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The plasticity of macrophages in the immune response is a dynamic situation dependent on external stimuli. The activation of macrophages both has beneficial and detrimental effects on mature oligodendrocytes (OLs) and myelin. The activation towards inflammatory macrophages has a critical role in the immune-mediated oligodendrocytes death in multiple sclerosis (MS) lesions. We established an in vitro co-culture method to study the function of macrophages in the survival and maturation of OLs. We revealed that M1 macrophages decreased the number of mature OLs and phagocytosed the myelin. Interestingly, non-activated as well as M2 macrophages contributed to an increase in the number of mature OLs in our in vitro co-culture platform. We added an antibody against an OL surface antigen in our in vitro co-cultures. The antibody presents the OLs to the macrophages enabling the investigation of direct interactions between macrophages and OLs. Our co-culture system is a feasible method for the investigation of the direct cell-to-cell interactions between OLs and macrophages. We utilized it to show that M2 and non-activated macrophages may be employed to enhance remyelination. [Display omitted] • A new in vitro co-culture method to study demyelination and remyelination. • Peritoneal M1 macrophages increased the death of mature oligodendrocytes. • Peritoneal non-activated macrophages increased the number of mature oligodendrocytes. • Non-activated macrophages can be targeted for therapeutic purposes. [ABSTRACT FROM AUTHOR]

Objective: Myelin is essential for a healthy nervous system. Myelin formed by oligodendrocytes, accelerates impulse propagation and supports neuronal survival. Demyelination leads to neurodegeneration. In multiple sclerosis (MS) immune attack results in demyelination. Our goal is to dissect interactions among oligodendrocytes, neurons, and immune cells to improve our understanding of myelination and the demyelinating diseases. We aim to discover new targets for remyelination therapies. Methods: We are building tools for analyzing protein-protein and cell-to-cell interactions. To identify genes involved in myelination and MS, we developed a bioinformatics-based strategy, interactome analysis, which combines proteome and gene expression methodologies. Identified genes are evaluated in peripheral blood of MS patients and in mouse models. To accelerate drug discovery, 23 machine learning-based methodologies were assessed for myelin identification in fluorescent microscopy images. Results: Interactome analysis identified hundreds of proteinprotein interactions between pairs of oligodendrocytes, neurons, macrophages, microglia, and T cells. Most significant interactions are further analyzed in vivo and in vitro. Our customizedconvolutional neural network and Boosted Tree methods segmented myelin at over 98% accuracy. Identified myelin can be quantified and visualized in 3D. Conclusion: The interactome analysis yielded novel genes that are likely to be linked to MS. Machine learning-based methodologies are very effective in accelerating myelin quantification and thus, drug screens against demyelinating diseases such as MS. Overall, our innovative analysis strategies employing computer assistance produced novel avenues of exploration for myelination and demyelinating diseases. This study was supported TUBITAK (218S495,316S026), Istanbul Medipol University (BAP2018/06), and Turkish Academy of Sciences (GEBIP). [ABSTRACT FROM AUTHOR]

Objective: Macrophages have a dual effect on multiple sclerosis (MS) they promote remyelination via secreted factors and they phagocytose myelin causing demyelination. Thus, signaling pathways regulating macrophage physiology are investigated as therapeutic targets. Among those pathways, dopamine and adenosine signaling pathways, drew attention due to positive results in animal models. Additionally, the two pathways were shown to act synergistically in in vitro experiments. Therefore, synergistic modulation of dopamine and adenosine pathways in macrophages may be a key target for MS therapy. Goal of this study is to investigate the effect of modulation of dopamine and adenosine pathways on myelin damage and remyelination using macrophage oligodendrocyte co-cultures. Methods: First, co-cultures were established with inactivated and lipopolysaccharide (LPS)-activated macrophages isolated from adult mice peritoneum and oligodendrocytes differentiated from the cortex of newborn mice. 48-hour old co-cultures were treated with single, double and triple combinations of dopamine signaling pathway agonist (Quinpirole), adenosine signaling pathway agonist (Istradefylline) and antagonist (CGS21680). Then, co-cultures were fixed and analyzed using immunocytochemistry. Macrophages were labeled with CD11b, oligodendrocytes with SOX10 and mature oligodendrocytes with Myelin Basic Protein (MBP) and quantified by cell counting. Results: In co-cultures with inactivated and LPS-activated macrophages, an increase in the number of mature oligodendrocytes was observed while the total number of oligodendrocytes did not change. However, a triple combination of agonists and antagonist treatment reduced number of mature oligodendrocytes in the LPS-activated macrophage-oligodendrocyte co-cultures. Conclusion: Inactive and LPS-activated macrophages increased the number of mature oligodendrocytes under co-culture conditions. Therefore, macrophages have a positive effect on oligodendrocytes when not activated by MS cues or to a similar extend and LPS treatment alone is not enough to simulate MS like conditions. Observed positive effect can be inhibited by modulating dopamine and adenosine signaling pathways. We thank TUBITAK for their support. [ABSTRACT FROM AUTHOR]