Caffeic acid alleviates cerebral ischemic injury in rats by resisting ferroptosis via Nrf2 signaling pathway.

There are few effective and safe neuroprotective agents for the treatment of ischemic stroke currently. Caffeic acid is a phenolic acid that widely exists in a number of plant species. Previous studies show that caffeic acid ameliorates brain injury in rats after cerebral ischemia/reperfusion. In this study we explored the protective mechanisms of caffeic acid against oxidative stress and ferroptosis in permanent cerebral ischemia. Ischemia stroke was induced on rats by permanent middle cerebral artery occlusion (pMCAO). Caffeic acid (0.4, 2, 10 mg·kg-1·d-1, i.g.) was administered to the rats for 3 consecutive days before or after the surgery. We showed that either pre-pMCAO or post-pMCAO administration of caffeic acid (2 mg·kg-1·d-1) effectively reduced the infarct volume and improved neurological outcome. The therapeutic time window could last to 2 h after pMCAO. We found that caffeic acid administration significantly reduced oxidative damage as well as neuroinflammation, and enhanced antioxidant capacity in pMCAO rat brain. We further demonstrated that caffeic acid down-regulated TFR1 and ACSL4, and up-regulated glutathione production through Nrf2 signaling pathway to resist ferroptosis in pMCAO rat brain and in oxygen glucose deprivation/reoxygenation (OGD/R)-treated SK-N-SH cells in vitro. Application of ML385, an Nrf2 inhibitor, blocked the neuroprotective effects of caffeic acid in both in vivo and in vitro models, evidenced by excessive accumulation of iron ions and inactivation of the ferroptosis defense system. In conclusion, caffeic acid inhibits oxidative stress-mediated neuronal death in pMCAO rat brain by regulating ferroptosis via Nrf2 signaling pathway. Caffeic acid might serve as a potential treatment to relieve brain injury after cerebral ischemia. Caffeic acid significantly attenuated cerebral ischemic injury and resisted ferroptosis both in vivo and in vitro. The regulation of Nrf2 by caffeic acid initiated the transcription of downstream target genes, which were shown to be anti-inflammatory, antioxidative and antiferroptotic. The effects of caffeic acid on neuroinflammation and ferroptosis in cerebral ischemia were explored in a primary microglia-neuron coculture system. Caffeic acid played a role in reducing neuroinflammation and resisting ferroptosis through the Nrf2 signaling pathway, which further suggested that caffeic acid might be a potential therapeutic method for alleviating brain injury after cerebral ischemia.

Li XN ，Shang NY ，Kang YY ，Sheng N ，Lan JQ ，Tang JS ，Wu L ，Zhang JL ，Peng Y ... -  《-》

Erratum: Eyestalk Ablation to Increase Ovarian Maturation in Mud Crabs.

《Jove-Journal of Visualized Experiments》

BNIP3-mediated mitophagy attenuates hypoxic-ischemic brain damage in neonatal rats by inhibiting ferroptosis through P62-KEAP1-NRF2 pathway activation to maintain iron and redox homeostasis.

As a major contributor to neonatal death and neurological sequelae, hypoxic-ischemic encephalopathy (HIE) lacks a viable medication for treatment. Oxidative stress induced by hypoxic-ischemic brain damage (HIBD) predisposes neurons to ferroptosis due to the fact that neonates accumulate high levels of polyunsaturated fatty acids for their brain developmental needs but their antioxidant capacity is immature. Ferroptosis is a form of cell death caused by excessive accumulation of iron-dependent lipid peroxidation and is closely associated with mitochondria. Mitophagy is a type of mitochondrial quality control mechanism that degrades damaged mitochondria and maintains cellular homeostasis. In this study we employed mitophagy agonists and inhibitors to explore the mechanisms by which mitophagy exerted ferroptosis resistance in a neonatal rat HIE model. Seven-days-old neonatal rats were subjected to ligation of the right common carotid artery, followed by exposure to hypoxia for 2 h. The neonatal rats were treated with a mitophagy activator Tat-SPK2 peptide (0.5, 1 mg/kg, i.p.) 1 h before hypoxia, or in combination with mitochondrial division inhibitor-1 (Mdivi-1, 20 mg/kg, i.p.), and ferroptosis inhibitor Ferrostatin-1 (Fer-1) (2 mg/kg, i.p.) at the end of the hypoxia period. The regulation of ferroptosis by mitophagy was also investigated in primary cortical neurons or PC12 cells in vitro subjected to 4 or 6 h of OGD followed by 24 h of reperfusion. We showed that HIBD induced mitochondrial damage, ROS overproduction, intracellular iron accumulation, lipid peroxidation and ferroptosis, which were significantly reduced by the pretreatment with Tat-SPK2 peptide, and aggravated by the treatment with Mdivi-1 or BNIP3 knockdown. Ferroptosis inhibitors Fer-1 and deferoxamine B (DFO) reversed the accumulation of iron and lipid peroxides caused by Mdivi-1, hence reducing ferroptosis triggered by HI. We demonstrated that Tat-SPK2 peptide-activated BNIP3-mediated mitophagy did not alleviate neuronal ferroptosis through the GPX4-GSH pathway. BNIP3-mediated mitophagy drove the P62-KEAP1-NRF2 pathway, which conferred ferroptosis resistance by maintaining iron and redox homeostasis via the regulation of FTH1, HO-1, and DHODH/FSP1-CoQ10-NADH. This study may provide a new perspective and a therapeutic drug for the treatment of neonatal HIE.

