Role of CYP2E1 in ethanol-induced oxidant stress, fatty liver and hepatotoxicity

Solanum nigrum L. berries extract ameliorated the alcoholic liver injury by regulating gut microbiota, lipid metabolism, inflammation, and oxidative stress

Solanum nigrum L. (SN) berry is an edible berry containing abundant polyphenols and bioactive compounds, which possess antioxidant and antiinflammatory properties. However, the effects of SN on alcohol-induced biochemical changes in the enterohepatic axis remain unclear. In the current study, a chronic ethanol-fed mice ALD model was used to test the protective mechanisms of SN berries. Microbiota composition was determined via 16S rRNA sequencing, we found that SN berries extract (SNE) improved intestinal imbalance by reducing the Firmicutes to Bacteroides ratio, restoring the abundance of Akkermansia microbiota, and reducing the abundance of Allobaculum and Shigella. SNE restored the intestinal short-chain fatty acids content. In addition, liver transcriptome data analysis revealed that SNE primarily affected the genes involved in lipid metabolism and inflammatory responses. Furthermore, SNE ameliorated hepatic steatosis in alcohol-fed mice by activating AMP-activated protein kinase (AMPK), acetyl-CoA carboxylase (ACC), peroxisome proliferator-activated receptor α (PPAR-α). SNE reduced the expression of toll-like receptor 4 (TLR4), myeloid differentiation factor-88 (MyD88) nuclear factor kappa-B (NF-κB), which can indicate that SNE mainly adjusted LPS/TLR4/MyD88/NF-κB pathway to reduce liver inflammation. SNE enhanced hepatic antioxidant capacity by regulating NRF2-related protein expression. SNE alleviates alcoholic liver injury by regulating of gut microbiota, lipid metabolism, inflammation, and oxidative stress. This study may provide a reference for the development and utilization of SN resources.

Modest effect of differential dietary vitamin A intake on the pathogenesis of alcohol-associated liver disease

BACKGROUND

Chronic alcohol consumption is a major public health issue. The primary organ damaged by alcohol abuse is the liver, leading to alcohol-associated liver disease (ALD). ALD begins with hepatic steatosis and can progress to fibrosis and cirrhosis; however, we have an incomplete understanding of ALD pathogenesis. Interestingly, the liver is also the major organ for vitamin A metabolism and storage, and ALD has previously been linked with altered hepatic vitamin A homeostasis. We hypothesize that alcohol-induced vitamin A depletion disrupts its normal function in the liver, contributing to the pathogenesis of ALD. To test this hypothesis, we postulated that adding copious vitamin A to the diet might alleviate ALD, and conversely, that a vitamin A deficient diet would worsen ALD.

METHODS

We conducted two dietary intervention studies in mice comparing deficient (0 IU/g diet) and copious (25 IU/g diet) dietary vitamin A intake versus control (4 IU/g diet), using the NIAAA chronic-binge model of ALD. Hepatic steatosis was assessed using histopathological and biochemical approaches. Tissue Vitamin A levels were measured using high-performance liquid chromatography. Markers of ALD, hepatic inflammation and lipid metabolism were analyzed by the quantitative polymerase chain reaction and western blotting.

RESULTS

As expected, a 0 IU/g Vitamin A diet decreased, and a 25 IU/g Vitamin A diet increased hepatic Vitamin A stores. However, alcohol induced changes in hepatic triglyceride levels, markers of hepatic lipid metabolism, inflammation and fibrosis were not significantly different in mice consuming a copious or deficient vitamin A diet compared to control.

CONCLUSIONS

Altered vitamin A intake and hepatic vitamin A storage have a minor effect on the pathogenesis of ALD. Thus, given the known link between altered retinoic acid signaling and ALD, future studies that further explore this linkage are warranted.

