Vitamin E reduces oxidant injury to mitochondria and the hepatotoxicity of taurochenodeoxycholic acid in the rat

Forsythiaside-A improved bile-duct-ligation-induced liver fibrosis in mice: The involvement of alleviating mitochondrial damage and ferroptosis in hepatocytes via activating Nrf2

Liver fibrosis is a key and reversible stage in the progression of many chronic liver diseases to cirrhosis or hepatocellular carcinoma. Forsythiaside-A (FTA), a main compound isolated from Forsythiae Fructus, has an excellent liver protective activity. This study aims to investigate the efficacy of FTA in improving cholestatic liver fibrosis. Bile-duct-ligation (BDL) was conducted to induce liver fibrosis in mice. Hepatic collagen deposition was evaluated by Masson and Sirus red staining. The bile acid spectrum in the liver and serum was analyzed by mass spectrometry. Liver oxidative stress injury and mitochondria damage were observed by using Mito-Tracker Red fluorescence staining, transmission electron microscopy, etc. The level of ferrous iron (Fe2+) and the expression of ferroptosis-associated molecules were detected. The binding between FTA and its target protein was confirmed by Co-immunoprecipitation (Co-IP), cellular thermal shift assay (CETSA), drug affinity responsive target stability (DARTS) and surface plasmon resonance (SPR). Our results demonstrated that FTA alleviated BDL-induced liver fibrosis in mice. FTA did not decrease the elevated amount of bile acids in BDL-treated mice, but reduced the bile acid-induced mitochondrial damage, oxidative stress and ferroptosis in hepatocytes, and also induced nuclear factor erythroid 2-related factor-2 (Nrf2) activation. In Nrf2 knock-out mice, the FTA-provided protection against BDL-induced liver fibrosis was disappeared, and FTA's inhibition on mitochondrial damage, oxidative stress and ferroptosis were lowered. Further results displayed that FTA could directly bind to Kelch-like ECH-associated protein-1 (Keap1), thereby activating Nrf2. Moreover, the BDL-induced liver fibrosis was markedly weakened in liver-specific Keap1 knockout mice. Hence, this study suggests that FTA alleviated the BDL-induced liver fibrosis through attenuating mitochondrial damage and ferroptosis in hepatocytes by activating Nrf2 via directly binding to Keap1.

Pediatric Autoimmune or Primary Sclerosing Cholangitis: Metronidazole Effectiveness on Biochemical Data, Bile Acid Profile, and Gut Microbiota: A Pilot Study

Objectives

Autoimmune hepatitis and primary sclerosing cholangitis (PSC) can both be present, resulting in autoimmune sclerosing cholangitis (ASC). PSC physiopathology could be based on the cross-talk between gut microbiota and bile acids (BAs); antibiotics are an innovative therapy. This pilot study assesses metronidazole (MTZ)'s effectiveness in ASC or PSC patients according to the stage of the disease, and its effects on biochemical parameters, BA profiles, and gut microbiota.

Methods

ASC or PSC patients from Cliniques universitaires Saint-Luc's pediatric hepato-gastroenterology division were enrolled retrospectively and prospectively; both datasets were merged. MTZ was administered over at least 14 days on top of standard treatment (ursodeoxycholic acid, azathioprine, and steroids). Fecal and blood samples were collected before (T0) and at MTZ day 14 (T14). Sustained biochemical remission was defined by the reduction of transaminases (AST and ALT), gamma-glutamyl transferase (GGT), and CRP until 12 months post-MTZ.

Results

A total of 18 patients (mean age, 13.2 ± 4.5 years) were enrolled (13 ASC and 5 PSC), and divided in remission or relapse patients. CRP, AST, ALT, and GGT levels decreased post-MTZ in both groups (excepting GGT in relapse patients), with decreases between T0 and T14 being significant for AST and ALT. Relapse patients were older (P = 0.0351) and in late-disease stage, with mainly large-duct PSC (P = 0.0466). In remission patients, the mean plasma relative abundance of hydrophilic BA increased by +6.3% (P = 0.0391) after MTZ. Neither at baseline nor T14, there were significant differences in gut microbiota recorded.

Conclusion

These data are likely indicative of long-term benefits following MTZ therapy at early-stage ASC or PSC, with increased hydrophilic BA abundance. Multicenter prospective studies are needed.

Potential biomarkers screening of Polygonum multiflorum radix-induced liver injury based on metabonomics analysis of clinical samples

ETHNOPHARMACOLOGICAL RELEVANCE

Polygonum multiflorum Radix (PMR) is the dried root tuber of Polygonum multiflorum Thunb., which has been used in the clinic for a variety of pharmacological activities. However, Polygonum multiflorum Radix-induced liver injury (PMR-ILI) has been reported in recent years, which has limited its clinical use to some extent. The occurrence of PMR-ILI is not universal, so finding the different metabolic characteristics between PMR-ILI and Polygonum multiflorum Radix-tolerance group (PMR-T) is very important for the PMR rational clinical application and PMR-ILI early clinical diagnosis.

METHODS

In this study, 6 clinical plasma samples of PMR-ILI and 13 PMR-T were collected and analyzed by high-resolution liquid chromatography-mass spectrometry. Firstly, the differential metabolites of the two groups were screened by conventional screening methods such as multivariate statistical analysis. Secondly, the characteristic metabolites with greater contribution, correlation with liver injury and high sensitivity were screened by correlation analysis with clinical liver injury indicators, random forest analysis, and receiver operating characteristic curve (ROC).

RESULTS

After multivariate statistical analysis and screening analysis, 29 differential metabolites were identified. Compared with PMR-T group, the metabolism of glycerol and phospholipid, glutamine and glutamate, phenylalanine, sphingolipid and tryptophan in PMR-ILI group were disturbed. After correlation analysis with liver injury indexes and random forest screening, 8 potential biomarkers closely related to clinical liver injury were obtained. Finally, 3 potential biomarkers with high expression in PMR-ILI, hypoxanthine, LysoPC(P-16:0/0:0) and taurochenodesoxycholic acid, were screened out through the analysis of ROC, which can provide a basis for the early clinical diagnosis.

CONCLUSION

Based on the analysis of the PMR-ILI and PMR-T plasma samples by LC-MS, three biomarkers of clinical liver injury of Polygonum multiflorum Radix were selected: hypoxanthine, LysoPC(P-16:0/0:0) and taurochenodeoxycholic acid.

The altered lipidome of hepatocellular carcinoma

Alterations in metabolic pathways are a hallmark of cancer. A deeper understanding of the contribution of different metabolites to carcinogenesis is thus vitally important to elucidate mechanisms of tumor initiation and progression to inform therapeutic strategies. Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide and its altered metabolic landscape is beginning to unfold with the advancement of technologies. In particular, characterization of the lipidome of human HCCs has accelerated, and together with biochemical analyses, are revealing recurrent patterns of alterations in glycerophospholipid, sphingolipid, cholesterol and bile acid metabolism. These widespread alterations encompass a myriad of lipid species with numerous roles affecting multiple hallmarks of cancer, including aberrant growth signaling, metastasis, evasion of cell death and immunosuppression. In this review, we summarize the current trends and findings of the altered lipidomic landscape of HCC and discuss their potential biological significance for hepatocarcinogenesis.

Bone morphogenetic protein 2 is a new molecular target linked to non-alcoholic fatty liver disease with potential value as non-invasive screening tool

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is the commonest cause of chronic liver disease worldwide, being non-alcoholic steatohepatitis (NASH) its most clinically relevant form. Given the risks associated with taking a liver biopsy, the design of accurate non-invasive methods to identify NASH patients is of upmost importance. BMP2 plays a key role in metabolic homeostasis; however, little is known about its involvement in NAFLD onset and progression. This study aimed to elucidate the impact of BMP2 in NAFLD pathophysiology.

METHODS

Hepatic and circulating levels of BMP2 were quantified in serum and liver specimens from 115 biopsy-proven NAFLD patients and 75 subjects with histologically normal liver (NL). In addition, BMP2 content and release was determined in cultured human hepatocytes upon palmitic acid (PA) overload.

