Induction Of Cytochrome P450 2E1 Research Articles

Targeting of CYP2E1 by miRNAs in alcohol-induced intestine injury

Although binge alcohol-induced gut leakage has been studied extensively in the context of reactive oxygen species (ROS)-mediated signaling, it was recently revealed that post-transcriptional regulation plays an essential role as well. Ethanol (EtOH)-inducible cytochrome P450-2E1 (CYP2E1), a key enzyme in EtOH metabolism, promotes alcohol-induced hepatic steatosis and inflammatory liver disease, at least in part by mediating changes in intestinal permeability. For instance, gut leakage and elevated intestinal permeability to endotoxins have been shown to be regulated by enhancing CYP2E1 mRNA and CYP2E1 protein levels. Although it is understood that EtOH promotes CYP2E1 induction and activation, the mechanisms that regulate CYP2E1 expression in the context of intestinal damage remain poorly defined. Specific miRNAs, including miR-132, miR-212, miR-378, and miR-552, have been shown to repress the expression of CYP2E1, suggesting that these miRNAs contribute to EtOH-induced intestinal injury. Here, we have shown that CYP2E1 expression is regulated post-transcriptionally through miRNA-mediated degradation, as follows: 1) the RNA-binding protein AU-binding Factor 1 (AUF1) binds mature miRNAs, including CYP2E1-targeting miRNAs, and this binding modulates the degradation of corresponding target mRNAs upon EtOH treatment; 2) the Serine/Threonine kinase MST1 mediates oxidative stress-induced phosphorylation of AUF1. Those findings suggest that ROS-mediated signaling modulates AUF1/miRNA interaction through MST1-mediated phosphorylation. Thus, our study demonstrates the critical functions of AUF1 phosphorylation by MST1 in the decay of miRNAs targeting CYP2E1, the stabilization of CYP2E1 mRNA in the presence of EtOH, and the relationship of this pathway to subsequent intestinal injury.

Acetaminophen-Induced Hepatotoxicity in Obesity and Nonalcoholic Fatty Liver Disease: A Critical Review.

The epidemic of obesity, type 2 diabetes and nonalcoholic liver disease (NAFLD) favors drug consumption, which augments the risk of adverse events including liver injury. For more than 30 years, a series of experimental and clinical investigations reported or suggested that the common pain reliever acetaminophen (APAP) could be more hepatotoxic in obesity and related metabolic diseases, at least after an overdose. Nonetheless, several investigations did not reproduce these data. This discrepancy might come from the extent of obesity and steatosis, accumulation of specific lipid species, mitochondrial dysfunction and diabetes-related parameters such as ketonemia and hyperglycemia. Among these factors, some of them seem pivotal for the induction of cytochrome P450 2E1 (CYP2E1), which favors the conversion of APAP to the toxic metabolite N-acetyl-p-benzoquinone imine (NAPQI). In contrast, other factors might explain why obesity and NAFLD are not always associated with more frequent or more severe APAP-induced acute hepatotoxicity, such as increased volume of distribution in the body, higher hepatic glucuronidation and reduced CYP3A4 activity. Accordingly, the occurrence and outcome of APAP-induced liver injury in an obese individual with NAFLD would depend on a delicate balance between metabolic factors that augment the generation of NAPQI and others that can mitigate hepatotoxicity.

Toxic effect of carpet dust on the biochemical indices and histological structure of the lung in rats: the potential role of cytochrome P450 2E1 and extracellular signal-regulated kinase/mitogen-activated protein kinase pathways

