Nrf-2-HO-1-HMGB1 axis: an important therapeutic approach for protection against myocardial ischemia and reperfusion injury

Eicosapentaenoic Acid Improves Endothelial Nitric Oxide Bioavailability Via Changes in Protein Expression During Inflammation

BACKGROUND

Endothelial cell (EC) dysfunction involves reduced nitric oxide (NO) bioavailability due to NO synthase uncoupling linked to increased oxidation and reduced cofactor availability. Loss of endothelial function and NO bioavailability are associated with inflammation, including leukocyte activation. Eicosapentaenoic acid (EPA) administered as icosapent ethyl reduced cardiovascular events in REDUCE-IT (Reduction of Cardiovascular Events With Icosapent Ethyl-Intervention Trial) in relation to on-treatment EPA blood levels. The mechanisms of cardiovascular protection for EPA remain incompletely elucidated but likely involve direct effects on the endothelium.

METHODS AND RESULTS

In this study, human ECs were treated with EPA and challenged with the cytokine IL-6 (interleukin-6). Proinflammatory responses in the ECs were confirmed by ELISA capture of sICAM-1 (soluble intercellular adhesion molecule-1) and TNF-α (tumor necrosis factor-α). Global protein expression was determined using liquid chromatography-mass spectrometry tandem mass tag. Release kinetics of NO and peroxynitrite were monitored using porphyrinic nanosensors. IL-6 challenge induced proinflammatory responses from the ECs as evidenced by increased release of sICAM-1 and TNF-α, which correlated with a loss of NO bioavailability. ECs pretreated with EPA modulated expression of 327 proteins by >1-fold (P<0.05), compared with IL-6 alone. EPA augmented expression of proteins involved in NO production, including heme oxygenase-1 and dimethylarginine dimethylaminohydrolase-1, and 34 proteins annotated as associated with neutrophil degranulation. EPA reversed the endothelial NO synthase uncoupling induced by IL-6 as evidenced by an increased [NO]/[peroxynitrite] release ratio (P<0.05).

CONCLUSIONS

These direct actions of EPA on EC functions during inflammation may contribute to its distinct cardiovascular benefits.

Nrf-2 modulates excitability of hippocampal neurons by regulating ferroptosis and neuroinflammation after subarachnoid hemorrhage in rats

Excitability of hippocampal neurons in subarachnoid hemorrhage (SAH) rats has not been well studied. The rat SAH model was applied in this study to explore the role of nuclear factor E2-related factor (Nrf-2) in the early brain injury of SAH. The neural excitability of CA1 pyramidal cells (PCs) in SAH rats was evaluated by using electrophysiology experiments. Ferroptosis and neuroinflammation were measured by ELISA, transmission electron microscopy and western blotting. Our results indicated that SAH induced neurological deficits, brain edema, ferroptosis, neuroinflammation and neural excitability in rats. Ferrostatin-1 treatment significantly decreased the expression and distribution of IL-1β, IL-6, IL-10, TGF-β and TNF-α. Inhibiting ferroptosis by ferrostatin-1 can attenuate neural excitability, neurological deficits, brain edema and neuroinflammation in SAH rats. Inhibiting the expression of Nrf-2 significantly increased the neural excitability and the levels of IL-1β, IL-6, IL-10, TGF-β and TNF-α in Fer-1-treated SAH rats. Taken together, inhibiting the Nrf-2 induces early brain injury, brain edema and the inflammatory response with increasing of neural excitability in Fer-1-treated SAH rats. These results have indicated that inhibiting ferroptosis, neuroinflammation and neural excitability attenuates early brain injury after SAH by regulating the Nrf-2.

Potential regulatory role of the Nrf2/HMGB1/TLR4/NF-κB signaling pathway in lupus nephritis

OBJECTIVES

Systemic lupus erythematosus is an autoimmune disease that involves multiple organ systems. One of its major complications, lupus nephritis (LN), is associated with a high mortality rate, and children-onset LN have a more severe course and worse prognosis than adults. Oxidative stress and inflammatory responses are involved in LN development and pathogenesis. Thus, this study aimed to explore the role of signaling regulation of the Nrf2/HMGB1/TLR/NF-κB pathway in LN pathogenesis and unravel the expression of TLR4+CXCR4+ plasma cells subset (PCs) in LN.

