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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 expression of NOD2 in wild type (WT) mice was increased after cerebral ischemia-reperfusion injury. (A) Relative quantitative mRNA levels of NOD2 were determined by real-time RT-PCR analysis in penumbral cortex from WT mice after 2 h occlusion of the middle cerebral artery (MCAO) and 2 h, 6 h, 12 h, 24 h, 48h reperfusion. (B) Western blot analysis of NOD2 protein levels in the penumbral cortex from WT mice after 2 h MCAO and 2 h, 6 h, 12 h, 24 h and 48 h reperfusion. Results are representative of six independent experiments. *P<0.05, I/R WT mice vs. sham-operated WT mice. (C) Representative images of double immunolabeling for NOD2 and glial fibrillary acidic protein antibody (GFAP, astrocyte marker), CD11b (myeloid cell marker), Iba-1 (microglial/macrophage marker) or NeuN antibody (neuron marker) in the penumbral cortex from WT mice after 2 h MCAO and 24 h reperfusion. DAPI indicates 4',6-diamidino-2-phenylindole. Scale bars: 50 μm.
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Figure 1: The expression of NOD2 in wild type (WT) mice was increased after cerebral ischemia-reperfusion injury. (A) Relative quantitative mRNA levels of NOD2 were determined by real-time RT-PCR analysis in penumbral cortex from WT mice after 2 h occlusion of the middle cerebral artery (MCAO) and 2 h, 6 h, 12 h, 24 h, 48h reperfusion. (B) Western blot analysis of NOD2 protein levels in the penumbral cortex from WT mice after 2 h MCAO and 2 h, 6 h, 12 h, 24 h and 48 h reperfusion. Results are representative of six independent experiments. *P<0.05, I/R WT mice vs. sham-operated WT mice. (C) Representative images of double immunolabeling for NOD2 and glial fibrillary acidic protein antibody (GFAP, astrocyte marker), CD11b (myeloid cell marker), Iba-1 (microglial/macrophage marker) or NeuN antibody (neuron marker) in the penumbral cortex from WT mice after 2 h MCAO and 24 h reperfusion. DAPI indicates 4',6-diamidino-2-phenylindole. Scale bars: 50 μm.

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 expression of NOD2 in wild type (WT) mice was increased after cerebral ischemia-reperfusion injury. (A) Relative quantitative mRNA levels of NOD2 were determined by real-time RT-PCR analysis in penumbral cortex from WT mice after 2 h occlusion of the middle cerebral artery (MCAO) and 2 h, 6 h, 12 h, 24 h, 48h reperfusion. (B) Western blot analysis of NOD2 protein levels in the penumbral cortex from WT mice after 2 h MCAO and 2 h, 6 h, 12 h, 24 h and 48 h reperfusion. Results are representative of six independent experiments. *P<0.05, I/R WT mice vs. sham-operated WT mice. (C) Representative images of double immunolabeling for NOD2 and glial fibrillary acidic protein antibody (GFAP, astrocyte marker), CD11b (myeloid cell marker), Iba-1 (microglial/macrophage marker) or NeuN antibody (neuron marker) in the penumbral cortex from WT mice after 2 h MCAO and 24 h reperfusion. DAPI indicates 4',6-diamidino-2-phenylindole. Scale bars: 50 μm.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4400384&req=5

Figure 1: The expression of NOD2 in wild type (WT) mice was increased after cerebral ischemia-reperfusion injury. (A) Relative quantitative mRNA levels of NOD2 were determined by real-time RT-PCR analysis in penumbral cortex from WT mice after 2 h occlusion of the middle cerebral artery (MCAO) and 2 h, 6 h, 12 h, 24 h, 48h reperfusion. (B) Western blot analysis of NOD2 protein levels in the penumbral cortex from WT mice after 2 h MCAO and 2 h, 6 h, 12 h, 24 h and 48 h reperfusion. Results are representative of six independent experiments. *P<0.05, I/R WT mice vs. sham-operated WT mice. (C) Representative images of double immunolabeling for NOD2 and glial fibrillary acidic protein antibody (GFAP, astrocyte marker), CD11b (myeloid cell marker), Iba-1 (microglial/macrophage marker) or NeuN antibody (neuron marker) in the penumbral cortex from WT mice after 2 h MCAO and 24 h reperfusion. DAPI indicates 4',6-diamidino-2-phenylindole. Scale bars: 50 μm.
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