RESULTS

We found that BMP2 expression was abnormally increased in livers from NAFLD patients than in subjects with NL and this was reflected in higher serum BMP2 levels. Notably, we observed that PA upregulated BMP2 expression and secretion by human hepatocytes. An algorithm based on serum BMP2 levels and clinically relevant variables to NAFLD showed an AUROC of 0.886 (95%CI, 0.83-0.94) to discriminate NASH. We used this algorithm to develop SAN (Screening Algorithm for NASH): a SAN < 0.2 implied a low risk and a SAN ≥ 0.6 indicated high risk of NASH diagnosis.

CONCLUSION

This proof-of-concept study shows BMP2 as a new molecular target linked to NAFLD and introduces SAN as a simple and efficient algorithm to screen individuals at risk for NASH.

Mitochondria homeostasis: Biology and involvement in hepatic steatosis to NASH

Mitochondrial biology and behavior are central to the physiology of liver. Multiple mitochondrial quality control mechanisms remodel mitochondrial homeostasis under physiological and pathological conditions. Mitochondrial dysfunction and damage induced by overnutrition lead to oxidative stress, inflammation, liver cell death, and collagen production, which advance hepatic steatosis to nonalcoholic steatohepatitis (NASH). Accumulating evidence suggests that specific interventions that target mitochondrial homeostasis, including energy metabolism, antioxidant effects, and mitochondrial quality control, have emerged as promising strategies for NASH treatment. However, clinical translation of these findings is challenging due to the complex and unclear mechanisms of mitochondrial homeostasis in the pathophysiology of NASH.

Bile Acids Activate NLRP3 Inflammasome, Promoting Murine Liver Inflammation or Fibrosis in a Cell Type-Specific Manner

Bile acids (BA) as important signaling molecules are considered crucial in development of cholestatic liver injury, but there is limited understanding on the involved cell types and signaling pathways. The aim of this study was to evaluate the inflammatory and fibrotic potential of key BA and the role of distinct liver cell subsets focusing on the NLRP3 inflammasome. C57BL/6 wild-type (WT) and Nlrp3^−/− mice were fed with a diet supplemented with cholic (CA), deoxycholic (DCA) or lithocholic acid (LCA) for 7 days. Additionally, primary hepatocytes, Kupffer cells (KC) and hepatic stellate cells (HSC) from WT and Nlrp3^−/− mice were stimulated with aforementioned BA ex vivo. LCA feeding led to strong liver damage and activation of NLRP3 inflammasome. Ex vivo KC were the most affected cells by LCA, resulting in a pro-inflammatory phenotype. Liver damage and primary KC activation was both ameliorated in Nlrp3-deficient mice or cells. DCA feeding induced fibrotic alterations. Primary HSC upregulated the NLRP3 inflammasome and early fibrotic markers when stimulated with DCA, but not LCA. Pro-fibrogenic signals in liver and primary HSC were attenuated in Nlrp3^−/− mice or cells. The data shows that distinct BA induce NLRP3 inflammasome activation in HSC or KC, promoting fibrosis or inflammation.

FXR-Deoxycholic Acid-TNF-α Axis Modulates Acetaminophen-Induced Hepatotoxicity

The idiosyncratic characteristics and severity of acetaminophen (APAP) overdose-induced hepatotoxicity render identifying the predisposing factors and mechanisms of APAP-induced liver toxicity necessary and urgent. Farnesoid X receptor (FXR) controls bile acid homeostasis and modulates the progression of various liver diseases. Although global FXR deficiency in mice enhances APAP intoxication, the mechanism remains elusive. In this study, an increased sensitivity to APAP-induced toxicity was found in global Fxr-null (Fxr-/-) mice, but was not observed in hepatocyte-specific or macrophage-specific Fxr-null mice, suggesting that global FXR deficiency enhances APAP hepatotoxicity via disruption of systematic bile acid homeostasis. Indeed, more bile acid accumulation was found in global Fxr-/- mice, while 2% cholestyramine diet feeding decreased serum bile acids and alleviated APAP hepatotoxicity in global Fxr-/- mice, suggesting that bile acid accumulation contributes to APAP toxicity. Bile acids were suspected to induce macrophage to release tumor necrosis factor-α (TNF-α), which is known to enhance the APAP hepatotoxicity. In vitro, deoxycholic acid (DCA), a secondary bile acid metabolite, significantly induced Tnfa mRNA and dose-dependently enhanced TNF-α release from macrophage, while the same dose of DCA did not directly potentiate APAP toxicity in cultured primary hepatocytes. In vivo, DCA enhanced TNF-α release and potentiated APAP toxicity, both of which were abolished by the specific TNF-α antagonist infliximab. These results reveal an FXR-DCA-TNF-α axis that potentiates APAP hepatotoxicity, which could guide the clinical safe use of APAP.

Changes in Glutathione Content in Liver Diseases: An Update

Glutathione (GSH), a tripeptide particularly concentrated in the liver, is the most important thiol reducing agent involved in the modulation of redox processes. It has also been demonstrated that GSH cannot be considered only as a mere free radical scavenger but that it takes part in the network governing the choice between survival, necrosis and apoptosis as well as in altering the function of signal transduction and transcription factor molecules. The purpose of the present review is to provide an overview on the molecular biology of the GSH system; therefore, GSH synthesis, metabolism and regulation will be reviewed. The multiple GSH functions will be described, as well as the importance of GSH compartmentalization into distinct subcellular pools and inter-organ transfer. Furthermore, we will highlight the close relationship existing between GSH content and the pathogenesis of liver disease, such as non-alcoholic fatty liver disease (NAFLD), alcoholic liver disease (ALD), chronic cholestatic injury, ischemia/reperfusion damage, hepatitis C virus (HCV), hepatitis B virus (HBV) and hepatocellular carcinoma. Finally, the potential therapeutic benefits of GSH and GSH-related medications, will be described for each liver disorder taken into account.

Treatment and protective effects of metalloproteinase inhibitors alone and in combination with N-Acetyl cysteine plus vitamin E in rats exposed to aflatoxin B1

This study was conducted to investigate the effects of matrix metalloproteinase (MMP) inhibitors dexamethasone and minocycline administrations -both single and in combination with N-acetylcysteine (NAC) and vitamin E-on the tissue distribution and lethal dose (LD)₅₀ of aflatoxin (AF)B₁ in rats. We performed this study on male Wistar rats (8-10 weeks) in two phases. In the first phase, rats were administered dexamethasone (5 and 20 mg/kg) and minocycline (45 and 90 mg/kg), both as single treatments and in combination with NAC (200 mg/kg) and vitamin E (600 mg/kg); these treatments followed AFB₁ administration (2 mg/kg). In the second phase, the therapeutic effect value (TEV) was calculated to determine the treatment effect on the LD₅₀ level of AFB₁. The tissue affinity of AFB1 from high to low was liver, kidney, intestine, brain, heart, spleen, lung, testis, and vitreous humor, respectively. Dexamethasone at the 20 mg/kg dose significantly reduced AFB₁ concentrations in the plasma and the other tissues, except for the vitreous humor. The effects of minocycline on the plasma and tissue concentrations of AFB₁ varied by dose and tissue. The combinations of dexamethasone or minocycline with NAC and vitamin E increased the AFB₁ concentrations in the plasma and all tissues, except for vitreous humor and liver. In male rats, the LD₅₀ value of AFB₁ was 11.86 mg/kg. The TEV of dexamethasone (20 mg/kg) was calculated to be 1.5. Dexamethasone can be administered in repeated doses at ≥20 mg/kg to increase survival in AFB₁ poisoning.