METHODS

C57BL/6 and MRL/lpr mice were divided into four groups: control, model, vector control, and Nrf2 overexpression groups. The vector control and Nrf2 overexpression groups were injected with adenoviral vectors into the kidney in situ. Pathological changes in kidney tissues were observed by hematoxylin-eosin staining. The expression of Nrf2, HMGB1, TLR4, NF-κB, and downstream inflammatory factors in kidney samples was analyzed by quantitative polymerase chain reaction, western blotting, and enzyme-linked immunosorbent assay. The ratios of TLR4+CXCR4+ PC subsets in the blood and kidneys of mice were determined by flow cytometry.

RESULTS

In MRL/lpr mice, Nrf2 was downregulated while HMGB1/TLR4/NF-κB pathway proteins were upregulated. Nrf2 overexpression decreased the expression of HMGB1, TLR4, NF-κB, and its downstream inflammatory cytokines (IL-1β and TNFα). These cytokines were negatively correlated with an increase in Nrf2 content. PC and TLR4 + CXCR4 + PCs in the blood and kidney samples were significantly increased in MRL/lpr mice; however, they were decreased upon Nrf2 overexpression.

CONCLUSION

This study showed severe kidney injury in an LN mouse model and an increased ratio of TLR4 + CXCR4 + PCs. Furthermore, we observed that Nrf2 regulates LN immune response through the Nrf2/HMGB1/TLR4/NF-κB pathway, which can be considered an important target for LN treatment. The clinical value of the findings of our study requires further investigation.

Release of High-Mobility Group Box-1 after a Raynaud's Attack Leads to Fibroblast Activation and Interferon-γ Induced Protein-10 Production: Role in Systemic Sclerosis Pathogenesis

Raynaud's Phenomenon (RP) leading to repetitive ischemia and reperfusion (IR) stress, is the first recognizable sign of systemic sclerosis (SSc) leading to increased oxidative stress. High-mobility group box-1 (HMGB1) is a nuclear factor released by apoptotic and necrotic cells after oxidative stress. Since HMGB1 can signal through the receptor for advanced glycation end products (RAGE), we investigated whether an RP attack promotes the release of HMGB1, leading to fibroblast activation and the upregulation of interferon (IFN)-inducible genes. A cold challenge was performed to simulate an RP attack in patients with SSc, primary RP (PRP), and healthy controls. We measured levels of HMGB1 and IFN gamma-induced Protein 10 (IP-10) at different time points in the serum. Digital perfusion was assessed by photoplethysmography. In vitro, HMGB1 or transforming growth factor (TGF-β1) (as control) was used to stimulate healthy human dermal fibroblasts. Inflammatory, profibrotic, and IFN-inducible genes, were measured by RT-qPCR. In an independent cohort, sera were obtained from 20 patients with SSc and 20 age- and sex-matched healthy controls to determine HMGB1 and IP-10 levels. We found that HMGB1 levels increased significantly 30 min after the cold challenge in SSc compared to healthy controls. In vitro stimulation with HMGB1 resulted in increased mRNA expression of IP-10, and interleukin-6 (IL-6) while TGF-β1 stimulation promoted IL-6 and Connective Tissue Growth Factor (CTGF). In serum, both HMGB1 and IP-10 levels were significantly higher in patients with SSc compared to healthy controls. We show that cold challenge leads to the release of HMGB1 in SSc patients. HMGB1 induces IP-10 expression in dermal fibroblasts partly through the soluble RAGE (sRAGE) axis suggesting a link between RP attacks, the release of HMGB1 and IFN-induced proteins as a putative early pathogenetic mechanism in SSc.

