Americanin B inhibits pyroptosis in lipopolysaccharide-induced septic encephalopathy mice through targeting NLRP3 protein.

BACKGROUND: Sepsis is considered as a severe illness due to its high mortality. Sepsis can cause septic encephalopathy, thus leading to brain injury, behavioral and cognitive dysfunction. Pyroptosis is a type of regulated cell death (RCD) and takes a crucial part in occurrence and development of sepsis. Americanin B (AMEB) is a lignan compounds, which is extracted from Vernicia fordii. In our previous study, AMEB could inhibit microglial activation in inflammatory cell model. However, the function of AMEB in septic encephalopathy mice is uncertain. It would be worthwhile to ascertain the role and mechanism of AMEB in sepsis. PURPOSE: Current study designs to certify the relationship between pyroptosis and septic encephalopathy, and investigate whether AMEB can restrain NOD-like receptor pyrin domain-containing 3 (NLRP3) inflammasome activation and restrict pyroptosis by targeting NLRP3 in septic mice model. STUDY DESIGN: C57BL/6 mice were utilized to perform sepsis model in vivo experiments. BV-2 cell lines were used for in vitro experiments. METHODS: In vivo sepsis model was established by lipopolysaccharide (LPS) intraperitoneal injection in male C57BL/6 J mice and in vitro model was exposed by LPS plus ATP in BV-2 cells. The survival rate was monitored on the corresponding days. NLRP3, apoptosis associated Speck-like protein (ASC), caspase-1, GasderminD (GSDMD), interleukin-1ß (IL-1ß) and interleukin-18 (IL-18) level were detected by western blotting and immunofluorescence analysis. Molecular docking, cellular thermal shift assay (CETSA), drug affinity responsive target stability (DARTS) experiments, RNAi transfection and quantitative real-time PCR were applied to confirm the potential target of AMEB. RESULTS: The results suggested that AMEB could rise survival percentage and lighten brain injury in LPS-induced sepsis mice. In addition, AMEB could inhibit pyroptosis and the activiation of NLRP3 inflammasome. The inhibiting function of AMEB on the activiation of NLRP3 inflammasome is weakened following si-NLRP3 transfection. Moreover, AMEB exerted anti-pyroptosis effect via targeting NLRP3 protein. CONCLUSIONS: Our findings first indicate NLRP3 is an effective druggable target for septic encephalopathy related brain injury, and also provide a candidate-AMEB for the treatment of septic encephalopathy. These emerging findings on AMEB in models of sepsis suggest an innovative approach that may be beneficial in the prevention of septic encephalopathy.

Crebanine ameliorates ischemia-reperfusion brain damage by inhibiting oxidative stress and neuroinflammation mediated by NADPH oxidase 2 in microglia.

BACKGROUND: The urgent challenge for ischemic stroke treatment is the lack of effective neuroprotectants that target multiple pathological processes. Crebanine, an isoquinoline-like alkaloid with superior pharmacological activities, presents itself as a promising candidate for neuroprotection. However, its effects and mechanisms on ischemic stroke remain unknown. METHODS: The effects of crebanine on brain damage following ischemic stroke were evaluated using the middle cerebral artery occlusion and reperfusion (MCAO/R) model. Mechanism of action was investigated using both MCAO/R rats and lipopolysaccharide (LPS)-activated BV-2 cells. RESULTS: We initially demonstrated that crebanine effectively ameliorated the neurological deficits in MCAO/R rats, while also reducing brain edema and infarction. Treatment with crebanine resulted in the up-regulation of NeuN+ fluorescence density and down-regulation of FJB+ cell count, and mitigated synaptic damage. Crebanine attenuated the hyperactivation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2) by downregulating NADP+ and NADPH levels, suppressing gp91phox and p47phox expressions, and reducing p47phox membrane translocation in Iba-1+ cells. Additionally, crebanine reduced the quantity of Iba-1+ cells and protein expression. Correlation analysis has demonstrated that the inhibition of NOX2 activation in microglia is beneficial for mitigating I/R brain injuries. Moreover, crebanine exhibited significant antioxidant properties by down-regulating the expression of superoxide anion and intracellular reactive oxygen species in vivo and in vitro, and reducing lipid and DNA peroxidation. Crebanine exerted anti-inflammatory effect, as evidenced by the reduction in the expressions of nitric oxide, interleukin 1ß, tumor necrosis factor α, interleukin 6, and inducible nitric oxide synthase. The effect of crebanine was achieved through the suppression of nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases (MAPK) signaling pathway. This is supported by evidence showing reduced NF-κB p65 promoter activity and nucleus translocation, as well as suppressed IκBα phosphorylation and degradation. Additionally, it inhibited the phosphorylation of ERK, JNK, and p38 MAPKs. Importantly, the anti-oxidative stress and neuroinflammation effects of crebanine were further enhanced after silencing gp91phox and p47phox. CONCLUSION: Crebanine alleviated the brain damages of MCAO/R rats by inhibiting oxidative stress and neuroinflammation mediated by NOX2 in microglia, implying crebanine might be a potential natural drug for the treatment of cerebral ischemia.

Isoamericanin A improves lipopolysaccharide-induced memory impairment in mice through suppression of the nicotinamide adenine dinucleotide phosphateoxidase-dependent nuclear factor kappa B signaling pathway.

