Oxidative Stress and Inflammation in Hepatic Diseases: Therapeutic Possibilities of N-Acetylcysteine

Counteraction of HCV-Induced Oxidative Stress Concurs to Establish Chronic Infection in Liver Cell Cultures

Hepatitis C virus (HCV) is a blood-borne pathogen causing acute and chronic hepatitis. A significant number of people chronically infected with HCV develop cirrhosis and/or liver cancer. The pathophysiologic mechanisms of hepatocyte damage associated with chronic HCV infection are not fully understood yet, mainly due to the lack of an in vitro system able to recapitulate the stages of infection in vivo. Several studies underline that HCV virus replication depends on redox-sensitive cellular pathways; in addition, it is known that virus itself induces alterations of the cellular redox state. However, the exact interplay between HCV replication and oxidative stress has not been elucidated. In particular, the role of reduced glutathione (GSH) in HCV replication and infection is still not clear. We set up an in vitro system, based on low m.o.i. of Huh7.5 cell line with a HCV infectious clone (J6/JFH1), that reproduced the acute and persistent phases of HCV infection up to 76 days of culture. We demonstrated that the acute phase of HCV infection is characterized by the elevated levels of reactive oxygen species (ROS) associated in part with an increase of NADPH-oxidase transcripts and activity and a depletion of GSH accompanied by high rates of viral replication and apoptotic cell death. Conversely, the chronic phase is characterized by a reestablishment of reduced environment due to a decreased ROS production and increased GSH content in infected cells that might concur to the establishment of viral persistence. Treatment with the prooxidant auranofin of the persistently infected cultures induced the increase of viral RNA titer, suggesting that a prooxidant state could favor the reactivation of HCV viral replication that in turn caused cell damage and death. Our results suggest that targeting the redox-sensitive host-cells pathways essential for viral replication and/or persistence may represent a promising option for contrasting HCV infection.

Age- and sex-dependent variation in the activity of antioxidant enzymes in the brown trout (Salmo trutta)

Oxidative stress is defined as the imbalance between pro-oxidant and antioxidant molecules in favor of the former and it represents one of the main driving forces of aging. To counteract the harmful effects of oxidative stress, organisms evolved a complex antioxidant system. According to the free radical theory of aging, while the production of reactive oxygen species (ROS) increases with age, the antioxidant defenses decline. Although this relationship has been investigated in diverse vertebrate taxa, the information in fish is scant and inconsistent, particularly for wild populations. Thus, the aim of the present study was the investigation of age- and sex-related changes of the antioxidant enzymes activity in free-living individuals of the brown trout (Salmo trutta). We measured the activity of the main enzymes involved in antioxidant protection, namely superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione S-transferase (GST), as well as lipid peroxidation, in the gills and the liver dissected from brown trout (1+- to 5+-year-old). A significant age-dependent variation in the activity of antioxidant enzymes was noted, with the exception of CAT. GPx activity followed a significant increasing trend with age in both the organs, while SOD decreased in the liver. Increased GST activity was found in the gills only. Lipid peroxidation levels significantly decreased with age in both the organs. SOD and CAT showed sex-dependent differences in the liver of brown trout, with males showing lower enzymatic activity than females. Our data contribute to improve the knowledge on the relationship between antioxidant enzyme activity, aging, and sex in fish.

Activation of Sirtuin 3 and Maintenance of Mitochondrial Integrity by N-Acetylcysteine Protects Against Bisphenol A-Induced Kidney and Liver Toxicity in Rats

Mitochondrial impairment ensuing from oxidative imbalance is related to adverse consequences of bisphenol A (BPA), a globally utilized industrial chemical. Recent evidence reveals sirtuin 3 (SIRT3) as a key regulator of mitochondrial homeostasis; however, its role in BPA toxicity remains unidentified. This study explored the potential benefits of N-acetylcysteine (NAC), an effective antioxidant, against BPA toxicity in the kidney and liver, and examined whether SIRT3 was involved in this condition. Male Wistar rats were fed with vehicle, BPA (5, 50 mg/kg), BPA (50 mg/kg) plus NAC (100 mg/kg) and were evaluated after 5 weeks. NAC treatment significantly diminished BPA-induced kidney and liver functional disorders, histopathological alterations, oxidative stress, and apoptosis. The increased mitochondrial reactive oxygen species, the disrupted membrane potential, the swelling, and the impaired mitochondrial fission caused by BPA were also mitigated upon concurrent treatment with NAC. The benefits of NAC were associated with enhanced AMPK-PGC-1α-SIRT3 signaling protein expressions, which led to decreased acetylation of superoxide dismutase 2 (SOD2) and increased expression of mitochondrial antioxidant manganese superoxide dismutase (MnSOD). The findings demonstrate the efficacy of NAC in protecting BPA-induced kidney and liver injury, which, in part, is mediated by activating SIRT3 and improving mitochondrial function, dynamics, and oxidative imbalance.

A hepatocyte-targeting near-infrared ratiometric fluorescent probe for monitoring peroxynitrite during drug-induced hepatotoxicity and its remediation

A novel hepatocyte-targeting near-infrared ratiometric fluorescent probe named Gal-NIR is developed for detecting ONOO⁻. The probe can target the hepatocyte and assess drug-induced liver injury and its remediation in living cells and mice.

Ambroxol attenuates cisplatin-induced hepatotoxicity and nephrotoxicity via inhibition of p-JNK/p-ERK

Hepatotoxicity and nephrotoxicity are important drawbacks of cisplatin. The objective of this study is to evaluate the ability of ambroxol in 2 different doses (35 and 70 mg/kg, i.p.) to protect liver and kidney from damage induced by a single dose of cisplatin (10 mg/kg, i.p.) in comparison with N-acetylcysteine (250 mg/kg, i.p.). Inflammatory, oxidative stress, and apoptotic biomarkers were investigated to show the influence of ambroxol on hepatotoxicity and nephrotoxicity. Ambroxol decreased the elevated activity of liver enzymes (aspartate aminotransferase and alanine aminotransferase) and kidney function tests (blood urea nitrogen and creatinine). Ambroxol mitigated cisplatin inflammatory damage by inhibition of tumor necrosis factor-α, interleukin-1β, and nuclear factor kappa-B and elevation of nuclear factor erythroid 2-related factor 2. Moreover, ambroxol inhibited oxidative damage indicated by reduction of malondialdehyde and replenished the store of reduced glutathione likely by upregulating glutathione reductase and superoxide dismutase. Elevation of phosphorylated c-Jun N-terminal kinases (p-JNK) and phosphorylated extracellular signal-regulated kinase (p-ERK) were attenuated by ambroxol associated with a decrease in the expression of caspase-3; these results were consistent with histopathological results. These results recommend ambroxol to be co-administered with cisplatin in cancer patients to ameliorate liver and kidney damage, and this was confirmed by MTT assay.