Background: Carpet dust exposure in the carpet industry causes various respiratory hazards that lead to permanent loss of lung function. This study investigated the potentially toxic effects of knotted and tufted carpet dust on rat lungs and the possible involvement of cytochrome P450 2E1 (CYP2E1) and extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathways in the induced toxicity, as well as histological changes in the lung induced by carpet dust. Methods: This study divided 48 adult rats into six groups: group I was the control group, group II (vehicle group) received phosphate buffer saline (50 µL/rat), groups III and IV received knotted dust (2.5 and 5 mg/kg, respectively), and groups V and VI received tufted dust (2.5 and 5 mg/kg, respectively). All treatments were intranasally administered once a day for 7 days. Results: Both dust types significantly decreased the lung content of GSH compared with the control. Significantly elevated malondialdehyde (MDA) and nitric oxide (NO) lung contents were observed with an increased CYP2E1, interleukin (IL)-6, nuclear factor kappa B (NF-κβ), and ERK/MAPK. The histological lung structure was moderately affected with a moderately increased number of CD68-positive macrophages in the lung parenchyma of knotted dust-exposed rats, whereas tufted dust exposure severely affected the lung tissue with significantly increased CD68-positive macrophages. Conclusions: Carpet dust exposure could induce oxidative stress and inflammatory response in the lung tissue via induction of CYP2E1 that stimulates ERK/MAPK signalling pathway proteins, resulting in elevated MDA, NO and IL-6 levels in the lung tissue with suppressed GSH content. Tufted dust could possess a more toxic response than knotted ones.

Fasting Enhances the Acute Toxicity of Acrylonitrile in Mice via Induction of CYP2E1.

Cytochrome P450 2E1 (CYP2E1) plays an essential role in the susceptibility to acute acrylonitrile (AN)-induced toxicity. Here, we investigated the toxicity and mechanism of AN in fasting mice and potential underlying mechanisms. Convulsions, loss of righting reflex, and death 4 h after AN treatment were observed and recorded for each group of mice. Relative to ad lib-fed mice, 48 h fasting significantly increased the acute toxicity of AN, as noted by a more rapid onset of convulsions and death. In addition, fasting significantly enhanced CYP2E1-mediated oxidative metabolism of AN, resulting in increased formation of CN- (one of the end-metabolites of AN). Moreover, fasting decreased hepatic GSH content, abrogating the detoxification of GSH. However, trans-1,2-dichloroethylene (DCE), a CYP2E1 inhibitor, altered the level of hepatic CYP2E1 activity in response to fasting, reduced the acute toxic symptoms of AN and the content of CN- in AN-treated mice. These data establish that fasting predisposes to AN toxicity, attributable to induced CYP2E1 and reduced hepatic GSH.

Alcohol induced hepatic retinoid depletion is associated with the induction of multiple retinoid catabolizing cytochrome P450 enzymes.

Chronic alcohol consumption leads to a spectrum of liver disease that is associated with significant global mortality and morbidity. Alcohol is known to deplete hepatic vitamin A content, which has been linked to the pathogenesis of alcoholic liver disease. It has been suggested that induction of Cytochrome P450 2E1 (CYP2E1) contributes to alcohol-induced hepatic vitamin A depletion, but the possible contributions of other retinoid-catabolizing CYPs have not been well studied. The main objective of this study was to better understand alcohol-induced hepatic vitamin A depletion and test the hypothesis that alcohol-induced depletion of hepatic vitamin A is due to CYP-mediated oxidative catabolism. This hypothesis was tested in a mouse model of chronic alcohol consumption, including wild type and Cyp2e1 -/- mice. Our results show that chronic alcohol consumption is associated with decreased levels of hepatic retinol, retinyl esters, and retinoic acid. Moreover, the depletion of hepatic retinoid is associated with the induction of multiple retinoid catabolizing CYPs, including CYP26A1, and CYP26B1 in alcohol fed wild type mice. In Cyp2e1 -/- mice, alcohol-induced retinol decline is blunted but retinyl esters undergo a change in their acyl composition and decline upon alcohol exposure like WT mice. In conclusion, the alcohol induced decline in hepatic vitamin A content is associated with increased expression of multiple retinoid-catabolizing CYPs, including the retinoic acid specific hydroxylases CYP26A1 and CYP26B1.

