Long-term ethanol consumption promotes hepatic tumorigenesis but impairs normal hepatocyte proliferation in rats

Pediatric Hepatocellular Adenomas: What Is Known and What Is New?

Current understanding and classification of pediatric hepatocellular adenomas (HCA) are largely based on adult data. HCAs are rare in children and, unlike in adults, are often seen in the context of syndromes or abnormal background liver. Attempts to apply the adult classification to pediatric tumors have led to several "unclassifiable" lesions. Although typically considered benign, few can show atypical features and those with beta-catenin mutations have a risk for malignant transformation. Small lesions can be monitored while larger (>5.0 cm) lesions are excised due to symptoms or risk of bleeding/rupture, etc. Management depends on gender, age, underlying liver disease, multifocality, size of lesion, histologic subtype and presence of mutation, if any. In this review, we summarize the data on pediatric HCAs and highlight our experience with their diagnosis and management.

Profiling the oxylipidome in aged mice after chronic ethanol feeding: Identifying lipid metabolites as drivers of hepatocyte stress

The global population of people over the age of 65 is increasing and expected to reach 1.5 billion by 2050. While aging is associated with a number of chronic illnesses including dementia, the underlying contribution of alcohol misuse in the elderly is understudied. Long-term chronic alcohol misuse can lead to alcohol-associated liver disease, consisting of a spectrum of pathologies, including steatosis and cirrhosis; liver disease can be rapidly accelerated by non-resolving inflammation. Despite this knowledge, the mechanistic underpinnings of dysregulated host immunity and accelerated liver disease progression in the aged by alcohol is unknown. Alcohol misuse in the elderly is on the rise and aging is associated with progressive increases in pro-inflammatory cytokine production. The goals of the current study are to characterize bioactive lipid mediators of inflammation by making use of a murine model of ethanol-induced liver disease in 3-month-old and 20-month-old mice by quantitatively profiling selected oxylipins in liver, brain and plasma. Following chronic ethanol exposure, liver injury, steatosis, and senescence markers were robustly increased in aged mice compared to young adult mice. Expression of proinflammatory cytokines and lipid metabolizing enzymes were increased in liver by both age and ethanol feeding. Lipoxygenase-derived lipid metabolites 9- and 13-hydroxy-octadecadienoic acid and 15-hydroxyeicosatetraenoic acid were increased in liver and plasma in ethanol-fed aged mice and positively correlated with liver injury. In plasma, 9,10-dihydroxy-octadecenoic acid/epoxy-octadecenoic acid plasma ratios correlated with liver injury in ethanol-fed aged mice. Finally, 15-hydroxyeicosatetraenoic acid and 9,10-dihydroxy-octadecenoic acid positively correlated between liver and plasma. Importantly, leukotriene E4, 9,10-dihydroxy-octadecenoic acid and 15-hydroxyeicosatetraenoic acid increased lipid accumulation and ER stress in cultured AML12 hepatocytes. These data highlight the complexity of lipid metabolite networks but identify key mediators that may be used for diagnostic and prognostic markers in early stages of alcohol-related liver disease in patients of all ages.

Developmental trichloroethylene exposure enhances predictive markers of autoimmunity in a sex-specific manner in disease-resistant female mice

Trichloroethylene (TCE) is a widely used industrial chemical and common environmental pollutant. Exposure to TCE promotes CD4⁺ T cell-driven autoimmunity including autoimmune hepatitis (AIH) in both humans and female autoimmune-prone mice. Because the developing immune system is more sensitive during development, we predicted that non- autoimmune-prone, C57/Bl6 (B6) mice would exhibit some autoimmune-related changes using the Developmental Origins of Health and Disease (DOHaD) model of exposure. Both male and female mice were exposed to vehicle or an environmentally relevant dose of 5 μg/ml TCE (0.9 mg/kg/day) beginning at 2 weeks pre-conception and ending at weaning. CD4+ T cells were assessed for phenotypic markers by flow cytometry. An assessment of cytokines elicited ex vivo after 4d polarization from naïve to CD4⁺ T helper subsets (i.e., Th1, Th17, and T reg) was conducted. mRNA expression of liver genes associated with inflammation, regeneration/repair associated with AIH disease progression in autoimmune-prone mice were evaluated by qRT-PCR. The results demonstrated TCE's ability to induce autoimmune- related biomarkers in B6 mice to an even greater degree in females compared to males when exposed during development.

