4-hydroxy-2-nonenal and Liver-Diseases

Reactive oxygen intermediates (ROI) and other pro-oxidant agents are known to elicit, in vivo and in vitro, oxidative decomposition of omega-3 and omega-6 polyunsaturated fatty acids of membrane phospholipids (i.e, lipid peroxidation). This leads to the formation of a complex mixture of aldehydic end-products, including malonyldialdehyde (MDA), 4-hydroxy-2,3-nonenal (HNE), and other 4-hydroxy-2,3-alkenals (HAKs) of different chain length. These aldehydic molecules have been considered originally as ultimate mediators of toxic effects elicited by oxidative stress occurring in biological material. Experimental and clinical evidence coming from different laboratories now suggests that HNE and HAKs can also act as bioactive molecules in either physiological and pathological conditions. These aldehydic compounds can affect and modulate, at very low and nontoxic concentrations, several cell functions, including signal transduction, gene expression, cell proliferation, and, more generally, the response of the target cell(s). In this review article, we would like to offer an up-to-date review on this particular aspect of oxidative stress--dependent modulation of cellular functions-as well as to offer comments on the related pathophysiological implications, with special reference to human conditions of disease.

Topics: Aldehydes; Arteriosclerosis; Chemotactic Factors; Chronic Disease; Humans; Inflammation; Liver Diseases; Nervous System Diseases; Oxidative Stress; Proteins; Reperfusion Injury; Signal Transduction

Hepatic ischemia/reperfusion injury (HIRI) is a complex pathophysiological process that often leads to poor clinical prognosis. Clinically, the effective means to alleviate HIRI are limited. The aim of the present study was to investigate whether Alda‑1, an activator of mitochondrial aldehyde dehydrogenase 2 (ALDH2), had a protective effect on HIRI and to investigate the mechanisms underlying this protective effect. Sprague‑Dawley rats were treated with Alda‑1 or Daidzin, an ALDH2 inhibitor, 30 min before partial (70%) warm liver ischemia to induce HIRI. The 48 rats were randomly divided into four groups: Sham, ischemia injury (IR), IR‑Alda‑1, and IR‑Daidzin. After 6 and 24 h of reperfusion, serum and liver tissue samples were collected and stored for further experiments. Alanine aminotransferase, aspartate aminotransferase and hematoxylin & eosin staining was used to evaluate the liver damage. Western blotting and reverse transcription‑quantitative PCR were used to detect the expression of related proteins and mRNA. TUNEL staining was used to observe the apoptosis of liver cells. Transmission electron microscopy was used to detect the mitochondrial injuries. Alda‑1 pretreatment ameliorated the HIRI‑induced damage to the liver function and reduced histological lesions. Alda‑1 also increased ALDH2 activity after HIRI. Moreover, the pretreatment with Alda‑1 reduced the accumulation of toxic aldehyde 4‑hydroxy‑2‑nonenal, decreased the production of reactive oxygen species and malondialdehyde, reversed the damage to the liver mitochondria, attenuated hepatocyte apoptosis and inhibited the HIRI‑induced inflammatory response, including high‑mobility group box 1/toll‑like receptor 4 signaling. Alda‑1 also induced autophagy by upregulating autophagy‑related 7 and Rab7 increasing the microtubule associated protein 1 light chain 3 αII/I ratio and inhibiting p62 expression. ALDH2‑induced autophagy was dependent on the activation of the AKT/mammalian target of rapamycin (mTOR) and AMP‑activated protein kinase (AMPK) signaling pathways. In conclusion, the findings of the present study suggested that Alda‑1 may protect the liver against HIRI‑induced damage, including hepatic enzyme injury, acetaldehyde accumulation, oxidative stress, hepatocyte apoptosis and inflammation. Alda‑1 may confer this protection by inducing autophagy through the AKT/mTOR and AMPK signaling pathways. Therefore, ALDH2 could represent a potential pharmacological target in the clinical treatment

