Increased Serum Alanine Aminotransferase Activity Research Articles

Urinary metabolites of volatile organic compounds and polycyclic aromatic hydrocarbons increases the risk of nonalcoholic fatty liver disease in Korean adolescents: A Korean National Environmental Health Survey (KoNEHS) 2015-2017 analysis

Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases in adolescents and is an urgent public health issue. Several animal studies have suggested that volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs) led to NAFLD. However, few epidemiological studies have confirmed the associations of VOCs and PAHs with NAFLD in the general adolescent population. Therefore, we analyzed 798 adolescents from the Korean National Environmental Health Survey (KoNEHS) 2015-2017 to examine the associations of urinary metabolites for VOCs and PAHs with serum alanine aminotransferase (ALT) activity and NAFLD prevalence. We employed linear, logistic regression, and Bayesian kernel machine regression (BKMR) to evaluate the association of urinary VOCs and PAHs metabolites with ALT activity and NAFLD. After adjusting for all covariates, urinary benzylmercapturic acid level and 2-hydroxyfluorene level increased serum ALT activity and NAFLD prevalence. Additionally, the BKMR analyses showed a significantly positive overall effect on ALT activity and NAFLD prevalence with urinary concentrations of VOCs and PAHs metabolites, and 2-hydroxyfluorene contributed the most. Our study suggests that exposure to low-level VOCs and PAHs may have a detrimental effect on NAFLD risk in adolescents. Given the increasing prevalence of NAFLD in adolescents, future cohort studies are warranted to understand these chemicals’ impact on NAFLD risk. Keywords: volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), adolescents, Non-alcoholic fatty liver disease, Korean National Environmental Health Survey (KoNEHS)

Dietary L-Carnitine Alleviates the Adverse Effects Caused by Reducing Protein and Increasing Fat Contents in Diet Juvenile Largemouth Bass (Micropterus salmoides)

Protein ingredients for formulation of fish feeds are expensive and have limited availability. Therefore, reducing dietary protein while increasing dietary fat content is a common practice in rearing carnivorous fish species. However, the ability of dietary L-carnitine to alleviate adverse effects in such diets is currently unknown. This study investigated the role of L-carnitine supplementation in alleviating adverse effects on growth performance, energy metabolism, antioxidant capacity, and inflammation response in juvenile largemouth bass (Micropterus salmoides) fed on a low protein and high fat diet. Three diets were formulated to contain low protein and high fat (LPHF: 420 g kg-1 protein and 150 g kg-1 lipid), LPHF supplemented with L-carnitine (LPHFC: 420 g kg-1 protein and 150 g kg-1 lipid), and a control diet (CON: 480 g kg-1 protein and 130 g kg-1 lipid). The diets were fed to 30 largemouth bass ( 10.75 ± 0.01 g) juveniles in triplicates for eight weeks. The results showed that the fish feed on LPHF diet increased hepatosomatic index, visceral somatic index, mesenteric fat index, whole-body crude fat content, serum and liver triglyceride concentrations, and serum non-esterified fatty acid level than those fed on CON diet. Moreover, the fish fed on LPHF diet increased serum alanine aminotransferase activity and liver malondialdehyde content and reduced superoxide dismutase (SOD) activities in the serum and liver. Furthermore, the fish fed on LPHF diet reduced the whole-body crude protein content. Interestingly, feeding the fish on the LPHFC diet decreased fat deposition and liver damage by downregulating the expression of genes related to lipogenesis, inflammation, and increased SOD activity. This study indicates that L-carnitine supplementation in largemouth bass alleviates the adverse effects caused by LPHF diet by decreasing lipogenesis and increasing lipid catabolism. Our study provides novel knowledge on strategies to improve utilization of LPHF diet in cultured aquatic animals.

Intestinal farnesoid X receptor mediates the effect of dietary berberine on lipid accumulation in grass carp (Ctenopharyngodon idella)