Dao-Chi Powder Ameliorates Pancreatitis-Induced Intestinal and Cardiac Injuries via Regulating the Nrf2-HO-1-HMGB1 Signaling Pathway in Rats

Dao-Chi powder (DCP) has been widely used in the treatment of inflammatory diseases in the clinical practice of traditional Chinese medicine, but has not been used in acute pancreatitis (AP). This study aimed to evaluate the effect of DCP on severe AP (SAP) and SAP-associated intestinal and cardiac injuries. To this end, an SAP animal model was established by retrograde injection of 3.5% taurocholic acid sodium salt into the biliopancreatic ducts of rats. Intragastric DCP (9.6 g/kg.BW) was administered 12 h after modeling. The pancreas, duodenum, colon, heart and blood samples were collected 36 h after the operation for histological and biochemical detection. The tissue distributions of the DCP components were determined and compared between the sham and the SAP groups. Moreover, molecular docking analysis was employed to investigate the interactions between the potential active components of DCP and its targets (Nrf2, HO-1, and HMGB1). Consequently, DCP treatment decreased the serum levels of amylase and the markers of gastrointestinal and cardiac injury, further alleviating the pathological damage in the pancreas, duodenum, colon, and heart of rats with SAP. Mechanistically, DCP rebalanced the pro-/anti-inflammatory cytokines and inhibited MPO activity and MDA levels in these tissues. Furthermore, Western blot and RT-PCR results showed that DCP intervention enhanced the expression of Nrf2 and HO-1 in the duodenum and colon of rats with SAP, while inhibiting the expression of HMGB1 in the duodenum and heart. HPLC-MS/MS analysis revealed that SAP promoted the distribution of ajugol and oleanolic acid to the duodenum, whereas it inhibited the distribution of liquiritigenin to the heart and ajugol to the colon. Molecular docking analysis confirmed that the six screened components of DCP had relatively good binding affinity with Nrf2, HO-1, and HMGB1. Among these, oleanolic acid had the highest affinity for HO-1. Altogether, DCP could alleviated SAP-induced intestinal and cardiac injuries via inhibiting the inflammatory responses and oxidative stress partially through regulating the Nrf2/HO-1/HMGB1 signaling pathway, thereby providing additional supportive evidence for the clinical treatment of SAP.

Glycyrrhiza uralensis Fisch. and its active components mitigate Semen Strychni-induced neurotoxicity through regulating high mobility group box 1 (HMGB1) translocation

Semen Strychni has long been used for the treatment of rheumatoid arthritis, facioplegia and myasthenia gravis due to its anti-inflammation and anti-nociceptive properties in China. However, the fatal neurotoxicity of Semen Strychni has limited its wider clinical application. To investigate the acute toxicity induced by Semen Strychni and the detoxification of liquorice, we evaluated inflammation, oxidative stress and the translocation of high mobility group box 1 (HMGB1) in rats. As a result, there were obvious oxidative stress and inflammation in hippocampus after the Semen Strychni extracts (STR) treatment in rats. Liquorice extracts (LE) and its three active monomers - glycyrrhizic acid (GA), liquiritigenin (LIQ), isoliquiritigenin (ISL) showed the potential for mitigating STR-induced neurotoxicity. HMGB1 levels in cytoplasm and serum and the levels of two downstream receptors RAGE and TLR4 were significantly increased after STR treatment. Through using LE and the monomers, the nucleocytoplasmic transport and release of HMGB1 were inhibited. In addition, the binding between HMGB1 and TLR4 was weakened in detoxification groups comparing with the STR group. Taken together, these findings indicated that liquorice and its active components alleviated acute neurotoxicity induced by Semen Strychni partly via HMGB1-related pathway.