Hepatoprotection by Ginsenoside Rg1 in alcoholic liver disease

Alcoholic hepatitis (AH) has caused serious mortality to the world’s population. Despite tremendous efforts to reduce disease burden, effective treatments for this disease are still lacking. Ginsenoside Rg1 (G-Rg1) has been reported to be hepatoprotective in several liver injury models. However, therapeutic potential of this drug in AH has not been tested. In this study, using a chronic ethanol-feeding model, we found that ethanol-fed mice presented clinical indicators of liver injury, such as elevated serum levels of alanine transaminase (ALT), aspartate aminotransferase (AST) and total bilirubin (Tbil), as well as development of hepatic steatosis. Upon treatment with G-Rg1, animals showed marked decreases in serum biochemical parameters, as well as improvement in liver histology. Mechanistically, G-Rg1 blocked the induction of cytochrome P4502E1 (CYP2E1), and prevented the generation of reactive oxygen species (ROS), mitochondria damage, as well as hepatocellular apoptosis. As a result, NLRP3 inflammasome activation was inhibited, which subsequently suppressed the production of active caspase-1 and inflammatory cytokines. Our data has demonstrated a hepatoprotective role for G-Rg1 in AH, and identified potential drugable pathways to improve disease outcomes. These findings may have significant implications for developing novel therapies for inflammatory liver diseases.

Expression of type I collagen in response to Isoniazid exposure is indirect and is facilitated by collateral induction of cytochrome P450 2E1: An in-vitro study.

We wanted to investigate whether Isoniazid (INH) can directly stimulate activation of hepatic stellate cells (HSCs) and enhance production of collagen. Treatment of human hepatic stellate cell line LX2 with or without 5μM INH for 24 to 72 hours was performed to look into content of cytochrome P450 2E1 (CYP2E1), activity of NADPH oxidase (NOX) and intracellular oxidative stress. Protein level as well as mRNA expression of alpha smooth muscle actin (α-SMA) and collagen1A1 (COL1A1) were assessed by western blot and real time PCR. In some experiments pyrazole (PY) was pre-treated to LX2 cells to induce CYP2E1 prior to INH treatment. CYP2E1 level as well as NOX activity was gradually increased with INH treatment in LX2 cells till 72 hours. Following 72 hours of INH exposure, intracellular glutathione (GSH) level was found to be reduced compared to control (p<0.01) and showed expression of α-SMA, indicating activation of HSC. We could not found any change in collagen expression in this experimental study. Pyrazole (PY) pre-treatment to LX2 cells caused significant increase in cellular CYP2E1 content associated with increase of NOX, intracellular reactive oxygen species (ROS), and expression of α-SMA and collagen1 after INH exposure. CYP2E1 is present in insignificant amount in HSCs and INH treatment could not induce collagen expression, although altered cellular oxidant levels was observed. But in LX2 cells when CYP2E1 was over-expressed by PY, INH administration provokes oxidative stress mediated stellate cells activation along with collagen type I expression.

Role of Alcohol Drinking in Alzheimer's Disease, Parkinson's Disease, and Amyotrophic Lateral Sclerosis.