Berberine (BBR) suppresses lipid accumulation in fish, but mechanisms underlying this effect remain poorly understood. The aim of this study was to test the hypothesis that intestinal farnesoid X receptor (FXR) signaling is involved in this physiological process. Thus, juvenile grass carp (9.90 ± 0.07 g) were fed experimental diets (control, 0.1% BBR, and 0.1% BBR + Gly-β-MCA [an intestine-specific FXR inhibitor]) for 8 weeks. Dietary BBR significantly reduced intraperitoneal fat, hepatic triglyceride (TG), total cholesterol (TC), and whole-body lipid levels, whereas additional supplementation with Gly-β-MCA restored these levels. Dietary BBR also significantly reduced serum TG and high-density lipoprotein cholesterol (HDL-c), and additional supplementation with Gly-β-MCA significantly increased serum alanine aminotransferase activity and levels of TG, TC, HDL-c, and low-density lipoprotein cholesterol. Dietary BBR significantly increased FXR mRNA and protein expression, as well as fibroblast growth factor 19 mRNA expression in the intestine, whereas additional supplementation with Gly-β-MCA reversed these trends. Gly-β-MCA also restored BBR-reduced hepatopancreatic cholesterol 7 alpha-hydroxylase, sterol 12α-hydroxylase, and sterol 27-hydroxylase expression, sterol-regulatory element binding proteins-1c and fatty acid synthase expression, and attenuated BBR-increased peroxisome proliferator activated receptor α, adipose triglyceride lipase, and carnitine palmitoyltransferase 1 expression. Both BBR and BBR + Gly-β-MCA diets significantly reduced the richness and diversity of the fish gut microbiota. The abundance of Firmicutes showed a significant negative correlation with the mRNA expression of FXR in the intestine. Overall, these findings indicate that FXR signaling is involved in lipid suppression induced by dietary BBR in grass carp.

Evaluation of the Effects of Agro Pesticides Use on Liver and Kidney Function in Farmers from Buea, Cameroon.

Agro pesticides are increasingly used worldwide to increase crop production. However, health hazards resulting from human exposure to these chemicals, especially from agricultural areas of developing countries have been a growing concern. The objective of this study was to evaluate the impact of occupational exposure to agro pesticides on the health of farmers in the Buea subdivision, which is one of the major agrarian areas in Cameroon. The study was transversal and involved 90 participants including 58 farmers using pesticides and a reference population of 32 men not involved in occupational use of agro pesticides. The participants were interviewed on agro pesticide use and their health status. Thereafter, blood samples were collected from the participants and used for the assessment of biochemical markers of the liver (alanine aminotransferase and aspartate aminotransferase) and the kidney (creatinine and uric acid) function. Results revealed that farmers frequently used insecticides, fungicides, and herbicides in their farming activities. Farmers reported several acute health symptoms related to pesticides use with the common ones being skin rash, eye irritation, and face burn. When compared to the reference population, the farmers showed significantly elevated (p < 0.01) alanine aminotransferase activity. However, other parameters investigated were not affected significantly. These results suggested that farmers were exposed to 3 different classes of agro pesticides, which induced eye and skin affections. Pesticides exposure resulted in alterations of the liver function hence the increased serum alanine aminotransferase activity. Therefore, there is a need to sensitize the farmers on toxicity and liver alteration potential of agro pesticides and the importance of appropriate protective equipment that may minimize exposure.

Adenovirus‑mediated overexpression of bone morphogenetic protein‑9 promotes methionine choline deficiency‑induced non‑alcoholic steatohepatitis in non‑obese mice

Liver inflammation and macrophage infiltration are critical steps in the progression of non-alcoholic fatty liver to the development of non-alcoholic steatohepatitis. Bone morphogenetic protein-9 is a cytokine involved in the regulation of chemokines and lipogenesis. However, the function of bone morphogenetic protein-9 in non-alcoholic steatohepatitis is still unknown. The present study hypothesized that bone morphogenetic protein-9 may contribute to steatohepatitis in mice fed a methionine choline deficiency diet (MCD). C57BL/6 mice overexpressing bone morphogenetic protein-9 and control mice were fed the MCD diet for 4 weeks. Liver tissue and serum samples were obtained for subsequent measurements. Bone morphogenetic protein-9 overexpression exacerbated steatohepatitis in mice on the MCD diet, as indicated by liver histopathology, increased serum alanine aminotransferase activity, aspartate transaminase activity, hepatic inflammatory gene expression and M1 macrophage recruitment. Although bone morphogenetic protein-9 overexpression did not affect the expression of pro-fibrogenic genes, including Collagen I (α)1 or matrix metalloproteinase (MMP) 9, it did upregulate the expression of transforming growth factor-β and plasminogen activator inhibitor 1, and downregulated the expression of MMP2. The above results indicate that bone morphogenetic protein-9 exerts a pro-inflammatory role in MCD diet-induced non-alcoholic steatohepatitis.

Effect of Lycosome-Formulated Phosphatidylcholine on Parameters of Biological Oxidation after Single Intake of Moderate Amount of Alcohol.