The mechanism of HMGB1 secretion and release

High mobility group box 1 (HMGB1) is a nonhistone nuclear protein that has multiple functions according to its subcellular location. In the nucleus, HMGB1 is a DNA chaperone that maintains the structure and function of chromosomes. In the cytoplasm, HMGB1 can promote autophagy by binding to BECN1 protein. After its active secretion or passive release, extracellular HMGB1 usually acts as a damage-associated molecular pattern (DAMP) molecule, regulating inflammation and immune responses through different receptors or direct uptake. The secretion and release of HMGB1 is fine-tuned by a variety of factors, including its posttranslational modification (e.g., acetylation, ADP-ribosylation, phosphorylation, and methylation) and the molecular machinery of cell death (e.g., apoptosis, pyroptosis, necroptosis, alkaliptosis, and ferroptosis). In this minireview, we introduce the basic structure and function of HMGB1 and focus on the regulatory mechanism of HMGB1 secretion and release. Understanding these topics may help us develop new HMGB1-targeted drugs for various conditions, especially inflammatory diseases and tissue damage.

A nuclear protein that gets released after cell death or is actively secreted by immune cells offers a promising therapeutic target for treating diseases linked to excessive inflammation. Daolin Tang from the University of Texas Southwestern Medical Center in Dallas, USA, and colleagues review how cellular stresses can trigger the accumulation of HMGB1, a type of alarm signal protein that promotes the recruitment and activation of inflammation-promoting immune cells. The researchers discuss various mechanisms that drive both passive and active release of HMGB1 into the space around cells. These processes, which include enzymatic modifications of the HMGB1 protein, cell–cell interactions and molecular pathways of cell death, could be targeted by drugs to lessen tissue damage and inflammatory disease caused by HMGB1-induced immune responses

Liraglutide protects against lethal renal ischemia-reperfusion injury by inhibiting high-mobility group box 1 nuclear-cytoplasmic translocation and release

Liraglutide, a glucagon-like peptide-1 receptor (GLP-1R) agonist, has been reported to exert protective effects against myocardial, hepatic, and gastric ischemia-reperfusion injury (IRI), but whether it can protect against renal IRI remains unknown. Here, a lethal renal IRI model was established with a 100% mortality rate in untreated mice. Treatment with liraglutide involving a regimen of multiple doses resulted in 100% survival, remarkable preservation of renal function, a significant reduction in pathological damage, and blunted upregulation of TNF-α, IL-1β, IL-6, MCP-1, TLR-2, TLR-4, and RAGE mRNA. We found that liraglutide treatment dramatically inhibited ischemia-induced nucleocytoplasmic translocation and release of HMGB1. This inhibition was associated with a marked decrease (~ 60%) in nuclear histone acetyltransferase activity. In addition, the protective effects of liraglutide on renal IRI were largely abolished by the administration of exogenous HMGB1. When the GLP-1R antagonist exendin (9-39) was given to mice before each liraglutide administration, or GLP-1R-/- mice were used for the renal IRI experiments, the protective effect of liraglutide on renal IRI was partially reversed. Moreover, liraglutide pretreatment significantly inhibited HMGB1 nucleocytoplasmic translocation during hypoxic culture of HK-2 cells in vitro, but the addition of exendin (9-39) significantly eliminated this inhibition. We demonstrate here that liraglutide can exert a strong protective effect on lethal renal IRI in mice. This protection appears to be related to the inhibition of HMGB1 nuclear-cytoplasmic translocation and release and partially depends on GLP-1R. Thus, liraglutide may be therapeutically useful for the clinical prevention and treatment of organ IRI.

The Immune Tolerance Role of the HMGB1-RAGE Axis

The disruption of the immune tolerance induces autoimmunity such as systemic lupus erythematosus and vasculitis. A chromatin-binding non-histone protein, high mobility group box 1 (HMGB1), is released from the nucleus to the extracellular milieu in particular environments such as autoimmunity, sepsis and hypoxia. Extracellular HMGB1 engages pattern recognition receptors, including Toll-like receptors (TLRs) and the receptor for advanced glycation endproducts (RAGE). While the HMGB1-RAGE axis drives inflammation in various diseases, recent studies also focus on the anti-inflammatory effects of HMGB1 and RAGE. This review discusses current perspectives on HMGB1 and RAGE’s roles in controlling inflammation and immune tolerance. We also suggest how RAGE heterodimers responding microenvironments functions in immune responses.

