Astilbin protects against cerebral ischaemia/reperfusion injury by inhibiting cellular apoptosis and ROS-NLRP3 inflammasome axis activation

Forsythoside B alleviates cerebral ischemia-reperfusion injury via inhibiting NLRP3 inflammasome mediated by SIRT1 activation

BACKGROUND

The inflammatory response is a key factor in the pathogenesis of cerebral ischemia/reperfusion injury (CIRI), and anti-inflammatory interventions may offer a promising therapeutic strategy. Forsythoside B (FB) is a phenylethanoid glycoside isolated from Forsythiae fructus, which has been reported to have anti-inflammatory effects. However, the mechanism of the neuroprotective effect of FB on CIRI remains unclear.

METHODS

Adult male Sprague-Dawley rats were subjected to transient middle cerebral artery occlusion/reperfusion (MCAO/R). FB was administered intraperitoneally for 3 days prior to MCAO/R. Cerebral infarct volume and neurological deficit score were used as indices to evaluate MCAO/R injury. The serum levels of inflammatory factors and antioxidant enzymes were measured. The activation of silent information regulator 2 homolog 1 (Sirt1) and the inhibition of the nucleotide-binding oligomerization domain-like receptor with a pyrin domain 3 (NLRP3) pathway were assessed through western blot and immunohistochemistry analysis. Furthermore, the rats were treated with Sirt1 shRNA 3 days before MCAO/R by stereotactical injection into the ipsilateral hemispheric region to assess the impact of Sirt1 knockdown on the protection of FB during MCAO/R.

RESULTS

FB reduced cerebral infarct volume and neurological deficit score in MCAO/R rats. FB reduced pathological changes and cell apoptosis in the hippocampal CA1 region and cortex on the ischemic side of rats. FB inhibited the serum levels of inflammatory factors and increased the activities of antioxidant enzymes. Further study showed that FB inhibited the activation of the NLRP3 pathway and induced Sirt1 activation.

CONCLUSION

FB demonstrated neuroprotective and anti-inflammatory effects by inhibiting the NLRP3 pathway through Sirt1 activation in CIRI.

Novel insight into the therapeutical potential of flavonoids from traditional Chinese medicine against cerebral ischemia/reperfusion injury

Cerebral ischemia/reperfusion injury (CIRI) is a major contributor to poor prognosis of ischemic stroke. Flavonoids are a broad family of plant polyphenols which are abundant in traditional Chinese medicine (TCM) and have beneficial effects on several diseases including ischemic stroke. Accumulating studies have indicated that flavonoids derived from herbal TCM are effective in alleviating CIRI after ischemic stroke in vitro or in vivo, and exhibit favourable therapeutical potential. Herein, we systematically review the classification, metabolic absorption, neuroprotective efficacy, and mechanisms of TCM flavonoids against CIRI. The literature suggest that flavonoids exert potential medicinal functions including suppressing excitotoxicity, Ca2+ overloading, oxidative stress, inflammation, thrombin's cellular toxicity, different types of programmed cell deaths, and protecting the blood-brain barrier, as well as promoting neurogenesis in the recovery stage following ischemic stroke. Furthermore, we identified certain matters that should be taken into account in future research, as well as proposed difficulties and opportunities in transforming TCM-derived flavonoids into medications or functional foods for the treatment or prevention of CIRI. Overall, in this review we aim to provide novel ideas for the identification of new prospective medication candidates for the therapeutic strategy against ischemic stroke.

Selective biosynthesis of a rhamnosyl nosiheptide by a novel bacterial rhamnosyltransferase

Nosiheptide (NOS) is a thiopeptide antibiotic produced by the bacterium Streptomyces actuosus. The hydroxyl group of 3-hydroxypyridine in NOS has been identified as a promising site for modification, which we therefore aimed to rhamnosylate. After screening, Streptomyces sp. 147326 was found to regioselectively attach a rhamnosyl unit to the 3-hydroxypyridine site in NOS, resulting in the formation of a derivative named NOS-R at a productivity of 24.6%. In comparison with NOS, NOS-R exhibited a 17.6-fold increase in aqueous solubility and a new protective effect against MRSA infection in mice, while maintaining a similar in vitro activity. Subsequently, SrGT822 was identified as the rhamnosyltransferase in Streptomyces sp. 147326 responsible for the biosynthesis of NOS-R using dTDP-L-rhamnose. SrGT822 demonstrated an optimal reaction pH of 10.0 and temperature of 55°C, which resulted in a NOS-R yield of 74.9%. Based on the catalytic properties and evolutionary analysis, SrGT822 is anticipated to be a potential rhamnosyltransferase for use in the modification of various complex scaffolds.

Lipid Carrier Nanostructured Astilbin Ameliorates Rotenone-Induced Neurodegeneration in Mice Brain via Modulation of GSK3β-Nrf2 Signaling Pathways

Astilbin is a flavanonol, found in St John's wort (Hypericum perforatum) and many other plants. It has been demonstrated that astilbin contains anti-inflammatory, antioxidant, and immune-suppressive properties. However, the bioavailability of astilbin remains a question for which drug delivery-based nanoparticles can be utilized. We formulated a nanostructured lipid carrier loaded with astilbin (NLC-AS) and tested its effects on the rotenone exposed PC12 cells and in a neurodegenerative mice model of Parkinson's disease (PD) induced by rotenone. Results show that rotenone caused dose-dependent inhibition of PC12 cell growth with about 50% cell death at 2 µM rotenone. Rotenone caused apoptosis in PC12 cells which was reduced to a notable level by NLC-AS through suppression of oxidative stress, especially via elevation of GSH and total antioxidant capacity, and inhibition of monoamine oxidase. Rotenone significantly augmented neurodegeneration in mouse brains by triggering apoptosis and oxidative damage, while NLC-AS treatment halted these processes. Rotenone-exposed mice showed neuronal deficits and impaired neurocognitive functions like loss of memory and learning restrictions which were restored to a remarkable level by NLC-AS administration. The protective effect of NLC-AS was mediated through the inhibition of GSK3β and induction of Nrf2 genes in the brain tissues. These findings suggest that NLC-AS administration may efficiently regulate the signs of PD in mice and prevent neurodegeneration and neurocognitive dysfunctions.

