Plasma Alanine Aminotransferase Activity Research Articles

Comparative NMR-Based Metabonomic Investigation of the Metabolic Phenotype Associated with Tienilic Acid and Tienilic Acid Isomer

An NMR-based metabonomic approach was applied to study the systems level metabolic effects of two closely related thiophene compounds, tienilic acid (TA) and tienilic acid isomer (TAI). The metabonomic data were anchored with traditional clinical chemistry and histopathologic analyses. TA was removed from the market as a result of suspected immune-mediated hepatotoxicity, whereas TAI is an intrinsic hepatotoxin. Equimolar doses of TA and TAI were administered to Sprague-Dawley rats, and sampling was conducted at 2, 6, and 24 h post-treatment. Histopathologic analyses revealed development of a significant hepatic lesion 24 h post-TAI treatment with a parallel increase in plasma alanine aminotransferase (ALT) activity. In contrast, TA was not associated with the development of a hepatic lesion or an increase in plasma ALT activity. High-resolution NMR spectral metabolic profiles were generated for liver extracts, plasma, and urine at multiple time points. Multivariate statistical tools were applied to model the metabolic profiles and identify discriminatory metabolites that reflected both the adaptation to TA administration and the onset and progression of TAI-induced hepatotoxicity. TAI was shown to induce marked metabolic effects on the metabolome at all time points, with dramatic metabolic perturbations at 24 h post-treatment correlating with the histopathologic and clinical chemistry evidence of a hepatic lesion. The TAI-induced metabolic perturbations provided evidence for the generation of electrophilic reactive metabolites and a significant impairment of bioenergetic metabolic pathways. TA induced early metabolic perturbations that were largely resolved by 24 h post-treatment, suggesting the reestablishment of metabolic homeostasis and the ability to adapt to the intervention, with hepatic hypotaurine potentially representing a means of assessment of hepatic adaptation. This comparative metabonomic approach enabled the discrimination of metabolic perturbations that were common to both treatments and were interpreted as nontoxic thiophene-induced perturbations. Importantly, this approach enabled the identification of temporal metabolic perturbations that were unique to TAI or TA treatment and hence were of relevance to the development of toxicity or the ability to adapt. This approach is applicable to the future study of pharmacologically and structurally similar compounds and represents a refined means of identification of biomarkers of toxicity.

Isoform-specific alanine aminotransferase measurement can distinguish hepatic from extrahepatic injury in humans

Serum alanine aminotransferase (ALT) is used as a clinical marker to detect hepatic damage and hepatoxicity. Two isoforms of ALT have been identified, ALT1 and ALT2, which have identical enzymatic capacities and are detected simultaneously in human serum/plasma using classical clinical chemical assays. Differences exist in the expression patterns of the ALT1 and ALT2 proteins in different organs which suggest that changes in the proportion of ALT1 and ALT2 in plasma may arise and reflect damage to different human organs. However, this has not been previously studied due to the lack of a selective methodology that can quantify both ALT1 and ALT2 isoforms in the total ALT activity normally measured in clinical samples. To the best of our knowledge, our current study reveals for the first time, that under 3 different conditions of liver damage (non-alcoholic fatty liver disease, hepatitis C and during liver surgery) the leakage of ALT1 activity into plasma greatly exceeds that of ALT2, and that the measurement of ALT1 during liver damage is equal to the measurement of total ALT activity. By contrast, during skeletal muscle injury, induced in volunteers by physical exertion, the leakage of ALT2 exceeds that of ALT1 and the proportion of circulating ALT isoforms changes accordingly. The ALT isoform changes occurring in plasma reflect previously demonstrated relative contents of ALT1 and ALT2 activities in human liver and skeletal muscle. These data suggest that assessing the percentage contribution of ALT1 and ALT2 activities to total ALT activity in plasma may distinguish hepatic from extrahepatic injury using the same standard analytical platform.

