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Yazbeck R, Jaenisch S, Squire M, Abbott CA, Parkinson-Lawrence E, Brooks DA, Butler RN. Development of a 13C Stable Isotope Assay for Dipeptidyl Peptidase-4 Enzyme Activity A New Breath Test for Dipeptidyl Peptidase Activity. Sci Rep 2019; 9:4906. [PMID: 30894647 PMCID: PMC6427020 DOI: 10.1038/s41598-019-41375-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 03/07/2019] [Indexed: 01/15/2023] Open
Abstract
Dipeptidyl peptidase-4 inhibitors (DPP4i) are a class of orally available, small molecule inhibitors for the management of Type-II diabetes. A rapid, real-time, functional breath test for DPP4 enzyme activity could help to define DPP4i efficacy in patients that are refractory to treatment. We aimed to develop a selective, non-invasive, stable-isotope 13C-breath test for DPP4. In vitro experiments were performed using high (Caco-2) and low (HeLa) DPP4 expressing cells. DPP gene expression was determined in cell lines by qRT-PCR. A DPP4 selective 13C-tripeptide was added to cells in the presence and absence of the DPP4 inhibitor Sitagliptin. Gas samples were collected from the cell headspace and 13CO2 content quantified by isotope ratio mass spectrometry (IRMS). DPP4 was highly expressed in Caco-2 cells compared to HeLa cells and using the 13C-tripeptide, we detected a high 13CO2 signal from Caco2 cells. Addition of Sitaglitpin to Caco2 cells significantly inhibited this 13CO2 signal. 13C-assay DPP4 activity correlated positively with the enzyme activity detected using a colorimetric substrate. We have developed a selective, non-invasive, 13C-assay for DPP4 that could have broad translational applications in diabetes and gastrointestinal disease.
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Affiliation(s)
- Roger Yazbeck
- College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia. .,Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, South Australia, Australia.
| | - Simone Jaenisch
- College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia.,Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, South Australia, Australia
| | - Michelle Squire
- College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Catherine A Abbott
- Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, South Australia, Australia.,College of Science and Engineering, Flinders University, Adelaide, South Australia, Australia
| | - Emma Parkinson-Lawrence
- School of Pharmacy and Medical Science, University of South Australia Cancer Research Institute, Adelaide, South Australia, Australia
| | - Douglas A Brooks
- School of Pharmacy and Medical Science, University of South Australia Cancer Research Institute, Adelaide, South Australia, Australia.,School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Ross N Butler
- College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia.,School of Pharmacy and Medical Science, University of South Australia Cancer Research Institute, Adelaide, South Australia, Australia
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