Developmental stage of oligodendrocytes determines their response to activated microglia in vitro

Miller, Brandon A.; Crum, Jeannine Marie; Tovar, C. Amy; Ferguson, Adam R.; Bresnahan, Jacqueline C.; Beattie, Michael S.

doi:10.1186/1742-2094-4-28

Cited by 56 publications

(56 citation statements)

References 72 publications

(79 reference statements)

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“…Other studies have acknowledged the increased incidence of cerebral palsy and OL damage in concurrence with maternal, fetal and placental infection [42,43] and several lines of research have illustrated mechanisms where inflammatory cytokines may cause brain injury. For instance, TNF-α has been demonstrated to have a direct effect on neurotoxicity by inhibiting the differentiation of OLs, stimulating OL apoptosis and causing demyelination [44,45,46]. Our observations of increased TNF-α concentration in the supernatant of mixed glial cultures support these findings and further support a role for TNF-α in the pathology of the OL in neuro-inflammatory insults.…”

Section: Discussionsupporting

confidence: 80%

Primary Mixed Glial Cultures from Fetal Ovine Forebrain Are a Valid Model of Inflammation-Mediated White Matter Injury

Weaver-Mikaere

Gibbons²,

Silva

et al. 2012

Dev Neurosci

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Astrocytes, microglial cells and oligodendrocytes (OLs) have been employed separately in vitro to assess cellular pathways following a variety of stimuli. Mixed glial cell cultures, however, have not been utilized to the same extent, despite the observed discrepancy in outcomes resulting from cell-to-cell contact of different glia in culture. Our objective was to standardize and morphologically characterize a primary culture of preterm ovine glial cells in order to attain a relevant in vitro model to assess the intracellular effects of infection and inflammation. This would provide a high-throughput model necessary for in-depth studies on the various pathophysiological mechanisms of white matter injury (WMI), which may occur in the preterm infant as a consequence of maternal infection or the fetal inflammatory response. Glial cells from the forebrains of 0.65-gestation ovine fetuses (comparable to 24- to 26-week human fetal brain development) were mechanically and enzymatically isolated and plated at a final density of 250,000 cells per well. When reaching confluence at 5 days after plating, the cultures contained astrocytes, microglial cells, as well as progenitor, precursor and immature OLs. Glial cell morphology and phenotypic immunoreactivity were characteristic of and consistent with previous observations of separately cultured cell types. To determine the effects of infection or inflammation in our in vitro model, we then treated mixed glial cultures with tumour necrosis factor-α (TNF-α; 50 or 100 ng/ml) or lipopolysaccharide (LPS; 1 µg/ml) for a period of 48 h. Cytokine levels were measured by ELISA and cell numbers for specific glial cell types were determined along with OL proliferation and apoptosis by Ki67 and caspase-3 immunocytochemistry, respectively. Our results showed that exposure to TNF-α or LPS resulted in a characteristic inflammatory response entailed by up-regulation of pro-inflammatory cytokines, a lack of astrogliosis and a marked reduction in OLs attributable to increased apoptosis. In LPS-treated cultures, there was a marked increase in the pro-inflammatory cytokine TNF-α at both 24 and 48 h. In conclusion, this is the first report of the immunocytochemical description and characterization of fetal ovine-derived mixed glial cell primary cultures. This in vitro model provides a novel and efficient system to explore the mechanisms of infection/inflammation-mediated WMI at the cellular level and for screening candidate therapeutic strategies.

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Section: Discussionsupporting

confidence: 80%

Primary Mixed Glial Cultures from Fetal Ovine Forebrain Are a Valid Model of Inflammation-Mediated White Matter Injury

Weaver-Mikaere

Gibbons²,

Silva

et al. 2012

Dev Neurosci

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“…These confounding responses may relate to the immunomodulatory effects of CS on microglia; the latter remove myelin debris (inhibitory to myelin genesis) and secrete stimulatory/inhibitory cytokines that can impact oligodendrocyte development. 24 However, CS treatment of astrocytes can also down-regulate oligodendroglial differentiation factors. 25 While neurons engage in cross-talk with oligodendroglial cells during myelination, one study has reported limited CS effects in striatal neurons, suggesting that at least some neurons are not direct targets of CS action.…”

mentioning

confidence: 99%

Identifying the Cellular Targets of Drug Action in the Central Nervous System Following Corticosteroid Therapy

Jenkins

Pickard

Khong

et al. 2013

ACS Chem. Neurosci.

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Corticosteroid (CS) therapy is used widely in the treatment of a range of pathologies, but can delay production of myelin, the insulating sheath around central nervous system nerve fibers. The cellular targets of CS action are not fully understood, that is, "direct" action on cells involved in myelin genesis [oligodendrocytes and their progenitors the oligodendrocyte precursor cells (OPCs)] versus "indirect" action on other neural cells. We evaluated the effects of the widely used CS dexamethasone (DEX) on purified OPCs and oligodendrocytes, employing complementary histological and transcriptional analyses. Histological assessments showed no DEX effects on OPC proliferation or oligodendrocyte genesis/maturation (key processes underpinning myelin genesis). Immunostaining and RT-PCR analyses show that both cell types express glucocorticoid receptor (GR; the target for DEX action), ruling out receptor expression as a causal factor in the lack of DEX-responsiveness. GRs function as ligand-activated transcription factors, so we simultaneously analyzed DEX-induced transcriptional responses using microarray analyses; these substantiated the histological findings, with limited gene expression changes in DEX-treated OPCs and oligodendrocytes. With identical treatment, microglial cells showed profound and global changes post-DEX addition; an unexpected finding was the identification of the transcription factor Olig1, a master regulator of myelination, as a DEX responsive gene in microglia. Our data indicate that CS-induced myelination delays are unlikely to be due to direct drug action on OPCs or oligodendrocytes, and may occur secondary to alterations in other neural cells, such as the immune component. To the best of our knowledge, this is the first comparative molecular and cellular analysis of CS effects in glial cells, to investigate the targets of this major class of anti-inflammatory drugs as a basis for myelination deficits.

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“…However, at the acute phase of injury, macrophages infiltrating from the blood and constitutive microglia are activated and may be toxic to the OPCs. Studies have shown that activated microglia are harmful to OPCs and reduce their survival [25,26].…”

Section: Discussionmentioning

confidence: 99%

Myelination of Motor Neurons Derived from Mouse Embryonic Stem Cells by Oligodendrocytes Derived from Mouse Embryonic Stem Cells in a Microfluidic Compartmentalized Platform

Xiang¹,

Fisgin²,

Thakor³

2015

J Stem Cell Res Ther

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Developmental stage of oligodendrocytes determines their response to activated microglia in vitro

Cited by 56 publications

References 72 publications

Primary Mixed Glial Cultures from Fetal Ovine Forebrain Are a Valid Model of Inflammation-Mediated White Matter Injury

Primary Mixed Glial Cultures from Fetal Ovine Forebrain Are a Valid Model of Inflammation-Mediated White Matter Injury

Identifying the Cellular Targets of Drug Action in the Central Nervous System Following Corticosteroid Therapy

Myelination of Motor Neurons Derived from Mouse Embryonic Stem Cells by Oligodendrocytes Derived from Mouse Embryonic Stem Cells in a Microfluidic Compartmentalized Platform

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