Melatonin Protection against Burn-Induced Hepatic Injury by Down-Regulation and Nuclear Factor Kappa B Activation

Melatonin exhibits a wide variety of biological activity including antioxidant and anti-inflammatory effects. We have previously reported its protective effect on hepatic oxidative hepatic injury in burns. In this study, we investigated the role of nuclear factor kappa B (NF-κB) in melatonin-mediated protection against liver injury by using the burned-rat model. Melatonin (N-acetyl-5-methoxytriptamin, 10mg/kg (-1), i.p.) was administered immediately and 12 hours after thermal skin injury. Hepatic NF-κB expression was determined by Western blotting. TNF-α level in liver homogenate was quantified using enzyme-linked immunosorbent assay (ELISA) kit. Plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were determined to assess liver injury at the 24th hour after burns. Thermal skin injury caused significant elevation of hepatic NF-κB expression by 48 percent, TNF-α level by 55 percent and plasma AST and ALT activities by 2- and 3-fold, respectively, in comparison with normal control rats. Treatment with melatonin decreased significantly elevated hepatic NF-κB activity and TNF-α, maintaining the levels close to the control values Melatonin suppressed the elevation of plasma AST and ALT activities (p less than 0.001), which remained significantly increased compared to controls. In conclusion, thermal skin injury causes hepatic NF-κB activation that may mediate the release of hepatic TNF-α and contribute to liver damage. Melatonin protects against burn-induced hepatic injury as to a certain extent this effect may result from the suppression of NF-κB-mediated inflammatory response.

Induction of Nrf2-dependent Antioxidation and Protection Against Carbon Tetrachloride-induced Liver Damage by Andrographis Herba (穿心蓮chuān xīn lián) Ethanolic Extract

Andrographis paniculata is a traditional Chinese herb and displays diverse biological activities including antioxidation, anti-tumorigenesis, anti-virus, and anti-atherogenesis. In this study, we investigated the up-regulation of ethanolic extract of A. paniculata (APE) on the antioxidant defense in rat livers and whether this enhancement protected against carbon tetrachloride (CCl4)-induced liver damage. Male Sprague-Dawley rats were orally administered (i.g.) 0, 0.75, or 2g/kg/d APE for 5 d. At d 6, rats were sacrificed and liver tissues were removed. Some animals (n=8) were intraperitoneally injected CCl4 (1mL/kg, 50% in olive oil) and blood was drawn 24h after CCl4 treatment. The results showed that APE increased hepatic glutathione (GSH) content and superoxide dismutase, GSH peroxidase, and GSH S-transferase activities in a dose-dependent manner (p<0.05). Results of immunoblotting and RT-PCR revealed that rats treated with APE had higher glutamate cysteine ligase catalytic and modifier subunits, heme oxygenase 1, superoxide dismutase 1, and GSH S-transferase Ya and Yb protein and mRNA expression than those of control rats. Moreover, APE increased Nrf2 nuclear translocation and Nrf2 binding to DNA in rat liver. In the presence of CCl4, APE decreased hepatic thiobarbituric acid-reactive substances production and plasma aspartate aminotransferase and alanine aminotransferase activities. These results suggest that APE protection against CCl4 insult is attributed, at least in part, to its up-regulation of antioxidant defense in rat liver.

Supplementation with branched-chain amino acids attenuates hepatic apoptosis in rats with chronic liver disease

Branched-chain amino acids (BCAA) can function as pharmacologic nutrients for patients with decompensated cirrhosis. However, the effects of BCAA at the early stage of chronic liver disease are not clear. We hypothesized that early BCAA supplementation would attenuate the progression of chronic liver disease. The present study examined the effects of BCAA supplementation on the progression of chronic liver disease in rats caused by injected carbon tetrachloride (CCl₄). Sprague-Dawley rats were fed with a casein diet (control group) or the same diet supplemented with BCAA (BCAA group) for 11 weeks, and all rats were repeatedly injected with CCl₄. Food intake did not significantly differ between control and BCAA groups during the experimental period. Plasma alanine aminotransferase activities gradually increased during the experimental period in both groups but peaked later in the BCAA group. Liver fibrosis was more evident in the control group. Levels of connective tissue growth factor messenger RNA were significantly lower in the livers of rats in the BCAA group than in the control group. Terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphosphate nick end labeling assays found considerably more hepatic apoptosis in the control group. Liver cytosolic cytochrome c levels and expression of the proapoptotic Bax protein in the mitochondrial fraction were significantly lower in the BCAA group than in the control group. These results suggest that supplementation with BCAA delays the progression of chronic liver disease caused by CCl₄ in rats by attenuating hepatic apoptosis.