Contributing roles of mitochondrial dysfunction and hepatocyte apoptosis in liver diseases through oxidative stress, post-translational modifications, inflammation, and intestinal barrier dysfunction

This review provides an update on recent findings from basic, translational, and clinical studies on the molecular mechanisms of mitochondrial dysfunction and apoptosis of hepatocytes in multiple liver diseases, including but not limited to alcohol-associated liver disease (ALD), metabolic dysfunction-associated steatotic liver disease (MASLD), and drug-induced liver injury (DILI). While the ethanol-inducible cytochrome P450-2E1 (CYP2E1) is mainly responsible for oxidizing binge alcohol via the microsomal ethanol oxidizing system, it is also responsible for metabolizing many xenobiotics, including pollutants, chemicals, drugs, and specific diets abundant in n-6 fatty acids, into toxic metabolites in many organs, including the liver, causing pathological insults through organelles such as mitochondria and endoplasmic reticula. Oxidative imbalances (oxidative stress) in mitochondria promote the covalent modifications of lipids, proteins, and nucleic acids through enzymatic and non-enzymatic mechanisms. Excessive changes stimulate various post-translational modifications (PTMs) of mitochondrial proteins, transcription factors, and histones. Increased PTMs of mitochondrial proteins inactivate many enzymes involved in the reduction of oxidative species, fatty acid metabolism, and mitophagy pathways, leading to mitochondrial dysfunction, energy depletion, and apoptosis. Unique from other organelles, mitochondria control many signaling cascades involved in bioenergetics (fat metabolism), inflammation, and apoptosis/necrosis of hepatocytes. When mitochondrial homeostasis is shifted, these pathways become altered or shut down, likely contributing to the death of hepatocytes with activation of inflammation and hepatic stellate cells, causing liver fibrosis and cirrhosis. This review will encapsulate how mitochondrial dysfunction contributes to hepatocyte apoptosis in several types of liver diseases in order to provide recommendations for targeted therapeutics.

Melatonin Prevents Alcohol- and Metabolic Dysfunction- Associated Steatotic Liver Disease by Mitigating Gut Dysbiosis, Intestinal Barrier Dysfunction, and Endotoxemia

Melatonin (MT) has often been used to support good sleep quality, especially during the COVID-19 pandemic, as many have suffered from stress-related disrupted sleep patterns. It is less known that MT is an antioxidant, anti-inflammatory compound, and modulator of gut barrier dysfunction, which plays a significant role in many disease states. Furthermore, MT is produced at 400-500 times greater concentrations in intestinal enterochromaffin cells, supporting the role of MT in maintaining the functions of the intestines and gut-organ axes. Given this information, the focus of this article is to review the functions of MT and the molecular mechanisms by which it prevents alcohol-associated liver disease (ALD) and metabolic dysfunction-associated steatotic liver disease (MASLD), including its metabolism and interactions with mitochondria to exert its antioxidant and anti-inflammatory activities in the gut-liver axis. We detail various mechanisms by which MT acts as an antioxidant, anti-inflammatory compound, and modulator of intestinal barrier function to prevent the progression of ALD and MASLD via the gut-liver axis, with a focus on how these conditions are modeled in animal studies. Using the mechanisms of MT prevention and animal studies described, we suggest behavioral modifications and several exogenous sources of MT, including food and supplements. Further clinical research should be performed to develop the field of MT in preventing the progression of liver diseases via the gut-liver axis, so we mention a few considerations regarding MT supplementation in the context of clinical trials in order to advance this field of research.

Wnt-β-catenin in hepatobiliary homeostasis, injury, and repair

Wnt-β-catenin signaling has emerged as an important regulatory pathway in the liver, playing key roles in zonation and mediating contextual hepatobiliary repair after injuries. In this review, we will address the major advances in understanding the role of Wnt signaling in hepatic zonation, regeneration, and cholestasis-induced injury. We will also touch on some important unanswered questions and discuss the relevance of modulating the pathway to provide therapies for complex liver pathologies that remain a continued unmet clinical need.

Alcohol-induced liver injury in signalling pathways and curcumin's therapeutic potential