The Time-Course of Antioxidant Irisin Activity: Role of the Nrf2/HO-1/HMGB1 Axis

The production of free radicals is one of the basic mechanisms giving rise to the antimicrobial activity of macrophages; however, excessive accumulation of reactive oxygen species (ROS) can lead to cell damage, cell death, and release of the highly proinflammatory alarmin high-mobility group box 1 (HMGB1). This study aimed to evaluate the kinetics of antioxidant properties of the adipomyokine irisin administered shortly before or after macrophage activation to assess its effect on the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1)/HMGB1 pathway. The studies were performed on RAW 264.7 mouse macrophages treated with irisin (0, 25, and 50 nM) 2 h before or after lipopolysaccharide (LPS) stimulation. The effectiveness of respiratory burst and the expression of key factors of the antioxidant pathway, such as HO-1, Nrf2, superoxide dismutase 1 (SOD-1), SOD-2, glutathione peroxidase (GPx), catalase-9 (Cat-9), and HMGB1, were assessed. Irisin (50 nM) effectively reduced the free-radical production by macrophages. Furthermore, in both models, irisin altered the kinetics of expression of key factors of the downstream Nrf2/HO-1/HMGB1 pathway, leading to the increased production of Nrf2 and HO-1 and significantly reduced expression and release of HMGB1. In conclusion, irisin is a modulator of the Nrf2/HO-1/HMGB1 pathway and shows antioxidative and anti-inflammatory effects when administered both before and shortly after the activation of inflammatory mechanisms in mouse macrophages.

New insights into the protection of growth hormone in cisplatin-induced nephrotoxicity: The impact of IGF-1 on the Keap1-Nrf2/HO-1 signaling

AIMS

Cisplatin (CDDP) is an effective antineoplastic agent, however, its serious nephrotoxicity limits therapeutic use. Human growth hormone (hGH) has proved antioxidant and anti-inflammatory activities. The present study aimed to investigate the nephroprotective effects of hGH against CDDP-induced nephrotoxicity and the mechanisms underlying this nephroprotection.

MAIN METHODS

Male albino rats injected with CDDP (7 mg/kg) and nephrotoxicity indices, oxidative stress and inflammatory biomarkers (high mobility group box protein-1 (HMGB-1), soluble epoxide hydrolase (sEH), and nuclear factor-kappa B (NF-κB)) were assessed. Also, insulin-like growth factor-1 (IGF-1) and Nuclear factor-erythroid-2 (Nrf2)/heme oxygenase-1 (HO-1) pathway were assessed.

KEY FINDINGS

hGH (1 mg/kg) improved kidney function and antioxidant systems and showed intact renal tubular epithelium. Cisplatin upregulated the HMGB-1/NF-κB and downregulated Nrf2/HO-1 pathways which were reversed by hGH and aligned with increased renal IGF-1 expression. Also, IGF-1/sEH crosstalk might be involved in hGH nephroprotection. Moreover, hGH downregulated HSP70 and caspase-3 expressions.

SIGNIFICANCE

these results concluded that hGH can attenuate the inflammation and oxidative stress attained by CDDP probably through inhibition of Nrf2/HO-1 pathway. We also suggested that Keap1/Nrf2-mediated upregulation of the antioxidant HO-1 might inhibit HMGB-1/NF-κB signaling and thus provide the principal protection mechanism offered by hGH against CDDP-induced kidney injury.

Cardioprotective role of azafrin in against myocardial injury in rats via activation of the Nrf2-ARE pathway

BACKGROUND

The root of Centranthera grandiflora Benth. is a Chinese ethnodrug known as Ye-Can-Dou-Gen (YCDG) and has been widely used to treat cardiovascular diseases in Hmong, Yunnan Province, China; however, its mechanisms of action were largely unknown. Azafrin, a natural carotenoid, is one of the most abundant active ingredients in YCDG.