An intronic single nucleotide polymorphism in the MUTYH gene is associated with increased risk for HCV-induced hepatocellular carcinoma

BACKGROUND & AIMS

The role of base excision repair genes in human hepatocarcinogenesis has not yet been explored. Here, we investigated relationships between variants of these genes and the risk of developing hepatocellular carcinoma (HCC).

METHODS

Nineteen tagging SNPs in base excision repair genes (including MUTYH, OGG1 and MTH1) were genotyped using iPLEX assays; one significant SNP was found and confirmed in Japanese patients with chronic hepatitis C (CHC) (n = 38 HCC and 55 controls). The effects of modifying the intronic variants were determined by luciferase assays. MUTYH-null mice were used to examine the involvement of oxidative stress and DNA repair enzymes in hepatocarcinogenesis.

RESULTS

Significant associations were found for a single intron SNP (rs3219487) in the MUTYH gene. The risk of developing HCC in patients with A/A or G/A genotypes was higher than in those with the G/G genotype (OR = 9.27, 95% CI = 2.39 -32.1, P = 0.0005). MUTYH mRNA levels in both peripheral mononuclear cells were significantly lower in G/A or A/A genotyped subjects (P = 0.0157 and 0.0108, respectively). We found that -2000 in the MUTYH promoter region is involved in enhanced expression of MUTYH by insertion of a major allele sequence of rs3219487. Liver tumors were observed in MUTYH-null mice after 12 months´ high iron diet, but no tumors developed when dietary anti-oxidant (N-Acetyl-L-cysteine) was also provided.

CONCLUSIONS

CHC patients with the rs3219487 adenine allele had a significantly increased risk of developing HCC. MUTYH-null mice with iron-associated oxidative stress were susceptible to development of liver tumors unless prevented by dietary anti-oxidants.

Computational Modeling of Oxidative Stress in Fatty Livers Elucidates the Underlying Mechanism of the Increased Susceptibility to Ischemia/Reperfusion Injury

QUESTION

Donor liver organs with moderate to high fat content (i.e. steatosis) suffer from an enhanced susceptibility to ischemia/reperfusion injury (IRI) during liver transplantation. Responsible for the cellular injury is an increased level of oxidative stress, however the underlying mechanistic network is still not fully understood.

METHOD

We developed a phenomenological mathematical model of key processes of hepatic lipid metabolism linked to pathways of oxidative stress. The model allows the simulation of hypoxia (i.e. ischemia-like conditions) and reoxygenation (i.e. reperfusion-like conditions) for various degrees of steatosis and predicts the level of hepatic lipid peroxidation (LPO) as a marker of cell damage caused by oxidative stress.

RESULTS & CONCLUSIONS

Our modeling results show that the underlying feedback loop between the formation of reactive oxygen species (ROS) and LPO leads to bistable systems behavior. Here, the first stable state corresponds to a low basal level of ROS production. The system is directed to this state for healthy, non-steatotic livers. The second stable state corresponds to a high level of oxidative stress with an enhanced formation of ROS and LPO. This state is reached, if steatotic livers with a high fat content undergo a hypoxic phase. Theoretically, our proposed mechanistic network would support the prediction of the maximal tolerable ischemia time for steatotic livers: Exceeding this limit during the transplantation process would lead to severe IRI and a considerable increased risk for liver failure.

Protein kinase Cδ knockout mice are protected from cocaine-induced hepatotoxicity

We investigated whether protein kinase Cδ (PKCδ) mediates cocaine-induced hepatotoxicity in mice. Cocaine treatment (60 mg/kg, i.p.) significantly increased cleaved PKCδ expression in the liver of wild-type (WT) mice, and led to significant increases in oxidative parameters (i.e., reactive oxygen species, 4-hydroxylnonenal and protein carbonyl). These cocaine-induced oxidative burdens were attenuated by pharmacological (i.e., rottlerin) or genetic depletion of PKCδ. We also demonstrated that treatment with cocaine resulted in significant increases in nuclear factor erythroid-2-related factor 2 (Nrf-2) nuclear translocation and increased Nrf-2 DNA-binding activity in wild-type (WT) mice. These increases were more pronounced in the rottlerin-treated WT or PKCδ knockout mice than in the saline-treated WT mice. Although cocaine treatment increased Nrf-2 nuclear translocation, DNA binding activity, and γ-glutamyl cysteine ligases (i.e., GCLc and GCLm) mRNA expressions, while it reduced the glutathione level and GSH/GSSG ratio. These decreases were attenuated by PKCδ depletion. Cocaine treatment significantly increased alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in the serum of WT mice signifying the hepatic damage. These increases were also attenuated by PKCδ depletion. In addition, cocaine-induced hepatic degeneration in WT mice was evident 1 d post-cocaine. At that time, cocaine treatment decreased Bcl-2 and Bcl-xL levels, and increased Bax, cytosolic cytochrome c, and cleaved caspase-3 levels. Pharmacological or genetic depletion of PKCδ significantly ameliorated the pro-apoptotic properties and hepatic degeneration. Therefore, our results suggest that inhibition of PKCδ, as well as activation of Nrf-2, is important for protecting against hepatotoxicity induced by cocaine.

Effects of Antioxidants in Reducing Accumulation of Fat in Hepatocyte

The progress of the hepatic steatosis (HS), a clinicopathological status, is influenced by cellular oxidative stress, lipogenesis, fatty acid (FA) oxidation, and inflammatory responses. Because antioxidants are gaining attention as potent preventive agents for HS, we aimed to investigate anti-lipogenic effects of the antioxidants vitamin C (VC), N-acetylcysteine (NAC), and astaxanthin (ATX) using hepatocytes. For this, we established an in vitro model using 1 mM oleic acid (OA) and human liver hepatocellular carcinoma (HepG2) cells; 10 μM antioxidants were evaluated for their ability to reduce fat accumulation in hepatocytes. Our results showed that all three antioxidants were effective to reduce fat accumulation for the molecular targets such as reduction in lipid droplets, triglyceride (TG) concentration, reactive oxygen species (ROS) production, and cell apoptosis, as well as in gene expressions of endoplasmic reticulum (ER) stress-related effectors, lipogenesis, and inflammatory cytokines. There were simultaneous increases in diphenyl-1-picrylhydrazyl (DPPH) radical scavenging effect, cell survival, AMPK phosphorylation, NRF2-related gene expression for cellular defense, and FA β-oxidation. However, among these, ATX more effectively inhibited ER stress and lipogenesis at the intracellular level than VC or NAC. Consequently, ATX was also more effective in inhibiting cell death, lipotoxicity, and inflammation. Our result emphasizes that ATX achieved greater lipotoxicity reduction than VC and NAC.

