Kaempferol alleviates LPS-induced neuroinflammation and BBB dysfunction in mice via inhibiting HMGB1 release and down-regulating TLR4/MyD88 pathway

Post-Translational Modification of HMGB1 Disulfide Bonds in Stimulating and Inhibiting Inflammation

High mobility group box 1 protein (HMGB1), a highly conserved nuclear DNA-binding protein, is a “damage-associated molecular pattern” molecule (DAMP) implicated in both stimulating and inhibiting innate immunity. As reviewed here, HMGB1 is an oxidation-reduction sensitive DAMP bearing three cysteines, and the post-translational modification of these residues establishes its proinflammatory and anti-inflammatory activities by binding to different extracellular cell surface receptors. The redox-sensitive signaling mechanisms of HMGB1 also occupy an important niche in innate immunity because HMGB1 may carry other DAMPs and pathogen-associated molecular pattern molecules (PAMPs). HMGB1 with DAMP/PAMP cofactors bind to the receptor for advanced glycation end products (RAGE) which internalizes the HMGB1 complexes by endocytosis for incorporation in lysosomal compartments. Intra-lysosomal HMGB1 disrupts lysosomal membranes thereby releasing the HMGB1-transported molecules to stimulate cytosolic sensors that mediate inflammation. This HMGB1-DAMP/PAMP cofactor pathway slowed the development of HMGB1-binding antagonists for diagnostic or therapeutic use. However, recent discoveries that HMGB1 released from neurons mediates inflammation via the TLR4 receptor system, and that cancer cells express fully oxidized HMGB1 as an immunosuppressive mechanism, offer new paths to targeting HMGB1 for inflammation, pain, and cancer.

Blood-Brain Barrier Disruption by Lipopolysaccharide and Sepsis-Associated Encephalopathy

As a complex multicellular structure of the vascular system at the central nervous system (CNS), the blood-brain barrier (BBB) separates the CNS from the system circulation and regulates the influx and efflux of substances to maintain the steady-state environment of the CNS. Lipopolysaccharide (LPS), the cell wall component of Gram-negative bacteria, can damage the barrier function of BBB and further promote the occurrence and development of sepsis-associated encephalopathy (SAE). Here, we conduct a literature review of the direct and indirect damage mechanisms of LPS to BBB and the relationship between these processes and SAE. We believe that after LPS destroys BBB, a large number of inflammatory factors and neurotoxins will enter and damage the brain tissue, which will activate brain immune cells to mediate inflammatory response and in turn further destroys BBB. This vicious circle will ultimately lead to the progression of SAE. Finally, we present a succinct overview of the treatment of SAE by restoring the BBB barrier function and summarize novel opportunities in controlling the progression of SAE by targeting the BBB.

TLR4-IN-C34 Inhibits Lipopolysaccharide-Stimulated Inflammatory Responses via Downregulating TLR4/MyD88/NF-κB/NLRP3 Signaling Pathway and Reducing ROS Generation in BV2 Cells

TLR4 signal activated by lipopolysaccharide (LPS) is involved in the pathological process of the central nervous system (CNS) diseases and the suppression of TLR4 signal may become an effective treatment. TLR4-IN-C34, a TLR4 inhibitor, is expected to become a candidate compound with anti-neuroinflammatory response. In the present study, the anti-neuroinflammatory effects and possible mechanism of TLR4-IN-C34 were investigated in BV2 microglia cells stimulated by LPS. The results showed that TLR4-IN-C34 decreased the levels of pro-inflammatory factors and chemokines including NO, TNF-α, IL-1β, IL-6, and MCP-1 in the supernatant of LPS-stimulated BV2 cells. Further research indicated that TLR4-IN-C34 suppressed the expression or phosphorylation levels of inflammatory proteins regarding TLR4/MyD88/NF-κB/NLRP3 signaling pathway. In addition, TLR4-IN-C34 reduced ROS production in BV2 cells after LPS treatment. In conclusion, our findings suggest that anti-neuroinflammatory activity of TLR4-IN-C34 may be interrelated to the inhibition of TLR4/MyD88/NF-κB/NLRP3 signaling pathway and reduction of ROS generation.

Shenjinhuoxue Mixture Attenuates Inflammation, Pain, and Cartilage Degeneration by Inhibiting TLR-4 and NF-κB Activation in Rats with Osteoarthritis: A Synergistic Combination of Multitarget Active Phytochemicals

Osteoarthritis (OA), a highly prevalent chronic joint disease, involves a complex network of inflammatory mediators that not only triggers pain and cartilage degeneration but also accelerates disease progression. Traditional Chinese medicinal shenjinhuoxue mixture (SHM) shows anti-inflammatory and analgesic effects against OA with remarkable clinical efficacy. This study explored the mechanism underlying anti-OA properties of SHM and evaluated its efficacy and safety via in vivo experiments. Through network pharmacology and published literature, we identified the key active phytochemicals in SHM, including β-sitosterol, oleanolic acid, licochalcone A, quercetin, isorhamnetin, kaempferol, morusin, lupeol, and pinocembrin; the pivotal targets of which are TLR-4 and NF-κB, eliciting anti-OA activity. These phytochemicals can enter the active pockets of TLR-4 and NF-κB with docking score ≤ -3.86 kcal/mol, as shown in molecular docking models. By using surface plasmon resonance assay, licochalcone A and oleanolic acid were found to have good TLR-4-binding affinity. In OA rats, oral SHM at mid and high doses (8.72 g/kg and 26.2 g/kg) over 6 weeks significantly alleviated mechanical and thermal hyperalgesia (P < 0.0001). Accordingly, the expression of inflammatory mediators (TLR-4, interleukin (IL-) 1 receptor-associated kinase 1 (IRAK1), NF-κB-p65, tumor necrosis factor (TNF-) α, IL-6, and IL-1β), receptor activator of the NF-κB ligand (RANKL), and transient receptor potential vanilloid 1 (TRPV1) in the synovial and cartilage tissue of OA rats was significantly decreased (P < 0.05). Moreover, pathological observation illustrated amelioration of cartilage degeneration and joint injury. In chronic toxicity experiment of rats, SHM at 60 mg/kg demonstrated the safety. SHM had an anti-inflammatory effect through a synergistic combination of active phytochemicals to attenuate pain and cartilage degeneration by inhibiting TLR-4 and NF-κB activation. This study provided the experimental foundation for the development of SHM into a more effective dosage form or new drugs for OA treatment.

Heparin alleviates LPS-induced endothelial injury by regulating the TLR4/MyD88 signaling pathway

Heparin is a commonly used in the clinic, however, Heparin's effect on endothelial injury remains unclear. The aim of the present study was to evaluate the effects and possible mechanisms of action underlying heparin treatment in lipopolysaccharide (LPS)-induced endothelial injury in vitro. TNF-α, IL-1β, IL-6 and IFN-γ levels were measured using ELISA. Cell proliferation was measured using a 5-ethynyl-2'-deoxyuridine (EdU) assay. The number of apoptotic cells and apoptotic rate were evaluated using TUNEL assays and flow cytometry, respectively. Toll-like receptor 4 (TLR4), myeloid differentiation primary response 88 (MyD88) and NF-κB (p65) gene expression was evaluated using reverse transcription-quantitative PCR, whilst TLR4, MyD88 and p-NF-κB (p65) protein expression was evaluated using western blot analysis. The levels of phosphorylated NF-κB in the nucleus were evaluated using cellular immunofluorescence. Compared with those in the normal control group, TNF-α, IL-1β, IL-6 and IFN-γ levels were significantly increased in the LPS group (P<0.001). In addition, 5-ethynyl-2'-deoxyuridine (EdU)-positive cells were significantly increased and apoptosis was significantly decreased (P<0.001). TLR4, MyD88 and NF-κB (p65) expression was also significantly increased (P<0.001). Compared with those in the LPS group, following heparin treatment, TNF-α, IL-1β, IL-6 and IFN-γ levels were significantly decreased (P<0.05), whilst the number of EdU-positive cells was significantly increased and the level of apoptosis was significantly decreased (P<0.05). TLR4, MyD88 and NF-κB (p65) expression was also significantly decreased by heparin in a dose-dependent manner (P<0.001). Small interfering RNA-TLR4 transfection exerted similar effects to those mediated by heparin in alleviating endothelial injury. In conclusion, heparin suppressed LPS-induced endothelial injury through the regulation of TLR4/MyD88/NF-κB (p65) signaling in vitro.