Risk factors for early postoperative recurrence in single and small hepatitis B virus-associated primary hepatocellular carcinoma

Objective

To investigate the risk factors of early postoperative recurrence in patients with single and small (≤3 cm) hepatitis B virus-associated primary hepatocellular carcinoma (HBV-HCC).

Methods

This retrospective study analyzed patients with single and small HBV-HCC. All patients were followed up for 1 year after surgery.

Results

Among 182 patients, 54 patients had early recurrence within 1 year. The recurrence group had higher proportions of men, drinking history, Child–Turcotte–Pugh (CTP) class C, patients who underwent transarterial chemoembolization (TACE), and serum alpha-fetoprotein (AFP) >10 ng/mL as well as higher gamma-glutamyl transpeptidase (GGT) levels and lower total protein (TP) and CD8⁺ T lymphocyte levels than the no recurrence group. Cox multivariate regression analysis demonstrated that drinking history (HR, 1.312; 95% CI, 1.042–1.652), CTP class C (HR, 1.236; 95% CI, 1.037–1.473), TACE treatment (HR, 1.241; 95% CI, 1.026–1.501), GGT (HR, 1.138; 95% CI, 1.042–1.243), TP (HR, 0.729; 95% CI, 0.555–0.957), and AFP (HR, 2.519; 95% CI, 1.343–4.726) were independently associated with early postoperative recurrence.

Conclusion

Drinking history, CTP class C, TACE, serum AFP, GGT, and TP levels were independently associated with early postoperative recurrence in patients with single and small HBV-HCC.

Chronic Low-Dose Alcohol Consumption Attenuates Post-Ischemic Inflammation via PPARγ in Mice

Ischemic stroke is one of the leading causes of death and permanent disability in adults. Recently, we found that light alcohol consumption (LAC) suppresses post-ischemic inflammatory response, which plays an important role in ischemic brain damage. Our goal was to determine the role of peroxisome proliferator-activated receptor-gamma (PPARγ) in the anti-inflammatory effect of LAC against transient focal cerebral ischemia. In in vivo study, male C57BL/6J wild type (WT) and endothelial-specific conditional PPARγ knockout mice were gavage fed with 0.7 g/kg/day ethanol or volume-matched water daily for 8 weeks. From the 7th week, 3 mg/kg/day GW9662 (a selective PPARγ antagonist) was intraperitoneally given for two weeks. Cerebral ischemia/reperfusion (I/R) injury and expression of manganese superoxide dismutase (MnSOD) and adhesion molecules, neutrophil infiltration, and microglial activation in the cerebral cortex before and following a 90 min unilateral middle cerebral artery occlusion (MCAO)/24 h reperfusion were evaluated. In in vitro study, the impact of chronic alcohol exposure on expression of PPARγ and MnSOD in C57BL/6J mouse brain microvascular endothelial cells (MBMVECs) was measured. PPARγ and MnSOD were significantly upregulated in the cerebral cortex of ethanol-fed WT mice and low-concentration ethanol-exposed C57BL/6J MBMVECs. GW9662 significantly inhibited alcohol-induced upregulation of MnSOD. Eight-week ethanol feeding significantly reduced cerebral I/R injury and alleviated the post-ischemic inflammatory response (upregulation of intercellular adhesion molecule-1 (ICAM-1) and E-selectin, microglial activation, and neutrophil infiltration). Treatment with GW9662 and endothelial-specific conditional knockout of PPARγ did not alter cerebral I/R injury and the inflammatory response in the control mice but abolish the neuroprotective effect in ethanol-fed mice. In addition, GW9662 and endothelial-specific conditional knockout of PPARγ diminished the inhibitory effect of LAC on the post-ischemic expression of adhesion molecules and neutrophil infiltration. Our findings suggest that LAC may protect against cerebral I/R injury by suppressing the post-ischemic inflammation via activation of PPARγ.

