NRF2/HO-1 activation via ERK pathway involved in the anti-neuroinflammatory effect of Astragaloside IV in LPS induced microglial cells

Silencing of secreted phosphoprotein 1 attenuates sciatic nerve injury-induced neuropathic pain: Regulating extracellular signal-regulated kinase and neuroinflammatory signaling pathways

BACKGROUND

Neuropathic pain (NP) is a chronic pathological pain that affects the quality of life and is a huge medical burden for affected patients. In this study, we aimed to explore the effects of secreted phosphoprotein 1 (SPP1) on NP.

METHODS

We established a chronic constriction injury (CCI) rat model, knocked down SPP1 via an intrathecal injection, and/or activated the extracellular signal-regulated kinase (ERK) pathway with insulin-like growth factor 1 (IGF-1) treatment. Pain behaviors, including paw withdrawal threshold (PWT), paw withdrawal latency (PWL), lifting number, and frequency, were assessed. After sacrificing rats, the L4-L5 dorsal root ganglion was collected. Then, SPP1 levels were determined using quantitative polymerase chain reaction (qPCR) and western blot analysis. The levels of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-6, IL-10, epidermal growth factor (EGF), vascular endothelial growth factor (VEGF), and transforming growth factor (TGF)-β were determined using qPCR and enzyme-linked immunosorbent assay. The levels of ERK pathway factors were determined via western blot analysis.

RESULTS

We found that CCI decreased PWT and PWL, increased the lifting number and frequency, and upregulated SPP1 levels. The loss of SPP1 reversed these CCI-induced effects. Additionally, CCI upregulated IL-1β, TNF-α, IL-6, EGF, and VEGF levels, downregulated TGF-β levels, and activated the ERK pathway, while silencing of SPP1 abrogated these CCI-induced effects. Moreover, IGF-1 treatment reversed the effects of SPP1 loss.

CONCLUSIONS

The data indicate that silencing SPP1 attenuates NP via inactivation of the ERK pathway, suggesting that SPP1 may be a promising target for NP treatment.

Exploring Chinese herbal medicine for ischemic stroke: insights into microglia and signaling pathways

Ischemic stroke is a prevalent clinical condition affecting the central nervous system, characterized by a high mortality and disability rate. Its incidence is progressively rising, particularly among younger individuals, posing a significant threat to human well-being. The activation and polarization of microglia, leading to pro-inflammatory and anti-inflammatory responses, are widely recognized as pivotal factors in the pathogenesis of cerebral ischemia and reperfusion injury. Traditional Chinese herbal medicines (TCHMs) boasts a rich historical background, notable efficacy, and minimal adverse effects. It exerts its effects by modulating microglia activation and polarization, suppressing inflammatory responses, and ameliorating nerve injury through the mediation of microglia and various associated pathways (such as NF-κB signaling pathway, Toll-like signaling pathway, Notch signaling pathway, AMPK signaling pathway, MAPK signaling pathway, among others). Consequently, this article focuses on microglia as a therapeutic target, reviewing relevant pathway of literature on TCHMs to mitigate neuroinflammation and mediate IS injury, while also exploring research on drug delivery of TCHMs. The ultimate goal is to provide new insights that can contribute to the clinical management of IS using TCHMs.

Role of Natural Compounds Modulating Heme Catabolic Pathway in Gut, Liver, Cardiovascular, and Brain Diseases

The crucial physiological process of heme breakdown yields biliverdin (BV) and bilirubin (BR) as byproducts. BV, BR, and the enzymes involved in their production (the "yellow players-YP") are increasingly documented as endogenous modulators of human health. Mildly elevated serum bilirubin concentration has been correlated with a reduced risk of multiple chronic pro-oxidant and pro-inflammatory diseases, especially in the elderly. BR and BV per se have been demonstrated to protect against neurodegenerative diseases, in which heme oxygenase (HMOX), the main enzyme in the production of pigments, is almost always altered. HMOX upregulation has been interpreted as a tentative defense against the ongoing pathologic mechanisms. With the demonstration that multiple cells possess YP, their propensity to be modulated, and their broad spectrum of activity on multiple signaling pathways, the YP have assumed the role of an adjustable system that can promote health in adults. Based on that, there is an ongoing effort to induce their activity as a therapeutic option, and natural compounds are an attractive alternative to the goal, possibly requiring only minimal changes in the life style. We review the most recent evidence of the potential of natural compounds in targeting the YP in the context of the most common pathologic condition of adult and elderly life.

Regulatory mechanisms of natural compounds from traditional Chinese herbal medicines on the microglial response in ischemic stroke

BACKGROUND

Development of clinically effective neuroprotective agents for stroke therapy is still a challenging task. Microglia play a critical role in brain injury and recovery after ischemic stroke. Traditional Chinese herbal medicines (TCHMs) are based on a unique therapeutic principle, have various formulas, and have long been widely used to treat stroke. Therefore, the active compounds in TCHMs and their underlying mechanisms of action are attracting increasing attention in the field of stroke drug development.

PURPOSE

To summarize the regulatory mechanisms of TCHM-derived natural compounds on the microglial response in animal models of ischemic stroke.

METHODS

We searched studies published until 10 April 2023 in the Web of Science, PubMed, and ScienceDirect using the following keywords: natural compounds, natural products or phytochemicals, traditional Chinese Medicine or Chinese herbal medicine, microglia, and ischemic stroke. This review was prepared according to PRISMA (Preferred Reporting Item for Systematic Reviews and Meta-Analysis) guidelines.

RESULTS

Natural compounds derived from TCHMs can attenuate the M1 phenotype of microglia, which is involved in the detrimental inflammatory response, via inhibition of NF-κB, MAPKs, JAK/STAT, Notch, TLR4, P2X7R, CX3CR1, IL-17RA, the NLRP3 inflammasome, and pro-oxidant enzymes. Additionally, the neuroprotective response of microglia with the M2 phenotype can be enhanced by activating Nrf2/HO-1, PI3K/AKT, AMPK, PPARγ, SIRT1, CB2R, TREM2, nAChR, and IL-33/ST2. Several clinical trials showed that TCHM-derived natural compounds that regulate microglial responses have significant and safe therapeutic effects, but further well-designed clinical studies are needed.

