Downregulation of Nogo-B ameliorates cerebral ischemia/reperfusion injury in mice through regulating microglia polarization via TLR4/NF-kappaB pathway.

Many studies have shown a close association between Nogo-B and inflammation-related diseases. However, uncertainty does exist, regarding Nogo-B function in the pathological progression of cerebral ischemia/reperfusion (I/R) injury. Middle cerebral artery occlusion/reperfusion (MCAO/R) model was utilized in C57BL/6L mice to mimic ischemic stroke in vivo. Using oxygen-glucose deprivation and reoxygenation (ODG/R) model in microglia cells (BV-2) to establish cerebral I/R injury in vitro. Various methods, including Nogo-B siRNA transfection, mNSS and the rotarod test, TTC, HE and Nissl staining, immunofluorescence staining, immunohistochemistry, Western blot, ELISA, TUNEL and qRT-PCR were employed to probe into the effect of Nogo-B downregulation on cerebral I/R injury and the potential mechanisms. A small amount of Nogo-B expression (protein and mRNA) was observed in cortex and hippocampus before ischemia, then Nogo-B expression increased significantly on day 1, reaching the maximum on day 3, remaining stable on day 14 after I/R, and decreasing gradually after 21 days, but it still rose significantly compared with that observed preischemia. Nogo-B down-regulation could markedly reduce the neurological score and infarct volume, improve the histopathological changes and neuronal apoptosis, lower the number of CD86+/Iba1+ cells and the levels of IL-1β, IL-6, and TNF-α, and raise the density of NeuN fluorescence, the number of CD206+/Iba1+ cells, and the level of IL-4, IL-10 and TGF-β in brain of MCAO/R mice. Treatment with Nogo-B siRNA or TAK-242 in BV-2 cells could obviously decrease the CD86 fluorescence density and the mRNA expression of IL-1β, IL-6 and TNF-α, increase CD206 fluorescence density and the mRNA expression of IL-10 after OGD/R injury. In addition, the expression of TLR4, p-IκBα and p-p65 proteins significantly increased in the brain after MCAO/R and BV-2 cells exposed to OGD/R. Treatment with Nogo-B siRNA or TAK-242 prominently reduced the expression of TLR4, p-IκBα and p-p65. Our findings suggest that the down-regulation of Nogo-B exerts protective effect on cerebral I/R injury by modulating the microglia polarization through inhibiting TLR4/NF-κB signaling pathway. Nogo-B may be a potential therapeutic target for ischemic stroke.

Gong P ，Jia HY ，Li R ，Ma Z ，Si M ，Qian C ，Zhu FQ ，Sheng-Yong L ... -  《-》

Qingda granule alleviates cerebral ischemia/reperfusion injury by inhibiting TLR4/NF-κB/NLRP3 signaling in microglia.

Cai Q ，Zhao C ，Xu Y ，Lin H ，Jia B ，Huang B ，Lin S ，Chen D ，Jia P ，Wang M ，Lin W ，Zhang L ，Chu J ，Peng J ... -  《-》

Neuroprotective Effects of Hesperetin in Regulating Microglia Polarization after Ischemic Stroke by Inhibiting TLR4/NF-κB Pathway.

This study aimed to explore the influence of hesperidin on the polarization of microglia to clarify the key mechanism of regulating the polarization of M2 microglia. C57BL/6 mice were randomly divided into middle cerebral artery occlusion model group (MCAO group), MCAO + hesperidin treatment group (MCAO + hesperidin group), and sham group (sham operation group). The mice were assessed with neurological scores for their functional status. 2,3,5-Triphenyltetrazole chloride (TTC) was used to determine the volume of cerebral infarction. Hematoxylin and eosin (H&E) staining was performed to detect brain loss. The system with 1% O2, 5% CO2, and 92% N2 was applied to establish BV2 in vitro model induced by MCAO. TNF-α, IL-1β, TGF-β, and IL-10 levels of cytokines in the supernatant were detected by ELISA. RT-qPCR was used to detect mRNA levels of M1 iNOS, CD11b, CD32, and CD86, and mRNA levels of M2 CD206, Arg-1, and TGF-β. The Iba-1, iNOS, and Arg-1 of microglia and protein levels of TLR4 and p-NF-κB related to the pathway were detected by Western blot. After treatment with hesperidin, BV2 cells induced by MCAO in vitro can reduce the proinflammatory cytokines of TNF-α and IL-1β significantly, further upregulating anti-inflammatory cytokines of TGF-β, IL-10 while inhibiting TLR4 and p-NF-κB expression. The MCAO-induced BV2 cells treated by TLR-4 inhibitor TAK-242 and NF-κB inhibitor BAY 11-7082 had similar polarization effects to those treated with hesperidin. This study found that hesperetin gavage treatment can improve the neurological deficit and regulate the polarization of microglia in MCAO mice. In vitro experiments further verified that hesperidin plays a neuroprotective role by inhibiting the TLR4-NF-κB pathway, thus providing new targets and strategies for neuroprotection and nerve repair after ischemic stroke.

Zhang J ，Jiang H ，Wu F ，Chi X ，Pang Y ，Jin H ，Sun Y ，Zhang S ... -  《-》

Intermittent theta-burst stimulation improves motor function by inhibiting neuronal pyroptosis and regulating microglial polarization via TLR4/NFκB/NLRP3 signaling pathway in cerebral ischemic mice.