Inhaled Hydrogen Sulfide Prevents Endotoxin-Induced Systemic Inflammation and Improves Survival by Altering Sulfide Metabolism in Mice

The role of hydrogen sulfide (H(2)S) in endotoxin (lipopolysaccharide [LPS])-induced inflammation is incompletely understood. We examined the impact of H(2)S breathing on LPS-induced changes in sulfide metabolism, systemic inflammation, and survival in mice. Mice that breathed air alone exhibited decreased plasma sulfide levels and poor survival rate at 72 h after LPS challenge. Endotoxemia markedly increased alanine aminotransferase (ALT) activity and nitrite/nitrate (NOx) levels in plasma and lung myeloperoxidase (MPO) activity in mice that breathed air. In contrast, breathing air supplemented with 80 ppm of H(2)S for 6 h after LPS challenge markedly improved survival rate compared to mice that breathed air alone (p<0.05). H(2)S breathing attenuated LPS-induced increase of plasma ALT activity and NOx levels and lung MPO activity. Inhaled H(2)S suppressed LPS-induced upregulation of inflammatory cytokines, while it markedly induced anti-inflammatory interleukin (IL)-10 in the liver. Beneficial effects of H(2)S inhalation after LPS challenge were associated with restored sulfide levels and markedly increased thiosulfate levels in plasma. Increased thiosulfate levels after LPS challenge were associated with upregulation of rhodanese, but not cystathionine-γ-lyase (CSE), in the liver. Administration of sodium thiosulfate dose-dependently improved survival after LPS challenge in mice. By measuring changes in plasma levels of sulfide and sulfide metabolites using an advanced analytical method, this study revealed a critical role of thiosulfate in the protective effects of H(2)S breathing during endotoxemia. These observations suggest that H(2)S breathing prevents inflammation and improves survival after LPS challenge by altering sulfide metabolism in mice.

Dietary Coleus forskohlii extract generates dose‐related hepatotoxicity in mice

Coleus forskohlii root extract (CFE) represented by its bioactive constituent 'forskolin' is popularly used as a natural weight-lowering product, but the association of its use with liver-related risks is very limited. In the present study, the effect of standardized CFE with 10% forskolin on liver function of mice was examined. Mice were given 0-5% CFE in an AIN93G-based diet for 3-5 weeks. Food intake, body weights, relative organ weights and liver marker enzymes [aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP)] combined with histophatological analysis were assessed. CFE (0-0.5%) only had minimal effects on food intake and body weight whereas a significant difference was observed in mice receiving the highest dose (5% CFE). The extract 0.05-5% dose-dependently decreased visceral fat weight by between 16% and 63%, and a dose-dependent several folds increase was observed in liver weights and plasma AST, ALT and ALP activities with quick onset apparent after only 1 week of 0.5% CFE intake. The hepatic effect persisted throughout the 3-weeks course but was restored towards normalization within 1 week after withdrawal of treatment. Liver histology of mice fed 0.5% CFE for 3 weeks showed hepatocyte hypertrophy and fat deposition. In contrast, none of the hepatic responses measured were altered when mice were given a diet containing pure forskolin alone at the dose corresponding to its content in 0.5% CFE. The present study clearly indicated that forskolin was not involved in the CFE-induced hepatotoxicity and was caused by other unidentified constituents in CFE which warrants further studies.