TREM2 mitigates NLRP3-mediated neuroinflammation through the NF-κB and PI3k/Akt signaling pathways in juvenile rats exposed to ambient particulate matter

Ambient particulate matter (PM) is a global public and environmental problem. PM is closely associated with several neurological disorders that typically involve neuroinflammation. There have been few studies on the effect of PM on neuroinflammation to date. In this study, we used a juvenile rat model (PM exposure was conducted at a dose of 10 mg/kg body weight per day for 4 weeks) and a BV-2 cell model (PM exposure was conducted at concentrations of 50, 100, 150, and 200 μg/ml for 24 h) to investigate PM-induced neuroinflammation mediated by NLRP3 inflammasome activation and the role of TREM2 in this process. Our findings revealed that PM exposure reduced TREM2 protein and mRNA levels in the rat hippocampus and BV-2 cells. TREM2 overexpression attenuated PM-induced spatial learning and memory deficits in rats. Moreover, we observed that TREM2 overexpression in vivo and in vitro effectively mitigated the increase in NLRP3 and pro-Caspase1 protein expression, as well as the secretion of IL-1β and IL-18. Exposure to PM increased the expression of NF-κB and decreased the phosphorylation of PI3k/Akt in vivo and in vitro, and this process was effectively reversed by overexpressing TREM2. Our results indicated that PM exposure could reduce TREM2 expression and induce NLRP3 inflammasome-mediated neuroinflammation and that TREM2 could mitigate NLRP3 inflammasome-mediated neuroinflammation by regulating the NF-κB and PI3k/Akt signaling pathways. These findings shed light on PM-induced neuroinflammation mechanisms and potential intervention targets.

Radioprotective efficacy of Astilbin in mitigating radiation-induced lung injury through inhibition of p53 acetylation

Radiation-induced lung injury (RILI) is a common side effect in thoracic tumor patients undergoing radiotherapy. At present, there is no ideal radio-protective agent which is widely used in RILI treatment. Astilbin (AST), a bioactive flavonoid, exhibits various biological effects, including anti-inflammatory, antioxidant, and anti-fibrotic activities, which partly result from reducing oxidative stress and inflammation in various pathogenic conditions. However, the protective efficacy of AST to ameliorate RILI has not been reported. In this study, we employed network pharmacology, RNA sequencing, and experimental evaluation to reveal the effects and pharmacological mechanism of AST to treat RILI in vivo and in vitro. We observed that AST reduced radiation-induced apoptosis, DNA damage, inflammatory reactions, and the reactive oxygen species (ROS) level in human normal lung epithelial cells BEAS-2B. Further study showed that AST treatment significantly ameliorated RILI by reducing the radiation-induced pathology changes and inflammatory reaction of lung tissue in C57BL/6J mice. Mechanistically, the expression of epithelial-mesenchymal transition (EMT) markers and radiation-triggered acetylation of the p53 protein were alleviated by AST treatment. Furthermore, AST alleviated the acetylation of p53 after intervention of Trichostatin A (TSA). Our data indicate that AST can alleviate RILI by inhibiting inflammatory reactions and the EMT process through decreasing the expression of p53 acetylation. In conclusion, our study suggests that AST has great potential to be a new protective and therapeutic compound for RILI.

Polyphenols as NLRP3 inflammasome modulators in cardiometabolic diseases: a review of in vivo studies

The nucleotide-binding domain and leucine-rich repeat containing receptors (NLRs) are components of the innate immune system, important in coordinating the inflammatory response. Among them, NLRP3 can form inflammasomes, multiprotein complexes activating the inflammatory caspase-1 and leading, through a cell death-mediated signaling cascade, to the release of several proinflammatory cytokines. Dietary polyphenols, plant secondary metabolites, have been reported to exhibit anti-inflammatory properties, although studies have focused most on their effect on the expression of the final circulating cytokines rather than on the upstream signals activating the NLRP3 inflammasome. The present review explores current knowledge on the potential of dietary polyphenols to regulate the whole NLRP3 inflammasome pathway, in the context of cardiometabolic pathologies (obesity, cardiovascular diseases, type 2 diabetes and non-alcoholic fatty liver disease), based on in vivo studies. A clear tendency towards a decrease in the expression of the whole NLRP3 inflammasome signaling pathway when several animal models were supplemented with polyphenols was observed, commonly showing a dose-response effect; these modifications were concomitant with clinical improvements in the pathologies. Nevertheless, the diversity of doses used, the disparity in polyphenol structures tested and, particularly, the scarce clinical trials and exploration of mechanisms of action show the need to develop further research on the topic.

Comparative study of the interaction mechanism of astilbin, isoastilbin, and neoastilbin with CYP3A4

The interactions of human CYP3A4 with three selected isomer flavonoids, such as astilbin, isoastilbin and neoastilbin, were clarified using spectral analysis, molecular docking, and molecular dynamics simulation. During binding with the three flavonoids, the intrinsic fluorescence of CYP3A4 was statically quenched in static mode with nonradiative energy conversion. The fluorescence and ultraviolet/visible (UV/vis) data revealed that the three flavonoids had a moderate and stronger binding affinity with CYP3A4 due to the order of the Ka1 and Ka2 values ranging from 104 to 105  L·mol-1 . In addition, astilbin had the highest affinity with CYP3A4, then isoastilbin and neoastilbin, at the three experimental temperatures. Multispectral analysis confirmed that binding of the three flavonoids resulted in clear changes in the secondary structure of CYP3A4. It was found from fluorescence, UV/vis and molecular docking analyses that these three flavonoids strongly bound to CYP3A4 by means of hydrogen bonds and van der Waals forces. The key amino acids around the binding site were also elucidated. Furthermore, the stabilities of the three CYP3A4 complexes were evaluated using molecular dynamics simulation.