Potential of Sorghum Polyphenols to Prevent and Treat Alzheimer's Disease: A Review Article

Alzheimer's disease (AD) is characterized by the excessive deposition of extracellular amyloid-beta peptide (Aβ) and the build-up of intracellular neurofibrillary tangles containing hyperphosphorylated tau proteins. This leads to neuronal damage, cell death and consequently results in memory and learning impairments leading to dementia. Although the exact cause of AD is not yet clear, numerous studies indicate that oxidative stress, inflammation, and mitochondrial dysfunction significantly contribute to its onset and progression. There is no effective therapeutic approach to stop the progression of AD and its associated symptoms. Thus, early intervention, preferably, pre-clinically when the brain is not significantly affected, is a better option for effective treatment. Natural polyphenols (PP) target multiple AD-related pathways such as protecting the brain from Aβ and tau neurotoxicity, ameliorating oxidative damage and mitochondrial dysfunction. Among natural products, the cereal crop sorghum has some unique features. It is one of the major global grain crops but in the developed world, it is primarily used as feed for farm animals. A broad range of PP, including phenolic acids, flavonoids, and condensed tannins are present in sorghum grain including some classes such as proanthocyanidins that are rarely found in others plants. Pigmented varieties of sorghum have the highest polyphenolic content and antioxidant activity which potentially makes their consumption beneficial for human health through different pathways such as oxidative stress reduction and thus the prevention and treatment of neurodegenerative diseases. This review summarizes the potential of sorghum PP to beneficially affect the neuropathology of AD.

A Network Pharmacology Study on the Molecular Mechanism of Protocatechualdehyde in the Treatment of Diabetic Cataract

Purpose

Protocatechualdehyde (PCA) is a phenolic compound found in the roots of Salvia miltiorrhiza with anti-proliferative and antioxidant activities. At present, there are few studies on protocatechualdehyde against diabetic cataract (DC), and there is also lack of systematic research on the mechanism of protocatechualdehyde. Therefore, this study tried to comprehensively clarify the targets and complex mechanisms of PCA against DC from the perspective of network pharmacology.

Materials and Methods

Through collecting relevant targets from the databases, GO and KEGG enrichment analysis were performed on the potential targets. Moreover, core genes were identified by topological analysis of protein-protein interaction (PPI) network and gene-phenotype correlation analysis.

Results

The results indicated that protocatechualdehyde may be closely related to targets such as AKT1, MAPK3 and HDAC3, as well as signal pathways such as MAPK signaling pathway, PI3K-Akt signaling pathway and AGE-RAGE signaling pathway in diabetic complications.

Conclusion

Together, the present study systematically clarified the possible mechanisms of protocatechualdehyde in the treatment of diabetic cataract and provided new ideas for the drug research of this disease.

Advance toward isolation, extraction, metabolism and health benefits of kaempferol, a major dietary flavonoid with future perspectives

As a major ubiquitous secondary metabolite, flavonoids are widely distributed in planta. Among flavonoids, kaempferol is a typical natural flavonol in diets and medicinal plants with myriad bioactivities, such as anti-inflammatory activity, anti-cancer activity, antioxidant activity, and anti-diabetic activity. However, the natural sources, absorption and metabolism as well as the bioactivities of kaempferol have not been reviewed comprehensively and systematically. This review highlights the latest research progress and the effect of kaempferol in the prevention and treatment of various chronic diseases, as well as its protective health effects, and provides a theoretical basis for future research to be used in nutraceuticals. Further, comparison of the different extraction and analytical methods are presented to highlight the most optimum for PG recovery and its detection in plasma and body fluids. Such review aims at improving the value-added applications of this unique dietary bioactive flavonoids at commercial scale and to provide a reference for its needed further development.

Distinct effects of different doses of kaempferol on D‑GalN/LPS‑induced ALF depend on the autophagy pathway

Kaempferol, a flavonoid compound, has various biological functions, such as anti-inflammatory and antitumor activities. Acute liver failure (ALF) is a lethal clinical syndrome that occurs due to severe damage of the liver function. In the present study, the mechanisms underlying the therapeutic effects of kaempferol in ALF were evaluated. An ALF mouse model was established using D-galactosamine (D-GalN; 700 mg/kg)/lipopolysaccharide (LPS; 10 µg/kg). A total of 2 h before the administration of D-GalN/LPS, mice were pretreated with different doses of kaempferol (2.5, 5, 10, 20 and 40 mg/kg), and 6 h after injection of D-GalN/LPS, mice were euthanized. The survival rate, liver function and levels of inflammatory cytokines were assessed. The results demonstrated that kaempferol pretreatment protected hepatocytes from ALF induced by D-GalN/LPS via regulation of the autophagy pathway, both in vivo and in vitro. Pretreatment with a high dose of kaempferol significantly decreased the survival rates and increased severe liver damage; however, pretreatment with a low dose of kaempferol had the opposite effect. Furthermore, pretreatment with a high dose of kaempferol enhanced the levels of proinflammatory cytokines [TNF-α, IL-6, IL-12p40, IL-1β, C-X-C motif chemokine ligand (CXCL)-2, CXCL-10] and markers of the MAPK signaling pathway [phosphorylated (p)-JNK, p-ERK, p-p38], whereas pretreatment with a low dose of kaempferol had the opposite effect. Pretreatment with a high dose of kaempferol decreased autophagy, whereas pretreatment with a low dose of kaempferol increased autophagy in vivo and in vitro. It was also shown that pretreatment with 3-methyadenine or autophagy related 7 small interfering RNA, to inhibit autophagy, partially abrogated the hepatoprotective effects of pretreatment with 5 mg/kg kaempferol in the ALF mouse model. These results demonstrate that the effects of different doses of kaempferol on D-GalN/LPS-induced ALF varies based on the dose, and that kaempferol exerted its effects via regulation of the autophagy pathway.

RKC-B1 Blocks Activation of NF-κB and NLRP3 Signaling Pathways to Suppress Neuroinflammation in LPS-Stimulated Mice

RKC-B1 is a novel fermentation product obtained from the marine micromonospora FIM02-523A. Thus far, there have been few reports about the pharmacological activity of RKC-B1. In our present study, we investigated the anti-neuroinflammatory effects and the possible mechanism of RKC-B1 in LPS-stimulated mice. After treatment with RKC-B1, RNA-seq transcriptome of the cerebral cortex tissue was conducted to find the differentially expressed genes (DEGs). Inflammatory cytokines and proteins were evaluated by ELISA and WB. In RNA-seq analysis, there were 193 genes screened as core genes of RKC-B1 for treatment with neuroinflammation. The significant KEGG enrichment signaling pathways of these core genes were mainly included TNF signaling pathway, IL-17 signaling pathway, NOD-like receptor signaling pathway, NF-κB signaling pathway and others. The corresponding top five KEGG enrichment pathways of three main clusters in PPI network of core genes were closely related to human immune system and immune disease. The results showed that RKC-B1 reduced the levels of pro-inflammatory factors (IL-6, IL-1β, MCP-1, and ICAM-1) and the expression of COX2 in cerebral cortex tissue. Additionally, we found that the anti-neuroinflammation activity of RKC-B1 might be related to suppress activating of NF-κB and NLRP3/cleaved caspase-1 signaling pathways. The current findings suggested that RKC-B1 might be a promising anti-neuroinflammatory agent.

Exploring the Mechanism of Indigo Naturalis in the Treatment of Ulcerative Colitis Based on TLR4/MyD88/NF-κB Signaling Pathway and Gut Microbiota

Background: Clinical trials have proven that indigo naturalis is a candidate drug for treating ulcerative colitis (UC), but its therapeutic mechanism is still unclear.

Purpose: This study aimed to evaluate the protective effect and mechanism of indigo naturalis to treat mice with dextran sulfate sodium (DSS)-induced UC.

Methods: DSS-induced UC mice were treated with indigo naturalis (200 mg/kg), indigo (4.76 mg/kg), and indirubin (0.78 mg/kg) for 1 week. The anti-UC mechanism of indigo naturalis was studied by pathological section, inflammatory factor, western blot, and 16S rRNA sequencing.

Results: According to body weight change, disease activity index, and colon length, indigo naturalis had the strongest anti DSS-induced UC effect, followed by indirubin and indigo. Pathological section showed that indigo naturalis, indigo, and indirubin could reduce the infiltration of inflammatory cells, increase the secretion of intestinal mucus, and repair the intestinal mucosa. Indigo naturalis, indigo, and indirubin could reduce IL-1β,IL-6, and TNF-α by inhibiting TLR4/MyD88/NF-κB signal transduction. Indigo naturalis and indigo could also reduce IgA and IgG both in serum and colon tissue. In addition, indigo naturalis, indigo, and indirubin could adjust the gut microbiota structure of DSS-induced UC mice, reducing the ratio of Firmicutes/Bacteroidetes and increasing the abundance of probiotics.

Conclusion: Indigo and indirubin are one of the main anti-UC components of indigo naturalis. INN could regulate intestinal flora, reduce inflammation, repair intestinal mucosa, and improve the physiological status of DSS-induced UC mice and its anti-UC mechanism may be involved in inhibiting TLR4/MyD88/NF-κB signal transduction.