Neurodegenerative diseases, including Alzheimer’s disease (AD), Parkinson’s disease (PD) and amyotrophic lateral sclerosis (ALS), increase as the population ages around the world. Environmental factors also play an important role in most cases. Alcohol consumption exists extensively and it acts as one of the environmental factors that promotes these neurodegenerative diseases. The brain is a major target for the actions of alcohol, and heavy alcohol consumption has long been associated with brain damage. Chronic alcohol intake leads to elevated glutamate-induced excitotoxicity, oxidative stress and permanent neuronal damage associated with malnutrition. The relationship and contributing mechanisms of alcohol with these three diseases are different. Epidemiological studies have reported a reduction in the prevalence of Alzheimer’s disease in individuals who drink low amounts of alcohol; low or moderate concentrations of ethanol protect against β-amyloid (Aβ) toxicity in hippocampal neurons; and excessive amounts of ethanol increase accumulation of Aβ and Tau phosphorylation. Alcohol has been suggested to be either protective of, or not associated with, PD. However, experimental animal studies indicate that chronic heavy alcohol consumption may have dopamine neurotoxic effects through the induction of Cytochrome P450 2E1 (CYP2E1) and an increase in the amount of α-Synuclein (αSYN) relevant to PD. The findings on the association between alcohol consumption and ALS are inconsistent; a recent population-based study suggests that alcohol drinking seems to not influence the risk of developing ALS. Additional research is needed to clarify the potential etiological involvement of alcohol intake in causing or resulting in major neurodegenerative diseases, which will eventually lead to potential therapeutics against these alcoholic neurodegenerative diseases.

Susceptibility to the acute toxicity of acrylonitrile in streptozotocin-induced diabetic rats: protective effect of phenethyl isothiocyanate, a phytochemical CYP2E1 inhibitor

Diabetes mellitus is a significant global public health issue. The diabetic state not only precipitates chronic disease but also has the potential to change the toxicity of drugs and chemicals. Acrylonitrile (AN) is a potent neurotoxin widely used in industrial products. This study used a streptozotocin (STZ)-induced diabetic rat model to examine the role of cytochrome P450 2E1 (CYP2E1) in acute AN toxicity. The protective effect of phenethyl isothiocyanate (PEITC), a phytochemical inhibitor of CYP2E1, was also investigated. A higher incidence of convulsions and loss of the righting reflex, and decreased rates of survival, as well as elevated CYP2E1 activity, were observed in diabetic rats treated with AN when compared to those in non-diabetic rats, suggesting that diabetes confers susceptibility to the acute toxicity of AN. Pretreatment with PEITC (20–80 mg/kg) followed by AN injection alleviated the acute toxicity of AN in diabetic rats as evidenced by the decreased incidence of convulsions and loss of righting reflex, and increased rates of survival. PEITC pretreatment at 40 and 80 mg/kg decreased hepatic CYP2E1 activity in AN-exposed diabetic rats. PEITC pretreatment (20 mg/kg) increased the glutathione (GSH) content and glutathione S-transferase (GST) activity and further decreased ROS levels in AN-exposed diabetic rats. Collectively, STZ-induced diabetic rats were more sensitive to AN-induced acute toxicity mainly due to CYP2E1 induction, and PEITC pretreatment significantly alleviated the acute toxicity of AN in STZ-induced diabetic rats. PEITC might be considered as a potential effective chemo-preventive agent against AN-induced acute toxicity in individuals with an underlying diabetic condition.

The role of Cytochrom P4502E1 in Alcoholic Liver Disease and alcohol mediated carcinogenesis

Various factors are involved in the pathogenesis of alcoholic liver disease (ALD) and ethanol-mediated carcinogenesis. In addition to genetic, epigenetic and immunologic mechanisms, acetaldehyde-associated toxicity, oxidative stress as well as cytokine-mediated inflammation are of major importance. Oxidative stress, with the generation of reactive oxygen species (ROS), develops either in inflammation (alcoholic hepatitis) or during oxidation of ethanol via cytochrome P4502E1 (CYP2E1). CYP2E1 is induced by ethanol, oxidizes ethanol to acetaldehyde, and generates ROS during this process. ROS results in protein damage, enhanced fibrogenesis and DNA lesions. Furthermore, CYP2E1 induction results in an enhanced activation of various procarcinogens and an increased degradation of retinol and retinoic acid (RA), a compound responsible for cell differentiation and proliferation. An inhibition of CYP2E1 results in an improvement of ALD and chemically induced carcinogenesis in animal experiments. In humans, CYP2E1 is induced following the consumption of 40grams of ethanol per day after one week. However, the induction varies inter-individually. The mechanism for this is still unclear. Patients with ALD show a significant correlation between CYP2E1, the occurrence of highly carcinogenic etheno DNA adducts and the severity of fibrosis. First results on the effect of CYP2E1 inhibition by chlormethiazole, a specific CYP2E1 inhibitor on ALD, can be expected soon.

