Levels of the oxidative stress marker γ-glutamyltranspeptidase at different stages of nonalcoholic fatty liver disease

An individual patient data meta-analysis to determine cut-offs for and confounders of NAFLD-fibrosis staging with magnetic resonance elastography

BACKGROUND & AIMS

We conducted an individual patient data meta-analysis to establish stiffness cut-off values for magnetic resonance elastography (MRE) in staging liver fibrosis and to assess potential confounding factors.

METHODS

A systematic review of the literature identified studies reporting MRE data in patients with NAFLD. Data were obtained from the corresponding authors. The pooled diagnostic cut-off value for the various fibrosis stages was determined in a two-stage meta-analysis. Multilevel modelling methods were used to analyse potential confounding factors influencing the diagnostic accuracy of MRE in staging liver fibrosis.

RESULTS

Eight independent cohorts comprising 798 patients were included in the meta-analysis. The area under the receiver operating characteristic curve (AUROC) for MRE in detecting significant fibrosis was 0.92 (sensitivity, 79%; specificity, 89%). For advanced fibrosis, the AUROC was 0.92 (sensitivity, 87%; specificity, 88%). For cirrhosis, the AUROC was 0.94 (sensitivity, 88%, specificity, 89%). Cut-offs were defined to explore concordance between MRE and histopathology: ≥F2, 3.14 kPa (pretest probability, 39.4%); ≥F3, 3.53 kPa (pretest probability, 24.1%); and F4, 4.45 kPa (pretest probability, 8.7%). In generalized linear mixed model analysis, histological steatohepatitis with higher inflammatory activity (odds ratio 2.448, 95% CI 1.180-5.079, p <0.05) and high gamma-glutamyl transferase (GGT) concentration (>120U/L) (odds ratio 3.388, 95% CI 1.577-7.278, p <0.01] were significantly associated with elevated liver stiffness, and thus affecting accuracy in staging early fibrosis (F0-F1). Steatosis, as measured by magnetic resonance imaging proton density fat fraction, and body mass index(BMI) were not confounders.

CONCLUSIONS

MRE has excellent diagnostic performance for significant, advanced fibrosis and cirrhosis in patients with NAFLD. Elevated inflammatory activity and GGT level may lead to overestimation of early liver fibrosis, but anthropometric measures such as BMI or the degree of steatosis do not.

IMPACT AND IMPLICATIONS

This individual patient data meta-analysis of eight international cohorts, including 798 patients, demonstrated that MRE achieves excellent diagnostic accuracy for significant, advanced fibrosis and cirrhosis in patients with NAFLD. Cut-off values (significant fibrosis, 3.14 kPa; advanced fibrosis, 3.53 kPa; and cirrhosis, 4.45 kPa) were established. Elevated inflammatory activity and gamma-glutamyltransferase level may affect the diagnostic accuracy of MRE, leading to overestimation of liver fibrosis in early stages. We observed no impact of diabetes, obesity, or any other metabolic disorder on the diagnostic accuracy of MRE.

Role of Oxidative Stress and Carcinoembryonic Antigen-Related Cell Adhesion Molecule 1 in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) has become a widely studied subject due to its increasing prevalence and links to diseases such as type 2 diabetes and obesity. It has severe complications, including nonalcoholic steatohepatitis, cirrhosis, hepatocellular carcinoma, and portal hypertension that can lead to liver transplantation in some cases. To better prevent and treat this pathology, it is important to understand its underlying physiology. Here, we identify two main factors that play a crucial role in the pathophysiology of NAFLD: oxidative stress and the key role of carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1). We discuss the pathophysiology linking these factors to NAFLD pathophysiology.

IDENTIFICATION OF SUBPHENOTYPES OF SEPSIS-ASSOCIATED LIVER DYSFUNCTION USING CLUSTER ANALYSIS

ABSTRACT

Objectives: We attempted to identify and validate the subphenotypes of sepsis-associated liver dysfunction (SALD) using routine clinical information. Design: This article is a retrospective observational cohort study. Setting: We used the Medical Information Mart for Intensive Care IV database and the eICU Collaborative Research Database. Patients: We included adult patients (age ≥18 years) who developed SALD within the first 48 hours of intensive care unit (ICU) admission. We excluded patients who died or were discharged from the ICU within the first 48 hours of admission. Patients with abnormal liver function before ICU admission were also excluded. Measurements and Main Results: Patients in the MIMIC-IV 1.0 database served as a derivation cohort. Patients in the eICU database were used as validation cohort. We identified four subphenotypes of SALD (subphenotype α, β, γ, δ) using K-means cluster analysis in 5234 patients in derivation cohort. The baseline characteristics and clinical outcomes were compared between the phenotypes using one-way analysis of variance/Kruskal-Wallis test and the χ 2 test. Moreover, we used line charts to illustrate the trend of liver function parameters over 14 days after ICU admission. Subphenotype α (n = 1,055) was the most severe cluster, characterized by shock with multiple organ dysfunction (MODS) group. Subphenotype β (n = 1,179) had the highest median bilirubin level and the highest proportion of patients with underlying liver disease and coexisting coagulopathy (increased bilirubin group). Subphenotype γ (n = 1,661) was the cluster with the highest mean age and had the highest proportion of patients with chronic kidney disease (aged group). Subphenotype δ (n = 1,683) had the lowest 28-day and in-hospital mortality (mild group). The characteristics of clusters in the validation cohort were similar to those in the derivation cohort. In addition, we were surprised to find that GGT levels in subphenotype δ were significantly higher than in other subphenotypes, showing a different pattern from bilirubin. Conclusions: We identified four subphenotypes of SALD that presented with different clinical features and outcomes. These results can provide a valuable reference for understanding the clinical characteristics and associated outcomes to improve the management of patients with SALD in the ICU.

Gamma-Glutamyltransferase Activity (GGT) Is a Long-Sought Biomarker of Redox Status in Blood Circulation: A Retrospective Clinical Study of 44 Types of Human Diseases

Background and Aim. Redox equilibria are critical for life, but the biomarkers of redox status are currently unavailable. Gamma-glutamyltransferase (GGT) is an essential factor for modulating redox equilibrium through glutathione. In clinical practice, increased circulating GGT activity is used as a hepatobiliary disease biomarker. However, increased circulating GGT activities have also been observed in cancers, heart disease, diabetes, hyperuricemia, inflammation, renal insufficiency, and other diseases, explained by its role in maintaining redox equilibrium inside and outside cells. Previous studies on GGT were mainly limited to one type of disease at one time. In the current study, we systematically compared the GGT levels in 44 different human diseases to test if it could serve as a redox status biomarker in blood circulation. Methods. The clinical GGT data from 168,858 patients with 44 diseases and 132,357 healthy control in the clinical laboratory of our hospital over the past five years were retrieved. All data were analyzed with SPSS, RStudio V.1.3.1073, and python libraries 3.8. Results. Thirty-eight out of 44 diseases had significantly increased ( $p<0.001$ ) circulating GGT activities, whereas gastric cancer, anemia, renal cyst, cervical cancer, preeclampsia, and knee-joint degenerative diseases had significantly decreased ( $p<0.001$ ) GGT activities compared to the healthy control. ROC analyses showed that GGT was an excellent biomarker for liver cancer ( $\text{AUC}=0.86$ ), pancreatitis ( $\text{AUC}=0.84$ ), or hepatic encephalopathy ( $\text{AUC}=0.80$ ). All pancreas-related diseases had more than 8-fold increases in GGT activity span than the healthy control, while pancreatic cancer had a 12-fold increase (1021 U/L vs. 82 U/L). The knee-joint degenerative disease had the lowest median and narrowest GGT activity range (63 U/L). Furthermore, most diseases’ lowest to highest GGT activities were beyond the healthy control in both directions. Conclusions. Thirty-eight out of 44 diseases were in overall oxidative states defined by the increased GGT median values. In contrast, knee-joint degenerative disease, gastric cancer, anemia, renal cyst, cervical cancer, and preeclampsia were in overall antioxidative states. Moreover, most diseases swing between oxidative and antioxidative states, evidenced by the increased lowest to highest GGT activity ranges than the healthy control. Liver- and pancreas-related abnormalities were responsible for significantly increased GGT activities. Our overall results suggested that circulating GGT was a redox status biomarker.