Ingestion of a single dose of alcohol, ranging from the intake of a moderate amount alcohol to binge drinking, is the most frequent form of alcohol consumption with poorly understood medical consequences and obscure prophylactics. The study was aimed to determine whether lycosome formulated phosphatidylcholine (PC-Lyc) containing two highly bioavailable antioxidants (PC and lycopene) ingested shortly before the alcohol-containing beverage may alleviate the biochemical markers of liver damage and parameters of biological oxidation associated with the intake of a moderate amount of alcohol. Healthy middle-aged volunteers were requested to consume a moderate amount of alcohol – 0.5 ml/kg or 1.0 ml/kg shortly after ingestion of a capsule containing 450 mg of regular phosphatidylcholine (PC, n=10), PC-Lyc (n=10), or placebo pill (PP, n=10). Serum levels of ethanol (EtOH), acetaldehyde (AA), liver-specific enzymes, total antioxidant capacity of serum (TAC), oxidized LDL (LDL-Px), and malonic dialdehyde (MDA) were measured at 1, 2.5, and 5 hours after dosing with alcohol. Ingestion of PC regardless of the formulation used had no effect on serum EtOH concentration dynamics. However, volunteers supplemented with PC-Lyc showed a better clearance of AA in serum as compared to other groups. There was a reduction in serum TAC values by 18.5% and 16.1% in both placebo groups ingesting 0.5 and 1.0 ml/kg of alcohol, respectively, at the end of observational period. This decline was preventable by supplementation of volunteers with PC and especially with PC-Lyc. Moreover, PC-Lyc promoted a reduction of serum MDA and reversed an increase in serum LDL-Px. In addition, ingestion of alcohol at 1.0 ml/kg dose caused a transient increase in serum alanine-aminotransferase activity which was abolished by both formulations of PC. Therefore, combinatory lycosomal formulation of PC and lycopene may prevent some metabolic abnormalities associated with single intake of moderate amount of alcohol. This trial is registered with ACTRN12617001335381.

Enhanced nitric oxide-mediated autophagy contributes to the hepatoprotective effects of ischemic preconditioning during ischemia and reperfusion

Ischemic preconditioning (IPC) protects against liver ischemia/reperfusion (I/R) injury. Autophagy is an essential cytoprotective system that is rapidly activated by multiple stressors. Nitric oxide (NO) acts as an inducer of IPC. We examined the impact of autophagy in liver IPC and its regulation by NO. Male C57BL/6 mice were subjected to 60 min of hepatic ischemia followed by 6 h of reperfusion. IPC was achieved for 10 min of ischemia followed by 10 min of reperfusion prior to sustained ischemia. Nω-Nitro-l-arginine methyl ester (L-NAME, 15 mg/kg, i.v., all NOS inhibitor) and aminoguanidine (AG, 10 mg/kg, i.v., iNOS inhibitor) were injected 10 min before IPC. SB203580 (10 mg/kg, i.p., p38 inhibitor) was injected 30 min before IPC. I/R increased serum alanine aminotransferase activity. IPC attenuated this increase, which was abolished by L-NAME, but not AG. Microtubule-associated protein-1 light chain 3-II levels increased and p62 protein levels decreased after I/R; these changes were augmented by IPC and abolished by L-NAME. I/R increased liver protein expression of autophagy-related protein (Atg)12-Atg5 complex and lysosome-associated membrane protein-2. IPC augmented the expression of these proteins, which were abolished by L-NAME, but not AG. IPC also augmented the level of phosphorylated p38 MAPK induced by I/R and this phosphorylation was abolished by L-NAME. Our findings suggest that IPC-mediated NO protects against I/R-induced liver injury by enhancing autophagic flux.

Targeting mitochondria with methylene blue protects mice against acetaminophen-induced liver injury.