Confronting the profound public health concern of alcohol-induced liver damage calls for inventive therapeutic measures. The social, economic, and clinical ramifications are extensive and demand a comprehensive understanding. This thorough examination uncovers the complex relationship between alcohol intake and liver damage, with a special emphasis on the pivotal roles of the Toll-like receptor 4 (TLR4)/NF-κB p65 and CYP2E1/ROS/Nrf2 signalling networks. Different alcohol consumption patterns, determined by a myriad of factors, have significant implications for liver health, leading to a spectrum of adverse effects. The TLR4/NF-κB p65 pathway, a principal regulator of inflammation and immune responses, significantly contributes to various disease states when its balance is disrupted. Notably, the TLR4/MD-2-TNF-α pathway has been linked to non-alcohol related liver disease, while NF-κB activation is associated with alcohol-induced liver disease (ALD). The p65 subunit of NF-κB, primarily responsible for the release of inflammatory cytokines, hastens the progression of ALD. Breakthrough insights suggest that curcumin, a robust antioxidant and anti-inflammatory compound sourced from turmeric, effectively disrupts the TLR4/NF-κB p65 pathway. This heralds a new approach to managing alcohol-induced liver damage. Initial clinical trials support curcumin's therapeutic potential, highlighting its ability to substantially reduce liver enzyme levels. The narrative surrounding alcohol-related liver injury is gradually becoming more intricate, intertwining complex signalling networks such as TLR4/NF-κB p65 and CYP2E1/ROS/Nrf2. The protective role of curcumin against alcohol-related liver damage marks the dawn of new treatment possibilities. However, the full realisation of this promising therapeutic potential necessitates rigorous future research to definitively understand these complex mechanisms and establish curcumin's effectiveness and safety in managing alcohol-related liver disorders.

Detoxification activity of bioactive food compounds against ethanol-induced injuries and hangover symptoms: A review

Alcohol drinking is a popular activity among adolescents in many countries, largely due to its pleasant, relaxing effects. As a major concern, ethanol consumption put the drinkers at risk of nutrients' deficiency due to the disordered eating, anorexia, and malabsorption of nutrients. Moreover, alcohol drinking may lead to the development of hangover symptoms including diarrhea, thirsty, fatigue, and oxidative stress. A broad range of functional food components with antioxidant and/or anti-inflammatory properties including pectin, aloe vera polysaccharides, chito-oligosaccharides, and other herbal components have been explored due to their detoxification effects against ethanol. The underlying anti-hangover mechanisms include reducing the intestinal absorption of ethanol or its metabolites, increasing the activity of ethanol metabolizing enzymes, development of fatty acid β-oxidation in mitochondria, inhibition of inflammatory response, blocking the target receptors of ethanol in the body, and possession of antioxidant activity under the oxidative stress developed by ethanol consumption. Therefore, the development of bioactive food-based therapeutic formula can assist clinicians and also drinkers in the alleviation of alcohol side effects.

Experimental models of fatty liver diseases: Status and appraisal

Fatty liver diseases, including alcohol-associated liver disease (ALD) and nonalcoholic fatty liver disease nonalcoholic fatty liver disease (NAFLD), affect a large number of people worldwide and become one of the major causes of end-stage liver disease, such as liver cirrhosis and hepatocellular carcinoma (HCC). Unfortunately, there are currently no approved pharmacological treatments for ALD or NAFLD. This situation highlights the urgent need to explore new intervention targets and discover effective therapeutics for ALD and NAFLD. The lack of properly validated preclinical disease models is a major obstacle to the development of clinical therapies. ALD and NAFLD models have been in the development for decades, but there are still no models that recapitulate the full spectrum of ALD and NAFLD. Throughout this review, we summarize the current in vitro and in vivo models used for research on fatty liver diseases and discuss the advantages and limitations of these models.

Serum interleukin-4 is elevated in clinical drug-induced liver injury

BACKGROUND

Drug-induced liver injury (DILI) remains a challenging diagnosis due to an absence of specific biomarkers. DILI due to volatile anaesthetics (VA-DILI) is characterised by trifluoroacetyl and CYP2E1 antibodies, but may not be seen for weeks after injury. Interleukin-4 (IL-4) may be involved in the production of these antibodies and may serve as a clinically useful early biomarker of VA-DILI.

AIM

To prospectively compare serum IL-4 levels between patients who develop VA-DILI and controls following exposure to the volatile anaesthetic.

METHODS

A nested case-control study of patients exposed to VA during surgery was conducted. Thirteen DILI cases were identified from the original cohort, and 26 controls were matched according to age, sex and VA agent. Serum samples were collected before and 48-96 h after VA exposure, and analysed for IL-4 using quantitative enzyme-linked immunosorbent assay techniques.

