Mitea C et al. (2008) Efficient degradation of gluten by a prolyl endoprotease in a gastrointestinal model: implications for coeliac disease. Gut 57: 25–32

A lifelong gluten-free diet effectively cures celiac disease, but compliance is difficult. Oral supplementation with nonhuman prolyl oligopeptidases (which cleave gluten proteins at proline residues and destroy their immunostimulatory properties) had long been proposed as a therapy for celiac disease, but most available enzymes did not function at gastric pH, and were efficiently degraded by pepsin. Aspergillus niger endoprotease (AN-PEP) does not have these drawbacks; however, its proteolytic properties have not been tested in vivo.

Mitea and colleagues have now tested AN-PEP in a computerized, mechanical system designed to simulate digestion in the human stomach and small intestine. They used data from healthy volunteers to model digestion in young adults after ingestion of a simple meal (white bread and water) and a complex fast-food meal (bread, hamburger, ketchup, French fries and soda), respectively. The researchers simulated digestion of each meal in the presence or absence of 200 mg AN-PEP, and analyzed samples taken at various time points from the stomach, duodenal, jejunal and ileal compartments.

AN-PEP completely degraded the gluten present in both meals within 2 h (the average time for passage of food through the stomach), which greatly reduced the amount of T-cell-stimulatory epitopes derived from gliadins and glutenins that reached the duodenal compartment.

The authors note that gluten might be degraded even faster in vivo than in their system, which lacked proteolytic brush border enzymes. They call for clinical trials to determine whether oral AN-PEP supplementation can completely detoxify gluten.