Enhanced intrahepatic inducible nitric oxide synthase expression and nitrotyrosine accumulation in primary biliary cirrhosis and autoimmune hepatitis

The role of amino acid metabolism in autoimmune hepatitis

Autoimmune hepatitis (AIH) is an inflammatory chronic liver disease with persistent and recurrent immune-mediated liver injury. The exact cause of AIH is still not fully understood, but it is believed to be primarily due to an abnormal activation of the immune system, leading to autoimmune injury caused by the breakdown of autoimmune tolerance. Although the pathogenesis of AIH remains unclear, recent studies have shown that abnormalities in amino acid metabolism play significant roles in its development. These abnormalities in amino acid metabolism can lead to remodeling of metabolic processes, activation of signaling pathways, and immune responses, which may present new opportunities for clinical intervention in AIH. In this paper, we first briefly outline the recent progress of clinically relevant research on AIH, focusing on the role of specific amino acid metabolism (including glutamine, cysteine, tryptophan, branched-chain amino acids, etc.) and their associated metabolites, as well as related pathways, in the development of AIH. Furthermore, we discuss the scientific issues that remain to be resolved regarding amino acid metabolism, AIH development and related clinical interventions, with the aim of contributing to the future development of amino acid metabolism-based as a new target for the clinical diagnosis and treatment of AIH.

Sophoricoside attenuates autoimmune‑mediated liver injury through the regulation of oxidative stress and the NF‑κB signaling pathway

The prevalence of autoimmune hepatitis (AIH) is increasing, yet specific pharmacotherapies remain to be explored. The present study aimed to investigate the effects of sophoricoside (SOP), a bioactive component of medical herbs, on AIH and to elucidate the underlying mechanisms. Bioinformatic approaches were used to predict the potential targets and underlying regulatory mechanisms of SOP on AIH. The effects of SOP on AIH were evaluated by determining the expression levels of inflammatory cytokines, histological liver injury and hepatic fibrosis in an improved chronic cytochrome P450 2D6 (CYP2D6)‑AIH mouse model and in a model of concanavalin‑A (ConA)‑induced acute immune‑mediated liver injury. The antioxidant activity of SOP was detected in in vivo and in vitro experiments. The selected signal targeted by SOP in AIH was further confirmed using western blot analysis and immunofluorescence staining. The results of bioinformatic analysis revealed that the targets of SOP in AIH were related to oxidative stress and the NF‑κB gene set. The NF‑κB transcription factor family is a key player that controls both innate and adaptive immunity. The activation of the NF‑κB signaling pathway is often associated with autoimmune disorders. In the animal experiments, SOP attenuated CYP2D6/ConA‑induced AIH, as evidenced by a significant reduction in the levels of hepatic enzymes in serum, inflammatory cytokine expression and histological lesions in the liver. The oxidative response in AIH was also significantly inhibited by SOP, as evidenced by a decrease in the levels of hepatic malondialdehyde, and elevations in the total antioxidant capacity and glutathione peroxidase levels. The results of the in vivo and in vitro experiments revealed that SOP significantly reduced the enhanced expression and nuclear translocation of phosphorylated p65 NF‑κB in the livers of mice with AIH and in lipopolysaccharide‑stimulated AML12 cells. On the whole, the present study demonstrates the protective role of SOP in AIH, which may be mediated by limiting the oxidative response and the activation of the NF‑κB signaling pathway in hepatocytes.

Insight into increased risk of portal vein thrombosis in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is one of the leading chronic liver diseases with increased morbidity and mortality rates for extrahepatic diseases (including cardiovascular disease, portal vein thrombosis, etc.). There is an increased risk of thrombosis in both the portal and systemic circulation in patients with NAFLD, independent of traditional liver cirrhosis. However, increased portal pressure, the most critical factor, is frequently observed in NAFLD patients, predisposing them to portal vein thrombosis (PVT). It has been reported that there is an 8.5% incidence of PVT among patients with non-cirrhotic NAFLD in a prospective cohort study. Based on the prothrombotic status of NAFLD itself, patients combined with cirrhosis may accelerate the development of PVT and lead to a poor prognosis. Moreover, PVT has been shown to complicate the procedure and adversely affect the outcome during liver transplantation surgery. NAFLD is in a prothrombotic state, and its underlying mechanisms have not been fully understood so far. Particularly noteworthy is that gastroenterologists currently overlook the higher risk of PVT in NAFLD. We investigate the pathogenesis of NAFLD complicated with PVT from the perspective of primary, secondary, and tertiary hemostasis, and also summarize relevant studies in humans. Some treatment options that may affect NAFLD and its PVT are also explored to improve patient-oriented outcomes.

Dietary gluten worsens hepatic steatosis by increasing inflammation and oxidative stress in ApoE-/- mice fed a high-fat diet

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disorder in the world. We have seen that gluten intake exacerbated obesity and atherosclerosis in apolipoprotein E knockout (ApoE-/-) mice. In this study, we investigated the effect of gluten consumption on inflammation and oxidative stress in the liver of mice with NAFLD. Male ApoE-/- mice were fed a gluten-free (GF-HFD) or gluten-containing (G-HFD) high-fat diet for 10 weeks. Blood, liver, and spleen were collected to perform the analyses. The animals of the gluten group had increased hepatic steatosis, followed by increased serum AST and ALT. Gluten intake increased hepatic infiltration of neutrophils, macrophages, and eosinophils, as well as the levels of chemotaxis-related factors CCL2, Cxcl2, and Cxcr3. The production of the TNF, IL-1β, IFNγ, and IL-4 cytokines in the liver was also increased by gluten intake. Furthermore, gluten exacerbated the hepatic lipid peroxidation and nitrotyrosine deposition, which were associated with increased production of ROS and nitric oxide. These effects were related to increased expression of NADPH oxidase and iNOS, as well as decreased activity of superoxide dismutase and catalase enzymes. There was an increased hepatic expression of the NF-κB and AP1 transcription factors, corroborating the worsening effect of gluten on inflammation and oxidative stress. Finally, we found an increased frequency of CD4+FOXP3+ lymphocytes in the spleen and increased gene expression of Foxp3 in the livers of the G-HFD group. In conclusion, dietary gluten aggravates NAFLD, exacerbating hepatic inflammation and oxidative stress in obese ApoE-deficient mice.

Blood Levels of Glutamine and Nitrotyrosine in Patients with Chronic Viral Hepatitis

Purpose

Oxidative stress is involved in pathogenesis of chronic viral hepatitis. Glutamine is an antioxidant, but there is a controversy about its risk-benefits. Nitrotyrosine is an oxidative stress marker. This observational cross-sectional study was designed to compare blood levels of glutamine and nitrotyrosine in treated versus untreated chronic viral hepatitis patients.

Patients and Methods

Five groups (n = 250) were included: hepatitis B untreated (HBV), hepatitis C untreated (HCV), HBV treated (HBVT), and HCV treated (HCVT) groups plus a normal control group. Liver function tests and blood levels of glutamine, nitrotyrosine, viral loads, and HBsAg were measured.

Results

Blood levels of glutamine and nitrotyrosine in all patient groups significantly increased compared with normal controls with non-significant differences in-between. Both tests showed significant large correlations with HBV-DNA or HCV-RNA test positivity, high accuracies, and cutoff scores with high sensitivities and specificities. The viral loads and HBsAg levels were significantly lower in treated versus untreated groups. However, they poorly correlated with levels of glutamine and nitrotyrosine in all patient groups.