RESULTS

There was a statistically significant difference in serum IL-4 in post-VA samples between DILI cases and controls (control: 0.030 pg/mL, IQR: 0.030 - 0.030 pg/mL vs DILI: 0.044 pg/mL, IQR: 0.030 - 0.061 pg/mL; p = 0.039). A greater proportion of DILI cases had post-VA IL-4 levels above the assay lower limit of detection compared to controls (control: 23% vs DILI: 69%; p = 0.013).

CONCLUSION

IL-4 is a potential biomarker of DILI. Clinical diagnosis and understanding of DILI disease mechanisms may be improved by further investigation of novel biomarkers, and this IL-4 signal in serum is important as proof of concept for prospective study designs.

Prophylactic consequences of sodium salicylate nanoparticles in cisplatin-mediated hepatotoxicity

Unintended side effects linked to the antineoplastic drug cisplatin are a major drawback in its clinical application. The underlying source of these side effects include the generation of reactive oxygen species which are toxic and damaging to tissues and organs. In the present study the anti-inflammatory and antioxidant potential of sodium salicylate was assessed against cisplatin-induced hepatotoxicity in albino rats. Sodium salicylate was used as a model drug and loading into hollow structured porous silica using ultrasound-assisted sol-gel method to produce a nanoemulsion. Transmission Electron Microscopy and Dynamic Light scattering analysis were employed to assess the structural properties and stability of this model. Liver function was assessed by measuring biomarkers including ALT, AST & GGT and oxidant/antioxidant markers including MDA, NO, PON, GSH, MCP1 & AVP in serum or liver tissue. Additionally, blood leukocyte DNA damage was evaluated. Cisplatin significantly altered the normal levels of all biomarkers confirming its hepatotoxic effects. In contrast, treatment with sodium salicylate-loaded silica nanoemulsion significantly restored the levels of these markers. The finding suggests the protective effects of this model drug in preventing cisplatin-induced hepatotoxicity, and therefore may have implications in attenuating cisplatin-induced hepatotoxicity.

Dietary cholesterol in alcohol-associated liver disease

There is an increasing prevalence of alcohol-associated liver disease (ALD) worldwide. In addition to excessive alcohol consumption, other nutritional factors have been shown to affect the initiation and progression of ALD. The emerging role of cholesterol in exacerbating ALD has been reported recently and the underlying mechanisms are discussed. In addition, the interplay between dietary cholesterol and alcohol on cholesterol metabolism is reviewed. Furthermore, we highlight the therapeutic potential of cholesterol-lowering drugs in managing the onset and severity of ALD. Finally, we suggest the future mechanistic investigation of the effect of cholesterol on insulin resistance and intestinal inflammation in the exacerbation of alcohol-induced cellular and systemic dysfunction.

Synbiotic Intervention Ameliorates Oxidative Stress and Gut Permeability in an In Vitro and In Vivo Model of Ethanol-Induced Intestinal Dysbiosis

Alcoholic liver disease (ALD) alters gut microbiota and tight junctions, causing bacterial components to enter the portal vein and induce oxidative stress-induced inflammation in the liver. Only corticosteroids and liver transplants are treatment options for severe alcoholic hepatitis. ALD's pathophysiology is unknown. However, acetaldehyde's toxic effects cause oxidative stress and intestinal permeability. This study investigates the influence of a synbiotic (a combination of aged garlic extract (AGE) and Lactobacillus rhamnosus MTCC1423) on colonic oxidative stress and inflammation in ALD male Wistar rats and Caco2 cells. MDA measurement by HPLC in CaCo2 cells, blood serum, and colon tissue demonstrated that synbiotic treatment in the ALD model reduces oxidative stress. Further, fecal high-throughput 16S rRNA gene sequencing revealed the microbiome's shift towards Firmicutes in the synbiotic group compared to ethanol. In addition, DCFDA labeling and H/E staining demonstrate that the synbiotic is beneficial in inhibiting the development of ALD. In the colon, the synbiotic reduces the activation of CYP2E1 and the inflammatory markers TNF-a and IL-6 while elevating the mRNA expression of ZO-1, occludin, and IL-10. Synbiotics colonize Lactobacillus to restore barrier function and microbiota and reduce colon oxidative stress. Thus, a synbiotic combination can be used in ALD treatment.