Baicalin protects LPS-induced blood-brain barrier damage and activates Nrf2-mediated antioxidant stress pathway

The integrity of the BBB is closely related to brain microvascular endothelial cells and TJs, and its dysfunction can lead to stroke, multiple sclerosis, extracranial injury and neurodegenerative diseases. Baicalin is one of the main bioactive extracts from Scutellaria Baicalensis Georgi, which has anti-inflammatory and anti-oxidation pharmacological functions. Preventive protection with baicalin for seven consecutive days can significantly improve the appearance of cell apoptosis and Fluorescein sodium infiltration in the brain tissue of BALB/C mice. In addition, baicalin can inhibit the production of pro-inflammatory cytokines induced by LPS in mice and bEnd.3 cells, including IL-1β and TNF-α. At the same time, LPS caused a decrease in tight junction proteins in the blood-brain barrier, but baicalin can alleviate the damage of the blood-brain barrier by up-regulating Claudin-5 and ZO-1 protein expression. In addition, the results showed that baicalin reduced the production of ROS and MDA in bEnd.3 cells and promoted the production of SOD, and up-regulated the expression of Nrf2, HO-1 and NQO1. The mechanism of this change was mediated by activating the Nrf2 signaling pathway. All in all, Baicalin protected LPS-induced blood-brain barrier damage and activateed Nrf2-mediated antioxidant stress pathway.

Chrysomycin A Attenuates Neuroinflammation by Down-Regulating NLRP3/Cleaved Caspase-1 Signaling Pathway in LPS-Stimulated Mice and BV2 Cells

Chrysomycin A (Chr-A), an antibiotic chrysomycin, was discovered in 1955 and is used to treat cancer and tuberculosis. In the present study, the anti-neuroinflammatory effects and possible mechanism of Chr-A in BALB/c mice and in BV2 microglia cells stimulated by lipopolysaccharide (LPS) were investigated. Firstly, the cortex tissues of mice were analyzed by RNA-seq transcriptome to identify differentially expressed genes (DEGs) regulated by Chr-A in LPS-stimulated mice. Inflammatory cytokines and inflammatory proteins were detected by enzyme-linked immunosorbent assay and Western blot. In RNAseq detection, 639 differential up-regulated genes between the control group and LPS model group and 113 differential down-regulated genes between the LPS model group and Chr-A treatment group were found, and 70 overlapping genes were identified as key genes for Chr-A against neuroinflammation. Subsequent GO biological process enrichment analysis showed that the anti-neuroinflammatory effect of Chr-A might be related to the response to cytokine, cellular response to cytokine stimulus, and regulation of immune system process. The significant signaling pathways of KEGG enrichment analysis were mainly involved in TNF signaling pathway, cytokine-cytokine receptor interaction, NF-κB signaling pathway, IL-17 signaling pathway and NOD-like receptor signaling pathway. Our results of in vivo or in vitro experiments showed that the levels of pro-inflammatory factors including NO, IL-6, IL-1β, IL-17, TNF-α, MCP-1, CXCL12, GM-CSF and COX2 in the LPS-stimulated group were higher than those in the control group, while Chr-A reversed those conditions. Furthermore, the Western blot analysis showed that its anti-neuroinflammation appeared to be related to the down-regulation of NLRP3/cleaved caspase-1 signaling pathway. The current findings provide new insights into the activity and molecular mechanisms of Chr-A for the treatment of neuroinflammation.

Irbesartan suppresses lipopolysaccharide (LPS)-induced blood-brain barrier (BBB) dysfunction by inhibiting the activation of MLCK/MLC

The basic function of the blood-brain barrier (BBB) is to selectively regulate the infiltration of solutes from the circulating blood into the central nervous system (CNS). Impaired BBB activity is related to brain damage caused by stroke, traumatic injury, neurodegenerative diseases, etc. Comprised of a monolayer of endothelial cells, the integrity of the BBB is determined by the expression of tight junction proteins and the contractile activity of the perijunctional apical actomyosin ring. Irbesartan, an AT1R antagonist, has been widely used for the treatment of hypertension. However, the pharmacological function of Irbesartan in the balance of the BBB is still unknown. In the present study, we performed both in-vivo and in-vitro experiments using lipopolysaccharide (LPS) to explore the mechanism behind the protective effects of Irbesartan against the BBB impairment. The results of our mouse model study revealed that Irbesartan could reduce BBB permeability, restore the expression of Occludin, and suppress the expression of inflammatory mediators, including interleukin-6, monocyte chemoattractant protein-1, and intercellular adhesion molecule-1. Additionally, Irbesartan improved LPS-induced depressive-like behavior. In our in vitro experiments, human brain microvascular endothelial cells (HBMVECs) stimulated with LPS demonstrated decreased endothelial permeability and increased occludin expression in response to Irbesartan treatment. Importantly, we found that the protective effects of Irbesartan were mediated through the NF-κB/MLC/MLCK signaling pathway, as blockage of NF-κB abolished the effects of Irbesartan. Our findings provide a basis for further research into the neuroprotective mechanism of Irbesartan.

Evaluation of Anti-inflammatory Nutraceuticals in LPS-induced Mouse Neuroinflammation Model: An Update

It is known that peripheral infections, accompanied by inflammation, represent significant risk factors for the development of neurological disorders by modifying brain development or affecting normal brain aging. The acute effects of systemic inflammation on progressive and persistent brain damage and cognitive impairment are well documented. Anti-inflammatory therapies may have beneficial effects on the brain, and the protective properties of a wide range of synthetic and natural compounds have been extensively explored in recent years. In our previous review, we provided an extensive analysis of one of the most important and widely-used animal models of peripherally induced neuroinflammation and neurodegeneration - lipopolysaccharide (LPS)-treated mice. We addressed the data reproducibility in published research and summarized basic features and data on the therapeutic potential of various natural products, nutraceuticals, with known anti-inflammatory effects, for reducing neuroinflammation in this model. Here, recent data on the suitability of the LPS-induced murine neuroinflammation model for preclinical assessment of a large number of nutraceuticals belonging to different groups of natural products such as flavonoids, terpenes, non-flavonoid polyphenols, glycosides, heterocyclic compounds, organic acids, organosulfur compounds and xanthophylls, are summarized. Also, the proposed mechanisms of action of these molecules are discussed.

Mechanism of Action of Nicotiflorin from Tricyrtis maculata in the Treatment of Acute Myocardial Infarction: From Network Pharmacology to Experimental Pharmacology

Purpose

Acute myocardial infarction (AMI) is a cardiovascular disease with a high fatality rate. In this study, we combined network pharmacology and experimental pharmacology and discovered the potential mechanism of action and the active ingredients of the lily, Tricyrtis maculata was discovered. The monomer compound with stronger activity was discovered through in vitro cell experiments.

Methods

Forty known compounds were isolated from T. maculata. Using TCMSP, Swiss Target Prediction, metaTarFisher, GeneCards and OMIM databases, targets of drug compositions and AMI-related genes were obtained, and the differential expression genes between AMI and normal tissues were extracted through the GEO database. Then, through an online mapping tool, the intersection genes were obtained to predict the possible effective components of T. maculata that can be used to treat AMI. The top five targets were selected for molecular docking via the protein–protein interaction (PPI) network to verify the binding activity between key compounds and target proteins. GO and KEGG enrichment analyses of the intersection genes were carried out with the program R to further screen key genes and effective compositions. On this basis, the compound with more optimal activity was screened and validated in vitro.

Results

In this study, 40 known monomer components were selected, and 1112 predicted genes, 1655 disease genes, 1425 differentially expressed genes, 1206 GO functions and 127 KEGG pathways were obtained. The results of molecular docking showed that the binding of MMP9 with drug components is stable. Through the comprehensive research of network pharmacology and experimental pharmacology, it was shown that T. maculata intervenes in the process of AMI through multicomponent, multitarget, and multichannel synergistic effects. It is speculated that the anti-AMI effect may be related to the regulation of the Akt/FoxO/BCl signaling pathway. Cellular experiments showed that nicotiflorin has satisfactory anti-inflammatory activity and endothelial protection and can reduce the release of nitric oxide (NO), an inflammatory medium after endothelial cell damage.

Conclusion

This study reveals the therapeutic effect and relative mechanism of extract of T. maculata extract on AMI. Analysis revealed that nicotiflorin from T. maculata is a compound with satisfactory anti-inflammatory activity and endothelial protection, which provides a new direction and treatment basis for further experimental exploration and clinical treatment.

