Free radical scavenger (edaravone) prevents endotoxin-induced liver injury after partial hepatectomy in rats

Edaravone in Digestive Diseases - A Narrative Review

Digestive diseases represent a diverse and complex group of systemic disorders, often marked by intricate pathogenic mechanisms and substantial rates of morbidity, disability, and mortality. While effective therapies exist for certain conditions, such as peptic ulcers, gastrointestinal hemorrhage, and viral hepatitis, many others remain difficult to manage due to their limited treatment options, poor response to current therapies, and multifactorial etiologies. As a result, there is a pressing need to develop novel therapeutic agents that offer greater specificity and improved clinical outcomes. Edaravone, a free radical scavenger widely used in the management of neurological disorders, has demonstrated a favorable safety profile and minimal adverse effects. Recent research has expanded our understanding of Edaravone's pharmacological actions, revealing its broad therapeutic potential beyond the nervous system. Its capacity to neutralize reactive oxygen species, reduce oxidative stress, suppress inflammation, inhibit apoptosis, modulate immune function, and enhance tissue repair positions it as a promising candidate for treating digestive disorders. This review highlights current advances in the application of Edaravone in digestive disease models and clinical settings, to offer new perspectives for future prevention, therapeutic strategies, and scientific investigation in this field.

1-phenyl-3-methyl-5-pyrazolone activates the AMPK pathway to alleviate western-diet induced metabolic dysfunction-associated steatohepatitis in mice

BACKGROUND & AIMS

Approved drugs for the treatment of metabolic dysfunction-associated steatohepatitis (MASH) are limited, although it has become the most common chronic liver disease worldwide. 1-phenyl-3-methyl-5-pyrazolone (PMP) possesses various biological effects such as anti-inflammatory and antioxidant. However, the effects and underlying mechanism of PMP in MASH remain unclear.

METHODS

Steatosis cells were induced by palmitate/oleic acid (PO). Then, the contents of lipids and reactive oxygen species were measured. To further investigate the effects of PMP on MASH models, C57BL/6J mice were fed a western diet (WD) for 24 weeks and PMP was administered daily by intragastric gavage. Serum enzymes and lipids were assayed by a biochemistry analyzer. RNA sequencing, real-time qPCR, and western blotting were used to measure the expression of different genes. Histological analysis of the liver included HE, Oil red O, and Sirius red staining.

RESULTS

PMP alleviated lipid accumulation and oxidative stress induced by PO (P < 0.001). In vivo, WD-induced significant elevation of blood glucose and serum lipids were reduced by PMP (P < 0.05). Furthermore, PMP effectively prevented hepatic steatosis, inflammation, and fibrosis in MASH mice. Western blot results suggested PMP promoted the phosphorylation of LKB1 and AMPKα at T172, which is a marker of activation of the AMPK pathway. RNA sequencing also demonstrated that PMP facilitated the activation of the AMPK pathway. Furthermore, the protective effects of PMP on steatosis cells and MASH mice disappeared after treatment with an AMPK inhibitor.

CONCLUSIONS

PMP protects against metabolic-stress-induced MASH through activating AMPK signaling, indicating that PMP may be a candidate for MASH therapy in the future.

Targeting glioblastoma with a brain-penetrant drug that impairs brain tumor stem cells via NLE1-Notch1 complex

Brain tumor stem cells (BTSCs) are a population of self-renewing malignant stem cells that play an important role in glioblastoma tumor hierarchy and contribute to tumor growth, therapeutic resistance, and tumor relapse. Thus, targeting of BTSCs within the bulk of tumors represents a crucial therapeutic strategy. Here, we report that edaravone is a potent drug that impairs BTSCs in glioblastoma. We show that edaravone inhibits the self-renewal and growth of BTSCs harboring a diverse range of oncogenic mutations without affecting non-oncogenic neural stem cells. Global gene expression analysis revealed that edaravone significantly alters BTSC transcriptome and attenuates the expression of a large panel of genes involved in cell cycle progression, stemness, and DNA repair mechanisms. Mechanistically, we discovered that edaravone directly targets Notchless homolog 1 (NLE1) and impairs Notch signaling pathway, alters the expression of stem cell markers, and sensitizes BTSC response to ionizing radiation (IR)-induced cell death. Importantly, we show that edaravone treatment in preclinical models delays glioblastoma tumorigenesis, sensitizes their response to IR, and prolongs the lifespan of animals. Our data suggest that repurposing of edaravone is a promising therapeutic strategy for patients with glioblastoma.

Edaravone administration and its potential association with a new clinical syndrome in cerebral infarction patients: Three case reports

BACKGROUND

Edaravone is a widely used treatment for patients with cerebral infarction and, in most cases, edaravone-induced side effects are mild. However, edaravone-related adverse reactions have been receiving increasing attention.

CASE SUMMARY

We treated three patients with acute cerebral infarction who died following treatment with edaravone. Edaravone is a widely used treatment for patients with cerebral infarction and, in most cases, edaravone-induced side effects are mild. However, edaravone-related adverse reactions have been receiving increasing attention.

CONCLUSION

Our cases highlight the importance of educating clinicians regarding the new edaravone-induced clinical syndromes of cerebral infarction as potentially fatal adverse drug reactions. Considering that no laboratory or confirmatory test exists to diagnose edaravone-induced death from cerebral infarction, clinicians’ knowledge is the key element in recognizing this phenomenon.

COMBINATION THERAPY WITH A SENSE OLIGONUCLEOTIDE TO INDUCIBLE NITRIC OXIDE SYNTHASE MRNA AND HUMAN SOLUBLE THROMBOMODULIN IMPROVES SURVIVAL OF SEPSIS MODEL RATS AFTER PARTIAL HEPATECTOMY

ABSTRACT

Sepsis after a major hepatectomy is a critical problem. In septic shock, the inflammatory mediator, nitric oxide (NO), is overproduced in hepatocytes and macrophages. The natural antisense (AS) transcripts, non-coding RNAs, are transcribed from a gene that encodes inducible nitric oxide synthase (iNOS). iNOS AS transcripts interact with and stabilize iNOS mRNAs. A single-stranded "sense oligonucleotide" (designated as SO1) corresponding to the iNOS mRNA sequence inhibits mRNA-AS transcript interactions and reduces iNOS mRNA levels in rat hepatocytes. In contrast, recombinant human soluble thrombomodulin (rTM) treats disseminated intravascular coagulopathy by suppressing coagulation, inflammation, and apoptosis. In this study, the combination therapy of SO1 and a low dose of rTM was evaluated for hepatoprotection in a rat septic shock model after partial hepatectomy. Rats underwent 70% hepatectomy, followed by intravenous (i.v.) injection of lipopolysaccharide (LPS) after 48 h. SO1 was injected (i.v.) simultaneously with LPS, whereas rTM was injected (i.v.) 1 h before LPS injection. Similarly to our previous report, SO1 increased survival after LPS injection. When rTM, which has different mechanisms of action, was combined with SO1, it did not interfere with the effect of SO1 and showed a significant increase in survival compared with LPS alone treatment. In serum, the combined treatment decreased NO levels. In the liver, the combined treatment inhibited iNOS mRNA and protein expression. A decreased iNOS AS transcript expression by the combined treatment was also observed. The combined treatment decreased mRNA expression of the inflammatory and pro-apoptotic genes while increasing that of the anti-apoptotic gene. Furthermore, the combined treatment reduced the number of myeloperoxidase-positive cells. These results suggested that the combination of SO1 and rTM has therapeutic potential for sepsis.