Disruption of hemochromatosis protein and transferrin receptor 2 causes iron-induced liver injury in mice

Mutations in hemochromatosis protein (HFE) or transferrin receptor 2 (TFR2) cause hereditary hemochromatosis (HH) by impeding production of the liver iron-regulatory hormone, hepcidin (HAMP). This study examined the effects of disruption of Hfe or Tfr2, either alone or together, on liver iron loading and injury in mouse models of HH. Iron status was determined in Hfe knockout (Hfe(-/-)), Tfr2 Y245X mutant (Tfr2(mut)), and double-mutant (Hfe(-/-) ×Tfr2(mut) ) mice by measuring plasma and liver iron levels. Plasma alanine transaminase (ALT) activity, liver histology, and collagen deposition were evaluated to assess liver injury. Hepatic oxidative stress was assessed by measuring superoxide dismutase (SOD) activity and F(2)-isoprostane levels. Gene expression was measured by real-time polymerase chain reaction. Hfe(-/-) ×Tfr2(mut) mice had elevated hepatic iron with a periportal distribution and increased plasma iron, transferrin saturation, and non-transferrin-bound iron, compared with Hfe(-/-), Tfr2(mut), and wild-type (WT) mice. Hamp1 expression was reduced to 40% (Hfe(-/-) and Tfr2(mut) ) and 1% (Hfe(-/-) ×Tfr2(mut)) of WT values. Hfe(-/-) ×Tfr2(mut) mice had elevated plasma ALT activity and mild hepatic inflammation with scattered aggregates of infiltrating inflammatory cluster of differentiation 45 (CD45)-positive cells. Increased hepatic hydoxyproline levels as well as Sirius red and Masson's Trichrome staining demonstrated advanced portal collagen deposition. Hfe(-/-) and Tfr2(mut) mice had less hepatic inflammation and collagen deposition. Liver F(2) -isoprostane levels were elevated, and copper/zinc and manganese SOD activities decreased in Hfe(-/-) ×Tfr2(mut), Tfr2(mut), and Hfe(-/-) mice, compared with WT mice. Disruption of both Hfe and Tfr2 caused more severe hepatic iron overload with more advanced lipid peroxidation, inflammation, and portal fibrosis than was observed with the disruption of either gene alone. The Hfe(-/-) ×Tfr2(mut) mouse model of iron-induced liver injury reflects the liver injury phenotype observed in human HH.

Mitogen-activated Protein Kinase Phosphatase (Mkp)-1 Protects Mice against Acetaminophen-induced Hepatic Injury

c-Jun N-terminal kinase (JNK) activation promotes hepatocyte death during acetaminophen overdose, a common cause of drug-induced liver failure. While mitogen-activated protein kinase (MAPK) phosphatase (Mkp)-1 is a critical negative regulator of JNK MAPK, little is known about the role of Mkp-1 during hepatotoxicity. In this study, we evaluated the role of Mkp-1 during acute acetaminophen toxicity. Mkp-1⁺/⁺ and Mkp-1⁻/⁻ mice were dosed ip with vehicle or acetaminophen at 300 mg/kg (for mechanistic studies) or 400 mg/kg (for survival studies). Tissues were collected 1-6 hr post 300 mg/kg dosing to assess glutathione levels, organ damage, and MAPK activation. Mkp-1⁻/⁻ mice exhibited more rapid plasma clearance of acetaminophen than did Mkp-1⁺/⁺ mice, indicated by a quicker decline of plasma acetaminophen level. Moreover, Mkp-1⁻/⁻ mice suffered more severe liver injury, indicated by higher plasma alanine transaminase activity and more extensive centrilobular apoptosis and necrosis. Hepatic JNK activity in Mkp-1⁻/⁻ mice was higher than in Mkp-1⁺/⁺ mice. Finally, Mkp-1⁻/⁻ mice displayed a lower overall survival rate and shorter median survival time after dosing with 400 mg/kg acetaminophen. The more severe phenotype exhibited by Mkp-1⁻/⁻ mice indicates that Mkp-1 plays a protective role during acute acetaminophen overdose, potentially through regulation of JNK.