PURPOSE

We aimed to explore the cardioprotective effects of azafrin on myocardial infarction (MI) and myocardial ischaemia-reperfusion (MIR) injury and to clarify its underlying myocardial protective mechanisms.

METHODS

The in vitro cardioprotective effects of azafrin against oxidative stress injury in H9c2 cells were assessed by the ferric reducing antioxidant power (FRAP) assay and a viability assay in the presence of H₂O₂-induced oxidative insults, whereas the in vivo effects were assessed with the echocardiographic and histopathological evaluation together with 2,3,5-triphenyltetrazolium chloride (TTC) and serum biochemical analyses in vivo. Then, we used the luciferase reporter gene assay to measure Nrf2 transcriptional activity in HEK 293 cells and analysed the expression levels of enzymes downstream of Nrf2-ARE signalling by q-PCR and western blotting.

RESULTS

Azafrin showed higher FRAP values than FeSO₄ and exhibited prophylactic and therapeutic potency against H₂O₂-induced cell injury. Additionally, azafrin treatment dramatically improved cardiac function; ameliorated the infarct size and pathological changes in rats; decreased the levels of MDA, cTnI, and myocardial enzymes and elevated SOD activity in vivo. In addition, azafrin significantly elevated the transcriptional activity of Nrf2 in HEK 293 cells and up-regulated the mRNA expression levels of genes downstream of Nrf2-ARE pathway activation in H9c2 cells. Furthermore, the protein expression levels of HO-1 and NQO1 in the cytoplasm and Nrf2 in the nucleus were also up-regulated in both the in vivo and in vitro experiments.

CONCLUSION

Azafrin exhibited cardioprotective effects against myocardial injury via activation of the Nrf2-ARE pathway. As a natural carotenoid antioxidant, this molecule represents a promising cardioprotective adjuvant for the prophylaxis and treatment of ischaemic heart diseases.

Tussilagone Inhibits the Inflammatory Response and Improves Survival in CLP-Induced Septic Mice

Tussilagone, extracted from Tussilago farfara is an oriental medicine used for asthma and bronchitis. We investigated its mechanism of action, its inhibitory effects on lipopolysaccharide-induced inflammation in macrophages, and its impact on viability in a cecal ligation and puncture (CLP)-induced mouse model of sepsis. Tussilagone suppressed the expression of the inflammatory mediators, nitric oxide and prostaglandin E2, and the inflammatory cytokines, tumor necrosis factor-alpha (TNF-α) and high-mobility group box 1 (HMGB1), in lipopolysaccharide-stimulated RAW 264.7 cells and peritoneal macrophages. Tussilagone also reduced the activation of the mitogen-activated protein kinases and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) involved in the activation of various inflammatory mediators in activated macrophages. Moreover, tussilagone administration (1 mg/kg and 10 mg/kg) produced decreased mortality and lung injury in CLP-activated septic mice. Augmented expression of cyclooxygenase (COX)-2 and TNF-α in pulmonary alveolar macrophages of septic mice were attenuated by tussilagone administration. Tussilagone also suppressed the induction of nitric oxide, prostaglandin E2, TNF-α and HMGB1 in the serum of the septic mice. Overall, tussilagone exhibited protective effects against inflammation and polymicrobial sepsis by suppressing inflammatory mediators possibly via the inhibition of NF-κB activation and the MAP kinase pathway. These results suggest the possible use of tussilagone for developing novel therapeutic modalities for sepsis and other inflammatory diseases.

1,25-Dihydroxyvitamin D Inhibits LPS-Induced High-Mobility Group Box 1 (HMGB1) Secretion via Targeting the NF-E2-Related Factor 2-Hemeoxygenase-1-HMGB1 Pathway in Macrophages