Pharmacological systemic analysis of gardenia fructus against non-alcoholic fatty liver disease and validation of animal models

[Purpose]

We aimed to investigate the systemic pharmacological analysis of gardenia fructus (GF) and the proof of concepts. We examined the antioxidant and anti-inflammatory effects in high-fat (HF) diet mice.

[Methods]

The active compounds of GF and the target genes were identified using the Traditional Chinese Medicine Database and Analysis Platform (oral bioavailability ≥ 30%, Caco-2 permeability ≥ -0.4, and drug-likeness ≥ 0.18). The rats were divided into four groups: untreated group, HF group, HF and metformin (17 mg/kg) treated group, and HF and treated with GF (28 mg/kg) for 8 weeks group. Hepatic lesion changes and markers were analyzed using hematoxylin and eosin staining and immunohistochemistry assay.

[Results]

In the systemic analysis, we identified 14 active compounds including A, B, and C. From these 14 compounds, 242 biological target genes were identified. The top 10 Gene Ontology were analyzed using GO-biological process analysis: removal of superoxide radicals, regulation of endothelial cell apoptotic process, and cellular response to lipopolysaccharide. GF extracts in high-fat diet-induced non-alcoholic fatty liver disease (NAFLD) mice models significantly regulated hepatic lesion markers, such as mTOR, 8-Hydroxy-2'-deoxyguanosine as well as oxidative stress activities, TGF-β, and phosphorylation of ERK1/2.

[Conclusion]

These results suggest that GF, as an exercise supplement, can alleviate NAFLD disease or fatty liver inflammation. Further studies are required to verify the synergistic effect of GF treatment combined with exercise, which is known to alleviate NAFLD and fatty liver inflammation.

Association of UCP3 Polymorphisms with Nonalcoholic Steatohepatitis and Metabolic Syndrome in Nonalcoholic Fatty Liver Disease Brazilian Patients

Background: We investigated the possible association of uncoupling protein 3 gene (UCP3) single nucleotide polymorphisms (SNPs) with nonalcoholic steatohepatitis (NASH) and metabolic syndrome (MetS) in nonalcoholic fatty liver disease (NAFLD) Brazilian patients. Methods: UCP3 SNPs rs1726745, rs3781907, and rs11235972 were genotyped in 158 biopsy-proven NAFLD Brazilian patients. Statistics was performed with JMP, R, and SHEsis softwares. Results: The TT genotype of rs1726745 was associated with less occurrence of MetS (P = 0.006) and with lower body mass index (BMI) in the entire NAFLD sample (P = 0.01) and in the NASH group (P = 0.02). The rs1726745-T was associated with lower values of AST (P = 0.001), ALT (P = 0.0002), triglycerides (P = 0.01), and total cholesterol (P = 0.02) in the entire NAFLD sample. Between groups, there were lower values of aminotransferases strictly in individuals with NASH (AST, P = 0.002; ALT, P = 0.0007) and with MetS (AST, P = 0.002; ALT, P = 0.001). The rs3781907-G was associated with lower GGT elevation values in the entire NAFLD sample (P = 0.002), in the NASH group (P = 0.004), and with MetS group (P = 0.003) and with protection for advanced fibrosis (P = 0.01). The rs11235972-A was associated with lower GGT values in the entire NAFLD sample (P = 0.006) and in the NASH group (P = 0.01) and with MetS group (P = 0.005), with fibrosis absence (P = 0.01) and protection for advanced fibrosis (P = 0.01). The TAA haplotype was protective for NASH (P = 0.002), and TGG haplotype was protective for MetS (P = 0.01). Conclusion: UCP3 gene variants were associated with protection against NASH and MetS, in addition to lower values of liver enzymes, lipid profile, BMI and, lesser fibrosis severity in the studied population.

Alanine Aminotransferase and Gamma-Glutamyl Transpeptidase Predict Histologic Improvement in Pediatric Nonalcoholic Steatohepatitis

BACKGROUND AND AIMS

Predictive, noninvasive tools are needed to monitor key features of nonalcoholic fatty liver disease (NAFLD) in children that relate to improvement in liver histology. The purpose of this study was to evaluate the relationship between liver chemistries and liver histology using data from the CyNCh (Cysteamine Bitartrate Delayed-Release for the Treatment of NAFLD in Children) clinical trial.

APPROACH AND RESULTS

This study included 146 children. Improvement in liver histology, defined as decrease in nonalcoholic fatty liver disease (NAFLD) Activity Score ≥2 points without worsening of fibrosis, occurred in 43 participants (30%). There were 46 participants with borderline zone 1 nonalcoholic steatohepatitis (NASH) at baseline, with resolution in 28% (12 of 46). Multivariate models were constructed using baseline and change in alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyl transferase (GGT) at 52 weeks, for improvement in (1) liver histology primary outcome, (2) borderline zone 1 NASH, and (3) fibrosis. For improvement in histology, the model (P < 0.0001) retained baseline and change in GGT (area under the receiver operating characteristic [AUROC], 0.79; 95% confidence interval [CI], 0.71-0.87). For borderline zone 1 NASH, the model (P = 0.0004) retained baseline and change in ALT (AUROC, 0.80; 95% CI, 0.67-0.93). For fibrosis, the model (P < 0.001) retained baseline and change in ALT (AUROC, 0.80; 95% CI, 0.67-0.93). Additional clinical parameters were added to the models using Akaike's information criterion selection, and significantly boosted performance: improvement in histology with AUROC of 0.89 (95% CI, 0.82-0.95), borderline zone 1 NASH with AUROC of 0.91 (95% CI, 0.83-0.99), and fibrosis with AUROC of 0.89 (95% CI, 0.82-0.94). Models were validated using data from the TONIC (Treatment of Nonalcoholic Fatty Liver Disease in Children) trial.

CONCLUSIONS

In children with NAFLD, dynamic changes in serum ALT and GGT are associated with change in liver histology and appear to be powerful indicators of histological response.

Non-alcoholic fatty liver and lipid profile status in patients with melasma: A case-control study

BACKGROUND

There are pieces of evidence regarding the association between melasma and metabolic syndrome. To assess the prevalence and grade of nonalcoholic fatty liver and lipid profile status in patients with melasma, we designed this case-control study.

METHODS

This study was performed on 30 consecutive women with melasma who referred to the dermatology clinic of the hospital as the case group and 34 healthy women. For all participants, serum lipid profiles and liver enzymes were checked. Also, the existence of fatty liver was assessed by ultrasonography.

RESULTS

Except for serum level of LDL (low-density lipoprotein) that was significantly higher in the melasma group than in the healthy group (104.23 ± 25.00 mg/dl versus 89.85 ± 23.00 mg/dl, p = 0.020), the level of other parameters including other lipid profiles, blood sugar, or liver enzymes was similar in both groups. In ultrasonography, the overall prevalence of fatty liver was 23.3% in the melasma group and 20.6% in the control group, and no difference was found between the two groups in grade of fatty liver (p = 0.791).

CONCLUSION

The study showed a higher serum LDL level in patients with melasma compared to women without melasma, but there was no difference between the groups in prevalence or grade of fatty liver.

Oxidative stress and DNA damage in agricultural workers after exposure to pesticides

BACKGROUND

Recent epidemiological studies on workers describe that exposure to pesticides can induce oxidative stress by increased production of free radicals that can accumulate in the cell and damage biological macromolecules, for example, RNA, DNA, DNA repair proteins and other proteins and/or modify antioxidant defense mechanisms, as well as detoxification and scavenger enzymes. This study aimed to assess oxidative stress and DNA damage among workers exposed to pesticides.

