Up-down regulation of HO-1 and iNOS gene expressions by ethyl pyruvate via recruiting p300 to Nrf2 and depriving It from p65

Moringin alleviates DSS-induced ulcerative colitis in mice by regulating Nrf2/NF-κB pathway and PI3K/AKT/mTOR pathway

Ulcerative colitis (UC) is a main form of inflammatory bowel disease (IBD), which is a chronic and immune-mediated inflammatory disease. Moringin (MOR) is an isothiocyanate isolated from Moringa oleifera Lam., and has been recognized as a promising potent drug for inflammatory diseases and antibacterial infections. The present study investigated the role of moringin in dextran sulfate sodium (DSS)-induced UC mice. Mouse colitis was induced by adding DSS to the drinking water for seven consecutive days. Our experimental results showed that MOR relieves DSS-induced UC in mice by increasing body weight and colonic length, and reducing the disease activity index and histological injury. Mechanistically, MOR improves intestinal barrier function by increasing the expression of tight junction proteins (TJPs) and enhancing the secretion of mucin in DSS-induced mice. MOR inhibits inflammatory response and intestinal damage by regulating Nrf2/NF-κB signaling pathway and modulating the PI3K/AKT/mTOR pathway. Furthermore, in Nrf2 knockout (Nrf2-/-) mice, the protective effects of MOR on DSS-induced UC were abolished. Meanwhile, treatment with MOR reduced inflammation and cell damage via regulating Nrf2/NF-κB pathway in a lipopolysaccharide (LPS)-induced inflammation model of Caco-2 cells. In contrast, ML385, an Nrf2 inhibitor, might eliminate the protection provided by MOR. Notably, treatment with MOR significantly up-regulated the expression of peroxisome proliferator-activated receptor-γ (PPAR-γ), suggesting that MOR may be a potential PPAR-γ activator. In conclusion, MOR exerts protective effect in UC by improving intestinal barrier function, regulating Nrf2/NF-κB and PI3K/AKT/mTOR signaling pathways, and another effect associated with the regulation of PPAR-γ expression.

Cucurbitacin B attenuates osteoarthritis development by inhibiting NLRP3 inflammasome activation and pyroptosis through activating Nrf2/HO-1 pathway

Osteoarthritis (OA) is a complicated joint disorder characterized by inflammation that causes joint destruction. Cucurbitacin B (CuB) is a naturally occurring triterpenoid compound derived from plants in the Cucurbitaceae family. The aim of this study is to investigate the potential role and mechanisms of CuB in a mouse model of OA. This study identified the key targets and potential pathways of CuB through network pharmacology analysis. In vivo and in vitro studies confirmed the potential mechanisms of CuB in OA. Through network pharmacology, 54 potential targets for CuB in treating OA were identified. The therapeutic potential of CuB is associated with the nod-like receptor pyrin domain 3 (NLRP3) inflammasome and pyroptosis. Molecular docking results indicate a strong binding affinity of CuB to nuclear factor erythroid 2-related factor 2 (Nrf2) and p65. In vitro experiments demonstrate that CuB effectively inhibits the expression of pro-inflammatory factors induced by interleukin-1β (IL-1β), including cyclooxygenase-2, inducible nitric oxide synthase, IL-1β, and IL-18. CuB inhibits the degradation of type II collagen and aggrecan in the extracellular matrix (ECM), as well as the expression of matrix metalloproteinase-13 and a disintegrin and metalloproteinase with thrombospondin motifs-5. CuB protects cells by activating the Nrf2/hemeoxygenase-1 (HO-1) pathway and inhibiting nuclear factor-κB (NF-κB)/NLRP3 inflammasome-mediated pyroptosis. Moreover, in vivo experiments show that CuB can slow down cartilage degradation in an OA mouse model. CuB effectively prevents the progression of OA by inhibiting inflammation in chondrocytes and ECM degradation. This action is further mediated through the activation of the Nrf2/HO-1 pathway to inhibit NF-κB/NLRP3 inflammasome activation. Thus, CuB is a potential therapeutic agent for OA.

Human umbilical cord mesenchymal stem cell-derived exosomes attenuate neuroinflammation and oxidative stress through the NRF2/NF-κB/NLRP3 pathway

AIMS

We investigated whether human umbilical cord mesenchymal stem cell (hUC-MSC)-derived exosomes bear therapeutic potential against lipopolysaccharide (LPS)-induced neuroinflammation.

METHODS

Exosomes were isolated from hUC-MSC supernatant by ultra-high-speed centrifugation and characterized by transmission electron microscopy and western blotting. Inflammatory responses were induced by LPS in BV-2 cells, primary microglial cultures, and C57BL/6J mice. H2 O2 was also used to induce inflammation and oxidative stress in BV-2 cells. The effects of hUC-MSC-derived exosomes on inflammatory cytokine expression, oxidative stress, and microglia polarization were studied by immunofluorescence and western blotting.

RESULTS

Treatment with hUC-MSC-derived exosomes significantly decreased the LPS- or H2 O2 -induced oxidative stress and expression of pro-inflammatory cytokines (IL-6 and TNF-α) in vitro, while promoting an anti-inflammatory (classical M2) phenotype in an LPS-treated mouse model. Mechanistically, the exosomes increased the NRF2 levels and inhibited the LPS-induced NF-κB p65 phosphorylation and NLRP3 inflammasome activation. In contrast, the reactive oxygen species scavenger NAC and NF-κB inhibitor BAY 11-7082 also inhibited the LPS-induced NLRP3 inflammasome activation and switched to the classical M2 phenotype. Treatment with the NRF2 inhibitor ML385 abolished the anti-inflammatory and anti-oxidative effects of the exosomes.

CONCLUSION

hUC-MSC-derived exosomes ameliorated LPS/H2 O2 -induced neuroinflammation and oxidative stress by inhibiting the microglial NRF2/NF-κB/NLRP3 signaling pathway.

Advances in developing noncovalent small molecules targeting Keap1

Kelch-like ECH-associated protein 1 (Keap1) is a drug target for diseases involving oxidative stress and inflammation. There are three covalent Keap1-binding drugs on the market, but noncovalent compounds that inhibit the interaction between Keap1 and nuclear factor erythroid 2-related factor 2 (Nrf2) represent an attractive alternative. Both compound types prevent degradation of Nrf2, leading to the expression of antioxidant and antiinflammatory proteins. However, their off-target profiles differ as do their exact pharmacodynamic effects. Here, we discuss the opportunities and challenges of targeting Keap1 with covalent versus noncovalent inhibitors. We then provide a comprehensive overview of current noncovalent Keap1-Nrf2 inhibitors, with a focus on their pharmacological effects, to examine the therapeutic potential for this compound class.

Esculeogenin A, a Glycan from Tomato, Alleviates Nonalcoholic Fatty Liver Disease in Rats through Hypolipidemic, Antioxidant, and Anti-Inflammatory Effects

This study examined the preventative effects of esculeogenin A (ESGA), a newly discovered glycan from tomato, on liver damage and hepatic steatosis in high-fat-diet (HFD)-fed male rats. The animals were divided into six groups (each of eight rats): a control group fed a normal diet, control + ESGA (200 mg/kg), HFD, and HFD + ESAG in 3 doses (50, 100, and 200 mg/kg). Feeding and treatments were conducted for 12 weeks. Treatment with ESGA did not affect gains in the body or fat weight nor increases in fasting glucose, insulin, and HOMA-IR or serum levels of free fatty acids (FFAs), tumor-necrosis factor-α, and interleukin-6 (IL-6). On the contrary, it significantly reduced the serum levels of gamma-glutamyl transpeptidase (GGT), aspartate aminotransferase (AST), alanine aminotransferase (ALT), total triglycerides (TGs), cholesterol (CHOL), and low-density lipoprotein cholesterol (LDL-c) in the HFD-fed rats. In addition, it improved the liver structure, attenuating the increase in fat vacuoles; reduced levels of TGs and CHOL, and the mRNA levels of SREBP1 and acetyl CoA carboxylase (ACC); and upregulated the mRNA levels of proliferator-activated receptor α (PPARα) and carnitine palmitoyltransferase I (CPT I) in HFD-fed rats. These effects were concomitant with increases in the mRNA, cytoplasmic, and nuclear levels of nuclear factor erythroid 2-related factor 2 (Nrf2), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and heme oxygenase-1 (HO); a reduction in the nuclear activity of nuclear factor-kappa beta (NF-κB); and inhibition of the activity of nuclear factor kappa B kinase subunit beta (IKKβ). All of these effects were dose-dependent effects in which a normal liver structure and normal levels of all measured parameters were seen in HFD + ESGA (200 mg/kg)-treated rats. In conclusion, ESGA prevents NAFLD in HFD-fed rats by attenuating hyperlipidemia, hepatic steatosis, oxidative stress, and inflammation by acting locally on Nrf2, NF-κB, SREBP1, and PPARα transcription factors.

