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NOD2 is involved in the inflammatory response after cerebral ischemia-reperfusion injury and triggers NADPH oxidase 2-derived reactive oxygen species.

Liu H, Wei X, Kong L, Liu X, Cheng L, Yan S, Zhang X, Chen L - Int. J. Biol. Sci. (2015)

Bottom Line: Our results showed that NOD2 expression was significantly increased in microglia and astrocytes in response to the I/R insult.Genetic ablation of the NOD2 gene significantly improved stroke outcomes and reduced inflammation, as evidenced by a lower expression of the pro-inflammatory cytokines IL-1β, IL-6 and TNFα in conjunction with attenuated activation of nuclear factor κB (NF-κB), p38 mitogen activated protein kinases (MAPK) and JNK.Pharmacological targeting of NOD2-mediated inflammatory response at multiple levels may help design a new approach to develop therapeutic strategies for prevention of deterioration of cerebral function and for the treatment of stroke.

View Article: PubMed Central - PubMed

Affiliation: 1. Department of Pharmacology, School of Medicine, Shandong University, Wenhua West Road 44, Jinan, Shandong 250012, P.R. China.

ABSTRACT

Background: Increasing evidences suggest that innate immunity is involved in cerebral ischemia-reperfusion (I/R) injury, but the liable innate immune receptors have not been completely elucidated. Here, we explored the role of the nucleotide-binding oligomerization domain (NOD)2, a member of the cytosolic NOD-like receptor family, in acute focal cerebral I/R injury.

Methods: An in vivo middle cerebral artery occlusion (MCAO) model that in wild type (WT) and NOD2 deficient (NOD2(-/-)) mice and in vitro model of oxygen glucose deprivation and reoxygenation (OGD/R) in cultured primary microglia and astrocytes were used to investigate the expression of NOD2 and explore the roles of NOD2 in ischemic stroke.

Results: Our results showed that NOD2 expression was significantly increased in microglia and astrocytes in response to the I/R insult. Pretreatment with muramyl dipeptide, an extrinsic ligand of NOD2, significantly increased the infarct volume and neurological dysfunction in mice subjected to MCAO. Genetic ablation of the NOD2 gene significantly improved stroke outcomes and reduced inflammation, as evidenced by a lower expression of the pro-inflammatory cytokines IL-1β, IL-6 and TNFα in conjunction with attenuated activation of nuclear factor κB (NF-κB), p38 mitogen activated protein kinases (MAPK) and JNK. Moreover, NOD2 deficiency prevented the upregulation of the NADPH oxidase (NOX) 2 and ROS generation induced by I/R. Mechanistically, NOD2-induced production of IL-6 in primary cultured microglia was mediated through activation of NOX2.

Conclusions: This study showed the contribution of NOD2 to inflammatory response and provided direct evidence that NOX2-mediated oxidative stress as an important target molecule linked NOD2 to inflammatory damage in ischemic stroke. Pharmacological targeting of NOD2-mediated inflammatory response at multiple levels may help design a new approach to develop therapeutic strategies for prevention of deterioration of cerebral function and for the treatment of stroke.

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The expressions of NOD2 in astrocytes and microglia cells were upregulated after 1 h oxygen-glucose deprivation (OGD) and 24 h reperfusion in vitro. (A) Immunofluorescent staining indicating that NOD2 is expressed and enhanced by OGD both in microglial cells and in astrocytes, scale bars: 50 μm. (B) Western blot analysis of NOD2 expression in astrocytes and microglial cells subjected to 1 h OGD and 24 h reperfusion in vitro. Results are representative of four independent experiments. *P<0.05, OGD/R group compare with control group.
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Figure 2: The expressions of NOD2 in astrocytes and microglia cells were upregulated after 1 h oxygen-glucose deprivation (OGD) and 24 h reperfusion in vitro. (A) Immunofluorescent staining indicating that NOD2 is expressed and enhanced by OGD both in microglial cells and in astrocytes, scale bars: 50 μm. (B) Western blot analysis of NOD2 expression in astrocytes and microglial cells subjected to 1 h OGD and 24 h reperfusion in vitro. Results are representative of four independent experiments. *P<0.05, OGD/R group compare with control group.

Mentions: Firstly, by real-time RT-PCR (Fig. 1A) and western blotting (Fig. 1B) analyses, we found that NOD2 expression was markedly enhanced in the ischemic penumbra with a peak expression at 24 h after reperfusion. We further found that NOD2 was significant upregulated in microglia/macrophages and astrocytes by double immunofluorescent analysis (Fig. 1C), which was further confirmed by double immunofluorescence staining (Fig. 2A) and western blot analysis (Fig.2B) in primary cultured microglia and astrocytes subjected to 1 h OGD and 24 h reoxygenation in vitro.