METHODS

For this purpose, 52 pesticide exposed workers and 52 organic farmers were enrolled. They were assessed: the pesticide exposure, thiobarbituric acid reactive substances (TBARS), total glutathione (TG), oxidized glutathione levels (GSSG), and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), levels.

RESULTS

Correlation between pesticide exposure was positively associated with high TBARS and 8-oxodG levels (p <  0.001). A negative association was founded with TG and GSSG and pesticide exposure.

CONCLUSIONS

The present investigation results seem to indicate a mild augment in oxidative stress associated with pesticide exposure, followed by an adaptive response to increase the antioxidant defenses to prevent sustained oxidative adverse effects stress.

Oxidative stress and DNA damage in agricultural workers after exposure to pesticides

BACKGROUND

Recent epidemiological studies on workers describe that exposure to pesticides can induce oxidative stress by increased production of free radicals that can accumulate in the cell and damage biological macromolecules, for example, RNA, DNA, DNA repair proteins and other proteins and/or modify antioxidant defense mechanisms, as well as detoxification and scavenger enzymes. This study aimed to assess oxidative stress and DNA damage among workers exposed to pesticides.

METHODS

For this purpose, 52 pesticide exposed workers and 52 organic farmers were enrolled. They were assessed: the pesticide exposure, thiobarbituric acid reactive substances (TBARS), total glutathione (TG), oxidized glutathione levels (GSSG), and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), levels.

RESULTS

Correlation between pesticide exposure was positively associated with high TBARS and 8-oxodG levels (p <  0.001). A negative association was founded with TG and GSSG and pesticide exposure.

CONCLUSIONS

The present investigation results seem to indicate a mild augment in oxidative stress associated with pesticide exposure, followed by an adaptive response to increase the antioxidant defenses to prevent sustained oxidative adverse effects stress.

Factors independently associated with cardiorespiratory fitness in patients with non-alcoholic fatty liver disease

Low cardiorespiratory fitness (CRF) is associated with non-alcoholic fatty liver disease (NAFLD) and low CRF is an important risk factor for cardiovascular disease. The factors that influence CRF in NAFLD are poorly understood and it has been suggested that reduced hepatic mitochondrial function (HMF) may be linked to low CRF. Therefore, our aim was to determine the factors associated with CRF in NAFLD.

METHODS

Ninety-seven patients with NAFLD were studied. CRF was assessed by treadmill testing and expressed as maximal O₂ consumption (VO₂ peak) per lean body mass. HMF was assessed by the ¹³ C-ketoisocaproate breath test. Multivariable linear regression modelling was undertaken to test the independence of associations with CRF.

RESULTS

Mean (SD) age was 51 (13) years and 61% were men. With CRF as the outcome, age (B coefficient -0.3, 95%CI -0.4, -0.2, P < .0001), total body fat mass (B coefficient -0.2, 95%CI -0.3, -0.05, P = .01), type 2 diabetes mellitus (T2DM) (B coefficient -3.6, 95%CI -1.1, -6.1, P = .005), smoking status (B coefficient -5.7, 95%CI -1.9, -9.5, P = .004), serum γ-glutamyl transferase (GGT) (B coefficient -0.04, 95%CI -0.05, -0.02, P < .0001), HMF (B coefficient -0.5, 95%CI -0.8, -0.1, P = .01) and diastolic function (B coefficient 0.1, 95%CI 0.05, 0.13, P < .0001) were independently associated with CRF. This model explained 60% of the total variance in CRF (R²  = 0.6, P < .0001); and this model with GGT alone explained 24% of the variance in CRF.

CONCLUSIONS

In patients with NAFLD, HMF is independently associated with CRF and a model with GGT alone explained most of the variance in CRF.

Poor Adherence to Mediterranean Diet and Serum Lipopolysaccharide are Associated with Oxidative Stress in Patients with Non-Alcoholic Fatty Liver Disease

Oxidative stress plays a pivotal role in non-alcoholic fatty liver disease (NAFLD). Factors inducing oxidative stress in NAFLD may be several; however, a relationship with the adherence to Mediterranean Diet (Med-diet) and with serum lipopolysaccharide (LPS) has been poorly investigated in this setting. The aim was to investigate factors associated with impaired oxidative stress in NAFLD, focusing on the potential role of LPS and Med-diet. We enrolled 238 consecutive outpatients from the PLINIO study, in whom we measured the soluble Nox2-derived peptide (sNox2-dp), a marker of systemic oxidative stress, and serum LPS. Adherence to Med-diet was investigated by a nine-item validated dietary questionnaire. Serum sNox2-dp and LPS were higher in patients with NAFLD compared to those without (25.0 vs. 9.0 pg/mL, p < 0.001 and 62.0 vs. 44.9 pg/mL, p < 0.001, respectively). In patients with NAFLD, the highest sNox2-dp tertile was associated with the top serum LPS tertile (Odds Ratio (OR): 4.71; p < 0.001), APRI > 0.7 (OR: 6.96; p = 0.005) and Med-diet-score > 6 (OR: 0.14; p = 0.026). Analyzing individual foods, the daily consumption of wine (OR: 0.29, p = 0.046) and the adequate weekly consumption of fish (OR: 0.32, p = 0.030) inversely correlated with the top sNox2-dp tertile. In conclusion, patients with NAFLD showed impaired oxidative stress. Levels of sNox2 correlated with serum LPS and with low adherence to Med-Diet.

Nonalcoholic Fatty Liver Disease Pandemic Fuels the Upsurge in Cardiovascular Diseases

Cardiovascular diseases (CVDs) remain a leading cause of death worldwide. Among the major risk factors for CVD, obesity and diabetes mellitus have received considerable attention in terms of public policy and awareness. However, the emerging prevalence of nonalcoholic fatty liver disease (NAFLD), as the most common liver and metabolic disease and a cause of CVD, has been largely overlooked. Currently, the number of individuals with NAFLD is greater than the total number of individuals with diabetes mellitus and obesity. Epidemiological studies have established a strong correlation between NAFLD and an increased risk of CVD and CVD-associated events. Although debate continues over the causal relationship between NAFLD and CVD, many mechanistic and longitudinal studies have indicated that NAFLD is one of the major driving forces for CVD and should be recognized as an independent risk factor for CVD apart from other metabolic disorders. In this review, we summarize the clinical evidence that supports NAFLD as a risk factor for CVD epidemics and discuss major mechanistic insights regarding the acceleration of CVD in the setting of NAFLD. Finally, we address the potential treatments for NAFLD and their potential impact on CVD.

The Effectiveness of Mediterranean Diet in Nonalcoholic Fatty Liver Disease Clinical Course: An Intervention Study

Diet is a modifiable key factor targeted in prevention and management of nonalcoholic fatty liver disease (NAFLD). The aim was to study the effect of Mediterranean Diet (MedDiet) on clinical, biochemical, and inflammatory profile in NAFLD patients with simple steatosis. Potential associations of signal transducer and activator of transcription 3 (STAT3) rs2293152 genotype to diet composition and patients' profile were investigated. In this nonrandomized, open-label, 24-week prospective intervention study, 44 untreated NAFLD patients with nonsignificant fibrosis received nutritional counsel to increase adherence to MedDiet. Adherence to MedDiet was estimated with MedDietScore. Furthermore, we genotyped STAT3 rs2293152 single nucleotide polymorphism and performed clinical and inflammatory measurements. In all patients, MedDietScore increased and anthropometric indices improved, whereas liver imaging, liver fibrosis score, blood pressure, fasting glucose, glycated hemoglobin (HbA1c), C-reactive protein (CRP), visfatin, and oxidized low-density lipoprotein levels were also significantly ameliorated compared with baseline (P < .05). No association of STAT3 polymorphism with diet composition was found. Comparisons of mean differences between G- and C-carriers at the end point of the trial showed that only visfatin was significantly associated with the STAT3 genotype (-0.0 ± 4.6 vs. -4.2 ± 3.9, P = .04, respectively). Carrying the G-allele was associated with an increase of the visfatin levels (3.4 ± 1.5 ng/mL, P = .028). Our results show amelioration of clinical, biochemical, and inflammatory biomarkers in NAFLD patients in response to MedDiet. STAT3 rs2293152 G-carriers experienced more beneficial changes at the end of the intervention compared with baseline. An association between visfatin levels and STAT3 genotype has been shown for the first time.