Acetaminophen (APAP) overdose is a frequent cause of drug-induced liver injury and the most frequent cause of acute liver failure in the Western world. Previous studies with mouse models have revealed that impairment of mitochondrial respiration is an early event in the pathogenesis, but the exact mechanisms have remained unclear, and therapeutic approaches to specifically target mitochondria have been insufficiently explored. Here, we found that the reactive oxidative metabolite of APAP, N-acetyl-p-benzoquinoneimine (NAPQI), caused the selective inhibition of mitochondrial complex II activity by >90% in both mouse hepatic mitochondria and yeast-derived complexes reconstituted into nanoscale model membranes, as well as the decrease of succinate-driven adenosine triphosphate (ATP) biosynthesis rates. Based on these findings, we hypothesized that methylene blue (MB), a mitochondria-permeant redox-active compound that can act as an alternative electron carrier, protects against APAP-induced hepatocyte injury. We found that MB (<3 µM) readily accepted electrons from NAPQI-altered, succinate-energized complex II and transferred them to cytochrome c, restoring ATP biosynthesis rates. In cultured mouse hepatocytes, MB prevented the mitochondrial permeability transition and loss of intracellular ATP without interfering with APAP bioactivation. In male C57BL/6J mice treated with APAP (450 mg/kg, intraperitoneally [IP]), MB (10 mg/kg, IP, administered 90 minutes post-APAP) protected against hepatotoxicity, whereas mice treated with APAP alone developed massive centrilobular necrosis and increased serum alanine aminotransferase activity. APAP treatment inhibited complex II activity ex vivo, but did not alter the protein expression levels of subunits SdhA or SdhC after 4 hours. MB can effectively protect mice against APAP-induced liver injury by bypassing the NAPQI-altered mitochondrial complex II, thus alleviating the cellular energy crisis. Because MB is a clinically used drug, its potential application after APAP overdose in patients should be further explored.

Chronic administration of fluoxetine or clozapine induces oxidative stress in rat liver: A histopathological study

Chronic exposure to stress contributes to the etiology of mood disorders, and the liver as a target organ of antidepressant and antipsychotic drug metabolism is vulnerable to drug-induced toxicity. We investigated the effects of chronic administration of fluoxetine (15mg/kg/day) or clozapine (20mg/kg/day) on liver injury via the measurement of liver enzymes, oxidative stress and histopathology in rats exposed to chronic social isolation (21days), an animal model of depression, and controls. The activity of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST), the liver content of carbonyl groups, malonyldialdehyde (MDA), reduced glutathione (GSH), cytosolic glutathione S-transferase (GST) and nitric oxide (NO) metabolites were determined. We also characterized nuclear factor-κB (NF-κB), cyclooxygenase-2 (COX-2) and CuZn-superoxide dismutase (CuZnSOD) protein expression as well as histopathological changes. Increased serum ALT activity in chronically-isolated and control animals treated with both drugs was found while increased AST activity was observed only in fluoxetine-treated rats (chronically-isolated and controls). Increased carbonyl content, MDA, GST activity and decreased GSH levels in drug-treated controls/chronically-isolated animals suggest a link between drugs and hepatic oxidative stress. Increased NO levels associated with NF-κB activation and the concomitant increased COX-2 expression together with compromised CuZnSOD expression in clozapine-treated chronically-isolated rats likely reinforce oxidative stress, observed by increased lipid peroxidation and GSH depletion. In contrast, fluoxetine reduced NO levels in chronically-isolated rats. Isolation induced oxidative stress but histological changes were similar to those observed in vehicle-treated controls. Chronic administration of fluoxetine in both chronically-isolated and control animals resulted in more or less normal hepatic architecture, while clozapine in both groups resulted in liver injury. These data suggest that clozapine appears to have a higher potential to induce liver toxicity than fluoxetine.

Alanine Aminotransferase Activity in Hypothyroid Patients: A Cross Sectional Study

Background: Hypothyroidism is associated with many biochemical abnormalities including increased serum alanine aminotransferase activity. Very few studies have been done regarding serum alanine aminotransferase activity in hypothyroid patients and, as far we know, no such study has been done in our populations. So, we designed this study in our population for evaluation of serum alanine aminotransferase activity in hypothyroid patients. The objective of this study was to assess serum alanine aminotransferase activity in hypothyroid patients and to find out relationship of alanine aminotransferase activity with severity of hypothyroidism. Methods: It was a retrospective cross sectional study to evaluate the serum alanine aminotransferase activity of hypothyroid patients and to find out relationship of alanine aminotransferase activity with severity of hypothyroidism and the values were compared with that of age and sex matched healthy euthyroid controls. Statistical analyses were performed by using SPSS for Windows version 12.0. Unpaired ‘t’ test was done to find out any significant difference between the cases and controls with respect to age and serum alanine aminotransferase activity. Chisquare test was done to find out any significant difference between the cases and controls with respect to sex. Pearson correlation coefficient test was done to see the correlation of alanine aminotransferase activity with the severity of hypothyroidism. Results: Mean serum alanine aminotransferase activity was found significantly higher in hypothyroid patients compared to that of controls. Conclusion: Results of our study suggest that increased serum alanine aminotransferase activity is associated with hypothyroidism. Therefore, patients presenting with increased ALT activity with normal liver function tests are recommended to be investigated to explore hypothyroidism. Chattagram Maa-O-Shishu Hospital Medical College Journal Volume 12, Issue 3, September 2013: 49-51