Pretreatment with kaempferol attenuates microglia-mediate neuroinflammation by inhibiting MAPKs-NF-κB signaling pathway and pyroptosis after secondary spinal cord injury

Spinal cord injury (SCI) is a devastating injury that characterized by oxidative stress and inflammatory response. Kaempferol is reported to be an anti-neuroinflammation in neurologic disorders. Nevertheless, the role and mechanism of kaempferol in SCI remains unclear. The present study aims to investigate effects of kaempferol on SCI and its possible underlying mechanisms in in vivo and in vitro models. A C5 hemi-contusion injury was induced in Sprague-Dawley rats to investigate the neuroprotective effects of kaempferol after SCI. For in vitro study, the BV2 microglia cell lines were pretreated with or without kaempferol. A combination of molecular and histological methods was used to clarify the mechanism and explore the signaling pathway both in vivo and in vitro. One-way analysis of variance (ANOVA) was conducted with Bonferroni post hoc tests to examine the differences between groups. The in vivo studies showed that kaempferol could improve the recovery of hindlimb motor function and ameliorate tissue damage in the spinal cord after SCI. Moreover, administration of kaempferol reduced microglia activation and oxidative stress level in the spinal cord. The in vitro studies showed that kaempferol suppressed the microglia activation resulting from the administration of LPS with ATP to BV-2 cells. Pretreated BV2 cells with kaempferol reduced the generation of reactive oxygen species (ROS) by inhibiting NADPH oxidase 4, and then, suppressed the phosphorylation of p38 MAPK and JNK, which subsequently inhibited nuclear translocation of NF-κB p65 to express pro-inflammatory factors. We also observed that kaempferol could inhibite the pyroptosis related proteins (NLRP3 Caspase-1 p10 ASC N-GSDMD) and reduce the release of IL-18 and IL-1β. In conclusion, kaempferol was able to reduce oxidative stress and inflammatory response through down-regulation of ROS dependent MAPKs- NF-κB and pyroptosis signaling pathway, which suggested that kaempferol might be a novel promising therapeutic agent for SCI.

Kaempferol from Penthorum chinense Pursh suppresses HMGB1/TLR4/NF-κB signaling and NLRP3 inflammasome activation in acetaminophen-induced hepatotoxicity

Acetaminophen (APAP) is one of the safest and most effective over-the-counter (OTC) analgesics and antipyretics, but excessive doses of APAP will induce hepatotoxicity with high morbidity and mortality worldwide. Kaempferol (KA), a flavonoid compound derived from the medicinal and edible plant of Penthorum chinense Pursh, has been reported to exert a profound anti-inflammatory and antioxidant activity. In this study, we explored the protective effect and novel mechanism of KA against APAP-induced hepatotoxicity. The results revealed that KA pretreatment significantly reduced the levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), relieved hepatocellular damage and apoptosis, attenuated the exhaustion of glutathione (GSH) and accumulation of malondialdehyde (MDA), increased the expression of antioxidative enzymes (e.g., heme oxygenase 1 (HO-1) and NADPH quinone oxidoreductase 1 (NQO1)), and thus restrained APAP-induced oxidative damage in the liver. KA suppressed the expression of NLRP3 and reduced the levels of pro-inflammatory factors, including interleukin-1 beta (IL-1β), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6). Moreover, KA remarkably inhibited high-mobility group box 1 (HMGB1) and toll-like receptor 4 (TLR4) expression as well as nuclear factor kappa-B (NF-κB) activation for liver protection against APAP-induced inflammatory responses and apoptosis. Taken together, our findings suggested that KA could effectively protect hepatocytes from APAP hepatotoxicity through the up-regulation of HO-1 and NQO1 expression, the down-regulation of NLRP3 expression, and the inhibition of the HMGB1/TLR4/NF-κB signaling pathway.

Meta-Analysis of Methamphetamine Modulation on Amyloid Precursor Protein through HMGB1 in Alzheimer's Disease

The deposition of amyloid-beta (Aβ) through the cleavage of amyloid-beta precursor protein (APP) is a biomarker of Alzheimer’s disease (AD). This study used QIAGEN Ingenuity Pathway Analysis (IPA) to conduct meta-analysis on the molecular mechanisms by which methamphetamine (METH) impacts AD through modulating the expression of APP. All the molecules affected by METH and APP were collected from the QIAGEN Knowledge Base (QKB); 78 overlapping molecules were identified. Upon simulation of METH exposure using the “Molecule Activity Predictor” feature, eight molecules were found to be affected by METH and exhibited activation relationships on APP expression at a confidence of p = 0.000453 (Z-score = 3.51, two-tailed). Core Analysis of these eight molecules identified High Mobility Group Box protein 1 (HMGB1) signaling pathway among the top 5 canonical pathways with most overlap with the 8-molecule dataset. Simulated METH exposure increased APP expression through HMGB1 at a confidence of p < 0.00001 (Z-score = 7.64, two-tailed). HMGB1 is a pathogenic hallmark in AD progression. It not only increases the production of inflammatory mediators, but also mediates the disruption of the blood-brain barrier. Our analyses suggest the involvement of HMGB1 signaling pathway in METH-induced modulation of APP as a potential casual factor of AD.

Role of Adaptor Protein Myeloid Differentiation 88 (MyD88) in Post-Subarachnoid Hemorrhage Inflammation: A Systematic Review

Myeloid differentiation 88 (MyD88) is a well-established inflammatory adaptor protein. It is one of the essential downstream proteins of the toll-like receptor 4 (TLR4) signaling pathway. TLRs are pattern recognition receptors that are usually activated by the damage-associated molecular pattern molecules (DAMPs). Sterile inflammation is triggered by the endogenous DAMPs released in response to global cerebral ischemia and from extravasated blood after subarachnoid hemorrhage (SAH). In this review, we highlight the importance of the neuroinflammatory role of the MyD88 in the SAH. We also explore a few possible pharmacological agents that can be used to decrease SAH-associated neuroinflammation by modulating the MyD88 dependent functions. Pharmacological agents such as flavonoids, melatonin, fluoxetine, pentoxifylline and progesterone have been investigated experimentally to reduce the SAH-associated inflammation. Inhibition of the MyD88 not only reduces the expression of pro-inflammatory cytokines, but also potentially inhibits other processes that can augment the SAH associated inflammation. Further investigations are required to translate these findings in the clinical setting.

Kaempferol induces ROS-dependent apoptosis in pancreatic cancer cells via TGM2-mediated Akt/mTOR signaling

BACKGROUND

Kaempferol, a natural flavonoid, exhibits anticancer properties by scavenging reactive oxygen species (ROS). However, increasing evidence has demonstrated that, under certain conditions, kaempferol can inhibit tumor growth by upregulating ROS levels. In this study, we aimed to investigate whether kaempferol effectively suppresses pancreatic cancer through upregulation of ROS, and to explore the underlying molecular mechanism.

METHODS

PANC-1 and Mia PaCa-2 cells were exposed to different concentrations of kaempferol. Cell proliferation and colony formation were evaluated by CCK-8 and colony formation assays. Flow cytometry was performed to assess the ROS levels and cell apoptosis. The mRNA sequencing and KEGG enrichment analysis were performed to identify differentially expressed genes and to reveal significantly enriched signaling pathways in response to kaempferol treatment. Based on biological analysis, we hypothesized that tissue transglutaminase (TGM2) gene was an essential target for kaempferol to induce ROS-related apoptosis in pancreatic cancer. TGM2 was overexpressed by lentivirus vector to verify the effect of TGM2 on the ROS-associated apoptotic signaling pathway. Western blot and qRT-PCR were used to determine the protein and mRNA levels, respectively. The prognostic value of TGM2 was analyzed by Gene Expression Profiling Interactive Analysis (GEPIA) tools based on public data from the TCGA database.

RESULTS

Kaempferol effectively suppressed pancreatic cancer in vitro and in vivo. Kaempferol promoted apoptosis in vitro by increasing ROS generation, which was involved in Akt/mTOR signaling. TGM2 levels were significantly increased in PDAC tissues compared with normal tissues, and high TGM2 expression was positively correlated with poor prognosis in pancreatic cancer patients. Decreased TGM2 mRNA and protein levels were observed in the cells after treatment with kaempferol. Additionally, TGM2 overexpression downregulated ROS production and inhibited the abovementioned apoptotic signaling pathway.

CONCLUSIONS

Kaempferol induces ROS-dependent apoptosis in pancreatic cancer cells via TGM2-mediated Akt/mTOR signaling, and TGM2 may represent a promising prognostic biomarker for pancreatic cancer.

Chinese Herbs and Repurposing Old Drugs as Therapeutic Agents in the Regulation of Oxidative Stress and Inflammation in Pulmonary Diseases

Several pro-inflammatory factors and proteins have been characterized that are involved in the pathogenesis of inflammatory diseases, including acute respiratory distress syndrome, chronic obstructive pulmonary disease, and asthma, induced by oxidative stress, cytokines, bacterial toxins, and viruses. Reactive oxygen species (ROS) act as secondary messengers and are products of normal cellular metabolism. Under physiological conditions, ROS protect cells against oxidative stress through the maintenance of cellular redox homeostasis, which is important for proliferation, viability, cell activation, and organ function. However, overproduction of ROS is most frequently due to excessive stimulation of either the mitochondrial electron transport chain and xanthine oxidase or reduced nicotinamide adenine dinucleotide phosphate (NADPH) by pro-inflammatory cytokines, such as interleukin-1β and tumor necrosis factor α. NADPH oxidase activation and ROS overproduction could further induce numerous inflammatory target proteins that are potentially mediated via Nox/ROS-related transcription factors triggered by various intracellular signaling pathways. Thus, oxidative stress is considered important in pulmonary inflammatory processes. Previous studies have demonstrated that redox signals can induce pulmonary inflammatory diseases. Thus, therapeutic strategies directly targeting oxidative stress may be effective for pulmonary inflammatory diseases. Therefore, drugs with anti-inflammatory and anti-oxidative properties may be beneficial to these diseases. Recent studies have suggested that traditional Chinese medicines, statins, and peroxisome proliferation-activated receptor agonists could modulate inflammation-related signaling processes and may be beneficial for pulmonary inflammatory diseases. In particular, several herbal medicines have attracted attention for the management of pulmonary inflammatory diseases. Therefore, we reviewed the pharmacological effects of these drugs to dissect how they induce host defense mechanisms against oxidative injury to combat pulmonary inflammation. Moreover, the cytotoxicity of oxidative stress and apoptotic cell death can be protected via the induction of HO-1 by these drugs. The main objective of this review is to focus on Chinese herbs and old drugs to develop anti-inflammatory drugs able to induce HO-1 expression for the management of pulmonary inflammatory diseases.