Targeting pyroptosis as a preventive and therapeutic approach for stroke

Stroke has caused tremendous social stress worldwide, yet despite decades of research and development of new stroke drugs, most have failed and rt-PA (Recombinant tissue plasminogen activator) is still the accepted treatment for ischemic stroke. the complexity of the stroke mechanism has led to unsatisfactory efficacy of most drugs in clinical trials, indicating that there are still many gaps in our understanding of stroke. Pyroptosis is a programmed cell death (PCD) with inflammatory properties and are thought to be closely associated with stroke. Pyroptosis is regulated by the GSDMD of the gasdermin family, which when cleaved by Caspase-1/Caspase-11 into N-GSDMD with pore-forming activity can bind to the plasma membrane to form small 10-20 nm pores, which would allow the release of inflammatory factors IL-18 and IL-1β before cell rupture, greatly exacerbating the inflammatory response. The pyroptosis occurs mainly in the border zone of cerebral infarction, and glial cells, neuronal cells and brain microvascular endothelial cells (BMECs) all undergo pyroptosis after stroke, which largely exacerbates the breakdown of the blood-brain barrier (BBB) and thus aggravates brain injury. Therefore, pyroptosis may be a good direction for the treatment of stroke. In this review, we focus on the latest mechanisms of action of pyroptosis and the process by which pyroptosis regulates stroke development. We also suggest potential therapeutic stroke drugs that target the pyroptosis pathway, providing additional therapeutic strategies for the clinical management of stroke. The role of pyroptosis after stroke. After stroke, microglia first rush to the damaged area and polarize into M1 and M2 types. Under the influence of various stimuli, microglia undergo pyroptosis, release pro-inflammatory factors, and are converted to the M1 type; astrocytes and neuronal cells also undergo pyroptosis under the stimulation of various pro-inflammatory factors, leading to astrocyte death due to increased osmotic pressure in the membrane, resulting in water absorption and swelling until rupture. BMECs, the main structural component of the BBB, also undergo pyroptosis when stimulated by pro-inflammatory factors released from microglia and astrocytes, leading to the destruction of the structural integrity of the BBB, ultimately causing more severe brain damage. In addition, GSDMD in neutrophils mainly mediate the release of NETs rather than pyroptosis, which also aggravates brain injury. IL-10=interleukin-10; TGF-β = transforming growth factor-β; IL-18=interleukin-18; IL-1β = interleukin-1β; TNF-α = tumor necrosis factor-α; iNOS=induced nitrogen monoxide synthase; MMPs=Matrix metalloproteinases; GSDMD = gasdermin D; BMECs=brain microvascular endothelial cells; BBB = blood-brain barrier.

Astilbin Attenuates Cadmium-Induced Adipose Tissue Damage by Inhibiting NF-κB Pathways and Regulating the Expression of HSPs in Chicken

Cadmium (Cd) can damage tissues by inducing oxidative stress, lymphocyte infiltration, and inflammation in these sites. Meanwhile, astilbin (Ast) is an antioxidant agent. At present, only a few mechanisms of Cd-induced adipose tissue damage have been described. Herein, we assessed the potential protective effects and the molecular mechanism underlying the antioxidant properly of Ast after Cd intake in chicken adipose tissue. In this study, a total of 160 7-day-old roosters were randomly divided into four groups. Roosters were fed with a basic diet (C group), Ast 40 mg/kg (Ast group), CdCl₂ 150 mg/kg + Ast 40 mg/kg (Cd/Ast group), and CdCl₂ 150 mg/kg (Cd group) for 60 days. We found that Cd intake changed the morphology and structure of adipose tissues and decreased the expression of several antioxidants, including total superoxide dismutase (T-SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and total antioxidant capacity (T-AOC), but increased those of oxidative stress markers including malondialdehyde (MDA), inducible nitric oxide synthase (iNOS), NO, and H2O2. Cd further activated the nuclear factor kappa B (NF-κB) signaling pathway and increased the expression of the inflammation-related mediators, interleukin 1beta (IL-1β), interleukin 6 (IL-6), interleukin 8 (IL-8), interleukin 10 (IL-10), cyclooxygenase-2 (COX-2), iNOS, prostaglandin E synthase (PTGES), tumor necrosis factor-alpha (TNF-α), and interferon-gamma (IFN-γ). Cd-induced oxidative stress upregulated the expression of three heat shock proteins (HSPs), including HSP27, HSP70, and HSP90. Summarily, Cd causes oxidative stress-mediated tissue damage by activating the NF-κB pathway, promoting inflammation and upregulating the expression of HSPs. However, Ast supplementation modulates oxidative stress in adipose tissue by inhibiting inflammation mediated by the NF-κB pathway and regulating the expression of HSPs.

Anti-apoptosis effect of traditional Chinese medicine in the treatment of cerebral ischemia-reperfusion injury

Cerebral ischemia, one of the leading causes of neurological dysfunction of brain cells, muscle dysfunction, and death, brings great harm and challenges to individual health, families, and society. Blood flow disruption causes decreased glucose and oxygen, insufficient to maintain normal brain tissue metabolism, resulting in intracellular calcium overload, oxidative stress, neurotoxicity of excitatory amino acids, and inflammation, ultimately leading to neuronal cell necrosis, apoptosis, or neurological abnormalities. This paper summarizes the specific mechanism of cell injury that apoptosis triggered by reperfusion after cerebral ischemia, the related proteins involved in apoptosis, and the experimental progress of herbal medicine treatment through searching, analyzing, and summarizing the PubMed and Web Of Science databases, which includes active ingredients of herbal medicine, prescriptions, Chinese patent medicines, and herbal extracts, providing a new target or new strategy for drug treatment, and providing a reference for future experimental directions and using them to develop suitable small molecule drugs for clinical application. With the research of anti-apoptosis as the core, it is important to find highly effective, low toxicity, safe and cheap compounds from natural plants and animals with abundant resources to prevent and treat Cerebral ischemia/reperfusion (I/R) injury (CIR) and solve human suffering. In addition, understanding and summarizing the apoptotic mechanism of cerebral ischemia-reperfusion injury, the microscopic mechanism of CIR treatment, and the cellular pathways involved will help to develop new drugs.