Conclusion

Blood levels of glutamine and nitrotyrosine significantly increased in treated and untreated chronic viral hepatitis B and C patients compared with normal controls. Both tests showed high accuracies and cutoff scores with high sensitivities and specificities. However, they did not differ significantly in treated versus untreated patients. To our knowledge, this is the first data showing elevation of glutamine and nitrotyrosine in treated and untreated chronic viral hepatitis. A prospective longitudinal study with repeated measurements of glutamine and nitrotyrosine is recommended to verify if they can predict response to treatment. Study of other oxidative stress markers is also advised to clarify if the elevated nitrotyrosine could be an oxidative stress marker in these patients, and whether the increased glutamine could act as an antioxidant or as a predictive agent for deleterious consequences.

The effect of turmeric on lipid profile, malondialdehyde, liver echogenicity and enzymes among patients with nonalcoholic fatty liver disease: a randomized double blind clinical trial

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is one of the most common causes of liver transaminases elevation and a global health concern.

PURPOSE

This study designed to evaluate the effects of turmeric rhizomes (Curcumalonga Linn.) on liver enzymes, Lipid profiles and Malondialdehyde (MDA) in patients with NAFLD.

STUDY DESIGN

Randomized double-blind placebo controlled trial.

METHODS

64 cases of NAFLD randomly assigned to receive either turmeric (2 gr/day) or placebo for 8 weeks. The changes of liver transaminases, lipid profiles and MDA were measured before and after study period and compared between two groups (IRCT 2015092924262N1).

RESULTS

At the end of the study, the Turmeric group showed a significant reduction in liver enzymes (AST before 26.81 ± 10.54 after 21.19 ± 5.67, P = 0.044, ALT before 39.56 ± 22.41, after 30.51 ± 12.61, P = 0.043 and GGT before33.81 ± 17.50, after 25.62 ± 9.88, P = 0.046) compared with the placebo group. The serum levels of triglycerides, LDL, HDL and MDA had also a significant decrease among turmeric group as compared to baseline while there was no significant change in placebo group (P < 0.05). The serum cholesterol, VLDL level and sonographic grades of NAFLD had not any significant change in both groups.

CONCLUSION

In conclusion this study suggests that daily consumption of turmeric (and its active phenolic ingredients as curcumin) supplementation could be effective in management of NAFLD and decreasing serum level of liver transaminases.

Role of cytoglobin, a novel radical scavenger, in stellate cell activation and hepatic fibrosis

Cytoglobin (Cygb), a stellate cell-specific globin, has recently drawn attention due to its association with liver fibrosis. In the livers of both humans and rodents, Cygb is expressed only in stellate cells and can be utilized as a marker to distinguish stellate cells from hepatic fibroblast-derived myofibroblasts. Loss of Cygb accelerates liver fibrosis and cancer development in mouse models of chronic liver injury including diethylnitrosamine-induced hepatocellular carcinoma, bile duct ligation-induced cholestasis, thioacetamide-induced hepatic fibrosis, and choline-deficient L-amino acid-defined diet-induced non-alcoholic steatohepatitis. This review focuses on the history of research into the role of reactive oxygen species and nitrogen species in liver fibrosis and discusses the current perception of Cygb as a novel radical scavenger with an emphasis on its role in hepatic stellate cell activation and fibrosis.

Evolving Role of Vitamin D in Immune-Mediated Disease and Its Implications in Autoimmune Hepatitis

Vitamin D has immunomodulatory, anti-inflammatory, antioxidant, and anti-fibrotic actions that may impact on the occurrence and outcome of immune-mediated disease. The goals of this review are to describe the nature of these expanded roles, examine the implications of vitamin D deficiency in autoimmune hepatitis, and identify opportunities for future investigation. Abstracts were identified in PubMed by multiple search terms. Full-length articles were selected for review, and secondary and tertiary bibliographies were developed. Vitamin D receptors are expressed on the principal cell populations involved in the innate and adaptive immune responses. Macrophages and dendritic cells can produce 1,25-dihydroxyvitamin D within the microenvironment. This active form of vitamin D can inhibit immune cell proliferation, promote an anti-inflammatory cytokine profile, expand regulatory T cells, enhance glucocorticoid actions, increase glutathione production, and inhibit hepatic stellate cells. Vitamin D deficiency has been commonly present in patients with immune-mediated liver and non-liver diseases, and it has been associated with histological severity, advanced hepatic fibrosis, and non-response to conventional glucocorticoid therapy in autoimmune hepatitis. Vitamin D analogues with high potency, low calcemic effects, and independence from hepatic hydroxylation are possible interventions. In conclusion, vitamin D has properties that could ameliorate immune-mediated disease, and vitamin D deficiency has been a common finding in immune-mediated liver and non-liver diseases, including autoimmune hepatitis. Loss of vitamin D-dependent homeostatic mechanisms may promote disease progression. Vitamin D analogues that are independent of hepatic hydroxylation constitute an investigational opportunity to supplement current management of autoimmune hepatitis.

Under-Evaluated or Unassessed Pathogenic Pathways in Autoimmune Hepatitis and Implications for Future Management

Autoimmune hepatitis is a consequence of perturbations in homeostatic mechanisms that maintain self-tolerance but are incompletely understood. The goals of this review are to describe key pathogenic pathways that have been under-evaluated or unassessed in autoimmune hepatitis, describe insights that may shape future therapies, and encourage investigational efforts. The T cell immunoglobulin mucin proteins constitute a family that modulates immune tolerance by limiting the survival of immune effector cells, clearing apoptotic bodies, and expanding the population of granulocytic myeloid-derived suppressor cells. Galectins influence immune cell migration, activation, proliferation, and survival, and T cell exhaustion can be induced and exploited as a possible management strategy. The programmed cell death-1 protein and its ligands comprise an antigen-independent inhibitory axis that can limit the performance of activated T cells by altering their metabolism, and epigenetic changes can silence pro-inflammatory genes or de-repress anti-inflammatory genes that affect disease severity. Changes in the intestinal microbiota and permeability of the intestinal mucosal barrier can be causative or consequential events that affect the occurrence and phenotype of immune-mediated disease, and they may help explain the female propensity for autoimmune hepatitis. Perturbations within these homeostatic mechanisms have been implicated in experimental models and limited clinical experiences, and they have been favorably manipulated by monoclonal antibodies, recombinant molecules, pharmacological agents or dietary supplements. In conclusion, pathogenic mechanisms that have been implicated in other systemic immune-mediated and liver diseases but under-evaluated or unassessed in autoimmune hepatitis warrant consideration and rigorous evaluation.

Reversal of liver cirrhosis: current evidence and expectations

In the past, liver cirrhosis was considered an irreversible phenomenon. However, many experimental data have provided evidence of the reversibility of liver fibrosis. Moreover, multiple clinical studies have also shown regression of fibrosis and reversal of cirrhosis on repeated biopsy samples. As various etiologies are associated with liver fibrosis via integrated signaling pathways, a comprehensive understanding of the pathobiology of hepatic fibrogenesis is critical for improving clinical outcomes. Hepatic stellate cells play a central role in hepatic fibrogenesis upon their activation from a quiescent state. Collagen and other extracellular material components from activated hepatic stellate cells are deposited on, and damage, the liver parenchyma and vascular structures. Hence, inactivation of hepatic stellate cells can lead to enhancement of fibrolytic activity and could be a potential target of antifibrotic therapy. In this regard, continued efforts have been made to develop better treatments for underlying liver diseases and antifibrotic agents in multiple clinical and therapeutic trials; the best results may be expected with the integration of such evidence. In this article, we present the underlying mechanisms of fibrosis, current experimental and clinical evidence of the reversibility of liver fibrosis/cirrhosis, and new agents with therapeutic potential for liver fibrosis.