Crosstalk between nonalcoholic fatty liver disease and cardiometabolic syndrome

Nonalcoholic fatty liver disease (NAFLD) is a chronic condition characterized by fat accumulation combined with low-grade inflammation in the liver. A large body of clinical and experimental data shows that increased flux of free fatty acids from increased visceral adipose tissue and de novo lipogenesis can lead to NAFLD and insulin resistance. Thus, individuals with obesity, insulin resistance, and dyslipidaemia are at the greatest risk of developing NAFLD. Conversely, NAFLD is a phenotype of cardiometabolic syndrome. Notably, researchers have discovered a close association between NAFLD and impaired glucose metabolism and focused on the role of NAFLD in the development of type 2 diabetes. Moreover, recent studies provide substantial evidence for an association between NAFLD and atherosclerosis and cardiometabolic disorders. Even if NAFLD can progress into severe liver disorders including nonalcoholic steatohepatitis (NASH) and cirrhosis, the majority of subjects with NAFLD die from cardiovascular disease eventually. In this review, we propose a potential pathological link between NAFLD/NASH and cardiometabolic syndrome. The potential factors that can play a pivotal role in this link, such as inflammation, insulin resistance, alteration in lipid metabolism, oxidative stress, genetic predisposition, and gut microbiota are discussed.

Tunicamycin-Induced ER Stress is Accompanied with Oxidative Stress via Abrogation of Sulfur Amino Acids Metabolism in the Liver

Endoplasmic reticulum (ER) stress is involved in non-alcoholic fatty liver disease (NAFLD), but the relationship between oxidative stress, another well-known risk factor of NAFLD, and ER stress has yet to be elucidated. In this study, we treated mice with tunicamycin (TM) (2 mg/kg body weight) for 48 h to induce ER stress in the liver and examined the metabolic pathway that synthesizes the endogenous antioxidant, glutathione (GSH). Tunicamycin (TM) treatment significantly increased mRNA levels of CHOP and GRP78, and induced lipid accumulation in the liver. Lipid peroxidation in the liver tissue also increased from TM treatment (CON vs. TM; 3.0 ± 1.8 vs. 11.1 ± 0.8 nmol MDA/g liver, p < 0.001), which reflects an imbalance between the generation of reactive substances and antioxidant capacity. To examine the involvement of GSH synthetic pathway, we determined the metabolomic changes of sulfur amino acids in the liver. TM significantly decreased hepatic S-adenosylmethionine concentration in the methionine cycle. The levels of cysteine in the liver were increased, while taurine concentration was maintained and GSH levels profoundly decreased (CON vs. TM; 8.7 ± 1.5 vs. 5.4 ± 0.9 µmol GSH/g liver, p < 0.001). These results suggest that abnormal cysteine metabolism by TM treatment resulted in a decrease in GSH, followed by an increase in oxidative stress in the liver. In HepG2 cells, decreased GSH levels were examined by TM treatment in a dose dependent manner. Furthermore, pretreatment with TM in HepG2 cells potentiated oxidative cell death, by exacerbating the effects of tert-butyl hydroperoxide. In conclusion, TM-induced ER stress was accompanied by oxidative stress by reducing the GSH synthesis, which made the liver more susceptible to oxidative stress.

Adropin protects against liver injury in nonalcoholic steatohepatitis via the Nrf2 mediated antioxidant capacity

Adropin, a secretory signal peptide, has shown beneficial effects on improving glucose homeostasis and dyslipidemia. However, whether this peptide affects nonalcoholic steatohepatitis (NASH) has remained unclear. In this study, the serum adropin levels, liver injury and oxidative stress were measured in diet-induced NASH mice. Adropin knock-out mice and palmitate treated primary hepatic cells were used to investigate the influence of adropin on liver injury. Our results show that serum adropin levels were decreased and negatively correlated with liver injury in NASH mice. Knockout of adropin significantly exacerbated hepatic steatosis, inflammatory responses and fibrosis in mice after either methionine-choline deficient diet (MCD) or western diet (WD) feeding. And the treatment with adropin bioactive peptides ameliorated NASH progression in mice. Adropin alleviated hepatocyte injury by upregulating the expression of Gclc, Gclm, and Gpx1 in a manner dependent on Nrf2 transcriptional activity and by increasing the glutathione (GSH) levels. And adropin significantly increased CBP expression and promoted its binding with Nrf2, which enhanced Nrf2 transcriptional activity. Furthermore, AAV8-mediated overexpression of hepatic Nrf2 expression functionally restored the liver injury induced by adropin-deficiency MCD-fed mice. These findings provide evidence that adropin activates Nrf2 signaling and plays a protective role in liver injury of NASH and therefore might represent a novel target for the prevention and treatment of NASH.

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The serum adropin levels were lower in the NASH model mice and negatively correlated with oxidative damage and liver injury.

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Mice lacking adropin (Adropin-KO) exhibited more severe liver injury and accelerated NASH progression.

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Treatment with adropin alleviated hepatocyte injury by upregulating CBP/Nrf2 mediated antioxidant activity.

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AAV8-mediated overexpression of hepatic Nrf2 expression ameliorated the NASH progression in Adropin-KO mice.

Biomarkers of oxidative stress in blood of workers exposed to non-cholinesterase inhibiting pesticides

In occupational settings workers are often exposed to pesticides at relatively high doses compared to environmental exposures. Long-term exposure to pesticides has been associated with numerous adverse health effects in epidemiological studies, and oxidative stress is often claimed as one of the underlying mechanisms. In fact, different pesticides have been reported to induce oxidative stress due to the generation of free radicals and/or alteration in antioxidant defense enzymes. The present study examined greenhouse workers regularly exposed to diverse pesticides under integrated production system, and a group of controls of the same geographic area without any chemical exposure. Two different periods of the same crop season were assessed, one of high exposure (with greater use of pesticides) and other of low exposure (in which a less use of these compounds was made). Non-specific biomarkers of oxidative stress, e.g. thiobarbituric acid reactive substances (TBARS), ferric reducing ability of serum (FRAS), total thiol groups (SHT), gamma-glutamyl transpeptidase (GGT) and paraoxonase-1 (PON1) were measured in serum samples from all study subjects, alongside erythrocyte acetylcholinesterase (AChE). Results are suggestive of a mild increase in oxidative stress associated with pesticide exposure, which was compensated by an adaptive response to raise the antioxidant defenses and thus counter the detrimental effects of sustained oxidative stress. This response led to significantly increased levels of FRAS, SHT and PON1 in greenhouse workers relative to controls. Furthermore, AChE was decreased likely as a result of oxidative stress as workers did not use organophosphate insecticides.