Wang XX ，Li M ，Xu XW ，Zhao WB ，Jin YM ，Li LL ，Qin ZH ，Sheng R ，Ni H ... -  《-》

Ethanol extracts of Cinnamomum migao H.W. Li attenuates neuroinflammation in cerebral ischemia-reperfusion injury via regulating TLR4-PI3K-Akt-NF-κB pathways.

Cinnamomum migao H.W. Li, commonly known as migao (MG), is used in the Miao region of China for treating cardiovascular and cerebrovascular diseases, attributed to its detoxifying (Jiedu in Chinese), activating blood circulation (Huoxue in Chinese), and promoting Qi circulation (Tongqi in Chinese) properties. However, its therapeutic potential for ischemic stroke (IS) remains unexplored. Therefore, this study was to explore the protective effect of MG against cerebral ischemia-reperfusion injury caused by IS. The aim of this study was to investigate whether ethanol extract of MG (EEMG) attenuates cerebral ischemia-reperfusion injury, and explored the underlying mechanisms. Middle cerebral artery occlusion and reperfusion (MCAO/R) was established, and the efficacy of EEMG was evaluated using triphenyltetrazolium chloride (TTC), immunofluorescence, hematoxylin-eosin (HE) staining, and real-time quantitative PCR (qRT-PCR). Qualitative analysis of EEMG was analyzed for chemical composition by liquid chromatography-mass spectrometry (LC-MS). The molecular mechanism of EEMG was explored by metabolomics, network pharmacology, immunoblotting, immunofluorescence staining, gene knockdown, and agonist treatment. The results showed that EEMG alleviates ischemic injury in MCAO/R-operated rats and reduces neuronal damage of OGD/R-treated SH-SY5Y cells. Specifically, EEMG inhibited the release of inflammatory factors and reversed serum metabolic profile disorders of MCAO/R rats. Network pharmacology analysis showed that the PI3K-Akt and NF-κB signaling pathways play a role in the neuroprotective effects of EEMG against ischemic injury and in mitigating the inflammatory response. Consistent with our expectations, EEMG activated PI3K-AKT and suppressed NF-kB signaling pathways both in MCAO/R-operated rats and OGD/R-treated BV2 cells. The results showed that knockdown of TLR4 abolished the EEMG-mediated inhibition on neuroinflammation in OGD/R-treated BV2 cells. After treating BV2 cells with the TLR4 agonist neoseptin 3, EEMG showed a trend toward inhibiting neuroinflammation, though the effect was not statistically significant. Additionally, EEMG was found to improve liver injury caused by cerebral ischemia-reperfusion, which is associated with NF-κB signaling pathway in this study. Collectively, this study demonstrated that EEMG attenuates neuroinflammation in cerebral ischemia-reperfusion injury via regulating TLR4-PI3K-Akt-NF-κB pathways.

Wu W ，Xu L ，Mu D ，Wang D ，Tan S ，Liu L ，Li Y ，Chai H ，Hou Y ... -  《-》

Remimazolam Suppresses Oxidative Stress and Apoptosis in Cerebral Ischemia/Reperfusion Injury by Regulating AKT/GSK-3β/NRF2 Pathway.

The mechanism of remimazolam, a benzodiazepine that activates γ-aminobutyric acid a (GABAa) receptors, in cerebral ischemia/reperfusion (I/R) injury is not well understood. Therefore, we explored whether remimazolam activates protein kinase B (AKT)/glycogen synthase kinase-3β (GSK-3β)/nuclear factor erythroid 2-related factor 2 (NRF2) to attenuate brain I/R injury in transcerebral I/R-injured rats and transoxygenic glucose deprivation/reperfusion (OGD/R)-injured SY5Y cells. Remimazolam was added at the beginning of cell and rat reperfusion, and the PI3K/AKT inhibitor LY294002 was added to inhibit the AKT/GSK-3β/NRF2 pathway 24 h before cellular OGD/R treatment and 30 min before rat brain I/R treatment. The viability and apoptosis rate of SY5Y cells, neurological deficit score, cerebral infarction volume and morphological changes of rat brain cells as well as the protein expression of Bax, Bcl2, Caspase 3, Cleaved-Caspase 3 and the number of TdT-mediated dUTP Nick-End Labeling (TUNEL)-positive cells in the penumbral region were detected. Reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), NRF2, heme oxygenase 1 (HO-1), AKT, P-AKT, GSK-3β, P-GSK-3β protein expression, and nuclear translocation of NRF2 were measured in cell and animal assays. Reduced SY5Y cell viability and increased apoptosis caused by OGD/R injury, elevated neurological deficit scores and cerebral infarct volume induced by brain I/R injury in rats, cerebral cell injury, as well as elevated Bax, Cleaved-Caspase 3, decreased Bcl2, and increased number of TUNEL-positive cells in rat brain tissue were all moderated by remimazolam. Decreased GSH-Px, SOD and Elevated MDA, ROS induced by OGD/R-injured SY5Y cells and brain I/R-injured rats were moderated by remimazolam. Meanwhile, remimazolam increased NRF2, HO-1, P-AKT, P-GSK-3β, and the nuclear accumulation of NRF2. The PI3K/AKT inhibitor LY294002 reversed the role of remimazolam in brain I/R injury. This study demonstrates that remimazolam activates the AKT/GSK-3β/NRF2 pathway, thereby attenuating oxidative stress and apoptosis to protect against brain I/R injury.

Duan M ，Yu N ，Liu J ，Zhao Y ，Zhang J ，Song S ，Wang S ... -  《Drug Design Development and Therapy》