Omeprazole Increases Survival Through the Inhibition of Inflammatory Mediaters in Two Rat Sepsis Models

BACKGROUND

Omeprazole (OMZ) is a proton pump inhibitor that is used to reduce gastric acid secretion, but little is known about its possible liver protective effects. This study investigated whether OMZ has beneficial effects in rat septic models of LPS-induced liver injury after D-galactosamine (GalN) treatment and 70% hepatectomy (PH), and to determine the mechanisms of OMZ in an in vitro model of liver injury.

METHODS

In the in vivo models, the effects of OMZ were examined 1 h before treatments in both models on survival, nuclear factor (NF)-κB activation, histopathological analysis, and proinflammatory mediator expression in the liver and serum. In the in vitro model, primary cultured rat hepatocytes were treated with IL-1β in the presence or absence of OMZ. The influence of OMZ on nitric oxide (NO) product and inducible NO synthase (iNOS) induction and on the associated signaling pathway was analyzed.

RESULTS

OMZ increased survival and decreased tumor necrosis factor-alpha, iNOS, cytokine-induced neutrophil chemoattractant 1, IL-6, and IL-1β mRNA expression, and increased IL-10 mRNA expression in the livers of both GaIN/LPS- and PH/LPS-treated rats. Necrosis and apoptosis were inhibited by OMZ in GaIN/LPS rats, but OMZ had no effects on necrosis in PH/LPS rats. OMZ inhibited iNOS induction partially through suppression of NF-κB signaling in hepatocytes.

CONCLUSIONS

OMZ inhibited the induction of several inflammatory mediators, resulting in the prevention of LPS-induced liver injury after GalN liver failure and PH, although OMZ showed different doses and mechanisms in the two models.

Effect of Edaravone on MicroRNA Expression in Exosomes after Hepatic Ischemia-reperfusion Injury

BACKGROUND AND OBJECTIVE

Hepatic ischemia-reperfusion injury (HIRI) results in serious complications after liver resection and transplantation. Edaravone (ED) has a protective effect on IRI. This study was designed to evaluate whether ED could protect the liver of rats from HIRI injury and explored its exosomal miRNA-related mechanism.

METHODS

The sham group, hepatic ischemia/reperfusion (IR group), and hepatic ischemia/reperfusion + edaravone (ED group) models were established. We determined the protective effect of ED by measuring alanine aminotransferase (ALT), aspartate aminotransferase (AST), malondialdehyde (MDA), superoxide dismutase (SOD); enzyme-linked immunosorbent assay for tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β); hematoxylin-eosin staining and immunohistochemistry for histopathological changes. Exosomal miRNAs were subjected to second-generation sequencing to identify their differential expression. The results were analyzed using bioinformatics methods and validated using real-time quantitative polymerase chain reaction (RT-qPCR).

RESULTS

HIRI rats showed higher levels of ALT, AST, oxidative stress, and inflammatory markers; ED attenuated these effects. The sequencing results showed 6 upregulated and 13 downregulated miRNAs in the IR vs. sham groups, 10 upregulated and 10 downregulated miRNAs in the ED vs. IR groups. PC-3p-190-42101 was screened as an overlapping differentially expressed miRNA, and RT-qPCR validation showed that its expression in HIRI rats was significantly decreased; ED prevented this downregulation. Moreover, the expression of PC-3P-190-42101 was significantly correlated with the level of inflammatory factors.

CONCLUSION

These findings indicate that ED can regulate the level of inflammatory factors by affecting the expression of miRNA PC-3p-190-42101 in plasma exosomes to protect the liver from IRI.

Effect of edaravone on pregnant mice and their developing fetuses subjected to placental ischemia

Growing evidence indicates that reduced uterine perfusion pressure (RUPP) triggers the cascade of events leading to preeclampsia. Edaravone is a powerful free radical scavenger used for the treatment of ischemia/reperfusion diseases due to its anti-oxidative stress and anti-inflammatory properties. Here we investigate the effect of edaravone (3 mg/kg) on different maternal and fetal outcomes of RUPP-induced placental ischemia mice model. RUPP surgery was performed on gestation day (GD) 13 followed by edaravone injection from GD14 to GD18, sacrifice day. The results showed that edaravone injection significantly decreased the maternal blood pressure (113.2 ± 2.3 mmHg) compared with RUPP group (131.5 ± 1.9 mmHg). Edaravone increased fetal survival rate (75.4%) compared with RUPP group (54.4%), increased fetal length, weights, and feto-placental ratio (7.2 and 5.7 for RUPP and RUPP-Edaravone groups, respectively) compared with RUPP group. In addition, RUPP resulted in many fetal morphological abnormalities as well as severe delayed ossification, however edaravone decreased the morphological abnormalities and increased the ossification of the fetal endoskeleton. Edaravone improved the histopathological structure of the maternal kidney and heart as well as decreased the elevated blood urea and creatinine levels (31.5 ± 0.15 mg/dl (RUPP), 25.6 ± 0.1 mg/dl (RUPP+edaravone) for urea and 5.4 ± 0.1 mg/dl (RUPP), 3.5 ± 0.1 mg/dl (RUPP+edaravone) for creatinine) and decreased cleaved caspase-3 expression in the maternal kidney. In conclusion, this study demonstrated that our RUPP mice model recapitulated preeclampsia symptoms and edaravone injection ameliorated most of these abnormalities suggesting its effectiveness and potential application in preeclampsia treatment regimes.

The Proton Pump Inhibitor Lansoprazole Has Hepatoprotective Effects in In Vitro and In Vivo Rat Models of Acute Liver Injury

BACKGROUND/AIMS

The proton pump inhibitor lansoprazole (LPZ) is clinically used to reduce gastric acid secretion, but little is known about its possible hepatoprotective effects. This study aimed to investigate the hepatoprotective effects of LPZ and its potential mechanisms using in vitro and in vivo rat models of liver injury.

METHODS

For the in vitro model of liver injury, primary cultured rat hepatocytes were treated with interleukin-1β in the presence or absence of LPZ. The influence of LPZ on inducible nitric oxide synthase (iNOS) induction and nitric oxide (NO) production and on the associated signaling pathways was analyzed. For the in vivo model, rats were treated with D-galactosamine (GalN) and lipopolysaccharide (LPS). The effects of LPZ on survival and proinflammatory mediator expression (including iNOS and tumor necrosis factor-α) in these rats were examined.

RESULTS

LPZ inhibited iNOS induction partially through suppression of the nuclear factor-kappa B signaling pathway in hepatocytes, thereby reducing potential liver injury from excessive NO levels. Additionally, LPZ increased survival by 50% and decreased iNOS, tumor necrosis factor-α, and cytokine-induced neutrophil chemoattractant-1 mRNA expression in the livers of GalN/LPS-treated rats. LPZ also inhibited nuclear factor-kappa B activation by GalN/LPS.

CONCLUSIONS

LPZ inhibits the induction of several inflammatory mediators (including cytokines, chemokines, and NO) partially through suppression of nuclear factor-kappa B, resulting in the prevention of fulminant liver failure. The therapeutic potential of LPZ for liver injuries warrants further investigation.

Levosimendan pretreatment improves survival of septic rats after partial hepatectomy and suppresses iNOS induction in cytokine-stimulated hepatocytes

We evaluated the survival effects and biochemical profiles of levosimendan in septic rats after partial hepatectomy and investigated its effects in cultured hepatocytes. Thirty-two rats underwent 70% hepatectomy and were randomised equally into four groups, followed by lipopolysaccharide (LPS) injection (250 µg/kg, i.v.) after 48 h. Levosimendan was given (i.p.) 1 h before LPS injection [group (A) levosimendan 2 mg/kg; (B) 1; (C) 0.5; (D) vehicle]. Survival at 7 days was increased significantly in group A compared with that in group D [A: 63%; B: 38%; C: 13%; D: 0%]. In serum, levosimendan decreased the level of tumour necrosis factor-α, interleukin (IL)-1β, IL-6 and nitric oxide (NO). In remnant livers, levosimendan inhibited inducible nitric oxide synthase (iNOS) gene expression. In primary cultured rat hepatocytes stimulated by IL-1β, levosimendan suppressed NO production by inhibiting iNOS promoter activity and stability of its mRNA.

