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Characterization of the binding site for d-deprenyl in human inflamed synovial membrane.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences. Med Univ Warsaw, Ctr Preclin Res & Technol, Dept Pharmacodynam, Warsaw, Poland.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
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2018 (English)In: Life Sciences, ISSN 0024-3205, E-ISSN 1879-0631, Vol. 194, p. 26-33Article in journal (Refereed) Published
Abstract [en]

Aims: D-Deprenyl when used as a positron emission tomography tracer visualizes peripheral inflammation. The major aim of the current study was to identify and investigate the properties of the binding target for D-deprenyl in synovial membrane explants from arthritic patients.

Main methods: Thirty patients diagnosed with arthritis or osteoarthritis were enrolled into the study. Homologous and competitive radioligand binding assays utilizing [H-3]D-deprenyl were performed to investigate the biochemical characteristics of the binding site and assess differences in the binding profile in synovial membranes exhibiting varying levels of inflammation.

Key findings: The [H-3]D-deprenyl binding assay confirmed the existence of a single, saturable population of membrane-bound protein binding sites in synovial membrane homogenates. The macroscopically determined level of inflammation correlated with an increase in [H-3]D-deprenyl binding affinity, without significant alterations in binding site density. Selective monoamine oxidase B inhibitor, selegiline competed for the same site as [H-3]D-deprenyl, but failed to differentiate the samples with regard to their inflammation grade. A monoamine oxidase A inhibitor, pirlindole mesylate showed only weak displacement of [H-3]D-deprenyl binding. No significant alterations in monoamine oxidase B expression was detected, thus it was not confirmed whether it could serve as a marker for ongoing inflammation.

Significance: Our study was the first to show the biochemical characteristics of the [H-3]D-deprenyl binding site in inflamed human synovium. We confirmed that d-deprenyl could differentiate between patients with varying severity of synovitis in the knee joint by binding to a protein target distinct from monoamine oxidase B.

Place, publisher, year, edition, pages
2018. Vol. 194, p. 26-33
Keywords [en]
Arthritis, Binding target, Monoamine oxidase B, Synovium, d-Deprenyl
National Category
Pharmaceutical Sciences
Research subject
Pharmaceutical Biochemistry; Medical Biochemistry
Identifiers
URN: urn:nbn:se:uu:diva-347601DOI: 10.1016/j.lfs.2017.12.003ISI: 000425052000004PubMedID: 29221756OAI: oai:DiVA.org:uu-347601DiVA, id: diva2:1195301
Funder
Swedish Research Council, 9459Available from: 2018-04-04 Created: 2018-04-04 Last updated: 2018-04-18Bibliographically approved
In thesis
1. Visualization of Peripheral Pain Generating Processes and Inflammation in Musculoskeletal Tissue using [11C]-D-deprenyl PET
Open this publication in new window or tab >>Visualization of Peripheral Pain Generating Processes and Inflammation in Musculoskeletal Tissue using [11C]-D-deprenyl PET
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

An objective visualization and quantification of pain-generating processes in the periphery would alter pain diagnosis and represent an important paradigm shift in pain research. Positron emission tomography (PET) radioligand [11C]-D-deprenyl has shown an elevated uptake in painful inflammatory arthritis and whiplash-associated disorder. However, D-Deprenyl’s molecular binding target and uptake mechanism in inflammation and musculoskeletal injuries are still unknown. The present thesis aimed to gain insight into the mechanisms of D-deprenyl binding and uptake and to verify whether pain-associated sites and inflammation in acute musculoskeletal injury could be visualized, objectively quantified and followed over time with [11C]-D-deprenyl PET-computed tomography (PET/CT).

To identify the D-deprenyl binding target, a high-throughput analysis and competitive radioligand binding studies were performed. D-deprenyl inhibited monoamine oxidase A (MAO-A) activity by 55%, MAO-B activity by 99% and angiotensin-converting enzyme (ACE) by 70%, which identified these enzymes as higher-affinity targets. Furthermore, radioligand receptor binding assays pointed favorably towards the concept of MAO-B as the primary target. To investigate the biochemical characteristics of the binding site, we used radioligand binding assays to assess differences in the binding profile in inflamed human synovial membranes exhibiting varying levels of inflammation. D-deprenyl bound to a single, saturable population of membrane-bound protein in synovial membrane homogenates and the level of inflammation correlated with an increase in D-deprenyl binding affinity.

To verify whether D-deprenyl can visualize pain-generating processes, patients with musculoskeletal injuries were investigated and followed-up with [11C]-D-deprenyl PET/CT. In the study of eight patients with ankle sprain, the molecular aspects of inflammation and tissue injury could be visualized, objectively quantified and followed over time with [11C]-D-deprenyl PET/CT. The pain coexisted with increased [11C]-D-deprenyl uptake. In the study of 16 whiplash patients, an altered [11C]-D-deprenyl uptake in the cervical bone structures and facet joints was associated with subjective pain levels and self-rated disability.

To further evaluate D-Deprenyl’s usefulness as a marker of inflammation, three PET tracers were compared in an animal PET/CT study. Preliminary findings showed that [11C]-D-deprenyl had an almost identical uptake pattern when compared with [11C]-L-deprenyl. The two deprenyl enantiomers showed no signs of specific binding or trapping and therefore may not be useful to study further in models of inflammatory pain, surgical pain, or both.

This thesis demonstrates that D-deprenyl visualizes painful inflammation in musculoskeletal injuries and that the probable underlying mechanism of [11C]-D-deprenyl uptake is binding to MAO.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2018. p. 72
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1456
Keywords
ankle injuries, arthritis, binding site, binding target, carbon-11, deprenyl, high-throughput screening, inflammation, monoamine oxi-dase, pain, PET, whiplash
National Category
Anesthesiology and Intensive Care Radiology, Nuclear Medicine and Medical Imaging
Research subject
Anaesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-347685 (URN)978-91-513-0313-0 (ISBN)
Public defence
2018-05-25, Universitetshuset, Biskopsgatan 3, Uppsala, 09:00 (Swedish)
Opponent
Supervisors
Available from: 2018-05-02 Created: 2018-04-06 Last updated: 2018-05-02

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Aarnio, MikkoNyberg, FredGordh, T

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