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Isolation of Cortical Microglia with Preserved Immunophenotype and Functionality From Murine Neonates
Published on: January 30, 2014
Pretreatment with interferon-gamma protects microglia from oxidative stress via up-regulation of Mn-SOD
Xia Chen1, In Young Choi, Tong-Shin Chang
1Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang, China.
Abstract:
Microglial cells, resident macrophage-like immune cells in the brain, are exposed to intense oxidative stress under various pathophysiological conditions. For self-defense against oxidative injuries, microglial cells must be equipped with antioxidative mechanisms. In this study, we investigated the regulation of antioxidant enzyme systems in microglial cells by interferon-gamma (IFN-gamma) and found that pretreatment with IFN-gamma for 20 h protected microglial cells from the toxicity of various reactive species such as hydrogen peroxide (H(2)O(2)), superoxide anion, 4-hydroxy-2(E)-nonenal, and peroxynitrite. The cytoprotective effect of IFN-gamma pretreatment was abolished by the protein synthesis inhibitor cycloheximide. In addition, treatment of microglial cells with both IFN-gamma and H(2)O(2) together did not protect them from the H(2)O(2)-evoked toxicity. These results imply that protein synthesis is required for the protection by IFN-gamma. Among various antioxidant enzymes such as manganese or copper/zinc superoxide dismutase (Mn-SOD or Cu/Zn-SOD), catalase, and glutathione peroxidase (GPx), only Mn-SOD was up-regulated in IFN-gamma-pretreated microglial cells. Transfection with siRNA of Mn-SOD abolished both up-regulation of Mn-SOD expression and protection from H(2)O(2) toxicity by IFN-gamma pretreatment. Furthermore, whereas the activities of Mn-SOD and catalase were up-regulated by IFN-gamma pretreatment, those of Cu/Zn-SOD and GPx were not. These results indicate that IFN-gamma pretreatment protects microglial cells from oxidative stress via selective up-regulation of the level of Mn-SOD and activity of Mn-SOD and catalase.
Insights
Interferon-gamma (IFN-gamma) pretreatment protects brain microglial cells from oxidative stress by increasing manganese superoxide dismutase (Mn-SOD). This protective effect requires protein synthesis and involves up-regulation of Mn-SOD levels and activity.
Area of Science:
- Neuroimmunology
- Cellular Biology
- Oxidative Stress Research
Background:
- Microglial cells, the brain's resident immune cells, are susceptible to oxidative stress in various diseases.
- Effective antioxidative mechanisms are crucial for microglial cell survival and function.
Purpose of the Study:
- To investigate how interferon-gamma (IFN-gamma) regulates antioxidant enzyme systems in microglial cells.
- To determine the role of protein synthesis in IFN-gamma-mediated protection against oxidative stress.
Main Methods:
- Microglial cells were pretreated with IFN-gamma and subsequently exposed to various reactive oxygen species.
- Protein synthesis inhibition (using cycloheximide) and gene silencing (using siRNA for Mn-SOD) were employed.
- Levels and activities of antioxidant enzymes including Mn-SOD, Cu/Zn-SOD, catalase, and GPx were measured.
Main Results:
- IFN-gamma pretreatment protected microglial cells from toxicity induced by hydrogen peroxide, superoxide anion, 4-hydroxy-2(E)-nonenal, and peroxynitrite.
- The protective effect was dependent on protein synthesis and was abolished by cycloheximide.
- Only manganese superoxide dismutase (Mn-SOD) expression was significantly up-regulated by IFN-gamma.
- Silencing Mn-SOD abolished IFN-gamma's protective effects against hydrogen peroxide toxicity.
- IFN-gamma increased the activities of Mn-SOD and catalase, but not Cu/Zn-SOD or GPx.
Conclusions:
- IFN-gamma pretreatment confers cytoprotection to microglial cells against oxidative stress.
- This protection is mediated by the selective up-regulation of manganese superoxide dismutase (Mn-SOD) at both the expression and activity levels.
- Protein synthesis is essential for IFN-gamma-induced antioxidative defense in microglial cells.