Protective Effect of the Total Triterpenes of Euscaphis konishii Hayata Pericarp on Bacillus Calmette-Guérin Plus Lipopolysaccharide-Induced Liver Injury

BACKGROUND

Liver injury has been recognized as a primary cause of hepatic morbidity and mortality. Euscaphis konishii Hayata, also called Euscaphis fukienensis Hsu, is usually used as a detumescent and analgesic agent to improve liver function in South China, but its mechanism of action and chemical composition are unclear.

OBJECTIVE

The main aim of the study was to investigate the constituent and potential hepatoprotective mechanism of the total triterpenes of E. konishii pericarp (TTEP).

METHODS

The constituent of TTEP was analyzed by a series of silica gel column to get single compounds and then identified by NMR and MS. In vitro assays were conducted to test the free radical scavenging activity of TTEP. The BCG/LPS-induced immunological livery injury mice model was established to clarify the hepatoprotective effect of TTEP in vivo.

RESULTS

8 pentacyclic triterpene acids were separated and identified by NMR and MS. TTEP treatment (50, 100, and 200 mg/Kg) improved the immune function of the BCG/LPS-infected mice, dose-dependently alleviated the BCG/LPS-induced inflammation and oxidative stress, and ameliorated the hepatocyte apoptosis in the liver tissue.

CONCLUSION

The pericarp of E. konishii may be further considered as a potent natural food for liver disease treatment.

Bone marrow-derived mesenchymal stem cells ameliorate liver injury in a rat model of sepsis by activating Nrf2 signaling

Sepsis is a fatal condition that leads to serious systemic inflammation and multiple organ dysfunction syndromes. This study was designed to investigate the possible therapeutic effect of bone marrow-derived mesenchymal stem cells (BMSCs) on sepsis-induced liver injury. We also aimed to examine the role of Nrf2 activation in modulating the response to sepsis following BMSCs treatment. Twenty-four adult male albino rats were assigned to: control, lipopolysaccharide (LPS) and LPS-stem cell groups. Liver samples were processed for light and electron microscope examinations. Immunohistochemical localization of BAX, proliferating cell nuclear antigen and nuclear factor-erythroid 2-related factor 2 (Nrf2) was carried out. Liver homogenates were prepared for assessment of reduced glutathione, glutathione peroxidase, tumor necrosis factor-alpha and interleukin-6 and also real-time PCR analysis of Nrf2 expression. BMSCs treatment improved the histopathological changes of the liver, enhanced tissue regeneration and decreased apoptosis following sepsis. We reported highly significant enhancement in Nrf2 expressions at mRNA and protein levels in the LPS-stem cell group compared with the LPS group. The up regulation of Nrf2 was probably implicated in decreasing inflammatory cytokine levels and counteracting oxidative stress induced by sepsis. Thus, BMSCs therapies could be a viable approach to treat sepsis-induced liver damage by activating Nrf2 signaling.

A sense oligonucleotide to inducible nitric oxide synthase mRNA increases the survival rate of rats in septic shock

Natural antisense transcripts (asRNAs) that do not encode proteins are transcribed from rat, mouse, and human genes, encoding inducible nitric oxide synthase (iNOS), which catalyzes the production of the inflammatory mediator nitric oxide (NO). In septic shock, NO is excessively produced in hepatocytes and macrophages. The iNOS asRNA interacts with and stabilizes iNOS mRNA. We found that single-stranded 'sense' oligonucleotides corresponding to the iNOS mRNA sequence reduced iNOS mRNA levels by interfering with the mRNA-asRNA interactions in rat hepatocytes. The iNOS sense oligonucleotides that were substituted with phosphorothioate bonds and locked nucleic acids efficiently decreased the levels of iNOS mRNA and iNOS protein. In this study, the gene expression patterns in the livers of two endotoxemia model rats with acute liver failure were compared. Next, we optimized the sequence and modification of the iNOS sense oligonucleotides in interleukin 1β-treated rat hepatocytes. When a sense oligonucleotide was simultaneously administered with d-galactosamine and bacterial lipopolysaccharide (LPS) to rats, their survival rate significantly increased compared to the rats administered d-galactosamine and LPS alone. In the livers of the sense oligonucleotide-administered rats, apoptosis in the hepatocytes markedly decreased. These results suggest that natural antisense transcript-targeted regulation technology using iNOS sense oligonucleotides may be used to treat human inflammatory diseases, such as sepsis and septic shock.

Elental® amino acid component has protective effects on primary cultured hepatocytes and a rat model of acute liver injury

Amino acids can exert protective effects on the liver either when administered as a medication or following an operation. In this study, we examined the protective effects of amino acids on the liver using in vitro and in vivo models by studying their influence on the induction of inducible nitric oxide synthase (iNOS) and nitric oxide production as a liver injury marker in cultured hepatocytes and liver-protective effects in d-galactosamine and lipopolysaccharide (GalN/LPS)-treated rats, respectively. Primary cultured rat hepatocytes were treated with interleukin (IL)-1β in the presence or absence of Elental® amino acid component (EleAA; 17 amino acids). Rats were pretreated with either EleAA or a diet containing selected amino acids followed by GalN/LPS injection. Survival rate and mRNA expression were analyzed. EleAA inhibited iNOS induction through reduction of mRNA synthesis and stability in cultured hepatocytes, indicating prevention of liver injury, but did not show a liver-protective effect in GalN/LPS rats. Among EleAA, Lys, Trp, His, and Arg (4AA) markedly decreased nitric oxide production and inhibited nuclear factor-κB (NF-κB) activation. In GalN/LPS rats, 4AA (3% of each amino acid in diet) increased survival rate by 50% and decreased mRNA expression of iNOS, tumor necrosis factor-α, and cytokine-induced neutrophil chemoattractant-1 in the liver. 4AA reduced NF-κB activation induced by GalN/LPS. 4AA inhibited the expression of inflammatory mediators, in part through inhibition of NF-κB activation in cultured hepatocytes and GalN/LPS-treated rats. The results suggest that EleAA has therapeutic potential for organ injuries including liver.

Edaravone enhances the viability of ischemia/reperfusion flaps

The purpose of the experiment was to study the efficacy of edaravone in enhancing flap viability after ischemia/reperfusion (IR) and its mechanism. Forty-eight adult male SD rats were randomly divided into 3 groups: control group (n=16), IR group (n=16), and edaravone-treated IR group (n=16). An island flap at left lower abdomen (6.0 cm×3.0 cm in size), fed by the superficial epigastric artery and vein, was created in each rat of all the three groups. The arterial blood flow of flaps in IR group and edaravone-treated IR group was blocked for 10 h, and then the blood perfusion was restored. From 15 min before reperfusion, rats in the edaravone-treated IR group were intraperitoneally injected with edaravone (10 mg/kg), once every 12 h, for 3 days. Rats in the IR group and control group were intraperitoneally injected with saline, with the same method and frequency as the rats in the edaravone-treated IR group. In IR group and edaravone-treated IR group, samples of flaps were harvested after reperfusion of the flaps for 24 h. In the control group, samples of flaps were harvested 34 h after creation of the flaps. The content of malondialdehyde (MDA) and activity of superoxide dismutase (SOD) were determined, and changes in organizational structure and infiltration of inflammatory cells were observed by hematoxylin-eosin (HE) staining, apoptotic cells of vascular wall were marked by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, and the apoptotic rate of cells in vascular wall was calculated. The ultrastructural changes of vascular endothelial cells were observed by transmission electron microscopy (TEM). Seven days after the operation, we calculated the flap viability of each group, and marked vessels of flaps by immunohistochemical staining for calculating the average number of subcutaneous vessels. The results showed that the content of MDA, the number of multicore inflammatory cells and apoptotic rate of cells in vascular wall in the edaravone-treated IR group were significantly lower than those in the IR group. The activity of SOD, flap viability and average number of subcutaneous vessels in the edaravone-treated IR group were significantly higher than those in the IR group. All the differences were statistically significant. The ultrastructure injury of vascular endothelial cells in the edaravone-treated IR group was slighter than that in IR group. It was concluded that edaravone can significantly enhance IR flap viability and protect flap vessels, which is related to scavenging oxygen free radicals, reducing the consumption of SOD, reducing the extent of lipid peroxidation and inflammation, and protecting functional structure of vessels in the early stages of reperfusion.