Losartan protects liver against ischaemia/reperfusion injury through PPAR‐γ activation and receptor for advanced glycation end‐products down‐regulation

PPAR-γ has been reported to be a protective regulator in ischaemia/reperfusion (I/R) injury. The receptor for advanced glycation end-products (RAGE) plays a major role in the innate immune response, and its expression is associated with PPAR-γ activation. Several angiotensin receptor blockers possess partial agonist activities towards PPAR-γ. Therefore, this study investigated the action of losartan, particularly with regard to PPAR-γ activation and RAGE signalling pathways during hepatic I/R. Mice were subjected to 60 min of ischaemia followed by 6 h of reperfusion. Losartan (0.1, 1, 3 and 10 mg · kg⁻¹) was administered 1 h prior to ischaemia and immediately before reperfusion. GW9662, a PPAR-γ antagonist, was administered 30 min prior to first pretreatment with losartan. Losartan enhanced the DNA-binding activity of PPAR-γ in I/R. Losartan attenuated the increased serum alanine aminotransferase activity, TNF-α and IL-6 levels, and nuclear concentrations of NF-κB in I/R. GW9662 reversed these beneficial effects. Losartan caused a decrease in apoptosis as assessed by TUNEL assay, in release of cytochrome c and in cleavage of caspase-3, and these effects were abolished by GW9662 administration. Losartan attenuated not only I/R-induced RAGE overexpression, but also its downstream early growth response protein-1-dependent macrophage inflammatory protein 2 level; phosphorylation of p38, ERK and JNK; and subsequent c-Jun phosphorylation. GW9662 reversed these effects of losartan administration. Our findings suggest that losartan ameliorates I/R-induced liver damage through PPAR-γ activation and down-regulation of the RAGE signalling pathway.

Fibrinogen Deficiency Increases Liver Injury and Early Growth Response-1 (Egr-1) Expression in a Model of Chronic Xenobiotic-Induced Cholestasis

Chronic cholestatic liver injury induced by cholestasis in rodents is associated with hepatic fibrin deposition, and we found evidence of fibrin deposition in livers of patients with cholestasis. Key components of the fibrinolytic pathway modulate cholestatic liver injury by regulating activation of hepatocyte growth factor. However, the exact role of hepatic fibrin deposition in chronic cholestasis is not known. We tested the hypothesis that fibrinogen (Fbg) deficiency worsens liver injury induced by cholestasis. Fbg-deficient mice (Fbgα(-/-) mice) and heterozygous control mice (Fbgα(+/-) mice) were fed either the control diet or a diet containing 0.025% α-naphthylisothiocyanate (ANIT), which selectively injures bile duct epithelial cells in the liver, for 2 weeks. Hepatic fibrin and collagen deposits were evident in livers of heterozygous control mice fed the ANIT diet. Complete Fbg deficiency was associated with elevated serum bile acids, periportal necrosis, and increased serum alanine aminotransferase activity in mice fed the ANIT diet. Fbg deficiency was associated with enhanced hepatic expression of the transcription factor early growth response-1 (Egr-1) and enhanced induction of genes encoding the Egr-1-regulated proinflammatory chemokines monocyte chemotactic protein-1, KC growth-regulated protein, and macrophage inflammatory protein-2. Interestingly, peribiliary collagen deposition was not evident near necrotic areas in Fbg-deficient mice. The results suggest that in this model of chronic cholestasis, fibrin constrains the release of bile constituents from injured intrahepatic bile ducts, thereby limiting the progression of hepatic inflammation and hepatocellular injury.