1,25-Dihydroxyvitamin D [1,25(OH)₂D₃] is recognized as a key mediator of inflammatory diseases, including sepsis. Clinical studies demonstrate that 1,25 (OH)₂D₃ protects patients from sepsis, but clinical treatment with 1,25(OH)₂D₃ is rare. In this study, we report that 1,25(OH)₂D₃ treatment has beneficial effects and improves the survival rate in LPS-induced mouse sepsis model by blocking the secretion of high-mobility group box 1 (HMGB1), a key late regulator of sepsis. LPS-induced HMGB1 secretion is attenuated by 1,25(OH)₂D₃via blocking HMGB1 translocation from the nucleus to the cytoplasm in macrophages. 1,25(OH)₂D₃ can induce the expression of hemeoxygenase-1 (HO-1), which is essential for blocking HMBG1 nuclear translocation and its secretion. When siHO-1 or an HO-1 inhibitor are used, the effect of 1,25(OH)₂D₃ on inhibition of HMGB1 secretion is suppressed. Considering that HO-1 is a downstream gene of NF-E2-related factor 2 (Nrf2), we further confirm that Nrf2 activation can be activated by 1,25(OH)₂D₃ upon LPS exposure. Together, we provide evidence that 1,25(OH)₂D₃ attenuates LPS-induced HMGB1 secretion via the Nrf2/HO-1 pathway in macrophages.

Hormetic modulation of hepatic insulin sensitivity by advanced glycation end products

Because of the paucity of information regarding metabolic effects of advanced glycation end products (AGEs) on liver, we evaluated effects of AGEs chronic administration in (1) insulin sensitivity; (2) hepatic expression of genes involved in AGEs, glucose and fat metabolism, oxidative stress and inflammation and; (3) hepatic morphology and glycogen content. Rats received intraperitoneally albumin modified (AlbAGE) or not by advanced glycation for 12 weeks. AlbAGE induced whole-body insulin resistance concomitantly with increased hepatic insulin sensitivity, evidenced by activation of AKT, inactivation of GSK3, increased hepatic glycogen content, and decreased expression of gluconeogenesis genes. Additionally there was reduction in hepatic fat content, in expression of lipogenic, pro-inflamatory and pro-oxidative genes and increase in reactive oxygen species and in nuclear expression of NRF2, a transcription factor essential to cytoprotective response. Although considered toxic, AGEs become protective when administered chronically, stimulating AKT signaling, which is involved in cellular defense and insulin sensitivity.

Effect of Heme Oxygenase-1 on Mitofusin-1 protein in LPS-induced ALI/ARDS in rats

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is a common and important oxidative stress in the lung. Mitochondrial fusion responds to the normal morphology and function of cells and is finely regulated by mitochondrial fusion proteins, such as mitofusin-1 protein (Mfn1), mitofusin-2 protein (Mfn2) and optical atrophy 1 (OPA1). Additionally, Mfn1 has been identified as the most important protein in mitochondrial fusion. Heme oxygenase-1 (HO-1) is a stress-inducible protein that plays a critical role in protecting against oxidative stress. However, whether the protection of HO-1 is related to mitochondrial fusion is still a question. Thus, our in vitro and in vivo experiments aimed to identify the relationship between HO-1 and Mfn1. Here, we used Hemin and ZnPP-IX as treatments in an in vivo experiment. Then, HO-1 and Mfn1 were measured using RT-PCR and Western blotting. Supernatants were analyzed for MDA, SOD, and ROS. Our results implied that HO-1 upregulation suppressed oxidative stress induced by LPS, and the possible mechanism could be associated with Mfn1 and the PI3K/Akt pathway.

Anti-Inflammatory and Organ-Protective Effects of Resveratrol in Trauma-Hemorrhagic Injury

Resveratrol, a natural polyphenolic compound of grape and red wine, owns potential anti-inflammatory effects, which results in the reduction of cytokines overproduction, the inhibition of neutrophil activity, and the alteration of adhesion molecules expression. Resveratrol also possesses antioxidant, anti-coagulation and anti-aging properties, and it may control of cell cycle and apoptosis. Resveratrol has been shown to reduce organ damage following traumatic and shock-like states. Such protective phenomenon is reported to be implicated in a variety of intracellular signaling pathways including the activation of estrogen receptor, the regulation of the sirtuin 1/nuclear factor-kappa B and mitogen-activated protein kinases/hemeoxygenase-1 pathway, and the mediation of proinflammatory cytokines and reactive oxygen species formation and reaction. In the recent studies, resveratrol attenuates hepatocyte injury and improves cardiac contractility due to reduction of proinflammatory mediator expression and ameliorates hypoxia-induced liver and kidney mitochondrial dysfunction following trauma and hemorrhagic injuries. Moreover, through anti-inflammatory effects and antioxidant properties, the resveratrol is believed to protect organ function in trauma-hemorrhagic injury. In this review, the organ-protective and anti-inflammatory effects of resveratrol in trauma-hemorrhagic injury will be discussed.