Galectin-3 regulates inflammasome activation in cholestatic liver injury

Macrophage activation is an important feature of primary biliary cholangitis (PBC) pathogenesis and other cholestatic liver diseases. Galectin-3 (Gal3), a pleiotropic lectin, is produced by monocytic cells and macrophages. However, its role in PBC has not been addressed. We hypothesized that Gal3 is a key to induce NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome in macrophages and in turn to propagate proinflammatory IL-17 signaling. In liver tissues from patients with PBC and dnTGF-βRII mice, a model of autoimmune cholangitis, the expression of Gal3, NLRP3, and the adaptor protein adaptor apoptosis-associated speck-like protein was induced, with the downstream activation of caspase-1 and IL-1β. In wild-type hepatic macrophages, deoxycholic acid induced the association of Gal3 and NLRP3 with direct activation of the inflammasome, resulting in an increase in IL-1β. Downstream retinoid-related orphan receptor C mRNA, IL-17A, and IL-17F were induced. In Gal3-/- macrophages, no inflammasome activation was detected. To confirm the key role of Gal3 in the pathogenesis of cholestatic liver injury, we generated dnTGF-βRII/galectin-3-/- (dn/Gal3-/-) mice, which showed impaired inflammasome activation along with significantly improved inflammation and fibrosis. Taken together, our data point to a novel role of Gal3 as an initiator of inflammatory signaling in autoimmune cholangitis, mediating the activation of NLRP3 inflammasome and inducing IL-17 proinflammatory cascades. These studies provide a rationale to target Gal3 in autoimmune cholangitis and potentially other cholestatic diseases.-Tian, J., Yang, G., Chen, H.-Y., Hsu, D. K., Tomilov, A., Olson, K. A., Dehnad, A., Fish, S. R., Cortopassi, G., Zhao, B., Liu, F.-T., Gershwin, M. E., Török, N. J., Jiang, J. X. Galectin-3 regulates inflammasome activation in cholestatic liver injury.

Targeting Hepatic Fibrosis in Autoimmune Hepatitis

Hepatic fibrosis develops or progresses in 25 % of patients with autoimmune hepatitis despite corticosteroid therapy. Current management regimens lack reliable noninvasive methods to assess changes in hepatic fibrosis and interventions that disrupt fibrotic pathways. The goals of this review are to indicate promising noninvasive methods to monitor hepatic fibrosis in autoimmune hepatitis and identify anti-fibrotic interventions that warrant evaluation. Laboratory methods can differentiate cirrhosis from non-cirrhosis, but their accuracy in distinguishing changes in histological stage is uncertain. Radiological methods include transient elastography, acoustic radiation force impulse imaging, and magnetic resonance elastography. Methods based on ultrasonography are comparable in detecting advanced fibrosis and cirrhosis, but their performances may be compromised by hepatic inflammation and obesity. Magnetic resonance elastography has excellent performance parameters for all histological stages in diverse liver diseases, is uninfluenced by inflammatory activity or body habitus, has been superior to other radiological methods in nonalcoholic fatty liver disease, and may emerge as the preferred instrument to evaluate fibrosis in autoimmune hepatitis. Promising anti-fibrotic interventions are site- and organelle-specific agents, especially inhibitors of nicotinamide adenine dinucleotide phosphate oxidases, transforming growth factor beta, inducible nitric oxide synthase, lysyl oxidases, and C-C chemokine receptors types 2 and 5. Autoimmune hepatitis has a pro-fibrotic propensity, and noninvasive radiological methods, especially magnetic resonance elastography, and site- and organelle-specific interventions, especially selective antioxidants and inhibitors of collagen cross-linkage, may emerge to strengthen current management strategies.

Gaps in Aging Research as it Applies to Rheumatologic Clinical Care

The incidence and prevalence of rheumatologic conditions are increasing and the rheumatology workforce must be aware of aging-specific issues. This article reviews specific barriers to understanding the biology of aging and aging-related mechanisms that may underlie development of rheumatologic diseases in older adults. It summarizes gaps in the assessment, outcomes measurement, and treatment of these diseases in this unique population. It also highlights potential solutions to these barriers and suggests possible ways to bridge the gap, from a research and education standpoint, so that clinicians can be better prepared to effectively manage older adults with rheumatologic conditions.

Emerging drugs for the treatment of Primary Biliary Cholangitis

INTRODUCTION

Primary biliary cholangitis (PBC) is an autoimmune chronic disease of the liver that can progress to cirrhosis and hepatocellular carcinoma. It affects approximately 1 in 4,000 with a 10:1 female to male ratio. The diagnosis of PBC can be made based on serum antimitochondrial antibodies (AMA) in a patient with abnormally high serum alkaline phosphatase after ruling out other causes of cholestasis and biliary obstruction. Genome-wide association studies have revealed several human leukocyte antigen (HLA) and non-HLA risk loci in PBC, and complex environmental-host immunogenetic interactions are believed to underlie the etiopathogenesis of the disease. Fatigue and pruritus are the most common and often problematic symptoms; although often mild, these can be severe and life-alternating in a subset of patients. Ursodeoxycholic acid (UDCA) is the only drug approved by the United States Food and Drug Administration for the treatment of PBC. Clinical trials have shown that UDCA significantly improves transplant-free survival. However, nearly 40% of PBC patients do not respond adequately to PBC and are at higher risk for serious complications when compared to PBC patients with complete response to UDCA.

AREAS COVERED

Here we provide a detailed discussion regarding novel therapeutic agents and potential areas for further investigation in PBC-related research.

EXPERT OPINION

Results of ongoing clinical trials and emerging treatment paradigms for PBC will likely further improve medical management of this disorder in the near future.

Nature and Implications of Oxidative and Nitrosative Stresses in Autoimmune Hepatitis

Oxidative and nitrosative stresses can damage cellular membranes, disrupt mitochondrial function, alter gene expression, promote the apoptosis and necrosis of hepatocytes, and increase fibrosis in diverse acute and chronic liver diseases, including autoimmune hepatitis. The objectives of this review are to describe the mechanisms of oxidative and nitrosative stresses in inflammatory liver disease, indicate the pathogenic implications of these stresses in autoimmune hepatitis, and suggest investigational opportunities to develop interventions that counter them. The principal antioxidant defenses, including glutathione production, the activities of antioxidant enzymes, and the release of the nuclear factor erythroid 2-related factor 2, may be inadequate or suppressed by transforming growth factor beta. The generation of reactive oxygen species can intensify nitrosative stress, and this stress may not be adequately modulated by the thioredoxin-thioredoxin reductase system and induce post-translational modifications of proteins that further disrupt hepatocyte function. The unfolded protein response and autophagy may be unable to restore redox stability, meet metabolic demands, and maintain hepatocyte survival. Emerging interventions with highly selective site- and organelle-specific actions may improve outcomes, and they include inhibitors of nicotinamide adenine dinucleotide phosphate oxidase, nitric oxide synthase, and transforming growth factor beta. Pharmacological manipulation of nuclear transcription factors may favor expression of antioxidant genes, and stimulation of chaperone proteins within the endoplasmic reticulum and modulation of autophagy may prevent hepatic fibrosis and enhance cell survival. These interventions constitute investigational opportunities to improve the management of autoimmune hepatitis.