Roflumilast attenuates neuroinflammation post retinal ischemia/reperfusion injury by regulating microglia phenotype via the Nrf2/STING/NF-κB pathway

PURPOSE

The abnormal polarisation of microglial cells (MGs) following retinal ischemia/reperfusion (RIR) initiates neuroinflammation and progressive death of retinal ganglion cells (RGCs), causing increasingly severe and irreversible visual dysfunction. Roflumilast (Roflu) is a promising candidate for treating neuroinflammatory diseases. This study aimed to explore whether Roflu displayed a cytoprotective effect against RIR-induced neuroinflammation and to characterise the underlying signalling pathway.

METHODS

The effects and mechanism of Roflu against RIR injury were investigated in C57BL/6J mice and the BV2 cell line. We used quantitative real-time PCR and enzyme-linked immunosorbent assay to examine the levels of inflammatory factors. Furthermore, haematoxylin and eosin and immunofluorescence (IF) stainings were used to assess the morphology of the retina and the states of MGs and RGCs. Reactive oxygen species (ROS) levels were examined using a ROS assay kit, while whole-genome sequencing analysis was conducted to identify altered pathways and molecules. Western blotting and IF staining were used to quantify the proteins associated with the nuclear factor erythroid 2-related factor 2 (Nrf2)/stimulator of interferon gene (STING)/nuclear factor kappa beta (NF-κB) pathway.

RESULTS

MG polarisation includes the pro-inflammatory and neurotoxic M1 phenotype as well as the anti-inflammatory and neuroprotective M2 phenotype. Roflu significantly attenuated MG activation and contributed to a shift in the MG phenotype from M1 to M2. Moreover, Roflu decreased ROS release and increased heme oxygenase 1 and NAD(P)H quinone oxidoreductase 1 expression. In vitro and in vivo experiments validated that Roflu exerted its neuroprotective effects primarily by upregulating the Nrf2/STING/NF-κB pathway. However, these effects were abrogated when the Nrf2 expression was inhibited by pharmacological or genetic manipulation.

CONCLUSIONS

Roflu suppressed RIR-induced neuroinflammation by driving the shift of MG polarisation from M1 to M2 phenotype, which was mediated by the upregulation of the Nrf2/STING/NK-κB pathway.

Scutellarin attenuates oxidative stress and neuroinflammation in cerebral ischemia/reperfusion injury through PI3K/Akt-mediated Nrf2 signaling pathways

Cerebral ischemia/reperfusion injury (CIRI) seriously threatens human life and health. Scutellarin (Scu) exhibits neuroprotective effects, but little is known about its underlying mechanism. Therefore, we explored its protective effect on CIRI and the underlying mechanism. Our results demonstrated that Scu rescued HT22 cells from cytotoxicity induced by oxygen and glucose deprivation/reoxygenation (OGD/R). Scu also showed antioxidant activity by promoting nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear translocation, upregulating heme oxygenase-1 (HO-1) expression, increasing superoxide dismutase (SOD) activity, and inhibiting reactive oxygen species (ROS) generation in vitro. Additionally, Scu reduced nuclear factor-kappa B (NF-κB) activity and the levels of pro-inflammatory factors. Interestingly, these effects were abolished by Nrf2 inhibition. Furthermore, Scu reduced infarct volume and blood-brain barrier (BBB) permeability, improved sensorimotor functions and depressive behaviors, and alleviated oxidative stress and neuroinflammation in rats subjected to middle cerebral artery occlusion/reperfusion (MCAO/R). Mechanistically, Scu-induced Nrf2 nuclear accumulation and inactivation of NF-κB were accompanied by an enhanced level of phosphorylated protein kinase B (p-AKT) both in vitro and in vivo. Pharmacologically inhibiting the phosphatidylinositol-3-kinase/protein kinase B (PI3K/AKT) pathway blocked Scu-induced Nrf2 nuclear translocation and inactivation of NF-κB, as well as its antioxidant and anti-inflammatory activities. In summary, these results suggest that Scu exhibits antioxidant, anti-inflammatory, and neuroprotective effects in CIRI through Nrf2 activation mediated by the PI3K/Akt pathway.

Phillygenin inhibits inflammation in chondrocytes via the Nrf2/NF-κB axis and ameliorates osteoarthritis in mice

Objective

Osteoarthritis (OA), widely seen in the elderly, is featured by cartilage degradation, subchondral bone remolding, and synovium inflammation. Currently, there is no cure for OA development. Phillygenin (PHI), an active ingredient from the Forsythiae Fructus, possesses many biological properties, such as anti-inflammation and anti-oxidative stress in several diseases. However, the potential effects and underlying mechanisms of PHI on OA remain unclear.

Methods

Western blotting, RT-PCR, ELISA and tissue staining were employed to explore the mechanisms by which PHI exerted a protective effect on IL-1β-induced production of pro-inflammation cytokines and extracellular matrix (ECM) degradation in primary murine chondrocytes and destabilization of the medial meniscus (DMM) mouse models.

Results

In this study, we found that PHI inhibited the production of pro-inflammation cytokines and ECM degradation induced by IL-1β in primary murine chondrocytes. Mechanically, PHI inhibited the NF-κB pathway via activating nuclear factor (erythrluteolind-derived 2)-like 2 (Nrf2). In vivo experiments also confirmed the chondroprotection of PHI in DMM mouse models.

Conclusion

PHI alleviated IL-1β-induced inflammation cytokines and ECM degradation via activating Nrf2 and inhibiting NF-κB pathway.

The translational potential of this article

This study provides a biological rationale for the use of PHI as a potential candidate for OA treatment.

Plant-Derived Extracellular Vesicles and Their Exciting Potential as the Future of Next-Generation Drug Delivery

Plant cells release tiny membranous vesicles called extracellular vesicles (EVs), which are rich in lipids, proteins, nucleic acids, and pharmacologically active compounds. These plant-derived EVs (PDEVs) are safe and easily extractable and have been shown to have therapeutic effects against inflammation, cancer, bacteria, and aging. They have shown promise in preventing or treating colitis, cancer, alcoholic liver disease, and even COVID-19. PDEVs can also be used as natural carriers for small-molecule drugs and nucleic acids through various administration routes such as oral, transdermal, or injection. The unique advantages of PDEVs make them highly competitive in clinical applications and preventive healthcare products in the future. This review covers the latest methods for isolating and characterizing PDEVs, their applications in disease prevention and treatment, and their potential as a new drug carrier, with special attention to their commercial viability and toxicological profile, as the future of nanomedicine therapeutics. This review champions the formation of a new task force specializing in PDEVs to address a global need for rigor and standardization in PDEV research.

Inhibition of Microglial GSK3β Activity Is Common to Different Kinds of Antidepressants: A Proposal for an In Vitro Screen to Detect Novel Antidepressant Principles

Depression is a major public health concern. Unfortunately, the present antidepressants often are insufficiently effective, whilst the discovery of more effective antidepressants has been extremely sluggish. The objective of this review was to combine the literature on depression with the pharmacology of antidepressant compounds, in order to formulate a conceivable pathophysiological process, allowing proposals how to accelerate the discovery process. Risk factors for depression initiate an infection-like inflammation in the brain that involves activation microglial Toll-like receptors and glycogen synthase kinase-3β (GSK3β). GSK3β activity alters the balance between two competing transcription factors, the pro-inflammatory/pro-oxidative transcription factor NFκB and the neuroprotective, anti-inflammatory and anti-oxidative transcription factor NRF2. The antidepressant activity of tricyclic antidepressants is assumed to involve activation of GS-coupled microglial receptors, raising intracellular cAMP levels and activation of protein kinase A (PKA). PKA and similar kinases inhibit the enzyme activity of GSK3β. Experimental antidepressant principles, including cannabinoid receptor-2 activation, opioid μ receptor agonists, 5HT2 agonists, valproate, ketamine and electrical stimulation of the Vagus nerve, all activate microglial pathways that result in GSK3β-inhibition. An in vitro screen for NRF2-activation in microglial cells with TLR-activated GSK3β activity, might therefore lead to the detection of totally novel antidepressant principles with, hopefully, an improved therapeutic efficacy.

Nrf2 Regulates the Expression of CYP2D6 by Inhibiting the Activity of Krüppel-Like Factor 9 (KLF9)

AIMS

The aim of the present study is to gain insight into the biology of Parkinson's disease (PD) and cancer to drive translational advances enabling more effective prevention and/or potential treatments.

BACKGROUND

The expression of Cytochrome P450 2D6 (CYP2D6) is correlated with various diseases such as PD and cancer; therefore, exploring its regulatory mechanism at transcriptional levels is of interest. NF-E2-related factor 2 (Nrf2) has been known to be responsible for regulating phase II and phase III drug-metabolizing genes.