A new bioluminescent imaging technology for studying oxidative stress in the testis and its impacts on fertility

PURPOSE

Excessive oxidative stress (OS) leads to cellular dysfunctions and cell death and constitutes a major cause of male infertility. However, the etiologies of increased reactive oxygen species (ROS) in male infertility is not fully understood. One major limitation is the lack of an in vivo imaging system that can be used to effectively study the impact of excessive ROS in the testis. Recently, we discovered that the hepatocellular carcinoma reporter (HCR) mice previously generated in our laboratory also expressed luciferase in the spermatids of the testis. The goal of the current study is to use the HCR mice to detect OS in the testis and to investigate the potential use of this new system in studying OS-induced male infertility.

EXPERIMENTAL DESIGN

Bioluminescence imaging (BLI) was performed in HCR mice that were treated with peroxy caged luciferin-1 (PCL-1), an OS reporter, to establish a new mouse model for in vivo monitoring of the OS status inside the male reproductive tract. Subsequently, the effect of acetaminophen (APAP) overdose on the OS inside the testis and male fertility were determined. Lastly, APAP was co-administered with glutathione, an antioxidant reagent, to test if the HCR mice can serve as a model for the effective and rapid assessment of the potency of individual agents in modifying the OS inside the mouse testis.

RESULTS

The OS level in the testis in the HCR mice was readily detected by BLI. The use of this new model led to the discovery that APAP caused a sudden rise of OS in the testis and was a potent toxicant for the male reproductive system. Moreover, administration of glutathione was effective in preventing the APAP-induced elevation of OS and in ameliorating all of the OS-induced anomalies in the testis.

CONCLUSIONS

The HCR mice represent an excellent model for monitoring OS change in the mouse testis by real time BLI. APAP is a potent male reproductive toxicant and APAP-treated mice represent a valid model for OS-induced male infertility. This model can be used to study OS-induced damage in male reproductive tract and in assessing the effects of therapeutic agents on the relative levels of OS and male fertility.

Superoxide Anion Production and Bioenergetic Profile in Young and Elderly Human Primary Myoblasts

Sarcopenia is the age-related loss of skeletal muscle mass, strength, and function. It is associated with regenerative difficulties by satellite cells, adult muscle stem cells, and alteration of oxidative management, mainly the increase in superoxide anions (O₂^•-). We aimed to investigate the relation between regenerative deficit in elderly and increase in O₂^•- production along with mitochondrial alterations. Myoblasts and myotubes from skeletal muscle of young and elderly healthy subjects (27.8 ± 6 and 72.4 ± 6.5 years old) were measured: (1) superoxide dismutase activity and protein content, (2) mitochondrial O₂^•- production levels, (3) O₂^•- production variability, and (4) mitochondrial bioenergetic profile. Compared to young myoblasts, elderly myoblasts displayed decreased SOD2 protein expression, elevated mitochondrial O₂^•- baseline levels, and decreased oxidative phosphorylation and glycolysis. Additionally, elderly versus young myotubes showed elevated mitochondrial O₂^•- levels when stressed with N-acetyl cysteine or high glucose and higher glycolysis despite showing comparable oxidative phosphorylation levels. Altogether, the elderly may have less metabolic plasticity due to the impaired mitochondrial function caused by O₂^•-. However, the increased energy demand related to the differentiation process appears to activate compensatory mechanisms for the partial mitochondrial dysfunction.

Possible Synergistic Effects of Glutathione and C-Reactive Protein in the Progression of Liver Cirrhosis

Liver cirrhosis is often associated with increased inflammatory responses and changes of glutathione (GSH) status. The possible interactions between these two factors in mediating damages of liver function remain unclear. Here, we measured the inflammatory responses and GSH status in liver cirrhotic patients and compared them with healthy subjects. In addition, we assessed the relationship of the GSH status and levels of inflammatory markers with the severity of the disease. This was a cross-sectional study. In total, we recruited 63 liver cirrhotic patients with Child⁻Turcotte⁻Pugh class A scores, and 12 patients with class B⁻C scores, together with 110 healthy subjects. Patients with class B⁻C scores showed the highest level of high-sensitivity C-reactive protein (hs-CRP) when compared with class A patients or healthy subjects. Patients in class A group had significantly higher GSH levels when compared with class B⁻C group or healthy subjects. After adjusting for potential confounders and each other, serum hs-CRP levels showed positive association with the Child⁻Turcotte⁻Pugh scores, while GSH levels showed negative association with Child⁻Turcotte⁻Pugh scores. Interactions were found between levels of plasma GSH and serum hs-CRP (β = 0.004, p = 0.016). CRP and GSH levels, which had showed interactions, were associated with the severity of liver cirrhosis.

N-Acetyl-l-Cysteine treatment efficiently prevented pre-diabetes and inflamed-dysmetabolic liver development in hypothalamic obese rats

AIM

Hypothalamic obese rats are characterized by pre-diabetes, dyslipidemia, hyperadiposity, inflammation and, liver dysmetabolism with oxidative stress (OS), among others. We studied endocrine-metabolic dysfunctions and, liver OS and inflammation in both monosodium l-glutamate (MSG)-neonatally damaged and control litter-mate (C) adult male rats, either chronically treated with N-Acetyl-l-Cysteine since weaned (C-NAC and MSG-NAC) or not.

METHODOLOGY

We evaluated circulating TBARS, glucose, insulin, triglycerides, uric acid (UA) and, aspartate and alanine amino-transferase; insulin sensitivity markers (HOMA indexes, Liver Index of Insulin Sensitivity -LISI-) were calculated and liver steps of the insulin-signaling pathway were investigated. Additionally, we monitored liver OS (protein carbonyl groups, GSH and iNOS level) and inflammation-related markers (COX-2 and TNFα protein content; gene expression level of Il1b, Tnfα and Pai-1); and carbohydrate and lipid metabolic functions (glucokinase/fructokinase activities and, mRNA levels of Srebp1c, Fas and Gpat).

KEY FINDINGS

Chronic NAC treatment in MSG rats efficiently decreased the high circulating levels of triglycerides, UA, transaminases and TBARS, as well as peripheral (high insulinemia and HOMA indexes) and liver (LISI and the P-AKT:AKT and P-eNOS:eNOS protein ratio values) insulin-resistance. Moreover, NAC therapy in MSG rats prevented liver dysmetabolism by decreasing local levels of OS and inflammation markers. Finally, NAC-treated MSG rats retained normal liver glucokinase and fructokinase activities, and Srebp1c, Fas and Gpat (lipogenic genes) expression levels.