Anti-Inflammatory Effects of Flavonoids in Common Neurological Disorders Associated with Aging

Aging reduces homeostasis and contributes to increasing the risk of brain diseases and death. Some of the principal characteristics are chronic and low-grade inflammation, a general increase in the secretion of proinflammatory cytokines, and inflammatory markers. Aging-related diseases include focal ischemic stroke and neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). Flavonoids are the most common class of polyphenols and are abundantly found in plant-based foods and beverages. A small group of individual flavonoid molecules (e.g., quercetin, epigallocatechin-3-gallate, and myricetin) has been used to explore the anti-inflammatory effect in vitro studies and in animal models of focal ischemic stroke and AD and PD, and the results show that these molecules reduce the activated neuroglia and several proinflammatory cytokines, and also, inactivate inflammation and inflammasome-related transcription factors. However, the evidence from human studies has been limited. In this review article, we highlight the evidence that individual natural molecules can modulate neuroinflammation in diverse studies from in vitro to animal models to clinical studies of focal ischemic stroke and AD and PD, and we discuss future areas of research that can help researchers to develop new therapeutic agents.

Naringenin attenuates cerebral ischemia/reperfusion injury by inhibiting oxidative stress and inflammatory response via the activation of SIRT1/FOXO1 signaling pathway in vitro

PURPOSE

To explore the protection of naringenin against oxygen-glucose deprivation/reperfusion (OGD/R)-induced HT22 cell injury, a cell model of cerebral ischemia/reperfusion (I/R) injury in vitro, focusing on SIRT1/FOXO1 signaling pathway.

METHODS

Cytotoxicity, apoptosis, reactive oxygen species (ROS) generation, malondialdehyde (MDA) content, 4-hydroxynonenoic acid (4-HNE) level, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) activities were measured by commercial kits. Inflammatory cytokines levels were determined by enzyme-linked immunosorbent assay (ELISA). The protein expressions were monitored by Western blot analysis.

RESULTS

Naringenin significantly ameliorated OGD/R-induced cytotoxicity and apoptosis in HT22 cells. Meanwhile, naringenin promoted SIRT1 and FOXO1 protein expressions in OGD/R-subjected HT22 cells. In addition, naringenin attenuated OGD/R-induced cytotoxicity, apoptosis, oxidative stress (the increased ROS, MDA and 4-HNE levels, and the decreased SOD, GSH-Px and CAT activities) and inflammatory response (the increased tumor necrosis factor-α, interleukin [IL]-1β, and IL-6 levels and the decreased IL-10 level), which were blocked by the inhibition of the SIRT1/FOXO1 signaling pathway induced by SIRT1-siRNA transfection.

CONCLUSIONS

Naringenin protected HT22 cells against OGD/R injury depending on its antioxidant and anti-inflammatory activities via promoting the SIRT1/FOXO1 signaling pathway.

Neuroprotective Effect and Possible Mechanisms of Ginsenoside-Rd for Cerebral Ischemia/Reperfusion Damage in Experimental Animal: A Meta-Analysis and Systematic Review

Ischemic stroke, the most common type of stroke, can lead to a long-term disability with the limitation of effective therapeutic approaches. Ginsenoside-Rd (G-Rd) has been found as a neuroprotective agent. In order to investigate and discuss the neuroprotective function and underlying mechanism of G-Rd in experimental animal models following cerebral ischemic/reperfusion (I/R) injury, PubMed, Embase, SinoMed, and China National Knowledge Infrastructure were searched from their inception dates to May 2022, with no language restriction. Studies that G-Rd was used to treat cerebral I/R damage in vivo were selected. A total of 18 articles were included in this paper, and it was showed that after cerebral I/R damage, G-Rd administration could significantly attenuate infarct volume (19 studies, SMD = −1.75 [−2.21 to − 1.30], P < 0.00001). Subgroup analysis concluded that G-Rd at the moderate doses of >10- <50 mg/kg reduced the infarct volume to the greatest extent, and increasing the dose beyond 50 mg/kg did not produce better results. The neuroprotective effect of G-Rd was not affected by other factors, such as the animal species, the order of administration, and the ischemia time. In comparison with the control group, G-Rd administration could improve neurological recovery (lower score means better recovery: 14 studies, SMD = −1.50 [−2.00 to − 1.00], P < 0.00001; higher score means better recovery: 8 studies, SMD = 1.57 [0.93 to 2.21], P < 0.00001). In addition, this review suggested that G-Rd in vivo can antagonize the reduced oxidative stress, regulate Ca²⁺, and inhibit inflammatory, resistance to apoptosis, and antipyroptosis on cerebral I/R damage. Collectively, G-Rd is a promising natural neuroprotective agent on cerebral I/R injury with unique advantages and a clear mechanism of action. More clinical randomized, blind-controlled trials are also needed to confirm the neuroprotective effect of G-Rd on cerebral I/R injury.

