Demyelination induced by oxidative stress is regulated by sphingosine 1‐phosphate receptors

• Published in: Glia 2017-07, Vol.65 (7), p.1119-1136
• Main Authors: O'Sullivan, Sinead A., Velasco‐Estevez, Maria, Dev, Kumlesh K.
• Format: Article
• Language: English
• Subjects: Animal models; Animals; Animals, Newborn; Astrocytes - drug effects; Astrocytes - physiology; Attenuation; Brain - cytology; Catalase; Cell culture; Cell death; Cells, Cultured; cerebellar slices; Cerebellum; Cerebellum - drug effects; Cytokines; Data processing; Demyelinating Diseases - drug therapy; Demyelinating Diseases - etiology; Demyelinating Diseases - metabolism; Demyelination; Deoxyribonucleic acid; DNA; DNA damage; DNA repair; DNA-Binding Proteins - metabolism; Female; Fetus; Fingolimod Hydrochloride - therapeutic use; Gene Expression Regulation - drug effects; Glucose oxidase; Humans; Hydrogen peroxide; Hydrogen Peroxide - toxicity; Immunoreactivity; Immunosuppressive Agents - therapeutic use; In vitro methods and tests; Inflammation; Interleukin 6; low continuous H2O2, pFTY720; Male; Mice; Mice, Inbred C57BL; Mitochondrial DNA; Multiple sclerosis; Myelin-Oligodendrocyte Glycoprotein - metabolism; Myelination; Neurofilament Proteins - metabolism; Oxidative stress; Oxidative Stress - drug effects; Oxidative Stress - physiology; Phosphates; Reactive oxygen species; Receptors; Receptors, Lysosphingolipid - genetics; Receptors, Lysosphingolipid - metabolism; Repressor Proteins - metabolism; Rodents; Sphingosine 1-phosphate; Sphingosine 1-phosphate receptors; Substantia alba; Vimentin; Zebrafish Proteins - metabolism
• ISSN: 0894-1491; 1098-1136
• DOI: 10.1002/glia.23148

Oxidative stress is a pathological condition defined as an imbalance between production and removal of reactive oxygen species. This process causes structural cell damage, disrupts DNA repair and induces mitochondrial dysfunction. Many in vitro studies have used direct bolus application of H2O2 to investigate the role of oxidative stress in cell culture. In this study, using mouse organotypic cerebellar slice cultures, the effects of H2O2‐induced oxidative stress on myelination state were examined, using bolus concentrations of H2O2 (0.1–1 mM) and low‐continuous H2O2 (∼20 μM) generated from glucose oxidase and catalase (GOX‐CAT). Using these models, the potential therapeutic effects of pFTY720, an oral therapy used in multiple sclerosis, was also examined. We found bolus treatment of H2O2 (0.5 mM) and, for the first time, low‐continuous H2O2 (GOX‐CAT) to induce demyelination in organotypic slices. Both bolus H2O2 and GOX‐CAT treatments significantly decreased vimentin expression in these slice cultures as well as increased cell death in isolated astrocyte cultures. Importantly, pre‐treatment with pFTY720 significantly attenuated both bolus H2O2 and GOX‐CAT‐induced demyelination and the GOX‐CAT‐induced decrease in vimentin in cerebellar slices, without altering levels of the proinflammatory cytokines such as IL‐6 and CX3CL1. We also observed increased SMI‐32 immunoreactivity in the white matter tract induced by GOX‐CAT indicating axonal damage, which was remarkably attenuated by pFTY720. Taken together, this data establishes a novel GOX‐CAT model of demyelination and demonstrates that pFTY720 can act independently of inflammatory cytokines to attenuate decreases in vimentin, as well as axonal damage and demyelination induced by oxidative stress. Main Points Bolus H2O2 and low continuous H2O2 induces demyelination and axonal damage in organotypic slices, which is attenuated by pFTY720. The protective effects of pFTY720 are independent of changes in select pro‐inflammatory cytokines.