Exercise training attenuates hepatic inflammation, fibrosis and macrophage infiltration during diet induced-obesity in mice

Nonalcoholic steatohepatitis, which is considered the hepatic event in metabolic syndrome, was recently associated with the innate immune system. Although regular exercise reduces hepatic injury markers like serum alanine aminotransferase (ALT) levels, the mechanisms regulating the effects of exercise on steatohepatitis are unclear. This study aimed to clarify whether exercise training suppresses hepatic injury, inflammation, and fibrosis by suppressing macrophage infiltration. Male C57BL/6J (4-week old) mice were randomly divided into four groups: normal diet (ND) control (n=7), ND exercise (n=5), high-fat diet and high-fructose water (HFF) control (n=11), and HFF exercise (n=11) groups. Mice were fed the ND or HFF from 4 to 20 weeks of age. The exercise groups were trained on a motorized treadmill for 60 min/day, five times/week. The nonalcoholic fatty liver disease (NAFLD) activity score and plasma ALT activity, indicators of liver injury, were increased in HFF control mice but were attenuated in HFF exercise mice. Hepatic inflammation, indicated by hepatic tumor necrosis factor (TNF)-α levels and hepatic resident macrophage infiltration, was significantly lower in HFF exercise mice than in HFF control mice. Hepatic fibrosis markers (histological hepatic fibrosis detected by Sirius red and α-smooth muscle actin staining and tissue inhibitor of matrix metalloproteinase-1 mRNA) were attenuated in HFF exercise mice compared with HFF control mice. These results suggest that exercise training reduces hepatic inflammation, injury, and fibrosis by suppressing macrophage infiltration.

Rapid Release of Tissue Enzymes into Blood after Blast Exposure: Potential Use as Biological Dosimeters

Explosive blast results in multiple organ injury and polytrauma, the intensity of which varies with the nature of the exposure, orientation, environment and individual resilience. Blast overpressure alone may not precisely indicate the level of body or brain injury after blast exposure. Assessment of the extent of body injury after blast exposure is important, since polytrauma and systemic factors significantly contribute to blast-induced traumatic brain injury. We evaluated the activity of plasma enzymes including aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH) and creatine kinase (CK) at different time points after blast exposure using a mouse model of single and repeated blast exposures to assess the severity of injury. Our data show that activities of all the enzymes in the plasma were significantly increased as early as 1 h after blast exposure. The elevated enzyme activity remained up to 6 h in an overpressure dose-dependent manner and returned close to normal levels at 24 h. Head-only blast exposure with body protection showed no increase in the enzyme activities suggesting that brain injury alone does not contribute to the systemic increase. In contrast to plasma increase, AST, ALT and LDH activity in the liver and CK in the skeletal muscle showed drastic decrease at 6 h after blast exposures. Histopathology showed mild necrosis at 6 h and severe necrosis at 24 h after blast exposures in liver and no changes in the skeletal muscle suggesting that the enzyme release from the tissue to plasma is probably triggered by transient cell membrane disruption from shockwave and not due to necrosis. Overpressure dependent transient release of tissue enzymes and elevation in the plasma after blast exposure suggest that elevated enzyme activities in the blood can be potentially used as a biological dosimeter to assess the severity of blast injury.

Diverse Effects of a Low Dose Supplement of Lipidated Curcumin in Healthy Middle Aged People

Curcumin extracts of turmeric are proposed to produce health benefits. However, such supplements often show poor absorption and have generally been tested just in people with existing health problems. In a new study, healthy middle aged men and women were given a low dose (80 mg) of curcumin in a form expected to have good absorption (LONGVIDA®, a mix of curcumin +stearic acid+lecithin+other ingredients). Curcumin (N=19), but not placebo (N=19), had diverse effects: lowered plasma triglyceride values, lowered salivary amylase levels, raised salivary radical scavenging capacities, raised plasma catalase activities, lowered plasma beta amyloid protein concentrations, lowered plasma sICAM readings, increased plasma myeloperoxidase without increased c‐reactive protein, increased plasma nitric oxide, and decreased plasma alanine amino transferase activities. Collectively, these results show that a low dose of a curcumin can produce a variety of potentially health promoting effects in healthy middle aged people. Although the study did not measure curcumin absorption directly, the effects on multiple body measures suggests efficient absorption. The work was supported by Verdure Sciences.