Preventive effects of dietary walnuts on high-fat-induced hepatic fat accumulation, oxidative stress and apoptosis in mice

We hypothesized that dietary walnut would prevent high-fat-diet (HFD)-induced hepatic apoptosis based on its antioxidant properties. Male C57BL/6J mice were fed a rodent chow or HFD (45% energy-derived)±walnuts (21.5% energy-derived) for 6 weeks. Liver histological and biochemical analyses revealed significantly elevated fat accumulation in mice fed HFD compared to mice fed the chow or HFD±walnuts. Walnut supplementation prevented HFD-mediated alteration of the levels of key proteins in lipid homeostasis such as Sirt1, AMPK and FAS, leading to decreased fat accumulation. In addition, walnut supplementation to HFD significantly decreased the hepatic levels of cytochrome P450-2E1, nitrated proteins and lipid peroxidation. Furthermore, walnut supplementation decreased the activated cell-death-associated p-JNK and p-p38K accompanied with increased hepatocyte apoptosis in HFD group. The beneficial effects of dietary walnut likely result, at least partially, from its antioxidant ingredients and attenuating HFD-induced hepatic steatosis, nitroxidative stress and apoptosis.

Diagnosis and Management of Autoimmune Hepatitis: Current Status and Future Directions

Autoimmune hepatitis is characterized by autoantibodies, hypergammaglobulinemia, and interface hepatitis on histological examination. The features lack diagnostic specificity, and other diseases that may resemble autoimmune hepatitis must be excluded. The clinical presentation may be acute, acute severe (fulminant), or asymptomatic; conventional autoantibodies may be absent; centrilobular necrosis and bile duct changes may be present; and the disease may occur after liver transplantation or with features that suggest overlapping disorders. The diagnostic criteria have been codified, and diagnostic scoring systems can support clinical judgment. Nonstandard autoantibodies, including antibodies to actin, α-actinin, soluble liver antigen, perinuclear antineutrophil antigen, asialoglycoprotein receptor, and liver cytosol type 1, are tools that can support the diagnosis, especially in patients with atypical features. Prednisone or prednisolone in combination with azathioprine is the preferred treatment, and strategies using these medications in various doses can ameliorate treatment failure, incomplete response, drug intolerance, and relapse after drug withdrawal. Budesonide, mycophenolate mofetil, and calcineurin inhibitors can be considered in selected patients as frontline or salvage therapies. Molecular (recombinant proteins and monoclonal antibodies), cellular (adoptive transfer and antigenic manipulation), and pharmacological (antioxidants, antifibrotics, and antiapoptotic agents) interventions constitute future directions in management. The evolving knowledge of the pathogenic pathways and the advances in technology promise new management algorithms.

Methane-rich saline protects against concanavalin A-induced autoimmune hepatitis in mice through anti-inflammatory and anti-oxidative pathways

Methane is a common gas which has been reported to play a protective role in organ injury and presents an anti-inflammatory property. However, its effects on Concanavalin A (Con A)-induced autoimmune hepatitis (AIH) remain unknown. Thus, the aim of this study was to investigate the effects of methane on Con A-induced autoimmune hepatitis in mice and its underlying mechanism. Autoimmune hepatitis was induced by Con A (15 mg/kg) in healthy C57BL/6 mice and methane-rich saline (MS) (20 ml/kg) was intraperitoneally injected 30 min after the challenge with Con A. We found that methane treatment significantly reduced the elevated serum aminotransferase levels and ameliorated liver pathological damage. Furthermore, methane treatment obviously suppressed the secretion of proinflammatory cytokines including tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-6 (IL-6) and interleukin-1β (IL-1β) and increased anti-inflammatory cytokine interleukin-10 (IL-10). Moreover, we found that the levels of malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) were highly increased while the activities of superoxide dismutase (SOD) and catalase (CAT) were decreased in liver with the injection of Con A, which was reversed by methane. Also, the data demonstrated that the phosphorylated IκB, NF-κB and P38 MAPK in liver were significantly down-regulated by methane. These results suggested that methane protected liver against Con A-induced injury through anti-inflammatory and anti-oxidative pathways.

Transitioning from Idiopathic to Explainable Autoimmune Hepatitis

Autoimmune hepatitis lacks an identifiable cause, and its diagnosis requires the exclusion of etiologically defined diseases that resemble it. Insights into its pathogenesis are moving autoimmune hepatitis from an idiopathic to explainable disease, and the goal of this review is to describe the insights that are hastening this transition. Two types of autoimmune hepatitis are justified by serological markers, but they also have distinctive genetic associations (DRB1 and DQB1 genes) and autoantigens. DRB1 alleles are the principal susceptibility factors in white adults, and a six amino acid sequence encoded in the antigen-binding groove of class II molecules of the major histocompatibility complex can influence the selection of autoantigens. Polymorphisms, including variants of SH2B3 and CARD10 genes, may affect immune reactivity and disease severity. The cytochrome mono-oxygenase, CYP2D6, is the autoantigen associated with type 2 autoimmune hepatitis, and it shares homologies with multiple viruses that might promote self-intolerance by molecular mimicry. Chemokines, especially CXCL9 and CXCL10, orchestrate the migration of effector cells to sites of injury and are associated with disease severity. Cells of the innate and adaptive immune responses promote tissue damage, and possible deficiencies in the number and function of regulatory T cells may facilitate the injurious process. Receptor-mediated apoptosis is the principal mechanism of hepatocyte loss, and cell-mediated and antibody-dependent mechanisms of cytotoxicity also contribute. Insights that explain autoimmune hepatitis will allow triggering exogenous antigens to be characterized, risk management to be improved, prognostic indices to be refined, and site-specific therapeutic interventions to emerge.

Low SOD activity is associated with overproduction of peroxynitrite and nitric oxide in patients with acute coronary syndrome

OBJECTIVE

The present study was undertaken to evaluate the variation of the oxidative/nitrosative stress status in a population of subjects; with acute coronary syndrome (ACS), and examine its possible implication in plaque rupture which is the main mechanism in the pathophysiology of ACS.

PATIENTS AND METHODS

We made this study on 50 men with ACS and 50 age and sex matched healthy controls. Nitrosative/oxidative stress markers including; nitric oxide, superoxide anion levels, superoxide dismutase (SOD) activity and peroxynitrite levels were evaluated in blood samples of patients and controls.

RESULTS

Compared with healthy subjects, coronary patients had significantly higher nitric oxide, peroxynitrite and superoxide anion concentrations in both plasma and erythrocytes associated to significant decrease of SOD activity. Erythrocytes peroxynitrite concentration was negatively correlated with the antioxidant enzyme activity (SOD).

CONCLUSION

Our results show a significant accumulation of both intracellular and plasma pro-oxidants with a concomitant decrease in the SOD scavenging activity in ACS patients. Both seem to be associated with plaque rupture and ischemia observed in ACS.

Nitric oxide is a potential mediator of hepatic inflammation and fibrogenesis in autoimmune hepatitis

BACKGROUND

Despite advances in the understanding of the pathophysiological basis of autoimmune hepatitis (AIH), it is still difficult to delineate the mechanisms involved in progression from hepatic inflammation toward fibrosis. Our aim was to study serum concentrations of NO in AIH of different histological severity and possible effects of immunosuppressive therapy on NO production.