Anfibatide alleviates inflammation and apoptosis via inhibiting NF-kappaB/NLRP3 axis in ischemic stroke

Recent evidence suggests that Nod-like receptor protein-3 (NLRP3) inflammasome is a key mediator of inflammatory response and can induce the activation of apoptosis signaling pathways in ischemic stroke. In this research, we assessed the effects of anfibatide (ANF) on inflammatory and apoptosis in cerebral ischemic injury and the potential mechanisms. Middle cerebral artery occlusion (MCAO) model was established on male Sprague-Dawley rats to induce cerebral ischemia/reperfusion (I/R) injury in vivo. Primary cortical neurons (PCN) cells were exposed to oxygen-glucose deprivation and reintroduction (OGD/R) to mimic cerebral I/R injury in vitro. The results showed that ANF markedly alleviated infarct volume, neurological deficit and neurobehavioral impairment in MCAO/R rats, enhanced cell viability and decreased LDH release in PCN after OGD/R. The number of TUNEL-positive cells, Bax, cleaved-caspase-3, p-IκBα, p-p65, NLRP3, ASC, cleaved caspase-1, IL-β and IL-18 proteins expression were significantly upregulated in the cortex of MCAO/R rats and PCN exposed to OGD/R, NLRP3 and caspase-1 mRNA levels were also evidently elevated. Bcl-2 protein expression significantly decreased in the cortex of MCAO/R rats. Treatment with ANF obviously inhibited the expression of p-IκBα, p-p65, NLRP3, ASC, cleaved caspase-1, Bax and cleaved-caspase-3, promoted the expression of Bcl-2, then decreased the TUNEL-positive cell number and the level of inflammatory cytokines (IL-β and IL-18) in cerebral ischemia reperfusion in vito and in vitro. Our findings suggest that ANF exerts effects of alleviating inflammation and apoptosis through inhibiting NF-kappaB/NLRP3 axis. ANF is a potential candidate for treating cerebral I/R injury.

Quantification of biomarkers and evaluation of antioxidant, anti-inflammatory, and cytotoxicity properties of Dodonaea viscosa grown in Saudi Arabia using HPTLC technique

Dodonaea viscosa (Sapindaceae) was collected from Riyadh, Saudi Arabia. For the simultaneous measurement of quercetin and kaempferol, a validated high-performance thin-layer chromatography (HPTLC) approach was devised in D. viscosa leaf extract. The antioxidant activity was evaluated using diphenyl 1-picrylhydrazyl (DPPH) and 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays. Moreover, the cytotoxic effect was tested against three cancer cell lines A549, HepG2, and MDA-MB-231. The potential anti-inflammatory properties of different fractions of D. viscosa were also evaluated using lipopolysaccharide (LPS)-induced THP-1 macrophages cells. The test samples include a crude extract of leaves and its solvent-soluble fractions of D. viscosa. The results showed that the crude extract and its fractions exhibited various significant biological activities, the fraction of chloroform demonstrated the highest free radical scavenging activity with IC50 values: 172.2 and 257.7 µg/mL for both DPPH and ABTS tests. Additionally, the chloroform fraction had the greatest cytotoxic activity against MDA-MB-231 (IC50 values: 24.6 ± 0.4 µg/mL). Moreover, the chloroform fraction exhibited the highest downregulation of the LPS-induced expression of TNF-α and IL-6. Quercetin and kaempferol were estimated concurrently in leaves crude extract using a validated technique on an HPTLC plate (10 cm2 × 10 cm2) with a combination of toluene–ethyl acetate–formic acid (5:4:0.2; v/v/v) as the mobile phase and a λ max of 254 nm. The amount of quercetin and kaempferol was found to be 31.8 and 15.01 mg/g of dried leaf extract, respectively. The presence of high levels of quercetin and kaempferol in D. viscosa leaves extract could explain its remarkable antioxidant, cytotoxic, and anti-inflammatory effects. The devolved HPTLC method can be used for routine analysis and standardization of D. viscosa crude plant material, extracts, and/or finished products using quercetin and kaempferol as appropriate markers.

The PI3K/AKT Pathway-The Potential Key Mechanisms of Traditional Chinese Medicine for Stroke

Stroke is associated with a high disability and fatality rate, and adversely affects the quality of life of patients and their families. Traditional Chinese Medicine (TCM) has been used effectively in the treatment of stroke for more than 2000 years in China and surrounding countries and regions, and over the years, this field has gleaned extensive clinical treatment experience. The Phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT) pathway is important for regulation of cell migration, proliferation, differentiation, and apoptosis, and plays a vital role in vascularization and oxidative stress in stroke. Current Western medicine treatment protocols for stroke include mainly pharmacologic or mechanical thrombectomy to restore blood flow. This review collates recent advances in the past 5 years in the TCM treatment of stroke involving the PI3K/AKT pathway. TCM treatment significantly reduces neuronal damage, inhibits cell apoptosis, and delays progression of stroke via various PI3K/AKT-mediated downstream pathways. In the future, TCM can provide new perspectives and directions for exploring the key factors, and effective activators or inhibitors that affect occurrence and progression of stroke, thereby facilitating treatment.

Astilbin Activates the Reactive Oxidative Species/PPARγ Pathway to Suppress Effector CD4+ T Cell Activities via Direct Binding With Cytochrome P450 1B1

Astilbin, as a compound of flavonoids, exerts anti-inflammation, antioxidation, and immune-suppression activities. Decreased activation of NF-κB and p38 MAPK and increased activation of SOCS3 and AMPK have been found in astilbin-treated cells. However, what molecules are docked by astilbin to initiate signaling cascades and result in functional changes remains unknown. In the study, we found that astilbin efficiently suppressed TNF-α production and increased CCR9 and CD36 expression of CD4⁺ T cells. In vivo administration of astilbin repressed the occurrence of type 1 diabetes mellitus in non-obese diabetic mice. The PPARγ/SOCS3, PPARγ/PTEN, and PPARγ/AMPK signaling pathways were substantially activated and played key roles in astilbin-induced downregulation of CD4⁺ T cell functions. Transcriptome sequencing results confirmed the changes of signaling molecules involved in the immune system, inflammatory responses, and indicated variations of multiple enzymes with oxidant or antioxidant activities. Astilbin directly induced cytoplasmic ROS production of CD4⁺ T cells ex vivo, but had no effects on mitochondrial ROS and mitochondrial weight. When cellular ROS was depleted, astilbin-treated CD4⁺ T cells remarkably reversed the expression of TNF-α, IFN-γ, CCR9, CD36, and signaling molecules (PPARγ, PTEN, p-AMPK, and SOCS3). Based on bioinformatics, two P450 enzymes (CYP1B1 and CYP19A1) were selected as candidate receptors for astilbin. CYP1B1 was identified as a real docking protein of astilbin in ROS production by AutoDock Vina software analysis and surface plasmon resonance assay. Collectively, astilbin downregulates effector CD4⁺ T cell activities via the CYP1B1/ROS/PPARγ pathway, which firmly supports its potential use in the treatment of inflammation.

