A food-grade enzyme preparation with modest gluten detoxification properties.
OBJECTIVE
Celiac sprue is a life-long disease characterized by an intestinal inflammatory response to dietary gluten. A gluten-free diet is an effective treatment for most patients, but accidental ingestion of gluten is common, leading to incomplete recovery or relapse. Food-grade proteases capable of detoxifying moderate quantities of dietary gluten could mitigate this problem.


METHODS
We evaluated the gluten detoxification properties of two food-grade enzymes, aspergillopepsin (ASP) from Aspergillus niger and dipeptidyl peptidase IV (DPPIV) from Aspergillus oryzae. The ability of each enzyme to hydrolyze gluten was tested against synthetic gluten peptides, a recombinant gluten protein, and simulated gastric digests of whole gluten and whole-wheat bread. Reaction products were analyzed by mass spectrometry, HPLC, ELISA with a monoclonal antibody that recognizes an immunodominant gluten epitope, and a T cell proliferation assay.


RESULTS
ASP markedly enhanced gluten digestion relative to pepsin, and cleaved recombinant alpha2-gliadin at multiple sites in a non-specific manner. When used alone, neither ASP nor DPPIV efficiently cleaved synthetic immunotoxic gluten peptides. This lack of specificity for gluten was especially evident in the presence of casein, a competing dietary protein. However, supplementation of ASP with DPPIV enabled detoxification of moderate amounts of gluten in the presence of excess casein and in whole-wheat bread. ASP was also effective at enhancing the gluten-detoxifying efficacy of cysteine endoprotease EP-B2 under simulated gastric conditions.


CONCLUSIONS
Clinical studies are warranted to evaluate whether a fixed dose ratio combination of ASP and DPPIV can provide near-term relief for celiac patients suffering from inadvertent gluten exposure. Due to its markedly greater hydrolytic activity against gluten than endogenous pepsin, food-grade ASP may also augment the activity of therapeutically relevant doses of glutenases such as EP-B2 and certain prolyl endopeptidases.
Ehren
Jennifer
J
Department of Chemical Engineering, Stanford University, Stanford, CA, USA.
Morón
Belen
B
Martin
Edith
E
Bethune
Michael T
MT
Gray
Gary M
GM
Khosla
Chaitan
C
D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D018819:Dipeptidyl Peptidase 4 / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005502:Food; D005983:Glutens / Q000737:chemistry / Q000378:metabolism*; D006868:Hydrolysis; D013058:Mass Spectrometry; D008969:Molecular Sequence Data
D005983:Glutens; D018819:Dipeptidyl Peptidase 4