SIGNIFICANCE

Our study strongly supports that chronic oral antioxidant therapy (NAC administration) prevented the development of pre-diabetes, dyslipidemia, and inflamed-dysmetabolic liver in hypothalamic obese rats by efficiently decreasing high endogenous OS.

Acrylamide-induced oxidative stress and inflammatory response are alleviated by N-acetylcysteine in PC12 cells: Involvement of the crosstalk between Nrf2 and NF-κB pathways regulated by MAPKs

Acrylamide (ACR) is a classic neurotoxin in animals and humans. However, the mechanism underlying ACR neurotoxicity remains controversial, and effective prevention and treatment measures against this condition are scarce. This study focused on clarifying the crosstalk between the involved signaling pathways in ACR-induced oxidative stress and inflammatory response and investigating the protective effect of antioxidant N-acetylcysteine (NAC) against ACR in PC12 cells. Results revealed that ACR exposure led to oxidative stress characterized by significant increase in reactive oxygen species (ROS) and malondialdehyde (MDA) levels and glutathione (GSH) consumption. Inflammatory response was observed based on the dose-dependently increased levels of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6). NAC attenuated ACR-induced enhancement of MDA and ROS levels and TNF-α generation. In addition, ACR activated nuclear transcription factor E2-related factor 2 (Nrf2) and nuclear factor-κB (NF-κB) signaling pathways. Knockdown of Nrf2 by siRNA significantly blocked the increased NF-κB p65 protein expression in ACR-treated PC12 cells. Down-regulation of NF-κB by specific inhibitor BAY11-7082 similarly reduced ACR-induced increase in Nrf2 protein expression. NAC treatment increased Nrf2 expression and suppressed NF-κB p65 expression to ameliorate oxidative stress and inflammatory response caused by ACR. Further results showed that mitogen-activated protein kinases (MAPKs) pathway was activated prior to the activation of Nrf2 and NF-κB pathways. Inhibition of MAPKs blocked Nrf2 and NF-κB pathways. Collectively, ACR activated Nrf2 and NF-κB pathways which were regulated by MAPKs. A crosstalk between Nrf2 and NF-κB pathways existed in ACR-induced cell damage. NAC protected against oxidative damage and inflammatory response induced by ACR by activating Nrf2 and inhibiting NF-κB pathways in PC12 cells.

Activated carbon N-acetylcysteine microcapsule protects against nonalcoholic fatty liver disease in young rats via activating telomerase and inhibiting apoptosis

Non-alcoholic fatty liver disease (NAFLD) is becoming one of the world's most common chronic liver diseases in childhood, yet no therapy is available that has been approved by the food and drug administration (FDA). Previous studies have reported that telomere and telomerase are involved the development and progression of NAFLD. This study was designed to investigate the potential beneficial effects of activated carbon N-acetylcysteine (ACNAC) microcapsules on the development of NAFLD in young rats as well as the underlying mechanism(s) involved. Three-week old male Sprague Dawley rats were given high-fat diet (HFD) with/without ACNAC treatment for 7 consecutive weeks. Liver pathologies were determined by hematoxylin and eosin (H&E) and Oil Red O staining, as well as by changes in biochemical parameters of plasma alanine transaminase (ALT) and aspartate transaminase (AST) levels, respectively. Glucose homeostasis was evaluated by the glucose tolerance test and the liver telomere length and activity were measured by real time PCR and telomeric repeat amplification protocol (TRAP). Western blot analysis was performed to determine the expression level of Bcl-2, Bax and Caspase-3. Our results demonstrated that ACNAC supplementation improved liver pathologies of rats that received long-term HFD feeding. ACNAC supplementation prevented HFD-induced telomere shortening and improved telomerase activity. Moreover, in comparison to HFD-fed rats, ACNAC supplementation markedly increased the expression of Bcl-2, but significantly decreased the expression of Bax and Caspase-3 in juvenile rats. Together, these results indicate that ACNAC may be a promising choice for preventing and treating NAFLD among children.

Role of mitochondria and mitochondria-targeted agents in non-alcoholic fatty liver disease

Mitochondria play a pivotal role in the fatty acid oxidation and have been found to be affected early during the macrovesicular fat accumulation in the hepatocytes. The fatty infiltration is the primary cause of oxidative stress and inflammation in the non-alcoholic fatty liver disease (NAFLD), which can lead to the peroxidation of phospholipids, such as cardiolipin. Oxidative stress-induced damage to mitochondrial DNA can result in the impairment of oxidative phosphorylation and further increases the generation of reactive oxygen species. The mitochondrial damage may eventually lead to apoptotic death of hepatocytes. The apoptosis along with the generated cytokines from the stellate and Kupffer cells further augment the fibrotic changes to advance the disease. Hence, alleviation of the mitochondrial impairment, particularly in the early stages of NAFLD, may prevent the progression of the disease. Among the various experimentally studied mitochondrial-targeted agents, triphenylphosphonium cation ligated ubiquinone Q10 and vitamin E, Szeto-Scheller peptides, and superoxide dismutase mimetic-salen manganese complexes (EUK-8 and EUK-134) have been found to be most promising. In addition to these mitochondrial-targeted agents, a novel area of therapy called mitotherapy have also emerged. However, clinical studies conducted so far are still fragmentary to validate their efficacy. This review article discusses the mitochondria-targeted molecules and their potential role in the treatment of NAFLD.

The hepatoprotective role of reduced glutathione and its underlying mechanism in oxaliplatin-induced acute liver injury

Currently, the underlying mechanism of oxaliplatin (OXA) induced live injury is unclear. In addition, there is no standard clinical treatment for OXA-induced acute liver injury (ALI). In this study, we established an animal model of OXA-induced ALI, and studied the role of oxidative stress in OXA-induced ALI and the impacts of reduced glutathione (GSH) treatment on OXA-induced ALI. To establish an OXA-induced ALI model, KM mice received intraperitoneal injection of OXA (8 mg/kg) for 4 days. Serum alanine aminotransferase (ALT), aspartate aminotransferase levels (AST), hepatic pathology and oxidative stress indicators in liver tissues were analyzed. To study the impact of GSH treatment on OXA-induced ALI, mice were treated with GSH (400 mg/kg, i.p). In this ALI mouse model, ALT and AST levels were significantly increased (P<0.01). Liver pathological examination revealed varying degrees of liver cell turbidity and degeneration, even balloon-like changes and focal necrosis, and sinusoidal hemorrhage in some cells. Compared with control group, the malondialdehyde (MDA) and GSH levels were significantly increased in OXA-treated group (P<0.01), while the superoxide dismutase SOD and GSH-peroxidase levels were decreased after OXA withdrawal (P<0.01). When GSH was used to treat OXA-induced ALI mice, the pathological injury of liver tissues was alleviated, and serum ALT and AST were significantly decreased. In addition, GSH treatment could reduce the OXA-induced increase of MDA level (P<0.05) in liver tissues, but had no impact on SOD level (P>0.05). We have successfully established an OXA-induced ALI model. Using this model, we discover that oxidative stress plays an important role in OXA-induced ALI. GSH-based hepatoprotective therapy can partially inhibit oxidative stress and alleviate OXA-induced ALI.