Gut microbiota dysbiosis in depressed women: The association of symptom severity and microbiota function

BACKGROUND

The association between abnormal gut microbiome composition and depression is well established. However, the composition and functional capacity of the gut microbiota regarding depressed women has been poorly addressed.

METHODS

Stool samples from 62 female patients with major depressive disorder (MDD) and 46 healthy controls (Con) were analyzed by 16S rRNA gene sequencing; Twenty fecal samples from the patient group and 21 fecal samples from the Con group were further analyzed by shotgun metagenomic sequencing. Psychiatric symptoms and psychological, social, and professional functioning was also assessed.

RESULTS

Phylum Bacteroidetes, proteobaeteria, and Fusobacteria were greatly enriched in patients with MDD, while the Firmicutes and Actinobacteria phyla were consistently higher in Con. Notably, 18 microbial markers were identified on a random forest model and achieve an area under the curve of 0.92 between patients with MDD and the Con group. Forty-five species and their associated function were identified with statistically significant differences between patients with MDD and the Con group.

LIMITATIONS

The number of recruited samples, especially samples enrolled for shotgun metagenomic sequencing was relatively small, and the stool samples were collected only at baseline, making it difficult to establish a causal association between changes in gut microbiota compositions and disease remission.

CONCLUSIONS

This study characterizes the gut microbiota and their related function in female MDD. The gut microbiota-based biomarkers may be helpful in diagnosis and the altered gut microbial metabolites may contribute to the pathogenesis of MDD in women, representing potential microbial targets.

Citrus Polyphenols in Brain Health and Disease: Current Perspectives

In addition to essential micronutrients such as vitamin C, citrus fruits represent a considerably rich source of non-essential bioactive compounds, in particular flavanones which form a sub-set of the flavonoid group. Preclinical studies have demonstrated the neuroprotective potential of citrus flavonoids and have highlighted both the well-established (anti-inflammatory and anti-oxidative properties), and newly emerging (influence upon blood-brain barrier function/integrity) mechanistic actions by which these neurological effects are mediated. Encouragingly, results from human studies, although limited in number, appear to support this preclinical basis, with improvements in cognitive performance and disease risk observed across healthy and disease states. Therefore, citrus fruits - both as whole fruit and 100% juices - should be encouraged within the diet for their potential neurological benefit. In addition, there should be further exploration of citrus polyphenols to establish therapeutic efficacy, particularly in the context of well-designed human interventions.

Total flavonoids of Radix Tetrastigma suppress inflammation-related hepatocellular carcinoma cell metastasis

This study aimed to investigate the effects of the total flavonoids of Radix Tetrastigma (RTF) on inflammation-related hepatocellular carcinoma (HCC) development. Extracted RTF was diluted to different concentrations for subsequent experiments. HCC cells were cotreated with lipopolysaccharide (LPS) and RTF to investigate the effects of RTF on LPS-stimulated HCC cells. A CCK-8 kit was used to measure cell proliferation. Apoptosis was detected with a flow cytometer. Cell migration and invasion were quantified by wound healing and Transwell assays, respectively. The expression of TLR4 and COX-2 and activation of the NF-κB pathway were determined by Western blotting. Treatment with LPS significantly enhanced cell proliferation and decreased the apoptosis rate, while cell migration and invasion were notably upregulated. RTF suppressed the proliferation and invasion induced by LPS stimulation and promoted HCC cell apoptosis. The protein levels of Bax and cleaved caspase-3 were decreased and that of Bcl-2 was increased by LPS in HCC cells, which could be rescued by RTF. RTF significantly inhibited the LPS-induced expression of the proinflammatory mediators IL-6 and IL-8 in HCC cells. Mechanistically, with RTF treatment, the upregulated expression of TLR4 and COX-2 induced by LPS was obviously downregulated. Furthermore, the phosphorylation of NF-κB/p65 was significantly decreased in LPS-stimulated cells after supplementation with RTF. Our study suggests that RTF exerts a significant inhibitory effect on the LPS-induced enhancement of the malignant behaviors of HCC cells via inactivation of TLR4/NF-κB signaling. RTF may be a promising chemotherapeutic agent to limit HCC development and inflammation-mediated metastasis.

Paeonol attenuates inflammation by confining HMGB1 to the nucleus

Inflammation is a biological process that exists in a large number of diseases. If the magnitude or duration of inflammation becomes uncontrolled, inflammation may cause pathological damage to the host. HMGB1 and NF-κB have been shown to play pivotal roles in inflammation-related diseases. New drugs aimed at inhibiting HMGB1 expression have become a key research focus. In the present study, we showed that paeonol (Pae), the main active component of Paeonia suffruticosa, decreases the expression of inflammatory cytokines and inhibits the translocation of HMGB1 induced by lipopolysaccharide (LPS). By constructing HMGB1-overexpressing (HMGB1⁺ ) and HMGB1-mutant (HMGB1^m ) RAW264.7 cells, we found that the nuclear HMGB1 could induce an LPS-tolerant state in RAW264.7 cells and that paeonol had no influence on the expression of inflammatory cytokines in HMGB1^m RAW264.7 cells. In addition, the anti-inflammatory property of paeonol was lost in HMGB1 conditional knockout mice, indicating that HMGB1 is a target of paeonol and a mediator through which paeonol exerts its anti-inflammatory function. Additionally, we also found that HMGB1 and P50 competitively bound with P65, thus inactivating the NF-κB pathway. Our research confirmed the anti-inflammation property of paeonol and suggests that inhibiting the translocation of HMGB1 could be a new strategy for treating inflammation.

Artemisinin inhibits TLR4 signaling by targeting co-receptor MD2 in microglial BV-2 cells and prevents lipopolysaccharide-induced blood-brain barrier leakage in mice

Artemisinin and its derivatives have been the frontline drugs for treating malaria. In addition to the antiparasitic effect, accumulating evidence shows that artemisinins can alleviate neuroinflammatory responses in the central nervous system (CNS). However, the precise mechanisms underlying their anti-neuroinflammatory effects are unclear. Herein we attempted to delineate the molecule target of artemisinin in microglia. In vitro protein intrinsic fluorescence titrations and saturation transfer difference (STD)-NMR showed the direct binding of artemisinin to Toll-like receptor TLR4 co-receptor MD2. Cellular thermal shift assay (CETSA) showed that artemisinin binding increased MD2 stability, which implies that artemisinin directly binds to MD2 in the cellular context. Artemisinin bound MD2 showed much less collapse during the molecular dynamic simulations, which supports the increased stability of MD2 upon artemisinin binding. Flow cytometry analysis showed artemisinin inhibited LPS-induced TLR4 dimerization and endocytosis in microglial BV-2 cells. Therefore, artemisinin was found to inhibit the TLR4-JNK signaling axis and block LPS-induced pro-inflammatory factors nitric oxide, IL-1β and TNF-α in BV-2 cells. Furthermore, artemisinin restored LPS-induced decrease of junction proteins ZO-1, Occludin and Claudin-5 in primary brain microvessel endothelial cells, and attenuated LPS-induced blood-brain barrier disruption in mice as assessed by Evans blue. In all, this study unambiguously adds MD2 as a direct binding target of artemisinin in its anti-neuroinflammatory function. The results also suggest that artemisinin could be repurposed as a potential therapeutic intervention for inflammatory CNS diseases.