The Effects of Physical Exercise on Fatty Liver Disease

The increasing prevalence of obesity has made nonalcoholic fatty liver disease (NAFLD) the most common chronic liver disease. As a consequence, NAFLD and especially its inflammatory form nonalcoholic steatohepatitis (NASH) are the fastest increasing etiology of end-stage liver disease and hepatocellular carcinoma. Physical inactivity is related to the severity of fatty liver disease irrespective of body weight, supporting the hypothesis that increasing physical activity through exercise can improve fatty liver disease. This review summarizes the evidence for the effects of physical exercise on NAFLD and NASH. Several clinical trials have shown that both aerobic and resistance exercise reduce the hepatic fat content. From clinical and basic scientific studies, it is evident that exercise affects fatty liver disease through various pathways. Improved peripheral insulin resistance reduces the excess delivery of free fatty acids and glucose for free fatty acid synthesis to the liver. In the liver, exercise increases fatty acid oxidation, decreases fatty acid synthesis, and prevents mitochondrial and hepatocellular damage through a reduction of the release of damage-associated molecular patterns. In conclusion, physical exercise is a proven therapeutic strategy to improve fatty liver disease.

Chronic dexamethasone exposure markedly decreased the hepatic triglyceride accumulation in growing goats

Chronic stress seriously threatens welfare and health in animals and humans. Consecutive dexamethasone (Dex) injection was used to mimic chronic stress previously. In order to investigate the effect of chronic stress on hepatic lipids metabolism, in this study, 10 healthy male goats were randomly allocated into two groups, one received a consecutive injection of Dex via intramuscularly for 3 weeks (Dex group), the other received the same volume of saline as the control group (Con group). Hepatic health and triglyceride (TG) metabolism were analyzed and compared between two groups. The data showed that a significant decrease of TG in plasma and the liver was significantly decreased by Dex (P < .05), while the hepatic nonesterified fatty acid (NEFA) concentration was increased compared to the Con group (P < .05). Consistent with the decrease of TG level, the activity of hepatic lipoprotein lipase (LPL) and hepatic lipase (HL) enzymes activities were significantly enhanced by Dex. Real-time PCR results showed that the mRNA expression of sterol regulatory element binding transcription factor 1 (SREBP-1), acyl-CoA dehydrogenase long chain (ACADL) and acyl-CoA synthetase bubblegum family member 1 (ACSBG1) genes in liver was significantly up-regulated by chronic Dex injection (P < .05), whereas perilipin 2 (PLIN2) and adipose triglyceride lipase (ATGL) mRNA expression was significantly decreased by Dex (P < .05). In addition, no obvious damages were observed in the liver in both Con and Dex groups demonstrating by the sirius red staining, HE staining as well as several biochemical parameters related to the functional status of hepatocytes. Our data indicate that chronic Dex exposure decreases TG levels in the circulation and the liver through activating lipolysis and inhibiting lipogenesis without causing hepatic damages in the growing goats.

Oxidative Stress as a Critical Factor in Nonalcoholic Fatty Liver Disease Pathogenesis

SIGNIFICANCE

Nonalcoholic fatty liver disease (NAFLD), characterized by liver triacylglycerol build-up, has been growing in the global world in concert with the raised prevalence of cardiometabolic disorders, including obesity, diabetes, and hyperlipemia. Redox imbalance has been suggested to be highly relevant to NAFLD pathogenesis. Recent Advances: As a major health problem, NAFLD progresses to the more severe nonalcoholic steatohepatitis (NASH) condition and predisposes susceptible individuals to liver and cardiovascular disease. Although NAFLD represents the predominant cause of chronic liver disorders, the mechanisms of its development and progression remain incompletely understood, even if various scientific groups ascribed them to the occurrence of insulin resistance, dyslipidemia, inflammation, and apoptosis. Nevertheless, oxidative stress (OxS) more and more appears as the most important pathological event during NAFLD development and the hallmark between simple steatosis and NASH manifestation.

CRITICAL ISSUES

The purpose of this article is to summarize recent developments in the understanding of NAFLD, essentially focusing on OxS as a major pathogenetic mechanism. Various attempts to translate reactive oxygen species (ROS) scavenging by antioxidants into experimental and clinical studies have yielded mostly encouraging results.

FUTURE DIRECTIONS

Although augmented concentrations of ROS and faulty antioxidant defense have been associated to NAFLD and related complications, mechanisms of action and proofs of principle should be highlighted to support the causative role of OxS and to translate its concept into the clinic. Antioxid. Redox Signal. 26, 519-541.

Reduced Glutathione suppresses Oxidative Stress in Nonalcoholic Fatty Liver Disease

Background and aims

Insulin resistance and cytokine production are key mechanisms leading to fatty change in the liver and may produce nonalcoholic steatohepatitis (NASH). Oxidative stress may also contribute to clinical progression from simple fatty liver (FL) to NASH. A therapy for insulin resistance and antioxidant has been applied to treat NASH, yet these treatments are not fully established. In the present study, we have evaluated whether an antioxidant agent, glutathione, prevents the development of NASH from FL.

Materials and methods

Five patients with FL and 10 with NASH were enrolled in the study. Three hundred milligrams per day of glutathione was given orally to patients with nonalcoholic fatty liver disease (NAFLD) every day, and an oxidative stress marker and biochemical tests were analyzed before treatment and 1 and 3 months after starting the treatment. We measured serum levels of 8-hydroxy-2-deoxyguanosine (8-OHdG) and gamma-glutamyltranspeptidase (GGT). Immunohistochemistry for glutathione was performed on formalin fixed liver specimens obtained from liver biopsies.

Results

Before treatment, the NASH group had higher serum 8-OHdG and lower serum glutathione levels than the FL group. Immunohistochemistry revealed that a strong expression of glutathione was observed in zone 3 in both NASH and FL before treatment. Serum levels of alanine transaminase and 8-OHdG were significantly decreased after treatment in the NASH group. Gamma-glutamyltranspeptidase was decreased after treatment, although the decrease was statistically not significant.

Discussion

The present pilot study demonstrated that antioxidant therapy with glutathione may reduce the pathological oxidative stress in the liver in NASH, preventing the progression from NAFLD to NASH.

How to cite this article

Irie M, Sohda T, Anan A, Fukunaga A, Takata K, Tanaka T, Yokoyama K, Morihara D, Takeyama Y, Shakado S, Sakisaka S. Reduced Glutathione suppresses Oxidative Stress in Nonalcoholic Fatty Liver Disease. Euroasian J Hepato-Gastroenterol 2016;6(1):13-18.

The Influence of α-Lipoic Acid and Garlic Administration on Biomarkers of Oxidative Stress and Inflammation in Rabbits Exposed to Oxidized Nutrition Oils

We hypothesized that addition of substances with antioxidant activity could decrease the concentrations of biomarkers of oxidative stress and inflammatory process, thus inhibiting nonalcoholic steatohepatitis development. We investigated the influence of α-lipoic acid (ALA) and garlic administration on the development of adverse changes in rabbit liver and serum under oxidative stress conditions induced with HFD from oxidized oils. We determined 8-hydroxy-2′-deoxyguanosine (8OHdG) and malondialdehyde (MDA) in liver homogenates, total oxidant status (TOS), lipid peroxides (LOO) and tumor necrosis factor alpha (TNFα) in blood serum, and TNFα and IL-1α genes expression in liver. The results indicate that the intake of dietary ALA and garlic was significantly associated with decreases of 8OHdG and MDA levels in rabbits' liver tissue as well as TOS and LOO levels in rabbits' serum. Similarly, TNFα and IL-1α gene expressions were suppressed due to ALA and garlic supplementation. The histopathological analysis confirmed that HFD results in liver disorder leading to steatosis. This adverse effect of HFD was ameliorated by the supplementation of ALA and garlic. The obtained results indicate a beneficial effect of ALA and garlic administration by reducing the oxidative stress intensity and the levels of some proinflammatory cytokines in rabbits fed HFD.

Alleviation mechanisms against hepatocyte oxidative stress in patients with chronic hepatic disorders

AIM

Autophagy induction and Mallory-Denk body (MDB) formation have been considered to have cytoprotective effects from cellular stress in liver diseases. We investigated the relations among oxidative stress, autophagy and MDB formation in patients with chronic hepatitis B (CHB), chronic hepatitis C (CHC) and non-alcoholic fatty liver disease (NAFLD) to clarify the alleviation mechanisms against oxidative stress of hepatocytes.