Topics: Aldehydes; Animals; Autophagy; Benzamides; Benzodioxoles; Disease Models, Animal; Gene Expression Regulation; Liver Diseases; Liver Function Tests; Male; Oxidative Stress; Random Allocation; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Reperfusion Injury

Ischemia-reperfusion (IR) injury is a major clinical problem and is associated with numerous adverse effects. GGsTop [2-amino-4{[3-(carboxymethyl)phenyl](methyl)phosphono}butanoic acid] is a highly specific and irreversible γ-glutamyl transpeptidase (γ-GT) inhibitor. We studied the protective effects of GGsTop on IR-induced hepatic injury in rats. Ischemia was induced by clamping the portal vein and hepatic artery of left lateral and median lobes of the liver. Before clamping, saline (IR group) or saline containing 1 mg/kg body wt of GGsTop (IR-GGsTop group) was injected into the liver through the inferior vena cava. At 90 min of ischemia, blood flow was restored. Blood was collected before induction of ischemia and prior to restoration of blood flow and at 12, 24, and 48 h after reperfusion. All the animals were euthanized at 48 h after reperfusion and the livers were harvested. Serum levels of alanine transaminase, aspartate transaminase, and γ-GT were significantly lower after reperfusion in the IR-GGsTop group compared with the IR group. Massive hepatic necrosis was present in the IR group, while only few necroses were present in the IR-GGsTop group. Treatment with GGsTop increased hepatic GSH content, which was significantly reduced in the IR group. Furthermore, GGsTop prevented increase of hepatic γ-GT, malondialdehyde, 4-hydroxynonenal, and TNF-α while all these molecules significantly increased in the IR group. In conclusion, treatment with GGsTop increased glutathione levels and prevented formation of free radicals in the hepatic tissue that led to decreased IR-induced liver injury. GGsTop could be used as a pharmacological agent to prevent IR-induced liver injury and the related adverse events.

Topics: Alanine Transaminase; Aldehydes; Aminobutyrates; Animals; Aspartate Aminotransferases; Cytoprotection; Disease Models, Animal; Enzyme Inhibitors; gamma-Glutamyltransferase; Glutathione; Interleukin-1beta; Liver; Liver Diseases; Male; Malondialdehyde; Necrosis; Organophosphonates; Oxidative Stress; Rats, Wistar; Reperfusion Injury; Tumor Necrosis Factor-alpha

The aim of the study was to investigate the in vitro antioxidant properties Moringa oleifera Lam. (MO) extracts and its curative role in acetaminophen (APAP)-induced toxic liver injury in rats caused by oxidative damage. The total phenolic content and antioxidant properties of hydroethanolic extracts of different MO edible parts were investigated by employing an established in vitro biological assay. In the antihepatotoxic study, either flowers or leaves extract (200 mg/kg or 400 mg/kg, i.p) were administered an hour after APAP administration, respectively. N-Acetylcysteine was used as the positive control against APAP-induced hepatotoxicity. The levels of liver markers such as alanine aminotransferase (ALT) and the levels of oxidative damage markers including malondialdehyde (MDA), 4-hydroxynonenal (4-HNE) protein adduct, reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) were analysed and compared between experimental groups. Among MO edible parts the flower extracts contain the highest total phenolic content and antioxidant capacity, followed by leaves extract. The oxidative marker MDA, as well as 4-HNE protein adduct levels were elevated and GSH, SOD and CAT were significantly decreased in groups treated with hepatotoxin. The biochemical liver tissue oxidative markers measured in the rats treated with MO flowers and leaves hydroethanolic extracts showed a significant (p < 0.05) reduction in the severity of the liver damage. The results of this study strongly indicate the therapeutic properties of MO hydroethanolic extracts against acute liver injury and thereby scientifically support its traditional use.