Impacts of RegIIIβ inactivation on murine hepatic protein nitration induced by acetaminophen

As the mouse homologue of human hepatocarcinoma‐intestine‐pancreas/ pancreatic‐associated protein, RegIIIβ is involved in liver regeneration. Because knockout of RegIIIβ rendered mice susceptible to acetaminophen (APAP) toxicity, we conducted a series of experiments to determine if the protein affected the APAP‐induced hepatic nitrotyrosine formation. At 5 h after mice (8‐wk old, n = 5/group) were injected with APAP (300 mg/kg, ip), the knockout group exhibited stronger hepatic protein nitration than the wild‐type (WT). Meanwhile, pre‐treating the knockout mice with a recombinant RegIIIβ protein (6 mg/kg, ip) at 6 h prior to the APAP treatment greatly attenuated (P &lt; 0.05) the APAP‐induced hepatic protein nitration, hepatic glutathione depletion, and plasma alanine transaminase activity rise. Subsequent characterization of hepatic protein nitration by nitrotyrosine immunoprecipitation followed by mass spectrometry identified 170 unique nitrated protein candidates involved in 48 biological processes in the knockout mice, compared with the WT. In conclusion, RegIIIβ exerted an important role in the APAP‐induced hepatic protein nitration (NIH DK 53018).

명간보(明肝補) 추출물의 Acetaminophen 유도 간 손상에 대한 보호효과

Objective : Myeongganbo (MGB) composited with Hovenia Semen, Puerariae Radix and Dioscoreae Rhizoma is the prescription for protection of liver function. The purpose of this study was to investigate the effects of MGB extract against acetaminophen (APAP)-induced liver injury in mice. Methods : MGB extract was prepared by extracting with hot distilled water. The extract was freeze-dried following filtration through vacuum distillation system. Mice fasted for overnight were orally administrated with or without MGB extract of different doses (25-200 mg/kg/day). After 30 min, APAP was orally applied with a single dose (400 mg/kg). The levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured in plasmas of mice. Glutathione (GSH), glutathione peroxidase GSH-px), cyclooxygenase-2 (COX-2) activity and tumor necrosis factor-<TEX>${\alpha}$</TEX> (TNF-<TEX>${\alpha}$</TEX>) level were investigated in liver homogenates. Liver sections were stained with haematoxylin & eosin, anti-TNF-<TEX>${\alpha}$</TEX> and anti-mouse COX-2 antibodies. Results : APAP treatment remarkably increased AST and ALT activities in plasma but inhibited GSH and GSH-px levels in liver homogenates. Also, liver injury was significantly accelerated by APAP treatment. Furthermore, APAP remarkably elevated COX-2 activity and TNF-<TEX>${\alpha}$</TEX> levels in liver homogenates. However, administration of MGB extract was able to counteract these effects. Histological studies provided supportive evidence for biochemical and molecular analysis Conclusions : These results suggest that MGB extract has potent hepatoprotective effect against APAP-induced liver injury, these properties may contribute to liver disease care.

Green tea extract supplementation ameliorates CCl4-induced hepatic oxidative stress, fibrosis, and acute-phase protein expression in rat

We evaluated the long-term effects of green tea extract (GTE) supplementation on oxidative stress, biliary acute phase protein expression, and liver function in CCl(4)-induced chronic liver injury. We evaluated the antioxidant activity of GTE in comparison with those of vitamin C, vitamin E, and β-carotene in vitro by using an ultrasensitive chemiluminescence analyzer. Chronic liver injury was induced by intraperitoneally administering carbon tetrachloride (CCl(4)) (1 mL/kg body weight, twice weekly) to female Wistar rats for 8 weeks. The effects of low (4 mg/kg body weight per day) and high (20 mg/kg body weight per day) doses of intragastric GTE on CCl(4)-induced liver dysfunction and fibrosis were examined by measuring the bile and blood reactive oxygen species levels and biochemical parameters by using Western blot and two-dimensional polyacrylamide gel electrophoresis techniques. GTE has greater scavenging activity against O(2)(-), H(2)O(2), and Hypochlorous acid (HOCl) in vitro than vitamin C, vitamin E, and β-carotene do. In vivo, CCl(4) markedly increased bile and blood reactive oxygen species production, lipid accumulation, number of infiltrated leukocytes, fibrosis, hepatic hydroxyproline content, and plasma alanine aminotransferase and aspartate aminotransferase activities, and reduced plasma albumin levels. Two-dimensional polyacrylamide gel electrophoresis revealed that CCl(4) increased the acute-phase expression of six biliary proteins and decreased hepatic B-cell lymphoma 2 (Bcl-2), catalase, and CuZn superoxide dismutase protein expression. GTE supplementation attenuated CCl(4)-enhanced oxidative stress, levels of biochemical parameters, pathology, and acute-phase protein secretion, and preserved antioxidant/antiapoptotic protein expression. GTE supplementation attenuates CCl(4)-induced hepatic oxidative stress, fibrosis, acute phase protein excretion, and hepatic dysfunction via the antioxidant and antiapoptotic defense mechanisms.