Determination of Polyphenols in Ilex kudingcha and Insect Tea (Leaves Altered by Animals) by Ultra-high-performance Liquid Chromatography-Triple Quadrupole Mass Spectrometry (UHPLC-QqQ-MS) and Comparison of Their Anti-Aging Effects

Ilex kudingcha C.J. Tseng tea and insect tea, as traditional Chinese teas, are favored for their original craftsmanship, unique flavor, and biological functionality. In this study, ultra high-performance liquid chromatography-triple quadrupole mass spectrometry (UHPLC-QqQ-MS) was used to analyze the bioactive components of the extracts of Ilex kudingcha and insect tea, and D-galactose-induced aging mice were used to compare the in vivo anti-aging effects of Ilex kudingcha and insect tea extracts. The results were remarkable, UHPLC-QqQ-MS analysis showed that ITP contains 29 ingredients, while IKDCP contains 26 ingredients. However, due to the large differences in the content of the main chemical components in IKDCP and ITP, the effects are equally different. At the same time, the in vivo research results suggesting that the anti-aging effects of IKDCP and ITP (500 mg/kg) include the regulation of viscera indices of major organs; improvement in liver, skin, and spleen tissue morphology; decreased production of inflammatory cytokines; up regulation of SOD, CAT, GSH, GSH-PX, and T-AOC and down regulation of NO and MDA levels in serum and liver tissue; reductions in the concentration of pro-inflammatory factors, and increases in the concentration of anti-inflammatory factor. RT-qPCR and western blot assay also showed that IKDCP and ITP affect anti-aging by regulating the gene and protein expression of GSH-PX, GSH1, SOD1, SOD2, and CAT. The overall results indicate that ITP is more effective in treating oxidative damage in aging mice induced by D-galactose. Thus, ITP appears to be an effective functional drink owing to its rich nutritional components and anti-aging activities.

PKM2 Aggravates Cerebral Ischemia Reperfusion-Induced Neuroinflammation via TLR4/MyD88/TRAF6 Signaling Pathway

OBJECTIVES

Cerebral ischemia-reperfusion (I/R) injury is the leading cause of ischemic stroke. Pyruvate Kinase isozymes M2 (PKM2), as a critical glycolytic enzyme during glycolysis, is involved in neuronal apoptosis in rats with hypoxic-ischemic encephalopathy. This study focused on functional investigation and potential molecular mechanism toward PKM2 in cerebral I/R injury.

METHODS

Cerebral I/R injury model was established by middle cerebral artery occlusion (MCAO) in vivo or oxygen-glucose deprivation and reoxygenation (OGD/R) in vitro. qRT-PCR and Western blot were used to detect the expression of PKM2 in I/R injury models. The effects of PKM2 on I/R injury were determined via triphenyl tetrazolium chloride staining and evaluation of neurological deficits. Cell Counting Kit-8 was employed to detect cell viability, and ELISA was conducted to detect pro-inflammatory cytokines. The underlying mechanism involved in regulation of PKM2 on I/R injury was investigated via ELISA and Western blot.

RESULTS

PKM2 was upregulated after cerebral I/R injury. Knockdown of PKM2 alleviated MCAO-induced infarction and neurological dysfunction. Moreover, PKM2 knockdown also alleviated OGD/R-induced neuronal cell injury and inflammatory response. Mechanistically, PKM2 knockdown-induced neuroprotection was accompanied by inhibition of high-mobility group box 1 (HMGB1), reflected by inactivation of TLR4/MyD88 (myeloid differentiation factor 88)/TRAF6 (TNF receptor-associated factor 6) signaling pathway.

CONCLUSIONS

Knockdown of PKM2 attenuated cerebral I/R injury through HMGB1-mediated TLR4/MyD88/TRAF6 expression change, providing a potential target for cerebral I/R injury treatment.

The pathogenic potential of the combined action of chronic Opisthorchis felineus infection and repeated social defeat stress in C57BL/6 mice

Parasitic food-borne diseases and chronic social stress are frequent attributes of day-to-day human life. Therefore, our aim was to model the combined action of chronic Opisthorchis felineus infection and repeated social defeat stress in C57BL/6 mice. Histological examination of the liver revealed inflammation sites, pronounced periductal fibrosis, and cholangiofibrosis together with proliferation of bile ducts and hepatocyte dystrophy in the infected mice, especially in the stress-exposed ones. Simultaneously with liver pathology, we detected significant structural changes in the cerebral cortex. Immunohistochemical analysis of the hippocampus indicated the highest increase in numerical density of Iba 1-, IL-6-, iNOS-, and Arg1-positive cells in mice simultaneously subjected to the two adverse factors. The number of GFAP-positive cells rose during repeated social defeat stress, most strongly in the mice subjected to both infection and stress. Real-time PCR analysis showed that the expression of genes Aif1 and Il6 differed among the analysed brain regions (hippocampus, hypothalamus, and frontal cortex) and depended on the adverse factors applied. In addition, among the brain regions, there was no consistent increase or decrease in these parameters when the two adverse treatments were combined: (i) in the hippocampus, there was upregulation of Aif1 and no change in Il6 expression; (ii) in the hypothalamus, expression levels of Aif1 and Il6 were not different from controls; and (iii) in the frontal cortex, Aif1 expression did not change while Il6 expression increased. It can be concluded that a combination of two long-lasting adverse factors, O. felineus infection and repeated social defeat stress, worsens not only the hepatic but also brain state, as evidenced behaviorally by disturbances of the startle response in mice.

High Mobility Group Box-1 and Blood-Brain Barrier Disruption

Increasing evidence suggests that inflammatory responses are involved in the progression of brain injuries induced by a diverse range of insults, including ischemia, hemorrhage, trauma, epilepsy, and degenerative diseases. During the processes of inflammation, disruption of the blood–brain barrier (BBB) may play a critical role in the enhancement of inflammatory responses and may initiate brain damage because the BBB constitutes an interface between the brain parenchyma and the bloodstream containing blood cells and plasma. The BBB has a distinct structure compared with those in peripheral tissues: it is composed of vascular endothelial cells with tight junctions, numerous pericytes surrounding endothelial cells, astrocytic endfeet, and a basement membrane structure. Under physiological conditions, the BBB should function as an important element in the neurovascular unit (NVU). High mobility group box-1 (HMGB1), a nonhistone nuclear protein, is ubiquitously expressed in almost all kinds of cells. HMGB1 plays important roles in the maintenance of chromatin structure, the regulation of transcription activity, and DNA repair in nuclei. On the other hand, HMGB1 is considered to be a representative damage-associated molecular pattern (DAMP) because it is translocated and released extracellularly from different types of brain cells, including neurons and glia, contributing to the pathophysiology of many diseases in the central nervous system (CNS). The regulation of HMGB1 release or the neutralization of extracellular HMGB1 produces beneficial effects on brain injuries induced by ischemia, hemorrhage, trauma, epilepsy, and Alzheimer’s amyloidpathy in animal models and is associated with improvement of the neurological symptoms. In the present review, we focus on the dynamics of HMGB1 translocation in different disease conditions in the CNS and discuss the functional roles of extracellular HMGB1 in BBB disruption and brain inflammation. There might be common as well as distinct inflammatory processes for each CNS disease. This review will provide novel insights toward an improved understanding of a common pathophysiological process of CNS diseases, namely, BBB disruption mediated by HMGB1. It is proposed that HMGB1 might be an excellent target for the treatment of CNS diseases with BBB disruption.

Neuroinflammation Mechanisms and Phytotherapeutic Intervention: A Systematic Review

Neuroinflammation is indicated in the pathogenesis of several acute and chronic neurological disorders. Acute lesions in the brain parenchyma induce intense and highly complex neuroinflammatory reactions with similar mechanisms among various disease prototypes. Microglial cells in the CNS sense tissue damage and initiate inflammatory responses. The cellular and humoral constituents of the neuroinflammatory reaction to brain injury contribute significantly to secondary brain damage and neurodegeneration. Inflammatory cascades such as proinflammatory cytokines from invading leukocytes and direct cell-mediated cytotoxicity between lymphocytes and neurons are known to cause "collateral damage" in models of acute brain injury. In addition to degeneration and neuronal cell loss, there are secondary inflammatory mechanisms that modulate neuronal activity and affect neuroinflammation which can even be detected at the behavioral level. Hence, several of health conditions result from these pathogenetic conditions which are underlined by progressive neuronal function loss due to chronic inflammation and oxidative stress. In the first part of this Review, we discuss critical neuroinflammatory mediators and their pathways in detail. In the second part, we review the phytochemicals which are considered as potential therapeutic molecules for treating neurodegenerative diseases with an inflammatory component.

Cell Clearing Systems as Targets of Polyphenols in Viral Infections: Potential Implications for COVID-19 Pathogenesis

The novel coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has generated the ongoing coronavirus disease-2019 (COVID-19) pandemic, still with an uncertain outcome. Besides pneumonia and acute lung injury (ALI) or acute respiratory distress syndrome (ARDS), other features became evident in the context of COVID-19. These includes endothelial and coagulation dysfunction with disseminated intravascular coagulation (DIC), and multiple organ dysfunction syndrome (MODS), along with the occurrence of neurological alterations. The multi-system nature of such viral infection is a witness to the exploitation and impairment of ubiquitous subcellular and metabolic pathways for the sake of its life-cycle, ranging from host cell invasion, replication, transmission, up to a cytopathic effect and overt systemic inflammation. In this frame, alterations in cell-clearing systems of the host are emerging as a hallmark in the pathogenesis of various respiratory viruses, including SARS-CoV-2. Indeed, exploitation of the autophagy and proteasome pathways might contribute not only to the replication of the virus at the site of infection but also to the spreading of either mature virions or inflammatory mediators at both cellular and multisystem levels. In this frame, besides a pharmacological therapy, many researchers are wondering if some non-pharmacological substances might counteract or positively modulate the course of the infection. The pharmacological properties of natural compounds have gained increasing attention in the field of alternative and adjunct therapeutic approaches to several diseases. In particular, several naturally-occurring herbal compounds (mostly polyphenols) are reported to produce widespread antiviral, anti-inflammatory, and anti-oxidant effects while acting as autophagy and (immuno)-proteasome modulators. This article attempts to bridge the perturbation of autophagy and proteasome pathways with the potentially beneficial effects of specific phytochemicals and flavonoids in viral infections, with a focus on the multisystem SARS-CoV-2 infection.