Redox therapy in neonatal sepsis: reasons, targets, strategy, and agents

Neonatal sepsis is one of the most fulminating conditions in neonatal intensive care units. Antipathogen and supportive care are administered routinely, but do not deliver satisfactory results. In addition, the efforts to treat neonatal sepsis with anti-inflammatory agents have generally shown to be futile. The accumulating data imply that intracellular redox changes intertwined into neonatal sepsis redox cycle represent the main cause of dysfunction of mitochondria and cells in neonatal sepsis. Our aim here is to support the new philosophy in neonatal sepsis treatment, which involves the integration of mechanisms that are responsible for cellular dysfunction and organ failure, the recognition of the most important targets, and the selection of safe agents that can stop the neonatal sepsis redox cycle by hitting the hot spots. Redox-active agents that could be beneficial for neonatal sepsis treatment according to these criteria include lactoferrin, interleukin 10, zinc and selenium supplements, ibuprofen, edaravone, and pentoxifylline.

Involvement of Cytochrome P450 in Reactive Oxygen Species Formation and Cancer

This review examines the involvement of cytochrome P450 (CYP) enzymes in the formation of reactive oxygen species in biological systems and discusses the possible involvement of reactive oxygen species and CYP enzymes in cancer. Reactive oxygen species are formed in biological systems as byproducts of the reduction of molecular oxygen and include the superoxide radical anion (∙O2-), hydrogen peroxide (H2O2), hydroxyl radical (∙OH), hydroperoxyl radical (HOO∙), singlet oxygen ((1)O2), and peroxyl radical (ROO∙). Two endogenous sources of reactive oxygen species are the mammalian CYP-dependent microsomal electron transport system and the mitochondrial electron transport chain. CYP enzymes catalyze the oxygenation of an organic substrate and the simultaneous reduction of molecular oxygen. If the transfer of oxygen to a substrate is not tightly controlled, uncoupling occurs and leads to the formation of reactive oxygen species. Reactive oxygen species are capable of causing oxidative damage to cellular membranes and macromolecules that can lead to the development of human diseases such as cancer. In normal cells, intracellular levels of reactive oxygen species are maintained in balance with intracellular biochemical antioxidants to prevent cellular damage. Oxidative stress occurs when this critical balance is disrupted. Topics covered in this review include the role of reactive oxygen species in intracellular cell signaling and the relationship between CYP enzymes and cancer. Outlines of CYP expression in neoplastic tissues, CYP enzyme polymorphism and cancer risk, CYP enzymes in cancer therapy and the metabolic activation of chemical procarcinogens by CYP enzymes are also provided.

pyroGlu-Leu inhibits the induction of inducible nitric oxide synthase in interleukin-1β-stimulated primary cultured rat hepatocytes

Pyroglutamyl leucine (pyroGlu-Leu), which is a peptide isolated from wheat gluten hydrolysate, has been reported to be a hepatoprotective compound in acute liver failure. In inflamed liver, proinflammatory cytokines including interleukin (IL)-1β and tumor necrosis factor (TNF)-α stimulate the induction of inducible nitric oxide synthase (iNOS). Excess production of nitric oxide (NO) by iNOS is an inflammatory biomarker in liver injury. We examined proinflammatory cytokine-stimulated hepatocytes as a simple "in vitro inflammation model" to determine liver protective effects of pyroGlu-Leu and its mechanisms of action. We hypothesized that pyroGlu-Leu inhibits the induction of iNOS gene expression, resulting in the attenuation of hepatic inflammation. Hepatocytes were isolated from rats by collagenase perfusion and cultured. Primary cultured cells were treated with IL-1β in the presence or absence of pyroGlu-Leu. The induction of iNOS and its signaling pathway were analyzed. IL-1β stimulated the enhancement of NO production in hepatocytes and this effect was inhibited by pyroGlu-Leu. pyroGlu-Leu decreased the expression of iNOS protein and its mRNA. Transfection experiments with iNOS-luciferase constructs revealed that pyroGlu-Leu inhibited both of iNOS promoter transactivation and its mRNA stabilization. pyroGlu-Leu also decreased the expression of an iNOS gene antisense transcript, which is involved in iNOS mRNA stability. However, pyroGlu-Leu had no effects on IκB degradation and NF-κB activation. Results demonstrate that pyroGlu-Leu inhibited the induction of iNOS gene expression at transcriptional and post-transcriptional steps through IκB/NF-κB-independent pathway, leading to the prevention of NO production. pyroGlu-Leu may have therapeutic potential for liver injury through the suppression of iNOS.

The mechanism of hepatoprotective effect of sesquiterpene rich fraction from Cichorum glandulosum Boiss. et Huet on immune reaction-induced liver injury in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Cichorum glandulosum Boiss. et Huet is a traditional Uygur herbal medicine that has been used as a cholagogic and diuretic agent to improve liver function. However, the mechanism is not known for the liver-protective function. We investigated the antioxidant effects of plant extraction (CGE60) in vitro and in vivo, and find the mechanism of liver protection in Bacille Calmette-Guerin vaccine (BCG)+Lipopolysaccharides (LPS) induced liver injury in mice.

MATERIALS AND METHODS

CGE60 was made, and the antioxidant activity was investigated by comparing the ability of scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH), and 2,2-azinobis(3-ehtylbenzothiazolin-6-sulfnicAcid) diammonium salt (ABTS) free radicals in vitro. Then, CGE60 was administrated in mice of liver damage model which was induced in mice using the BCG+LPS protocol. The CGE 60 extract was tested at three dosages: 50 mg/kg, 100 mg/kg, and 200 mg/kg. Product of lipid peroxidation (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-PX,), nitric oxide (NO), nitric oxide synthetase (NOS), hydroxyproline and alkaline phosphatase (ALP) contents were evaluated in liver to determine the CGE60 activity in the hepatic injury model. Tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and transforming growth factor-β (TGF-β) proteins were determined in the liver tissues using ELSIA. The signaling activities were evaluated in Western blot.

RESULTS

CGE60 exhibited strong antioxidant ability in vitro. With oral administration, CGE60 significantly increased the activity of CAT, SOD, GSH-PX, and decreased the level of NO, NO synthase, hydroxyproline, ALP and lipid peroxidation liver of in the BDG+ LPS model. CGE60 attenuated hepatic inflammation via down- regulation of TNF-α, IL-6 and TGF-β. CGE60 blocked protein expression of cytochrome P450 2E1 (CYP2E1), nuclear factor kappa-B (NF-κB), phosphorylation of extracellular signal-regulated kinase (p-ERK1/2), and cyclooxygenase-2 (COX-2),but activated the expression of p-P38 MAPK.