NOD2 is involved in the inflammatory response after cerebral ischemia-reperfusion injury and triggers NADPH oxidase 2-derived reactive oxygen species.

Liu H, Wei X, Kong L, Liu X, Cheng L, Yan S, Zhang X, Chen L - Int. J. Biol. Sci. (2015)

The expressions of NOD2 in astrocytes and microglia cells were upregulated after 1 h oxygen-glucose deprivation (OGD) and 24 h reperfusion in vitro. (A) Immunofluorescent staining indicating that NOD2 is expressed and enhanced by OGD both in microglial cells and in astrocytes, scale bars: 50 μm. (B) Western blot analysis of NOD2 expression in astrocytes and microglial cells subjected to 1 h OGD and 24 h reperfusion in vitro. Results are representative of four independent experiments. *P<0.05, OGD/R group compare with control group.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4400384&req=5

Figure 2: The expressions of NOD2 in astrocytes and microglia cells were upregulated after 1 h oxygen-glucose deprivation (OGD) and 24 h reperfusion in vitro. (A) Immunofluorescent staining indicating that NOD2 is expressed and enhanced by OGD both in microglial cells and in astrocytes, scale bars: 50 μm. (B) Western blot analysis of NOD2 expression in astrocytes and microglial cells subjected to 1 h OGD and 24 h reperfusion in vitro. Results are representative of four independent experiments. *P<0.05, OGD/R group compare with control group.
Mentions: Firstly, by real-time RT-PCR (Fig. 1A) and western blotting (Fig. 1B) analyses, we found that NOD2 expression was markedly enhanced in the ischemic penumbra with a peak expression at 24 h after reperfusion. We further found that NOD2 was significant upregulated in microglia/macrophages and astrocytes by double immunofluorescent analysis (Fig. 1C), which was further confirmed by double immunofluorescence staining (Fig. 2A) and western blot analysis (Fig.2B) in primary cultured microglia and astrocytes subjected to 1 h OGD and 24 h reoxygenation in vitro.

Bottom Line: Our results showed that NOD2 expression was significantly increased in microglia and astrocytes in response to the I/R insult.Genetic ablation of the NOD2 gene significantly improved stroke outcomes and reduced inflammation, as evidenced by a lower expression of the pro-inflammatory cytokines IL-1β, IL-6 and TNFα in conjunction with attenuated activation of nuclear factor κB (NF-κB), p38 mitogen activated protein kinases (MAPK) and JNK.Pharmacological targeting of NOD2-mediated inflammatory response at multiple levels may help design a new approach to develop therapeutic strategies for prevention of deterioration of cerebral function and for the treatment of stroke.

View Article: PubMed Central - PubMed

Affiliation: 1. Department of Pharmacology, School of Medicine, Shandong University, Wenhua West Road 44, Jinan, Shandong 250012, P.R. China.

ABSTRACT

Background: Increasing evidences suggest that innate immunity is involved in cerebral ischemia-reperfusion (I/R) injury, but the liable innate immune receptors have not been completely elucidated. Here, we explored the role of the nucleotide-binding oligomerization domain (NOD)2, a member of the cytosolic NOD-like receptor family, in acute focal cerebral I/R injury.

Methods: An in vivo middle cerebral artery occlusion (MCAO) model that in wild type (WT) and NOD2 deficient (NOD2(-/-)) mice and in vitro model of oxygen glucose deprivation and reoxygenation (OGD/R) in cultured primary microglia and astrocytes were used to investigate the expression of NOD2 and explore the roles of NOD2 in ischemic stroke.

Results: Our results showed that NOD2 expression was significantly increased in microglia and astrocytes in response to the I/R insult. Pretreatment with muramyl dipeptide, an extrinsic ligand of NOD2, significantly increased the infarct volume and neurological dysfunction in mice subjected to MCAO. Genetic ablation of the NOD2 gene significantly improved stroke outcomes and reduced inflammation, as evidenced by a lower expression of the pro-inflammatory cytokines IL-1β, IL-6 and TNFα in conjunction with attenuated activation of nuclear factor κB (NF-κB), p38 mitogen activated protein kinases (MAPK) and JNK. Moreover, NOD2 deficiency prevented the upregulation of the NADPH oxidase (NOX) 2 and ROS generation induced by I/R. Mechanistically, NOD2-induced production of IL-6 in primary cultured microglia was mediated through activation of NOX2.

Conclusions: This study showed the contribution of NOD2 to inflammatory response and provided direct evidence that NOX2-mediated oxidative stress as an important target molecule linked NOD2 to inflammatory damage in ischemic stroke. Pharmacological targeting of NOD2-mediated inflammatory response at multiple levels may help design a new approach to develop therapeutic strategies for prevention of deterioration of cerebral function and for the treatment of stroke.

Show MeSH
Related in: MedlinePlus