Sex-Dependent Effects on Liver Inflammation and Gut Microbial Dysbiosis After Continuous Developmental Exposure to Trichloroethylene in Autoimmune-Prone Mice

Trichloroethylene (TCE) is a common environmental toxicant linked with hypersensitivity and autoimmune responses in humans and animal models. While autoimmune diseases are more common in females, mechanisms behind this disparity are not clear. Recent evidence suggests that autoimmunity may be increasing in males, and occupational studies have shown that TCE-mediated hypersensitivity responses occur just as often in males. Previous experimental studies in autoimmune-prone MRL^+/+ mice have focused on responses in females. However, it is important to include both males and females in order to better understand sex-disparity in autoimmune disease. In addition, because of an alarming increase in autoimmunity in adolescents, developmental and/or early life exposures to immune-enhancing environmental pollutants should also be considered. Using MRL^+/+ mice, we hypothesized that TCE would alter markers related to autoimmunity to a greater degree in female mice relative to male mice, and that TCE would enhance these effects. Mice were continuously exposed to either TCE or vehicle beginning at gestation, continuing during lactation, and directly in the drinking water. Both male and female offspring were evaluated at 7 weeks of age. Sex-specific effects were evident. Female mice were more likely than males to show enhanced CD4⁺ T cell cytokine responses (e.g., IL-4 and IFN-γ). Although none of the animals developed pathological or serological signs of autoimmune hepatitis-like disease, TCE-exposed female mice were more likely than males in either group to express higher levels of biomarkers in the liver related to regeneration/repair and proliferation. Levels of bacterial populations in the intestinal ileum were also altered by TCE exposure and were more prominent in females as compared to males. Thus, our expectations were correct in that young adult female mice developmentally exposed to TCE were more likely to exhibit alterations in immunological and gut/liver endpoints compared to male mice.

Independent risk factors for disease recurrence after surgery in patients with hepatitis B virus-related hepatocellular carcinoma ≤3 cm in diameter

Background

Post-operative recurrence rates are high for hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC). This study aimed to explore the factors associated with post-operative 1-year recurrence rate in patients with HBV-related HCC who had a single small primary tumor (≤3 cm in diameter).

Methods

This was a retrospective study of 203 (training cohort) and 64 (validation cohort) patients newly diagnosed with HBV-related HCC who had a single small primary tumor. The first year of post-operative follow-up was examined. Factors potentially associated with HCC recurrence were identified using Cox regression analyses. A model was constructed based on the factors identified and the prognostic value of the model was evaluated using receiver operating characteristic (ROC) curve analysis and calculation of the area under the ROC curve (AUC).

Results

A history of alcoholism and serum levels of α-fetoprotein, total protein and γ-glutamyl transpeptidase (GGT) were independently associated with 1-year recurrence rate after surgery. A predictive model based on these four factors had an AUC of 0.711 (95% confidence interval, 0.643-0.772) in the training cohort and 0.727 (95% confidence interval, 0.601-0.831) in the validation cohort. The 1-year recurrence rate was significantly lower in the low-risk group than in the high-risk group in both the training cohort (17.0% vs. 49.5%, P < 0.001) and the validation cohort (43.2% vs. 74.1%, P = 0.031).

Conclusion

A history of alcoholism and serum levels of α-fetoprotein, total protein and γ-glutamyl transpeptidase were independently associated with post-operative 1-year recurrence rate in patients with HBV-related HCC who had a single small primary tumor (≤3 cm in diameter).

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Inhibition of diethylnitrosamine-initiated alcohol-promoted hepatic inflammation and precancerous lesions by flavonoid luteolin is associated with increased sirtuin 1 activity in mice

BACKGROUND

Chronic and excessive alcohol consumption is an established risk for hepatic inflammation and carcinogenesis. Luteolin is one of the most common flavonoids present in plants and has potential beneficial effects against cancer. In this study, we examined the effect and potential mechanisms of luteolin supplementation in a carcinogen initiated alcohol-promoted pre-neoplastic liver lesion mouse model.

METHODS

C57BL/6 mice were injected with diethylnitrosamine (DEN) [i.p. 25 mg/kg of body weight (BW)] at 14 days of age. At 8 weeks of age mice were group pair-fed with Lieber-DeCarli liquid control diet or alcoholic diet [ethanol (EtOH) diet, 27% total energy from ethanol] and supplemented with a dose of 30 mg luteolin/kg BW per day for 21 days.

RESULTS

DEN-injected mice fed EtOH diet displayed a significant induction of pre-neoplastic lesions, a marker associated with presence of steatosis and inflammation. Dietary luteolin significantly reduced the severity and incidence of hepatic inflammatory foci and steatosis in DEN-injected mice fed EtOH diet, as well the presence of preneoplastic lesions. There was no difference on hepatic protein levels of sirtuin 1 (SIRT1) among all groups; however, luteolin supplementation significantly reversed alcohol-reduced SIRT1 activity assessed by the ratio of acetylated and total forkhead box protein O1 (FoXO1) and SIRT1 target proliferator-activated receptor gamma, coactivator 1 alpha (PGC1α).