Current treatment paradigms and emerging therapies for NAFLD/NASH

Non-alcoholic fatty liver disease (NAFLD) is one the fastest emerging manifestations of the metabolic syndrome worldwide. Non-alcoholic steatohepatitis (NASH), the progressive form of NAFLD, may culminate into cirrhosis and hepatocellular cancer (HCC) and is presently a leading cause of liver transplant. Although a steady progress is seen in understanding of the disease epidemiology, pathogenesis and identifying therapeutic targets, the slowest advancement is seen in the therapeutic field. Currently, there is no FDA approved therapy for this disease and appropriate therapeutic targets are urgently warranted. In this review we discuss the role of lifestyle intervention, pharmacological agents, surgical approaches, and gut microbiome, with regard to therapy for NASH. In particular, we focus the role of insulin sensitizers, thyroid hormone mimetics, antioxidants, cholesterol lowering drugs, incretins and cytokines as therapeutic targets for NASH. We highlight these targets aiming to optimize the future for NASH therapy.

Astaxanthin attenuates d-galactose-induced brain aging in rats by ameliorating oxidative stress, mitochondrial dysfunction, and regulating metabolic markers

Astaxanthin (AX) is a red-colored xanthophyll carotenoid with potent antioxidant, anti-inflammatory, and neuroprotective properties. However, the underlying in vivo mechanism by which AX protects the brain from oxidative stress remains unclear. In this study, we investigated the protective effect of AX on brain oxidative damage in a d-galactose-induced rat model of aging. We also explored its possible mechanism of action by analyzing the resulting serum metabolic profiles. Our results showed that AX significantly increased the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) by 26%, 30%, and 53%, respectively. AX also significantly increased the mitochondrial membrane potential by 18% when compared with the model group. Additionally, treatment with AX (15 mg kg^-1) increased the activities of respiratory chain complexes I and IV by 50.17% and 122.87%, respectively. Furthermore, AX also improved age-related morphological changes in the cerebral cortex and hippocampus. Significant differences in serum metabolic profiles were observed between the d-galactose and AX treatment groups. AX corrected amino acid metabolic problems by increasing the levels of N-acetyl-l-leucine, N-acetyl-l-tyrosine, and methionine sulfoxide to protect nerve cells. This also allowed AX to regulate the pentose phosphate pathway by acting on ergotoxine, d-xylose-5-phosphoric, and thiamine, to against oxidative stress and apoptosis. Moreover, AX reduced the levels of both hyodeoxycholic acid and chenodeoxycholic acid though the primary bile acid biosynthesis pathway, resulting in improved brain mitochondrial dysfunction. In conclusion, AX likely enhances the brain's antioxidant defenses through these potential metabolic means, enabling the brain to resist mitochondrial dysfunction, improve neuronal damage, and protect the electron transmission of mitochondrial respiratory chain, thus preventing brain aging.

Inhibitory Effect of Sestrin 2 on Hepatic Stellate Cell Activation and Liver Fibrosis

Aims: Hepatic fibrosis results from chronic liver injury and inflammatory responses. Sestrin 2 (Sesn2), an evolutionarily conserved antioxidant enzyme, reduces the severities of acute hepatitis and metabolic liver diseases. However, the role of Sesn2 in the pathogenesis of liver fibrosis remains obscure. Here, we used cultured hepatic stellate cells (HSCs) and chronic carbon tetrachloride (CCl₄) and bile duct ligation (BDL) murine models to investigate the effects of Sesn2 on fibrogenesis. Results: Sesn2 protein and mRNA levels were upregulated in activated primary HSCs, and by increasing transcription, transforming growth factor-β (TGF-β) also increased Sesn2 expression in HSCs. Furthermore, Smad activation was primarily initiated by TGF-β signaling, and Smad3 activation increased Sesn2 luciferase activity. In silico analysis of the 5' upstream region of the Sesn2 gene revealed a putative Smad-binding element (SBE), and its deletion demonstrated that the SBE between -964 and -956 bp within human Sesn2 promoter was critically required for TGF-β-mediated response. Moreover, ectopic expression of Sesn2 reduced gene expressions associated with HSC activation, and this was accompanied by marked decreases in SBE luciferase activity and Smad phosphorylation. Infection of recombinant adenovirus Sesn2 reduced hepatic injury severity, as evidenced by reductions in CCl₄- or BDL-induced alanine aminotransferase and aspartate aminotransferase, and inhibited collagen accumulation. Furthermore, HSC-specific lentiviral delivery of Sesn2 prevented CCl₄-induced liver fibrosis. Finally, Sesn2 expression was downregulated in the livers of patients with liver cirrhosis and in mouse models of hepatic fibrosis. Innovation and Conclusion: Our findings suggest that Sesn2 has the potential to inhibit HSC activation and hepatic fibrosis.

Altered bile acid profile in mild cognitive impairment and Alzheimer's disease: Relationship to neuroimaging and CSF biomarkers

INTRODUCTION

Bile acids (BAs) are the end products of cholesterol metabolism produced by human and gut microbiome co-metabolism. Recent evidence suggests gut microbiota influence pathological features of Alzheimer's disease (AD) including neuroinflammation and amyloid-β deposition.

METHOD

Serum levels of 20 primary and secondary BA metabolites from the AD Neuroimaging Initiative (n = 1562) were measured using targeted metabolomic profiling. We assessed the association of BAs with the "A/T/N" (amyloid, tau, and neurodegeneration) biomarkers for AD: cerebrospinal fluid (CSF) biomarkers, atrophy (magnetic resonance imaging), and brain glucose metabolism ([18F]FDG PET).

RESULTS

Of 23 BAs and relevant calculated ratios after quality control procedures, three BA signatures were associated with CSF Aβ1-42 ("A") and three with CSF p-tau181 ("T") (corrected P < .05). Furthermore, three, twelve, and fourteen BA signatures were associated with CSF t-tau, glucose metabolism, and atrophy ("N"), respectively (corrected P < .05).

DISCUSSION

This is the first study to show serum-based BA metabolites are associated with "A/T/N" AD biomarkers, providing further support for a role of BA pathways in AD pathophysiology. Prospective clinical observations and validation in model systems are needed to assess causality and specific mechanisms underlying this association.

Stressing the (Epi)Genome: Dealing with Reactive Oxygen Species in Cancer

SIGNIFICANCE

Growing evidence indicates cross-talk between reactive oxygen species (ROS) and several key epigenetic processes such as DNA methylation, histone modifications, and miRNAs in normal physiology and human pathologies including cancer. This review focuses on how ROS-induced oxidative stress, metabolic intermediates, and epigenetic processes influence each other in various cancers. Recent Advances: ROS alter chromatin structure and metabolism that impact the epigenetic landscape in cancer cells. Several site-specific DNA methylation changes have been identified in different cancers and are discussed in the review. We also discuss the interplay of epigenetic enzymes and miRNAs in influencing malignant transformation in an ROS-dependent manner.

CRITICAL ISSUES

Loss of ROS-mediated signaling mostly by epigenetic regulation may promote tumorigenesis. In contrast, augmented oxidative stress because of high ROS levels may precipitate epigenetic alterations to effect various phases of carcinogenesis. We address both aspects in the review.

FUTURE DIRECTIONS

Several drugs targeting ROS are under various stages of clinical development. Recent analysis of human cancers has revealed pervasive deregulation of the epigenetic machinery. Thus, a better understanding of the cross-talk between ROS and epigenetic alterations in cancer could lead to the identification of new drug targets and more effective treatment modalities.