Diosmetin alleviates cerebral ischemia-reperfusion injury through Keap1-mediated Nrf2/ARE signaling pathway activation and NLRP3 inflammasome inhibition

Diosmetin was found to exert protective effect on renal and myocardial ischemia-reperfusion (IR) injury. This study aimed to investigate the role of diosmetin in cerebral IR (CIR) injury. PC12 neurons were exposed to oxygen-glucose deprivation/reoxygenation (OGD/R) to establish CIR injury model in vitro and then incubated with diosmetin, and we found that diosmetin alleviated OGD/R-induced viability inhibition, LDH release, apoptosis, and oxidative stress in PC12 cells. Then our results showed that diosmetin downregulated kelch like ECH-associated protein 1 (Keap1) expression, and upregulated nuclear factor E2-related factor 2 (Nrf2) expression, antioxidant response element (ARE) activity and the mRNA and protein expression of heme oxygenase 1 (HO-1) and NAD(P)H: quinone oxidoreductase 1 (NQO1). Keap1 overexpression or Nrf2 silencing both attenuated the neuroprotective effect of diosmetin on PC12 cells. Moreover, diosmetin inhibited the levels of nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) pyrin domain containing 3 (NLRP3) inflammasome pathway related proteins and inflammatory cytokines interleukin (IL)-1β and IL-18. Additionally, a middle cerebral artery occlusion (MCAO) rat model was established and diosmetin was injected for treatment. Diosmetin alleviated CIR-induced neurological deficits, cerebral infarction, brain edema and histopathological damage, and neuronal apoptosis and oxidative stress in MCAO rats. In conclusion, diosmetin attenuated OGD/R-induced PC12 cell viability inhibition, apoptosis, oxidative stress and inflammation through Keap1-mediated Nrf2/ARE signaling activation and NLRP3 inflammasome inhibition, and alleviated CIR-induced neurological injury in MCAO rat model. Our study may provide a novel therapeutic strategy for CIR injury.

NLRP3 Inflammasome Activation: A Therapeutic Target for Cerebral Ischemia–Reperfusion Injury

Millions of patients are suffering from ischemic stroke, it is urgent to figure out the pathogenesis of cerebral ischemia–reperfusion (I/R) injury in order to find an effective cure. After I/R injury, pro-inflammatory cytokines especially interleukin-1β (IL-1β) upregulates in ischemic brain cells, such as microglia and neuron. To ameliorate the inflammation after cerebral I/R injury, nucleotide-binding oligomerization domain (NOD), leucine-rich repeat (LRR), and pyrin domain-containing protein 3 (NLRP3) inflammasome is well-investigated. NLRP3 inflammasomes are complicated protein complexes that are activated by endogenous and exogenous danger signals to participate in the inflammatory response. The assembly and activation of the NLRP3 inflammasome lead to the caspase-1-dependent release of pro-inflammatory cytokines, such as interleukin (IL)-1β and IL-18. Furthermore, pyroptosis is a pro-inflammatory cell death that occurs in a dependent manner on NLRP3 inflammasomes after cerebral I/R injury. In this review, we summarized the assembly and activation of NLRP3 inflammasome; moreover, we also concluded the pivotal role of NLRP3 inflammasome and inhibitors, targeting the NLRP3 inflammasome in cerebral I/R injury.

Formononetin protects against inflammation associated with cerebral ischemia-reperfusion injury in rats by targeting the JAK2/STAT3 signaling pathway

BACKGROUND

Formononetin is a type of phytoestrogen obtained from the Chinese medical herb Red Clover. It exhibits anti-neoplastic hepatoprotective, and neuroprotective properties. However, the anti-inflammatory effect of formononetin in cerebral ischemia-reperfusion injury has not been reported.

OBJECTIVE

To explore the potential mechanism of action of formononetin in cerebral ischemia-reperfusion injury with regard to the JAK2/STAT3 signaling pathway.

METHODS

Male SD rats were used to establish a middle cerebral artery occlusion (MCAO) model and randomly divided into 5 groups: Sham, MCAO, JAK2 Inhibitor (Ag490), Formononetin, Inhibitor + Formononetin. The protective effect of formononetin in MCAO rats was detected by performing neurological deficit testing, TTC staining, H&E staining, Nissl staining, ELISA, RT-PCR, western blotting and immunofluorescence.

RESULTS

Formononetin significantly alleviated the neurological deficit and the pathological state of brain tissues, and reduced the volume of cerebral infarction, levels of IL-18 and TNF-α inflammatory factors in plasma, mRNA levels of IL-6 and IL-1β in rat brain tissue, and the protein levels of p-JAK2, p-STAT3, NLRP3, ASC, cl-Caspase-1, and cl-IL-1β in the MCAO rat brain tissue.

CONCLUSION

Formononetin has anti-inflammatory effects. It may inhibit the relevant targets in the JAK2/STAT3 signaling pathway, thereby having a certain protective effect against cerebral ischemia-reperfusion injury.

