OP0136 THE INFLUENCE OF LONG-TERM EXERCISE AND IN VITRO EXERCISE-MIMICKING STIMULATION ON THE PRODUCTION OF MYOKINES AND CYTOKINES IN MYOTUBES OF PATIENTS WITH CHRONIC IDIOPATHIC INFLAMMATORY MYOPATHIES
Authors: M. Vokurková, L. Vernerová, M. Špiritović, H. Štorkánová, S. Oreska, M. Klein, J. Ukropec, B. Ukropcová, M. Tomčík, J. Vencovský
Journal: Annals of the Rheumatic Diseases (2020)

Background: It has been demonstrated several times that endurance exercise has beneficial effects on the condition of patients with idiopathic inflammatory myopathies (IIM). Muscle contraction during exercise is a major stimulus for the release of myokines that are supposed to take part in the beneficial adaption to exercise. Objectives: The aim of this study was to find out how a six-month physiotherapy and in vitro exercise-mimicking treatment affect myokine and cytokine production in myotubes of IIM patients. Methods: Seven patients with chronic IIM took part in a six-month physiotherapy (stretching and strengthening), which significantly improved their muscle strength and endurance. IIM patients (n=7) before and after the six months exercise and their respective healthy counterparts (HC, n=9) underwent a musculus vastus lateralis biopsy. Isolated skeletal muscle cells were grown, differentiated into myotubes, which were treated with a pharmacological cocktail: palmitate, forskolin and ionomycin (PFI) to mimic exercise-stimulated contractions in vitro. Myokine and cytokine concentrations produced by myotubes to the culture medium were analyzed with ELISA and the multiplex immunoassay, respectively. RT-PCR was used for the evaluation of myokine gene expression in the cultured myotubes. Results: Compared to myotubes of healthy controls, myotubes of IIM patient released more myostatin and activin A into the medium. The myostatin gene was expressed significantly more in muscle cells of patients than in healthy controls’ cells (p&lt;0.05). After a six-month rehabilitation program, activin A secretion was four-fold reduced in myotubes of patients with IIM, while myostatin release and gene expression remained unchanged. In myotubes of IIM patients, less follistatin and more follistatin like 3 were detected in the culture medium compared to HC myotubes. Myotubes derived from IIM patients after six months of rehabilitation secreted twice as much follistatin and half the amount of follistatin like 3 into the medium than myotubes derived from IIM patients prior to rehabilitation (p&lt;0.05). There was no difference in secretion of interleukin (IL) 6, IL-17, tumor necrosis factor (TNF) and vascular endothelial growth factor (VEGF) between myotubes of IIM patients and myotubes of HC. However, six-month exercise significantly (p&lt;0.05) reduced release of IL-6, TNF and VEGF in myotubes of IIM patients. Contrary to our expectation, stimulation of PFI had no effect on the release of myostatin, activin A, follistatin and follistatin like 3, or the expression of their genes. PFI treatment significantly (p&lt;0.05) increased IL-6 secretion in myotubes from HC and IIM patients prior to six months of rehabilitation. On the other hand, it was observed that myotubes of HC and IIM patients exposed to the PFI cocktail secreted significantly less inflammatory cytokines IL-17, TNF and VEGF into the medium compared to unstimulated myotubes (p&lt;0.05). Conclusion: In conclusion, long-term exercise influenced the production of myokines and decreased release of inflammatory cytokines in myotubes of IIM patients. In vitro exercise-mimicking treatment increased the secretion of IL-6 and decreased the release of inflammatory cytokines as IL-17, TNF-α and VEGF in myotubes of patients with IIM and healthy individuals. Acknowledgments: This work was supported by the Ministry of Health of the Czech Republic grants nr. 16-33746A and donation 140.0000008. Disclosure of Interests: None declared