Role of gut microbiota and oxidative stress in the progression of non-alcoholic fatty liver disease to hepatocarcinoma: Current and innovative therapeutic approaches

Non-alcoholic fatty liver disease (NAFLD) represents the most common chronic liver disease in industrialized countries. NAFLD progresses through the inflammatory phase of non-alcoholic steatohepatitis (NASH) to fibrosis and cirrhosis, with some cases developing liver failure or hepatocellular carcinoma (HCC). Liver biopsy remains the gold standard approach to a definitive diagnosis of NAFLD and the distinction between simple steatosis and NASH. The pathogenesis of NASH is still not clear. Several theories have been proposed ranging from the "Two Hit Theory" to the "Multiple Hit Theory". However, the general consensus is that the gut microbiota, oxidative stress, and mitochondrial damage play key roles in the pathogenesis of NASH. The interaction between the gut epithelia and some commensal bacteria induces the rapid generation of reactive oxygen species (ROS). The main goal of any therapy addressing NASH is to reverse or prevent progression to liver fibrosis/cirrhosis. This problem represents the first "Achilles' heel" of the new molecules being evaluated in most ongoing clinical trials. The second is the inability of these molecules to reach the mitochondria, the primary sites of energy production and ROS generation. Recently, a variety of non-pharmacological and pharmacological treatment approaches for NASH have been evaluated including vitamin E, the thiazolidinediones, and novel molecules related to NASH pathogenesis (including obeticholic acid and elafibranor). Recently, a new isoform of human manganese superoxide dismutase (MnSOD) was isolated and obtained in a synthetic recombinant form designated rMnSOD. This protein has been shown to be a powerful antioxidant capable of mediating ROS dismutation, penetrating biological barriers via its uncleaved leader peptide, and reducing portal hypertension and fibrosis in rats affected by liver cirrhosis. Based on these distinctive characteristics, it can be hypothesized that this novel recombinant protein (rMnSOD) potentially represents a new and highly efficient adjuvant therapy to counteract the progression from NASH to HCC.

Haptoglobin Genotype and Vitamin E Versus Placebo for the Treatment of Nondiabetic Patients with Nonalcoholic Steatohepatitis in China: A Multicenter, Randomized, Placebo-Controlled Trial Design

INTRODUCTION

Vitamin E is one of the most promising agents for nonalcoholic steatohepatitis (NASH) treatment, and its drug responsiveness may be closely associated with haptoglobin (Hp) genotype. However, its efficacy and safety remain unknown in China. This clinical trial of vitamin E versus placebo for the treatment of nondiabetic patients with nonalcoholic steatohepatitis (VENS) is conducted to evaluate (a) the efficacy and safety of treatment with vitamin E softgel (300 mg/day) determined from standardized histologic scoring of liver biopsies, (b) whether treatment with vitamin E improves biochemical parameters, cytokines, anthropometric parameters, controlled attenuation parameter (CAP), and transient elastography (TE) values determined by Fibroscan and health-related quality of life (SF-36), (c) whether the efficacy of vitamin E treatment is associated with the Hp genotype in nondiabetic adults with NASH.

METHODS

VENS is a multicenter, randomized, double-masked, placebo parallel controlled trial to evaluate the efficacy and safety of treatment with vitamin E softgel in nondiabetic adults with NASH versus treatment with placebo in China. Liver biopsies are read by a pathological evaluation committee independently according to the NASH Clinical Research Network (CRN) scoring system. The NAFLD activity score (NAS) represents the sum of scores for steatosis, lobular inflammation, and hepatocyte ballooning. The definition of histologic improvement requires all three of the following criteria to be met: (a) either improvement in NAS by at least 2 points or post-treatment NAS score no higher than 3, (b) at least 1-point improvement in the score for ballooning, and (c) no worsening of fibrosis stages. We plan to recruit 120 biopsy-proven NASH patients from13 centers in China. Participants will be randomly assigned to groups treated with either with vitamin E (100 mg, tid) or placebo for 96 weeks then followed by 24 weeks of post-treatment observation. Biochemical parameters, cytokines, anthropometric parameters, CAP and TE values, Hp genotype, and several questionnaires will be collected as per the schedule. This protocol was approved by the Ethics Committee of Hangzhou Normal University Affiliated Hospital to ensure patients safety, and R&G Pharmastudies Co., Ltd. was established for monitoring the accumulated interim data to review efficacy and quality of data collection and overall study management.

RESULTS

As a preliminary study, a mobile phone application (app) for lifestyle modification and database recording ( http://laiyivens.365hy.com ) was exploited for every participant. The percentage of NAFLD patients with Hp 2-2 allele is much higher than that of Western patients (65.71% vs 36%, respectively), which suggests that the Chinese benefit more from vitamin E treatment.

CONCLUSION

VENS is the first randomized controlled trial (RCT) to evaluate the efficacy of Vitamin E in treating nondiabetic NASH patients in China.

TRIAL REGISTRATION

This study registered at https://clinicaltrials.gov (registration number: NCT02962297).

FUNDING

Zhejiang Medicine Co., Ltd.

Current Treatment of Nonalcoholic Fatty Liver Disease/Nonalcoholic Steatohepatitis

Treatment of nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH) is focused on patients with NASH because they are at highest risk for progressive liver disease. Current first-line treatment consists of lifestyle modifications. Patients should lose at least 7% to 10% of body weight via a combination of physical exercise and calorie restriction dieting. Surgical or endoscopic surgery for weight loss can be considered in obese patients, depending on degree of excess body weight and comorbidities. There is no currently approved pharmacotherapy for NASH. Vitamin E and pioglitazone have the most evidence of therapeutic efficacy but have limitations. The treatment modality chosen should be individualized.

Tigernut (Cyperus esculentus L.) "milk" as a potent "nutri-drink" for the prevention of acetaminophen-induced hepatotoxicity in a murine model

AIM/BACKGROUND

Given the prevalence of toxicants in foods, beauty products, etc., and the increasing demand for "green" products, there is a need for the development of "nutri-drinks" with hepatoprotective properties. The usefulness of tigernut milk (TNM) in preventing acetaminophen (APAP)-induced liver injury was, therefore, investigated.

MATERIALS AND METHODS

A total of 25 rats were randomized into five equal groups. Four groups were treated with 0, 500, 1000, and 2000 kg/mg body weight (bw) TNM, respectively, per os for 2 weeks before they were challenged with 2500 mg/kg bw APAP. Biochemical markers of hepatotoxicity and oxidative stress were determined in the sera of the rats at the end of the study.

RESULTS

Serum alanine aminotransferase concentrations decreased significantly (P < 0.001) and dose-dependently from 334.3 ± 16.1 in the negative control group to 65.4 ± 8.3 in the 2000 mg/kg bw TNM group. Other studied liver enzymes were similarly dose-dependently reduced. These data are corroborated by histological findings. Superoxide dismutase activity (U/mg protein) was increased significantly (P < 0.001) from 108.0 ± 7.4 in the negative control group to 291.0 ± 11.3 in the 2000 mg/kg bw TNM group, and indeed all the test groups. The malondialdehyde concentrations in the test rats were slightly lower than that of the negative control group.

CONCLUSION

TNM at the tested concentrations significantly prevented liver injury. Phytochemicals in TNM, working directly as antioxidants or indirectly by inducing the synthesis of glutathione, may be responsible for the observed effect.

Nonalcoholic fatty liver disease impairs the cytochrome P-450-dependent metabolism of α-tocopherol (vitamin E)

This study aims to investigate in in vivo and in vitro models of nonalcoholic fatty liver disease (NAFLD) the enzymatic metabolism of α-tocopherol (vitamin E) and its relationship to vitamin E-responsive genes with key role in the lipid metabolism and detoxification of the liver. The experimental models included mice fed a high-fat diet combined or not with fructose (HFD+F) and HepG2 human hepatocarcinoma cells treated with the lipogenic agents palmitate, oleate or fructose. CYP4F2 protein, a cytochrome P-450 isoform with proposed α-tocopherol ω-hydroxylase activity, decreased in HFD and even more in HFD+F mice liver; this finding was associated with increased hepatic levels of α-tocopherol and decreased formation of the corresponding long-chain metabolites α-13-hydroxy and α-13-carboxy chromanols. A decreased expression was also observed for PPAR-γ and SREBP-1 proteins, two vitamin E-responsive genes with key role in lipid metabolism and CYP4F2 gene regulation. A transient activation of CYP4F2 gene followed by a repression response was observed in HepG2 cells during the exposure to increasing levels of the lipogenic and cytotoxic agent palmitic acid; such gene repression effect was further exacerbated by the co-treatment with oleic acid and α-tocopherol and was also observed for PPAR-γ and the SREBP isoforms 1 and 2. Such gene response was associated with increased uptake and ω-hydroxylation of α-tocopherol, which suggests a minor role of CYP4F2 in the enzymatic metabolism of vitamin E in HepG2 cells. In conclusion, the liver metabolism and gene response of α-tocopherol are impaired in experimental NAFLD.