CONCLUSION

This study suggests that CGE60 possesses antioxidant activity and this activity associates with hepatoprotective effect in the mice of BCG +LPS model, and the mechanisms underlying these effects may involve antioxidant actions and anti-inflammation activities.

Butyrate protects rat liver against total hepatic ischemia reperfusion injury with bowel congestion

Hepatic ischemia/reperfusion (I/R) injury is an unavoidable consequence of major liver surgery, especially in liver transplantation with bowel congestion, during which endotoxemia is often evident. The inflammatory response aggravated by endotoxin after I/R contributes to liver dysfunction and failure. The purpose of the present study was to investigate the protective effect of butyrate, a naturally occurring four-carbon fatty acid in the body and a dietary component of foods such as cheese and butter, on hepatic injury complicated by enterogenous endotoxin, as well as to examine the underlying mechanisms involved. SD rats were subjected to a total hepatic ischemia for 30 min after pretreatment with either vehicle or butyrate, followed by 6 h and 24 h of reperfusion. Butyrate preconditioning markedly improved hepatic function and histology, as indicated by reduced transaminase levels and ameliorated tissue pathological changes. The inflammatory factors levels, macrophages activation, TLR4 expression, and neutrophil infiltration in live were attenuated by butyrate. Butyrate also maintained the intestinal barrier structures, reversed the aberrant expression of ZO-1, and decreased the endotoxin translocation. We conclude that butyrate inhibition of endotoxin translocation, macrophages activation, inflammatory factors production, and neutrophil infiltration is involved in the alleviation of total hepatic I/R liver injury in rats. This suggests that butyrate should potentially be utilized in liver transplantation.

Hydrogen-rich saline attenuates postoperative liver failure after major hepatectomy in rats

BACKGROUND/AIMS

A major hepatectomy occasionally lead to acute liver failure and death. We demonstrated the anti-oxidative and anti-inflammatory effects and functional mechanisms of hydrogen-rich saline (HS), a novel antioxidant, on an experimental model of rats after a partial hepatectomy (PH).

METHODS

The rats underwent a 90% hepatectomy. HS was given intraperitoneally after the operation and every 8hours after.

RESULTS

HS markedly improved the survival rate of two experimental groups after the massive hepatectomy and inhibited increases in serum levels of TBIL, DBIL, ALT and AST. The histopathological analysis demonstrated that HS attenuated inflammatory changes in the liver. HS administration markedly lowered the massive hepatectomy induced elevation of the serum hyaluronic acid (HA) concentrations. HS inhibited the formation of one of the markers of oxidative damage, malondialdehyde (MDA), and increased the activities of superoxide dismutase (SOD) in liver tissue. In the HS-treated group, increases in inflammatory cytokines, such as TNF-α, IL-6 and HMGB-1, were inhibited in the liver tissue. The NF-κB p65 staining revealed that HS inhibited the activation of the transcription factor nuclear factor kappa B (NF-kB).

CONCLUSIONS

HS attenuates the massive hepatectomy induced liver injury not only by attenuating oxidative damage, but also by reducing the production of inflammatory cytokines, such as TNF-α, IL-6 and HMGB-1, in part through the inhibition of NF-kB activation.

Interleukin-1β induces tumor necrosis factor-α secretion from rat hepatocytes

AIM

Tumor necrosis factor-α (TNF-α) is a pleiotropic cytokine involved in various inflammatory diseases. The only production of TNF-α in the liver is thought to be from hepatic macrophages known as Kupffer cells, predominantly in response to bacterial lipopolysaccharide (LPS).

METHODS

Primary cultured rat hepatocytes were used to analyze TNF-α expression in response to the pro-inflammatory cytokine, interleukin-1β (IL-1β). Livers of rats subjected to LPS-induced endotoxemia were analyzed.

RESULTS

Immunocytochemistry and enzyme-linked immunosorbent assays demonstrated that IL-1β-treated rat hepatocytes secreted TNF-α, and RNA analyses indicated that TNF-α mRNA was induced specifically by IL-1β. Northern blot analysis showed that not only mRNA, but also a natural antisense transcript (asRNA), was transcribed from the rat Tnf gene in IL-1β-treated hepatocytes. TNF-α was detected in the hepatocytes of LPS-treated rats. Both TNF-α mRNA and asRNA were expressed in the hepatocytes of LPS-treated rats, human hepatocellular carcinoma and human monocyte/macrophage cells. To disrupt the interaction between TNF-α asRNA and TNF-α mRNA, sense oligonucleotides corresponding to TNF-α mRNA were introduced into rat hepatocytes resulting in significantly increased levels of TNF-α mRNA. One of these sense oligonucleotides increased a half-life of TNF-α mRNA, suggesting that the TNF-α asRNA may reduce the stability of TNF-α mRNA.

CONCLUSION

IL-1β-stimulated rat hepatocytes are a newly identified source of TNF-α in the liver. TNF-α mRNA and asRNA are expressed in rats and humans, and the TNF-α asRNA reduces the stability of the TNF-α mRNA. Hepatocytes and TNF-α asRNA may be therapeutic targets to regulate levels of TNF-α mRNA.

Beneficial effects of green tea catechin on massive hepatectomy model in rats

BACKGROUND

Green tea catechin, especially epigallocatechin gallate (EGCG), is a well-known scavenger of reactive oxygen species and it may also function as an antioxidant through modulation of transcriptional factors and enzyme activities.

METHODS

Green tea extract (GTE®) which contained numerous EGCG was used. Wistar rats were performed 90 % hepatectomy and classified into 2 groups with (GTEHx, n = 25) or without GTE treatment (Hx, n = 25) and sacrificed at 1, 3, 7 and 14 days after operations. All rats had free access to drinking water supplemented with or without GTE from the 7th pre-operative day. Liver regeneration, hepatic inducible nitric oxide synthase (iNOS), anti-oxidative enzymes [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px)] and inflammatory markers [cyclooxygenase-2 (COX-2), nuclear factor kappa B (NFκB), tumor necrosis factor-α (TNF-α)] were investigated.

RESULTS

The liver weight to body weight ratio (p < 0.01), proliferating cell nuclear antigen labeling index (p < 0.05) and phosphorylated extracellular signal-regulated kinase 1/2 (p < 0.05) at day 1 in the GTEHx group significantly increased compared to the Hx group. Hepatic iNOS levels at day 1 significantly decreased (p < 0.01) in the GTEHx group. Hepatic SOD, CAT and GSH-Px levels at day 1 significantly increased (SOD: p < 0.01, CAT and GSH-Px: p < 0.05) in the GTEHx group. In contrast, COX-2, NFκB and TNF-α levels at day 1 significantly decreased (COX-2: p < 0.01, NFκB and TNF-α: p < 0.05) in the GTEHx group.

CONCLUSIONS

GTE pretreatment stimulated liver regeneration and improved liver damage after massive hepatectomy through anti-oxidative and anti-inflammatory effects. Green tea catechin might have the potential to attenuate liver dysfunction in early stage after massive hepatectomy.

Edaravone protects endotoxin-induced liver injury by inhibiting apoptosis and reducing proinflammatory cytokines

Studies have shown that edaravone may prevent liver injury. This study aimed to investigate the effects of edaravone on the liver injury induced by D-galactosamine (GalN) and lipopolysaccharide (LPS) in female BALB/c mice. Edaravone was injected into mice 30 min before and 4 h after GalN/LPS injection. The survival rate was determined within the first 24 h. Animals were killed 8 h after GalN/LPS injection, and liver injury was biochemically and histologically assessed. Hepatocyte apoptosis was measured by TUNEL staining; proinflammatory cytokines [tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6)] in the liver were assayed by ELISA; expression of caspase-8 and caspase-3 proteins was detected by Western blot assay; and caspase-3 activity was also determined. Results showed that GalN/LPS induced marked elevations in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Edaravone significantly inhibited elevation of serum AST and ALT, accompanied by an improvement in histological findings. Edaravone lowered the levels of TNF-α and IL-6 and reduced the number of TUNEL-positive cells. In addition, 24 h after edaravone treatment, caspase-3 activity and mortality were reduced. Edaravone may effectively ameliorate GalN/LPS-induced liver injury in mice by reducing proinflammatory cytokines and inhibiting apoptosis.