MATERIALS AND METHODS

We studied serum NO metabolites (NOx) in 47 consecutive patients with AIH and in 28 age- and sex-matched controls.

RESULTS

Serum NOx concentrations were higher in AIH patients than in controls (10.3 (4.5-27.3 µmol/L) vs. 4.3 (1.6-14.3 µmol/L), p < 0.001). According to liver histology, median NOx concentrations were significantly higher in patients with severe interface hepatitis compared to patients with mild-moderate interface hepatitis (12.3 (4.5-27.3 µmol/L) vs. 9.3 (4.6-20.3 µmol/L), p = 0.029). Similarly, serum NOx concentrations were significantly higher in patients with advanced fibrosis than in those with early fibrosis (12.2 (4.6-27.3 µmol/L) vs. 9.3 (6.6-12.8 µmol/L), p = 0.018). NOx concentrations decreased in 16 AIH patients who were tested also after biochemical remission was achieved (12.6 (4.5-22.8 µmol/L) at baseline and 5.9 (2.8-10.5 µmol/L) after remission, p = 0.001).

CONCLUSION

This study shows that serum NOx levels are associated with the histological severity of AIH. Hepatocyte inflammation and injury may activate hepatic stellate cells and kupffer cells, and the consequences may include release of NO, which ultimately promotes hepatic fibrosis. Immunosuppressive therapy inhibits this process and the production of NO.

Oxidative stress and antioxidant status in patients with autoimmune liver diseases

OBJECTIVE

To estimate oxidative stress and antioxidant components during different stages of autoimmune liver diseases and assess their possible implication on disease progression.

METHODS

We determined several markers of oxidative injury (isoprostane, aldehydes, protein carbonyls, 3-nitrotyrosine, and myeloperoxidase) and antioxidant components (glutathione, glutathione peroxidase, glutathione reductase, superoxide dismutase, and catalase) in whole blood, serum, and urine in 49 patients with autoimmune cholestatic liver diseases (AC) and 36 patients with autoimmune hepatitis (AIH) and healthy subjects matched for sex and age.

RESULTS

Both AC and AIH patients had increased levels of all lipid and protein oxidative injury products and significantly decreased whole blood glutathione levels compared to controls. AIH patients had significantly higher levels of aldehydes and glutathione peroxidase activity and significantly lower protein carbonyl levels compared to AC patients. Protein carbonyl and isoprostane levels increased and glutathione levels decreased gradually with progression from mild fibrosis to severe fibrosis and cirrhosis in both AC and AIH patients. In addition, both cirrhotic AC and AIH patients had significantly higher protein carbonyls compared to non-cirrhotics.

DISCUSSION

We provide novel findings in support of a major contribution of oxidant/antioxidant imbalance in the progression of liver injury in AC and AIH.

Review article: The prevention and reversal of hepatic fibrosis in autoimmune hepatitis

BACKGROUND

Immunosuppressive treatment of autoimmune hepatitis can prevent or reverse hepatic fibrosis, but these anti-fibrotic effects are inconsistent secondary gains.

AIM

To describe the anti-fibrotic effects of current therapies for autoimmune hepatitis, discuss the pathogenic mechanisms of hepatic fibrosis that might be targeted by anti-fibrotic interventions, indicate the non-invasive diagnostic tests of hepatic fibrosis that must be validated in autoimmune hepatitis and to suggest promising treatment opportunities.

METHODS

Studies cited in PubMed from 1972 to 2013 for autoimmune hepatitis, hepatic fibrosis, cirrhosis, anti-fibrotic therapy and non-invasive tests of hepatic fibrosis were selected.

RESULTS

Hepatic fibrosis improves in 53-57% of corticosteroid-treated patients with autoimmune hepatitis; progressive fibrosis slows or is prevented in 79%; and cirrhosis may be reversed. Progressive hepatic fibrosis is associated with liver inflammation, and the inability to fully suppress inflammatory activity within 12 months is associated with progression to cirrhosis (54%) and death or need for liver transplantation (15%). Liver tissue examination remains the gold standard for assessing hepatic fibrosis, but laboratory and radiological tests may be useful non-invasive methods to measure the fibrotic response. Severe liver inflammation can confound radiological assessments, and the preferred non-invasive test in autoimmune hepatitis is uncertain. Individualised treatment adjustments and adjunctive anti-fibrotic therapies are poised for study in this disease.

CONCLUSIONS

The prevention and reversal of hepatic fibrosis are achievable objectives in autoimmune hepatitis. Strategies that evaluate individualised therapies adjusted to the rapidity and completeness of the inflammatory response, and the use of adjunctive anti-fibrotic interventions, must be evaluated.

The role of vitamin d in autoimmune hepatitis

Autoimmune hepatitis is an inflammation of the liver characterized by the presence of peri-portal hepatitis, hypergammaglobulinemia, and the serum autoantibodies. The disease is classified into 2 distinct types according to the nature of auto-antibodies. Disturbances of the calcium-parathyroid hormone-vitamin D axis are frequently associated with chronic liver disease. Patients with AIH have a high prevalence of vitamin D deficiency. Genetic studies have provided the opportunity to determine which proteins link vitamin D to AIH pathology, namely, the major histocompatibility complex class II molecules, vitamin D receptors, toll-like receptors, cytotoxic T lymphocyte antigen-4, cytochrome P450 CYP2D6, regulatory T cells (Tregs) and the forkhead/winged helix transcription factor 3. Vitamin D also exerts its effect on AIH through non-genomic factors, namely, mitogen-activated protein kinase signaling pathways, γδT cells, interferon-gamma nitric oxide synthase, and reactive oxygen stress. In conclusion, vitamin D may have a beneficial role in AIH and improves liver function in concanavalin A-induced mouse AIH. Calcitriol is best used for AIH because it is the active form of a vitamin D3 metabolite and its receptors are present in sinusoidal endothelial cells, Kupffer cells, stellate cells of normal livers, and the biliary cell line.

Angiopoietin-2 Serum Levels Improve Noninvasive Fibrosis Staging in Chronic Hepatitis C: A Fibrogenic-Angiogenic Link

AIMS

Accurate liver fibrosis staging is crucial for the management of chronic hepatitis C (CHC). The invasiveness and cost burden of liver biopsy have driven the search for new noninvasive biomarkers of fibrosis. Based on the link between serum angiopoietin-1 and 2 levels and CHC progression, we aimed to determine the value of these angiogenic factors as noninvasive biomarkers of liver fibrosis.

METHODS

Serum levels of angiopoietin-1 and -2 were measured by ELISA in 108 CHC patients who underwent pretreatment liver biopsy. The correlation between angiopoietins and clinical and demographic variables with liver fibrosis was analyzed by univariate regression. Significant factors were then subjected to multivariate analysis, from which we constructed a novel noninvasive liver fibrosis index (AngioScore), whose performance was validated in an independent series of 71 CHC patients. The accuracy of this model was compared with other documented fibrosis algorithms by De Long test.

RESULTS

Angiopoietins correlated significantly with hepatic fibrosis; however, only angiopoietin-2 was retained in the final model, which also included age, platelets, AST, INR, and GGT. The model was validated and behaved considerably better than other fibrosis indices in discriminating all, significant, moderate and severe liver fibrosis (0.886, 0.920, 0.923). Using clinically relevant cutoffs, we classified CHC patients by discarding significant fibrosis and diagnosing moderate and severe fibrosis with greater accuracy, sensitivity, and specificity.