OBJECTIVES

The objectives of this study are to investigate the transcriptional regulation of CYP2D6 by Nrf2 and to analyze its role in PD and cancer.

METHODS

Nrf2 was transiently expressed in human hepatoma Hep3B cells, and the expression of CYP2D6 was examined by RT-qPCR. The promoter activity of CYP2D6 and the DNA binding of Nrf2 were examined by luciferase and ChIP assay, respectively. We then investigated the expression and correlation of Nrf2 and CYP2D6 in the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) datasets.

RESULTS

In the present study, we demonstrated that Nrf2 down-regulated CYP2D6 mRNA expression in hepatoma Hep3B cells. Mechanistically, Nrf2 binds to the antioxidant responsive element (ARE) in the proximity of krüppel- like factor 9 (KLF9)-binding site within the -550/+51 of CYP2D6 promoter. The inhibition and activation of Nrf2 enhanced and suppressed KLF9 effects on CYP2D6 expression, respectively. The expression levels of Nrf2 and CYP2D6 were upregulated and downregulated in the PD patient GEO datasets compared to the healthy control tissues, and Nrf2 was negatively correlated with CYP2D6. In liver cancer patients, decreased CYP2D6 levels were apparent and associated with a lower probability of survival.

CONCLUSION

Our work revealed the inhibitory role of Nrf2 in regulating CYP2D6 expression. Moreover, Nrf2- dependent regulation of CYP2D6 can be used as a prognostic factor and therapeutic strategy in PD and liver cancer.

BP5 alleviates endotoxemia-induced acute lung injury by activating Nrf2 via dual regulation of the Keap1-Nrf2 interaction and the Akt (Ser473)/GSK3β (Ser9)/Fyn pathway

Oxidative stress and inflammation play a crucial role in the pathogenesis of acute lung injury (ALI). Previously, pentapeptide bursopentin (BP5, Cys-Lys-Arg-Val-Tyr) was reported to possess significant antioxidant activity and inhibit lipopolysaccharides (LPS)-induced NF-κB activation in vitro, whereas little is known about its effects in vivo. In this study, we explored the effects of BP5 on endotoxemia-induced ALI in mice and the underlying molecular mechanisms. Our studies revealed that BP5 markedly improved survival and effectively alleviated lung injury by reducing overoxidation and excessive inflammatory response in endotoxemia mice. In LPS-stimulated mouse primary macrophages and RAW 264.7 cells, BP5 also exhibited antioxidant and anti-inflammatory properties by enhancing Nrf2 activation. Importantly, these beneficial effects were abolished by Nrf2 knockdown. To further elucidate the underlying mechanisms, we performed localized surface plasmon resonance (LSPR) assays, molecular docking, together with cell-based studies, and found that BP5 inhibited the Keap1-Nrf2 interaction to promote Nrf2 nuclear translocation and activation. Moreover, BP5-induced Nrf2 activation was shown to be accompanied by an increase in the phosphorylation of Akt (at Ser473) and GSK3β (at Ser9), and a decrease in Fyn nuclear accumulation both in vitro and in vivo. Pharmacologically inhibiting phosphorylation of Akt and GSK3β obviously enhanced Fyn nuclear accumulation in RAW 264.7 cells, which partially attenuated the promoting effect of BP5 on Nrf2 nuclear accumulation and activation. Furthermore, In Nrf2^-/- mice, the protective effects of BP5 on the endotoxemia-induced ALI in WT mice were largely vanished. Our findings indicated that BP5 effectively protected endotoxemia-induced ALI against oxidative stress and inflammatory response, which are largely dependent on activation of the Nrf2 pathway. Underlying mechanisms include dual regulation of the Keap-Nrf2 interaction and the Akt (Ser473)/GSK3β (Ser9)/Fyn pathway.

The molecular activity of cannabidiol in the regulation of Nrf2 system interacting with NF-κB pathway under oxidative stress

Cannabidiol (CBD), the major non-psychoactive phytocannabinoid of Cannabis sativa L., is one of the most studied compounds in pharmacotherapeutic approaches to treat oxidative stress-related diseases such as cardiovascular, metabolic, neurodegenerative, and neoplastic diseases. The literature data to date indicate the possibility of both antioxidant and pro-oxidative effects of CBD. Thus, the mechanism of action of this natural compound in the regulation of nuclear factor 2 associated with erythroid 2 (Nrf2), which plays the role of the main cytoprotective regulator of redox balance and inflammation under oxidative stress conditions, seems to be particularly important. Moreover, Nrf2 is strongly correlated with the cellular neoplastic profile and malignancy, which in turn is critical in determining the cellular response induced by CBD under pathophysiological conditions. This paper summarizes the CBD-mediated pathways of regulation of the Nrf2 system by altering the expression and modification of both proteins directly involved in Nrf2 transcriptional activity and proteins involved in the relationship between Nrf2 and the nuclear factor kappa B (NF-κB) which is another redox-sensitive transcription factor.

Microglia-mediated neuroinflammation and neuroplasticity after stroke

Stroke remains a major cause of long-term disability and mortality worldwide. The immune system plays an important role in determining the condition of the brain following stroke. As the resident innate immune cells of the central nervous system, microglia are the primary responders in a defense network covering the entire brain parenchyma, and exert various functions depending on dynamic communications with neurons, astrocytes, and other neighboring cells under both physiological or pathological conditions. Microglia activation and polarization is crucial for brain damage and repair following ischemic stroke, and is considered a double-edged sword for neurological recovery. Microglia can exist in pro-inflammatory states and promote secondary brain damage, but they can also secrete anti-inflammatory cytokines and neurotrophic factors and facilitate recovery following stroke. In this review, we focus on the role and mechanisms of microglia-mediated neuroinflammation and neuroplasticity after ischemia and relevant potential microglia-based interventions for stroke therapy.

Mapping the dynamics of Nrf2 antioxidant and NFκB inflammatory responses by soft electrophilic chemicals in human liver cells defines the transition from adaptive to adverse responses

A comprehensive understanding of the dynamic activation and crosstalk between different cellular stress response pathways that drive cell adversity is crucial in chemical safety assessment. Various chemicals have electrophilic properties that drive cell injury responses in particular oxidative stress signaling and inflammatory signaling. Here we used bacterial artificial chromosome-based GFP cellular stress reporters with live cell confocal imaging, to systematically monitor the differential modulation of the dynamics of stress pathway activation by six different soft electrophiles: sulforaphane, andrographolide, diethyl maleate, CDDO-Me, ethacrynic acid and tert-butyl hydroquinone. The various soft electrophiles showed differential potency and dynamics of Nrf2 activation and nuclear translocation. These differences in Nrf2 dynamics correlated with distinct activation pattern of Nrf2 downstream targets SRNX1 and HMOX1. All soft electrophiles caused a strong dose dependent suppression of a cytokine-induced NFĸB response represented by suppression of NFĸB nuclear oscillation and inhibition of the downstream target gene activation A20 and ICAM1, which followed the potency of Nrf2 modulation but occurred at higher concentration close to saturation of Nrf2 activation. RNAi-based depletion of RelA resulted in a prolonged presence of Nrf2 in the nucleus after soft electrophile treatment; depletion of Nrf2 caused the induction of NFĸB signaling and activation of its downstream targets A20 and ICAM1. A systematic transcriptome analysis confirmed these effects by soft electrophiles on Nrf2 and NFκB signaling crosstalk in human induced-pluripotent stem cell-derived hepatocyte-like cells. Altogether our data indicate that modulation of Nrf2 by soft electrophiles may have consequences for efficient inflammatory signaling.

Focusing on Future Applications and Current Challenges of Plant Derived Extracellular Vesicles

Plant derived extracellular vesicles (EVs) are nano-sized membranous vesicles released by plant cells, which contain lipids, proteins, nucleic acids and specific pharmacologically active substances. They are safe, widely available and expediently extractive. They have gratifyingly biological activity against inflammation, cancer, bacteria and oxidative aging, especially for the prevention or treatment of colitis, cancer, alcoholic liver, and COVID-19. In addition, as natural drug carriers, plant derived EVs have the potential to target the delivery of small molecule drugs and nucleic acid through oral, transdermal, injection. With the above advantages, plant derived EVs are expected to have excellent strong competitiveness in clinical application or preventive health care products in the future. We comprehensively reviewed the latest separation methods and physical characterization techniques of plant derived EVs, summarized the application of them in disease prevention or treatment and as a new drug carrier, and analyzed the clinical application prospect of plant derived EVs as a new drug carrier in the future. Finally, the problems hindering the development of plant derived EVs at present and consideration of the standardized application of them are discussed.

