Can prolyl endopeptidase reduce the IgE-reactivity of gluten proteins?

Background

Coeliac disease and IgE-mediated allergy to wheat are immune-mediated conditions which are thought to be triggered by digestion-resistant wheat proteins. Recently, a prolyl endopeptidase from Aspergillus niger (AnPEP) has been identified as being able to accelerate breakdown of gluten in food using an in vitro digestion system. Such digests have been analysed in terms of coeliac disease t-cell epitope levels[1] but have not yet been considered regarding the impact on IgE-reactivity. The amount of AnPEP required to be effective also has yet to be investigated.

Methods

We have used an in vitro batch gastric digestion model to break down a bread matrix with different amounts of AnPEP. SDS PAGE and immunoblots have been used to monitor protein digestion, and mass spectrometry has allowed for epitopes important to IgE-mediated wheat allergy and coeliac disease to be tracked. Sera were obtained from a Spanish patient panel with allergy to wheat induced by exercise and/or NSAIDs and used for additional immunoblots.

Results

SDS PAGE and immunoblotting with anti-gluten antibodies show more effective breakdown of gliadins and LMW glutenins in the presence of AnPEP. The impact of digestion on the IgE-reactivity of gluten by immunoblotting has been correlated with resistant proteins and peptides mapped by mass spectrometry. Use of 200 mg AnPEP/ g substrate showed the largest difference in digestion kinetics of gluten proteins however increased breakdown was still visible using 20 mg AnPEP/ g substrate.

Conclusions

AnPEP alters the patterns and pathways of gluten in a simulated gastroduodenal digestion system. The potential application of such enzymes to modify the allergenic potential of cereals is discussed.