Tomato lycopene prevention of alcoholic fatty liver disease and hepatocellular carcinoma development

Alcoholic liver disease (ALD) is a major cause of morbidity and mortality worldwide. The incidence of hepatocellular carcinoma (HCC) is increasing in the United States, and chronic, excessive alcohol consumption is responsible for 32%–45% of all the liver cancer cases in the United States. Avoidance of chronic or excessive alcohol intake is the best protection against alcohol-related liver injury; however, the social presence and addictive power of alcohol are strong. Induction of the cytochrome P450 2E1 (CYP2E1) enzyme by chronic and excessive alcohol intake is known to play a role in the pathogenesis of ALD. High intake of tomatoes, rich in the carotenoid lycopene, is associated with a decreased risk of chronic disease. The review will overview the prevention of ALD and HCC through dietary tomato rich in lycopene as an effective intervention strategy and the crucial role of CYP2E1 induction as a molecular target. The review also indicates a need for caution among individuals consuming both alcohol and high dose lycopene as a dietary supplement.

Carcinogenic Etheno DNA Adducts in Alcoholic Liver Disease: Correlation with Cytochrome P-4502E1 and Fibrosis.

One mechanism by which alcoholic liver disease (ALD) progresses is oxidative stress and the generation of reactive oxygen species, among others due to the induction of cytochrome P-4502E1 (CYP2E1). Experimental data underline the key role of CYP2E1 because ALD could be partially prevented in rats by the administration of the specific CYP2E1 inhibitor chlormethiazole. As CYP2E1 is linked to the formation of carcinogenic etheno DNA adducts in ALD patients, a causal role of alcohol-induced CYP2E1 in hepatocarcinogenesis is implicated. The purpose of this study was to investigate CYP2E1 induction in ALD, and its correlation with oxidative DNA lesions and with hepatic histology. Hepatic biopsies from 97 patients diagnosed with ALD were histologically scored for steatosis, inflammation, and fibrosis. CYP2E1 and the exocyclic etheno DNA adduct 1,N6 -etheno-2'deoxyadenosine (εdA) were determined immunohistochemically. In addition, in 42 patients, 8-hydroxydeoxyguanosine (8-OHdG) was also evaluated using immunohistochemistry. A significant positive correlation was found between CYP2E1 and εdA (p<0.0001) as well as between CYP2E1 and 8-OHdG (p=0.039). Both CYP2E1 (p=0.0094) and ɛdA (p<0.0001) also correlated significantly with the stage of hepatic fibrosis. Furthermore, a significant correlation between the fibrosis stage and the grade of lobular inflammation (p<0.0001) was observed. However, the amount of alcohol consumed did not correlate with any of the parameters determined. These data suggest an important role of CYP2E1 in the generation of εdA, in the fibrotic progression of ALD, and thus in alcohol-mediated hepatocarcinogenesis. CYP2E1 may be a target in the treatment of ALD and a potential prognostic marker for disease progression.

The induction of cytochrome P450 2E1 by ethanol leads to the loss of synaptic proteins via PPARα down-regulation.