METHODS

First, we treated cultured cells with proteasome inhibitor (PI) or free fatty acid (FFA) and evaluated endoplasmic reticulum (ER) stress, oxidative stress, ubiquitinated proteins and p62 by western blotting. Then, we used human liver biopsy samples to evaluate oxidative stress, autophagy and MDB formation by immunohistochemical analysis.

RESULTS

Treatment with PI or FFA increased ER stress, oxidative stress, ubiquitinated proteins and p62 in cultured cells. Human liver biopsy samples of CHC and NAFLD showed that MDB formed in areas with strong oxidative stress and that the MDB-containing cells circumvented oxidative stress. Keratin 8 (K8) expression was strong in MDB-containing cells in CHC and NAFLD. However, in CHB samples, the expression of K8 was not increased in response to oxidative stress and MDB aggregates did not appear. Aminotransferase values were significantly lower in patients with CHC and NAFLD in whom light chain 3 antibody expression was increased in response to oxidative stress.

CONCLUSION

Strong expression of K8 was considered to be important for MDB formation. MDB protect liver cells from oxidative stress at a cellular level and autophagy reduced hepatic damage when it was induced in the hepatocytes exposed to strong oxidative stress.

Impact of the superoxide dismutase 2 Val16Ala polymorphism on the relationship between valproic acid exposure and elevation of γ-glutamyltransferase in patients with epilepsy: a population pharmacokinetic-pharmacodynamic analysis

BACKGROUND

There has been accumulating evidence that there are associations among γ-glutamyltransferase (γ-GT) elevation and all-cause mortality, cardiovascular diseases and metabolic diseases, including nonalcoholic fatty liver disease. The primary objective of this study was to evaluate the impact of the most common and potentially functional polymorphisms of antioxidant enzyme genes, i.e. superoxide dismutase 2 (SOD2), glutathione S-transferase M1 and glutathione S-transferase T1, on the γ-GT elevation during valproic acid (VPA) therapy.

METHODS AND FINDINGS

This retrospective study included 237 and 169 VPA-treated Japanese patients with epilepsy for population pharmacokinetic and pharmacokinetic-pharmacodynamic analyses, respectively. A nonlinear mixed-effect model represented the pharmacokinetics of VPA and the relationships between VPA exposure and γ-GT elevation. A one-compartment model of the pharmacokinetic parameters of VPA adequately described the data; while the model for the probability of the γ-GT elevation was fitted using a logistic regression model, in which the logit function of the probability was a linear function of VPA exposure. The SOD2 Val16Ala polymorphism and complication with intellectual disability were found to be significant covariates influencing the intercept of the logit function for the probability of an elevated γ-GT level. The predicted mean percentages of the subjects with γ-GT elevation were about 2- to 3-fold, 3- to 4-fold and 4- to 8-fold greater in patients with the SOD2 Val/Val genotype but without any intellectual disability, those with the SOD2 Val/Ala or Ala/Ala genotype and intellectual disability and those with the SOD2 Val/Val genotype and intellectual disability, respectively, compared to those with the SOD2 Val/Ala or Ala/Ala genotype without intellectual disability.

CONCLUSION

Our results showed that the SOD2 Val16Ala polymorphism has an impact on the relationship between VPA exposure and γ-GT elevation in patients with epilepsy. These results suggest that determining the SOD2 genotype could be helpful for preventing the VPA-induced γ-GT elevation.

Extracellular matrix and liver disease

SIGNIFICANCE

The extracellular matrix (ECM) is a dynamic microenvironment that undergoes continuous remodeling, particularly during injury and wound healing. Chronic liver injury of many different etiologies such as viral hepatitis, alcohol abuse, drug-induced liver injury, obesity and insulin resistance, metabolic disorders, and autoimmune disease is characterized by excessive deposition of ECM proteins in response to persistent liver damage.

CRITICAL ISSUES

This review describes the main collagenous and noncollagenous components from the ECM that play a significant role in pathological matrix deposition during liver disease. We define how increased myofibroblasts (MF) from different origins are at the forefront of liver fibrosis and how liver cell-specific regulation of the complex scarring process occurs.

RECENT ADVANCES

Particular attention is paid to the role of cytokines, growth factors, reactive oxygen species, and newly identified matricellular proteins in the regulation of fibrillar type I collagen, a field to which our laboratory has significantly contributed over the years. We compile data from recent literature on the potential mechanisms driving fibrosis resolution such as MF' apoptosis, senescence, and reversal to quiescence.

FUTURE DIRECTIONS

We conclude with a brief description of how epigenetics, an evolving field, can regulate the behavior of MF and of how new "omics" tools may advance our understanding of the mechanisms by which the fibrogenic response to liver injury occurs.

Gamma-glutamyl transpeptidase level associated with metabolic syndrome and proinflammatory parameters in the young Roma population in eastern Slovakia: a population-based study

BACKGROUND

Elevated gamma-glutamyl transpeptidase (GGT) is present approximately in half of all patients with non-alcoholic fatty liver disease (NAFLD). NAFLD is the liver manifestation of metabolic syndrome (MS). This study aimed to explore the relationship between GGT and MS or proinflammatory parameters.

METHODS

Data from the cross-sectional HepaMeta study conducted in Slovakia in 2011 among Roma living in rural communities were used. Participants (n = 446) were divided into 2 groups; those with elevated GGT and those with normal GGT levels. MS was diagnosed according to the International Diabetes Federation criteria; presence of central obesity and low density lipoproteins (LDL) or high density lipoproteins (HDL), high triglycerides, hypertension, glucose intolerance or type 2 diabetes. Participants were tested for the presence of MS and its components, and biochemical tests for lipid levels (total cholesterol, HDL, LDL, TG) and inflammatory parameters (high sensitivity C-reactive protein--hs-CRP and ferritin) were performed.

RESULTS

Of 446 Roma participants, only 29 (6.5%) had GGT levels above the normal value. After exclusion of patients with viral hepatitis and alcohol abuse, patients with elevated GGT suffered from MS more often (p < 0.001), and patients with more MS components had a higher risk of elevated GGT. We found a significant association between GGT and the individual MS components, except HDL (waist circumference > or = 94 cm in men or 80 cm in women: p < 0.01; BMI > 30: p < 0.001; fasting glucose > or = 5.6 mmol/l: p < 0.001; arterial hypertension: p < 0.05, and TAG > or = 1.7 mmol/l: p < 0.001). Patients with elevated GGT levels had also significantly higher hs-CRP (hs-CRP > 2 mg/l: p < 0.001; hs-CRP > 3 mg/l: p < 0.001) and ferritin (ferritin > 300 mg/l: p < 0.01) levels.

CONCLUSION

Patients with MS have more significantly elevated levels of GGT. There is a significant association of GGT with individual MS components, except HDL and inflammatory parameters (hs-CRP, ferritin).

Modern approach to the clinical management of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common and emerging form of chronic liver disease worldwide. It includes a wide spectrum of liver diseases ranging from simple fatty liver to steatohepatitis, which may progress to cirrhosis, liver cancer, and liver mortality. Common metabolic diseases, which are well established cardiovascular risk factors, have been associated to NAFLD and cardiovascular disease is the single most important cause of morbidity and mortality in this patient population. The pathogenesis of NAFLD appears multifactorial and many mechanisms have been proposed as possible causes of fatty liver infiltration. Management of fatty liver has become a major challenge to healthcare systems as the consequence of the increasing rates of obesity worldwide. First-line management focuses on lifestyle modifications. Moderate weight reduction either by dietary restriction or by increased habitual physical activity is safe and highly recommended. Several therapeutic interventions have been proposed. These include insulin sensitizer agents, lipid lowering drugs, antioxidants such as vitamin E and supplementation of vitamin D₃. However, therapeutic strategies have been largely empirical so far, and experimental trials have mostly been carried out in uncontrolled settings with small sample sizes. Metabolic conditions such as diabetes mellitus, obesity, hypertension and hyperlipidemia, should be strongly considered and a multidisciplinary approach should be personalized for individual patients. Treatment of co-morbidities should be regarded as of paramount importance in the management of these patients. The purpose of this review is to examine different approaches for the clinical management of non-alcoholic fatty liver disease.

