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

Miller BA, Crum JM, Tovar CA, Ferguson AR, Bresnahan JC, Beattie MS - J Neuroinflammation (2007)

Bottom Line: Lipopolysaccharide was used to activate microglia and microglial activation was confirmed by TNFalpha ELISA.Activated microglia reduced OPC survival, but increased survival and reduced apoptosis of mature oligodendrocytes.Activated microglia may have divergent effects on OPCs and mature oligodendrocytes, reducing OPC survival and increasing mature oligodendrocyte survival.

View Article: PubMed Central - HTML - PubMed

Affiliation: Brain and Spinal Injury Center, Department of Neurological Surgery, University of California San Francisco, 1001 Potrero Ave, Building 1, Room 101, San Francisco, CA 94143, USA. Brandon.Miller@osumc.edu

ABSTRACT

Background: Oligodendrocyte progenitor cells (OPCs) and mature oligodendrocytes are both lost in central nervous system injury and disease. Activated microglia may play a role in OPC and oligodendrocyte loss or replacement, but it is not clear how the responses of OPCs and oligodendrocytes to activated microglia differ.

Methods: OPCs and microglia were isolated from rat cortex. OPCs were induced to differentiate into oligodendrocytes with thyroid hormone in defined medium. For selected experiments, microglia were added to OPC or oligodendrocyte cultures. Lipopolysaccharide was used to activate microglia and microglial activation was confirmed by TNFalpha ELISA. Cell survival was assessed with immunocytochemistry and cell counts. OPC proliferation and oligodendrocyte apoptosis were also assessed.

Results: OPCs and oligodendrocytes displayed phenotypes representative of immature and mature oligodendrocytes, respectively. Activated microglia reduced OPC survival, but increased survival and reduced apoptosis of mature oligodendrocytes. Activated microglia also underwent cell death themselves.

Conclusion: Activated microglia may have divergent effects on OPCs and mature oligodendrocytes, reducing OPC survival and increasing mature oligodendrocyte survival. This may be of importance because activated microglia are present in several disease states where both OPCs and mature oligodendrocytes are also reacting to injury. Activated microglia may simultaneously have deleterious and helpful effects on different cells after central nervous system injury.

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LPS-activated microglia induce OPC cell death. OPCs were cultured in combination with microglia (A). Dead OPCs were not able to be quantified due to scattered debris (B), so OPC survival was measured by counting the number of live OPCs. LPS or microglia alone had no effect on OPC survival but microglia activated with LPS significantly reduced OPC survival (C, * = p < 0.05 from control, Tukey's, error bars = SEM).
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Figure 3: LPS-activated microglia induce OPC cell death. OPCs were cultured in combination with microglia (A). Dead OPCs were not able to be quantified due to scattered debris (B), so OPC survival was measured by counting the number of live OPCs. LPS or microglia alone had no effect on OPC survival but microglia activated with LPS significantly reduced OPC survival (C, * = p < 0.05 from control, Tukey's, error bars = SEM).

Mentions: For these experiments, pure OPC cultures, without and with microglia added, were utilized (Fig. 3A). There was no effect of 10 ng/ml LPS on the number of live OPCs when OPCs were cultured alone; additionally, there was no effect of microglia alone on OPC number. In OPC-microglia combined cultures, there was a significant reduction in OPC number when 10 ng/ml LPS was added for 24 hours (Fig. 3B,C). The number of OPCs in the presence of microglia plus LPS was reduced to 34 ± 5% of control values (p = 0.002, ANOVA, Tukey's post-hoc), indicating that LPS-activated microglia decreased OPC survival. Factorial ANOVA revealed a significant (p = 0.036) interaction between microglia and LPS, and a significant main effect of microglia (p = 0.001).


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

Miller BA, Crum JM, Tovar CA, Ferguson AR, Bresnahan JC, Beattie MS - J Neuroinflammation (2007)

LPS-activated microglia induce OPC cell death. OPCs were cultured in combination with microglia (A). Dead OPCs were not able to be quantified due to scattered debris (B), so OPC survival was measured by counting the number of live OPCs. LPS or microglia alone had no effect on OPC survival but microglia activated with LPS significantly reduced OPC survival (C, * = p < 0.05 from control, Tukey's, error bars = SEM).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2214724&req=5

Figure 3: LPS-activated microglia induce OPC cell death. OPCs were cultured in combination with microglia (A). Dead OPCs were not able to be quantified due to scattered debris (B), so OPC survival was measured by counting the number of live OPCs. LPS or microglia alone had no effect on OPC survival but microglia activated with LPS significantly reduced OPC survival (C, * = p < 0.05 from control, Tukey's, error bars = SEM).
Mentions: For these experiments, pure OPC cultures, without and with microglia added, were utilized (Fig. 3A). There was no effect of 10 ng/ml LPS on the number of live OPCs when OPCs were cultured alone; additionally, there was no effect of microglia alone on OPC number. In OPC-microglia combined cultures, there was a significant reduction in OPC number when 10 ng/ml LPS was added for 24 hours (Fig. 3B,C). The number of OPCs in the presence of microglia plus LPS was reduced to 34 ± 5% of control values (p = 0.002, ANOVA, Tukey's post-hoc), indicating that LPS-activated microglia decreased OPC survival. Factorial ANOVA revealed a significant (p = 0.036) interaction between microglia and LPS, and a significant main effect of microglia (p = 0.001).

Bottom Line: Lipopolysaccharide was used to activate microglia and microglial activation was confirmed by TNFalpha ELISA.Activated microglia reduced OPC survival, but increased survival and reduced apoptosis of mature oligodendrocytes.Activated microglia may have divergent effects on OPCs and mature oligodendrocytes, reducing OPC survival and increasing mature oligodendrocyte survival.

View Article: PubMed Central - HTML - PubMed

Affiliation: Brain and Spinal Injury Center, Department of Neurological Surgery, University of California San Francisco, 1001 Potrero Ave, Building 1, Room 101, San Francisco, CA 94143, USA. Brandon.Miller@osumc.edu

ABSTRACT

Background: Oligodendrocyte progenitor cells (OPCs) and mature oligodendrocytes are both lost in central nervous system injury and disease. Activated microglia may play a role in OPC and oligodendrocyte loss or replacement, but it is not clear how the responses of OPCs and oligodendrocytes to activated microglia differ.

Methods: OPCs and microglia were isolated from rat cortex. OPCs were induced to differentiate into oligodendrocytes with thyroid hormone in defined medium. For selected experiments, microglia were added to OPC or oligodendrocyte cultures. Lipopolysaccharide was used to activate microglia and microglial activation was confirmed by TNFalpha ELISA. Cell survival was assessed with immunocytochemistry and cell counts. OPC proliferation and oligodendrocyte apoptosis were also assessed.

Results: OPCs and oligodendrocytes displayed phenotypes representative of immature and mature oligodendrocytes, respectively. Activated microglia reduced OPC survival, but increased survival and reduced apoptosis of mature oligodendrocytes. Activated microglia also underwent cell death themselves.

Conclusion: Activated microglia may have divergent effects on OPCs and mature oligodendrocytes, reducing OPC survival and increasing mature oligodendrocyte survival. This may be of importance because activated microglia are present in several disease states where both OPCs and mature oligodendrocytes are also reacting to injury. Activated microglia may simultaneously have deleterious and helpful effects on different cells after central nervous system injury.

Show MeSH
Related in: MedlinePlus