Hepatic CYP2B10 is highly induced by binge ethanol and contributes to acute-on-chronic alcohol-induced liver injury

BACKGROUND

The chronic-plus-binge model of ethanol consumption, where chronically (8-week) ethanol-fed mice are gavaged a single dose of ethanol (E8G1), is known to induce steatohepatitis in mice. However, how chronically ethanol-fed mice respond to multiple binges of ethanol remains unknown.

METHODS

We extended the E8G1 model to three gavages of ethanol (E8G3) spaced 24 h apart, sacrificed each group 9 h after the final gavage, analyzed liver injury, and examined gene expression changes using microarray analyses in each group to identify mechanisms contributing to liver responses to binge ethanol.

RESULTS

Surprisingly, E8G3 treatment induced lower levels of liver injury, steatosis, inflammation, and fibrosis as compared to mice after E8G1 treatment. Microarray analyses identified several pathways that may contribute to the reduced liver injury after E8G3 treatment compared to E8G1 treatment. The gene encoding cytochrome P450 2B10 (Cyp2b10) was one of the top upregulated genes in the E8G1 group and was further upregulated in the E8G3 group, but only moderately induced after chronic ethanol consumption, as confirmed by RT-qPCR and western blot analyses. Genetic disruption of Cyp2b10 worsened liver injury in E8G1 and E8G3 mice with higher blood ethanol levels compared to wild-type control mice, while in vitro experiments revealed that CYP2b10 did not directly promote ethanol metabolism. Metabolomic analyses revealed significant differences in hepatic metabolites from E8G1-treated Cyp2b10 knockout and WT mice, and these metabolic alterations may contribute to the reduced liver injury in Cyp2b10 knockout mice.

CONCLUSION

Hepatic Cyp2b10 expression is highly induced after ethanol binge, and such upregulation reduces acute-on-chronic ethanol-induced liver injury via the indirect modification of ethanol metabolism.

Suppression of colonic oxidative stress caused by chronic ethanol administration and attenuation of ethanol-induced colitis and gut leakiness by oral administration of sesaminol in mice

Chronic consumption of excess ethanol is one of the major risk factors for colorectal cancer (CRC), and the pathogenesis of ethanol-related CRC (ER-CRC) involves ethanol-induced oxidative-stress and inflammation in the colon and rectum, as well as gut leakiness. In this study, we hypothesised that oral administration of sesaminol, a sesame lignan, lowers the risk of ER-CRC because we found that it is a strong antioxidant with very low prooxidant activity. This hypothesis was examined using a mouse model, in which 2.0% v/v ethanol was administered ad libitum for 2 weeks with or without oral gavage with sesaminol (2.5 mg per day). Oral sesaminol administration suppressed the ethanol-induced colonic lesions and the ethanol-induced elevation of the colonic levels of oxidative stress markers (8-hydroxy-2'-deoxyguanosine, malondialdehyde, and 4-hydroxyalkenals). It consistently suppressed the chronic ethanol-induced expressions of cytochrome P450-2E1 and inducible nitric oxide synthase and upregulated heme oxygenase-1 expression, probably via the nuclear factor erythroid-derived 2-like 2 pathway in the mouse colon. Oral sesaminol administration also suppressed the chronic ethanol-induced elevation of colonic inflammation marker levels, such as those of tumour necrosis factor-α, interleukin-6, and monocyte chemoattractant protein-1, probably via the nuclear factor-kappa B pathway. Moreover, it prevented the chronic ethanol-induced gut leakiness by restoring tight junction proteins, giving rise to lower plasma endotoxin levels compared with those of ethanol-administered mice. All of these results suggest that dietary supplementation of sesaminol may lower the risk of ER-CRC by suppressing each of the above-mentioned steps in ER-CRC pathogenesis.