Alzheimer's disease (AD) is the most frequent cause of dementia in the elderly. Isoamericanin A (ISOA) is a natural lignan possessing great potential for AD treatment. This study investigated the efficacy of ISOA on memory impairments in the mice intrahippocampal injected with lipopolysaccharide (LPS) and the underlying mechanism. Y-maze and Morris Water Maze data suggested that ISOA (5 and 10 mg/kg) ameliorated short- and long-term memory impairments, and attenuated neuronal loss and lactate dehydrogenase activity. ISOA exerted anti-inflammatory effect demonstrating by the reduction of ionized calcium-binding adapter molecule 1 positive cells and suppression of marker protein and pro-inflammation cytokines expressions induced by LPS. ISOA suppressed the nuclear factor kappa B (NF-κB) signaling pathway by inhibiting IκBα phosphorylation and NF-κB p65 phosphorylation and nuclear translocation. ISOA inhibited superoxide and intracellular reactive oxygen species accumulation by reducing nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation, demonstrating by suppressing NADP+ and NADPH contents, gp91phox expression, and p47phox expression and membrane translocation. These effects were enhanced in combination with NADPH oxidase inhibitor apocynin. The neuroprotective effect of ISOA was further proved in the in vitro models. Overall, our data revealed a novel pharmacological activity of ISOA: ameliorating memory impairment in AD via inhibiting neuroinflammation.

Investigation of Molecular Mechanisms of Polyvinylidene Fluoride under the Effects of Temperature, Electric Poling, and Mechanical Stretching Using Molecular Dynamics Simulations.

This study uses molecular dynamics (MD) simulations to investigate the molecular mechanisms of polyvinylidene fluoride (PVDF) influenced by temperature, electric poling, and mechanical stretching. The ß-phase, with all-trans ⟨T⟩ planar zigzag conformation, is known to have the best potential of energy harvesting, while α-phase, with alternating trans ⟨T⟩ and gauche ⟨G⟩ linkages, is more stable in terms of potential energy. By applying an electric field and uniaxial deformation to an amorphous PVDF system, we study the transformation from α- to ß-phase and corresponding molecular mechanisms by tracking the molecular chain conformation using the trans percentages (PT). After complete relaxation of molecular chains, the chain conformations and PT values indicate a typical distribution pattern of α-phase. Next, we observe that the dipole moment of the system increases significantly with the presence of a strong electric field without immediately affecting the chain conformations. The increment of dipole moment is due to the aligning of side atoms within the chains and the increment becomes more significant with elevated temperature. In contrast, chain conformations change significantly under mechanical stretching. Specifically, before yielding, the total dipole moments are still governed by local orientations of atoms. Later, the chain segments begin to straighten in the large deformation stage, which leads to the increment of the total dipole moment. Our results also show that there exists an optimal temperature window for maximum ⟨G⟩ to ⟨T⟩ transformation rate. Moreover, we look into the synergistic effect of electric poling and mechanical stretching and explain molecular-level mechanisms for this effect. This study contributes to the fundamental understanding of the underlying molecular mechanisms for the piezoelectric PVDF system under different processing conditions.

Anti-neuroinflammatory effects in vitro and in vivo, and chemical profile of Jatropha curcas L.

The ethyl acetate extract of the stems of Jatropha curcas (ESJ) exerted prominent anti-neuroinflammatory effect through inhibiting microglial overactivation, and reducing mRNA expression of inflammatory factors, including nitric oxide (NO), inducible nitric oxide synthase, and interleukin-1ß in the cortex and the formation of NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasomes in C57BL/6 mice. Phytochemical research afforded twenty-three major constituents, including five undescribed components (diterpenes 1-3, 7 and a triterpene 18) and a new natural product [a diterpene, (3S,5S,10R)-3-hydroxy-12-methoxy-13-methylpodopcarpa-8,11,13-trien-7-one (8)], by comprehensive analysis of spectroscopic data. Bioassay showed that ESJ (IC50: 6.49 µg/mL), diterpenes 1, 5, 12, 14, 15, 17, triterpenes 18, 19, preussomerin 22, and lactone 23 (IC50 values from 0.10 to 49.05 µM) inhibited NO production more strongly than the positive control in lipopolysaccharide-stimulated BV-2 cells. HPLC experiment further substantiated that 1, 5, 12, 14-15, 17-19, 22-23 are the characteristic constituents of ESJ, suggesting they might possess the potential for the treatment of neuroinflammation.

Potential inhibitors of microglial activation from the roots of Vernicia montana Lour.

During our continuous investigation of natural, herbal inhibitors of microglial over-activation in the Euphorbiaceae family, two plants of the Vernicia genus showed remarkable inhibitory effects on nitric oxide (NO) production in over-activated microglia. In this study, bioactivity-guided phytochemical research on the active fraction of the roots of V. montana was carried out. As a result, seven undescribed terpenoids and lignans, together with thirty-one known components, were isolated and identified using comprehensive spectral analysis. All the identified compounds were evaluated for their inhibitory effects on NO production in lipopolysaccharide-stimulated BV-2 cells. Combined with our previous research on the Vernicia genus, the effective material basis of different plants and medicinal components was analyzed systematically.

Crack propagation in graphene monolayer under tear loading.

Crack propagation in graphene monolayer under tear loading is investigated via an energy-based analytical model and molecular dynamics (MD) simulations. The classical mechanics-based model describes steady-state crack propagation velocity as a function of applied stress, lateral dimension and loading geometry, as well as the critical stress and critical size for initiating steady crack propagation. MD simulations reveal that cracks propagate along the zigzag direction but yield different "fracture surface" roughnesses for different loading geometries. MD simulations and the predictions of the analytical model are in excellent agreement. Our findings lead to an improved fundamental understanding of the mode-III crack of monolayer graphene necessary for the design and fabrication of graphene-based devices.