The therapeutic landscape of non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is characterized by lobular inflammation and hepatocellular ballooning, and may be associated with liver fibrosis leading to cirrhosis and its complications. A pharmacological approach is necessary to treat NASH because of failure to change dietary habits and lifestyle in most patients. Insulin resistance with an increased release of free fatty acids, oxidative stress and activation of inflammatory cytokines seem to be key features for disease progression. Thiazolidinediones, such as pioglitazone and antioxidant agents, such as vitamin E, were the first pharmacological options to be evaluated for NASH. In recent years, several new molecules that target different pathways related to NASH pathogenesis, such as liver metabolic homeostasis, inflammation, oxidative stress and fibrosis, have been developed. Obeticholic acid (INT-747) and elafibranor (GFT-505) have provided promising results in phase IIb, randomized, placebo-controlled clinical trials and they are being evaluated in ongoing phase III studies. Most of the potential treatments for NASH are under investigation in phase II studies, with some at phase I. This diversity in possible treatments calls for a better understanding of NASH in order to enrich trial populations with patients more susceptible to progress and to respond. This manuscript aims to review the pharmacological NASH treatment landscape.

A Case of Ataxia with Isolated Vitamin E Deficiency Initially Diagnosed as Friedreich's Ataxia

Ataxia with isolated vitamin E deficiency (AVED) is a rare autosomal recessive condition that is caused by a mutation in the alpha tocopherol transfer protein gene. It is almost indistinguishable clinically from Friedreich's ataxia but with appropriate treatment its devastating neurological features can be prevented. Patients can present with a progressive cerebellar ataxia, pyramidal spasticity, and evidence of a neuropathy with absent deep tendon reflexes. It is important to screen for this condition on initial evaluation of a young patient presenting with progressive ataxia and it should be considered in patients with a long standing ataxia without any diagnosis in view of the potential therapeutics and genetic counselling. In this case report we present a patient who was initially diagnosed with Friedreich's ataxia but was later found to have AVED.

Molecular basis of alcoholic fatty liver disease: From incidence to treatment

Alcoholic liver diseases have complex and multiple pathogenic mechanisms but still no effective treatment. Steatosis or alcoholic fatty liver disease (AFLD) has a widespread incidence and is the first step in the progression to more severe stages of alcoholic liver disease, with concomitant increases in morbidity and mortality rates. The ways in which this progression occurs and why some individuals are susceptible are still unanswered scientific questions. Research with animal models and clinical evidence have shown that it is a multifactorial disease that involves interactions between lipid metabolism, inflammation, the immune response and oxidative stress. Each of these pathways provides a better understanding of the pathogenesis of AFLD and contributes to the development of therapeutic strategies. This review emphasizes the importance of research on alcoholic steatosis based on incidence data, key pathogenic mechanisms and therapeutic interventions, and discusses perspectives on the progression of this disease.

Oxidative stress influence on renal dysfunction in patients with obstructive jaundice: A case and control prospective study

Background: Obstructive Jaundice (OJ) is associated with a significant risk of developing acute renal failure (ARF). The involvement of oxidative stress in the development of cholestasis has been demonstrated in different experimental models. However, its role in the morbidity of human cholestasis is far to be elucidated. The aim of the study was the evaluation of oxidative stress markers in blood from patients with OJ and its relation to complications and benign/malignant evolution of cholestasis. Methods: A prospective cross-sectional study of 105 patients with OJ and 34 control subjects were included. Several markers of liver function and oxidative stress, such as lipoperoxides (LPO), as well as reduced glutathione (GSH), catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were assessed. Results: The patients with OJ showed a marked increase in plasma levels of LPO, SOD and GSH, while GSH-Px levels were decreased. The increase in lipid peroxidation products and the depletion of SOD activity in blood were also related to renal dysfunction. The highest level of LPO was associated with malignant etiology of the disease. The logistic regression analysis showed that the age of the patient and the levels of LPO in blood were predictors of renal dysfunction in OJ patients. Conclusions: This study demonstrates a correlation between oxidative stress and renal dysfunction patients with OJ.

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Obstructive jaundice was associated to a decreased glomerular filtration rate.

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Renal impairment was more frequent in jaundiced patients than in healthy subjects.

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LPO levels were higher in jaundiced patients than in healhy subjects, with highest levels related to malignant ethiology.

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Renal function was affected by the intensity of the biliary obstruction, and the balance between LPO and antioxidant defenses

Inhibition of Human Hepatic Bile Acid Transporters by Tolvaptan and Metabolites: Contributing Factors to Drug-Induced Liver Injury?

Tolvaptan is a vasopressin V(2)-receptor antagonist that has shown promise in treating Autosomal Dominant Polycystic Kidney Disease (ADPKD). Tolvaptan was, however, associated with liver injury in some ADPKD patients. Inhibition of bile acid transporters may be contributing factors to drug-induced liver injury. In this study, the ability of tolvaptan and two metabolites, DM-4103 and DM-4107, to inhibit human hepatic transporters (NTCP, BSEP, MRP2, MRP3, and MRP4) and bile acid transport in sandwich-cultured human hepatocytes (SCHH) was explored. IC(50) values were determined for tolvaptan, DM-4103 and DM-4107 inhibition of NTCP (∼41.5, 16.3, and 95.6 μM, respectively), BSEP (31.6, 4.15, and 119 μM, respectively), MRP2 (>50, ∼51.0, and >200 μM, respectively), MRP3 (>50, ∼44.6, and 61.2 μM, respectively), and MRP4 (>50, 4.26, and 37.9 μM, respectively). At the therapeutic dose of tolvaptan (90 mg), DM-4103 exhibited a C(max)/IC(50) value >0.1 for NTCP, BSEP, MRP2, MRP3, and MRP4. Tolvaptan accumulation in SCHH was extensive and not sodium-dependent; intracellular concentrations were ∼500 μM after a 10-min incubation duration with tolvaptan (15 μM). The biliary clearance of taurocholic acid (TCA) decreased by 43% when SCHH were co-incubated with tolvaptan (15 μM) and TCA (2.5 μM). When tolvaptan (15 μM) was co-incubated with 2.5 μM of chenodeoxycholic acid, taurochenodeoxycholic acid, or glycochenodeoxycholic acid in separate studies, the cellular accumulation of these bile acids increased by 1.30-, 1.68-, and 2.16-fold, respectively. Based on these data, inhibition of hepatic bile acid transport may be one of the biological mechanisms underlying tolvaptan-associated liver injury in patients with ADPKD.

Chenodeoxycholic acid increases the induction of CYP1A1 in HepG2 and H4IIE cells

Bile acids are considered to promote carcinogenesis. Cytochrome P450 1A1 (CYP1A1) plays a critical role in the biotransformation of drugs and procarcinogens. This study aimed to investigate the ability of bile acids to modulate CYP1A1 expression. Treatment of HepG2 cells with chenodeoxycholic acid (CDCA) and Sudan III (S.III) upregulated CYP1A1 transcriptional activity in HepG2 cells and CYP1A1 mRNA expression in H4IIE cells. Pretreatment of the HepG2 and H4IIE cells with CDCA upregulated the S.III-induced CYP1A transcriptional activity and mRNA expression. The CDCA-induced enhancement of CYP1A1 was not abolished by the p38 inhibitor SB203580. However, exposure of the cells to the mitogen-activated protein kinase kinase (MEK)1/2 inhibitor PD98059 suppressed the CDCA-induced enhancement of CYP1A1. These results show the ability of CDCA to upregulate CYP1A1 transcription and expression, which may explain the hepatocarcinogenesis-inducing effect of cholestasis. The CDCA-induced upregulation of CYP1A1 most probably proceeded through MEK1/2 activation, indicating that this may be a therapeutic target to prevent the cancer-promoting effects of excessive amounts of bile acids.