CONCLUSIONS

Further research regarding the direct targets and potential pleiotropic or synergistic effects of natural compounds would provide a more reasonable approach for regulation of the microglial response with the possibility of successful stroke drug development.

Ergosterol Isolated from Antrodia camphorata Suppresses LPS-Induced Neuroinflammatory Responses in Microglia Cells and ICR Mice

Inflammation caused by microglial activation is important in neurodegenerative diseases. In this research, we tried to identify safe and effective anti-neuroinflammatory agents by screening a natural compounds library and found that Ergosterol can inhibit the nuclear factor kappa-light-chain enhancer of the activated B cells (NF-κB) pathway induced by lipopolysaccharide (LPS) in microglia cells. Ergosterol has been reported to be an effective anti-inflammatory agent. Nevertheless, the potential regulatory role of Ergosterol in neuroinflammatory responses has not been fully investigated. We further investigated the mechanism of Ergosterol that regulates LPS-induced microglial activation and neuroinflammatory reactions both in vitro and in vivo. The results showed that Ergosterol can significantly decrease the pro-inflammatory cytokines induced by LPS in BV2 and HMC3 microglial cells, possibly by inhibiting the NF-κB, protein kinase B (AKT), and mitogen-activated protein kinase (MAPK) signaling pathways. In addition, we treated Institute of Cancer Research (ICR) mice with a safe concentration of Ergosterol following LPS injection. Ergosterol treatment significantly decreased microglial activation-associated ionized calcium-binding adapter molecule-1 (IBA-1), NF-κB phosphorylation, and pro-inflammatory cytokine levels. Moreover, Ergosterol pretreatment clearly reduced LPS-induced neuron damage by restoring the expression of synaptic proteins. Our data may provide insight into possible therapeutic strategies for neuroinflammatory disorders.

Total astragalosides decrease apoptosis and pyroptosis by inhibiting enterovirus 71 replication in gastric epithelial cells

Enterovirus 71 (EV71) is one of the primary pathogens involved in severe hand, foot and mouth disease in children. EV71 infection causes various types of programmed cell death. However, there are currently no clinically approved specific antiviral drugs for control of EV71 infection. Astragalus membranaceus (AM), a Traditional Chinese medicine, has been used in antiviral therapy in China. The aim of the present study was to determine whether total astragalosides (ASTs), bioactive components of AM, protect against EV. DAPI nuclear staining was used to observe morphological changes of the nucleus and the protective effect of ASTs, which revealed that the nucleus shrank following EV71 infection, while ASTs reversed it. Cell Counting Kit-8 assay found that human normal gastric epithelial cell (GES-1 cell) viability decreased following EV71 infection, while lactate dehydrogenase (LDH) assay showed that EV71 infection induced GES-1 cell damage. Western blotting was used to measure the expression levels of apoptosis and pyroptosis marker protein to determine whether EV71 infection induced apoptosis and pyroptosis in GES-1 cells. Reverse transcription-quantitative PCR was used to determine the anti-EV71 effect of ASTs. The results showed that ASTs protected GES-1 cells from EV71-induced cell apoptosis and pyroptosis. Furthermore, the present data demonstrated that the protective effect of ASTs was exerted by suppressing EV71 replication and release. These findings suggested that ASTs may represent a potential antiviral agent for the treatment of EV71 infection.

Potential anti-inflammatory effect of anti-HMGB1 in animal models of ICH by downregulating the TLR4 signaling pathway and regulating the inflammatory cytokines along with increasing HO1 and NRF2

Intracerebral hemorrhage (ICH) is a severe clinical problem without effective treatment; the leading cause is neuroinflammation. High-mobility group box one protein (HMGB1) is an abundant protein in the cell nucleus of most mammalian cells, which exerts its function by binding to chromatin. The present study focused on the therapeutic effect of anti-HMGB1 on ICH via the downregulation of inflammatory pathways. The ICH mice models were created by collagenase IV injection in the striatum of mice. Then, mice were received different medications and divided into three groups: anti-HMGB1, anti-Toll-like receptor 4 (TLR4), and non-treated ICH groups. Cerebrospinal fluid (CSF) was obtained, and ELISA was carried out to determine the levels of inflammatory agents. Microglial cells were isolated from the cerebral hemispheres, and then Real-Time PCR and western blot were performed. The results showed that the anti-inflammatory effects of anti-HMGB1 were tremendous than anti-TLR4. Overall, the results showed that anti-HMGB1 had a more reducer effect on pro-inflammatory cytokines release (****P < 0.0001) and expression (****P < 0.0001) than anti-TLR4 when compared with the control group. It was also determined that anti-HMGB1 increased heme-oxygenase-1 (HO1) and nuclear factor erythroid-derived factor 2-related factor 2 (NRF2) (****P < 0.0001) expression in comparison with the control group while it was not significant for anti-TLR4 (CLI-095). The present study suggested that anti-HMGB1 serves as a potential anti-inflammatory molecule via reducing TLR4-related signaling pathways, pro-inflammatory cytokines production, and increasing the production of the anti-inflammatory cytokine along with heme-oxygenase-1 HO1 and NRF2 increment.