Sex-dependent effects of subacute mercuric chloride exposure on histology, antioxidant status and immune-related gene expression in the liver of adult zebrafish (Danio rerio)

Mercury (Hg) is a global pollutant that causes negative health effects. In order to assess Hg-induced hepatotoxicity in fish and examine whether gender differences existed in response to Hg exposure, adult zebrafish were exposed to 0, 15 and 30 μg L^-1 Hg²⁺ for 30 days, and histology, antioxidant status and the transcription levels of several immune-related genes were examined in the liver. Hg²⁺ exposure caused a dose-dependent increase in histopathological lesions of the liver, including vacuolization, parenchyma disorganization and pyknotic nucleus, and these lesions were more severe in males than in females. In females, Hg²⁺ exposure decreased CAT activity and its mRNA levels, while increased GSH content and the expressions of sod1, gpx1a, gstr and keap1. In males, the decrease in cat1 expression and the increase in GST activity, GSH and MDA contents as well as gpx1a, gstr, nrf2 and keap1 mRNA levels were observed in Hg²⁺-exposed groups, but the activities of CAT, SOD and GPX were only stimulated in the 15 μg L^-1 Hg²⁺ group. Moreover, both in females and males, Hg²⁺ exposure down-regulated il-8 expression while up-regulated il-10 and lyz mRNAs. However, the down-regulation of il-1β and tnfα was detected only in males under Hg²⁺ treatments. Thus, our results indicated that HgCl₂ exposure induced histopathological damage, oxidative stress and immunotoxicity in the liver of zebrafish. Different response patterns of histology, antioxidant status and immune defenses to Hg²⁺ between females and males suggested sex-dependent effects of Hg, and males showed more vulnerable to Hg²⁺ exposure than females.

Identification of novel N-acetylcysteine derivatives for the treatment of hepatocellular injury

New anti-hepatocellular injury drugs with better curative effects and fewer side effects are urgently needed at present. In this study, a series of novel N-acetylcysteine (NAC) derivatives were designed, synthesized and biologically evaluated for their anti-hepatocellular injury activities against two different cell models. In the biological evaluation against hydrogen peroxide (H2O2)-induced LO2 hepatocytes, half of the target compounds exhibited moderate to potent activities in improving the model cell viability, and two compounds (6a and 6b) displayed more potent activities in decreasing malondialdehyde (MDA) levels than the positive control NAC. In further 4-acetamidophenol (APAP)-induced LO2 cell experiment, compounds 6a and 6b could not only improve the cell viability but also significantly reduce the secretion of MDA. Additionally, compound 6a displayed excellent Caco-2 permeability and oral bioavailability in rats. All these experimental results suggested that compounds 6a and 6b could serve as potential lead molecules for further development of anti-hepatocellular injury drugs.

Kyungheechunggan-Tang-01, a New Herbal Medication, Suppresses LPS-Induced Inflammatory Responses through JAK/STAT Signaling Pathway in RAW 264.7 Macrophages

Medicinal plants have been used as alternative therapeutic tools to alleviate inflammatory diseases. The objective of this study was to evaluate anti-inflammatory properties of Kyungheechunggan-tang- (KCT-) 01, KCT-02, and Injinchunggan-tang (IJCGT) as newly developed decoctions containing 3–11 herbs in LPS-induced macrophages. KCT-01 showed the most potent inhibitory effects on LPS-induced NO, PGE₂, TNF-α, and IL-6 production among those three herbal formulas. In addition, KCT-01 significantly inhibited LPS-induced iNOS and COX-2 at protein levels and expression of iNOS, COX-2, TNF-α, and IL-6 at mRNA levels. Molecular data revealed that KCT-01 attenuated the activation of JAK/STAT signaling cascade without affecting NF-κB or AP-1 activation. In ear inflammation induced by croton oil, KCT-01 significantly reduced edema, MPO activity, expression levels of iNOS and COX-2, and STAT3 phosphorylation in ear tissues. Taken together, our findings suggest that KCT-01 can downregulate the expression of proinflammatory genes by inhibiting JAK/STAT signaling pathway under inflammatory conditions. This study provides useful data for further exploration and application of KCT-01 as a potential anti-inflammatory medicine.

Fibroblast growth factor 2 (FGF2) regulates cytoglobin expression and activation of human hepatic stellate cells via JNK signaling

Cytoglobin (CYGB) belongs to the mammalian globin family and is exclusively expressed in hepatic stellate cells (HSCs) in the liver. In addition to its gas-binding ability, CYGB is relevant to hepatic inflammation, fibrosis, and cancer because of its anti-oxidative properties; however, the regulation of CYGB gene expression remains unknown. Here, we sought to identify factors that induce CYGB expression in HSCs and to clarify the molecular mechanism involved. We used the human HSC cell line HHSteC and primary human HSCs isolated from intact human liver tissues. In HHSteC cells, treatment with a culture supplement solution that included fibroblast growth factor 2 (FGF2) increased CYGB expression with concomitant and time-dependent α-smooth muscle actin (αSMA) down-regulation. We found that FGF2 is a key factor in inducing the alteration in both CYGB and αSMA expression in HHSteCs and primary HSCs and that FGF2 triggered the rapid phosphorylation of both c-Jun N-terminal kinase (JNK) and c-JUN. Both the JNK inhibitor PS600125 and transfection of c-JUN-targeting siRNA abrogated FGF2-mediated CYGB induction, and conversely, c-JUN overexpression induced CYGB and reduced αSMA expression. Chromatin immunoprecipitation analyses revealed that upon FGF2 stimulation, phospho-c-JUN bound to its consensus motif (5'-TGA(C/G)TCA), located -218 to -222 bases from the transcription initiation site in the CYGB promoter. Of note, in bile duct-ligated mice, FGF2 administration ameliorated liver fibrosis and significantly reduced HSC activation. In conclusion, FGF2 triggers CYGB gene expression and deactivation of myofibroblastic human HSCs, indicating that FGF2 has therapeutic potential for managing liver fibrosis.