Astilbin ameliorates depressive-like behavior caused by postnatal immune activation through Menin-regulated astrocyte inflammation

Postnatal immune activation (PIA) can affect normal brain development and increase the risk of behavioral abnormalities in later life, including depressive-like behavior. Therefore, there is an urgent need to find safe and effective clinical medications for PIA. Recently, the protective effect of astilbin (ASB) in nervous system diseases has attracted much attention. However, the effect of ASB on neurodevelopmental diseases remains unclear. In this study, we used a lipopolysaccharide (LPS)-induced PIA mouse model and found that ASB specifically improved PIA-induced depressive-like behavior but not anxiety-like behavior in adult mice. Astrocytes play an essential role in regulating neuroinflammation, and are the most abundant cell type in the brain. In the PIA model, we found that ASB selectively inhibited astrocyte activation but not microglial activation in the cortex and hippocampus. Moreover, our results showed that ASB specifically upregulated the expression of menin protein in astrocytes and blocked the entry of P65 protein into the nucleus, thus inhibiting the secretion of IL-1β and TNF-α by astrocytes. Taken together, ASB reduced the occurrence of astrocyte-mediated neuroinflammation by targeting menin, thereby attenuating the PIA-induced depressive-like behavior. Our results reveal that ASB may be an attractive antidepressant drug and exert an antidepressant effect in PIA. In terms of drug selection, ASB may be a specific drug for patients with depressive symptoms.

The Influence of Mitochondrial-DNA-Driven Inflammation Pathways on Macrophage Polarization: A New Perspective for Targeted Immunometabolic Therapy in Cerebral Ischemia-Reperfusion Injury

Cerebral ischemia-reperfusion injury is related to inflammation driven by free mitochondrial DNA. At the same time, the pro-inflammatory activation of macrophages, that is, polarization in the M1 direction, aggravates the cycle of inflammatory damage. They promote each other and eventually transform macrophages/microglia into neurotoxic macrophages by improving macrophage glycolysis, transforming arginine metabolism, and controlling fatty acid synthesis. Therefore, we propose targeting the mtDNA-driven inflammatory response while controlling the metabolic state of macrophages in brain tissue to reduce the possibility of cerebral ischemia-reperfusion injury.

Protective Effect of Xiao-Xu-Ming Decoction-Mediated Inhibition of ROS/NLRP3 Axis on Lipopolysaccharide-Induced Acute Lung Injury In Vitro and In Vivo

Background

As a traditional Chinese medicine prescription, Xiao-Xu-Ming decoction (XXMD) could reduce the incidence of lung infection of patients with cerebral infarction. Nonetheless, the therapeutic mechanisms of XXMD in acute lung injury (ALI) remain to be elucidated. Our study was aimed to assess the effects of XXMD protects against ALI.

Methods

ALI model was induced by intraperitoneal injection of lipopolysaccharide (LPS) in vivo. In vitro, human pulmonary alveolar epithelial cells (HPAEpiC) were treated with XXMD and were followed by LPS treatment. The levels of ZO-1, CLDN4, NLRP3, and caspase 1 were detected by Western blot, and the content of IL-1 and IL-18 was determined by ELISA. Transepithelial electrical resistance was used to detect the cell permeability. The reactive oxygen species (ROS) levels within the cells were evaluated by flow cytometry.

Results

Our results showed that XXMD attenuated LPS-induced oxidative stress, barrier dysfunction, and the activation of NLRP3 inflammasome in vitro, as evidenced by enhanced ROS production, TEER levels, expression of NLRP3 and caspase 1 (p20) and release of IL-1β and IL-18, and weakened cell permeability. In addition, XXMD could counteract the effects of NLRP3 overexpression on HPAEpiC and vice versa. XXMD treatment also ameliorated the degree of neutrophil infiltration, barrier dysfunction, and the activation of NLRP3 in LPS-induced ALI lung tissues in vivo.

Conclusion

The findings showed that XXMD could alleviate LPS-induced ALI injury and inhibit inflammation and suppress ROS/NLRP3 signaling pathway, which were involved in these protective effects.

Guhong Injection Alleviates Cerebral Ischemia-Reperfusion Injury via the PKC/HIF-1α Pathway in Rats

Guhong injection (GHI) is a drug for ischemic stroke created by combining safflower, a traditional Chinese medicine, and aceglutamide, a Western medicine. In this study, we investigated the curative effect of GHI on cerebral ischemia–reperfusion (I/R) injury via the PKC/HIF-1α pathway in rats. Adult male Sprague Dawley rats were randomly divided into seven groups: sham-operated, middle cerebral artery occlusion (MCAO), GHI, nimodipine injection (NMDP), MCAO + LY317615 (PKC inhibitor), GHI + LY317615, and NMDP + LY317615. After establishing an MCAO rat model, we performed neurological deficit testing, 2,3,5-triphenyltetrazolium chloride staining, hematoxylin and eosin (HE) staining, enzyme-linked immunosorbent assay, Western blotting, and q-PCR to detect the brain damage in rats. Compared with the MCAO group, the GHI and GHI + LY317615 group showed neurological damage amelioration as well as decreases in serum hypoxia-inducible factor-1α (HIF-1α), protein kinase C (PKC), and erythropoietin levels; brain HIF-1α and inducible nitric oxide synthase protein expression; and brain HIF-1α and NOX-4 mRNA expression. These effects were similar to those in the positive control groups NMDP and NMDP + LY317615. Thus, our results confirmed GHI can ameliorate cerebral I/R injury in MCAO rats possibly via the PKC/HIF-1α pathway.

Natural products attenuate PI3K/Akt/mTOR signaling pathway: A promising strategy in regulating neurodegeneration

BACKGROUND

As common, progressive, and chronic causes of disability and death, neurodegenerative diseases (NDDs) significantly threaten human health, while no effective treatment is available. Given the engagement of multiple dysregulated pathways in neurodegeneration, there is an imperative need to target the axis and provide effective/multi-target agents to tackle neurodegeneration. Recent studies have revealed the role of phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) in some diseases and natural products with therapeutic potentials.

PURPOSE

This is the first systematic and comprehensive review on the role of plant-derived secondary metabolites in managing and/or treating various neuronal disorders via the PI3K/Akt/mTOR signaling pathway.

STUDY DESIGN AND METHODS

A systematic and comprehensive review was done based on the PubMed, Scopus, Web of Science, and Cochrane electronic databases. Two independent investigators followed the PRISMA guidelines and included papers on PI3K/Akt/mTOR and interconnected pathways/mediators targeted by phytochemicals in NDDs.