Protective effect of curcumin on zebrafish liver under ethanol-induced oxidative stress

Oxidative stress has an important role in determining severe damage to the liver, including steatosis. Curcumin (CUR) is a natural polyphenol compound with antioxidant potential but its mechanism is still unclear. In this study, 2% ethanol (ETH) was used to establish a liver injury model in Tg (fabp10: Ps Red) transgenic zebrafish with the fluorescent liver. Ethanol-treated zebrafish had an increased vacuole rate at 144 h post-fertilization (hpf), thus confirming the effectiveness of the proposed model in inducing liver damage. However, when ethanol was submitted to co-exposure with curcumin, fluorescence area and signal intensity, as well as vacuole rate, were similar to the levels found in the control group. RNA-seq results showed that ethanol and CUR affected the regulation of catalytic activity and phenylalanine metabolism, biosynthesis of amino acids, and arginine and proline metabolism signaling pathways. QRT-PCR analysis also showed that treatment with CUR led to the downregulation of genes involved in the Nrf2-Keap1 signaling pathway and altered the expression pattern of genes related to glutathione metabolism (gsr, gpx1a, gstp1, gsto1, and idh1a). CUR also induced an increase in GSH content and recovered decreased GSH caused by ethanol exposure. The findings discussed herein indicate that CUR can promote glutathione synthesis, which aided in the recovery from ethanol-induced liver damage in zebrafish larvae.

Moringa oleifera mitigates ethanol-induced oxidative stress, fatty degeneration and hepatic steatosis by promoting Nrf2 in mice

BACKGROUND

Moringa oleifera (M. oleifera) is cultivated throughout the world and it is known by numerous regional names and is consumed as medication for various diseases such as hypertension, diabetes, HIV and is potential source of nutrients and natural antioxidants making it among the most useful trees.

METHODS

We evaluated the therapeutic potential of M. oleifera on ethanol-induced fatty liver. The mice were treated with 30% ethanol (EtOH) alone or in combination with different concentration of M. oleifera extracts (100, 200 and 400 mg/kg). We performed biochemical estimation for the serum of important liver damage markers such as aspartate aminotransferase (AST), alanine aminotransferase (ALT) and triglyceride (TG). We performed histopathological analysis from the liver tissues of different mice groups. We also performed ELISA assay, western blotting analysis and SPECT imaging to obtain our results.

RESULTS

The results for serum (AST, p < 0.0001), (ALT, p < 0.0006) and triglyceride (TG, p < 0.0003) were found to be significantly reduced in all doses of M. oleifera extract treatment groups in comparison with the ethanol group. H&E staining analysis and scoring revealed a significant reduction in lipid droplet accumulation and a significant reduction of liver steatosis (p < 0.0001), lobular inflammation (p < 0.0013), ballooning (p < 0.0004) and immunohistochemistry for TNF-α. M. oleifera also ameliorated ethanol-induced oxidative stress evaluated through MDA (p < 0.0001), H₂DCFDA, JC-1 staining and a significant down-regulation of CYP2E1 enzyme (p < 0.0001) in the 200 and 400 mg/kg groups in comparison with EtOH groups. M. oleifera extract also boosted the antioxidant response evaluated through total GSH assay (p < 0.0001) and nuclear translocation of Nrf2. Furthermore, we performed SPECT imaging and evaluated the liver uptake value (LUV) to assess the extent of liver damage. LUV was observed to be lower in the ethanol group, whereas LUV was higher in control and M. olifera treated groups.

CONCLUSION

In summary, from this experiment we conclude that M. oleifera extract has the potential to ameliorate ethanol-induced liver damage.

Cytochrome P450 2E1-dependent hepatic ethanol metabolism induces fatty acid-binding protein 4 and steatosis

BACKGROUND

Hepatic steatosis is an early pathology of alcohol-associated liver disease (ALD). Fatty acid-binding protein-4 (FABP4, a FABP not normally produced in the liver) is secreted by hepatocytes in ALD and stimulates hepatoma proliferation and migration. This study sought to investigate the mechanism[s] by which hepatic ethanol metabolism regulates FABP4 and steatosis.

METHODS

Human hepatoma cells (HepG2/HuH7) and cells stably transfected to express cytochrome P450 2E1 (CYP2E1), were exposed to ethanol in the absence or presence of chlormethiazole (a CYP2E1-inhibitor; CMZ) and/or EX-527 (a sirtuin-1 [SIRT1] inhibitor). The culture medium was analyzed for ethanol metabolism and FABP4 protein abundance. Cells were analyzed for FABP4 mRNA expression, SIRT1 protein abundance, and neutral lipid accumulation. In parallel, cells were analyzed for forkhead box O1 [FOXO1], β-catenin, peroxisome proliferator-activated receptor-α [PPARα], and lipin-1α protein abundance in the absence or presence of ethanol and pharmacological inhibitors of the respective target proteins.