The alteration of copper homeostasis in inflammation induced by lipopolysaccharides

Significant changes of copper homeostasis were triggered by lipopolysaccharides, which result in systemic inflammatory response and contribute to hepatic injury. Administration of lipopolysaccharides resulted in the increase of plasma "free" copper and total copper concentrations, whereas, the decrease of "free" copper and total copper contents in liver tissue. Copper-associated proteins were detected and showed a down-regulation of X-linked inhibitor of apoptosis protein, and up-regulation of copper metabolism domain containing 1 and copper transporter 1. The alteration of these proteins would lower the apoptotic threshold. Meanwhile, the increasing of circulation copper might cause oxidative injury through Fenton reaction and contribute to tissue injury. Our findings underscored the possibility that these changes in systemic copper homeostasis might provide a novel insight of the characteristic of the acute phase of inflammatory response and the underlying influence on tissue injury.

Fluvastatin inhibits the induction of inducible nitric oxide synthase, an inflammatory biomarker, in hepatocytes

AIM

Statins (3-hydroxy-3-methylglutaryl coenzyme A [HMG-CoA] reductase inhibitors), which were originally designed to lower plasma cholesterol levels, are increasingly recognized as anti-inflammatory agents. In the inflamed liver, pro-inflammatory cytokines stimulate the induction of inducible nitric oxide synthase (iNOS). Overproduction of NO by iNOS has been implicated as a factor in liver injury. We examined pro-inflammatory cytokine-stimulated hepatocytes as a simple in vitro injury model to determine liver-protective effects of statins. We hypothesized that statins are involved in the downregulation of iNOS, resulting in decreased hepatic inflammation.

METHODS

Hepatocytes were isolated from rats by collagenase perfusion and centrifugation. Primary cultured hepatocytes were treated with interleukin (IL)-1β in the presence or absence of fluvastatin. The induction of iNOS and its signaling pathway were analyzed.

RESULTS

IL-1β produced increased levels of NO. This effect was inhibited by fluvastatin, which exerted its maximal effects at 100 μM. Fluvastatin decreased the levels of iNOS protein and its mRNA expression. Fluvastatin had no effects on IκB degradation and nuclear factor-κB activation. However, fluvastatin inhibited the upregulation of type I IL-1 receptor mRNA and protein expression. Transfection experiments demonstrated that fluvastatin suppressed iNOS induction by the inhibition of promoter transactivation and mRNA stabilization. Fluvastatin reduced the expression of an iNOS gene antisense-transcript, which is involved in iNOS mRNA stability.

CONCLUSION

Results indicate that fluvastatin inhibits the induction of iNOS at both transcriptional and post-transcriptional steps, leading to the prevention of NO production. Fluvastatin may provide therapeutic potential in iNOS induction involved in various liver injuries.

Carnosic acid attenuates lipopolysaccharide-induced liver injury in rats via fortifying cellular antioxidant defense system

The study investigated the protective effects of carnosic acid (CA), the principal constituent of rosemary, on lipopolysaccharide (LPS)-induced oxidative/nitrosative stress and hepatotoxicity in rats. CA was administered orally to rats at doses of 15, 30 and 60 mg/kg body weight before LPS challenge (single intraperitoneal injection, 1 mg/kg body weight). The results revealed that CA inhibited LPS-induced liver damage and disorder of lipid metabolism, which were mainly evidenced by decreased serum levels of alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase. CA also inhibited LPS-induced oxidative/nitrosative stress by decreasing lipid peroxidation, protein carbonylation, and serum levels of nitric oxide. Histopathological examination demonstrated that CA could improve pathological abnormalities and reduce the immigration of inflammatory cells in liver tissues with LPS challenge. Concurrently, CA potently inhibited the LPS-induced rise in serum levels of the pro-inflammatory cytokines tumor necrosis factor-α and interleukin-6. CA supplementation markedly enhanced the body's cellular antioxidant defense system by restoring the levels of superoxide dismutase, glutathione peroxidase, and glutathione in serum and liver after the LPS challenge. In conclusion, the present study suggests that CA successfully and dose dependently attenuates LPS-induced hepatotoxicity possibly by preventing cytotoxic effects of oxygen free radicals, NO and cytokines.

alpha-lipoic acid prevents the induction of iNOS gene expression through destabilization of its mRNA in proinflammatory cytokine-stimulated hepatocytes

BACKGROUND/AIMS

α-Lipoic acid (α-LA) has been reported to reduce ischemia-reperfusion injury (IRI). Proinflammatory cytokines stimulate the induction of inducible nitric oxide synthase (iNOS) gene expression, leading to excess production of NO and resulting in liver injury including IRI. We hypothesized that inhibition of iNOS induction underlies the protective effects of α-LA on the liver. The objective was to investigate whether α-LA directly influences iNOS induction in cultured hepatocytes, which is used as a simple in vitro injury model, and the mechanism involved.

METHODS

Primary cultured rat hepatocytes were treated with interleukin (IL)-1β in the presence or absence of α-LA. The induction of iNOS and NO production and its signal were analyzed.

RESULTS

α-LA inhibited the expression of iNOS mRNA and protein dose- and time-dependently, resulting in decreases in NO production. α-LA had no effects on the degradation of IκB proteins and activation of NF-κB. In contrast, α-LA inhibited the upregulation of type I IL-1 receptor stimulated by IL-1β, although α-LA had no effect on Akt activation. Transfection experiments with iNOS promoter-luciferase constructs revealed that α-LA had no effect on the transactivation of the iNOS promoter, but decreased the stabilization of iNOS mRNA. Further, α-LA inhibited the expression of an iNOS gene antisense-transcript, which is involved in iNOS mRNA stability.

CONCLUSIONS

Results indicate that α-LA inhibits the induction of iNOS gene expression at a posttranscriptional step via iNOS mRNA stabilization, rather than promoter activation. It may provide useful therapeutic effects through the suppression of iNOS induction involved in liver injury.

Protective effects of ulinastatin on pulmonary damage in rats following scald injury

Organ protection is desirable in severe burn/scald injuries, and damage mechanisms and thus effective therapies following scald injury have not been fully elucidated. Our aim was to examine the beneficial effects of ulinastatin on pulmonary damage associated with scald injury. Lewis rats were subjected to 30% total body surface area (TBSA) scald injury and were randomly divided into a burn control (S group) and an ulinastatin-treated group (U group). Lung malondialdehyde (MDA) and superoxide dismutase (SOD) levels were determined, and the lungs were examined histologically with immunohistochemistry (IHC) as well for the major histocompatibility complex (MHC) class I chain-related antigen A (MICA) and Bcl-2 at 24, 48 and 72 h after the injury. The expression of spleen human leucocyte antigen-DR (HLA-DR) was detected by immunohistochemistry analysis. Selectins and adhesion molecules in lungs and serum were also detected. The lung injury degree was represented as wet/dry (W/D) values and alveolar thickness. Ulinastatin decreased MDA levels and ameliorated the down-regulation of SOD activity. MICA was up-regulated after the scald, and this up-regulation was greatly diminished by ulinastatin. Bcl-2 was up-regulated after the scald, especially in the U group. The spleen HLA-DR expression demonstrated the immunoregulatory effects of ulinastatin, which effectively protected the pulmonary tissues from scald-induced injury. Our results demonstrated that pulmonary damage was associated with autoimmunity and oxidant attack after severe scald. Ulinastatin exhibits significant protective effects on these effects.