Nonalcoholic fatty liver disease: new treatments

PURPOSE OF REVIEW

Nonalcoholic fatty liver disease is the most common cause of liver dysfunction in the western world because of its close association with obesity, insulin resistance and dyslipidaemia. Nonalcoholic steatohepatitis (NASH) is a particular health concern due to the increased morbidity and mortality associated with progressive disease. At present, without specific targeted pharmacological therapies, the mainstay of therapy remains weight loss through dietary modification and lifestyle change; thus, the purpose of this review is to summarize the recent evidence for current and emerging therapies in NASH.

RECENT FINDINGS

Some existing medications, including pioglitazones and angiotensin receptor antagonists, may be repurposed to help treat this condition. Vitamin E may improve histology in NASH, but safety issues limit its use. Recently, a number of novel agents specifically targeting nonalcoholic fatty liver disease pathogenesis have entered clinical trials, including the farnesoid X receptor agonist obeticholic acid, which has shown significant histological improvements in steatohepatitis and fibrosis.

SUMMARY

Diet/lifestyle modification remains the mainstay of treatment. For patients with NASH and advanced fibrosis, current liver-directed pharmacotherapy with vitamin E and pioglitazone offer some benefits; obeticholic acid appears promising and is currently being tested. Comorbidities must be diagnosed and treated; cardiovascular disease remains a primary cause of death in these patients.

Current efforts and trends in the treatment of NASH

Of all the aspects of non-alcoholic fatty liver disease (NAFLD), the slowest advances have occurred in the therapeutic field. Thirty-five years after its formal description and after 15 years of intense scrutiny from researchers worldwide, there is still no approved drug for the treatment of non-alcoholic steatohepatits (NASH). In the meantime, progress in the understanding of pathophysiology, diagnosis - both invasive and non-invasive, epidemiology and even natural history have been substantial or, at times, spectacular. In contrast, hepatitis C virus (HCV) therapy underwent constant improvement and even before the great acceleration of the past few years, patients were already being offered approved therapies that were increasingly more efficient. What then explains such a slow pace of therapeutic advances in NASH, and will this change in the near future? Here we will review commonly-held myths that have diverted attention from therapy of NASH, obstacles that have slowed down industrial development of drugs for this indication, and recent achievements that will create better conditions for drug development programs. We will also briefly review current knowledge of non-pharmacological and pharmacological management in this early era of NASH therapies.

Delivery aspects of antioxidants in diabetes management

INTRODUCTION

Ample research has been done to study the role of oxidative stress due to the generation of excess reactive species in initiation and progression of diabetic complications. A positive result has been indicated hypothesizing that abating this oxidative stress can prove to be an alternate strategy in therapy apart from oral antidiabetic drugs. But these dietary antioxidants are less efficient because of poor solubility, permeability, instability on storage, gastrointestinal degradation and first-pass metabolism.

AREAS COVERED

This review gives a brief insight into the molecular mechanism of oxidative stress in development of diabetic complications. Major hurdles limiting the translation of antioxidants to clinical area are also discussed. Various delivery approaches including both conventional and novel drug delivery systems explored so far for combating these challenges in antioxidant delivery are also explored. Mitochondrial targeting of such molecules is also briefly discussed.

EXPERT OPINION

A thorough study of clinical efficacy and safety of antioxidants on long-term use judging its clinical applicability is required. The clinical success of antioxidants as a therapeutic strategy involves a combination of effective design of drug delivery carrier that are in turn related to their degradation profile, possibility of cellular uptake at defined site of action and so on and clinical and preclinical trials that will provide a base for the design of dose and administration regimen.

Branched-Chain Amino Acid-Rich Supplements Containing Microelements Have Antioxidant Effects on Nonalcoholic Steatohepatitis in Mice

BACKGROUND

The aim of the present study was to elucidate whether the administration of antioxidant-rich nutrients, including branched-chain amino acids (BCAAs), microelements, and vitamins, both alone and in combination, has a positive impact on liver function in a nonalcoholic steatohepatitis (NASH) mouse model and identify the mechanisms underlying these effects.

METHODS

Seven-week-old male KKAy mice fed a methionine- and choline-deficient diet (MCD) for 4 weeks were divided into 7 groups and fed the following planned diets for another 4 weeks: group A (normal diet), group B (MCD; control), group C (MCD with rich microelements), group D (MCD with rich BCAAs), group E (MCD with rich microelements and BCAAs), and group F (MCD with rich microelements, BCAAs, and vitamins). We then conducted biochemical assays, histological analyses, immunohistochemistry for 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 4-hydroxy-2'-nonenal (4-HNE), and Western blotting for insulin glucose signaling, lipid metabolism, and endoplasmic reticulum (ER) stress-related signaling in liver specimens obtained from mice in each group.

RESULTS

The morphometric grades of all NASH-related findings and the mean degree of 8-OHdG immunolocalization in groups D-F were significantly lower than those observed in group B. The expression levels of insulin receptor β subunit (IRβ) and p-elF in groups E and F and those of phosphatidyl-inositol 3 kinase (PI3K85), p-AcelCoA, and PERK in group F were similar to those noted in group A.

CONCLUSIONS

The administration of a combination of antioxidant-rich nutrients, including BCAAs and microelements, is likely to suppress the progression of NASH by reducing oxidative stress, primarily via the downregulation of the ER stress pathway.

L-carnitine prevents progression of non-alcoholic steatohepatitis in a mouse model with upregulation of mitochondrial pathway

Non-alcoholic steatohepatitis (NASH) is a severe form of non-alcoholic fatty liver disease characterized by lobular inflammation, hepatocellular ballooning, and fibrosis with an inherent risk for progression to cirrhosis and hepatocellular carcinoma (HCC). Mitochondrial dysfunction appears to play a role in the progression from simple steatosis to NASH. L-carnitine (L-b-hydroxy-g-N-trimethylaminobutyric acid), an essential nutrient that converts fat into energy in mitochondria, has been shown to ameliorate liver damage. The aim of the present study was to explore the preventive and therapeutic effect of L-carnitine in NASH model mice. Eight-week-old male STAM mice, a NASH-cirrhosis-hepatocarcinogenic model, were divided into 3 experimental groups and fed as follows: 1) high-fat diet (HFD) (control group); 2) HFD mixed with 0.28% L-carnitine (L-carnitine group); and 3) HFD mixed with 0.01% α-tocopherol (α-tocopherol group). After 4 or 8 weeks, mice were sacrificed. Blood samples and livers were collected, and hepatic tumors were counted and measured. Livers were subjected to histological study, immunohistochemical staining of 4-hydroxynonenal and ferritin, determination of 8-OHdG levels, mRNA and protein expressions for multiple genes, and metabolomic analysis. The intestinal microbiome was also analyzed. L-carnitine increased hepatic expression of genes related to long-chain fatty acid transport, mitochondrial β-oxidation, and antioxidant enzymes following suppression of hepatic oxidative stress markers and inflammatory cytokines in NASH, and mice treated with L-carnitine developed fewer liver tumors. Although α-tocopherol resulted in NASH improvement in the same manner as L-carnitine, it increased periodontitis-related microbiotic changes and hepatic iron transport-related gene expression and led to less effective for anti-hepatocarcinogenesis.

Conclusion

L-carnitine prevents progression of non-alcoholic steatohepatitis in a mouse model by upregulating the mitochondrial β-oxidation and redox system.