Relationship of hepatic steatosis and alanine aminotransferase with coronary calcification

It has been observed that hepatic steatosis is related to an increased risk of cardiovascular disease (CVD). Alanine aminotransferase (ALT), an indicator of the severity of hepatic steatosis is also associated with CVD. This study focused on the relationship between hepatic steatosis and ALT with coronary calcification. We performed a cross-sectional study to examine the association between hepatic steatosis and serum ALT with coronary calcification in 1218 subjects (772 men, 446 women; ages 30-75 years). We evaluated hepatic steatosis and ALT as categorical variables, and constructed four groups (reference group; only with hepatic steatosis; only with ALT >30 U/L; with both hepatic steatosis and ALT >30 U/L), which did not overlap. Multi-detected row computed tomography (MDCT) was used to measure coronary calcium score. The adjusted ORs (95% CIs) for coronary calcification in the four groups were 1.00 (reference), 1.24 (0.68-2.26), 1.82 (0.78-4.23), and 2.12 (1.08-4.20) after adjusting for confounding variables. In addition, an increase in serum ALT activity of 10 U/L was associated with an increased risk of coronary atherosclerosis. In summary, patients with both hepatic steatosis and increases in ALT are associated with coronary calcification as a marker of coronary atherosclerosis determined by MDCT. This finding suggested that subjects with both hepatic steatosis and increased ALT should be considered for further evaluation of coronary atherosclerosis.

Tissue Factor-Deficiency and Protease Activated Receptor-1-Deficiency Reduce Inflammation Elicited by Diet-Induced Steatohepatitis in Mice

Altered hepatic lipid homeostasis, hepatocellular injury, and inflammation are features of nonalcoholic steatohepatitis, which contributes significantly to liver-related morbidity and mortality in the Western population. A collection of inflammatory mediators have been implicated in the pathogenesis of steatohepatitis in mouse models. However, the pathways essential for coordination and amplification of hepatic inflammation and injury caused by steatosis are not completely understood. We tested the hypothesis that tissue factor (TF)-dependent thrombin generation and the thrombin receptor protease activated receptor-1 (PAR-1) contribute to liver inflammation induced by steatosis in mice. Wild-type C57Bl/6J mice fed a diet deficient in methionine and choline for 2 weeks manifested steatohepatitis characterized by increased serum alanine aminotransferase activity, macrovesicular hepatic steatosis, hepatic inflammatory gene expression, and lobular inflammation. Steatohepatitis progression was associated with thrombin generation and hepatic fibrin deposition. Coagulation cascade activation was significantly reduced in low TF mice, which express 1% of normal TF levels. Hepatic triglyceride accumulation was not affected in low TF mice or PAR-1-deficient mice. In contrast, biomarkers of hepatocellular injury, inflammatory gene induction, and hepatic accumulation of macrophages and neutrophils were greatly reduced by TF-deficiency and PAR-1-deficiency. The results suggest that TF-dependent thrombin generation and activation of PAR-1 amplify hepatic inflammation and injury during the pathogenesis of steatohepatitis.

Bacterial- and Viral-Induced Inflammation Increases Sensitivity to Acetaminophen Hepatotoxicity

Acetaminophen (APAP)-induced hepatotoxicity accounts for nearly half of acute liver failure cases in the United States. The doses that produce hepatotoxicity vary considerably and many risk factors have been proposed, including liver inflammation from viral hepatitis. Interestingly, inflammatory stress from another stimulus, bacterial endotoxin (lipopolysaccharide, LPS), renders the liver more sensitive to hepatotoxicity from numerous xenobiotic agents. The purpose of these studies was to test the hypothesis that inflammation induced by LPS or infection with reovirus increases sensitivity to APAP-induced liver injury. For LPS-induced inflammation, C57BL/6J mice were treated with either saline or LPS (44 × 106 EU/kg, ip) 2 h before treatment with APAP (100–400 mg/kg, ip) or saline. No elevation in serum alanine aminotransferase (ALT) activity was observed in mice that received vehicle or LPS alone. LPS co-treatment produced a leftward shift of the dose-response curve for APAP-induced hepatotoxicity and led to significantly greater tumor necrosis factor-α (TNF) production than APAP alone. Reovirus serotype 1 (108 PFU, iv) induced inflammation in Balb/c mice as evidenced by increases in hepatic mRNAs for macrophage inhibitory protein-2, interleukin-6, and TNF. Co-administration of reovirus and APAP at doses of 450 and 700 mg/kg (2 h after reovirus) led to increases in serum ALT activity, whereas neither reovirus nor APAP alone produced liver injury. Consistent with the increases in serum ALT activity, histopathologic examination revealed centrilobular necrosis with marked neutrophilic accumulation only in livers of mice treated with LPS/APAP or with reovirus/APAP. The results suggest that normally noninjurious doses of APAP are rendered hepatotoxic by modest inflammation, whether bacterial or viral in origin.

