Alternative enzymes that can break down gluten are derived from germinating barley and the fungus Aspergillus niger. From the latter a prolyl endoprotease termed Aspergillus niger-derived prolyl endoprotease (AN-PEP) is derived which has distinct advantages selleck screening library over the bacterial prolyl oligopeptidase as it degrades both whole gluten and gluten peptides into non-immunogenic residues within minutes[11,12]. Moreover, the enzyme is active between pH 2 and pH 8, with an optimum activity at pH 4-5, and is therefore effective at the pH levels present in the stomach and beyond[11,13]. Importantly, the enzyme is not degraded by pepsin in the stomach and thus remains fully functional. Mitea et al[12] extended these findings by showing that AN-PEP degraded toxic gluten proteins in a food matrix into non-immunogenic gluten fragments in an in vitro digestion model that simulates the human gastrointestinal tract.

After these promising in vitro results, it remains to be established in CD patients whether AN-PEP can reduce the clinical response to gluten. The aim of this two-phase proof of concept study was to demonstrate the safety of AN-PEP in the first phase and the ability of ANPEP to reduce antibody and histological response to gluten consumption by CD patients in the second phase of the study. This information will be important to further develop AN-PEP as a future digestive aid for unintentional ingestion of gluten by CD patients. MATERIALS AND METHODS Patients Sixteen adults with CD were recruited at the outpatient clinic of the department of Gastroenterology and Hepatology of the VU Medical Centre Amsterdam, The Netherlands.

Inclusion criteria were an initial diagnosis of CD as confirmed by histological abnormalities on duodenal biopsies classified as a Marsh IIIB or IIIC lesion and supported by positive serology; endomysium IgA antibodies (IgA-EM) and/or tissue transglutaminase IgA antibodies (IgA-tTG). Patients were required to have well-controlled CD as evidenced by Marsh 0 or I, and normalised IgA-EM and IgA-tTG on a strict GFD for at least one year. Women at fertile age were required to take adequate contraception measures. Reasons for exclusion were: use of any anticoagulant or immunoregulatory drug within the last 6 mo; clinically suspected bleeding tendency; pregnancy or breast feeding; presence of any concurrent active infection; and IgA deficiency.

Design and intervention The intervention was performed Anacetrapib between May 2008 and April 2009. The intervention consisted of two periods, each lasting 2 wk (Figure (Figure1).1). The first study phase was an open-label period designed to assess the safety of high gluten intake with AN-PEP (safety phase). The second phase was a randomised, double-blind, placebo-controlled parallel-group study to assess the effect of AN-PEP on gluten-induced clinical response (efficacy phase). Sixteen patients with diagnosed CD were enrolled in the safety phase.