Choline supplementation protects against liver damage by normalizing cholesterol metabolism in Pemt/Ldlr knockout mice fed a high-fat diet

Dietary choline is required for proper structure and dynamics of cell membranes, lipoprotein synthesis, and methyl-group metabolism. In mammals, choline is synthesized via phosphatidylethanolamine N-methyltransferase (Pemt), which converts phosphatidylethanolamine to phosphatidylcholine. Pemt(-/-) mice have impaired VLDL secretion and developed fatty liver when fed a high-fat (HF) diet. Because of the reduction in plasma lipids, Pemt(-/-)/low-density lipoprotein receptor knockout (Ldlr(-/-)) mice are protected from atherosclerosis. The goal of this study was to investigate the importance of dietary choline in the metabolic phenotype of Pemt(-/-)/Ldlr(-/-) male mice. At 10-12 wk of age, Pemt(+/+)/Ldlr(-/-) (HF(+/+)) and half of the Pemt(-/-)/Ldlr(-/-) (HF(-/-)) mice were fed an HF diet with normal (1.3 g/kg) choline. The remaining Pemt(-/-)/Ldlr(-/-) mice were fed an HF diet supplemented (5 g/kg) with choline (HFCS(-/-) mice). The HF diet contained 60% of calories from fat and 1% cholesterol, and the mice were fed for 16 d. HF(-/-) mice lost weight and developed hepatomegaly, steatohepatitis, and liver damage. Hepatic concentrations of free cholesterol, cholesterol-esters, and triglyceride (TG) were elevated by 30%, 1.1-fold and 3.1-fold, respectively, in HF(-/-) compared with HF(+/+) mice. Choline supplementation normalized hepatic cholesterol, but not TG, and dramatically improved liver function. The expression of genes involved in cholesterol transport and esterification increased by 50% to 5.6-fold in HF(-/-) mice when compared with HF(+/+) mice. Markers of macrophages, oxidative stress, and fibrosis were elevated in the HF(-/-) mice. Choline supplementation normalized the expression of these genes. In conclusion, HF(-/-) mice develop liver failure associated with altered cholesterol metabolism when fed an HF/normal choline diet. Choline supplementation normalized cholesterol metabolism, which was sufficient to prevent nonalcoholic steatohepatitis development and improve liver function. Our data suggest that choline can promote liver health by maintaining cholesterol homeostasis.

Pharmacological agents for NASH

NASH is a common liver disease that increases liver-related mortality and reduces survival. The need for optimal management of NASH is therefore a priority for today's practicing hepatologist. The rationale for specific pharmacological therapy for NASH is based on the potential for disease progression and the difficulties that many patients have successfully implementing, in the long term, diet and lifestyle changes. Even in those that succeed, limited evidence exists that severe liver injury in patients with NASH can be reversed by diet and lifestyle measures alone. This Review provides a personal and critical assessment of the histological efficacy and safety of agents tested in randomized trials in patients with NASH.

Targeting mitochondrial reactive oxygen species as novel therapy for inflammatory diseases and cancers

There are multiple sources of reactive oxygen species (ROS) in the cell. As a major site of ROS production, mitochondria have drawn considerable interest because it was recently discovered that mitochondrial ROS (mtROS) directly stimulate the production of proinflammatory cytokines and pathological conditions as diverse as malignancies, autoimmune diseases, and cardiovascular diseases all share common phenotype of increased mtROS production above basal levels. Several excellent reviews on this topic have been published, but ever-changing new discoveries mandated a more up-to-date and comprehensive review on this topic. Therefore, we update recent understanding of how mitochondria generate and regulate the production of mtROS and the function of mtROS both in physiological and pathological conditions. In addition, we describe newly developed methods to probe or scavenge mtROS and compare these methods in detail. Thorough understanding of this topic and the application of mtROS-targeting drugs in the research is significant towards development of better therapies to combat inflammatory diseases and inflammatory malignancies.

Antioxidant therapy in nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) affects up to 3% of the North American population. It occurs as a manifestation of the insulin-resistant state and oxidative stress is thought to be a key component of its pathophysiology. Exercise and diet, which are the mainstay of therapy, are difficult to achieve and maintain with a disappointing long-term compliance record. There is growing literature on the potential for antioxidant therapy. The recent literature strongly suggests that vitamin E supplementation and other putative free radical scavengers and/or antioxidants are beneficial in improving biochemical and histological parameters in NASH.

The effect of ursodeoxycholic acid on oxidative stress level and DNase activity in rat liver after bile duct ligation

Accumulation of hydrophobic bile acids (BAs) during cholestasis plays an important role in apoptosis initiation as well as oxidative stress increase in liver cells. Ursodeoxycholic acid (UDCA) acts as a protector in BA-induced cell injury.The aim of the study was to evaluate the effect of UDCA on oxidative stress level and DNase I and II activity caused by liver injury in bile duct ligation (BDL) rats.Wistar rats were divided in four groups: group 1, control (sham-operated); group 2, sham-operated and injected with UDCA (30 mg/kg); group 3,animals with BDL; and group 4,UDCA-treatedcholestatic rats. Animals were sacrificed after 9 days. Malondialdehyde (MDA; lipid peroxidation end-product) level and protein-molecule oxidative modification (carbonyl group content) significantly increased in BDL rat liver. Catalase (CAT) activity in liver tissue was found to be decreased in BDL rats. In addition, xanthine oxidase (XO) activity, which is thought to be one of the key enzymes producing reactive oxygen species, was found to be increased in the cholestatic group. The apoptotic effect in cholestasis was probably triggered by the increased activation of DNase I and II. The protective effect of UDCA on liver tissue damage in BDL rats, in comparison to cholestatic liver, were 1) decrease of MDA levels, 2) increased CAT activity, 3) reduced XO activity, and 4) effect on terminal apoptotic reaction, shown as a decrease in DNase I and II activity.Therefore, UDCA may be useful in the preservation of liver function in cholestasis treatment.

Subacute bilateral visual loss in methylmalonic acidemia

A 23-year-old woman known to have methylmalonic acidemia (MMA) since birth suffered bilateral visual loss within 5 days. Multiple sclerosis, Leber hereditary optic neuropathy, vasculitis, infections (in particular treponema), and vitamin deficiency were ruled out. The optic nerve head changed from normal in appearance to atrophic. Treatment attempts with high-dose intravenous steroids and coenzyme Q10 combined with vitamin E were ineffective. The patient's underlying disease was metabolically well controlled by strict diet and carnitine supplementation. Toxic damage of both optic nerves due to MMA is the most likely mechanism. MRI showed moderate enhancement of both optic nerves. To our knowledge, this is the first report of a morphological correlate on MRI.

Tumor spectrum in lynch syndrome, DNA mismatch repair system and endogenous carcinogens

Inactivation of Mismatch Repair genes in Lynch Syndrome, caused by inherited mutations, decreases the ability to repair DNA errors throughout life. This deficit may allow the development of any tumor type. Nevertheless, the Syndrome develops a specific tumor spectrum associated with the disease. We think that such spectrum of tumors would be related to the action of certain endogenous carcinogens such as bile acids and estrogens that aggravate the inherited defect.

Trolox mitigates fibrosis in a bile duct ligation model

Several studies suggest that free radicals may play a role in cholestatic liver injury. The aim of this work was to evaluate the role of trolox in chronic bile duct ligation (BDL). Liver injury was induced by 28-day BDL to male Wistar rats. Animals were divided in four groups of six rats. Trolox was administered daily (50 mg/kg, p.o.). Alanine aminotransferase (ALT) was quantified in serum. Fibrosis was assessed measuring liver hydroxyproline content. Reduced (GSH) and oxidized (GSSG) glutathione, lipid peroxidation, catalase (CAT), and glutathione peroxidase (GPx) activities were measured in liver. Transforming growth factor-β (TGF-β), interleukin-6 (IL-6), and interleukin-10 (IL-10) were determined by western blot and quantified densitometrically. Our results show that trolox treatment in BDL rats prevented the increase in ALT. Collagen was increased by chronic BDL, but trolox administration preserved the normal collagen concentration. BDL produced high levels of the cytokine TGF-β1, IL-6, and IL-10 levels. Trolox administration was effective to partially prevent the increase of TGF-β1 and IL-6, and it was able to further augment the levels of IL-10. Oxidative stress (assessed by lipid peroxidation and liver glutathione content) was increased by BDL; this process was normalized by trolox. The activities of CAT and GPx were altered by BDL, and trolox prevented these events. We found that there is a close relationship between cholestatic liver damage and oxidative stress generation, and this was effectively prevented by trolox. Our study shows that the beneficial effects of trolox are because of its important antioxidant and immunomodulatory properties.