CONCLUSIONS

Our novel noninvasive liver fibrosis model, based on serum angiopoietin-2 levels, outperforms other indices and should help substantially in managing CHC and monitoring long-term follow-up prognosis.

Effects of modulating M3 muscarinic receptor activity on azoxymethane-induced liver injury in mice

Previously, we reported that azoxymethane (AOM)-induced liver injury is robustly exacerbated in M3 muscarinic receptor (M3R)-deficient mice. We used the same mouse model to test the hypothesis that selective pharmacological modulation of M3R activity regulates the liver injury response. Initial experiments confirmed that giving a selective M3R antagonist, darifenacin, to AOM-treated mice mimicked M3R gene ablation. Compared to vehicle controls, mice treated with the M3R antagonist had reduced survival and increased liver nodularity and fibrosis. We next assessed AOM-induced liver injury in mice treated with a selective M3R agonist, pilocarpine. After pilocarpine treatment, stimulation of post-M3R signaling in the liver was evidenced by ERK and AKT activation. In contrast to the damaging effects of the M3R antagonist, administering pilocarpine to AOM-treated mice significantly attenuated hepatic stellate cell activation, collagen deposition, bile ductule proliferation, and liver fibrosis and nodularity. As anticipated from these findings, livers from pilocarpine-treated mice exhibited reduced expression of key players in fibrosis (α1 collagen, α-smooth muscle actin, TGF-β1, PGDF, TGF-β1R, PGDFR) and decreased mRNA levels for molecules that regulate extracellular matrix formation (TIMP-1, TIMP-2, MMP-2, MMP-13). Cleaved caspase-3, nitrotyrosine and BrdU immunostaining provided evidence that pilocarpine treatment reduced hepatocyte apoptosis and oxidative stress, while increasing hepatocyte proliferation. Collectively, these findings identify several downstream mechanisms whereby M3R activation ameliorates toxic liver injury. These novel observations provide a proof-of-principle that selectively stimulating M3R activation to prevent or diminish liver injury is a therapeutic strategy worthy of further investigation.

In vivo modulation of iNOS pathway in hepatocellular carcinoma by Nigella sativa

OBJECTIVE

Nitric oxide (NO) and inducible nitric oxide synthase enzyme (iNOS) have been implicated in various tumors. Hepatocellular carcinoma is a highly aggressive form of solid tumor. The lack of effective therapy necessitates the introduction of novel therapeutic strategies to counter this disease. Nigella sativa (NS) has been shown to have specific health benefits. The aim of this study was to investigate the in vivo modulation of the iNOS pathway by NS ethanolic extract (NSEE) and the implications of this effect as an antitumor therapeutic approach against diethylnitrosamine (DENA)-induced hepatocarcinogenesis.

METHODS

Rats were divided into four groups, normal control, NSEE control, cancer control, and NSEE-DENA groups. The diagnosis of cancer was based on alpha-fetoprotein (AFP) levels and histological variations. Serum NO, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) levels and serum iNOS activity were measured. Liver iNOS expression was investigated by reverse transcriptase (RT)-PCR and western blot assays.

RESULTS

Serum AFP, NO, TNF-α, and IL-6 levels and iNOS enzyme activity were significantly increased in rats treated with DENA. Significant up-regulation of liver iNOS mRNA and protein expression was also observed. Subsequent treatment with NSEE significantly reversed these effects and improved the histopathological changes in malignant liver tissue which appeared after treatment with DENA, without any toxic effect when given alone.

CONCLUSION

These results provide evidence that attenuation of the iNOS pathway and suppression of the inflammatory response mediated by TNF-α, and IL-6 could be implicated in the antitumor effect of NSEE. As such, our findings hold great promise for the utilization of NS as an effective natural therapeutic agent in the treatment of hepatocarcinogenesis.

Chlorogenic acid reduces liver inflammation and fibrosis through inhibition of toll-like receptor 4 signaling pathway

Chlorogenic acid (CGA) is a type of polyphenol with anti-inflammatory, antioxidant activities. Our previous studies showed CGA could efficiently inhibit carbon tetrachloride (CCl(4))-induced liver fibrosis in rats. However, the specific underlying mechanism remains unclear. The aim of this study is to investigate the effects of CGA on liver inflammation and fibrosis induced by CCl(4) and whether they are related to inhibition of toll-like receptor 4 (TLR4) signaling pathway. Male Sprague-Dawley (SD) rats were administrated CCl(4) together with or without CGA for 8 weeks. Histopathological and biochemical analyses were carried out. The mRNA and protein expression levels of proinflammatory and profibrotic mediators were detected by RT-PCR and Western blot, respectively. The levels of serum proinflammatory cytokines were detected by ELISA. CGA significantly attenuated CCl(4)-induced liver damage and symptoms of liver fibrosis, accompanied by reduced serum transaminase levels, collagen I and α-smooth muscle actin (α-SMA) expression. As compared with the CCl(4)-treated group, the expression levels of TLR4, myeloid differentiation factor 88 (MyD88), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were reduced in the treatment group of CCl(4) and CGA, whereas bone morphogenetic protein and activin membrane-bound inhibitor (Bambi) expression was increased. CGA also suppressed CCl(4) induced nuclear factor-κB (NF-κB) activation. Moreover, the hepatic mRNA expression and serum levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) were significantly increased in CCl(4)-treated rats and attenuated by co-treatment with CGA. Our data indicate that CGA can efficiently inhibit CCl(4)-induced liver fibrosis in rats and the protective effect may be due to the inhibition of TLR4/MyD88/NF-κB signaling pathway.

Oxidative stress and benefits of antioxidant agents in acute and chronic hepatitis

CONTEXT

Oxidative damage due to oxidative stress is the failure of the cell's defense against the deleterious effects of harmful agents by means of its numerous autoprotective mechanisms. oxidative stress is a key impairment induced by various conditions, including atherosclerosis, hypertension, ischemia-reperfusion, hepatitis, pancreatitis, cancer, and neurodegenerative diseases.

EVIDENCE ACQUISITION

Oxidative stress is a common pathogenetic mechanism contributing to the initiation and progression of hepatic damage in cases of inflammatory liver disorders, including acute and chronic hepatitis. Antioxidant administration is a good therapeutic strategy for the treatment of hepatitis.

RESULTS

Our comprehensive review of the literature revealed that contradictory results have been obtained with many antioxidants and antioxidant agents.

CONCLUSION

Since clinical studies to date have generally involved testing of the effects of antioxidant mixtures containing more than 2 antioxidants and also have been limited because of toxic effects of high doses of some antioxidants, antioxidant therapy for acute and chronic hepatitis needs further study.

Long-term ursodeoxycholate improves circulating redox changes in primary biliary cirrhotic patients

BACKGROUND AND AIMS

Cholestasis is associated with systemic and hepatic oxidative and nitrosative stress; in this scenario, the conjugated hydrophilic bile salt ursodeoxycholate (UDCA) might play a protective role.

METHODS

Circulating oxidative and nitrosative stress markers were assessed in patients with primary biliary cirrhosis (PBC) before and during UDCA (15-20mg/kg/day) therapy.