Protective Effects of Two Safflower Derived Compounds, Kaempferol and Hydroxysafflor Yellow A, on Hyperglycaemic Stress-Induced Podocyte Apoptosis via Modulating of Macrophage M1/M2 Polarization

Objective

The primary initiating mechanism in diabetes nephropathy (DN) is hyperglycemia-induced inflammation in which macrophage and podocyte play important roles. The present research is aimed at exploring the effects of kaempferol (Ka) and hydroxysafflor yellow A (HSYA) on classically activated (M1)/alternatively activated (M2) macrophage polarization and podocyte apoptosis under hyperglycaemic conditions in vitro.

Methods

(1) RAW264.7 cells were treated with 11.1 mM glucose (NG), 33.3 mM glucose (HG), Ka 4-8 μM, and HSYA 100-200 μM separately. The expressions of inducible nitric oxide synthase (iNOS), tumor necrosis factor- (TNF-) α, mannose receptor (CD206), and arginase- (Arg-) 1 were quantified by Western blotting and real-time quantitative PCR. The collected supernatants from macrophage were named as (NG) MS, (HG) MS, (Ka) MS, and (HSYA) MS. (2) The podocyte survival rate was assessed by Bromodeoxyuridine assay, while TNF-α and interleukin- (IL-) 1β levels were evaluated by Elisa.

Results

(1) Compared to the HG group, the Ka and HSYA 100 μM groups decreased iNOS and TNF-α levels and increased Arg-1 and CD206 expressions significantly (protein and mRNA: p < 0.05, respectively). (2) The podocyte survival rate of Ka 8 μM was higher than that of HG, and the rates of (Ka) MS and (HSYA 100 μM) MS were higher than that of (HG) MS significantly (all: p < 0.05). (3) TNF-α and IL-1β levels of Ka and HSYA 100 μM were significantly lower than those of the HG group, and both levels in the (Ka) MS and (HSYA) MS were lower than those in the (HG) MS group significantly (p < 0.05, respectively).

Conclusion

The protective effects of Ka and HSYA on podocyte apoptosis under hyperglycemic stress are related to their modulation on M1/M2 polarization and the lowering effects on TNF-α and IL-1β levels.

Repairing blood-CNS barriers: Future therapeutic approaches for neuropsychiatric disorders

Central nervous system (CNS) drug development faces significant difficulties that translate into high rates of failure and lack of innovation. The pathophysiology of neurological and psychiatric disorders often results in the breakdown of blood-CNS barriers, disturbing the CNS microenvironment and worsening disease progression. Therefore, restoring the integrity of blood-CNS barriers may have a beneficial influence in several CNS disorders and improve treatment outcomes. In this review, pathways that may be modulated to protect blood-CNS barriers from neuroinflammatory and oxidative insults are featured. First, the participation of the brain endothelium and glial cells in disruption processes is discussed. Then, the relevance of regulatory systems is analysed, specifically the hypothalamic-pituitary axis, the renin-angiotensin system, sleep and circadian rhythms, and glutamate neurotransmission. Lastly, compounds of endogenous and exogenous origin that are known to mediate the repair of blood-CNS barriers are presented. We believe that enhancing the protection of blood-CNS barriers is a promising therapeutic strategy to pursue in the future.

Amburana cearensis: Pharmacological and Neuroprotective Effects of Its Compounds

Amburana cearensis A.C. Smith is an endemic tree from Northeastern Brazil used in folk medicine as teas, decocts and syrups for the treatment of various respiratory and inflammatory diseases, since therapeutic properties have been attributed to compounds from its stem bark and seeds. Numerous pharmacological properties of semi-purified extracts and isolated compounds from A. cearensis have been described in several biological systems, ranging from antimicrobial to anti-inflammatory effects. Some of these activities are attributed to coumarins and phenolic compounds, the major compounds present in A. cearensis seed extracts. Multiple lines of research demonstrate these compounds reduce oxidative stress, inflammation and neuronal death induced by glutamate excitotoxicity, events central to most neuropathologies, including Alzheimer’s disease (AD) and Parkinson’s Disease (PD). This review focuses on the botanical aspects, folk medicine use, biological effects and pharmacological activities of A. cearensis compounds and their potential as novel non-toxic drugs for the treatment of neurodegenerative diseases.

Immunological Significance of HMGB1 Post-Translational Modification and Redox Biology

Most extracellular proteins are secreted via the classical endoplasmic reticulum (ER)/Golgi-dependent secretion pathway; however, some proteins, including a few danger-associated molecular patterns (DAMPs), are secreted via non-classical ER/Golgi-independent secretion pathways. The evolutionarily conserved high mobility group box1 (HMGB1) is a ubiquitous nuclear protein that can be released by almost all cell types. HMGB1 lacks signal peptide and utilizes diverse non-canonical secretion mechanisms for its extracellular export. Although the post-translational modifications of HMGB1 were demonstrated, the oxidation of HMGB1 and secretion mechanisms are not highlighted yet. We currently investigated that peroxiredoxins I and II (PrxI/II) induce the intramolecular disulfide bond formation of HMGB1 in the nucleus. Disulfide HMGB1 is preferentially transported out of the nucleus by binding to the nuclear exportin chromosome-region maintenance 1 (CRM1). We determined the kinetics of HMGB1 oxidation in bone marrow-derived macrophage as early as a few minutes after lipopolysaccharide treatment, peaking at 4 h while disulfide HMGB1 accumulation was observed within the cells, starting to secrete in the late time point. We have shown that HMGB1 oxidation status, which is known to determine the biological activity in extracellular HMGB1, is crucial for the secretion of HMGB1 from the nucleus. This review summarizes selected aspects of HMGB1 redox biology relevant to the induction and propagation of inflammatory diseases. We implicate the immunological significance and the need for novel HMGB1 inhibitors through mechanism-based studies.

Arctigenin exhibits hepatoprotective activity in Toxoplasma gondii-infected host through HMGB1/TLR4/NF-κB pathway

Toxoplasmosis is a parasitic zoonosis with the highest incidence in humans. Severe lesions due to acute toxoplasmosis have been recorded in the visceral organs including the liver, where hepatocytes and Kupffer cells are important innate immune cells. Arctigenin (AG) is a bioactive ingredient of Arctium lappa L. and increasing evidence suggests that AG exhibits anti-oxidant, anti-inflammatory and anti-Toxoplasma gondii (T. gondii) effects. However, the role of AG in acute liver damage induced by T. gondii infection remains unclear. In this study, we analyzed the effects of AG against T. gondii-induced liver damage by establishing an in vitro infection model using a murine liver cell line (NCTC-1469 cells) and an in vivo mouse model with acute T. gondii infection of virulent RH strain. In the current study, AG effectively attenuated hepatocytes apoptosis and inhibited the reproduction of T. gondii. The results of in vitro and in vivo studies showed that AG significantly reduced alanine aminotransferase/aspartate aminotransferase activities and lessened pathological damage of liver. Moreover, AG suppressed T. gondii-induced inducible nitric oxide synthase production. AG also attenuated liver inflammation by inhibiting T. gondii-induced activation of the high-mobility group box1/toll-like receptor 4/nuclear factor-kappa B (HMGB1/TLR4/NF-κB) signaling pathway. These findings demonstrated that AG exhibited prominent hepatoprotective activities in toxoplasmic liver injury with anti-inflammatory effects by inhibiting the HMGB1/TLR4/NF-κB signaling axis. Thus, this study provides the basis for the development of new drugs to treat toxoplasmic hepatitis.

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.