Dissecting the Crosstalk Between Nrf2 and NF-κB Response Pathways in Drug-Induced Toxicity

Nrf2 and NF-κB are important regulators of the response to oxidative stress and inflammation in the body. Previous pharmacological and genetic studies have confirmed crosstalk between the two. The deficiency of Nrf2 elevates the expression of NF-κB, leading to increased production of inflammatory factors, while NF-κB can affect the expression of downstream target genes by regulating the transcription and activity of Nrf2. At the same time, many therapeutic drug-induced organ toxicities, including hepatotoxicity, nephrotoxicity, cardiotoxicity, pulmonary toxicity, dermal toxicity, and neurotoxicity, have received increasing attention from researchers in clinical practice. Drug-induced organ injury can destroy body function, reduce the patients’ quality of life, and even threaten the lives of patients. Therefore, it is urgent to find protective drugs to ameliorate drug-induced injury. There is substantial evidence that protective medications can alleviate drug-induced organ toxicity by modulating both Nrf2 and NF-κB signaling pathways. Thus, it has become increasingly important to explore the crosstalk mechanism between Nrf2 and NF-κB in drug-induced toxicity. In this review, we summarize the potential molecular mechanisms of Nrf2 and NF-κB pathways and the important effects on adverse effects including toxic reactions and look forward to finding protective drugs that can target the crosstalk between the two.

Nrf2/ARE axis signalling in hepatocyte cellular death

The Nrf2-ARE transcriptional pathway plays an important role amongst cellular defence systems regulating and ensuring adequacy of redox responses and oxidant signalling factors. Hepatocyte cellular death and injury is a prominent feature underlying liver pathologies. Diverse endogenous molecules and targets contribute to the outcome of cell survival and the consequent mode of cell death. Several research efforts focused on the confirmation of Nrf2 presence in cell death and its vital necessity against cell compromise, however, little they comprehend of such participation. Hepatocyte cell death modes discussed in this review including autophagy, apoptosis, necrosis, ferroptosis, pyroptosis, fibrosis and others, vary in response of the stimuli burdened. The current review presents a handful of highlights and crosstalk involved in the communication of Nrf2 signalling network with the "up to date" reported hepatocyte cell death modes and their underling mechanisms, and addressing key cellular networks of hepatocyte fate, through a perspective of Nrf2 as a critical transcriptional factor. Collectively, labelling the cross-transduction of Nrf2-ARE axis with key cell execution pathways could provide insights to therapeutic interventions and better research outcomes.

Ethyl pyruvate, a versatile protector in inflammation and autoimmunity

Ethyl pyruvate (EP) has potent influence on redox processes, cellular metabolism, and inflammation. It has been intensively studied in numerous animal models of systemic and organ-specific disorders whose pathogenesis involves a strong immune component. Here, basic chemical and biological properties of EP are discussed, with an emphasis on its redox and metabolic activity. Further, its influence on myeloid and T cells is considered, as well as on intracellular signaling beyond its effect on immune cells. Also, the effects of EP on animal models of chronic inflammatory and autoimmune disorders are presented. Finally, a possibility to apply EP as a treatment for such diseases in humans is discussed. Scientific papers cited in this review were identified using the PubMed search engine that relies on the MEDLINE database. The reference list covers the most important findings in the field in the past twenty years.

Molecular mechanisms of ferroptosis and their role in inflammation

Ferroptosis is a type of non-apoptotic cell death, which demonstrates a definite iron-dependent expression pattern and is associated with lipid peroxidation. Glutathione peroxidase 4 (GPX4) is a key regulator of ferroptosis. Ferroptosis is involved in the development and progression of various diseases, such as cancer, tissue ischemia-reperfusion injury, neurological diseases, and respiratory diseases. It has been established previously that ferroptotic cells trigger the innate immune system by releasing inflammation-linked damage-related molecules, and immune cells stimulate the inflammatory response by recognizing the operational mechanism of ferroptosis. Some anti-inflammatory drugs have been shown to inhibit ferroptosis in certain cell models. Conversely, some ferroptosis inhibitors also exert anti-inflammatory effects in certain diseases. The present review evaluated the relationship between ferroptosis and inflammation, as well as the underlying internal mechanism, and provided valuable insights into developing novel treatment strategies for inflammatory diseases and cancer.

Pentagalloylglucose reduces AGE-induced inflammation by activating Nrf2/HO-1 and inhibiting the JAK2/STAT3 pathway in mesangial cells

Pentagalloylglucose (PGG), a gallotannin polyphenolic compound, has been found to possess a host of beneficial pharmacologic activities, such as anti-inflammatory and antioxidative activities. We previously demonstrated that PGG is capable of binding to the cell membrane of renal mesangial cells, but the pharmacological effect of PGG on diabetic renal injury and the underlying mechanisms are still not yet clear. In this study, the effects of PGG on Nrf2/HO-1 and JAK2/STAT3 signaling were explored in AGE-stimulated mesangial cells. Furthermore, the Nrf2 transcriptional inhibitor ML385 was used to verify the involvement of Nrf2 in the PGG-mediated inhibition of the JAK2/STAT3 cascade. Our results showed that PGG significantly inhibited AGE-induced ROS generation and activated AGE-inhibited Nrf2/HO-1 signaling. Moreover, AGE-induced inflammatory cytokines (IL-1β and TNF-α) and their signaling through JAK2/STAT3 were blocked by PGG. Furthermore, ML385 suppressed Nrf2/HO-1 signaling, elevated ROS and cytokine production, and activated JAK2/STAT3 cascade were reversed by PGG. These findings indicate that PGG inhibits the JAK2/STAT3 cascade by activating Nrf2/HO-1 signaling.

Mechanistic role of boswellic acids in Alzheimer's disease: Emphasis on anti-inflammatory properties

The resin/gum of Boswellia species belonging to the family of Burseraceae is a naturally occurring mixture of bioactive compounds, which was traditionally used as a folk medicine to treat conditions like chronic inflammation. Several research studies have also explored its' therapeutic potential against multiple neurodegenerative diseases such as Alzheimer's disease (AD). The main chemical constituents of this gum include boswellic acids (BAs) like 3-O-acetyl-11-keto-β boswellic acid (AKBA) that possess potent anti-inflammatory and neuroprotective properties in AD. It is also involved in inhibiting the acetylcholinesterase (AChE) activity in the cholinergic pathway and improve choline levels as well as its binding with nicotinic receptors to produce anti-inflammatory effects. Multiple shreds of evidence have demonstrated that BAs modulate key molecular targets and signalling pathways like 5-lipoxygenase/cyclooxygenase, Nrf2, NF-kB, cholinergic, amyloid-beta (Aβ), and neurofibrillary tangles formation (NFTs) that are involved in AD progression. The present review focuses on the possible mechanistic therapeutic role of BAs in modulating the 5-LOX/COX pathway in arachidonic acid metabolism, activating Nrf2 through binding of ARE, inhibiting NF-kB and AChE activity. In addition, an inhibition of amyloid plaques (Aβ) and neurofibrillary tangles (NFTs) induced neurotoxicity and neuroinflammation in AD by BAs is also discussed in this review. We have also highlighted that BAs possess beneficial effects in AD by targeting multiple molecular pathways and makes it an emerging drug candidate for treating neurodegenerative diseases.

Deregulation of signaling pathways controlling cell survival and proliferation in cancer cells alters induction of cytochrome P450 family 1 enzymes

Cytochrome P450 family 1 (CYP1) enzymes contribute both to metabolism of xenobiotics and to the control of endogenous levels of ligands of the aryl hydrocarbon receptor (AhR). Their activities, similar to other CYPs, can be altered in tumor tissues. Here, we examined a possible role of proliferative/survival pathways signaling, which is often deregulated in tumor cells, and possible links with p300 histone acetyltransferase (a transcriptional co-activator) in the control of CYP1 expression, focusing particularly on CYP1A1. Using cell models derived from human liver, we observed that the induction of CYP1A1 expression, as well as other CYP1 enzymes, was reduced in exponentially growing cells, as compared with their non-dividing counterparts. The siRNA-mediated inhibition of proliferation/pro-survival signaling pathway effectors (such as β-catenin and/or Hippo pathway effectors YAP/TAZ) increased the AhR ligand-induced CYP1A1 mRNA levels in liver HepaRG cells, and/or in colon carcinoma HCT-116 cells. The activation of proliferative Wnt/β-catenin signaling in HCT-116 cells reduced both the induction of CYP1 enzymes and the binding of p300 to the promoter of CYP1A1 or CYP1B1 genes. These results seem to indicate that aberrant proliferative signaling in tumor cells could suppress induction of CYP1A1 (or other CYP1 enzymes) via competition for p300 binding. This mechanism could be involved in modulation of the metabolism of both endogenous and exogenous substrates of CYP1A1 (and other CYP1 enzymes), with possible further consequences for alterations of the AhR signaling in tumor cells, or additional functional roles of CYP1 enzymes.