Effects of Pomegranate (Punica Granatum L.) Seed and Peel Methanolic Extracts on Oxidative Stress and Lipid Profile Changes Induced by Methotrexate in Rats

Purpose: Methotrexate (MTX) is prescribed in many diseases and can result in oxidative stress (OS) followed by injuries in some tissues. Antioxidants administration are effective in reducing OS. Pomegranate exhibits high anti-oxidant capacities. This study investigated whether pomegranate seed and peel methanolic extracts (PSE and PPE) could protect against MTX-induced OS and lipid profile changes in rats.

Methods: Forty-eight rats were randomly divided into 6 groups: control group (normal salin), PSE group (500 mg/kg, orally), PPE group (500 mg/kg, orally), MTX group (10 mg/kg, IM), MTX and PSE group, and MTX and PPE group. Blood samples were taken for analysis in the end of the procedure.

Results: The findings showed a significant reduction in Glutathione peroxidase (GPx) and Superoxide dismutase (SOD), and an enhancement in malondialdehyde (MDA) values after MTX treatment (p < 0.05). SOD and GPx levels reached the levels of the control group in MTX+SPE and MTX+PPE groups. No significant differences were observed in catalase (CAT) and total antioxidant capacity (TAC) levels between groups. The results showed a significant decrease in total cholesterol (TC), low density lipoprotein (LDL), and high density lipoprotein (HDL) in the MTX treated group (p < 0.01). The values of TC, HDL, and LDL became elevated to the normal control levels in the MTX+PSE and MTX+PPE treated groups.

Conclusion: The results showed the OS induced by MTX and the protective effects of PSE and PPE against MTX-induced serum oxidative stress and lipid profile changes in rats.

The effect of N-acetylcysteine supplementation on serum homocysteine levels and hepatic and renal oxidative stress in homocysteine thiolactone-treated rats

The effect of N-acetylcysteine (NAC) (1 g/kg body weight/day) on serum homocysteine (Hcy) levels, insulin resistance (IR), and hepatic and renal prooxidant-antioxidant balance was evaluated in rats treated with homocysteine thiolactone (HcyT) (500 mg/kg body weight/day for 6 weeks). Reactive oxygen species (ROS), malondialdehyde (MDA), glutathione, ferric reducing antioxidant power, and superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were determined in the liver and kidney. HcyT elevated serum Hcy levels and caused IR, but liver and kidney function tests remained unchanged. HcyT increased ROS and MDA without any change in hepatic antioxidants, but it elevated renal SOD and GSH-Px activities. NAC decreased serum Hcy, hepatic and renal ROS and MDA levels, and renal SOD and GSH-Px activities in rats with high Hcy levels. However, it did not ameliorate IR. Our results indicate that NAC supplementation may be effective in decreasing Hcy levels and Hcy-induced hepatic and renal oxidative stress.

Intraperitoneal gardiquimod protects against hepatotoxicity through inhibition of oxidative stress and inflammation in mice with sepsis

Many reports recapitulate the contribution of reactive oxygen species (ROS) over-accumulation to the organ damage; it is of significance to strictly target ROS production. In this study, we evaluated the potential role of TLR7 agonist gardiquimod (GDQ) in oxidative stress (OS) in liver injury induced by sepsis. Here, we observed that intraperitoneal pretreatment with GDQ dramatically elevated the septic survival rate and effectively attenuated the septic liver injury. Interestingly, the increased ROS and inflammatory factor IL-6 levels were reversed after GDQ intervention. Subsequently, Western blot was employed to determine the definite mechanism. As expected, it was showed that the upregulation of c-Jun N-terminal kinase (JNK)/c-Jun pathway in liver of septic animals was considerably suppressed by GDQ pre-exposure. Our current result highlight that pre-administration of GDQ ameliorated sepsis induced hepatotoxicity and reduced the generation of IL-6 and OS responses, which was associated with downregulation of JNK/c-Jun pathway. Our strategies might be ultimately beneficial in mitigating liver injury symptom.

Effect of Sodium Arsenite on the Expression of Antioxidant Genes (SOD2 and CAT) in MCF-7 and Jurkat Cell Lines

BACKGROUND

Sodium arsenite (NaAsO2) has potent cytotoxic activity in human cancer cells. Oxidative stress has been suggested as a mechanism for arsenic-induced carcinogenesis. The purpose of the present study was to evaluate the alteration of mRNA levels of catalase (CAT) and superoxide dismutase 2 (SOD2) in MCF-7 and Jurkat cells after exposure to NaAsO₂.

METHODS

Methylthiazol tetrazolium (MTT) viability assay was performed to evaluate cytotoxicity of NaAsO₂ in MCF-7 and Jurkat cells. For evaluating the expression levels of the CAT and SOD2, we used two concentrations of NaAsO₂ (5 and 15 μM), lower than the concentrations at which 50% of cell viability were lost. The cells were treated with co-treatment of NaAsO₂ (15 μM) and N-acetyl-cysteine (NAC; 5 μM) in the media for 24 h. The control cells were maintained in sodium arsenite free growth medium. The experiments were done triplicate. Using quantitative real-time PCR, the expression levels of CAT and SOD2 were quantified. One sample student's t test was performed for comparisons of mRNA levels between treatment groups and their corresponding untreated control cells.

RESULTS

CAT mRNA level decreased significantly in both cell lines following exposure to NaAsO₂ (P<0.05). Expression levels of SOD2 decreased in Jurkat cells and increased in MCF-7 cells after treatment with NaAsO₂ (P<0.05).

CONCLUSION

After cells exposure to NaAsO₂, CAT mRNA level decreased in both examined cell lines but the alterations of SOD2 mRNA level is cell specific. The NAC modulated the NaAsO₂ associated alterations of CAT and SOD2 mRNA levels, therefore, the NaAsO₂ might act through inducing reactive oxygen species.