Ethanol, one of the most commonly abused substances throughout history, is a substrate and potent inducer of cytochrome P450 2E1 (CYP2E1). Our previous study showed that brain CYP2E1 was induced by chronic ethanol treatment and was associated with ethanol-induced neurotoxicity in rats. We therefore investigated the possible mechanism of brain CYP2E1 involvement in ethanol-induced neurodegeneration. Compared with the controls, chronic ethanol treatment (3.0g/kg, i.g., 160days) significantly increased CYP2E1 mRNA levels in the rat cortex, but the mRNA levels of peroxisome proliferator-activated receptor α (PPARα) and the pre- and post-synaptic proteins (synaptophysin, SYP, and drebrin1, DBN1) were decreased. Ethanol treatment dose-dependently induced CYP2E1 mRNA expression, and CYP2E1 overexpression exacerbated the ethanol-induced neurotoxicity. Pretreatment with p38 inhibitor (SB202190) and ERK1/2 inhibitor (U0126) attenuated the induction of CYP2E1 mRNA and protein levels by ethanol; however, no change was observed with JNK inhibitor pretreatment. Ethanol exposure or CYP2E1 overexpression significantly decreased PPARα, SYP, and DBN1 expression as indicated by the data from real-time RT-PCR, Western blotting and immunocytochemistry. The activation of PPARα by WY14643 increased the activity of the SYP and DBN1 promoters and attenuated the inhibition of these genes by ethanol. The specific siRNA for CYP2E1 significantly attenuated the ethanol-induced inhibition of PPARα, SYP and DBN1 mRNA levels. These results suggest that the induction of CYP2E1 by ethanol may be mediated via the p38 and ERK1/2 signaling pathways in neurons but not via the JNK pathway. The CYP2E1-PPARα axis may play a role in ethanol-induced neurotoxicity via the alteration of the genes related with synaptic function.

Cytochrome P450 2E1 increases the sensitivity of hepatoma cells to vitamin K2.

Although vitamin K2 (VK2) exhibits inhibitory effects on the viability of hepatoma cells, hepatoma cells are insensitive to VK2. Therefore, this investigation is an attempt to enhance the sensitivity of hepatoma cells to VK2. Our results showed that VK2 acted synergistically with ethanol (EtOH) to inhibit the viability of Smmc-7721 cells, mainly because cytochrome P4502E1 (CYP2E1) was activated by EtOH. The synergistic effect of VK2 and EtOH was also observed in QGY-7703 cells, which also express CYP2E1. However, in HepG2 cells, which do not express CYP2E1, the synergistic effect of VK2 and EtOH was not observed. In addition, we demonstrated that CYP2E1 could be induced by VK2 via both post-transcriptional and transcriptional mechanisms. These results suggest that induction of CYP2E1 can enhance the inhibitory effect of VK2 on the viability of hepatoma cells. CYP2E1 may be an attractive target for enhanced antitumor effects of VK2 in hepatocellular carcinoma treatment.

Carcinogenic Etheno DNA-Adducts in Alcoholic Liver Disease: Correlation with Cytochrome P-450 and Fibrosis

Background & Aims: One mechanism by which alcoholic liver disease (ALD) progresses from pure fatty liver to fibrosis and cirrhosis is oxidative stress and the generation of reactive oxygen species (ROS), predominantly due to the induction of cytochrome P-4502E1 (CYP2E1). Experimental data underline the key role of CYP2E1 since ALD could be partially prevented in rats by the administration of the specific CYP2E1 inhibitor chlormethiazole. Since CYP2E1 is responsible for the formation of carcinogenic etheno DNA-adducts in man and since CYP2E1 inhibition in rats results in a significant reduction of hepatic adenomas, a causal role of alcohol induced CYP2E1 in hepatocarcinogenesis has been recognized. The purpose of this study was to investigate CYP2E1 induction in ALD and to correlate CYP2E1 with various DNA lesions and histological parameters including hepatic fat, inflammation, fibrosis.