Topics: Acetaminophen; Aldehydes; Animals; Antioxidants; Biomarkers; Biphenyl Compounds; Ethanol; Flowers; Fluorescence Recovery After Photobleaching; Free Radical Scavengers; Glutathione; Liver; Liver Diseases; Liver Function Tests; Male; Malondialdehyde; Moringa oleifera; Oxidative Stress; Phenols; Phytotherapy; Picrates; Plant Extracts; Rats; Rats, Sprague-Dawley; Water

Hepatocyte cell death is a characteristic indication in the development of non-alcoholic steatohepatitis (NASH); however, the underlying mechanism is still unclear. In this study, we examined the potential mechanism(s) involved in the development of liver injury using a methionine-choline deficient (MCD) diet feeding NASH model. Male C57BL6/J mice were fed MCD and methionine-choline sufficient (MCS) diet for two weeks before being killed. Our results showed that MCD diet feeding resulted in fatty liver and liver injury, evidenced by increased hepatic triglyceride (TG), plasma alanine aminotransferases and hepatic thiobarbituric acid reactive substances levels in MCD-fed mice. Furthermore, we found that MCD diet feeding caused remarkable suppression of hepatic extracellular signal-regulated kinases (ERK) 1/2 activation and increased transforming growth factor (TGF)-beta1 levels in plasma and the liver tissue. In vitro investigations showed that intracellular MEK/ERK1/2 activation status played a critical role in the determination of sensitivity of hepatocytes to TGF-beta1-induced cell death. HepG2 cells, otherwise resistant to TGF-beta1 killing due to high level of ERK1/2 activation, was sensitized by U0126, a specific MEK/ERK1/2 inhibitor, to TGF-beta1 cytotoxicity. H4IIEC3 cells, which have lower level of constitutive ERK1/2 activity, are sensitive to TGF-beta1-induced cell death. Lastly, we demonstrated that administration of epidermal growth factor, a strong ERK1/2 activator, to MCD-fed mice attenuated liver injury without affecting hepatic TG accumulation. Our findings demonstrated that hepatic ERK1/2 inactivation aggravates TGF-beta1-induced hepatotoxicity, which may contribute, at least in part, to the initiation of liver injury in NASH.

Topics: Aldehydes; Animals; Cell Line; Choline Deficiency; Cysteine Proteinase Inhibitors; Enzyme Activation; Epidermal Growth Factor; Humans; Lipid Peroxidation; Liver Diseases; Male; Methionine; Mice; Mice, Inbred C57BL; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Rats; Signal Transduction; Transforming Growth Factor beta1

Oxidant stress is critically involved in various liver diseases. Superoxide formation causes c-Jun NH2-terminal kinase (JNK)- and caspase-dependent apoptosis in cultured hepatocytes. To verify these findings in vivo, male Fisher rats were treated with diquat and menadione. The oxidant stress induced by both compounds was confirmed by increased formation of glutathione disulfide and 4-hydroxynonenal protein adducts. Plasma alanine aminotransferase activities increased from 46+/-4 U/l in controls to 955+/-90 U/l at 6 h after diquat treatment. Hematoxylin and eosin staining of liver sections revealed large areas of necrotic cells at 3 and 6 h. DNA strandbreaks, evaluated with the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay, showed clusters of TUNEL-positive cells, where the staining was predominantly cytosolic and the cells were swollen, indicating oncotic necrosis. There was no significant increase in caspase-3 activities or relevant release of DNA fragments into the cytosol at any time between 0 and 6 h after diquat treatment. Despite the activation of JNK after high doses of diquat, the JNK inhibitor SP-600125 did not protect against diquat-induced necrosis. Menadione alone did not cause liver injury, but, in combination with phorone and FeSO4, induced moderate oncotic necrosis. On the other hand, if animals were treated with galactosamine/endotoxin as positive control for apoptosis, caspase-3 activities were increased by 259%, the number of TUNEL-positive cells with apoptotic morphology was increased 103-fold, and DNA fragmentation was enhanced 6-fold. The data indicate that liver cell death initiated by diquat-induced superoxide formation in vivo is mediated predominantly by oncotic necrosis and is independent of JNK activation.