Astragaloside IV Ameliorates Cognitive Impairment and Neuroinflammation in an Oligomeric Aβ Induced Alzheimer's Disease Mouse Model via Inhibition of Microglial Activation and NADPH Oxidase Expression

Microglial activation and neuroinflammation induced by amyloid β (Aβ) play pivotal roles in Alzheimer's disease (AD) pathogenesis. Astragaloside IV (AS-IV) is one of the major active compounds of the traditional Chinese medicine Astmgali Radix. It has been reported that AS-IV could protect against Aβ-induced neuroinflammation and cognitive impairment, but the underlying mechanisms need to be further clarified. In this study, the therapeutic effects of AS-IV were investigated in an oligomeric Aβ (oAβ) induced AD mice model. The effects of AS-IV on microglial activation, neuronal damage and reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase expression were further studied. Different doses of AS-IV were administered intragastrically once a day after intracerebroventricularly oAβ injection. Results of behavioral experiments including novel object recognition (NOR) test and Morris water maze (MWM) test revealed that AS-IV administration could significantly ameliorate oAβ-induced cognitive impairment in a dose dependent manner. Enzyme linked immunosorbent assay (ELISA) results showed that increased levels of reactive oxygen species (ROS), tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β) and IL-6 in hippocampal tissues induced by oAβ injection were remarkably inhibited after AS-IV treatment. OAβ induced microglial activation and neuronal damage was significantly suppressed in AS-IV-treated mice brain, observed in immunohistochemistry results. Furthermore, oAβ upregulated protein expression of NADPH oxidase subunits gp91phox, p47phox, p22phox and p67phox were remarkably reduced by AS-IV in Western blotting assay. These results revealed that AS-IV could ameliorate oAβ-induced cognitive impairment, neuroinflammation and neuronal damage, which were possibly mediated by inhibition of microglial activation and down-regulation of NADPH oxidase protein expression. Our findings provide new insights of AS-IV for the treatment of neuroinflammation related diseases such as AD.

Antioxidative effects of polypyrimidine tract-binding protein-associated splicing factor against pathological retinal angiogenesis through promotion of mitochondrial function

Reactive oxygen species (ROS), a by-product of oxygen metabolism mainly originating from mitochondria, participate in many pathological processes related to ophthalmopathy. Excessive production of ROS leads to oxidative stress, which influences the permeability, proliferation, migration, and tube formation of human retinal microcapillary endothelial cells (HRMECs). The molecular mechanisms underlying the effects of ROS are not clear. In Vldlr-/- mice, we used fundus fluorescein angiography and retinal flat mount staining to observe the effect of polypyrimidine tract-binding protein-associated splicing factor (PSF) on pathological retinal neovascularization in vivo. Additionally, in human retinal microvascular endothelial cells treated with 4-HNE, cell viability, tube formation, wound healing, and Transwell assays were performed to study the effect of PSF on the proliferation, migration, and tube formation of retinal vascular endothelial cells in vitro. Moreover, reactive oxygen species assay, real-time PCR, and Western blot were included to analyze the potential mechanism of PSF in the above series of effects. PSF ameliorated intraretinal neovascularization (IRNV) in vivo in Vldlr-/- mice. Under 4-hydroxynonenal (4-HNE) conditions in vitro, PSF reprogrammed mitochondrial bioenergetic and glycolytic profiles. It also reduced ROS levels and inhibited 4-HNE-induced angiogenesis, which involves the proliferation, migration, and tube formation of HRMECs. These results suggest that PSF participates in the regulation of HRMECs proliferation and migration during the development of pathological angiogenesis. We demonstrated that PSF enhanced Nrf2 activation and heme oxygenase-1 (HO-1) expression via extracellular signal-regulated kinase (ERK) and Akt signaling in HRMECs, which subsequently resulted in intracellular ROS scavenging. PSF restored endoplasmic reticulum (ER) redox homeostasis, which was indicated by an increase in protein disulfide isomerase (PDI) and Ero-1α and a reduction in GRP78 and C/EBP homologous protein (CHOP). PSF also attenuated ER stress via regulation of the protein kinase R (PKR)-like endoplasmic reticulum kinase PERK/eukaryotic translation factor 2 alpha (eIF2α)/activating transcription factor 4 (ATF4) pathway in 4-HNE-treated HRMECs. Our research shows that PSF may be a potential antioxidant that regulates pathological angiogenesis through ERK-AKT/Nrf2/HO-1 and PERK/eIF2α/ATF4 signal regulation. KEY MESSAGES: Reactive oxygen species (ROS) mainly originating from mitochondria is a by-product of oxygen metabolism in the body and participates in the pathological process related to multiple blindness-related ophthalmopathy. Moreover , excessive production of ROS will lead to oxidative stress. Consequently, oxidative stress influences the permeability, proliferation, migration, and tube formation of human retinal microcapillary endothelial cells (HRMECs). The molecular mechanisms underlying the effects of ROS remain unclear. Here, we reveal that Polypyrimidine tract-binding protein-associated splicing factor (PSF) ameliorates intraretinal neovascularization (IRNV) in vivo in Vldlr-/- mice. Furthermore, under 4-HNE conditions in vitro, PSF reprograms mitochondrial bioenergetic and glycolytic profiles, reduces ROS levels, and inhibits 4-HNE-induced angiogenesis, which involves the proliferation, migration, and tube formation of HRMECs, suggesting that it participates in regulating the proliferation and migration of HRMECs during the development of pathological angiogenesis. Furthermore, PSF enhances Nrf2 activation and HO-1 expression through ERK and AKT signaling in HRMECs, resulting in intracellular ROS scavenging. PSF restores endoplasmic reticulum (ER) redox homeostasis, as indicated by an increase in PDI and Ero-1α and a reduction in GRP78 and CHOP. PSF also attenuates ER stress by regulating the PERK/eIF2α/ATF4 pathway in 4-HNE-treated HRMECs.

Exploring the Regulatory Mechanism of Hedysarum Multijugum Maxim.-Chuanxiong Rhizoma Compound on HIF-VEGF Pathway and Cerebral Ischemia-Reperfusion Injury's Biological Network Based on Systematic Pharmacology

Background: Clinical research found that Hedysarum Multijugum Maxim.-Chuanxiong Rhizoma Compound (HCC) has definite curative effect on cerebral ischemic diseases, such as ischemic stroke and cerebral ischemia-reperfusion injury (CIR). However, its mechanism for treating cerebral ischemia is still not fully explained.

Methods: The traditional Chinese medicine related database were utilized to obtain the components of HCC. The Pharmmapper were used to predict HCC’s potential targets. The CIR genes were obtained from Genecards and OMIM and the protein-protein interaction (PPI) data of HCC’s targets and IS genes were obtained from String database. After that, the DAVID platform was applied for Gene Ontology (GO) enrichment analysis and pathway enrichment analysis. Finally, a series of animal experiments were carried out to further explore the mechanism of HCC intervention in CIR.