The association of insomnia with gastroesophageal reflux symptoms in biopsy-proven nonalcoholic fatty liver disease

BACKGROUND

It is suggested that nonalcoholic fatty liver disease (NAFLD), including nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH), can be associated with insomnia and gastro-esophageal reflux disease (GERD). The relationship between GERD and insomnia in subjects with biopsy-proven NAFLD was investigated.

METHODS

This study enrolled 123 patients with biopsy-proven NAFLD. Insomnia was assessed by the Athens Insomnia Scale (AIS), a self-assessment psychometric instrument designed to quantify sleep difficulty based on ICD-10 criteria; AIS scores ≥ 6 were considered positive for insomnia. GERD symptoms were evaluated using a frequency scale for the symptoms of GERD (FSSG); FSSG scores ≥ 8 were considered positive. Logistic regression models were used to evaluate the association of insomnia with GERD, after adjusting for potential confounders. Thirteen patients with GERD were treated with the proton pump inhibitor rabeprazole (RPZ; 10 mg/day), for 12 weeks.

RESULTS

Of the 123 patients, 76 (62%) were female and 87 (71%) were obese, with 34 (28%) having AIS scores ≥ 6 and 31 (25%) having FSSG scores ≥ 8. Liver biopsy revealed that 40 patients (33%) had NAFL and 83 (67%) had NASH. FSSG and AIS scores were similar in the two groups. HOMA-IR, FSSG scores and γGT (GGT) concentrations were significantly higher in insomniacs than in non-insomniacs. Logistic regression analysis demonstrated that FSSG score and GGT concentration were independently associated with insomnia. RPZ treatment resulted in significantly reductions in both AIS and FSSG scores.

CONCLUSIONS

Nearly 30% of patients with biopsy-proven NAFLD had insomnia, which was related to GGT and GERD and could be relieved by RPZ treatment.

Assessment of acute oral and dermal toxicity of 2 ethyl-carbamates with activity against Rhipicephalus microplus in rats

The acute oral and dermal toxicity of two new ethyl-carbamates (ethyl-4-bromophenyl-carbamate and ethyl-4-chlorophenyl-carbamate) with ixodicide activity was determined in rats. The oral LD50 of each carbamate was 300 to 2000 mg/kg, and the dermal LD50 of each carbamate was >5000 mg/kg. Clinically, the surviving rats that had received oral doses of each carbamate showed decreased weight gain (P < 0.05) and had slight nervous system manifestations. These clinical signs were evident from the 300 mg/kg dose and were reversible, whereas the 2000 mg/kg dose caused severe damage and either caused their death or was motive for euthanasia. At necropsy, these rats had dilated stomachs and cecums with diffuse congestion, as well as moderate congestion of the liver. Histologically, the liver showed slight degenerative lesions, binucleated hepatocytes, focal coagulative necrosis, and congestion areas; the severity of the lesions increased with dosage. Furthermore, an slight increase in gamma-glutamyltransferase, lactate dehydrogenase, and creatinine was observed in the plasma. The dermal application of the maximum dose (5000 mg/kg) of each carbamate did not cause clinical manifestations or liver and skin alterations. This finding demonstrates that the carbamates under study have a low oral hazard and low acute dermal toxicity.

NOX2-generated oxidative stress is associated with severity of ultrasound liver steatosis in patients with non-alcoholic fatty liver disease

Background

Chronic oxidative stress is one of the key mechanisms responsible for disease progression in non-alcoholic fatty liver disease. However, so far, few studies reported increased circulating levels of oxidative stress markers in patients with non-alcoholic fatty liver and no study has been performed with newer markers of systemic oxidative stress. The aim was to assess the relationship between urinary 8-iso-prostaglandin F2α and serum soluble NOX2-derived peptide and the severity of liver steatosis in subjects with non-alcoholic fatty liver.

Methods

The study was performed in 264 consecutive patients referred for suspected metabolic disease. Steatosis was defined according to Hamaguchi ultrasonographic criteria. Oxidative stress was assessed by urinary 8-iso- prostaglandin F2α and serum soluble NOX2-derived peptide levels.

Results

Patients with non-alcoholic fatty liver had higher (p < 0.001) mean values of urinary 8-iso-PGF2α and of serum soluble NOX2-derived peptide, alanine aminotransferase, Cytokeratin-18 and homeostasis model of insulin resistance and lower values of serum adiponectin as compared to those without. Prevalence of metabolic syndrome and of its clinical features was significantly higher in patients with non-alcoholic fatty liver. Same findings were also observed after the exclusion of obese subjects, or subjects with diabetes or with metabolic syndrome and in those not taking statin medication. In addition, the levels of urinary 8-iso-PGF2α were independent predictors of non-alcoholic fatty liver and a strong association of urinary 8-iso-PGF2α and of serum soluble NOX2-derived peptide with the severity of steatosis at ultrasound was also observed.

Conclusions

We demonstrated increased markers of oxidative stress in subjects with non-alcoholic fatty liver. Urinary 8-iso-PGF2α and serum soluble NOX2-derived peptide levels were independent from obesity, diabetes and metabolic syndrome and increased with the severity of liver steatosis at ultrasound.

Subchronic toxicity study in rats of two new ethyl-carbamates with ixodicidal activity

Female and male Wistar rats were used to determine the subchronic oral toxicities of two new ethyl-carbamates with ixodicidal activities (ethyl-4-bromphenyl-carbamate and ethyl-4-chlorphenyl-carbamate). The evaluated carbamates were administered in the drinking water (12.5, 25 and 50 mg/kg/day) for 90 days. Exposure to the evaluated carbamates did not cause mortality or clinical signs and did not affect food consumption or weight gain. However, exposure to these carbamates produced alterations in water consumption, hematocrit, percentages of reticulocytes, plasma proteins, some biochemical parameters (aspartate aminotransferase, gamma-glutamyl transpeptidase, cholinesterase, and creatinine activities), thiobarbituric acid reactive substances, and the relative weight of the spleen. Histologically, slight pathological alterations were found in the liver that were consistent with the observed biochemical alterations. The nonobserved adverse effect levels (NOAELs) of the evaluated carbamates were 12.5 mg/kg/day for both the female and male rats. The low severity and reversibility of the majority of the observed alterations suggest that the evaluated carbamates have low subchronic toxicity.

Antioxidant properties of proanthocyanidins attenuate carbon tetrachloride (CCl4)-induced steatosis and liver injury in rats via CYP2E1 regulation

Liver steatosis is characterized by lipid dysregulation and fat accumulation in the liver and can lead to oxidative stress in liver. Since proanthocyanidins are present in plant-based foods and have powerful antioxidant properties, we investigated whether proanthocyanidins can prevent oxidative stress and subsequent liver injury. Carbon tetrachloride (CCl4) treatment can cause steatosis in rats that models both alcoholic and non-alcoholic fatty liver disease in humans. We pre-treated rats by oral administration of proanthocyanidins extracted from grape seeds 7 days prior to intragastrically administering CCl4. Proanthocyanidin treatment continued for an additional 2 weeks, after which time liver and serum were harvested, and mediators of liver injury, oxidative stress, and histological features were evaluated. CCl4-treated rats exhibited significant increases in the following parameters as compared to non-treated rats: fat droplets in the liver, liver injury (ALT, AST), and DNA damage (8-OHdG). Additionally, CCl4 treatment decreased antioxidant enzymes SOD, GSH, GPX, and CAT in the liver due to their rapid depletion after battling against oxidative stress. Compared to CCl4-treated rats, treatment with proanthocyanidins effectively suppressed lipid accumulation, liver injury, DNA damage, as well as restored antioxidant enzyme levels. Further investigation revealed that proanthocyanidins treatment also inhibited expression of CYP2E1 in liver, which prevented the initial step of generating free radicals from CCl4. The data presented here show that treatment with orally administered proanthocyanidins prevented liver injury in the CCl4-induced steatosis model, likely through exerting antioxidant actions to suppress oxidative stress and inhibiting the free radical-generating CYP2E1 enzyme.