RESULTS

In patients with stage I-II PBC, UDCA improved ALT and alkaline phosphatase levels and near normalized serum thioredoxin (1.97 ± 0.37 vs 2.41 ± 0.39 nmol/L), nitrotyrosine (15 ± 4 vs 22 ± 7 nmol/L), nitrosothiols (144 ± 28 vs 205 ± 84 nmol/L) and K-18 levels (162 ± 21 vs 228 ± 33 U/L). Conversely, less marked changes were noted in patients with stages III-IV who showed lower thioredoxin (1.01 ± 0.31 nmol/L), higher nitrosothiols (605 ± 64 nmol/L), nitrotyrosine (62 ± 13 nmol/L) and K-18 levels (521 ± 57 U/L). Overall, thioredoxin was inversely related with nitrotyrosine (r=-0.838, P<0.001) and K-18 (r=-0.838, P<0.001) levels. Nitrosothiols and K-18 were linearly and significantly related with nitrotyrosine (r=0.862, P<0.001; r=0.894, P<0.001, respectively).

CONCLUSIONS

Oxidative and nitrosative changes in patients with PBC are effectively counteracted by UDCA. The protective effect of UDCA, however, are limited to early disease stages and progressively diminishes with ongoing cholestasis.

Evaluation of nitrite/nitrate levels in relation to oxidative stress parameters in liver cirrhosis

BACKGROUND AND OBJECTIVE

Nitric oxide and reactive oxygen species have been implicated in several pathophysiological events leading to fibrosis and cirrhosis. The aim of the present study was to investigate the possible contribution of peroxynitrite (formed by the interaction of nitric oxide and superoxide anion) in the pathophysiology of cirrhosis.

METHODS

Twenty-six cirrhotic patients classified as Child-Pugh A, and seven as Child-Pugh B, were included in the study, and nine healthy volunteers served as controls. Levels of nitrite/nitrate (NOx), thiobarbituric acid-reactive substances (TBARS), nitrotyrosine (peroxynitrite marker), superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH) were measured in blood samples.

RESULTS

NOx, TBARS, CAT, SOD and GSH levels were higher in cirrhosis patients than in the controls (NOx: 0.17 ± 0.02, 0.95 ± 0.12, 1.3 ± 0.1; TBARS: 2.0 ± 0.05, 4.6 ± 0.3, 5 ± 0.3; CAT: 1.8 ± 0.1, 4 ± 0.3, 4.5 ± 0.4; SOD: 1.8 ± 0.2, 4.8 ± 0.5, 7 ± 0.4; and GSH: 1.3 ± 0.05, 3.6 ± 0.3, 4.5 ± 0.6 in controls, and Child-Pugh A and B patients, respectively). However, there were no differences in nitrotyrosine levels across these groups (controls: 11.4 ± 0.4; Child-Pugh A: 11.1 ± 0.4; Child-Pugh B: 11.9 ± 1.6). NOx levels showed significant and strongly positive correlations with TBARS, SOD, CAT and GSH levels. In contrast, no correlations were found between either NOx or TBARS and nitrotyrosine levels.

CONCLUSION

Nitric oxide and reactive oxygen species, but not peroxynitrite, are overproduced in patients with cirrhosis in spite of evidence of an increase in antioxidant defenses. This suggests that therapeutic measures aimed at attenuating oxidative stress as well as increasing antioxidant defenses may well benefit patients with cirrhosis.

Liver disease and erythropoietic protoporphyria: A concise review

The porphyries are a group of metabolic disorders characterized by deficiencies in the activity of enzymes involved in the biosynthesis of heme. In erythropoietic protoporphyria (EPP), in the majority of cases an autosomal dominant disease, there is a mutation of the gene that encodes ferrochelatase (FECH). FECH deficiency is associated with increased concentrations of protoporphyrin in erythrocytes, plasma, skin and liver. The prevalence of this inherited disorder oscillates between 1:75 000 and 1:200 000. Clinical manifestations of EPP appear in early infancy upon first exposure to the sun. Nevertheless, approximately 5%-20% of patients with EPP develop liver manifestations. Retention of protoporphyrin in the liver is associated with cholestatic phenomena and oxidative stress that predisposes to hepatobiliary disease of varying degrees of severity, such as cholelithiasis, mild parenchymal liver disease, progressive hepatocellular disease with end-stage liver disease and acute liver failure. Liver damage is the major risk in EPP patients, so surveillance and frequent clinical and biochemical liver follow-up is mandatory. The diagnostic approach consists in detecting increased levels of protoporphyrin, decreased activity of FECH and genetic analysis of the FECH gene. A variety of non-surgical therapeutic approaches have been adopted for the management of EPP associated with liver disease, but none of these has been shown to be unequivocally efficacious. Nevertheless, some may have a place in preparing patients for liver transplantation. Liver transplantation does not correct the constitutional deficiency of FECH. Consequently, there is a risk of recurrence of liver disease after liver transplantation as a result of continuing overproduction of protoporphyrin. Some authors recommend that bone marrow transplantation should be considered in liver allograft recipients to prevent recurrence of hepatic disease.

Hepatoprotective effects of antioxidants in chronic hepatitis C

We have read with interest the paper published in issue 2, volume 16 of World Journal of Gastroenterology 2010 by Nakamura et al, demonstrating that the antioxidant resveratrol (RVT) enhances hepatitis C virus (HCV) replication, consequently, they conclude that RVT is not a suitable antioxidant therapy for HCV chronic infection. The data raise some concern regarding the use of complementary and alternative medicine since the most frequent supplements taken by these patients are antioxidants or agents that may be beneficial for different chronic liver diseases. A recent study by Vidali et al on oxidative stress and steatosis in the progression of chronic hepatitis C concludes that oxidative stress and insulin resistance contribute to steatosis, thus accelerating the progression of fibrosis. We are particularly interested in investigating how the oxidative and nitrosative stress mechanisms are involved in the pathogenesis of different chronic liver diseases.

Nitric oxide plays a crucial role in the development/progression of nonalcoholic steatohepatitis in the choline-deficient, l-amino acid-defined diet-fed rat model

BACKGROUND

The pathogenesis of nonalcoholic steatohepatitis (NASH) is still unclear. Recently, the 2-hit hypothesis was proposed, in which nitric oxide production, representing oxidative stress, was proposed as a very important candidate for the second hit.

METHODS

The total study period was 10 weeks. A total of 20 rats were randomly divided into 2 groups. Group 1 was administered the Choline-Deficient, l-Amino Acid-Defined diet to produce a NASH model, and Group 2 as control received the Choline-Sufficient, l-Amino Acid-defined diet. The blood and tissue concentrations of nitrate + nitrite were measured using the Griess reagent and the expression levels of inducible nitric oxide synthase (iNOS) proteins and mRNA was determined by Western blotting.

RESULTS

In regard to nitric oxide (NO) and NO metabolites, there were significant differences in the blood (especially portal venous blood) as well as tissue (liver and visceral fat) concentrations between the 2 animal groups; the amounts of NO metabolites in the tissues were much higher in the NASH models. The level of nitrotyrosine was much markedly higher in the NASH models than in the controls. In regard to the tissue expression of iNOS a significant difference between the 2 groups was found in the visceral fat, especially in the mesenterium.

CONCLUSIONS

Based on these results, we hypothesize that the iNOS expression and NO levels in the visceral fat increase, with increased diffusion of NO and its metabolites into the liver, resulting in increased nitrotyrosine formation in the liver; this, in turn, induces inflammation, apoptosis, and fibrosis in the liver, which are one of the characteristic features of NASH.