Complement Activation in Acetaminophen-Induced Liver Injury in Mice

Overdose with acetaminophen (APAP) results in acute liver failure in humans and experimental animals. Complement comprises more than 30 proteins that can participate in tissue injury and/or repair, but the role of complement activation in APAP-induced hepatotoxicity has not been evaluated. Treatment of male, C57BL6J mice with APAP (200-400 mg/kg) resulted in liver injury as evidenced by increased activity of alanine aminotransferase (ALT) in plasma and hepatocellular necrosis. Plasma concentration of the complement component C3 was significantly reduced 6 h after treatment with APAP, indicating complement activation, and C3b (detected by immunostaining) accumulated in the centrilobular areas of liver lobules. Pretreatment with cobra venom factor (CVF; 15 U/mouse) to deplete complement components abolished APAP-mediated C3b accumulation, and this was accompanied by reductions in plasma ALT activity, hepatocellular necrosis, hepatic neutrophil accumulation, and expression of inflammatory genes (interleukin-6, interleukin-10, and plasminogen activation inhibitor-1) at 24 h after APAP treatment. Loss of hepatocellular GSH was similar in APAP-treated mice pretreated with either saline or CVF, suggesting that CVF pretreatment did not affect APAP bioactivation. Mice with a genetic deficiency in C3 had reduced ALT activity 6 and 12 h after APAP administration compared with wild-type animals. These results reveal a key role for complement activation in hepatic inflammation and progression of injury during the pathogenesis of APAP-induced hepatotoxicity.

Inhibition of Apoptosis Protects Mice from Ethanol‐Mediated Acceleration of Early Markers of CCl4‐Induced Fibrosis but not Steatosis or Inflammation

Correlative evidence indicates that apoptosis is associated with the progression of alcoholic liver disease. If apoptosis contributes to ethanol (EtOH)-induced steatohepatitis and/or fibrosis, then mice deficient in Bid, a key pro-apoptotic Bcl-2 family member, or mice treated with a pan-caspase inhibitor (VX166) should be resistant to EtOH-induced liver injury. This hypothesis was tested in mice using a model of chronic, heavy EtOH-induced liver injury, as well as in a model in which moderate EtOH feeding accelerated the appearance of early markers of hepatic fibrosis in response to acute carbon tetrachloride (CCl(4) ) exposure. Chronic EtOH feeding to mice increased TUNEL- and cytokeratin-18-positive cells in the liver, as well as the expression of receptor-interacting protein kinase 3 (RIP3), a marker of necroptosis. In this model, Bid-/- mice or wild-type mice treated with VX166 were protected from EtOH-induced apoptosis, but not EtOH-induced RIP3 expression. Bid deficiency or inhibition of caspase activity did not protect mice from EtOH-induced increases in plasma alanine and aspartate amino transferase activity, steatosis, or mRNA expression of some inflammatory cytokines. Moderate EtOH feeding to mice enhanced the response of mice to acute CCl(4) exposure, resulting in increased expression of α-smooth muscle actin and accumulation of extracellular matrix protein. VX166-treatment attenuated EtOH-mediated acceleration of these early indicators of CCl(4) -induced hepatic fibrosis, decreasing the expression of α-smooth muscle actin, and the accumulation of extracellular matrix protein. EtOH-induced apoptosis of hepatocytes was mediated by Bid. Apoptosis played a critical role in the accelerating the appearance of early markers of CCl(4) -induced fibrosis by moderate EtOH but did not contribute to EtOH-induced hepatocyte injury, steatosis, or expression of mRNA for some inflammatory cytokines.