Results: The prediction results of systematic pharmacology showed that HCC can regulate CIR-related targets (such as AKT1, MAPK1, CASP3, EGFR), biological processes (such as angiogenesis, neuronal axonal injury, blood coagulation, calcium homeostasis) and signaling pathways (such as HIF-1, VEGF, Ras, FoxO signaling). The experiments showed that HCC can improve the neurological deficit score, decrease the volume of cerebral infarction and up-regulate the expression of HIF-1α/VEGF and VEGFR protein and mRNA (p < 0.05).

Conclusion: HCC may play a therapeutic role by regulating CIR-related targets, biological processes and signaling pathways found on this study.

The role of Nrf2 in astragaloside IV-mediated antioxidative protection on heart failure

CONTEXT

Heart failure is one of the most serious diseases worldwide. Astragaloside IV (ASI) is widely used in the treatment of cardiovascular diseases.

OBJECTIVE

To elucidate the antioxidative mechanism of ASI in a rat model of left coronary artery ligation.

MATERIALS AND METHODS

Left coronary artery of Sprague-Dawley rats was ligated to establish the model of heart failure, and then vehicle (saline) or ASI (1 mg/kg/day) was orally administered to the rats (n = 15) for 6 weeks. Echocardiography was used to evaluate the cardiac function. Myocardial infarct size was measured by triphenyltetrazolium chloride staining. Oxidative stress in the ventricular myocardium was determined. Molecular mechanisms were investigated by Western blot and chromatin immunoprecipitation.

RESULTS

ASI improved the cardiac function, especially ejection fraction (75.27 ± 5.75% vs. 36.26 ± 4.14%) and fractional shortening (45.39 ± 3.66% vs. 17.88 ± 1.32%), and reduced the infarct size of left ventricle (20.69 ± 2.98% vs. 39.11 ± 3.97%). ASI maintained the levels of glutathione, catalase and superoxide dismutase and prevented the leakage of creatine kinase. In addition, ASI induced the protein expression of Nrf2 (1.97-fold) and HO-1 (2.79-fold), while reduced that of Keap-1 (0.77-fold) in the ventricular myocardium. In H9c2 cells, a rat cardiomyocyte cell line, ASI induced the translocation of Nrf2 from cytoplasm to nucleus, followed by transcriptional activation of NQO-1 (8.27-fold), SOD-2 (3.27-fold) and Txn-1 (9.83-fold) genes.

DISCUSSION AND CONCLUSIONS

ASI prevented heart failure by counteracting oxidative stress through the Nrf2/HO-1 pathway. Application in clinical practice warrants further investigation.

Short ELF-EMF Exposure Targets SIRT1/Nrf2/HO-1 Signaling in THP-1 Cells

Extremely low frequency electromagnetic fields (ELF-EMFs) have been known to modulate inflammatory responses by targeting signal transduction pathways and influencing cellular redox balance through the generation of oxidants and antioxidants. Here, we studied the molecular mechanism underlying the anti-oxidative effect of ELF-EMF in THP-1 cells, particularly with respect to antioxidant enzymes, such as heme oxygenase-1 (HO-1), regulated transcriptionally through nuclear factor E2-related factor 2 (Nrf2) activation. Cells treated with lipopolysaccharides (LPS) were exposed to a 50 Hz, 1 mT extremely low frequency electromagnetic fields for 1 h, 6 h and, 24 h. Our results indicate that ELF-EMF induced HO-1 mRNA and protein expression in LPS-treated THP-1 cells, with peak expression at 6 h, accompanied with a concomitant migration to the nucleus of a truncated HO-1 protein form. The immunostaining analysis further verified a nuclear enrichment of HO-1. Moreover, ELF-EMF inhibited the protein expressions of the sirtuin1 (SIRT1) and nuclear factor kappa B (NF-kB) pathways, confirming their anti-inflammatory/antioxidative role. Pretreatment with LY294002 (Akt inhibitor) and PD980559 (ERK inhibitor) inhibited LPS-induced Nrf2 nuclear translocation and HO-1 protein expression in ELF-EMF-exposed cells. Taken together, our results suggest that short ELF-EMF exposure exerts a protective role in THP-1 cells treated with an inflammatory/oxidative insult such as LPS, via the regulation of Nrf-2/HO-1 and SIRT1 /NF-kB pathways associated with intracellular glutathione (GSH) accumulation.

Mechanisms of the lipopolysaccharide-induced inflammatory response in alveolar epithelial cell/macrophage co-culture

The interaction between alveolar epithelial cells (EpCs) and macrophages (MPs) serves an important role in initiating and maintaining inflammation in chronic pulmonary diseases. The aim of the present study was to investigate the molecular mechanisms of the inflammatory response in co-cultured EpCs and MPs. Briefly, a co-culture system of A549 (EpCs) and THP-1 (monocyte/MPs) cells was established in a filter-separated Transwell plate to evaluate the inflammatory response. Following lipopolysaccharide (LPS) treatment, cytokine levels were measured using ELISAs, NF-κB transcription factor activity was detected using EMSA and protein expression levels were analyzed using Western blot assays subsequently in EpCs and MPs. Co-cultured EpCs/MPs were found to secrete increased levels of interleukin (IL)-6, IL-1β, IL-8 and tumor necrosis factor (TNF)-α following LPS exposure for 6, 12, 24 and 48 h compared with either EpC or MP monocultures. Concurrently, NF-κB was revealed to be activated in MPs at 6 and 12 h, and in EpCs at 24 h. NF-κB DNA binding, Toll-like receptor 4 expression levels and the p65 phosphorylation status were also increased, which may contribute to the inflammatory response in the EpC/MP co-cultures. Notably, cytokine levels decreased following the inhibition of NF-κB expression with pyrrolidinedithiocarbamate. In conclusion, the present study successfully established an EpC/MP co-culture system using LPS, which may be a useful model for studying chronic inflammation in vitro.