RESULTS

CYP2E1-dependent ethanol metabolism inhibited the amount of SIRT1 protein detected, concomitant with increased FABP4 mRNA expression, FABP4 protein secretion, and neutral lipid accumulation, effects abolished by CMZ. Analysis of pathways associated with lipid oxidation revealed increased FOXO1 nuclear localization and decreased β-catenin, PPARα, and lipin-1α protein levels in CYP2E1-expressing cells in the presence of ethanol. Pharmacological inhibition of SIRT1 mimicked the effects of ethanol, while inhibition of FOXO1 abrogated the effect of ethanol on FABP4 mRNA expression, FABP4 protein secretion, and neutral lipid accumulation in CYP2E1-expressing cells. Pharmacological inhibition of β-catenin, PPARα, or lipin-1α failed to alter the effects of ethanol on FABP4 or neutral lipid accumulation.

CONCLUSION

CYP2E1-dependent ethanol metabolism inhibits SIRT1-FOXO1 signaling, which leads to increased FABP4 mRNA expression, FABP4 protein secretion, and neutral lipid accumulation. These data suggest that FABP4 released from steatotic hepatocytes could play a role in promoting tumor cell expansion in the setting of ALD and represents a potential target for therapeutic intervention.

Aldehyde Trapping by ADX-102 Is Protective against Cigarette Smoke and Alcohol Mediated Lung Cell Injury

Most individuals diagnosed with alcohol use disorders smoke cigarettes. Large concentrations of malondialdehyde and acetaldehyde are found in lungs co-exposed to cigarette smoke and alcohol. Aldehydes directly injure lungs and form aldehyde protein adducts, impacting epithelial functions. Recently, 2-(3-Amino-6-chloroquinolin-2-yl)propan-2-ol (ADX-102) was developed as an aldehyde-trapping drug. We hypothesized that aldehyde-trapping compounds are protective against lung injury derived from cigarette smoke and alcohol co-exposure. To test this hypothesis, we pretreated mouse ciliated tracheal epithelial cells with 0-100 µM of ADX-102 followed by co-exposure to 5% cigarette smoke extract and 50 mM of ethanol. Pretreatment with ADX-102 dose-dependently protected against smoke and alcohol induced cilia-slowing, decreases in bronchial epithelial cell wound repair, decreases in epithelial monolayer resistance, and the formation of MAA adducts. ADX-102 concentrations up to 100 µM showed no cellular toxicity. As protein kinase C (PKC) activation is a known mechanism for slowing cilia and wound repair, we examined the effects of ADX-102 on smoke and alcohol induced PKC epsilon activity. ADX-102 prevented early (3 h) activation and late (24 h) autodownregulation of PKC epsilon in response to smoke and alcohol. These data suggest that reactive aldehydes generated from cigarette smoke and alcohol metabolism may be potential targets for therapeutic intervention to reduce lung injury.

Exposure to binge ethanol and fatty acid ethyl esters exacerbates chronic ethanol-induced pancreatic injury in hepatic alcohol dehydrogenase-deficient deer mice