Neuronal pyroptosis and neuroinflammation with excess microglial activation are widely involved in the early pathological process of ischemic stroke. Repetitive transcranial magnetic stimulation (rTMS), as a non-invasive neuromodulatory technique, has recently been reported to be anti-inflammatory and regulate microglial function. However, few studies have elucidated the role and mechanism of rTMS underlying regulating neuronal pyroptosis and microglial polarization. We evaluated the motor function in middle cerebral artery occlusion/reperfusion (MCAO/r) injury mice after 1-week intermittent theta-burst rTMS (iTBS) treatment in the early phase with or without depletion of microglia by colony-stimulating factor 1 receptor (CSF1R) inhibitor treatment, respectively. We further explored the morphological and molecular biological alterations associated with neuronal pyroptosis and microglial polarization via Nissl, EdU, TTC, TUNEL staining, electron microscopy, multiplex cytokine bioassays, western blot assays, immunofluorescence staining and RNA sequencing. ITBS significantly protected against cerebral ischemia/reperfusion (I/R) injury-induced locomotor deficits and neuronal damage, which probably relied on the regulation of innate immune and inflammatory responses, as evidenced by RNA sequencing analysis. The peak of pyroptosis was confirmed to be later than that of apoptosis during the early phase of stroke, and pyroptosis was mainly located and more severe in the peri-infarcted area compared with apoptosis. Multiplex cytokine bioassays showed that iTBS significantly ameliorated the high levels of IL-1β, IL-17A, TNF-α, IFN-γ in MCAO/r group and elevated the level of IL-10. ITBS inhibited the expression of neuronal pyroptosis-associated proteins (i.e., Caspase1, IL-1β, IL-18, ASC, GSDMD, NLRP1) in the peri-infarcted area rather than at the border of infarcted core. KEGG enrichment analysis and further studies demonstrated that iTBS significantly shifted the microglial M1/M2 phenotype balance by curbing proinflammatory M1 activation (Iba1+/CD86+) and enhancing the anti-inflammatory M2 activation (Iba1+/CD206+) in peri-infarcted area via inhibiting TLR4/NFκB/NLRP3 signaling pathway. Depletion of microglia using CSF1R inhibitor (PLX3397) eliminated the motor functional improvements after iTBS treatment. rTMS could alleviate cerebral I/R injury induced locomotor deficits and neuronal pyroptosis by modulating the microglial polarization. It is expected that these data will provide novel insights into the mechanisms of rTMS protecting against cerebral I/R injury and potential targets underlying neuronal pyroptosis in the early phase of stroke.

Luo L ，Liu M ，Fan Y ，Zhang J ，Liu L ，Li Y ，Zhang Q ，Xie H ，Jiang C ，Wu J ，Xiao X ，Wu Y ... -  《Journal of Neuroinflammation》

Anti-inflammatory effects of quinolinyl analog of resveratrol targeting TLR4 in MCAO/R ischemic stroke rat model.

Among adults, stroke is the main causes of mortality and permanent disability. Neuroinflammation is one of the main causes of stoke-mediated neuronal death. Our previous study revealed that (E)-5-(2-(Quinolin-4-yl) vinyl) benzene-1, 3-diol (RV01), a quinolinyl analog of resveratrol, inhibits microglia-induced neuroinflammation and safeguards neurons from inflammatory harm. The preventive role of RV01 in ischemic stroke and its underlying cellular mechanisms and molecular targets remain poorly understood. To investigate whether RV01 alleviates ischemia-reperfusion (I/R) injury by inhibiting microglia-mediated neuroinflammation and determine the potential molecular mechanisms and targets by which RV01 inhibits the I/R-mediated microglia activation. Rat middle cerebral artery occlusion and reperfusion (MCAO/R) and BV-2 or primary microglial cells oxygen-glucose deprivation and reperfusion (OGD/R) models were established. The neurological behavior scores, 2, 3, 5-triphenyl tetrazolium chloride staining and immunofluorescence were used to detect the neuroprotective effect of RV01 in the MCAO/R rats. In addition, the mRNA expression levels of IL-6, TNF-α, and IL-1β were detected to reveal the antineuroinflammatory effect of RV01. Moreover, a western blot assay was performed to explore the protein expression changes in NF-κB-mediated neuroinflammation. Finally, we identified TLR4 as an RV01 target through molecular docking, drug sensitivity target stability analysis, cellular thermal shift analysis, and surface plasmon resonance techniques. RV01 reduced the infarct volume and neurological deficits, increased the rotarod duration, and decreased the number of rightward deflections in the MCAO/R rats. RV01 inhibited the NF-κB signaling pathway in vitro and in vivo, as demonstrated by the reduction in the transcription factor p65-mediated expression of several inflammatory factors including IL-6, TNF-α, and IL-1β. Further studies showed that its protective effect was associated with targeting the TLR4 protein. Notably, the anti-inflammatory effect of RV01 was markedly reinforced by the TLR4 knockdown, but inhibited by the overexpression of TLR4. Results revealed that the conditioned medium derived from the RV01-treated BV-2 cells significantly decreased the OGD/R-mediated neuronal damage. Our results are the first to reveal the protective effects of RV01 on cerebral ischemia, depending on its inhibitory effect on the NF-κB pathway by targeting TLR4. RV01 could be a potential protective agent in ischemic stroke treatment.

Xu L ，Mi Y ，Meng Q ，Liu Y ，Wang F ，Zhang G ，Liu Y ，Chen G ，Hou Y ... -  《-》