Schisantherin A attenuates sepsis-induced acute kidney injury by suppressing inflammation via regulating the NRF2 pathway

AIMS

Tubulointerstitial inflammation is recognized as a key determinant of progressive sepsis-induced acute kidney injury (AKI). Schisantherin A (SchA) has been shown to be capable of regulating inflammatory processes. In the present study, we explored the possibility of SchA in preventing lipopolysaccharide (LPS)-induced kidney inflammation and injury.

MATERIALS AND METHODS

AKI was induced by a single intraperitoneal injection of LPS in CD1 mice, administration of SchA was used for treatment. The protective effect of SchA on renal function and inflammation were analyzed respectively; the NRK-52E cell line was employed for the in vitro study and relative molecular mechanism was explored.

KEY FINDINGS

Administration with SchA markedly attenuated LPS-induced damage on renal function and histopathological changes of the kidney. Additionally, pretreatment with SchA could inhibit the expression of inflammatory factors in the kidneys. In NRK-52E cells, SchA treatment significantly inhibited LPS-induced NF-κB activation and pro-inflammatory cytokine expression. Moreover, SchA could promote NRF2 pathway activation, and further blockade of NRF2 activation reversed the SchA-induced inhibition of NF-κB activation.

SIGNIFICANCE

These presented results indicated that SchA may have great potential for protecting against sepsis-induced AKI.

Naturally Derived Heme-Oxygenase 1 Inducers and Their Therapeutic Application to Immune-Mediated Diseases

Heme oxygenase (HO) is the primary antioxidant enzyme involved in heme group degradation. A variety of stimuli triggers the expression of the inducible HO-1 isoform, which is modulated by its substrate and cellular stressors. A major anti-inflammatory role has been assigned to the HO-1 activity. Therefore, in recent years HO-1 induction has been employed as an approach to treating several disorders displaying some immune alterations components, such as exacerbated inflammation or self-reactivity. Many natural compounds have shown to be effective inductors of HO-1 without cytotoxic effects; among them, most are chemicals present in plants used as food, flavoring, and medicine. Here we discuss some naturally derived compounds involved in HO-1 induction, their impact in the immune response modulation, and the beneficial effect in diverse autoimmune disorders. We conclude that the use of some compounds from natural sources able to induce HO-1 is an attractive lifestyle toward promoting human health. This review opens a new outlook on the investigation of naturally derived HO-1 inducers, mainly concerning autoimmunity.

Erythronium japonicum Alleviates Inflammatory Pain by Inhibiting MAPK Activation and by Suppressing NF-κB Activation via ERK/Nrf2/HO-1 Signaling Pathway

Microglial activation-mediated neuroinflammation influences the development of inflammatory pain. The aim of this study was to investigate the anti-inflammatory effects and mechanisms of aqueous Erythronium japonicum extract (EJE) in microglia activation-mediated inflammatory pain. EJE was found to suppress lipopolysaccharide (LPS)-induced inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), ionized calcium-binding adapter molecule 1 (IBA-1), and pro-inflammatory cytokines in BV2 microglial cells. In addition, LPS-induced c-Jun NH₂ terminal protein kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) phosphorylation were inhibited by EJE. Intriguingly, EJE also inhibited p65 phosphorylation by activating extracellular signal-regulated kinase-1/2 (ERK)/nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling. Furthermore, the effects of EJE treatment, such as HO-1 induction and the reduction of NF-ĸB activation, were reversed by ERK1/2 inhibition. In an inflammatory pain mouse model, Complete Freund’s Adjuvant (CFA)-induced mechanical allodynia and foot swelling were alleviated by the oral administration of EJE. Consistent with in vitro results, EJE increased HO-1, while decreasing CFA-induced COX-2, IBA-1, and pro-inflammatory cytokines in the spinal cord. Among the components of EJE, butanol most heavily suppressed LPS-induced microglial activation and increased HO-1 expression. These findings indicate that EJE can alleviate inflammatory pain by inhibiting p38 and JNK and by suppressing NF-ĸB via ERK/Nrf2/HO-1 signaling.

Melatonin Act as an Antidepressant via Attenuation of Neuroinflammation by Targeting Sirt1/Nrf2/HO-1 Signaling

Physical or psychological stress can cause an immunologic imbalance that disturbs the central nervous system followed by neuroinflammation. The association between inflammation and depression has been widely studied in recent years, though the molecular mechanism is still largely unknown. Thus, targeting the signaling pathways that link stress to neuroinflammation might be a useful strategy against depression. The current study investigated the protective effect of melatonin against lipopolysaccharide (LPS)-induced neuroinflammation and depression. Our results showed that LPS treatment significantly induced depressive-like behavior in mice. Moreover, LPS-treatment enhanced oxidative stress, pro-inflammatory cytokines including TNFα, IL-6, and IL-1β, NF-κB phosphorylation, and glial cell activation markers including GFAP and Iba-1 in the brain of mice. Melatonin treatment significantly abolished the effect of LPS, as indicated by improved depressive-like behaviors, reduced cytokines level, reduced oxidative stress, and normalized LPS-altered Sirt1, Nrf2, and HO-1 expression. However, the melatonin protective effects were reduced after luzindole administration. Collectively, it is concluded that melatonin receptor-dependently protects against LPS-induced depressive-like behaviors via counteracting LPS-induced neuroinflammation.

Taraxacum officinale Wigg. Attenuates Inflammatory Responses in Murine Microglia through the Nrf2/HO-1 and NF-κB Signaling Pathways

As a long-established medicinal and edible homologous plant, Taraxacum officinale Wigg. is widely distributed in Asia, Europe, and other parts of the world. T. officinale is reported to exert a variety of biological and pharmacological activities, including anticancer, hepatoprotective, and anti-obesity effects. In this study, we evaluated the anti-inflammatory effects of ethanol extracts of T. officinale (A-TOW) by examining the suppression of proinflammatory mediators in LPS-stimulated BV2 and mouse hippocampus. Furthermore, A-TOW also inhibited the nuclear translocation of nuclear factor κB p65 caused by stimulation with LPS. In addition, A-TOW regulates heme oxygenase (HO)-1 expression through the nuclear translocation of nuclear factor E2-related factor 2 (Nrf2) in BV2 cells. The effects of A-TOW on the over-expression of proinflammatory mediators were partially reversed by transfection of the cells with HO-1 siRNA. These findings suggest that the potent anti-inflammatory activity of T. officinale, possibly through the regulation of Nrf2/HO-1 and NF-κB signaling pathway.