Dynamic Alterations of Brain Injury, Functional Recovery, and Metabolites Profile after Cerebral Ischemia/Reperfusion in Rats Contributes to Potential Biomarkers

Cerebral ischemia-reperfusion (I/R) is characterized by initial transient cerebral ischemia followed by reperfusion. Various pathophysiological processes are involved in brain injury and functional recovery during cerebral I/R. There are few studies on dynamic metabolic process after cerebral I/R. The present study was to observe dynamic alteration of brain injury, functional recovery, and metabolites after cerebral I/R in rats and discover potential metabolic markers. The cerebral I/R model was established by middle cerebral artery occlusion (MCAO) for 90 min, following reperfusion in rats. The results of cerebral infarction area, cerebral edema, and behavior test showed that there were dynamic changes in brain injury and functional recovery at different periods after cerebral I/R. Further analysis showed that the brain injury was severe on the first day of cerebral I/R, and there was a significant functional recovery from the 7th day of cerebral I/R, followed by an aggravation trend of brain injury from the days 7 to 28. Furthermore, Matrix-assisted laser desorption ionization mass spectrometry imaging analysis showed that the expression of ATP, glucose, and citric acid on 7th day was the highest during cerebral I/R, which indicated that energy metabolism and oxidative phosphorylation played important roles during cerebral I/R. In addition, the untargeted metabolomic results showed that the level of isocitric acid, the ratio of oxyglutaric acid/glutamic acid, and the level of pyruvic acid associated with the TCA cycle were also the highest on the 7th day during cerebral I/R, which indicated that the transient spontaneous recovery of ischemic brain on the 7th day after ischemia-reperfusion might be related to oxidative phosphorylation and energy metabolism in the brain in this period. In conclusion, the results suggest that some small molecule metabolites participate in the brain injury and functional recovery during cerebral I/R, which is of great significance to the development of therapeutic drugs and diagnostic markers.

MG53 attenuates lipopolysaccharide-induced neurotoxicity and neuroinflammation via inhibiting TLR4/NF-κB pathway in vitro and in vivo

Neuroinflammation plays important roles in the pathogenesis and development of neurodegenerative disorders. Lipopolysaccharide (LPS) induces neuroinflammation and causes neurotoxicity, which results in cell damage or memory impairment in different cells and animals. In the present study, we investigated the neuroprotective effects of MG53, a member of the TRIM family proteins, against LPS-induced neuroinflammation and neurotoxicity in vitro and in vivo. MG53 significantly protected HT22 cells against LPS-induced cell apoptosis and cell cycle arrest by inhibiting TNF-α, IL-6 and IL-1β expression. In addition, MG53 ameliorated LPS-induced memory impairment and neuronal cell death in mice. Interestingly, MG53 significantly promoted newborn cell survival, improved neurogenesis, and mitigated neuroinflammation evidenced by lower production of IL-1β and IL-6, less activation of microglia in the hippocampus of LPS treated mice. Further studies demonstrated that MG53 significantly inhibited TLR4 expression and nuclear factor-κB (NF-κB) phosphorylation in LPS treated HT22 cells and mice. Taken together, our results suggested that MG53 attenuated LPS-induced neurotoxicity and neuroinflammation partly by inhibiting TLR4/NF-κB pathway in vitro and in vivo.

Association between fecal microbiota and generalized anxiety disorder: Severity and early treatment response

BACKGROUND

Associations between abnormal gut microbiome compositions and anxiety-like behaviors are well established. However, it is unknown whether the gut microbiome composition is associated with the severity of generalized anxiety disorder (GAD) and relief from clinical symptoms in patients.

METHODS

Stool samples from 36 patients with active GAD (A-GAD group) and 24 matched healthy control subjects (HC group) were analyzed by 16S rRNA gene sequencing. Anxiety was assessed with the Hamilton Anxiety Rating Scale and the Self-rating Anxiety Scale, and global assessments of functioning were performed at baseline and 1 month after drug treatment.

RESULTS

Gut microbiome compositions were altered in A-GAD patients, with fewer operational taxonomic units and lower fecal bacterial α-diversity. Specifically, Firmicutes and Tenericutes abundances were lower in A-GAD patients, and several genera were differentially represented in the A-GAD and HC groups. The abundances of Eubacterium_coprostanoligenes_group, Ruminococcaceae_UCG-014, and Prevotella_9 correlated negatively with the anxiety severity and positively with anxiety reduction, whereas the abundances of Bacteroides and Escherichia-Shigella were positively associated with anxiety severity. Sex, smoking, and alcohol intake influenced the gut microbiome composition.

LIMITATIONS

The sample sizes were small and the stool samples were collected only at baseline; therefore, a causal association between changes in intestinal flora and disease remission was not established. Moreover, the effects of different drugs on gut microbiome composition were not investigated.

CONCLUSIONS

Altered gut microbiome composition may contribute to GAD pathogenesis and remission.

β-Defensin 129 Attenuates Bacterial Endotoxin-Induced Inflammation and Intestinal Epithelial Cell Apoptosis

Defensins have attracted considerable research interest worldwide because of their potential to serve as a substitute for antibiotics. In this study, we characterized a novel porcine β-defensin (pBD129) and explored its role in alleviating bacterial endotoxin-induced inflammation and intestinal epithelium atrophy. The pBD129 gene was cloned and expressed in Escherichia coli. A recombinant pBD129 protein was also purified. To explore its role in alleviating the endotoxin-induced inflammation, mice, with or without lipopolysaccharide (LPS) challenge were treated by pBD129 at different doses. The recombinant pBD129 showed significant antimicrobial activities against the E. coli and Streptococcus with a minimal inhibitory concentration (MICs) of 32 μg/mL. Hemolytic assays showed that the pBD129 had no detrimental impact on cell viabilities. Interestingly, we found that pBD129 attenuated LPS-induced inflammatory responses by decreasing serum concentrations of inflammatory cytokines, such as the IL-1β, IL-6, and TNF-α (P < 0.05). Moreover, pBD129 elevated the intestinal villus height (P < 0.05) and enhanced the expression and localization of the major tight junction-associated protein ZO-1 in LPS-challenged mice. Additionally, pDB129 at a high dose significantly decreased serum diamine oxidase (DAO) concentration (P < 0.05) and reduced intestinal epithelium cell apoptosis (P < 0.05) in LPS-challenged mice. Importantly, pBD129 elevated the expression level of Bcl-2-associated death promoter (Bcl-2), but down-regulated the expression levels of apoptosis-related genes such as the B-cell lymphoma-2-associated X protein (Bax), BH3-interacting domain death agonist (Bid), cysteinyl aspartate-specific proteinase-3 (Caspase-3), and caspase-9 in the intestinal mucosa (P < 0.05). These results suggested a novel function of the mammalian defensins, and the anti-bacterial and anti-inflammatory properties of pBD129 may allow it a potential substitute for conventionally used antibiotics or drugs.

Myricitrin blocks activation of NF-κB and MAPK signaling pathways to protect nigrostriatum neuron in LPS-stimulated mice

Myricitrin, a bioactive and natural flavonoids, is well known for its anti-inflammatory and antioxidant properties. However, the anti-neuroinflammation and possible mechanism has not been fully elucidated. Therefore, the present study was to investigate the possible mechanism of its neuroprotection and anti-neuroinflammation in the nigrostriatum of LPS-stimulated mice. The results showed that myricitrin improved neuron injury and raised the expressions of PSD-95 protein and TH protein in the nigrostriatum of LPS-stimulated mice. In addition, myricitrin decreased the production of pro-inflammatory factors including IL-1β, IL-6 and TNFα, decreased the level of chemokine MCP-1, and suppressed the expressions of COX-2 and iNOS. Meanwhile, myricitrin suppressed HMGB1, TLR4, and MyD88 expression in the nigrostriatum of LPS-stimulated mice. Furthermore, myricitrin inhibited NF-κB and MAPK signaling pathways activated by LPS. In conclusion, our studies suggest that myricitrin blocks activation of protects NF-κB and MAPK signaling pathways to nigrostiatum neuron from injury in LPS-stimulated mice and is beneficial to treatment nigrostriatum inflammation of PD.

Microglia Activated by Excess Cortisol Induce HMGB1 Acetylation and Neuroinflammation in the Hippocampal DG Region of Mice Following Cold Exposure

Cold stress can induce neuroinflammation in the hippocampal dentate gyrus (DG), but the mechanism underlying neuronal apoptosis induced by cold stress is not well-understood. To address this issue, male and female C57BL/6 mice were exposed to a temperature of 4 °C for 3 h per day for 1 week, and glial cell activation, neuronal apoptosis, and neuroinflammation were evaluated by western blotting, immunofluorescence, terminal deoxynucleotidyl transferase 2’-deoxyuridine 5’-triphosphate (dUTP) nick end labeling, Nissl staining, and immunohistochemistry. Additionally, BV2 cells were treated with different concentrations of cortisol (CORT) for 3 h to mimic stress and molecular changes were assessed by western blotting, immunofluorescence, and co-immunoprecipitation. We found that excess CORT activated glial cells and increased neuroinflammation in the DG of mice exposed to cold temperatures, which was associated with increased acetylation and nuclear factor-κB signaling. These effects were mediated by the acetylation of lysine 9 of histone 3 and lysine 310 of p65, which resulted in increased mitogen-activated protein kinase phosphorylation, nuclear translocation of p65, microglia activation, and acetylation of high-mobility group box 1. Neuroinflammation was more severe in male compared to female mice. These findings provide new insight into the mechanisms of the cold stress response, which can inform the development of new strategies to combat the effects of hypothermia.