Cytoprotective properties of rifampicin are related to the regulation of detoxification system and bile acid transporter expression during hepatocellular injury induced by hydrophobic bile acids

BACKGROUND/PURPOSE

Rifampicin has been used for the treatment of patients with jaundice and pruritus. This study evaluated the effect of rifampicin on the expression of different detoxification systems and bile acid transporters during in-vivo and in-vitro experimental models of cholestasis.

METHODS

Rifampicin was administered to glycochenodeoxycholic acid (GCDCA)-treated human hepatocytes and bile duct-obstructed rats. Different parameters related to cell death, and the expression of phase I and II drug metabolizing enzymes (DME) and bile acid transporters were determined.

RESULTS

The induction of hepatocellular injury induced by cholestasis was associated with a reduction in cytochrome P4503A4 (CYP3A4), CYP7A1, and UDP-glucuronosyltransferase 2B4 (UGT2B4) expression, as well as an increase in import (Na(+)-taurocholate co-transporting polypeptide, NTCP) system expression. The beneficial properties of rifampicin were associated with an increase in DME and export bile acid systems (multidrug resistance-associated protein 4, MRP4, and bile acid export pump to bile duct, BSEP) expression, as well as a reduction in NTCP expression.

CONCLUSIONS

The beneficial effect of rifampicin in cholestasis is associated with an increase in DME expression involved in toxic, bile acid and cholesterol metabolism, as well as a reduction in the bile acid importing system in hepatocytes.

Ursodeoxycholic acid in cholestasis: linking action mechanisms to therapeutic applications

UDCA (ursodeoxycholic acid) is the therapeutic agent most widely used for the treatment of cholestatic hepatopathies. Its use has expanded to other kinds of hepatic diseases, and even to extrahepatic ones. Such versatility is the result of its multiple mechanisms of action. UDCA stabilizes plasma membranes against cytolysis by tensioactive bile acids accumulated in cholestasis. UDCA also halts apoptosis by preventing the formation of mitochondrial pores, membrane recruitment of death receptors and endoplasmic-reticulum stress. In addition, UDCA induces changes in the expression of metabolizing enzymes and transporters that reduce bile acid cytotoxicity and improve renal excretion. Its capability to positively modulate ductular bile flow helps to preserve the integrity of bile ducts. UDCA also prevents the endocytic internalization of canalicular transporters, a common feature in cholestasis. Finally, UDCA has immunomodulatory properties that limit the exacerbated immunological response occurring in autoimmune cholestatic diseases by counteracting the overexpression of MHC antigens and perhaps by limiting the production of cytokines by immunocompetent cells. Owing to this multi-functionality, it is difficult to envisage a substitute for UDCA that combines as many hepatoprotective effects with such efficacy. We predict a long-lasting use of UDCA as the therapeutic agent of choice in cholestasis.

Redox balance in the pathogenesis of nonalcoholic fatty liver disease: mechanisms and therapeutic opportunities

Nonalcoholic fatty liver disease (NAFLD) is currently the most common liver disease in the world. It encompasses a histological spectrum, ranging from simple, nonprogressive steatosis to nonalcoholic steatohepatitis (NASH), which may progress to cirrhosis and hepatocellular carcinoma. While liver-related complications are confined to NASH, emerging evidence suggests both simple steatosis and NASH predispose to type 2 diabetes and cardiovascular disease. The pathogenesis of NAFLD is currently unknown, but accumulating data suggest that oxidative stress and altered redox balance play a crucial role in the pathogenesis of steatosis, steatohepatitis, and fibrosis. We will examine intracellular mechanisms, including mitochondrial dysfunction and impaired oxidative free fatty acid metabolism, leading to reactive oxygen species generation; additionally, the potential pathogenetic role of extracellular sources of reactive oxygen species in NAFLD, including increased myeloperoxidase activity and oxidized low density lipoprotein accumulation, will be reviewed. We will discuss how these mechanisms converge to determine the whole pathophysiological spectrum of NAFLD, including hepatocyte triglyceride accumulation, hepatocyte apoptosis, hepatic inflammation, hepatic stellate cell activation, and fibrogenesis. Finally, available animal and human data on treatment opportunities with older and newer antioxidant will be presented.

Nitric oxide mimics transcriptional and post-translational regulation during α-tocopherol cytoprotection against glycochenodeoxycholate-induced cell death in hepatocytes

BACKGROUND & AIMS

Reactive oxygen species (ROS) and nitric oxide (NO) exert a relevant role during bile acid-induced hepatotoxicity. Whether α-Tocopherol regulates oxidative and nitrosative stress, bile acid transporter expression and their NO-dependent post-translational modifications, and cell death were assessed in vitro and in vivo.

METHODS

α-Tocopherol and/or NO donors (DETA-NONOate or CSNO, and V-PYRRO/NO) were administered to glycochenodeoxycholic acid (GCDCA)-treated cultured human hepatocytes or to bile duct obstructed rats. Cell injury, superoxide anion (O⁻₂) production, as well as inducible nitric oxide synthase (NOS-2), cytochrome P4507A1 (CYP7A1), heme oxygenase-1, (HO-1) and bile acid transporter expression were determined. Cysteine S-nitrosylation and tyrosine nitration of Na(+)-taurocholate co-transporting polypeptide (NTCP), as well as taurocholic acid (TC) uptake were also evaluated.

RESULTS

GCDCA-induced cell death was associated with increased (O⁻₂) production, NTCP and HO-1 expression, and with a reduction of CYP7A1 and NOS-2 expression. α-Tocopherol reduced cell death, (O⁻₂) production, CYP7A1, NTCP, and HO-1 expression, as well as increased NOS-2 expression and NO production in GCDCA-treated hepatocytes. α-Tocopherol and NO donors increased NTCP cysteine S-nitrosylation and tyrosine nitration, and reduced TC uptake in hepatocytes. α-Tocopherol and V-PYRRO/NO reduced liver injury and NTCP expression in obstructed rats.

CONCLUSIONS

The regulation of CYP7A1, NTCP, and HO-1 expression may be relevant for the cytoprotective properties of α-Tocopherol and NO against mitochondrial dysfunction, oxidative stress and cell death in GCDCA-treated hepatocytes. The regulation of NO-dependent post-translational modifications of NTCP by α-Tocopherol and NO donors reduces the uptake of toxic bile acids by hepatocytes.

Effect of a mitochondria-targeted vitamin E derivative on mitochondrial alteration and systemic oxidative stress in mice

The objective of the present study was to determine whether a mitochondria-targeted vitamin E derivative (MitoVit E) would affect certain mitochondrial parameters, as well as systemic oxidative stress. A total of sixty-four mice were fed a high-fat (HF) diet for 5 weeks. They were then switched to either a low-fat (LF) or a medium-fat (MF) diet, and administered orally with MitoVit E (40 mg MitoVit E/kg body weight) or drug vehicle (10 % (v/v) ethanol in 0·9 % (w/v) NaCl solution), every other day for 5 weeks. Mitochondrial ATP and H(2)O(2) production rates in both the liver and the gastrocnemius were not affected by MitoVit E administration in either LF or MF diet-fed mice. However, the number and average size of the subsarcolemmal mitochondria, but not the intermyofibrillar mitochondria, from the soleus muscle were significantly higher in the MF group receiving MitoVit E (MF-E) than in the MF group receiving vehicle only (MF-C). After the mice were switched from the HF diet to the four dietary treatments (LF-C, LF-E, MF-C and MF-E), the decrease in urinary isoprostane concentration was significantly greater in the LF-E group than in the other three groups during the whole study (weeks 6-10). In addition, MitoVit E significantly increased plasma superoxide dismutase (SOD) activity in the MF diet-fed group without affecting plasma glutathione peroxidase activity or H(2)O(2) levels. Overall, these data suggest that MitoVit E affects subsarcolemmal mitochondrial density and systemic oxidative stress parameters such as plasma SOD activity and urinary isoprostane concentration.