The Alcohol Intolerance Produced by Isoniazid Is Not Due to a Disulfiram-Like Reaction Despite Aldehyde Dehydrogenase Inhibition

Background/Aims: Isoniazid (ISO) has been reported to inhibit the hepatic aldehyde dehydrogenase (ALDH) and to cause a disulfiram (DIS)-like reaction, albeit there are no reports demonstrating increased blood acetaldehyde levels after co-administration of ISO with alcohol. The aim of our study was to clarify whether the alcohol intolerance produced by ISO is indeed due to a typical DIS-like reaction. Methods: DIS and ISO were administered to Wistar rats and the hepatic ethanol (ETH) metabolizing enzyme activities along with the levels of brain monoamines were determined. Blood acetaldehyde levels were also evaluated after co-administration of ETH with DIS or ISO. Results: Despite inhibition of the hepatic ALDH, ISO did not result in elevated blood acetaldehyde levels after ETH administration, probably due to the induction of cytochrome P450 2E1 which theoretically leads to an increased elimination rate of acetaldehyde preventing its accumulation. Moreover, ISO produced some minor, but statistically significant, alterations in central monoaminergic neurotransmission. Conclusion: Our results demonstrate for the first time that despite ALDH inhibition ISO does not provoke a typical DIS-like reaction since it does not increase blood acetaldehyde levels after co-administration with ETH. The possibility that the ETH intolerance observed in ISO treatment is a central synergistic effect cannot be excluded.

Repeated administration of ethambutol in therapeutic dose causes testes alteration and spermatogenesis disruption in Wistar rats.

Ethambutol (EMB) is conventionally used to treat tuberculosis and atypical Mycobacterium infections in combination with other antimycobacterial drugs. Eventually, EMB testicular toxicity has not been explored extensively yet. The aim of the study is to evaluate testicular toxicity of EMB. We explored the impact of EMB on male rats' fertility, testosterone level and germ cells state, testicular pro- and anti-oxidant status and DNA damage, as well as identified EMB effects on cytochrome P-450 2E1 (CYP2E1) both with computer simulation and in vivo. We demonstrated that EMB administration to male rats decreased in epididymal sperm count (19%) and fertility index (53%). These events were accompanied by reduction in serum testosterone content (1.6 times) and appearance of spermatogenic epithelium damages. It was also found in testes the intensification of lipid peroxidation, decrease in reduced glutathione content and changes in DNA fragmentation. Additionally, computer simulation showed direct interaction of EMB with CYP2E1 active site and heme. On the top of this, we demonstrated that level of testicular CYP2E1 messenger RNA in EMB-treated rats was increased 8.7 folds and p-nitrophenol hydroxylase activity in testes rose three folds. As this shows, EMB-caused CYP2E1 induction, oxidative stress, and apoptosis in the testes contribute to inhibition of steroidogenesis enzymes and spermatogenesis disruption.

Optimal management for alcoholic liver disease: Conventional medications, natural therapy or combination?

Alcohol consumption is the principal factor in the pathogenesis of chronic liver diseases. Alcoholic liver disease (ALD) is defined by histological lesions on the liver that can range from simple hepatic steatosis to more advanced stages such as alcoholic steatohepatitis, cirrhosis, hepatocellular carcinoma and liver failure. As one of the oldest forms of liver injury known to humans, ALD is still a leading cause of liver-related morbidity and mortality and the burden is exerting on medical systems with hospitalization and management costs rising constantly worldwide. Although the biological mechanisms, including increasing of acetaldehyde, oxidative stress with induction of cytochrome p450 2E1, inflammatory cytokine release, abnormal lipid metabolism and induction of hepatocyte apoptosis, by which chronic alcohol consumption triggers serious complex progression of ALD is well established, there is no universally accepted therapy to prevent or reverse. In this article, we have briefly reviewed the pathogenesis of ALD and the molecular targets for development of novel therapies. This review is focused on current therapeutic strategies for ALD, including lifestyle modification with nutrition supplements, available pharmacological drugs and new agents that are under development, liver transplantation, application of complementary medicines, and their combination. The relevant molecular mechanisms of each conventional medication and natural agent have been reviewed according to current available knowledge in the literature. We also summarized efficacy vs safety on conventional and herbal medicines which are specifically used for the prevention and treatment of ALD. Through a system review, this article highlighted that the combination of pharmaceutical drugs with naturally occurring agents may offer an optimal management for ALD and its complications. It is worthwhile to conduct large-scale, multiple centre clinical trials to further prove the safety and benefits for the integrative therapy on ALD.