Japanese herbal medicine, inchinkoto, inhibits inducible nitric oxide synthase induction in interleukin-1β-stimulated hepatocytes

AIM

  A herbal medicine, kampo inchinkoto (TJ-135), is used to treat jaundice and liver fibrosis in patients with cirrhosis. In the inflamed liver, proinflammatory cytokines stimulate the induction of inducible nitric oxide synthase (iNOS) gene expression. Over-production of nitric oxide (NO) by iNOS has been implicated as a factor in liver injury. We examined interleukin (IL)-1β-stimulated hepatocytes as a simple in vitro injury model to determine liver-protective effects of TJ-135. The objective was to investigate whether TJ-135 influences iNOS induction and to determine its mechanism.

METHODS

  Primary cultured rat hepatocytes were treated with IL-1β in the presence or absence of TJ-135. The induction of iNOS and its signaling pathway were analyzed.

RESULTS

  IL-1β produced increased levels of NO. This effect was inhibited by TJ-135, which exerted its maximal effects at 3 mg/mL. TJ-135 decreased the levels of iNOS protein and its mRNA expression. Experiments with nuclear extracts revealed that TJ-135 inhibited the translocation of nuclear factor-κB (NF-κB) to the nucleus and its DNA binding. TJ-135 also inhibited the activation of Akt, resulting in the reduction of type I IL-1 receptor mRNA and protein expression. Transfection experiments with iNOS promoter-luciferase constructs demonstrated that TJ-135 suppressed iNOS induction by inhibition of promoter transactivation and mRNA stabilization. TJ-135 reduced the expression of an iNOS gene antisense-transcript. Delayed administration or withdrawal of TJ-135 after IL-1β addition also inhibited iNOS induction.

CONCLUSIONS

  RESULTS indicate that TJ-135 inhibits the induction of iNOS at both transcriptional and post-transcriptional steps, leading to the prevention of NO production. TJ-135 may have therapeutic potential for various liver injuries through the suppression of iNOS induction.

Active hexose correlated compound inhibits the expression of proinflammatory biomarker iNOS in hepatocytes

BACKGROUND/AIMS

Excess production of nitric oxide (NO) by inducible nitric oxide synthase (iNOS) has been implicated as proinflammatory biomarker in liver injury. The application of active hexose correlated compound (AHCC) as a functional food in complementary and alternative medicine has increased. The possibility that AHCC might inhibit iNOS induction was investigated as a potential liver-protective effect.

METHODS

Hepatocytes were isolated from rats by collagenase perfusion and cultured. Primary cultured hepatocytes were treated with interleukin-1β in the presence or absence of AHCC-sugar fraction (AHCC-SF).

RESULTS AND CONCLUSION

AHCC-SF inhibited the production of NO and reduced expressions of iNOS mRNA and its protein. AHCC-SF had no effects on either IκB degradation or nuclear factor-κB (NF-κB) activation. In contrast, AHCC-SF inhibited the upregulation of type I interleukin-1 receptor (IL-1RI) through the inhibition of Akt phosphorylation. Transfection experiments with iNOS promoter-luciferase constructs revealed that AHCC-SF reduced the levels of iNOS mRNA at both promoter transactivation and mRNA stabilization steps. AHCC-SF inhibited the expression of iNOS gene antisense transcript, which is involved in iNOS mRNA stabilization. These findings demonstrate that AHCC-SF suppresses iNOS gene expression through a IκB/NF-κB-independent but Akt/IL-1RI-dependent pathway, resulting in the reduction of NO production. AHCC-SF may have therapeutic potential for various liver injuries.

Beyond free radical scavenging: Beneficial effects of edaravone (Radicut) in various diseases (Review)

Free radicals play an important role in the pathogenesis of a variety of diseases; thus, they are an attractive target for therapeutic intervention in these diseases. Compounds capable of scavenging free radicals have been developed for this purpose and some, developed for the treatment of cerebral ischemic stroke, have progressed to clinical trials. One such scavenger, edaravone, is used to treat patients within 24 h of stroke. Edaravone, which can diffuse into many disease-affected organs, also shows protective effects in the heart, lung, intestine, liver, pancreas, kidney, bladder and testis. As well as scavenging free radicals, edaravone has anti-apoptotic, anti-necrotic and anti-cytokine effects in various diseases. Here, we critically review the literature on its clinical efficacy and examine whether edaravone should be considered a candidate for worldwide development, focusing on its effects on diseases other than cerebral infarction. Edaravone has been safely used as a free radical scavenger for more than 10 years; we propose that edaravone may offer a novel treatment option for several diseases.

Matrine attenuates endotoxin-induced acute liver injury after hepatic ischemia/reperfusion in rats

PURPOSE

Hepatic ischemia/reperfusion (HIR) injury is an unavoidable consequence of major liver surgery, during which endotoxemia often takes place. This study aimed to investigate whether matrine has a protective effect against HIR-induced liver injury aggravated by endotoxin.

METHODS

Wistar rats were subjected to 30 min of HIR followed by lipopolysaccharide (LPS) (0.5 mg/kg) administration. At the indicated time points, six rats from each group (24 rats) were randomly euthanized to collect blood samples and livers.

RESULTS

Preadministration of matrine protected livers from injury induced by HIR+LPS as the histological score, myeloperoxidase activity and malondialdehyde contents, expression of macrophage-inflammatory protein-2, DNA-binding activity of nuclear factor κB, and serum levels of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, alkaline phosphatase, tumor necrosis factor-α, soluble intercellular adhesion molecule-1, and nitric oxide were significantly reduced, and serum levels of interleukin-6 were further increased. HIR+LPS markedly induced cell apoptosis and necrosis, and upregulated the expression of cleaved caspase-3, Fas, and FasL. Matrine significantly reduced cell necrosis, but had a nonsignificant inhibitory effect on cell apoptosis and expression of cleaved caspase-3 and FasL.

CONCLUSIONS

Matrine attenuates endotoxin-induced acute liver injury after HIR mainly by its anti-inflammatory and antioxidative activities, and has little inhibitory effect on cell apoptosis.

Peroxidation of n-3 Polyunsaturated Fatty Acids Inhibits the Induction of iNOS Gene Expression in Proinflammatory Cytokine-Stimulated Hepatocytes

Eicosapentaenoic acid and docosahexaenoic acid (EPA/DHA), n-3 polyunsaturated fatty acids (PUFAs), have a variety of biological activities including anti-inflammatory and anticancer effects. We hypothesized that their peroxidized products contributed in part to anti-inflammatory effects. In the liver, the production of nitric oxide (NO) by inducible nitric oxide synthase (iNOS) has been implicated as one of the factors in hepatic inflammation and injury. We examined whether the peroxidation of EPA/DHA influences the induction of iNOS and NO production in proinflammatory cytokine-stimulated cultured hepatocytes, which is in vitro liver inflammation model. Peroxidized EPA/DHA inhibited the induction of iNOS and NO production in parallel with the increased levels of their peroxidation, whereas unoxidized EPA/DHA had no effects at all. Peroxidized EPA/DHA reduced the activation of transcription factor, NF-κB, and the expression of the iNOS antisense transcript, which are involved in iNOS promoter transactivation (mRNA synthesis) and its mRNA stabilization, respectively. These findings demonstrated that peroxidized products of EPA/DHA suppressed the induction of iNOS gene expression through both of the transcriptional and posttranscriptional steps, leading to the prevention of hepatic inflammation.