Influence of inducible nitric oxide synthase polymorphisms in Japanese patients with non-alcoholic fatty liver disease

AIM

Genetic factors as well as environmental factors play an important role in the development of non-alcoholic fatty liver disease (NAFLD). Recently, inducible nitric oxide synthase (iNOS) was significantly higher in the severest form of non-alcoholic steatohepatitis (NASH), and nitric oxide (NO) has been determined to play an important role in the process of fibrosis in NASH. In this study, we investigated iNOS gene polymorphisms for associations with NAFLD.

METHODS

A total of 115 NAFLD patients, consisting of 65 patients with NASH and 50 patients with simple steatosis, in whom a positive diagnosis had been made by liver biopsy, and 435 healthy control subjects, were recruited into this study.

RESULTS

We investigated 10 single nucleotide polymorphisms (SNP) of the iNOS gene, one of which, rs1060822, had the lowest P-value in the allele frequency model (P = 0.00078) with an odds ratio (95% confidence interval) of 0.49 (0.32-0.75). Four SNP, rs2297510, rs2297511, rs2797512 and rs1060822, were significantly associated with NAFLD, even when the most conservative Bonferroni's correction was applied. Linkage disequilibrium analysis revealed that SNP rs1060822 and three other SNP, rs2297510, rs2297511 and rs2797512, were in the same block. We also investigated associations between rs1060822 genotypes and the fibrosis index, and the results of the analysis revealed an additive increase in the fibrosis index and intrahepatic iNOS mRNA expression in the patients with the T allele of rs1060822.

CONCLUSION

This is the first study to identify genetic variations in iNOS that may influence the risk of NAFLD and liver fibrosis in NAFLD.

Impaired indoleamine 2,3-dioxygenase production contributes to the development of autoimmunity in primary biliary cirrhosis

The immunomodulatory effects of the tryptophan-catabolizing enzyme indoleamine 2,3-dioxygenase (IDO) have been elucidated at a cellular level and implicated in the pathogenesis of several complex diseases. Defects within the regulatory T cell compartment are one of the characteristics of primary biliary cirrhosis (PBC), an autoimmune chronic cholestatic liver disease, a phenotype that has also been shown in disease-mimicking animal models of this disease. We hypothesized that IDO dysregulation could lead to altered frequency and/or function of T cells at the level of antigen processing/presentation and we thus investigated IDO in peripheral monocytes and bile duct cells from patients with PBC. Both expression and activation manifested an impaired IFN-gamma response in peripheral monocytes while a peculiar IDO expression profile in bile duct cells characterized early stage PBC. Further, we observed an increased frequency of a gain-of-function SNP within the TGF-beta promoter region, a molecule known to suppress IDO transcription. In conclusion, we submit that an impaired IDO induction characterizes PBC and might represent a contributing factor in disease pathogenesis in association with several specific defects in the target tissue.

Inducible nitric oxide synthase and histopathological correlation in chronic viral hepatitis

BACKGROUND

Chronic liver disorders represent a serious health problem. Nitric oxide (NO) synthesized by inducible nitric oxide synthase (iNOS) can function as an antimicrobial agent able to kill or reduce replication of microorganisms, and plays an important role in immune regulation. This study was undertaken to evaluate the expression of iNOS in chronic viral hepatitis and its relation to histopathology.

METHODS

This study included 56 patients with chronic viral hepatitis (38 hepatitis B, 18 hepatitis C). There were 35 men and 21 women with a mean age of 38.6+/-21.731 years. A modified form of the histology activity index (HAI) designed by Ishak and colleagues was used to assess grading and staging of chronic viral hepatitis. The needle biopsy specimens were fixed in 10% formalin and routinely processed. Routine hematoxylin-eosin, periodic acid-Schiff, and reticulin staining, and iNOS immunoperoxidase technique were performed on paraffin-embedded tissues.

RESULTS

We demonstrated that all liver samples had a marked iNOS expression, with a diffuse distribution pattern. iNOS consistently labeled mononuclear cells infiltrating portal tracts in all samples. Statistical evaluation of data showed that the iNOS expression correlated with the HAI and fibrosis. Furthermore a correlation between iNOS and severity of disease was detected (r=0.772, p=0.000).

CONCLUSIONS

Further investigations are required to determine whether iNOS-related treatment protocols could be useful in reducing disease severity.

Mutual changes of thioredoxin and nitrosothiols during biliary cirrhosis: results from humans and cholestatic rats

Cholestasis is associated with changes in NO metabolism and thiol oxidation. Thioredoxin contributes to regulate vascular tone and intracellular redox status by cleaving nitrosothiols and maintaining -SH groups. This study investigated the changes in circulating thioredoxin and nitrosothiols and the relationship with protein sulfhydryls (PSH), hepatic concentrations, hyaluronate, and histology in patients with primary biliary cirrhosis (PBC) and in rats with bile duct ligation (BDL). PSH in erythrocytes were significantly decreased in stage III and IV PBC and at day 10 after BDL. Compared with controls, erythrocyte thioredoxin levels were higher in stage I through III PBC and lower in stage IV patients. Serum thioredoxin levels were significantly higher in PBC stages I and II and lower in stages III and IV. Serum nitrosothiols were higher in all PBC patients and inversely related to thioredoxin and hyaluronate. In rats, serum, hepatic, and mitochondrial thioredoxin had initially increased after BDL (day 1-3) and then decreased. After day 7 BDL, nitrosothiols were 10-fold increased in serum and liver, and even higher in mitochondria. In the liver, thioredoxin was inversely related to both nitrosothiols and PSH. In rats, the difference in time average changes from baseline among serum, hepatic, and erythrocyte thioredoxin suggests that most of circulating thioredoxin originates from the liver.

CONCLUSION

Our findings indicate that cholestasis is associated with significant mutual and interrelated changes between circulating and hepatic thioredoxin and nitrosothiols. The increase of hepatic, mitochondrial, and circulating nitrosothiols with ongoing cholestasis suggests an active participation of NO in both liver injury and extrahepatic changes.

Nitrotyrosine formation and heme oxygenase-1 expression in endotoxemic cirrhotic rats

BACKGROUND

Endotoxemia increases hepatic toxicity and mortality in cirrhosis. Because the mechanism of augmented hepatotoxicity in endotoxemic cirrhotic rats is still unclear, we wanted to investigate whether oxidative and nitrosative stress play a causative role in lipopolysaccharide (LPS)-treated cirrhotic rats.

METHODS

Liver cirrhosis was produced by the administration of thioacetamide (0.3 g/L of tap water) for a period of 3 months in rats. At the end of this period, cirrhotic rats were sacrificed 6 h after LPS injection (5 mg/kg, intraperitoneally). Serum transaminase activities, plasma total nitrite and nitrotyrosine (NT) levels as well as hepatic lipid peroxides, NT formation and heme oxygenase 1 (HO-1) expression were determined.

RESULTS

LPS administration to cirrhotic rats caused further increases in serum transaminase activities, and plasma total nitrite and NT levels as well as hepatic lipid peroxide levels as compared to cirrhotic rats. Hepatic NT formation and HO-1 expression were also found to be increased in LPS-injected cirrhotic rats.

CONCLUSIONS

Our results indicate that increased oxidative and nitrosative stress may have a synergistic effect in LPS-augmented hepatotoxicity in cirrhotic rats.