Key Signaling Pathways in Psoriasis: Recent Insights from Antipsoriatic Therapeutics

Psoriasis is a common chronic inflammatory skin disease associated with several comorbidities and reduced quality of life. In the past decades, highly effective targeted therapies have led to breakthroughs in the management of psoriasis, providing important insights into the pathogenesis. This article reviews the current concepts of the pathophysiological pathways and the recent progress in antipsoriatic therapeutics, highlighting key targets, signaling pathways and clinical effects in psoriasis.

microRNA-148a-3p-targeting p300 protects against osteoblast differentiation and osteoporotic bone reconstruction

Aim: This study sets out to investigate the possible effects of miRNA-148a-3p (miR-148a-3p) on osteoblast differentiation and bone remodeling following osteoporosis. Materials & methods: Expression of miR-148a-3p, p300, Nrf2 and differentiation-related proteins (Runx2, Osteocalcin and Col1a1) was examined in the osteoblast MC3T3-E1 cell line, followed by identification of interaction between miR-148a-3p and p300 and between p300 and Nrf2. After ectopic expression and depletion experiments in MC3T3-E1 cells, cell proliferation, osteogenic mineralization and osteogenic differentiation were measured. Ovariectomy-induced osteoporosis mouse models were established to verify function of miR-148a-3p in vivo. Results: miR-148a-3p expression was restrained and p300 and Nrf2 expression was increased during osteoblast differentiation. miR-148a-3p inhibition or p300 upregulation enhanced proliferation and osteogenic differentiation in MC3T3-E1 cells. p300 was targeted by miR-148a-3p. Additionally, miR-148a-3p reduced BMD, bone volume relative to tissue volume ratio, trabecular bone, trabecular thickness and trabecular spacing in ovariectomy mice. Conclusion: Taken together, miR-148a-3p might prevent the osteoblast differentiation and bone remodeling by disrupting p300-dependent Nrf2 pathway activation.

Emerging Therapeutic Applications for Fumarates

Fumarates are successfully used for the treatment of psoriasis and multiple sclerosis. Their antioxidative, immunomodulatory, and neuroprotective properties make fumarates attractive therapeutic candidates for other pathologies. The exact working mechanisms of fumarates are, however, not fully understood. Further elucidation of the mechanisms is required if these drugs are to be successfully repurposed for other diseases. Towards this, administration route, dosage, and treatment timing, frequency, and duration are important parameters to consider and optimize with clinical paradigms in mind. Here, we summarize the rapidly expanding literature on the pharmacokinetics and pharmacodynamics of fumarates, including a discussion on two recently FDA-approved fumarates VumerityTM and BafiertamTM. We review emerging applications of fumarates, focusing on neurological and cardiovascular diseases.

The GSK3-NRF2 Axis in Suicide

Mutations in the genes coding for tryptophan-hydrolase-2 and the scaffold protein FKBP5 are associated with an increased risk of suicide. The mutation in both cases enhances the enzymatic activity of glycogen synthase kinase-3 (GSK3). Conversely, anti-suicidal medications, such as lithium, clozapine, and ketamine, indirectly inhibit the activity of GSK3. When GSK3 is active, it promotes the metabolic removal of the transcription factor NRF2 (nuclear factor erythroid 2-related factor-2), which suppresses the transcription of multiple genes that encode anti-oxidative and anti-inflammatory proteins. Notably, several suicide-biomarkers bear witness to an ongoing inflammatory process. Moreover, alterations in serum lipid levels measured in suicidal individuals are mirrored by data obtained in mice with genetic deletion of the NRF2 gene. Inflammation is presumably causally related to both dysphoria and anger, two factors relevant for suicide ideation and attempt. Preventing the catabolism of NRF2 could be a strategy to obtain novel suicide-prophylactic medications. Possible candidates are minocycline and nicotinic-α7 agonists. The antibiotic minocycline indirectly activates NRF2-transcriptional activity, whereas the activation of nicotinic-α7 receptors indirectly inhibits GSK3.

Hemolysis transforms liver macrophages into antiinflammatory erythrophagocytes

During hemolysis, macrophages in the liver phagocytose damaged erythrocytes to prevent the toxic effects of cell-free hemoglobin and heme. It remains unclear how this homeostatic process modulates phagocyte functions in inflammatory diseases. Using a genetic mouse model of spherocytosis and single-cell RNA sequencing, we found that erythrophagocytosis skewed liver macrophages into an antiinflammatory phenotype that we defined as MarcohiHmoxhiMHC class IIlo erythrophagocytes. This phenotype transformation profoundly mitigated disease expression in a model of an anti-CD40-induced hyperinflammatory syndrome with necrotic hepatitis and in a nonalcoholic steatohepatitis model, representing 2 macrophage-driven sterile inflammatory diseases. We reproduced the antiinflammatory erythrophagocyte transformation in vitro by heme exposure of mouse and human macrophages, yielding a distinctive transcriptional signature that segregated heme-polarized from M1- and M2-polarized cells. Mapping transposase-accessible chromatin in single cells by sequencing defined the transcription factor NFE2L2/NRF2 as a critical driver of erythrophagocytes, and Nfe2l2/Nrf2 deficiency restored heme-suppressed inflammation. Our findings point to a pathway that regulates macrophage functions to link erythrocyte homeostasis with innate immunity.

Nuclear factor erythroid 2-related factor 2 as a treatment target of kidney diseases

PURPOSE OF REVIEW

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor which regulates a wider range of downstream pathways than previously thought. This review focuses on the novel findings about the internal regulatory mechanisms of Nrf2, the expanding understanding of its role in maintaining cellular homeostasis and the attempts to broaden the clinical application of its activators.

RECENT FINDINGS

Nrf2 is in charge of the maintenance of cellular homeostasis under stress and there exist the internal regulatory mechanisms for Nrf2 which have recently been elucidated. New downstream pathways of Nrf2 have been discovered, including the defense against ferroptosis, the latest concept of cell death. Several Nrf2 activators are at various stages of clinical development and are being tested in clinical trials for chronic kidney disease (CKD) including diabetic kidney disease, Alport syndrome, autosomal dominant polycystic kidney disease and focal segmental glomerulosclerosis.

SUMMARY

Nrf2 has been gathering attention as an emerging treatment target of chronic diseases which have oxidative stress and inflammation as their pathogenesis including CKD. Basic and clinical studies are under way to establish its role as a target for treatment of those diseases.

Redox Homeostasis in Poultry: Regulatory Roles of NF-κB

Redox biology is a very quickly developing area of modern biological sciences, and roles of redox homeostasis in health and disease have recently received tremendous attention. There are a range of redox pairs in the cells/tissues responsible for redox homeostasis maintenance/regulation. In general, all redox elements are interconnected and regulated by various means, including antioxidant and vitagene networks. The redox status is responsible for maintenance of cell signaling and cell stress adaptation. Physiological roles of redox homeostasis maintenance in avian species, including poultry, have received limited attention and are poorly characterized. However, for the last 5 years, this topic attracted much attention, and a range of publications covered some related aspects. In fact, transcription factor Nrf2 was shown to be a master regulator of antioxidant defenses via activation of various vitagenes and other protective molecules to maintain redox homeostasis in cells/tissues. It was shown that Nrf2 is closely related to another transcription factor, namely, NF-κB, responsible for control of inflammation; however, its roles in poultry have not yet been characterized. Therefore, the aim of this review is to describe a current view on NF-κB functioning in poultry with a specific emphasis to its nutritional modulation under various stress conditions. In particular, on the one hand, it has been shown that, in many stress conditions in poultry, NF-κB activation can lead to increased synthesis of proinflammatory cytokines leading to systemic inflammation. On the other hand, there are a range of nutrients/supplements that can downregulate NF-κB and decrease the negative consequences of stress-related disturbances in redox homeostasis. In general, vitagene-NF-κB interactions in relation to redox balance homeostasis, immunity, and gut health in poultry production await further research.

Microglial metabolic disturbances and neuroinflammation in cerebral infarction

Cerebral ischemia/reperfusion injury activates microglia, resident immune cells in the brain, and allows the infiltration of circulating immune cells into the ischemic lesions. Microglia play both exacerbating and protective roles in pathological processes and are thus often referred to as "double-edged swords." In ischemic brains, blood-borne macrophages play a role that is distinct from that of resident activated microglia. Recently, the metabolic alteration of immune cells in the pathogenesis of inflammatory disorders including cerebral infarction has become a critical target for investigation. We begin this review by describing the multifaceted functions of microglia in cerebral infarction. Next, we focus on the metabolic alterations that occur in microglia during pathological processes. We also discuss morphological changes that take place in the mitochondria, leading to functional disturbances, accompanied by alterations in microglial function. Moreover, we describe the involvement of the reactive oxygen species that are produced during aberrant metabolic activity. Finally, we discuss therapeutic strategies to ameliorate aggravative changes in metabolism.

