Treatment of both native and deamidated gluten peptides with an endo-peptidase from Aspergillus niger prevents stimulation of gut-derived gluten-reactive T cells from either children or adults with celiac disease

• Out of 25 proteases considered, only one was able to degrade gluten in vitro.
• A proline-specific protease from Aspergillus niger (AnP2) completely degraded gluten.
• Responses by gluten-reactive T cell lines from 3 adults and 4 children were abolished.
• Our study indicates a therapeutic benefit of AnP2 to CD patients.

Celiac disease (CD) is characterized by an inappropriate immunological reaction against gluten driven by gluten-specific CD4 + T cells. We screened 25 proteases and tested 10 for their potential to degrade gluten in vitro. Five proteases were further tested for their ability to prevent the proliferative response by a gluten-specific CD4 + T cell clone and seven gluten-reactive T cell lines to protease-digested gluten peptides. A proline-specific endo-peptidase from Aspergillus niger (AnP2) was particularly efficient at diminishing proliferation after stimulation with cleaved antigen, and could completely block the response against both native and deamidated gluten peptides. We found that AnP2 was efficient down to a 1:64 protease:substrate ratio (w:w). When AnP2 was tested in assays using seven gluten-reactive T cell lines from individual CD patients (three adults and four children), the response to gluten was diminished in all cases. Our study indicates a therapeutic benefit of AnP2 to CD patients.