CONCLUSIONS

Dietary intake of luteolin prevents alcohol promoted pre-neoplastic lesions, potentially mediated by SIRT1 signaling pathway.

Update on the new classification of hepatic adenomas: clinical, molecular, and pathologic characteristics

CONTEXT

Hepatic adenoma is an uncommon, benign, hepatic neoplasm that typically occurs in women of child-bearing age, often with a history of long-term use of oral contraceptive drugs. This is usually detected as an incidental mass lesion in a noncirrhotic liver during imaging studies. Pathologic evaluation by needle core biopsy remains the gold standard for diagnosis. Molecular studies have revealed that hepatic adenomas involve unique molecular pathways that are distinct from hepatocellular carcinoma. Based on these studies, a French collaborative group has recently proposed a molecular-pathologic classification for hepatic adenomas. In addition, advances in molecular studies have led to reclassification of the "telangiectatic variant of focal nodular hyperplasia" as "hepatic adenoma, inflammatory subtype."

OBJECTIVE

To review the proposed, new classification of hepatic adenoma and the changes in diagnostic workup in light of the above-mentioned developments.

DATA SOURCES

Review of published literature and illustrations from clinical case material.

CONCLUSIONS

Definitive diagnosis of liver mass lesion on needle core biopsies has a decisive role in clinical management. With the advent of the new classification of hepatic adenomas and its prognostic implications, it is vital for pathologists to be aware of the morphologic features seen in different subtypes and the available diagnostic tools, such as immunohistochemistry, to help identify the correct subtype.

The role of reactive oxygen species (ROS) and cytochrome P-450 2E1 in the generation of carcinogenic etheno-DNA adducts

Exocyclic etheno-DNA adducts are mutagenic and carcinogenic and are formed by the reaction of lipidperoxidation (LPO) products such as 4-hydoxynonenal or malondialdehyde with DNA bases. LPO products are generated either via inflammation driven oxidative stress or via the induction of cytochrome P-450 2E1 (CYP2E1). In the liver CYP2E1 is induced by various compounds including free fatty acids, acetone and ethanol. Increased levels of CYP2E1 and thus, oxidative stress are observed in the liver of patients with non-alcoholic steatohepatitis (NASH) as well as in the chronic alcoholic. In addition, chronic ethanol ingestion also increases CYP2E1 in the mucosa of the oesophagus and colon. In all these tissues CYP2E1 correlates significantly with the levels of carcinogenic etheno-DNA adducts. In contrast, in patients with non-alcoholic steatohepatitis (NASH) hepatic etheno-DNA adducts do not correlate with CYP2E1 indicating that in NASH etheno-DNA adducts formation is predominately driven by inflammation rather than by CYP2E1 induction. Since etheno-DNA adducts are strong mutagens producing various types of base pair substitution mutations as well as other types of genetic damage, it is strongly believed that they are involved in ethanol mediated carcinogenesis primarily driven by the induction of CYP2E1.

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Cytochrome P-450 2E1 is induced following chronic ethanol ingestion.

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CYP2E1 correlates with carcinogenic etheno-DNA formation.

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CYP2E1 and oxidative stress are important mechanisms in alcohol mediated carcinogenesis in the liver, undefined and colon.

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In NASH hepatic etheno-DNA adducts occur but possible due to inflammation.

The role of reactive oxygen species (ROS) and cytochrome P-450 2E1 in the generation of carcinogenic etheno-DNA adducts

Exocyclic etheno-DNA adducts are mutagenic and carcinogenic and are formed by the reaction of lipidperoxidation (LPO) products such as 4-hydoxynonenal or malondialdehyde with DNA bases. LPO products are generated either via inflammation driven oxidative stress or via the induction of cytochrome P-450 2E1 (CYP2E1). In the liver CYP2E1 is induced by various compounds including free fatty acids, acetone and ethanol. Increased levels of CYP2E1 and thus, oxidative stress are observed in the liver of patients with non-alcoholic steatohepatitis (NASH) as well as in the chronic alcoholic. In addition, chronic ethanol ingestion also increases CYP2E1 in the mucosa of the oesophagus and colon. In all these tissues CYP2E1 correlates significantly with the levels of carcinogenic etheno-DNA adducts. In contrast, in patients with non-alcoholic steatohepatitis (NASH) hepatic etheno-DNA adducts do not correlate with CYP2E1 indicating that in NASH etheno-DNA adducts formation is predominately driven by inflammation rather than by CYP2E1 induction. Since etheno-DNA adducts are strong mutagens producing various types of base pair substitution mutations as well as other types of genetic damage, it is strongly believed that they are involved in ethanol mediated carcinogenesis primarily driven by the induction of CYP2E1.

