Addressing proteolytic efficiency in enzymatic degradation therapy for celiac disease.

Celiac disease is triggered by partially digested gluten proteins. Enzyme therapies that complete protein digestion in vivo could support a gluten-free diet, but the barrier to completeness is high. Current options require enzyme amounts on the same order as the protein meal itself. In this study, we evaluated proteolytic components of the carnivorous pitcher plant (Nepenthes spp.) for use in this context. Remarkably low doses enhance gliadin solubilization rates, and degrade gliadin slurries within the pH and temporal constraints of human gastric digestion. Potencies in excess of 1200:1 (substrate-to-enzyme) are achieved. Digestion generates small peptides through nepenthesin and neprosin, the latter a novel enzyme defining a previously-unknown class of prolyl endoprotease. The digests also exhibit reduced TG2 conversion rates in the immunogenic regions of gliadin, providing a twin mechanism for evading T-cell recognition. When sensitized and dosed with enzyme-treated gliadin, NOD/DQ8 mice did not show intestinal inflammation, when compared to mice challenged with only pepsin-treated gliadin. The low enzyme load needed for effective digestion suggests that gluten detoxification can be achieved in a meal setting, using metered dosing based on meal size. We demonstrate this by showing efficient antigen processing at total substrate-to-enzyme ratios exceeding 12,000:1.YesThis work was supported by the University of Calgary and by a grant to DCS from the Canadian Celiac Association. EFV holds a Canada Research Chair and is funded by CIHR MOP#142773. PM, HM and PH were supported by MEYS (LO1509) and EU (CZ.1.05/1.1.00/02.0109). We thank Drs. Chella David and Joseph Murray of the Mayo Clinic for kindly providing the original breeding pairs of SPF NOD AB?DQ8 (NOD/DQ8) mice. We thank Luppo Edens of DSM Food Specialties (Netherlands) for the gift of AN-PEP. We thank Brent Schriemer, Laurent Brechenmacher and the Urban Bog for technical support