Vernonia patula (Dryand.) Merr. and Leucas chinensis (Retz.) R. Brown exert anti-inflammatory activities and relieve oxidative stress via Nrf2 activation

ETHNOPHARMACOLOGICAL RELEVANCE

Vernonia patula (Dryand.) Merr. and Leucas chinensis (Retz.) R. Brown have anti-inflammatory properties and are popularly used as complementary and alternative medicine in Asia.

AIM OF THE STUDY

To investigate the underlying molecular mechanism and active chemicals in the ethanol extracts of V. patula (VP) and L. chinensis (LC).

MATERIALS AND METHODS

The inhibitory activities of VP and LC on lipopolysaccharide (LPS)-stimulated nitric oxide (NO) and interleukin-6 (IL-6) production were investigated in RAW264.7 macrophages and BV2 microglia. Downregulation of pro-inflammatory genes and upregulation of Nrf2 (NF-E2 p45-related factor 2)-ARE (antioxidant response element) pathway were investigated using RT-Q-PCR and Western blotting. Direct antioxidant capacities were measured using free radical scavenging and Folin-Ciocalteu assays. The flavonoids and triterpenes in VP and LC were identified by HPLC-ESI-MS.

RESULTS

VP and LC inhibited NO and IL-6 production and suppressed iNOS, IL-6, IL-1β and CCL2 gene expression. VP and LC were potent direct antioxidants and effective indirect antioxidants assayed by Nrf2 activation and induction of heme oxygenase (HO)-1, glutamate-cysteine ligase modifier subunit (GCLM) and NAD(P)H quinone oxidoreductase 1 (NQO1). Three flavonoids including apigenin (1), luteolin (2) and chryseriol (3), and one triterpene betulinic acid (4) were found in VP; while compounds 1-4 and oleanolic acid (5) were in LC.

CONCLUSION

Anti-inflammatory and antioxidant activities of VP and LC may be in great part attributed to the identified Nrf2 activating compounds, which induce expression of Phase II enzymes and attenuate the upregulation of pro-inflammatory genes.

Reductive stress in striated muscle cells

Reductive stress is defined as a condition of sustained increase in cellular glutathione/glutathione disulfide and NADH/NAD+ ratios. Reductive stress is emerging as an important pathophysiological event in several diseased states, being as detrimental as is oxidative stress. Occurrence of reductive stress has been documented in several cardiomyopathies and is an important pathophysiological factor particularly in coronary artery disease and myocardial infarction. Excess activation of the transcription factor, Nrf2-the master regulator of the antioxidant response-, consequent in most cases to defective autophagy, can lead to reductive stress. In addition, hyperglycemia-induced activation of the polyol pathway can lead to increased NADH/NAD+ ratio, which might translate into increased levels of hydrogen sulfide-via enhanced activity of cystathionine β-synthase-that would fuel reductive stress through inhibition of mitochondrial complex I. Reductive stress may be either a potential weapon against cancer priming tumor cells to apoptosis or a cancer's ally promoting tumor cell proliferation and making tumor cells resistant to reactive oxygen species-inducing drugs. In non-cancer pathological states reductive stress is definitely harmful paradoxically leading to reactive oxygen species overproduction via excess NADPH oxidase 4 activity. In face of the documented occurrence of reductive stress in several heart diseases, there is much less information about the occurrence and effects of reductive stress in skeletal muscle tissue. In the present review we describe relevant results emerged from studies of reductive stress in the heart and review skeletal muscle conditions in which reductive stress has been experimentally documented and those in which reductive stress might have an as yet unrecognized pathophysiological role. Establishing whether reductive stress has a (patho)physiological role in skeletal muscle will hopefully contribute to answer the question whether antioxidant supplementation to the general population, athletes, and a large cohort of patients (e.g. heart, sarcopenic, dystrophic, myopathic, cancer, and bronco-pulmonary patients) is harmless or detrimental.

Exploring the Use of Dimethyl Fumarate as Microglia Modulator for Neurodegenerative Diseases Treatment

The maintenance of redox homeostasis in the brain is critical for the prevention of the development of neurodegenerative diseases. Drugs acting on brain redox balance can be promising for the treatment of neurodegeneration. For more than four decades, dimethyl fumarate (DMF) and other derivatives of fumaric acid ester compounds have been shown to mitigate a number of pathological mechanisms associated with psoriasis and relapsing forms of multiple sclerosis (MS). Recently, DMF has been shown to exert a neuroprotective effect on the central nervous system (CNS), possibly through the modulation of microglia detrimental actions, observed also in multiple brain injuries. In addition to the hypothesis that DMF is linked to the activation of NRF2 and NF-kB transcription factors, the neuroprotective action of DMF may be mediated by the activation of the glutathione (GSH) antioxidant pathway and the regulation of brain iron homeostasis. This review will focus on the role of DMF as an antioxidant modulator in microglia processes and on its mechanisms of action in the modulation of different pathways to attenuate neurodegenerative disease progression.

Nuclear Factor Kappa B Signaling Complexes in Acute Inflammation

Significance: Nuclear factor kappa B (NF-κB) is a master regulator of the inflammatory response and represents a key regulatory node in the complex inflammatory signaling network. In addition, selective NF-κB transcriptional activity on specific target genes occurs through the control of redox-sensitive NF-κB interactions. Recent Advances: The selective NF-κB response is mediated by redox-modulated NF-κB complexes with ribosomal protein S3 (RPS3), Pirin (PIR). cAMP response element-binding (CREB)-binding protein (CBP)/p300, peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), activator protein-1 (AP-1), signal transducer and activator of transcription 3 (STAT3), early growth response protein 1 (EGR-1), and SP-1. NF-κB is cooperatively coactivated with AP-1, STAT3, EGR-1, and SP-1 during the inflammatory process, whereas NF-κB complexes with CBP/p300 and PGC-1α regulate the expression of antioxidant genes. PGC-1α may act as selective repressor of phospho-p65 toward interleukin-6 (IL-6) in acute inflammation. p65 and nuclear factor erythroid 2-related factor 2 (NRF2) compete for binding to coactivator CBP/p300 playing opposite roles in the regulation of inflammatory genes. S-nitrosylation or tyrosine nitration favors the recruitment of specific NF-κB subunits to κB sites. Critical Issues: NF-κB is a redox-sensitive transcription factor that forms specific signaling complexes to regulate selectively the expression of target genes in acute inflammation. Protein-protein interactions with coregulatory proteins, other transcription factors, and chromatin-remodeling proteins provide transcriptional specificity to NF-κB. Furthermore, different NF-κB subunits may form distinct redox-sensitive homo- and heterodimers with distinct affinities for κB sites. Future Directions: Further research is required to elucidate the whole NF-κB interactome to fully characterize the complex NF-κB signaling network in redox signaling, inflammation, and cancer.

A novel compound DBZ ameliorates neuroinflammation in LPS-stimulated microglia and ischemic stroke rats: Role of Akt(Ser473)/GSK3β(Ser9)-mediated Nrf2 activation

Microglia-mediated neuroinflammation plays a crucial role in the pathophysiological process of multiple neurological disorders such as ischemic stroke, yet lacks effective therapeutic agents. Previously, we discovered one novel synthetic compound, tanshinol borneol ester (DBZ), possesses anti-inflammatory and anti-atherosclerotic activities, whereas little is known about its effects in CNS. Therefore, the present study aims to explore the effects and potential mechanism of DBZ on neuroinflammation and microglial function. Our studies revealed that DBZ significantly inhibited NF-κB activity, suppressed the production of pro-inflammatory mediators meanwhile promoted M2 mediators expression in LPS-stimulated BV2 cells and mouse primary microglia cells. DBZ also exhibited antioxidant activity by enhancing Nrf2 nuclear accumulation and transcriptional activity, increasing HO-1 and NQO1 expression, and inhibiting LPS-induced ROS generation in BV2 cells. Importantly, the anti-neuroinflammatory and antioxidant effects of DBZ above were reversed by Nrf2 knockdown. Additionally, DBZ ameliorated sickness behaviors of neuroinflammatory mice induced by systemic LPS administration, and significantly reduced infract volume, improved sensorimotor and cognitive function in rats subjected to transient middle cerebral artery occlusion (tMCAO); besides, DBZ restored microglia morphological alterations and shifted the M1/M2 polarization in both murine models. Mechanistically, DBZ-induced Nrf2 nuclear accumulation and antioxidant enzymes expression were accompanied by increased level of p-Akt(Ser473) (activation) and p-GSK3β(Ser9) (inactivation), and decreased nuclear level of Fyn both in vitro and in vivo. Pharmacologically inhibiting PI3K or activating GSK3β markedly increased nuclear density of Fyn in microglia cells, which blocked the promoting effect of DBZ on Nrf2 nuclear accumulation and its antioxidant and anti-neuroinflammatory activities. Collectively, these results indicated the effects of DBZ on microglia-mediated neuroinflammation were strongly associated with the nuclear accumulation and stabilization of Nrf2 via the Akt(Ser473)/GSK3β(Ser9)/Fyn pathway. With anti-neuroinflammatory and antioxidant properties, DBZ could be a promising new drug candidate for prevention and/or treatment of cerebral ischemia and other neuroinflammatory disorders.

