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.

Department of Biochemistry and Molecular Biology and the Southern Alberta Cancer Research Institute University of Calgary Calgary Alberta Canada

Farncombe Family Digestive Health Research Institute McMaster University Hamilton ON Canada

Graz University of Technology Institute of Molecular Biotechnology Graz Austria

Institute of Microbiology Academy of Sciences of the Czech Republic and Department of Biochemistry Faculty of Science Charles University Prague Prague Czech Republic

Structural Mass Spectrometry and Proteomics Unit Institut Pasteur CNRS UMR 3528 Paris France

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Sci Rep. 2023 Jan 18;13(1):956. doi: 10.1038/s41598-023-28196-w. PubMed

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