Sivelestat suppresses iNOS gene expression in proinflammatory cytokine-stimulated hepatocytes

BACKGROUND

Recent evidence has indicated that sivelestat, a neutrophil elastase inhibitor, has liver-protective effects in a variety of liver injuries. Proinflammatory cytokines including interleukin (IL)-1β stimulate the induction of inducible nitric oxide synthase (iNOS) gene expression, leading to excess production of NO and resulting in liver damage. We hypothesized that inhibition of iNOS induction underlies the protective effects of sivelestat on the liver. The objective of this study was to investigate whether sivelestat directly influences iNOS induction in cultured hepatocytes, which is used as a simple in vitro injury model, and to determine the mechanism involved.

METHODS

Primary cultured rat hepatocytes were treated with IL-1β in the presence or absence of sivelestat. The induction of iNOS and its signaling pathway were analyzed.

RESULTS

Sivelestat inhibited the induction of iNOS mRNA and its protein, followed by decreased production of NO. Transfection and iNOS gene antisense-transcript experiments revealed that sivelestat reduced the levels of iNOS mRNA at both the promoter activation and mRNA stabilization steps. However, sivelestat had no effects on the degradation of IκB and nuclear translocation of NF-κB subunit p65, although it moderately blocked the activation of NF-κB. In contrast, sivelestat blocked the upregulation of IL-1 receptor I through the inactivation of phosphatidylinositol 3-kinase/Akt.

CONCLUSIONS

Delayed sivelestat addition experiments demonstrated that the destabilization of the iNOS mRNA contributed more significantly to the inhibitory effects of sivelestat than the reduction in iNOS mRNA synthesis. Sivelestat may provide useful therapeutic effects through the suppression of iNOS induction involved in liver injury.

Protective effects of taurine against endotoxin-induced acute liver injury after hepatic ischemia reperfusion

Hepatic ischemia reperfusion (HIR) not only results in liver injury, but also leads to endotoxemia, which aggravates HIR-induced liver injury and dysfunction, or even causes liver failure. Taurine has been shown to protect organs from ischemia reperfusion or endotoxin by its anti-oxidant and anti-inflammatory activities. The aim of this study was to investigate whether taurine could attenuate endotoxin-induced acute liver injury after HIR. Wistar rats subjected to 30 min of hepatic ischemia followed by reperfusion and lipopolysaccharide (LPS) (0.5 mg/kg) administration, exhibited liver dysfunction (elevated serum levels of ALT, AST and LDH) and hepatic histopathological alteration. The serum levels of TNF-alpha and production of myeloperoxidase (MPO) and malondialdehyde (MDA) in liver tissues and apoptosis of hepatocytes were also increased after the combination of HIR and LPS. However, pre-administration of taurine protected livers from injury induced by the combination of HIR + LPS as the histological score, apoptotic index, MPO activity and production of MDA in liver tissues, and serum levels of AST, ALT, LDH and TNF-alpha, were significantly reduced. The expression of caspase-3, Fas and Fas ligand was upregulated in homogenates of livers from rats subjected to HIR and LPS, and this elevated expression could be inhibited by taurine. In summary, the results further emphasize the potential utilization of taurine in protecting livers against endotoxin-induced injury especially after HIR, by its anti-inflammatory, anti-oxidative and anti-apoptotic activities.

Electron spin resonance and spin trapping technique provide direct evidence that edaravone prevents acute ischemia–reperfusion injury of the liver by limiting free radical-mediated tissue damage

A novel free radical scavenger, 3-methyl-1-phenyl-2-pyrazolin-5-one (edaravone), is used for the treatment of acute ischemic stroke and is protective in several animal models of organ injury. We tested whether edaravone is protective against acute liver warm ischemia/reperfusion injury in the rat by acting as a radical scavenger. When edaravone was administered prior to ischemia and at the time of initiation of the reperfusion, liver injury was markedly reduced. Production of oxidants in the liver in this model was assessed in vivo by spin-trapping/electron spin resonance (ESR) spectroscopy. Ischemia/reperfusion caused an increase in free radical adducts rapidly, an effect markedly blocked by edaravone. Furthermore, edaravone treatment blunted ischemia/reperfusion-induced elevation in pro-inflammatory cytokines, infiltration of leukocytes and lipid peroxidation in the liver. These results demonstrate that edaravone is an effective blocker of free radicals in vivo in the liver after ischemia/reperfusion, leading to prevention of organ injury by limiting the deleterious effects of free radicals.

Suppressive effects of hydroxytyrosol on oxidative stress and nuclear Factor-kappaB activation in THP-1 cells

This study was designed to investigate whether hydroxytyrosol (HT) may ameliorate oxidative stress and nuclear factor kappaB (NF-kappaB) activation in the lipopolysaccharide (LPS)-stimulated THP-1 cell line. We measured the intracellular reactive oxygen species (ROS) formation using 2,7-dichlorofluorescein diacetate (DCFH-DA) as a fluorescent probe. Intracellular glutathione (GSH) level was estimated by fluorometric methods. Nitric oxide (NO) production was measured as nitrite (a stable metabolite of NO) concentrations using the Griess reagent system following Jiancheng Institute of Biotechnology protocols. To study the effect of HT on LPS-induced NF-kappaB activation in THP-1 cells, Western blot analysis of the nuclear fraction of cell lysates was performed. The results showed that treatment of THP-1 cells with HT significantly reduced LPS-stimulated NO production and ROS formation in a concentration-dependent manner. HT at 50 and 100 microM concentrations increased the GSH level. The specific DNA-binding activities of NF-kappaB on nuclear extracts from 50 and 100 microM HT treatments were significantly suppressed. The antioxidant N-acetylcysteine (NAC) also showed the same effects as HT on LPS-induced ROS and NO generation, change of GSH level, and NF-kappaB activation. These findings suggest that HT has antioxidant activity to suppress intracellular oxidative stress and NF-kappaB activation in THP-1 cells.

Edaravone prevents Fas-induced fulminant hepatic failure in mice by regulating mitochondrial Bcl-xL and Bax

Fulminant hepatic failure is a serious disease that has a poor cure rate unless liver transplantation is performed. Edaravone, a free radical scavenger, has been approved for the treatment of acute cerebral infarction, and its mechanism of action involves scavenging free radicals generated in ischemic tissues. We assessed the ability of 3-methyl-1-phenyl-2-pyrazolim-5-one (edaravone) to prevent Fas-induced acute liver failure in mice and examined the mechanisms underlying the observed effects. BALB/c mice were administered 0.25 microg/g (i.v.) body weight of a purified hamster agonist anti-Fas monoclonal antibody (clone Jo2). The mice also received either edaravone or isotonic sodium chloride solution before or after Jo2 treatment. Edaravone improved the survival rate of the mice markedly. Histopathological findings and serum aspartate aminotransferase levels showed that edaravone reduced the degree of liver injury caused by Jo2. Terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end labeling staining showed that edaravone reduced the number of apoptotic hepatocytes. Edaravone also prevented cytochrome c release and caspase 3 activity, recognized as markers of apoptosis after mitochondrial disruption. Therefore, we considered that the antiapoptotic activity of edaravone involved blocking signals in the mitochondria-dependent pathway of Fas-induced apoptosis. Mitochondrial Bcl-xL and Bax, which form a channel in the mitochondrial membrane and, by their balance, regulate its permeability, are involved in mitochondrial disruption. Western blotting showed that the Bcl-xL-Bax ratio of the edaravone group was much higher than that of the control group. In conclusion, edaravone might protect hepatocytes from Fas-induced mitochondria-dependent apoptosis by regulating mitochondrial Bcl-xL and Bax.