Suppressive Effect of High Hydrogen Generating High Amylose Cornstarch on Subacute Hepatic Ischemia-reperfusion Injury in Rats.

We examined whether feeding high hydrogen generating resistant starch could suppress subacute hepatic ischemia-reperfusion injury. Rats were fed a control diet with or without 20% high amylose cornstarch (HAS) supplementation for 14 days. On day 12, rats were subject to ischemia-reperfusion treatment. Portal hydrogen concentration was higher in the HAS group compared with the control group. Increased plasma alanine and aspartate aminotransferase activities due to ischemia-reperfusion treatment tended to decrease, and a significant reduction was observed by HAS feeding when compared with the control group. In conclusion, HAS, which enhances hydrogen generation in the hindgut, alleviated subacute hepatic ischemia-reperfusion injury.

Protective Effects of Berberine on Doxorubicin-Induced Hepatotoxicity in Mice

Doxorubicin, a very potent and often used anti-cancer drug, is largely limited due to the dose-related toxic effects. The present study investigated whether berberine, a natural product alkaloid, can reduce the liver injury induced by doxorubicin. Mice of either gender were randomly divided into four groups: the control group, doxorubicin group, berberine group, and berberine+doxorubicin group. In the tests, body weight, general condition and mortality of the mice were observed, and serum alanine aminotransferase and aspartate transaminase levels were determined to evaluate liver function. Furthermore, the liver was excised for determination of the weight changes, as well as histopathological analysis in the tissues. Mortality rate and significant decline in body weight, and increased plasma alanine aminotransferase and aspartate transaminase activities were observed in doxorubicin-treated mice. These changes were significantly prevented by pretreatment with berberine. Histopathological studies showed that doxorubicin caused structural injuries, such as vascular congestion, inflammatory cell infiltration, hepatocellular degeneration and necrosis, fibrosis in the liver. These histopathological changes were largely attenuated by berberine pretreatment. These findings indicate that berberine has the hepatoprotective effect on doxorubicin-induced liver injury in mice.

Celecoxib, a selective cyclooxygenase-2 inhibitor, lowers plasma cholesterol and attenuates hepatic lipid peroxidation during carbon-tetrachloride–associated hepatotoxicity in rats

Cyclooxygenase-2 (COX-2) expression and prostaglandin production are suggested to play important, complex roles in the pathogenesis of various liver diseases. Studies on the effects of COX-2 inhibitors on the progression of liver fibrosis present controversial results, and the proposed therapeutic potential of these agents in chronic liver disease is predicated largely on their effectiveness in modulating hepatic stellate cell activation in vitro. This study investigated the modulatory effect of celecoxib, a selective COX-2 inhibitor, in CCl4-mediated hepatotoxicity in rats. Thirty Wistar albino rats, weighing 120–180 g, were assigned into five groups of 6 rats/group. Groups 1 and 2 received saline (10 mL/kg) and CCl4 (80 mg/kg), respectively. Group 3 was given celecoxib (5.7 mg/kg), whereas groups 4 and 5 were pretreated with 2.9 and 5.7 mg/kg/day of celecoxib, respectively, 1 hour before CCl4 treatment. Plasma aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase activities increased significantly by 118.5, 150.0, and 51.3%, respectively, with an accompanying decrease (P < 0.05) in total protein and albumin after CCl4 treatment. Hepatotoxicity was associated with a significant increase in plasma cholesterol, hepatic lipid peroxidation (LPO), and severe hepatic necrosis with marked fatty and cellular (i.e., mononuclear cells) infiltration. Although celecoxib neither reduced CCl4-induced increases in marker enzymes of hepatotoxicity nor significantly attenuated hepatic necrosis, it, however, was effective in reducing elevated cholesterol by 16.5 and 20.8% and LPO by 12.9 and 35.5% at 2.9 and 5.7 mg/kg, respectively. Data suggest that COX-2 inhibitors may be effective in controlling hypercholesterolemia and peroxidative changes associated with liver injury.