Metabolomic Determination of Specialized Metabolites Using Liquid Chromatography-Tandem Mass Spectrometry in the Traditional Chinese Medicines Astragali Radix and Hedysari Radix

The Traditional Chinese Medicines (TCMs) Astragali Radix (AR) derived from Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao and A. membranaceus (Fisch.) Bge., and Hedysari Radix (HR) derived from Hedysarum polybotrys Hand.-Mazz. (family Leguminosae) are well-known for increasing the tonic effects on “Qi.” A better insight into the specialized (secondary) metabolites is essential to understand the effects of TCM; however, such metabolites remain largely unknown. Here, we performed a metabolomics-based analysis using liquid chromatography-tandem mass spectrometry in 3 plant tissues—periderm, phloem, and xylem—to identify potential bioactive metabolites. Multivariate statistical analysis revealed 29 metabolites showing a significant difference between groups and 10 biomarker candidates of AR and HR. An anti-inflammatory assay showed that the xylem of both AR and HR and the phloem of HR showed higher anti-inflammatory activity than the positive control quercetin in terms of nitric oxide inhibition.

Astragaloside IV Alleviates the Myocardial Damage Induced by Lipopolysaccharide via the Toll-Like Receptor 4 (TLR4)/Nuclear Factor kappa B (NF-κB)/Proliferator-Activated Receptor α (PPARα) Signaling Pathway

BACKGROUND We previously reported that astragaloside IV (As-IV) can alleviate myocardial damage induced by lipopolysaccharide (LPS). However, the anti-inflammatory effects of As-IV following LPS stimulation in mice and H9C2 cardiomyocytes remain unclear. The present study was designed to explore the mechanism of action of As-IV. MATERIAL AND METHODS In vivo, C57BL/6J mice were randomly divided into 5 groups: the control group, the LPS group (10 mg/kg), and 3 LPS groups receiving different doses of As-IV (20, 40, and 80 mg/kg). The protective effect of As-IV on LPS-stimulated H9C2 cardiomyocytes was evaluated in vitro. Cardiac function was detected by echocardiography, and H&E staining was used to evaluate morphologic changes. Cardiomyocyte viability was detected by MTT assay. ELISA was used to detect free fatty acid (FFA), interleukin-6 (IL-6), interleukin-1ß (IL-1ß), and tumor necrosis factor alpha (TNF-alpha) levels in mouse serum and in cell supernatant. Adenosine triphosphate (ATP) and adenosine monophosphate (AMP) contents in myocardial tissues and cells were detected by high-performance liquid chromatography. ATP5D and TLR4/NF-kappaB/PPARalpha signaling pathway proteins (TLR4, NF-kappaB, p65, and PPARalpha) were detected by Western blotting. RESULTS As-IV significantly improved cardiac function, myocardial cell viability, and pathological changes and reduced FFA, IL-1ß, IL-6, and TNF-alpha levels. The ATP/AMP ratio in the cardiac tissues of mice and in H9C2 cardiomyocytes was increased compared to that in the LPS group. In addition, As-IV enhanced ATP synthase and PPARalpha protein expression. In H9C2 cardiomyocytes, the p65-specific inhibitor BAY11-7082 exerted similar effects as As-IV. CONCLUSIONS As-IV alleviates LPS-induced myocardial damage by modulating TLR4/NF-kappaB/PPARalpha signaling-mediated energy biosynthesis.

Interleukin-33 reduces neuronal damage and white matter injury via selective microglia M2 polarization after intracerebral hemorrhage in rats

Interleukin-33 (IL-33) is closely related to the regulation of immunological cells, and its receptor ST2 is a member of the interleukin-1 (IL-1) receptor family. Inflammatory responses play critical roles in neuronal damage and white matter injury (WMI) post intracerebral hemorrhage (ICH). In this study, we tried to explore the role of IL-33 in neuronal damage and WMI after ICH and the underlying mechanisms. The in vivo ICH model was performed by autologous whole blood injection into the right basal ganglia in rats. Immunoblotting, immunofluorescence, brain water content measurement, FJB staining, and TUNEL staining were applied in this study. IL-33 expression was increased in whole brain tissues post-ICH, mainly rapidly increased in ipsilateral astrocyte and microglia, but stayed at a low level in neurons. Intracerebroventricular infusion of IL-33 after ICH attenuated short-term and long-term neurological deficits, WMI, neuronal degeneration, cell death and promoted the transformation of microglia phenotype from M1 to M2 in brain tissues after ICH. These results suggest that IL-33 reduces neuronal damage and WMI by promoting microglia M2 polarization after ICH, thereby improving the outcomes of neurological function.

Natural products as a potential modulator of microglial polarization in neurodegenerative diseases

Neurodegenerative diseases (NDs) are characterized by the progressive loss of structure and function of neurons most common in elderly population, mainly including Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS) and multiple sclerosis (MS). Neuroinflammation caused by microglia as the resident macrophages of the central nervous system (CNS) plays a contributory role in the onset and progression of NDs. Activated microglia, as in macrophages, to be heterogeneous, can polarize into M1 (pro-inflammatory) and M2 (anti-inflammatory) functional phenotypes. The former elaborate pro-inflammatory mediators promoting neuroinflammation and neuronal damage. In contrast, the latter generate anti-inflammatory mediators and neurotrophins that inhibit neuroinflammation and promote neuronal healing. Consistently, the regulation of microglial polarization from M1 to M2 phenotype appears as an outstanding therapeutic and preventive approach for NDs treatment. Although non-steroidal anti-inflammatory drugs (NSAIDs) currently used to alleviate M1 microglia-associated neuroinflammation responsible for the development of NDs, these drugs have different degrees of adverse effects and limited efficacy. As the advantages of novel structure, multi-target, high efficiency and low toxicity, natural products as the modulators of microglial polarization have attracted considerable concerns in the therapeutic areas of NDs. In this review, we mainly summarized the therapeutic potential of natural products and their various molecular mechanisms for NDs treatment through modulating microglial polarization. The aim of the current review is expected to be useful to develop innovative modulators of microglial polarization from natural products for the amelioration and treatment of NDs.

