The Effects of anti-inflammatory cytokines, neurotrophic factors and interferon-beta on in vitro apoptotic death of murine oligodendrocytes

12 2. İNGİLİZCE ÖZET The effects of anti-inflammatory cytokines, neurotrophic factors and interferon- beta on in vitro apoptotic death of murine oligodendrocytes Dr. Kemal Kürşad GENÇ Background, purpose, aim of the study : Oligodendrocytes (OL) are glial cells that are responsible for myelin production. OL injury and apoptotic cell death occur in acute and chronic neurodegenerative disorders. Therefore, determining the agents that may prevent OL death in various injury models in vitro might contribute to establish effective treatment strategies for these disorders. For this purpose, in the present study it has been investigated that whether interferon-beta (IFNP), transforming growth factor-beta (TGFp), hepatocyte growth iâctor (HGF), nerve growth actor (NGF) and erythropoietin (EPO) have protective action against OL death that is induced by interferon-gamma (IFNy), tumor necrosis actor- alpha (TNFa), Hpopoh/saccharide (LPS) and serum deprivation (SD). Material and methods : In this study, OL injury has been induced by 100 U/ml IFNy + 100 ng/ml TNFa, 100 U/ml IFNy + 1 jig/ml LPS and SD in neonatal mice OL and N20.1 immature OL cell line cultures. The OL injury and the possible protective actions of candidate agents have been evaluated by 3-(4,5-dimethylthiazol-2-yI)-2,5-diphenyltetrazolium bromide (MTT) cell viability assay and Lactic dehydrogenase (LDH) cytotoxicity assay. Apostain immunofluorescein (IF) staining has been used for the evaluation of apoptotic cell death. The protein and mRNA expression of EPO receptor (EPOR) has been searched by IF staining, Western blotting (WB)-Immunoprecipitation (IP) and Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) techniques respectively. Results : The results of the present study shows that IFNp\ TGFp\ HGF and NGF have no protective action in the injury models that have been used. In contrast to this, EPO shows protective action on OL and prevents apoptotic cell death. It has been demonstrated that OL expresses baseline EPOR as shown by IF staining and N20.1 cells express both EPOR protein and EPOR mRNA as shown by WP-IP and RT-PCR techniques respectively. It has been shown that EPOR mRNA expression is induced by IFNy and LPS treatment of cultures.13 Discussion : These results show that EPO which is one of the agents that have been tested in this study prevents cell injury and apoptotic cell death in various in vitro cell injury models and that baseline and inflammatory stimuli-induced EPOR protein and mRNA expression exist in OL. This is the first in vitro study that presents the oligodendroglioprotective action of EPO which of the neuroprotective action has been demonstrated by recent studies in various disease models in vivo and injury models in vitro. These results suggest that EPO that is currently used for the treatment of chronic anemia might contribute to the treatment of acute and chronic neurodegenerative disorders such as stroke, trauma, Alzheimer's disease and multiple sclerosis which in OL death and white matter injury occur. Keywords : Oligodendrocyte; apoptosis; eritropoietin; neurotrophic factors; interferon-beta; anti-inflammatory cytokines; mouse