Cytosolic distribution of Cd, Cu and Zn, and metallothionein levels in relation to physiological changes in gibel carp ( Carassius auratus gibelio) from metal-impacted habitats

In the present study the impact of environmental metal contamination in gibel carp ( Carassius auratus gibelio) was investigated coupling disturbances in subcellular metal distribution to effect biomarkers. Gibel carp were caught at six different sampling sites in Flanders (Belgium), characterized by different degrees in environmental metal contamination. Tissue Cd, Cu and Zn concentrations and total metallothioneon (MT) levels were determined in gills, liver and kidney. Cytosolic metal distribution was measured in the main accumulating organs, liver and kidney, revealing tissue- and metal-dependent profiles. The MT pool dominated the cytosolic distribution profile. Although the importance of the MT pool increased with increasing environmental and cytosolic metal concentrations, also an undefined fraction of Cu and Cd fractions (probably free metal ions or metals bound to small organic complexes) increased at the most contaminated sampling sites. Disturbances in serum ion concentrations, serum alanine aminotransferase activity (ALT), hematocrite and condition factor were measured, as indicators of toxic effects. At the sampling site with the highest environmental Cd pollution a significant decrease in serum Ca 2+ concentrations and a significantly increased serum ALT activity were measured suggesting incomplete detoxification of Cd. Increased serum ALT concentrations suggested structural liver damage. The fact that the liver tissue, and probably also the kidney, could not cope with this high Cd burden in combination with the increased uptake of dissolved Cd through the gills most probably contributed to the perturbed serum Ca 2+ homeostasis.

Farnesoid X Receptor Deficiency Induces Nonalcoholic Steatohepatitis in Low-Density Lipoprotein Receptor-Knockout Mice Fed a High-Fat Diet

Nonalcoholic steatohepatitis (NASH) comprises dysregulation of lipid metabolism and inflammation. Identification of the various genetic and environmental susceptibility factors for NASH may provide novel treatments to limit inflammation and fibrosis in patients. This study utilized a mouse model of hypercholesterolemia, low-density lipoprotein receptor knockout (LDLr(-/-)) mice fed a high-fat diet for 5 months, to test the hypothesis that farnesoid X receptor (FXR) deficiency contributed to NASH development. Either the high-fat diet or FXR deficiency increased serum alanine aminotransferase activity, whereas only FXR deficiency increased bile acid and alkaline phosphatase levels. FXR deficiency and high-fat feeding increased serum cholesterol and triglycerides. Although high fat led to macrosteatosis and hepatocyte ballooning in livers of mice regardless of genotype, no inflammatory infiltrate was observed in the livers of LDLr(-/-) mice. In contrast, in the livers of LDLr(-/-)/FXR(-/-) mice, foci of inflammatory cells were observed occasionally when fed the control diet and were greatly increased when fed the high-fat diet. Consistent with enhanced inflammatory cells, hepatic levels of tumor necrosis factor alpha and intercellular adhesion molecule-1 mRNA were increased by the high-fat diet in LDLr(-/-)/FXR(-/-) mice. In agreement with elevated levels of procollagen 1 alpha 1 and TGF-beta mRNA, type 1 collagen protein levels were increased in livers of LDLr(-/-)/FXR(-/-) mice fed a high-fat diet. In conclusion, FXR deficiency induces pathologic manifestations required for NASH diagnosis in a mouse model of hypercholesterolemia, including macrosteatosis, hepatocyte ballooning, and inflammation, which suggest a combination of FXR deficiency and high-fat diet is a risk factor for NASH development, and activation of FXR may be a therapeutic intervention in the treatment of NASH.

Ibuprofen administration attenuates serum TNF-α levels, hepatic glutathione depletion, hepatic apoptosis and mouse mortality after Fas stimulation

