title: Can the Direct Peptide Reactivity Assay Be Used for the Identification of Respiratory Sensitization Potential of Chemicals?
abstract: Prospective identification of low molecular weight respiratory sensitizers is difficult due to the current lack of adequate test methods. The direct peptide reactivity assay (DPRA) seems to be a promising method to determine the sensitization potential of chemicals because it determines the intrinsic characteristic of sensitizers to bind to proteins. It is already applied in the field of skin sensitization, and adaptation to respiratory sensitization has started recently. This article further evaluates the ability of the DPRA to predict the respiratory sensitization potential of chemicals. In addition, the added value of applying High Performance Liquid Chromatography (HPLC)-MS and measurements after 20 minutes and 24 hours of incubation was evaluated. Eighteen respiratory sensitizers (10 haptens, 3 prehaptens, and 5 prohaptens) and 14 nonsensitizers were tested with 2-model peptides. Based on peptide depletion, a prediction model was proposed for the identification of (respiratory) sensitizers. Application of mass spectrometry and measurements at 2 time-points increased prediction accuracy of the assay by resolving discordant results. The prediction model correctly identified all haptens and prehaptens as sensitizers. The 5 prohaptens were not identified as sensitizers, most likely due to lack of metabolic activity in the DPRA. All but 1 nonsensitizer was correctly predicted. The model, therefore, shows an accuracy of 78% for the tested dataset. Unfortunately, this assay cannot be used to distinguish respiratory from skin sensitizers. To make this distinction, the DPRA needs to be combined with other test methods that are able to identify respiratory sensitizers.
authors.affiliation: *Centre for Health Protection Department of Toxicogenomics, Maastricht University, Maastricht 6200 MD, The Netherlands.
authors.forename: Sander
authors.initials: S
authors.lastname: Dik
authors.affiliation: Centre for Safety of Substances and Products, National Institute for Public Health and the Environment, Bilthoven 3720 BA, The Netherlands;
authors.forename: Emiel
authors.initials: E
authors.lastname: Rorije
authors.affiliation: *Centre for Health Protection.
authors.forename: Paul
authors.initials: P
authors.lastname: Schwillens
authors.affiliation: *Centre for Health Protection Department of Toxicogenomics, Maastricht University, Maastricht 6200 MD, The Netherlands.
authors.forename: Henk
authors.initials: H
authors.lastname: van Loveren
authors.affiliation: *Centre for Health Protection Janine.ezendam@rivm.nl.
authors.forename: Janine
authors.initials: J
authors.lastname: Ezendam
mesh_terms: D002851:Chromatography, High Pressure Liquid; D013058:Mass Spectrometry; D008962:Models, Theoretical; D010455:Peptides / Q000737:chemistry*; D012137:Respiratory System / Q000187:drug effects*; D018675:Toxicity Tests
chemical_list: D010455:Peptides
keywords: DPRA; alternatives to animal testing; asthma; predictive toxicology; respiratory sensitization