Hepatic glucose uptake is increased in association with elevated serum γ-glutamyl transpeptidase and triglyceride

BACKGROUND

Subjects with fatty liver disease (FLD) can show increased hepatic 2-deoxy-2-((18)F)fluoro-D-glucose (FDG) uptake, but the role of hepatic inflammation has not been explored.

AIMS

We investigated whether hepatic inflammatory response, as implicated by elevated serum markers, is associated with increased liver FDG uptake in FLD.

METHODS

Liver sonography and FDG positron emission tomography was performed in 331 asymptomatic men with nonalcoholic FLD (NAFLD), 122 with alcoholic FLD (AFLD), and 349 controls. Mean standard uptake value (SUV) of liver FDG uptake was compared to cardiac risk factors and serum markers of liver injury.

RESULTS

Hepatic FDG mean SUV was increased in NAFLD (2.40 ± 0.25) and AFLD groups (2.44 ± 0.25) compared to controls (2.28 ± 0.26; both P < 0.001). Both FLD groups also had higher serum γ-glutamylranspeptidase (GGT), triglyceride (TG), hepatic transaminases, and LDL. High GGT and TG levels were independent determinants of increased FDG uptake for both FLD groups. Hepatic mean SUV significantly increased with high compared to low GGT for NAFLD (2.48 ± 0.28 vs. 2.37 ± 0.24), AFLD (2.51 ± 0.27 vs. 2.39 ± 0.23), and control groups (2.39 ± 0.22 vs. 2.26 ± 0.26). High TG increased hepatic mean SUV in AFLD and control groups. Furthermore, serum GGT and TG levels significantly correlated to hepatic mean SUV in all three groups.

CONCLUSIONS

Hepatic FDG uptake is closely associated with elevated TG and GGT regardless of the presence of FLD. Thus, inflammation response may play a major role in increased hepatic glucose uptake.

Hepatic function and the cardiometabolic syndrome

Despite skeletal muscle being considered by many as the source of insulin resistance, physiology tells us that the liver is a central and cardinal regulator of glucose homeostasis. This is sometimes underestimated because, in contrast with muscle, investigations of liver function are technically very difficult. Nevertheless, recent experimental and clinical research has demonstrated clearly that, due in part to its anatomic position, the liver is exquisitely sensitive to insulin and other hormonal and neural factors, either by direct intrahepatic mechanisms or indirectly by organ cross-talk with muscle or adipose tissue. Because the liver receives absorbed nutrients, these have a direct impact on liver function, whether via a caloric excess or via the nature of food components (eg, fructose, many lipids, and trans fatty acids). An emerging observation with a possibly great future is the increase in intestinal permeability observed as a consequence of high fat intake or bacterial modifications in microbiota, whereby substances normally not crossing the gut gain access to the liver, where inflammation, oxidative stress, and lipid accumulation leads to fatty liver, a situation observed very early in the development of diabetes. The visceral adipose tissue located nearby is another main source of inflammatory substances and oxidative stress, and also acts on hepatocytes and Kupffer cells, resulting in stimulation of macrophages. Liberation of these substances, in particular triglycerides and inflammation factors, into the circulation leads to ectopic fat deposition and vascular damage. Therefore, the liver is directly involved in the development of the prediabetic cardiometabolic syndrome. Treatments are mainly metformin, and possibly statins and vitamin D. A very promising avenue is treatment of the leaky gut, which appears increasingly to be an important causal factor in hepatic insulin resistance and steatosis.

Individual and joint impacts of ethanol use, BMI, age and gender on serum gamma-glutamyltransferase levels in healthy volunteers

Excessive ethanol consumption, obesity and increasing age may all lead to increased serum levels of gamma-glutamyltransferase (GGT) enzyme, which plays a key role in the metabolism of extracellular reduced glutathione. However, as yet, the interactions between the various modulators of GGT activities have remained poorly defined. We analyzed data from 15,617 apparently healthy individuals (7254 men and 8363 women, mean age 46 ± 13 years, range 25–74 years) who participated in a national cross-sectional health survey in Finland between 1997 and 2007. All subjects underwent detailed clinical examinations and interviews, including the amount of ethanol use and smoking habits. GGT levels were measured from all participants, and the individual and joint impacts of the different study variables on GGT levels were assessed. Significant individual effects were noted for ethanol use (p < 0.001), body mass index (BMI) (p < 0.001), age (p < 0.001) and smoking (p < 0.001). In men, significant two-factor interactions occurred between ethanol use and age (p < 0.020). Among those over 40 years of age, ethanol consumption was found to be a stronger determinant of increased GGT levels than in men below 40 years, whereas in the latter age group, BMI was found to predominate. In women, a significant two-factor interaction occurred between ethanol and BMI (p = 0.010), whereas it did not with ethanol use and age. The data underscores the role of ethanol consumption and age as major determinants of increased GGT levels in men, whereas in women, a relatively stronger impact was noted for ethanol intake and BMI. In light of the ability of GGT enzyme to modulate crucial redox-sensitive functions, the present findings also support the use of GGT as a biomarker of oxidative stress.

The Serum Gamma Glutamyl Transpeptidase - A Non invasive Diagnostic Bio Marker of Chronic Anicteric Non Alcoholic Liver Diseases

BACKGROUND

The serum gamma glutamyl transpeptidase (GGT) levels rise and return to normal levels later in the chronic anicteric non alcoholic liver diseases than the transaminases levels. So, the estimation of GGT is of some value in monitoring the progress of acute to chronic hepatitis, when the values persist in high levels.

AIMS AND OBJECTIVES

To evaluate the serum GGT levels in patients with chronic anicteric non alcoholic liver diseases and to show that it can be used as a noninvasive diagnostic biomarker for the diagnosis of chronic anicteric non alcoholic liver disorders.

MATERIALS AND METHODS

This was a case control study, in which 50 cases and 50 controls were selected.The liver function tests with a special reference to the serum level of GGT were measured in the laboratory for both the cases and the controls and the serum GGT levels of the cases were compared with those of the controls. The Chi-square and the Fisher exact tests were used to find the significance of the proportions of the study parameters between the cases and the controls. The Student's t test (two tailed) was used to find the significance mean pattern of the study parameters between the cases and the controls.

RESULTS

The mean serum GGT level was 38.73±11 IU/L in the cases and in the controls, it was 20.42±9 IU/L(p<0.001).The mean value of serum ALT was 41.37±12.5 vs 16.3±8iu/l(p<0.001), that of AST was 28.14±8 vs 17.56±8.5iu/l(p<0.05), that of total bilirubin was 0.9±0.3 vs 0.5±0.2mg/dl and that of serum albumin was 4.17±0.6 vs 4.5±0.75gm/dl, as were seen in the cases and the controls respectively.

CONCLUSION

The serum gamma glutamyl transpeptidase level was elevated more consistently along with the alanine transaminase level in all types of anicteric nonalcoholic chronic liver diseases. The alanine transminase level has already been proved to be a marker in the diagnosis of chronic anicteric nonalcoholic liver diseases. So, in view of the persistent elevation, along with the high sensitivity, the elevated gamma glutamyl transpeptidase level can also be used as a noninvasive bio marker of chronic anicteric nonalcoholic liver diseases for both diagnostic and therapeutic purposes.