Fas stimulation recruits neutrophils and activates macrophages that secrete tumor necrosis factor-α (TNF-α), which aggravates Fas-mediated liver injury. To determine whether nonsteroidal anti-inflammatory drugs modify these processes, we challenged 24-hour-fasted mice with the agonistic Jo2 anti-Fas antibody (4 µg/mouse), and treated the animals 1 h later with saline or ibuprofen (250 mg/kg), a dual cyclooxygenase (COX)-1 and COX-2 inhibitor. Ibuprofen attenuated the Jo2-mediated recruitment/activation of myeloperoxidase-secreting neutrophils/macrophages in the liver, and attenuated the surge in serum TNF-α. Ibuprofen also minimized hepatic glutathione depletion, Bid truncation, caspase activation, outer mitochondrial membrane rupture, hepatocyte apoptosis and the increase in serum alanine aminotransferase (ALT) activity 5 h after Jo2 administration, to finally decrease mouse mortality at later times. The concomitant administration of pentoxifylline (decreasing TNF-α secretion) and infliximab (trapping TNF-α) likewise attenuated the Jo2-mediated increase in TNF-α, the decrease in hepatic glutathione, and the increase in serum ALT activity 5 h after Jo2 administration. The concomitant administration of the COX-1 inhibitor, SC-560 (10 mg/kg) and the COX-2 inhibitor, celecoxib (40 mg/kg) 1 h after Jo2 administration, also decreased liver injury 5 h after Jo2 administration. In contrast, SC-560 (10 mg/kg) or celecoxib (40 or 160 mg/kg) given alone had no significant protective effects. In conclusion, secondary TNF-α secretion plays an important role in Jo2-mediated glutathione depletion and liver injury. The combined inhibition of COX-1 and COX-2 by ibuprofen attenuates TNF-α secretion, glutathione depletion, mitochondrial alterations, hepatic apoptosis and mortality in Jo2-treated fasted mice.

Different mechanisms of modulation of gap junction communication by non-genotoxic carcinogens in rat liver in vivo

This is a comparative study of the mechanisms by which three different rodent non-genotoxic carcinogens modulate connexin-mediated gap junction intercellular communication in male rat liver in vivo. In the case of the peroxisome proliferating agent Wy-14,643, a non-hepatotoxic dose of 50 mg/kg led to a marked loss of inter-hepatocyte dye transfer associated with a loss of both Cx32 and Cx26 protein expression. In contrast, p, p′-dichlorodiphenyltrichloroethane (DDT) at a non-hepatotoxic dose (25 mg/kg) was not found to alter Cx32 or Cx26 expression or to produce a measurable Cx32 serine phosphorylation but did give a small, significant reduction of cell communication. Carbon tetrachloride (CCl 4) did not affect cell communication (despite a small significant reduction of Cx32 content) at a non-hepatotoxic dose. Both loss of communication and Cx32 expression was observed only at a dose that caused hepatocyte toxicity as evidenced by increased serum alanine aminotransferase activity. Overall, the findings emphasise that loss of gap junctional communication in vivo can contribute to carcinogenesis by non-genotoxic carcinogens through different primary mechanism. In contrast to Wy-14,643 and DDT, the results with CCl 4 are consistent with a requirement for hepatotoxicity in its carcinogenic action.

Troglitazone-Induced Hepatic Necrosis in an Animal Model of Silent Genetic Mitochondrial Abnormalities

Troglitazone, a first-generation thiazolidinedione antidiabetic drug, was withdrawn from the market due to an unacceptable risk of idiosyncratic hepatotoxicity. Troglitazone does not cause hepatotoxicity in normal healthy rodents, but it produces mitochondrial injury in vitro at high concentrations. The aim of this study was to explore whether genetic mitochondrial abnormalities might sensitize mice to hepatic adverse effects of troglitazone. We used heterozygous superoxide dismutase 2 (Sod2(+/-)) mice as a model of clinically silent mitochondrial stress. Troglitazone was daily administered for 4 weeks (0, 10 or 30 mg/kg/day, ip). We found that troglitazone caused overt liver injury in the high-dose group, manifested by increased serum alanine aminotransferase activity (> twofold) and midzonal areas of hepatic necrosis, in Sod2(+/-) but not in wild-type mice. No signs of hepatotoxicity were apparent at 2 weeks of treatment. Hepatic mitochondria isolated from troglitazone-treated mice exhibited decreased activities of aconitase (by 45%) and complex I (by 46%) and increased (by 58%) protein carbonyls, indicative of enhanced mitochondrial oxidant stress. This was paralleled by compensatory increases in mitochondrial glutathione levels. Finally, in hepatocytes isolated from untreated Sod2(+/-), but not wild-type mice, troglitazone caused a concentration-dependent increase in superoxide anion levels as demonstrated with a selective mitochondria-targeting fluorescent probe. In conclusion, prolonged administration of troglitazone can superimpose oxidant stress, potentiate mitochondrial damage, and induce delayed hepatic necrosis in mice with genetically compromised mitochondrial function. These data are consistent with our hypothesis that inherited or acquired mitochondrial abnormalities may be one of the contributing determinants of susceptibility to troglitazone-induced idiosyncratic liver injury.