Astragaloside IV Protects Against Oxidized Low-Density Lipoprotein (ox-LDL)-Induced Endothelial Cell Injury by Reducing Oxidative Stress and Inflammation

Background

Endothelial injury is the main mechanism of atherosclerosis, and is caused by oxidized low-density lipoprotein (ox-LDL). Astragaloside IV (AS-IV) is the primary active ingredient of the Chinese herb Huangqi, and exhibits antioxidant and anti-inflammatory properties in cardiovascular diseases. This study investigated the protective effect of AS-IV in human umbilical vein endothelial cells (HUVECs).

Material/Methods

HUVEC cells were induced with ox-LDL to establish an in vitro atherosclerosis model. Then HUVECs were pretreated for 1 h with AS-IV at different concentrations (10, 20, and 50 μM) and then exposed to ox-LDL (100 μg/mL) for 48 h. The cell viability, lactate dehydrogenase (LDH) release, apoptosis, migration, intracellular reactive oxygen species (ROS), and NADPH oxidase activity of HUVECs were measured. qRT-PCR was performed to measure the mRNA expressions of Nrf2, HO-1, TNFα, and IL-6. Enzyme-linked immunosorbent assay (ELISA) was performed to measure the supernatant contents of TNFα and IL-6.

Results

Exposure of HUVECs to ox-LDL reduced cell viability and migration, induced apoptosis, and increased intracellular ROS production and NADPH oxidase. Pretreatment with AS-IV (10, 20, and 50 μM) significantly enhanced the cell viability and migration, suppressed LDH release, apoptosis, ROS production, and NADPH oxidase in HUVECs, in a concentration-dependent manner. The AS-IV (50 μM) alone did not show significant differences from control. AS-IV increased mRNA expressions of Nrf2 and HO-1 and decreased mRNA expressions of TNFα and IL-6 in the ox-LDL-HUEVC cells. Furthermore, AS-IV reduced supernatant contents of TNFα and IL-6.

Conclusions

Astragaloside IV prevents ox-LDL-induced endothelial cell injury by reducing apoptosis, oxidative stress, and inflammatory response.

Association of astragaloside IV-inhibited autophagy and mineralization in vascular smooth muscle cells with lncRNA H19 and DUSP5-mediated ERK signaling

Defective autophagy in vascular smooth muscle cells (VSMCs) is the principal cause of atherosclerosis. This study aimed to investigate the effect of astragaloside IV (AS-IV) on VSMCs autophagy. In vivo, ApoE^-/- mice were fed with high-fat diet ad libitum for eight weeks, with or without AS-IV (25 mg/kg, daily). In vitro, human VSMCs were cultured and treated with β-Glycerophosphate (10 mmol/L) and AS-IV (50 μg/ml). VSMCs autophagy, mineralization, expression of p-ERK1/2, p-mTOR, and autophagy-related proteins (LC3 II/I, p62, and Beclin 1) were detected. Increased autophagy and mineralization was observed in VSMCs in thoracic aorta of mice and in in vitro VSMCs model of atherosclerosis. AS-IV administration attenuated the autophagy and mineralization in VSMCs. Reverse expression profiles of H19 and DUSP5 were observed. AS-IV inhibited DUSP5 and autophagy-related proteins and increased expression of H19, level of p-ERK1/2 and p-mTOR. Further, autophagy and mineralization level in VSMCs were in line with DUSP5 expression level, but in contrast to H19, p-ERK1/2, and p-mTOR profiles. We demonstrated that AS-IV could attenuate autophagy and mineralization of VSMCs in atherosclerosis, which may be associated with H19 overexpression and DUSP5 inhibition.

Astragaloside IV ameliorates high glucose‑induced renal tubular epithelial‑mesenchymal transition by blocking mTORC1/p70S6K signaling in HK‑2 cells

Astragaloside IV (AST) is the major active saponin in Astragalus membranaceus and, reportedly, has a variety of pharmacological activities. However, the potential of AST to ameliorate high glucose‑mediated renal tubular epithelial‑mesenchymal transition (EMT) remains undetermined. The aim of the present research was to explore the effect and mechanism of AST in EMT of renal tubular epithelial cells, as an underlying mechanism of renal fibrosis and a vital feature involved in diabetic nephropathy. The effect of AST on the EMT of renal tubular epithelial cells (HK‑2) stimulated by high glucose was investigated and it was attempted to elucidate the potential underlying mechanism. The expression of E‑cadherin and α‑smooth muscle actin were determined by western blotting and immunofluorescence assays. The expression of the mammalian target of rapamycin complex 1 (mTORC1)/ ribosomal protein S6 kinase β‑1 (p70S6K) signaling pathway and protein levels of four transcriptional factors (snail, slug, twist and zinc finger E‑box‑binding homeobox 1) were also determined by western blotting. Additionally, extracellular matrix components, including fibronectin (FN) and collagen type IV (Col IV) were detected by ELISA. The results suggested that the EMT of HK‑2 cells and the mTORC1/p70S6K pathway were activated by high glucose. The expression of snail and twist in HK‑2 cells was elevated by high glucose. Furthermore, extracellular matrix components, FN and Col IV, were increased in HK‑2 cells cultured with high glucose. In turn, treatment with AST reduced EMT features in HK‑2 cells, inhibited mTORC1/p70S6K pathway activation, downregulated expression of snail and twist, and reduced secretion of FN and Col IV. In summary, the findings suggested that AST ameliorates high glucose‑mediated renal tubular EMT by blocking the mTORC1/p70S6K signaling pathway in HK‑2 cells.