Protective effects of combined treatment with mild hypothermia and edaravone against cerebral ischemia/reperfusion injury via oxidative stress and Nrf2 pathway regulation

Mild hypothermia (MH) and edaravone (EDA) exert neuroprotective effects against cerebral ischemia/reperfusion (I/R) injury through activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. However, whether MH and EDA exert synergistic effects against cerebral I/R injury remains unknown. The aim of the present study was to investigate the effects and mechanism of action of MH in combination with EDA in cerebral I/R injury. A rat cerebral I/R injury model was constructed by middle cerebral artery occlusion (MCAO) followed by reperfusion, and the mice were treated by MH, EDA or the inhibitor of the Nrf2 signaling pathway brusatol (Bru). It was observed that mice treated by MCAO had higher neurological deficit scores and oxidative stress levels, and low spatial learning and memory capacity; moreover, the CA1 region of the hippocampi of the mice exhibited reduced neuronal density and viability, and reduced mitochondrial dysfunction. However, MH in combination with EDA reversed the effects of MCAO, which were blocked by Bru injection. The levels of glutathione (GSH), GSH peroxidase, catalase and superoxide dismutase in rat ischemic hemisphere tissues were reduced by Bru. Western blotting demonstrated that the combined treatment with MH and EDA promoted the nuclear localization of Nrf2, and increased the levels of NAD(P)H quinone oxidoreductase and heme oxygenase (HO)-1. In conclusion, MH combined with EDA exerted synergistic neuroprotective effects against cerebral I/R injury involving changes in the Nrf2/HO-1 pathway.

Acetyl-11-keto-β-boswellic acid ameliorates cognitive deficits and reduces amyloid-β levels in APPswe/PS1dE9 mice through antioxidant and anti-inflammatory pathways

Alzheimer's disease (AD) is a complex disease involved oxidative stress and inflammation in its pathogenesis. Acetyl-11-keto-β-boswellic acid (AKBA) is an active triterpenoid compound from extracts of Boswellia serrata, which has been widely used as an antioxidant and anti-inflammatory agent. The present study was to determine whether AKBA, a novel candidate, could protect against cognitive and neuropathological impairments in AD. We found that AKBA treatment resulted in a significant improvement of learning and memory deficits, a dramatic decrease in cerebral amyloid-β (Aβ) levels and plaque burden, a profound alleviation in oxidative stress and inflammation, and a marked reduction in activated glial cells and synaptic defects in the APPswe/PS1dE9 mice. Furthermore, amyloid precursor protein (APP) processing was remarkably suppressed with AKBA treatment by inhibiting beta-site APP cleaving enzyme 1 (BACE1) protein expression to produce Aβ in the APPswe/PS1dE9 mice brains. Mechanistically, AKBA modulated antioxidant and anti-inflammatory pathways via increasing nuclear erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) expression, and via declining phosphorylation of inhibitor of nuclear factor-kappa B alpha (IκBα) and p65. Collectively, our findings provide evidence that AKBA protects neurons against oxidative stress and inflammation in AD, and this neuroprotective effect involves the Nrf2/HO-1 and nuclear factor-kappa B (NF-κB) signaling pathways.

Akebia Saponin D suppresses inflammation in chondrocytes via the NRF2/HO-1/NF-κB axis and ameliorates osteoarthritis in mice

Akebia Saponin D promotes the translocation of NRF2 into nucleus, activates NRF2/HO-1 pathway and inhibits NF-κB pathway in chondrocytes, and ultimately alleviates osteoarthritis development.

Effects of Ethyl Pyruvate on Bile Duct Ligation-Induced Liver Fibrosis by Regulating Nrf2 Pathway and Proinflammatory Cytokines in Rats

Aim

The aim of this paper is to investigate the effects of ethyl pyruvate (EP) on experimental liver fibrosis induced by bile duct ligation (BDL) and explore the underlying molecular mechanisms.

Material and Method

Rats were randomly divided into three groups: the sham group, the BDL group, and the BDL+EP group. Liver fibrosis was induced by common bile duct ligation and was evaluated by serum biochemical parameter levels, Masson's trichrome staining, α-SMA expression, and collagen I deposition. The levels of Nrf2 signaling pathway-related antioxidant genes (Nrf2, SOD2, NQO1, and GSH-Px) in liver tissues were also measured. Meanwhile, the mRNA expression levels of HMGB1, IL-1β, TNF-α, and HSP27 were analyzed. In BDL-induced liver fibrosis rats, the successfully established model was confirmed by the significant increase of serum ALT and AST levels, the high liver fibrosis score, α-SMA expression, and collagen deposition.

Results

Compared with the BDL group, EP administration could diminish fibrosis level and substantially increase the expression of Nrf2 signaling pathway-related antioxidant genes. Furthermore, EP significantly suppressed the mRNA expression levels of HMGB1, IL-1β, TNF-α, and HSP27.

Conclusions

The results suggested that EP administration could effectively inhibit the liver fibrosis induced by BDL in rat, which may be associated with the enhanced activity of Nrf2 to mediate antioxidant enzyme system and downregulate the inflammatory genes.

Therapeutic Effects of Nrf2 Activation by Bardoxolone Methyl in Chronic Heart Failure

Oxidative stress plays an important role in the pathogenesis of chronic heart failure (CHF) in many tissues. Increasing evidence suggests that systemic activation of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) signaling can protect against postinfarct cardiac remodeling by reducing oxidative stress. However, it remains to be elucidated if Nrf2 activation exerts therapeutic effects in the CHF state. Here, we investigated the beneficial hemodynamic effects of bardoxolone methyl (2-Cyano-3,12-dioxooleana-1,9(11)-dien-28-oic acid methyl ester, CDDO-Me), a pharmacological activator of Nrf2, in a rodent model of CHF. Based on echocardiographic analysis, rats at 12 weeks post-myocardial infarction (MI) were randomly split into four groups. CDDO-Me (5 mg/kg, i.p.) was administered daily for another 2 weeks in sham and CHF rats and compared with vehicle treatment. Echocardiographic and hemodynamic analysis suggest that short-term CDDO-Me administration increased stroke volume and cardiac output in CHF rats and decreased left ventricle end-diastolic pressure. Molecular studies revealed that CDDO-Me-induced cardiac functional improvement was attributed to an increase of both Nrf2 transcription and translation, and a decrease of oxidative stress in the noninfarcted areas of the heart. Furthermore, CDDO-Me reduced NF-κB binding and increased Nrf2 binding to the CREB-binding protein, which may contribute to the selective increase of Nrf2 downstream targets, including NADPH Oxidase Quinone 1, Heme Oxygenase 1, Catalase, and Glutamate-Cysteine Ligase Catalytic Subunit, and the attenuation of myocardial inflammation in CHF rats. Our findings suggest that Nrf2 activation may provide beneficial cardiac effects in MI-mediated CHF. SIGNIFICANCE STATEMENT: Chronic heart failure (CHF) is the leading cause of death among the aged worldwide. The imbalance between pro- and antioxidant pathways is a determinant in the pathogenesis of CHF. Systemic activation of Nrf2 and antioxidant protein signaling by bardoxolone methyl may have beneficial effects on cardiac function and result in improvements by enhancing antioxidant enzyme expression and attenuating myocardial inflammation.

Ethyl pyruvate inhibits LPS induced IPEC-J2 inflammation and apoptosis through p38 and ERK1/2 pathways

The endotoxin of Gram-negative bacteria threatens the intestinal health of livestock. Ethyl pyruvate (EP) has been shown to regulate intestinal immunity and protect against cell and tissue damage. In this study, it was first verified that EP could reduce the secretion of IL-8, TNF-α, IL-6 and IL-1β in LPS-induced IPEC-J2 cells. Then, we used RNA sequencing (RNA-seq) to analyze the differentially expressed genes (DEGs) of inflammatory factors induced by LPS in IPEC-J2 cells. It was found that LPS induced the upregulation of 377 genes and the downregulation of 477 genes compared to Vehicle; LPS+EP induced the upregulation of 258 genes and the downregulation of 240 genes compared to Vehicle; and LPS+EP induced the upregulation of 373 genes and the downregulation of 188 genes compared to LPS (fold change > 1.5 and FDR < 0.01). Their enrichment pathways included the MAPK signaling pathway, PI3K-Akt signaling pathway, Toll-like receptor signaling pathway, and other pathways. Furthermore, the mRNA level of cytokines associated with inflammation and apoptosis enriched in the MAPK pathway was verified by qRT-PCR. Western blots and immunofluorescence revealed that EP significantly inhibited phosphorylated p38 and phosphorylated-ERK1/2 protein expression levels (P < 0.05). The apoptosis due to LPS reduced by EP was significantly inhibited, as shown by Annexin V-FITC/PI staining. According to the results, EP inhibited the expression of IL-8, TNF-α, IL-6 and IL-1β as well as apoptosis by inhibiting the phosphorylation of p38 and ERK1/2 in LPS-induced IPEC-J2 cells.