Insights into the Role and Interdependence of Oxidative Stress and Inflammation in Liver Diseases

The crucial roles of oxidative stress and inflammation in the development of hepatic diseases have been unraveled and emphasized for decades. From steatosis to fibrosis, cirrhosis and liver cancer, hepatic oxidative stress, and inflammation are sustained and participated in this pathological progressive process. Notably, increasing evidences showed that oxidative stress and inflammation are tightly related, which are regarded as essential partners that present simultaneously and interact with each other in various pathological conditions, creating a vicious cycle to aggravate the hepatic diseases. Clarifying the interaction of oxidative stress and inflammation is of great importance to provide new directions and targets for developing therapeutic intervention. Herein, this review is concerned with the regulation and interdependence of oxidative stress and inflammation in a variety of liver diseases. In addition to classical mediators and signaling, particular emphasis is placed upon immune suppression, a potential linkage of oxidative stress and inflammation, to provide new inspiration for the treatment of liver diseases. Furthermore, since antioxidation and anti-inflammation have been extensively attempted as the strategies for treatment of liver diseases, the application of herbal medicines and their derived compounds that protect liver from injury via regulating oxidative stress and inflammation collectively were reviewed and discussed.

Colonic and Hepatic Modulation by Lipoic Acid and/or N-Acetylcysteine Supplementation in Mild Ulcerative Colitis Induced by Dextran Sodium Sulfate in Rats

Lipoic acid (LA) and N-acetylcysteine (NAC) are antioxidant and anti-inflammatory agents that have not yet been tested on mild ulcerative colitis (UC). This study aims to evaluate the action of LA and/or NAC, on oxidative stress and inflammation markers in colonic and hepatic rat tissues with mild UC, induced by dextran sodium sulfate (DSS) (2% w/v). LA and/or NAC (100 mg·kg·day^-1, each) were given, once a day, in the diet, in a pretreatment phase (7 days) and during UC induction (5 days). Colitis induction was confirmed by histological and biochemical analyses (high performance liquid chromatography, spectrophotometry, and Multiplex®). A redox imbalance occurred before an immunological disruption in the colon. NAC led to a decrease in hydrogen peroxide (H₂O₂), malondialdehyde (MDA) levels, and myeloperoxidase activity. In the liver, DSS did not cause damage but treatments with both antioxidants were potentially harmful, with LA increasing MDA and LA + NAC increasing H₂O₂, tumor necrosis factor alpha, interferon gamma, and transaminases. In summary, NAC exhibited the highest colonic antioxidant and anti-inflammatory activity, while LA + NAC caused hepatic damage.

LPS-Induced Macrophage Activation and Plasma Membrane Fluidity Changes are Inhibited Under Oxidative Stress

Macrophage activation is essential for a correct and efficient response of innate immunity. During oxidative stress membrane receptors and/or membrane lipid dynamics can be altered, leading to dysfunctional cell responses. Our aim is to analyze membrane fluidity modifications and cell function under oxidative stress in LPS-activated macrophages. Membrane fluidity of individual living THP-1 macrophages was evaluated by the technique two-photon microscopy. LPS-activated macrophage function was determined by TNFα secretion. It was shown that LPS activation causes fluidification of macrophage plasma membrane and production of TNFα. However, oxidative stress induces rigidification of macrophage plasma membrane and inhibition of cell activation, which is evidenced by a decrease of TNFα secretion. Thus, under oxidative conditions macrophage proinflammatory response might develop in an inefficient manner.

Effect of shikonin on concanavalin A-induced liver injury and possible mechanisms involved

AIM

To investigate the effect of shikonin on concanavalin A (Con A)-induced acute liver injury in mice and explore the underlying mechanisms.

METHODS

Acute liver injury was induced by Con A in Balb/c mice through tail injection. The mice were randomly divided into five groups of fourteen mice as follows: (1) normal group; (2) Con A-induced model group; (3) low-dose (12.5 mg/kg) shikonin + Con A group; (4) medium-dose (25 mg/kg) shikonin + Con A group; (5) high-dose (50 mg/kg) shikonin + Con A group. Histological grading and the measurement of the levels of alanine transaminase (ALT), aspartate transaminase (AST), nitric oxide (NO), inducible nitric oxide synthase (iNOS), nuclear factor-κB (NF-κB), IκBα and IκBβ were performed.

RESULTS

Compared to the normal group, the histological grade as well as the levels of ALT, AST, NO, iNOS and NF-κB significantly increased in the model group, but the levels of IκBα and IκBβ were decreased. After shikonin (50 mg/kg) treatment, the histological grade and the levels of ALT, AST, NO, iNOS and NF-κB significantly were decreased, and the levels of IκBα and IκBβ were increased. The doses of 12.5 mg/kg and 25 mg/kg worked inefficiently.

CONCLUSION

Shikonin (50 mg/kg) protects against Con A-induced liver injury by decreasing the level of NO, which may correlate with the amelioration of NF-κB activity.

The Effects of Subchronic Methionine Overload Administered Alone or Simultaneously with L-cysteine or N-acetyl-L-cysteine on Body Weight, Homocysteine Levels and Biochemical Parameters in the Blood of Male Wistar Rats

Hyperhomocysteinemia (HHC), both basal and after methionine load, may occur due to genetic disorders or deficiencies of nutrients that affect the remethylation or trans-sulphuration pathways during methionine metabolism. HHC is involved in the pathogenesis of many illnesses as a result of its prooxidative effect and its impairment of antioxidative protection. The aim was to examine the effects of subchronic methionine overload on the body weight and standard biochemical parameters in rat serum and to examine whether simultaneous subchronic intraperotoneal administration of methionine alone or together with L-cysteine or N-acetyl-cysteine resulted in a change in the body weight and biochemical parameters in the rat serum. The research was conducted during a three-week period (male Wistar albino rats, n=36, body weight of approximately 160 g, age of 15-20 days), and the animals were divided into a control group and three experimental groups of 8-10 animals each: a) control group (0.9% sodium chloride 0.1-0.2 ml/day); b) methionine (0.8 mmol/kg/bw/day) (MET group); c) methionine (0.8 mmol/kg/bw/day) + L-cysteine (7 mg/kg/bw/day) (L-cys+MET group); and d) methionine (0.8 mmol/kg/bw/day) + N-acetyl-L-cysteine (50 mg/kg/bw/day) (NAC+MET group). In addition to the body weight monitoring, the levels of total homocysteine and the standard biochemical parameters in blood samples (plasma or serum) were determined. The results indicated that monitoring the homocysteine levels and standard biochemical parameters in blood could be used for analysis and could provide an excellent guideline for distinguishing between toxic and non-toxic doses of methionine intake, which may be meaningful for clinical applications.

Disulfide stress in carbon monoxide poisoning

OBJECTIVES

Carbon monoxide (CO) remains the most common cause of lethal poisoning around the world. The purpose of this study was to investigate the homeostasis between thiol-disulfide couples and to evaluate oxidative status comprehensively in acute CO poisoning, using new parameters along with other well-known oxidant-antioxidant molecules.