Topics: Alanine Transaminase; Aldehydes; Animals; Antifibrinolytic Agents; Apoptosis; Caspases; Chemical and Drug Induced Liver Injury; Diquat; Disease Models, Animal; DNA Fragmentation; Endotoxins; Galactosamine; Glutathione Disulfide; Hepatocytes; In Situ Nick-End Labeling; JNK Mitogen-Activated Protein Kinases; Liver Diseases; Male; Necrosis; Oxidative Stress; Rats; Rats, Inbred F344; Superoxides; Vitamin K 3

4-Hydroxynonenal (HNE) is a putative pro-fibrogenic product of oxidative stress able to elicit apoptosis and cytotoxicity in several cell types. This study has been performed to evaluate its 'in vivo' levels in injured liver and whether HNE may induce apoptosis and/or affect selected phenotypic responses in activated human hepatic stellate cells (HSC/MF).. During the development of acute liver injury induced by CCl(4), liver tissue HNE levels were in the range 0.5-10 microM, as shown by high performance liquid chromatography analysis. Cultured human HSC/MF, developed cytotoxicity only if exposed to very high HNE concentrations (25-50 microM) without any sign of induction of classic, caspase-dependent apoptosis, as assessed by evaluating morphology and biochemical parameters of cell death. HNE, at non-cytotoxic doses, up-regulated procollagen type I and tissue inhibitor of metalloproteinases-1 gene expression and/or protein synthesis without significantly affecting chemotaxis (wound healing and haptotaxis assay), matrix metalloproteinases 1 and 2 mRNA expression and activity as well as basal DNA synthesis.. HNE, at concentrations compatible with those detected in vivo, does not elicit HSC/MF classic apoptosis but, rather, may act as a potent pro-fibrogenic stimulus for the expression of genes involved in excess extracellular matrix deposition and proposed as survival signals for HSC/MF.

Topics: Actins; Acute Disease; Aldehydes; Animals; Apoptosis; Carbon Tetrachloride; Cell Death; Cells, Cultured; Chemical and Drug Induced Liver Injury; Cytoskeleton; Dose-Response Relationship, Drug; Extracellular Matrix; Gene Expression; Humans; Liver; Liver Cirrhosis; Liver Diseases; Male; Osmolar Concentration; Phenotype; Rats; Rats, Wistar; Signal Transduction

Liver injury caused by iron overload is presumed to involve lipid peroxidation and the formation of products such as 4-hydroxynonenal (4HNE), which has been implicated in hepatic fibrogenesis. Cellular antioxidants that modulate the formation and detoxification of compounds such as 4HNE may represent important protective mechanisms involved in the response to iron overload. This study examines the relationship between 4HNE, collagen content, and antioxidant defenses in the livers of rats fed carbonyl iron for 10 weeks. Iron-loading resulted in significant increases in iron (8.8-fold), 4HNE (1.7-fold), and hydroxyproline (1.5-fold). Total glutathione content was unchanged by iron, but gamma-glutamyl transpeptidase activity (GGT) increased sixfold and CuZn superoxide dismutase (CuZnSOD) activity decreased >9%. GGT colocalized with iron deposition and was associated with increased GGT mRNA. Decreased CuZnSOD activity was paralleled by a reduction in CuZnSOD protein on Western blot and immunohistochemistry, but no decrease in CuZnSOD mRNA. Glutathione S-transferase (GST) and Mn superoxide dismutase (MnSOD) activities were also significantly increased by iron loading. These results demonstrate that iron overload significantly alters the expression of antioxidant enzymes associated with glutathione (GGT and GST) and superoxide metabolism (CuZnSOD and MnSOD). Furthermore, the localized induction of GGT may enhance detoxification of lipid peroxidation-derived aldehydes via glutathione-dependent pathways in iron-loaded hepatocytes. These alterations in antioxidant defenses may represent an adaptive response, limiting accumulation 4HNE, and thus, stimulation of collagen synthesis, accounting for the mild fibrogenic response seen in this model of iron overload.