Clinically-approved CFTR modulators rescue Nrf2 dysfunction in cystic fibrosis airway epithelia

Cystic Fibrosis (CF) is a multi-organ progressive genetic disease caused by loss of functional cystic fibrosis transmembrane conductance regulator (CFTR) channel. Previously, we identified a significant dysfunction in CF cells and model mice of the transcription factor nuclear-factor-E2-related factor-2 (Nrf2), a major regulator of redox balance and inflammatory signaling. Here we report that approved F508del CFTR correctors VX809/VX661 recover diminished Nrf2 function and colocalization with CFTR in CF human primary bronchial epithelia by proximity ligation assay, immunoprecipitation, and immunofluorescence, concordant with CFTR correction. F508del CFTR correctors induced Nrf2 nuclear translocation, Nrf2-dependent luciferase activity, and transcriptional activation of target genes. Rescue of Nrf2 function by VX809/VX661 was dependent on significant correction of F508del and was blocked by inhibition of corrected channel function, or high-level shRNA knockdown of CFTR or F508del-CFTR. Mechanistically, F508del-CFTR modulation restored Nrf2 phosphorylation and its interaction with the coactivator CBP. Our findings demonstrate that sufficient modulation of F508del CFTR function corrects Nrf2 dysfunction in CF.

Therapeutic targeting of the NRF2 and KEAP1 partnership in chronic diseases

The transcription factor NF-E2 p45-related factor 2 (NRF2; encoded by NFE2L2) and its principal negative regulator, the E3 ligase adaptor Kelch-like ECH-associated protein 1 (KEAP1), are critical in the maintenance of redox, metabolic and protein homeostasis, as well as the regulation of inflammation. Thus, NRF2 activation provides cytoprotection against numerous pathologies including chronic diseases of the lung and liver; autoimmune, neurodegenerative and metabolic disorders; and cancer initiation. One NRF2 activator has received clinical approval and several electrophilic modifiers of the cysteine-based sensor KEAP1 and inhibitors of its interaction with NRF2 are now in clinical development. However, challenges regarding target specificity, pharmacodynamic properties, efficacy and safety remain.

Anti-Inflammatory and Neuroprotective Effects of DIPOPA (N,N-Diisopropyl-2-Oxopropanamide), an Ethyl Pyruvate Bioisoster, in the Postischemic Brain

Ethyl pyruvate (EP) is a simple aliphatic ester of pyruvic acid and has been shown to have protective properties, which have been attributed to its anti-inflammatory, anti-oxidative, and anti-apoptotic functions. In an effort to develop better derivatives of EP, we previously synthesized DEOPA (N,N-diethyl-2-oxopropanamide, a novel isoster of EP) which has greater neuroprotective effects than EP, probably due to its anti-inflammatory and anti-excitotoxic effects. In the present study, we synthesized 3 DEOPA derivatives, in which its diethylamino group was substituted with diisopropylamino, dipropylamino, or diisobutylamino groups. Among them, DIPOPA (N,N-diisopropyl-2-oxopropanamide) containing diisopropylamino group had a greater neuroprotective effect than DEOPA or EP when administered intravenously to a rat middle cerebral artery occlusion (MCAO) model at 9 h after MCAO. Furthermore, DIPOPA had a wider therapeutic window than DEOPA and a marked reduction of infarct volume was accompanied by greater neurological and behavioral improvements. In particular, DIPOPA exerted robust anti-inflammatory effects, as evidenced by marked suppressions of microglia activation and neutrophil infiltration in the MCAO model, in microglial cells, and in neutrophil-endothelial cocultures at lower concentration, and did so more effectively than DEOPA. In particular, DIPOPA remarkably suppressed neutrophil infiltration into brain parenchyma, and this effect was attributed to the expressional inhibitions of cell adhesion molecules in neutrophils of brain parenchyma and in circulating neutrophils via NF-κB inhibition. Together, these results indicate the robust neuroprotective effects of DIPOPA are attributable to its anti-inflammatory effects and suggest that DIPOPA offers a potential therapeutic means of ameliorating cerebral ischemic injury and other inflammation-related pathologies.

Cyclic Peptides in Neurological Disorders: The Case of Cyclo(His-Pro)

Communication between and within communities of cells or independent organisms is a crucial prerequisite for species survival. In response to variations in the extracellular environment, the collective behavior of cell populations can be coordinated by regulating community-level gene expression. This mechanism is strongly conserved during evolution, being shared both by bacterial communities and central nervous system cells. Notably, cyclic dipeptides (CDPs) are molecules that are implicated in these quorum sensing behaviors in both settings. Bacteria coordinate their collective behavior by producing CDPs (quorum sensing inducers) that enhance the capacity of individual members of the community to detect these signals and thus amplify the community-level response. In this review, we highlight recent data indicating that strikingly similar molecular mechanisms control communications between glial and neuronal cells to maintain homeostasis in the central nervous system, with a specific focus on the role of the thyrotropin-releasing hormone—derived CDP cyclo(His-Pro) in the protection against neurotoxic insults.

Andalucin from Artemisia lannta suppresses the neuroinflammation via the promotion of Nrf2-mediated HO-1 levels by blocking the p65-p300 interaction in LPS-activated BV2 microglia

BACKGROUND

Neuroinflammation plays an important role in many neurodegenerative conditions such as Alzheimer's disease (AD) and Parkinson disease (PD). Andalucin (ADL), a sesquiterpene lactone from Artemisia lannta, has been reported to exhibit NO inhibition in vitro. However, the effect of ADL on microglia-mediated neuroinflammation has not been investigated.

PURPOSE

This study was designed to determine the anti-neuroinflammatory effect of ADL against LPS-activated BV2 microglial cells and to explore the underlying mechanisms.

METHODS

The production of pro-inflammatory mediators and cytokines were measured by ELISA. The relevant mechanisms were analyzed by qRT-PCR, Luciferase assay, Western blot and Co-immunoprecipitation Assay.

RESULTS

ADL inhibited the LPS-induced release of NO, PGE₂, TNF-α, IL-6 and IL-1β. In addition, ADL reduced the mRNA and protein levels of iNOS and COX-2. Mechanism studies found that ADL activated Nrf2/HO-1 signaling pathway and suppressed NF-κB signaling pathway. Further investigation showed that the stimulative effect of ADL on Nrf2 transcriptional activity and the inhibitory effect of ADL on RelA transcriptional activity were due to its regulation on p300-Nrf2/p65 interaction.

CONCLUSION

ADL displayed anti-neuroinflammatory activity in LPS-activated BV2 cells. The mechanism concerns its regulatory effect on the crosstalk between Nrf2 and p65.

Gastrodin exerts robust neuroprotection in the postischemic brain via its protective effect against Zn2+-toxicity and its anti-oxidative effects in astrocytes

Gastrodin (GAS) is a predominant bioactive constituent of the Chinese herbal medicine Tianma (Gastrodia elata Blume). Many authors have reported GAS has the beneficial effect on diverse diseases of the CNS, including epilepsy, Alzheimer's disease, Parkinson's disease, and cerebral ischemia. Here, we report GAS exhibited a robust neuroprotective effect in an Sprague-Dawley rat model of stroke (transient middle cerebral artery occlusion, tMCAO), and show that the underlying molecular mechanism involves its protective effect against Zn²⁺-toxicity and its anti-oxidative effects in astrocytes. Intraperitoneal administration of GAS (40 mg/kg) after MCAO reduced mean infarct volume to 30.1 ± 5.9% of that of MCAO controls and this neuroprotective effect was accompanied by neurological function recoveries which was measured using modified neurological severity score (mNSS). Interestingly, GAS induced up-regulation and nuclear translocation of Nrf2, and subsequently increased the expressions of anti-oxidative genes, such as, HO-1 and GCLM, in astrocytes. Furthermore, GAS co- or pre-treatment markedly suppressed Zn²⁺-induced cell death caused by excessive ROS production and PARP-1 induction. We found that GAS suppressed p67 expression and PAR formation in astrocytes, which might underlie the anti- Zn²⁺-toxicity and anti-oxidative effects of GAS in astrocytes. These findings indicate GAS protects astrocytes from Zn²⁺-induced toxicity and oxidative stress and these effects contribute to its neuroprotective effects in the postischemic brain.