A cellular model to study drug-induced liver injury in nonalcoholic fatty liver disease: Application to acetaminophen

Obesity and nonalcoholic fatty liver disease (NAFLD) can increase susceptibility to hepatotoxicity induced by some xenobiotics including drugs, but the involved mechanisms are poorly understood. For acetaminophen (APAP), a role of hepatic cytochrome P450 2E1 (CYP2E1) is suspected since the activity of this enzyme is consistently enhanced during NAFLD. The first aim of our study was to set up a cellular model of NAFLD characterized not only by triglyceride accumulation but also by higher CYP2E1 activity. To this end, human HepaRG cells were incubated for one week with stearic acid or oleic acid, in the presence of different concentrations of insulin. Although cellular triglycerides and the expression of lipid-responsive genes were similar with both fatty acids, CYP2E1 activity was significantly increased only by stearic acid. CYP2E1 activity was reduced by insulin and this effect was reproduced in cultured primary human hepatocytes. Next, APAP cytotoxicity was assessed in HepaRG cells with or without lipid accretion and CYP2E1 induction. Experiments with a large range of APAP concentrations showed that the loss of ATP and glutathione was almost always greater in the presence of stearic acid. In cells pretreated with the CYP2E1 inhibitor chlormethiazole, recovery of ATP was significantly higher in the presence of stearate with low (2.5mM) or high (20mM) concentrations of APAP. Levels of APAP-glucuronide were significantly enhanced by insulin. Hence, HepaRG cells can be used as a valuable model of NAFLD to unveil important metabolic and hormonal factors which can increase susceptibility to drug-induced hepatotoxicity.

Hyperlipidemia exacerbates cerebral injury through oxidative stress, inflammation and neuronal apoptosis in MCAO/reperfusion rats.

Recent studies showed that hyperglycemia enhanced brain damage when subjected to transient cerebral ischemic stroke. However, the etiologic link between them has been less known. In the present study, based on an experimental rat's model of hyperlipidemia combined with cerebral ischemia-reperfusion injury (I/R), we herein showed that hyperlipidemia induced by high-fat diet (HFD) resulted in considerable increase in serum triglycerides, cholesterol and low-density lipoprotein cholesterol, and remarkable decrease in serum high-density lipoprotein cholesterol, which associated with an exacerbation on neurological deficit, cerebral infarct and terminal deoxynucleotidyl transferase-mediated nick end labeling-positive cells in the ischemic hemisphere of cerebral I/R rats treated with HFD diet. The data showed that serum superoxide dismutase activity and glutathione peroxides content were significantly decreased, while malondialdehyde level was obviously increased by hyperlipidemia or cerebral I/R alone, especially by coexistence of hyperlipidemia and cerebral I/R; meantime, hyperlipidemia also enhanced cerebral I/R-induced protein expression of cytochrome P450 2E1 (CYP2E1) and the levels of pro-inflammatory factors tumor necrosis factor-α and IL-6 in the ischemic hemispheres. Furthermore, the combined action of hyperlipidemia and cerebral I/R resulted in a protein increase expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 compared to hyperlipidemia or cerebral I/R alone. Meanwhile, this study also showed that hyperlipidemia significantly enhanced cerebral I/R-induced transfer of cytochrome c from mitochondria to cytosolic and the protein expressions of Apaf-1 and caspase-3, but also decreased cerebral I/R-induced bcl-2 protein expression. The results reveal that hyperlipidemia exacerbates cerebral I/R-induced injury through the synergistic effect on CYP2E1 induction, which further induces reactive oxygen species formation, oxidative stress, inflammation and neuronal apoptosis by coexistence of hyperlipidemia and cerebral I/R.