AB0106 CHANGES IN THE MIRNA PROFILE AND HYPOXIC BEHAVIOUR OF HUMAN CHONDROCYTES BY THERAPEUTIC NUCLEAR MAGNETIC RESONANCE THERAPY (NMRT)
Authors: Birgit Lohberger, Lukas Weigl, Nicole Stuendl, Anda Mann, Andreas Leithner, Werner Kullich, Bibiane Steinecker-Frohnwieser
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background:</h3> Therapeutically applied nuclear magnetic resonance (NMRT) is discussed to participate in repair processes regarding cartilage and influences pain signaling. Studies concerning NMR therapy implemented within the treatment of patients with degenerative rheumatic diseases outlined pain reduction as the main clinical outcome (1). NMRT is also known to lead to improvements in pain from patients with knee OA due to a chondroprotective effect on the articular cartilage. In spite of this significant reduction in pain, the mechanism of action of NMRT at the cellular level remains to be elucidated. <h3>Objectives:</h3> To substantiate the application of NMRT the aim of this work targets the underlying mechanisms at the cellular level. We investigated NMRT induced changes of the miRNA profile of human healthy and OA chondrocytes and studied the respective miRNA targets. Based on the fact that articular cartilage functions as an avascular and hypoxic connective tissue we were further able to demonstrate that NMRT modulation seems to be more pronounced under hypoxic conditions. <h3>Methods:</h3> Human primary chondrocytes and the chondrocyte cell line Tc28/2a were used for the experiments. RNA was extracted using RNEasy Mini Kit and was used as input for the Thermo Fisher Ion Total RNA-Seq Kit v2. Sequencing was performed on Ion Proton sequencer using the Ion PI Hi-Q™ Sequencing 200 system. Signal processing and base calling was performed using Torrent Suite version 5.6. Hypoxic conditions were established and enabled cell growth in presence of 1-5% O2. Expression of miRNAs and target proteins was studied by a standard PCR procedure as well as protein detection by western blot. HDAC activity was measured by HDAC-Glo I/II assay. <h3>Results:</h3> Characterization of the miRNA profile showed a slight up regulation of miR-24-1-5p and miR-502-5p while miR-25-5p and miR-365a-5p was down regulated. For miR-365a-5p known to directly targeting HDAC and NFkB a decrease of HDAC activity by NMRT was detected. The miR-25-5p target COX2 was changed in expression by NMRT whereas no influence on CDK4 knowing to be controlled by miR-24-1-5p was detected. NMRT treatment of chondrocytes under hypoxic conditions (0-5 % O<sub>2</sub>) changed the expression profile with respect to NOS, IGF2, PDGF and IGFBP and a change in the expression of Hif1/2 under the influence of IL1b was observed. The hypoxic conditions changed apoptotic behavior of the cells, NMRT showed no influence. <h3>Conclusion:</h3> A closer look into the mechanism of the NMRT at the cellular level revealed a modulatory effect on miRNA, their regulatory units and chondrocytes under hypoxic conditions. The results underline our former results indicating that NMRT counteracts IL-1b induced changes which mean that pain reduction by NMRT might be due to NMRT holding against inflammatory mechanisms under OA. <h3>References</h3> [1] Kullich W, Overbeck J, Spiegel HU; Journal of Back and Musculoskeletal Rehabilitation2013, 26:93-104. [2] Steinecker-Frohnwieser B, Kullich W, Mann A, Kress H, Weigl L; Exp. Clin. Rheum. 2018, 36, 2:0294-0301. <h3>Disclosure of Interests:</h3> Birgit Lohberger: None declared, Lukas Weigl: None declared, Nicole Stuendl: None declared, Anda Mann: None declared, Andreas Leithner: None declared, Werner Kullich Grant/research support from: minor research support for chemicals, Bibiane Steinecker-Frohnwieser Grant/research support from: research support