RESULTS

Natural products are multi-target agents with diverse pharmacological and biological activities and rich sources for discovering and developing novel therapeutic agents. Accordingly, recent studies have shown increasing phytochemicals in combating Alzheimer's disease, aging, Parkinson's disease, brain/spinal cord damages, depression, and other neuronal-associated dysfunctions. Amongst the emerging targets in neurodegeneration, PI3K/Akt/mTOR is of great importance. Therefore, attenuation of these mediators would be a great step towards neuroprotection in such NDDs.

CONCLUSION

The application of plant-derived secondary metabolites in managing and/or treating various neuronal disorders through the PI3K/Akt/mTOR signaling pathway is a promising strategy towards neuroprotection.

Uncoupling Protein 2 Deficiency Enhances NLRP3 Inflammasome Activation Following Hyperglycemia-Induced Exacerbation of Cerebral Ischemia and Reperfusion Damage In Vitro and In Vivo

Mitochondrial uncoupling protein 2 (UCP2) deficiency exacerbates brain damage following cerebral ischemia/reperfusion (I/R). The Nod-like receptor protein-3 (NLRP3) inflammasome also plays a vital role in cerebral I/R damage. However, the effect of UCP2 on NLRP3 inflammasome-mediated hyperglycemia and I/R damage is not clear. In the present study, UCP2-knockout (UCP2-/-) and wild-type (WT) mice were used to establish a model of middle cerebral artery occlusion (MCAO) and reperfusion under normo- and hyperglycemic conditions. HT22 cells were established as a model of oxygen-glucose deprivation and reoxygenation (OGD/R) with high glucose to mimic hyperglycemia and I/R in vitro. HT22 cells were treated with/without different concentrations of the UCP2-specific inhibitor genipin for different periods of time. The results showed that UCP2 deficiency significantly increased histopathological changes and apoptosis after cerebral I/R damage in hyperglycemic mice. Moreover, UCP2 deficiency enhanced NLRP3 inflammasome activation in neurons when cerebral I/R damage was exacerbated by hyperglycemia. Furthermore, UCP2 deficiency enhanced NLRP3 inflammasome activation and reactive oxygen species (ROS) production in HT22 cells under OGD/R and high-glucose conditions. UCP2 deficiency aggravated hyperglycemia-induced exacerbation of cerebral I/R damage. UCP2 deficiency also enhanced NLRP3 inflammasome activation and ROS production in neurons in vitro and in vivo. These findings suggest that UCP2 deficiency enhances NLRP3 inflammasome activation following hyperglycemia-induced exacerbation of cerebral I/R damage in vitro and in vivo. UCP2 may be a potential therapeutic target for hyperglycemia-induced exacerbation of cerebral I/R damage.

Oxymatrine improves blood-brain barrier integrity after cerebral ischemia-reperfusion injury by downregulating CAV1 and MMP9 expression

BACKGROUND

Ischemic stroke (IS) is a major neurological condition associated with extremely high morbidity and mortality worldwide. Oxymatrine (OMT), a quinolizidine alkaloid extracted from the root of Sophora flavescens, has neuroprotective properties and protects against IS. However, whether its protective effect involves alterations in the integrity of the blood-brain barrier (BBB) is unknown.

PURPOSE

Here, we used in vivo and in vitro models of IS to evaluate the protective effects of OMT and to establish whether its effects are mediated via the modulation of the BBB function.

METHODS

We assessed the effects of OMT by using neurological function scores, triphenyltetrazolium chloride staining, Nissl staining, and terminal deoxynucleotidyl transferase dUTP nick end labeling.

RESULTS

OMT significantly prevented cellular damage, improved neurological function, and reduced BBB permeability in a mouse model of cerebral ischemia-reperfusion. Additionally, OMT protected the function of the tight junctions of bEend.3 cells against the consequences of oxygen-glucose deprivation. Furthermore, intracranial lentivirus injection of short hairpin RNA targeting Cav1 decreased caveolin-1 expression and inhibited the neuroprotective effects of OMT.

CONCLUSIONS

OMT attenuated ischemia-reperfusion injury-induced damage to the BBB, and this neuroprotective action was at least partially dependent on the expression levels of CAV1 and MMP9 proteins. Therefore, OMT may offer effective protection against BBB injury induced by ischemia-reperfusion episodes.

Chromone Derivatives CM3a Potently Eradicate Staphylococcus aureus Biofilms by Inhibiting Cell Adherence

Introduction

The ability of Staphylococcus aureus to form biofilms is associated with high mortality and treatment costs. Established biofilms cannot be eradicated by many conventional antibiotics due to the development of antibiotic tolerance by S. aureus. Here we report the synthesis and biological characterization of novel small-molecule compounds with antibiofilm activity. Chromone 5-maleimide substitution compounds (CM3a) showed favorable antibacterial activity against S. aureus.

Methods

CM3A with antibacterial activity was synthesized and screened. The minimum inhibitory concentration (MIC) of CM3a were determined by the broth microdilution method. Biofilm eradication assay and colony count methods were used to investigate the effect of CM3a on S. aureus biofilm disruption and killing. Changes in biofilm architecture when subjected to CM3a, were visualized using confocal laser scanning microscopy (CLSM). CCK-8 assay and survival rate of Galleria mellonella larvae were used to test the toxicity of CM3a.

Results

The minimum inhibitory concentration (MIC) of CM3a against S. aureus was about 26.4 μM. Biofilm staining and laser scanning confocal microscopy analysis showed that CM3a eradicated S. aureus biofilms by reducing the viability of the constituent bacterial cells. On the other hand, CM3a showed negligible toxicity against mouse alveolar epithelial cells and Galleria mellonella larvae.

Conclusion

Chromone derivatives CM3a has therapeutic potential as a safe and effective compound for the treatment of S. aureus infection.