Topics: Aldehydes; Animals; Catalase; gamma-Glutamyltransferase; Glutathione; Glutathione Peroxidase; Glutathione Transferase; Immunohistochemistry; Iron Overload; Lipid Peroxidation; Liver Diseases; Male; Rats; Rats, Sprague-Dawley; RNA, Messenger; Superoxide Dismutase

4-Hydroxy-2,3-nonenal (HNE) is an aldehydic end product of lipid peroxidation which has been detected in vivo in clinical and experimental conditions of chronic liver damage. HNE has been shown to stimulate procollagen type I gene expression and synthesis in human hepatic stellate cells (hHSC) which are known to play a key role in liver fibrosis. In this study we investigated the molecular mechanisms underlying HNE actions in cultured hHSC. HNE, at doses compatible with those detected in vivo, lead to an early generation of nuclear HNE-protein adducts of 46, 54, and 66 kD, respectively, as revealed by using a monoclonal antibody specific for HNE-histidine adducts. This observation is related to the lack of crucial HNE-metabolizing enzymatic activities in hHSC. Kinetics of appearance of these nuclear adducts suggested translocation of cytosolic proteins. The p46 and p54 isoforms of c-Jun amino-terminal kinase (JNKs) were identified as HNE targets and were activated by this aldehyde. A biphasic increase in AP-1 DNA binding activity, associated with increased mRNA levels of c-jun, was also observed in response to HNE. HNE did not affect the Ras/ERK pathway, c-fos expression, DNA synthesis, or NF-kappaB binding. This study identifies a novel mechanism linking oxidative stress to nuclear signaling in hHSC. This mechanism is not based on redox sensors and is stimulated by concentrations of HNE compatible with those detected in vivo, and thus may be relevant during chronic liver diseases.

Topics: Aldehydes; Calcium-Calmodulin-Dependent Protein Kinases; Cells, Cultured; Genes, fos; Genes, jun; Histidine; Humans; JNK Mitogen-Activated Protein Kinases; Lipid Peroxidation; Liver; Liver Cirrhosis; Liver Diseases; MAP Kinase Kinase 4; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinase Kinases; Mitogen-Activated Protein Kinases; Molecular Weight; Oxidative Stress; Protein Kinases; Signal Transduction; Transcription Factor AP-1

Lipid peroxidation is an autocatalytic mechanism leading to oxidative destruction of cellular membranes. The deleterious consequences of this mechanism are related in part to the formation of reactive aldehydic products that bind to intra- or extracellular molecules to form adducts. Specific antibodies directed against malondialdehyde (MDA) and 4-hydroxynonenal (HNE) adducts, major aldehydic metabolites of lipid peroxidation, allowed us to investigate in situ, with an immunohistochemical procedure, the occurrence of lipid peroxidation in a panel of different chronic liver diseases. Intracellular HNE and MDA adducts were detected respectively in 24 of 39 cases (62%) and in 12 of 34 cases investigated (35%). They were localized mainly in the cytoplasm of hepatocytes, with the strongest staining observed in hemochromatosis, Wilson's disease, and in areas of acute alcoholic hepatitis in cases of alcoholic liver diseases. A peculiar pattern of immunostaining was observed in primary biliary cirrhosis where biliary cells of destroyed but also intact bile ducts strongly expressed HNE adducts. The liver extracellular matrix also displayed MDA adducts (30 of 34 cases, 88%) and HNE adducts (23 of 39 cases, 59%). While HNE adducts were specifically localized on large bundles of collagen fibers, MDA adducts were detected in a thin reticular network and in sinusoidal cells around portal tracts or fibrous septa. In conclusion, lipid peroxidation by-products are detectable in chronic liver diseases. Immunohistochemical results suggest that this mechanism is implicated very early in the pathogenesis of some of these diseases.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Aldehydes; Animals; Child; Child, Preschool; Chronic Disease; Cytoplasm; Extracellular Matrix; Female; Humans; Immunohistochemistry; Infant; Lipid Peroxidation; Liver; Liver Diseases; Male; Malondialdehyde; Middle Aged; Rats; Retrospective Studies

