Astragaloside IV Alleviates Cerebral Ischemia-Reperfusion Injury through NLRP3 Inflammasome-Mediated Pyroptosis Inhibition via Activating Nrf2.

As one of the fundamental components of Astragalus membranaceus, astragaloside IV (AST IV) exerts protective effects against cerebral ischemia-reperfusion injury (CIRI). Nevertheless, the underlying mechanisms have not yet been conclusively elucidated. To do so, here, we report on the regulatory effects of Nrf2 on NLRP3 inflammasome-mediated pyroptosis. CIRI was induced by middle cerebral artery occlusion-reperfusion (MCAO/R) in Sprague Dawley rats and modeled by oxygen and glucose deprivation/reoxygenation (OGD/R) in SH-SY5Y cells. Cerebral infarct volume and neurological deficit score served as indices to evaluate MCAO/R injury. In addition, the CCK-8 assay was used to assess cell viability, the LDH leakage rate was used as a quantitative index, and propidium iodide (PI) staining was used to visualize cells after OGD/R injury. The NLRP3/Caspase-1/GSDMD pathway, which produces the pores in the cell membrane that are central to the pyroptosis process, was assessed to investigate pyroptosis. Nrf2 activation was assessed by detecting Nrf2 protein levels and immunofluorescence analysis. We show that after MCAO/R of rats, the infarct volume and neurological deficit score of rats were strongly increased, and after OGD/R of cell cultures, cell viability was strongly decreased, and the LDH leakage rate and the proportion of PI-positive cells were strongly increased. In turn, MCAO/R and OGD/R enhanced the protein levels of NLRP3, Caspase-1, IL-1β, GSDMD, and GSDMD-N. Moreover, Nrf2 protein levels increased, and Nrf2 translocation was promoted after CIRI. Interestingly, AST IV (i) reduced the cerebral infarct volume and the neurological deficit score in vivo and (ii) increased the cell viability and reduced the LDH leakage rate and the proportion of PI-positive cells in vitro. AST IV reduced the protein levels of NLRP3, Caspase-1, IL-1β, GSDMD, and GSDMD-N, inhibiting NLRP3 inflammasome-mediated pyroptosis. AST IV also increased the protein levels of Nrf2 and promoted the transfer of Nrf2 to the nucleus, accelerating Nrf2 activation. Particularly revealing was that the Nrf2 inhibitor ML385 partly blocked the above effects of AST IV. Taken together, these results demonstrate that AST IV alleviates CIRI through inhibiting NLRP3 inflammasome-mediated pyroptosis via activating Nrf2.

Xiao L ，Dai Z ，Tang W ，Liu C ，Tang B ... -  《-》

Salvianolic Acids for Injection alleviates cerebral ischemia/reperfusion injury by switching M1/M2 phenotypes and inhibiting NLRP3 inflammasome/pyroptosis axis in microglia in vivo and in vitro.

Ma DC ，Zhang NN ，Zhang YN ，Chen HS ... -  《-》

Aloe-emodin alleviates cerebral ischemia-reperfusion injury by regulating microglial polarization and pyroptosis through inhibition of NLRP3 inflammasome activation.

Li X ，Yao M ，Li L ，Ma H ，Sun Y ，Lu X ，Jing W ，Nie S ... -  《-》

Pretreatment of Indobufen and Aspirin and their Combinations with Clopidogrel or Ticagrelor Alleviates Inflammasome Mediated Pyroptosis Via Inhibiting NF-κB/NLRP3 Pathway in Ischemic Stroke.

Increasing studies showed that several anti-platelet drugs turned out to be a promising strategy for inflammatory response. In this study, we investigated the protective efficiency of pretreatment of indobufen or aspirin combined with clopidogrel or ticagrelor (IACT) on cerebral ischemic injury via NF-κB/NLRP3 pathway. Ischemia/reperfusion (I/R) injury was simulated in vivo by middle cerebral artery occlusion/reperfusion (MCAO/R) model, and rats were pretreated with indobufen and aspirin and their combinations with clopidogrel or ticagrelor respectively. The platelet aggregation, cerebral infarct size, water content, neurological impairment and LDH release were measured. The relative expression of inflammasome mediated pyroptosis was determined by ELISA, RT-PCR, Tunel, Immunofluorescence and Western blotting as appropriate. In vitro, I/R injury was simulated in PC12 cells using oxygen glucose deprivation/reperfusion (OGD/R) and Lipopolysaccharide (LPS) to induce pyroptosis. The effect of combinations were significantly greater than MCAO/R group on decreasing the platelet aggregation, infarct size, brain edema, LDH release and neurologic impairment. LPS aggravated I/R-induced PC12 cell injury, which was significantly suppressed by pretreatment of IACT and Bay11-7082. Mechanistically, IACT alleviated transcriptionally encoded IL-1β, IL-18 and NLRP3 via inhibiting nuclear transportation of NF-κB. Importantly, at protein level, NLRP3, Caspase-1, IL-18, IL-1β and GSDMD were significantly decreased in combination groups both in vivo and vitro. IACT reduce inflammasome mediated pyroptosis in MCAO/R rats and OGD/R PC12 cells through inhibiting NF-κB/NLRP3 signaling pathway, which suggests that drug combination is a protective strategy with clinical potential against I/R-induced injury. Graphical abstract.

Li F ，Xu D ，Hou K ，Gou X ，Lv N ，Fang W ，Li Y ... -  《-》

Vitamin D alleviates neuronal injury in cerebral ischemia-reperfusion via enhancing the Nrf2/HO-1 antioxidant pathway to counteract NLRP3-mediated pyroptosis.

Vitamin D supplementation is reported to have anti-inflammatory and neuroprotective effects during cerebral ischemia-reperfusion injury (CIRI), but the protective mechanism has not been fully elucidated. In this study, rats were given prior administrations of 1,25-vitamin D3 (1,25-VitD3) for a week and subjected to 2 hours of middle cerebral artery occlusion (MCAO) followed by 24 hours of reperfusion. Supplementation with 1,25-VitD3 significantly reduced neurological deficit scores and cerebral infarction areas, and increased surviving neurons. Oxygen-glucose deprivation/reoxygenation (OGD/R)-induced rat cortical neuron cells (RN-C) were subjected to 1,25-VitD3 treatment. Administration of 1,25-VitD3 improved cell viability and inhibited lactate dehydrogenase (LDH) activity and cell apoptosis in OGD/R-stimulated RN-C, as assessed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-h-tetrazolium bromide (MTT) assay, LDH activity assays and TdT-mediated dUTP nick end labeling (TUNEL) staining, respectively. Notably, western blot assay showed that 1,25-VitD3 upregulated nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1) to alleviate oxidative stress, but reduced proteins and inflammatory cytokines related to NLR pyrin domain containing 3 (NLRP3)-mediated pyroptosis, resulting in decreased pyroptosis and neuroinflammation in vivo and in vitro. Transfection of pcDNA-Nrf2 in RN-C also inhibited pyroptosis and OGD/R-induced cell death whereas breakdown of Nrf2 signals destroyed the protective effect of 1,25-VitD3 on OGD/R-stimulated RN-C. In conclusion, 1,25-VitD3 protects neurons against CIRI through activating the antioxidant Nrf2/HO-1 pathway to restrain NLRP3-mediated pyroptosis.

Qiao J ，Ma H ，Chen M ，Bai J ... -  《-》