Alcoholic liver disease: a synopsis of the Charles Lieber's Memorial Symposia 2009-2012

This paper is based upon the 'Charles Lieber Satellite Symposia' organized by Manuela G. Neuman at each of the 2009-2012 Research Society on Alcoholism (RSA) Annual Meetings. The presentations represent a broad spectrum dealing with alcoholic liver disease (ALD). In addition, a literature search (2008-2013) in the discussed area was performed in order to obtain updated data. The presentations are focused on genetic polymorphisms of ethanol metabolizing enzymes and the role of cytochrome P4502E1 (CYP2E1) in ALD. In addition, alcohol-mediated hepatocarcinogenesis, immune response to alcohol and fibrogenesis in alcoholic hepatitis as well as its co-morbidities with chronic viral hepatitis infections in the presence or absence of human deficiency virus are discussed. Finally, emphasis was led on alcohol and drug interactions as well as liver transplantation for end-stage ALD.

CD36-deficient mice are resistant to alcohol- and high-carbohydrate-induced hepatic steatosis

CD36 is a scavenger receptor with multiple ligands and cellular functions, including facilitating cellular uptake of free fatty acids (FFAs). Chronic alcohol consumption increases hepatic CD36 expression, leading to the hypothesis that this promotes uptake of circulating FFAs, which then serve as a substrate for triglyceride (TG) synthesis and the development of alcoholic steatosis. We investigated this hypothesis in alcohol-fed wild-type and Cd36-deficient (Cd36(-/-)) mice using low-fat/high-carbohydrate Lieber-DeCarli liquid diets, positing that Cd36(-/-) mice would be resistant to alcoholic steatosis. Our data show that the livers of Cd36(-/-) mice are resistant to the lipogenic effect of consuming high-carbohydrate liquid diets. These mice also do not further develop alcoholic steatosis when chronically fed alcohol. Surprisingly, we did not detect an effect of alcohol or CD36 deficiency on hepatic FFA uptake; however, the lower baseline levels of hepatic TG in Cd36(-/-) mice fed a liquid diet were associated with decreased expression of genes in the de novo lipogenesis pathway and a lower rate of hepatic de novo lipogenesis. In conclusion, Cd36(-/-) mice are resistant to hepatic steatosis when fed a high-carbohydrate liquid diet, and they are also resistant to alcoholic steatosis. These studies highlight an important role for CD36 in hepatic lipid homeostasis that is not associated with hepatic fatty acid uptake.

The role of cytochrome P450 2E1 in ethanol-mediated carcinogenesis

We and others have shown that chronic alcohol consumption results in the induction of CYP2E1 in the liver. We have also detected for the first time such an induction in the mucosa of the small intestine and the colon. The overall induction of CYP2E1 shows interindividual variations and occurs already following a daily ingestion of 40 g of ethanol after 1 week. CYP2E1 induction is associated with an increased metabolism of ethanol resulting in the generation of reactive oxygen species (ROS) with direct and indirect carcinogenic action. ROS generated by CYP2E1 may lead to lipid peroxidation and lipid peroxidation products such as 4-hydroxynonenal bind to DNA forming highly carcinogenic exocyclic etheno DNA-adducts. The generation of these adducts has been shown in cell cultures in animal experiments as well as in human liver biopsies. CYP2E1 also metabolizes various procarcinogens present in diets and in tobacco smoke to their carcinogenic metabolites. Among these, nitrosamines seem to be the most important carcinogens. CYP2E1 also degrades retinoic acid and retinol to polar metabolites. Metabolism of retinoic acid not only results in the loss of retinoic acid promoting carcinogenesis through an increase in cell proliferation and dedifferentiation but also in generation of polar metabolites with apoptotic properties. We have shown that chlormethiazole is a specific CYP2E1 inhibitor in humans. Chlormethiazole inhibits CYP2E1 activity and thus blocks the formation of DNA adducts in cell cultures, restores retinoic acids in alcohol fed animals and inhibits chemical induced ethanol mediated hepatocarcinogenesis. Thus, there is increasing evidence that CYP2E1 induced by chronic alcohol consumption plays an important role in alcohol mediated carcinogenesis.