DESIGN AND METHODS

This case study consisted of 43 subjects who were diagnosed with carbon monoxide poisoning and 35 healthy individuals who were used as controls. Thiol-disulfide paired tests were examined in both groups using the method developed recently.

RESULTS

Patients with CO poisoning had significantly higher levels of serum disulfide than the control patients (20.7±5.03 versus 16.43±3.97, p=0.001). Native thiol and total thiol levels were lower in the CO patient group than in the control group (p<0.001, for each variable). The disulfide/native thiol ratios and disulfide/total thiol ratios were significantly higher, while native thiol/total thiol ratios were significantly lower, in patients with acute CO poisoning than in the healthy controls (p<0.001, for all ratios). The disulfide/native ratios were negatively correlated with both total antioxidant response and paraoxonase and arylesterase values and were positively correlated with total oxidant status and ceruloplasmin values (p<0.05, for all correlations).

CONCLUSIONS

Excessive disulfide levels and their related ratios were found in CO poisoning patients. In particular, the disulfide/native thiol ratio was identified as an indicator for overall oxidative status. Among CO poisoning patients, the thiol-disulfide balance was found to be impaired. Therefore, the disruption of thiol-disulfide homeostasis might be involved in CO toxicity.

Acetaminophen-Induced Hepatotoxicity: a Comprehensive Update

Hepatic injury and subsequent hepatic failure due to both intentional and non-intentional overdose of acetaminophen (APAP) has affected patients for decades, and involves the cornerstone metabolic pathways which take place in the microsomes within hepatocytes. APAP hepatotoxicity remains a global issue; in the United States, in particular, it accounts for more than 50% of overdose-related acute liver failure and approximately 20% of the liver transplant cases. The pathophysiology, disease course and management of acute liver failure secondary to APAP toxicity remain to be precisely elucidated, and adverse patient outcomes with increased morbidity and mortality continue to occur. Although APAP hepatotoxicity follows a predictable timeline of hepatic failure, its clinical presentation might vary. N-acetylcysteine (NAC) therapy is considered as the mainstay therapy, but liver transplantation might represent a life-saving procedure for selected patients. Future research focus in this field may benefit from shifting towards obtaining antidotal knowledge at the molecular level, with focus on the underlying molecular signaling pathways.

Genetic polymorphisms in the promoter region of catalase gene, creates new potential PAX-6 and STAT4 response elements

Catalase (CAT, OMIM: 115500) is an endogenous antioxidant enzyme and genetic variations in the regulatory regions of the CAT gene may alter the CAT enzyme activity and subsequently may alter the risk of oxidative stress related disease. In this study, potential influence(s) of the A-21T (rs7943316) and C-262T (rs1001179) genetic polymorphisms in the CAT promoter region, using the ALGGEN-PROMO.v8.3 online software were analyzed. Our findings show that the A allele at the -21 position creates a new potential binding site for PAX-6 and the T allele at the -262 position changes the TFII-I binding site into STAT4 response element. The PAX-6 and STAT4 are the multifunctional and enhancing transcription factors.

Retinol-Binding Protein 4 Induces Cardiomyocyte Hypertrophy by Activating TLR4/MyD88 Pathway

Insulin resistance plays a major role in the development and progression of cardiac hypertrophy and heart failure. Heart failure in turn promotes insulin resistance and increases the risk for diabetes. The vicious cycle determines significant mortality in patients with heart failure and diabetes. However, the underlying mechanisms for the vicious cycle are not fully elucidated. Here we show that circulating levels and adipose expression of retinol-binding protein 4 (RBP4), an adipokine that contributes to systemic insulin resistance, were elevated in cardiac hypertrophy induced by transverse aortic constriction and angiotensin-II (Ang-II) infusion. Ang-II increased RBP4 expression in adipocytes, which was abolished by losartan, an Ang-II receptor blocker. The elevated RBP4 in cardiac hypertrophy may have pathophysiological consequences because RBP4 increased cell size, enhanced protein synthesis, and elevated the expression of hypertrophic markers including Anp, Bnp, and Myh7 in primary cardiomyocytes. Mechanistically, RBP4 induced the expression and activity of toll-like receptor 4 (TLR4) and myeloid differentiation primary response gene 88 (MyD88) in cardiomyocytes, resulting in enhanced inflammation and reactive oxygen species production. Inhibition or knockdown of the TLR4/MyD88 pathway attenuated inflammatory and hypertrophic responses to RBP4 stimulation. Importantly, RBP4 also reduced the expression of glucose transporter-4 and impaired insulin-stimulated glucose uptake in cardiomyocytes. This impairment was ameliorated in cardiomyocytes from TLR4 knockout mice. Therefore, RBP4 may be a critical modulator promoting the vicious cycle of insulin resistance and heart failure by activating TLR4/MyD88-mediated inflammatory pathways. Potentially, lowering RBP4 might break the vicious cycle and improve both insulin resistance and cardiac hypertrophy.

Molecular cloning, characterization, and the response of Cu/Zn superoxide dismutase and catalase to PBDE-47 and -209 from the freshwater bivalve Anodonta woodiana

Polybrominated diphenyl ethers-47 (PBDE-47) and -209 are significant components of total PBDEs in water and can catalyze the production of reactive oxygen species (ROS) in the organisms. Anti-oxidant enzymes play an important role in scavenging the high level of ROS. In the current study, two full-length cDNAs of Cu/Zn superoxide dismutase (CuZnSODs) and catalase (CAT) were isolated from freshwater bivalve Anodonta woodiana by rapid amplification of cDNA ends approach and respectively named as AwSOD and AwCAT. The nucleotide sequence of AwSOD cDNA had an open reading frame (ORF) of 465 bp encoding a polypeptide of 155 amino acids in which signature 1 GKHGFHVHEFGDNT and signature 2 GNAGARSACGVI of SODs were observed. Deduced amino acid sequence of AwSOD showed a significant similarity with that of CuZnSODs. AwCAT had an ORF 1536 bp encoding a polypeptide of 512 amino acids which contains a conserved catalytic site motif, and a proximal heme-ligand signature motif of CATs. The time-course expressions of AwSOD and AwCAT in hepatopancreas were measured by quantitative real-time PCR. Expressions of AwSOD and AwCAT showed a significant up-regulation in groups at a low concentration treatment of PBDE-47, a biphasic pattern in groups with a high concentration treatment. Administration of PBDE-209 could result in an up-regulation of AwSOD and AwCAT expressions with time- and dose-dependent matter. These results indicate that up-regulations of AwSOD and AwCAT expression of hepatopancreas of freshwater bivalve A. woodiana contribute to eliminate oxidative stress derived from PBDE-47 and -209 treated.