Higenamine regulates Nrf2-HO-1-Hmgb1 axis and attenuates intestinal ischemia-reperfusion injury in mice

INTRODUCTION

Intestinal ischemia and reperfusion (IR) syndrome is a life-threatening dilemma caused by diverse events. Higenamine (HG), an active ingredient of Aconiti Lateralis Radix Praeparata, has been traditionally used as a heart stimulant and anti-inflammatory agent in oriental countries. But the function of HG on intestine IR injury has never been investigated.

MATERIALS AND METHODS

Mice underwent a 2 cm midline laparotomy, and the superior mesenteric artery (SMA) was obstructed by micro-vascular clamp to induce intestinal ischemia.

RESULTS

In our current study, HG increases mouse intestinal epithelial (IEC-6) cell viability through induced heme oxygenase-1 (HO-1) production in vitro. In our in vivo murine intestinal IR injury model, the increased HO-1 protein level and activity, decreased intestinal injury score, Myeloperoxidase (MPO) activity, and inflammatory cytokine expression induced by HG were all abolished with additional treatment of HO-1 inhibitor zinc protoporphyrin IX (ZnPPIX). Furthermore, HG reduced high mobility group box-1 (Hmgb1) expression in IR injury-performed intestine which was inhibited by additional administration of ZnPPIX. And HG treatment significantly decreased HO-1 expression in nuclear factor erythroid 2-related factor (Nrf-2) SiRNA-transfected cells but not in control SiRNA-transfected cells.

CONCLUSION

Our study provides evidence HG regulates Nrf2-HO-1-Hmgb1 axis and attenuates intestinal IR injury in mice.

HMGB1 in health and disease

Complex genetic and physiological variations as well as environmental factors that drive emergence of chromosomal instability, development of unscheduled cell death, skewed differentiation, and altered metabolism are central to the pathogenesis of human diseases and disorders. Understanding the molecular bases for these processes is important for the development of new diagnostic biomarkers, and for identifying new therapeutic targets. In 1973, a group of non-histone nuclear proteins with high electrophoretic mobility was discovered and termed high-mobility group (HMG) proteins. The HMG proteins include three superfamilies termed HMGB, HMGN, and HMGA. High-mobility group box 1 (HMGB1), the most abundant and well-studied HMG protein, senses and coordinates the cellular stress response and plays a critical role not only inside of the cell as a DNA chaperone, chromosome guardian, autophagy sustainer, and protector from apoptotic cell death, but also outside the cell as the prototypic damage associated molecular pattern molecule (DAMP). This DAMP, in conjunction with other factors, thus has cytokine, chemokine, and growth factor activity, orchestrating the inflammatory and immune response. All of these characteristics make HMGB1 a critical molecular target in multiple human diseases including infectious diseases, ischemia, immune disorders, neurodegenerative diseases, metabolic disorders, and cancer. Indeed, a number of emergent strategies have been used to inhibit HMGB1 expression, release, and activity in vitro and in vivo. These include antibodies, peptide inhibitors, RNAi, anti-coagulants, endogenous hormones, various chemical compounds, HMGB1-receptor and signaling pathway inhibition, artificial DNAs, physical strategies including vagus nerve stimulation and other surgical approaches. Future work further investigating the details of HMGB1 localization, structure, post-translational modification, and identification of additional partners will undoubtedly uncover additional secrets regarding HMGB1's multiple functions.