4-Hydroxy-trans-2-nonenal (HNE) is a highly reactive product of lipid peroxidation originating from the break-down of phospholipid-bound polyunsaturated fatty acids of cellular membranes. Despite its biological relevance, this aldehyde is only occasionally determined due to the complexity of previously described procedures. Here we present a simple and very sensitive method for the detection of HNE in biological samples. The method is based on the measurement of the 2,4-dinitrophenylhydrazone (DNPH) of the aldehyde by electrochemical detection after separation by reverse-phase high-performance liquid chromatography (HPLC). The greater sensitivity of this procedure as compared to the ultraviolet detection method commonly employed to measure DNPH derivatives of aldehydes after HPLC will allow the detection of HNE below the pmol level. The detection of HNE is highly reproducible even in normal tissues and cells. Increased amounts of HNE were detected in the livers of animals intoxicated with prooxidant agents such as carbon tetrachloride, bromotrichloromethane or bromobenzene. An exponential increase in HNE (and in malondialdehyde) was measured in peroxidizing liver microsomes (in the NADPH/Fe-dependent system). The method is also suitable for the study of very small samples, since HNE could be detected in approximately 1 million cultured cells (polyoma virus-transformed baby hamster kidney fibroblasts); the level rose after exposure of the cells to a Fe3+/ADP prooxidant system.

Topics: Aldehydes; Animals; Bromobenzenes; Bromotrichloromethane; Carbon Tetrachloride; Cell Line; Chemical and Drug Induced Liver Injury; Chromatography, High Pressure Liquid; Cricetinae; Electrochemistry; Kidney; Lipid Peroxidation; Liver; Liver Diseases; Male; Malondialdehyde; Mice; Microsomes, Liver; Rats

It is well established that chronic ethanol ingestion enhances lipid peroxidation in the liver in vivo and in vitro. The relationship of lipid peroxidation and protein adduct formation to morphologically assessed liver damage remains problematic. To help determine if a relationship exists between lipid peroxidation and liver pathology rats were fed ethanol and a high fat diet by continuous intragastric tube feeding for 72 days, maintaining the blood alcohol levels above 200 mg/dl. This model induced a fatty liver with focal necrosis and fibrosis. This pathology was associated with an increased total cytochrome P450, an increased cytochrome P450 2E1 isoenzyme (CYP2E1), a decrease in the NADPH-cytochrome P450 reductase activity, an increased rate of NADPH oxidation and an increased NADPH-dependent lipid peroxidation in liver microsomes compared to controls. Serum protein adducts with malondialdehyde 4-hydroxynonenal were significantly increased. Thus, the alcohol-induced liver pathology was associated with the induction of CYP2EI, lipid peroxidation, and protein adduct formation. When isoniazid (INH) in therapeutic doses was fed to rats with ethanol these parameters were changed in that central-central bridging fibrosis was increased, as was lipid peroxidation, whereas INH reduced the ethanol-induced decrease in the reductase, the increase in total P450 and CYP2EI, as well as the NADPH oxidation rate and the elevation of serum transaminase levels. The results tend to link central-central bridging fibrosis with increased lipid peroxidation and aldehyde-protein adduct formation caused by ethanol.

Topics: Aldehydes; Animals; Blood Proteins; Cytochrome P-450 Enzyme System; Dietary Fats; Dose-Response Relationship, Drug; Ethanol; Isoniazid; Lipid Metabolism; Lipid Peroxidation; Liver; Liver Diseases; Male; Malondialdehyde; Microscopy, Electron; Microsomes, Liver; NADP; Oxidoreductases, N-Demethylating; Rats; Rats, Wistar; Transaminases