Cytochrome P450 2E1 inhibition prevents hepatic carcinogenesis induced by diethylnitrosamine in alcohol-fed rats

Chronic alcohol ingestion increases hepatic cytochrome P450 2E1 (CYP2E1), which is associated with hepatocarcinogenesis. We investigated whether treatment with chlormethiazole (CMZ), a CYP2E1 inhibitor, protects against alcohol-associated hepatic carcinogenesis in rats. Rats were fed either an ethanol liquid diet or a non-ethanol liquid diet, with or without CMZ for one and ten months. A single intraperitoneal injection of diethylnitrosamine (DEN, 20 mg/kg) was given to initiate hepatic carcinogenesis. CYP2E1 expression, inflammatory proteins, cell proliferation, protein-bound 4-HNE, etheno-DNA adducts, 8-hydroxy-2'-deoxyguanosine (8-OHdG), retinoid concentrations, and hepatic carcinogenesis were examined. Ethanol feeding for 1 month with DEN resulted in significantly increased hepatic CYP2E1 levels and increased nuclear accumulation of NF-κB protein and TNF-α expression, which were associated with increased cyclin D1 expression and p-GST positive altered hepatic foci. All of these changes induced by ethanol feeding were significantly inhibited by the one month CMZ treatment. At 10-months of treatment, hepatocellular adenomas were detected in ethanol-fed rats only, but neither in control rats nor in animals receiving ethanol and CMZ. The 8-OHdG formation was found to be significantly increased in ethanol fed animals and normalized with CMZ treatment. In addition, alcohol-reduced hepatic retinol and retinoic acid concentrations were restored by CMZ treatment to normal levels in the rats at 10 months of treatment. These data demonstrate that the inhibition of ethanol-induced CYP2E1 as a key pathogenic factor can counteract the tumor-promoting action of ethanol by decreasing TNF-α expression, NF-κB activation, and oxidative DNA damage as well as restoring normal hepatic levels of retinoic acid in DEN-treated rats.

Low-dose alcohol consumption protects against transient focal cerebral ischemia in mice: possible role of PPARγ

Background

We examined the influence of low-dose alcohol consumption on cerebral ischemia/reperfusion (I/R) injury in mice and a potential mechanism underlying the neuroprotective effect of low-dose alcohol consumption.

Methodology/Principal Findings

C57BL/6 J mice were fed a liquid diet without or with 1% alcohol for 8 weeks, orally treated with rosiglitazone (20 mg/kg/day), a peroxisome proliferator-activated receptor gamma (PPARγ)-selective agonist, or GW9662 (3 mg/kg/day), a selective PPARγantagonist, for 2 weeks. The mice were subjected to unilateral middle cerebral artery occlusion (MCAO) for 90 minutes. Brain injury, DNA fragmentation and nuclear PPARγ protein/activity were evaluated at 24 hours of reperfusion. We found that the brain injury and DNA fragmentation were reduced in 1% alcohol-fed mice compared to nonalcohol-fed mice. Rosiglitazone suppressed the brain injury in nonalcohol-fed mice, but didn't alter the brain injury in alcohol-fed mice. In contrast, GW9662 worsened the brain injury in alcohol-fed mice, but didn't alter the brain injury in nonalcohol-fed mice. Nuclear PPARγ protein/activity at peri-infarct and the contralateral corresponding areas of the parietal cortex was greater in alcohol-fed mice compared to nonalcohol-fed mice. Using differentiated catecholaminergic (CATH.a) neurons, we measured dose-related influences of chronic alcohol exposure on nuclear PPARγ protein/activity and the influence of low-dose alcohol exposure on 2-hour oxygen-glucose deprivation (OGD)/24-hour reoxygenation-induced apoptosis. We found that low-dose alcohol exposure increased nuclear PPARγ protein/activity and protected against the OGD/reoxygenation-induced apoptosis. The beneficial effect of low-dose alcohol exposure on OGD/reoxygenation-induced apoptosis was abolished by GW9662.

Conclusions/Significance

Our findings suggest that chronic consumption of low-dose alcohol protects the brain against I/R injury. The neuroprotective effect of low-dose alcohol consumption may be related to an upregulated PPARγ.