Calcium Sensing Receptor-Related Pathway Contributes to Cardiac Injury and the Mechanism of Astragaloside IV on Cardioprotection

Activation of calcium sensing receptor (CaSR) contributes to cardiac injury, but the underlying mechanism has not yet been examined. Astragaloside IV (AsIV) was previously reported to exhibit protective effects against various myocardial injuries. The aim of the present study was to investigate the underlying mechanism of CaSR in cardiac hypertrophy and apoptosis and to evaluate whether the protective effect of AsIV against myocardial injury is associated with CaSR and its related signaling pathway. In vivo and in vitro myocardial injury was induced by isoproterenol (Iso) or GdCl₃ (a CaSR agonist) in rats and heart H9C2 cells. Cardiac cell hypertrophy, apoptosis, function, Mitochondrial Membrane Potential (MMP), mitochondrial ultrastructure, and [Ca²⁺]_i, as well as the protein expression of CaSR, calcium/calmodulin-dependent protein kinase II (CaMKII), calcineurin (CaN), sarcoplasmic reticulum Ca²⁺-ATPase2a (SERCA2a), and the inositol 1,4,5-trisphosphate receptor (IP3R), were measured in vivo and/or in vitro. The results showed that AsIV attenuated cardiac hypertrophy and apoptosis and attenuated impairments in cardiac function, mitochondrial structure, and MMP induced by Iso or GdCl₃ in rat myocardial tissue and H9C2 cells. Importantly, AsIV treatment inhibited the enhancement of [Ca²⁺]_i and CaSR expression induced by Iso or GdCl₃, an effect similar to that of the CaSR antagonist NPS2143. In addition, AsIV treatment repressed CaSR, CaMKII, and CaN activation and inhibited NFAT-3 nuclear translocation. Mechanistic analysis using lentivirus infection showed that CaSR overexpression activated the CaMKII and CaN signaling pathways and that this response was enhanced by Iso. The results suggested that CaSR-mediated changes in [Ca²⁺]_i and CaMKII and CaN signaling pathways contribute to cardiac hypertrophy and apoptosis and are involved in the protective effect of astragaloside IV against cardiac injury.

Astragaloside IV Inhibits the Progression of Non-Small Cell Lung Cancer Through the Akt/GSK-3β/β-Catenin Pathway

Astragaloside IV (AS-IV) is an active ingredient in Astragalus membranaceus and is involved in various biological processes, such as regulating the immune system, and counteracting inflammation and malignancy. The aim of this study was to explore the effect of AS-IV on non-small cell lung cancer (NSCLC) cells. Cell counting kit (CCK)-8 assay and flow cytometry were performed to investigate cell survival and cell death, and Western blotting was performed to assess protein expression. We found that AS-IV inhibited the migration and proliferation of NSCLC cells and caused a noticeable increase in cell death. Furthermore, the expression of Bax, a marker of cell death, was increased, whereas the expression of Bcl-2, an antiapoptotic protein, was reduced. AS-IV also promoted cleavage of caspase-3, another indication of apoptosis. Finally, the Akt/GSK-3β/β-catenin axis was suppressed in response to AS-IV. Taken together, these findings provide evidence that AS-IV inhibits NSCLC development via inhibition of the Akt/GSK-3β/β-catenin signaling axis. We therefore propose that AS-IV represents a promising novel agent for the treatment of NSCLC.

Astragaloside IV reduces the hypoxia-induced injury in PC-12 cells by inhibiting expression of miR-124

BACKGROUND

Astragalus membranaceus has been clinically used in cerebral ischemia treatment in China and its main component, Astragaloside IV (Ast IV) shows anti-hypoxia activity, but the underlying mechanism has not been clearly clarified. This study was aimed to investigate the effects of Ast IV on hypoxia-induced injury in PC-12 cells as well as the underlying mechanism.

METHODS

Relative miR-124 expression was detected by qRT-PCR. Hic-5 expression was analyzed by qRT-PCR and Western blot. To alter miR-124 and Hic-5 expressions, cells were respectively transfected with miR-124 mimic and pEX-Hic-5. Cell proliferation and apoptosis were measured by BrdU assay and Annexin V-fluorescein isothiocynate (FITC)/propidium iodide (PI) double staining method, respectively. Besides, apoptotic proteins and cell proliferation-associated factors were analyzed by Western blot.

RESULTS

Ast IV alleviated hypoxia-induced injury in PC-12 cells by decreasing apoptosis (P <  0.01). Ast IV inhibited up-regulation of miR-124 induced by hypoxia (P <  0.01). miR-124 mimic impaired the anti-apoptotic effect of Ast IV on PC-12 cells (P <  0.01). Hic-5 expression was significantly down-regulated in miR-124 overexpressed cells (P <  0.001) and Hic-5 overexpression activated Sp1/Survivin signaling pathway (P <  0.001).

CONCLUSION

Ast IV could ameliorate hypoxia-induced injury in PC-12 cells by decreasing miR-124 expression and then up-regulating Hic-5 expression.

Differential Regulation of NF-κB and Nrf2 by Bojungikki-Tang Is Associated with Suppressing Lung Inflammation

Bojungikki-tang (BT), an Asian herbal remedy, has been prescribed to increase the vitality of debilitated patients. Since a compromised, weakened vitality often leads to illness, BT has been widely used to treat various diseases. However, little is known about the mechanism by which BT exerts its effect. Given that BT ameliorates inflammatory pulmonary diseases including acute lung injury (ALI), we investigated whether BT regulates the function of key inflammatory factors such as NF-κB and Nrf2, contributing to suppressing inflammation. Results show that BT interrupted the nuclear localization of NF-κB and suppressed the expression of the NF-κB-dependent genes in RAW 264.7 cells. In similar experiments, BT induced the nuclear localization of Nrf2 and the expression of the Nrf2-dependent genes. In a lipopolysaccharide-induced ALI mouse model, a single intratracheal administration of BT to mouse lungs ameliorated alveolar structure and suppressed the expression of proinflammatory cytokine genes and neutrophil infiltration to mouse lungs. Therefore, our findings suggest that suppression of NF-κB and activation of Nrf2, by which BT suppresses inflammation, are ways for BT to exert its effect.