presenti nei prodotti contenenti glutine consumati è un fattore importante che può influenzare la rappresentazione clinica della celiachia, insieme ad altri fattori riconosciuti come il tipo di latte vaccino, l’omissione dell’allattamento al seno e l’età per l’introduzione del glutine”.
La ricerca ha esaminato il glutine di “103 tetraploid wheat accessions (obtained from the Dutch CGN genebank and from the French INRA collection) including landraces, old, modern, and domesticated accessions of various tetraploid species and subspecies from many geographic origins. Those accessions were typed for their level of T-cell stimulatory epitopes.” La ricerca ha evidenziato l’esistenza di “ 8 CGN and 6 INRA accessions with reduced epitope staining.”
…omissis “Tetraploid wheats contain less T-cell stimulatory a-gliadin epitopes than hexaploid bread wheat because of the absence of the D-genome. The highly immunodominant T-cell stimulating 33-mer is exclusively present in a-gliadins encoded by the D-genome (bread wheat). In addition, the levels of T-cell stimulatory epitopes have been shown to vary among varieties (van den Broeck et al. ). This opens possibilities to select for wheat varieties with significantly reduced a-gliadin epitope levels, aiming at direct use or to apply in breeding programs directed towards large-scale reduction or even total elimination of CD-stimulating gluten-elements from wheat.”

Note
Dallo studio:
“A landrace may be a mixture of genotypes, which evolved under the environmental conditions where they were grown because of natural selection and selection by the farmer. Tetraploid wheat can mix up with hexaploid bread wheat very easily under agricultural conditions and care should be taken if the tetraploid wheat should be maintained as a pure genotype. As a result, many commercial lots, currently sold as durum wheat, nearly always contain some hexaploid bread wheat.”

“Differences among wheat varieties in gluten proteins occur because of allelic variation (genotype) that determines the gluten protein composition. The approach we used in this study analyzes this genotypic variation by comparing the same amount of gluten protein per accession. Changes in gluten protein composition have been described, but are mainly expected if growth conditions are extreme (high or low temperature, dry or wet conditions). The varieties and accessions we have analyzed were grown under normal wheat growth conditions and therefore, their influence on the gluten protein composition is not expected.”

“The occurrence of different genotypes and even different ploidy levels in a single genebank accession is a complicating phenomenon for genebank managers to accurately characterize landraces. Many landraces often result from maintenance and selection practices by local farmers directed towards optimizations to local agronomic and food applications. As a consequence, genebank passport data turned out to be poor predictors of the real genetic composition of landrace accessions that may be mixtures of genotypes of tetraploid and even hexaploid wheat species. “

In search of tetraploid wheat accessions reduced in celiac disease-related gluten epitopes. Hetty van den Broeck et al.
www.rsc.org/molecularbiosystems. July 2010 DOI: 10.1039/c0mb00046a

Keywords: grano duro, grano meno tossico, immunogenicità del grano, predisposizione alla celiachia, varietà grano duro più tollerabili, proteine del glutine