Alcoholic chronic pancreatitis (ACP) is a fibroinflammatory disease of the pancreas. However, metabolic basis of ACP is not clearly understood. In this study, we evaluated differential pancreatic injury in hepatic alcohol dehydrogenase-deficient (ADH^-) deer mice fed chronic ethanol (EtOH), chronic plus binge EtOH, and chronic plus binge EtOH and fatty acid ethyl esters (FAEEs, nonoxidative metabolites of EtOH) to understand the metabolic basis of ACP. Hepatic ADH^- and ADH normal (ADH⁺) deer mice were fed Lieber-DeCarli liquid diet containing 3% (wt/vol) EtOH for 3 mo. One week before the euthanization, chronic EtOH-fed mice were further administered with an oral gavage of binge EtOH with/without FAEEs. Blood alcohol concentration (BAC), pancreatic injury, and inflammatory markers were measured. Pancreatic morphology, ultrastructural changes, and endoplasmic reticulum (ER)/oxidative stress were examined using H&E staining, electron microscopy, immunostaining, and/or Western blot, respectively. Overall, BAC was substantially increased in chronic EtOH-fed groups of ADH^- versus ADH⁺ deer mice. A significant change in pancreatic acinar cell morphology, with mild to moderate fibrosis and ultrastructural changes evident by dilatations and disruption of ER cisternae, ER/oxidative stress along with increased levels of inflammatory markers were observed in the pancreas of chronic EtOH-fed groups of ADH^- versus ADH⁺ deer mice. Furthermore, chronic plus binge EtOH and FAEEs exposure elevated BAC, enhanced ER/oxidative stress, and exacerbated chronic EtOH-induced pancreatic injury in ADH^- deer mice suggesting a role of increased body burden of EtOH and its metabolism under reduced hepatic ADH in initiation and progression of ACP.NEW & NOTEWORTHY We established a chronic EtOH feeding model of hepatic alcohol dehydrogenase-deficient (ADH^-) deer mice, which mimics several fibroinflammatory features of human alcoholic chronic pancreatitis (ACP). The fibroinflammatory and morphological features exacerbated by chronic plus binge EtOH and FAEEs exposure provide a strong case for metabolic basis of ACP. Most importantly, several pathological and molecular targets identified in this study provide a much broader understanding of the mechanism and avenues to develop therapeutics for ACP.

A retinoic acid receptor β2 agonist protects against alcohol liver disease and modulates hepatic expression of canonical retinoid metabolism genes

Alcohol abuse reduces hepatic vitamin A (retinoids), reductions that are associated with progression of alcohol liver disease (ALD). Restoring hepatic retinoids through diet is contraindicated in ALD due to the negative effects of alcohol on retinoid metabolism. There are currently no drugs that can both mitigate alcohol-driven hepatic retinoid losses and progression of ALD. Using a mouse model of alcohol intake, we examined if an agonist for the retinoic acid (RA) receptor β2 (RARβ2), AC261066 (AC261) could prevent alcohol-driven hepatic retinoid losses and protect against ALD. Our results show that mice co-treated with AC261 and alcohol displayed mitigation of ALD, including reduced macro, and microvesicular steatosis, and liver damage. Alcohol intake led to increases in hepatic centrilobular levels of ALDH1A1, a rate-limiting enzyme in RA synthesis, and co-localization of ALDH1A1 with the alcohol-metabolizing enzyme CYP2E1, and 4-HNE, a marker of oxidative stress; expression of these targets was abrogated in mice co-treated with AC261 and alcohol. By RNA sequencing technology, we found that AC261 treatments opposed alcohol modulation of 68 transcripts involved in canonical retinoid metabolism. Alcohol modulation of these transcripts, including CES1D, CES1G, RBP1, RDH10, and CYP26A1, collectively favor hepatic retinoid hydrolysis and catabolism. However, despite this, co-administration of AC261 with alcohol did not mitigate alcohol-mediated depletions of hepatic retinoids, but did reduce alcohol-driven increases in serum retinol. Our data show that AC261 protected mice against ALD, even though AC261 did not prevent alcohol-mediated reductions in hepatic retinoids. These data warrant further studies of the anti-ALD properties of AC261.

Withaferin A alleviates ethanol-induced liver injury by inhibiting hepatic lipogenesis

Withaferin A (WA) is a natural steroidal compound with reported hepatoprotective activities against various liver diseases. Whether WA has therapeutic effects on alcoholic liver disease has not been explored. A binge alcoholic liver injury model was employed by feeding C57BL/6J mice an ethanol (EtOH) diet for 10 days followed by an acute dose of EtOH to mimic clinical acute-upon-chronic liver injury. In this binge model, WA significantly reduced the binge EtOH-induced increase of serum aminotransaminase levels and decreased hepatic lipid accumulation. Mechanistically, WA decreased levels of hepatic lipogenesis gene mRNAs in vivo, including Srebp1c, Fasn, Acc1 and Fabp1. In EtOH-treated primary hepatocytes in vitro, WA decreased lipid accumulation by lowering the expression of the lipogenesis gene mRNAs Fasn and Acc1 as well as decreasing hepatocyte death. In the established binge alcoholic liver injury model, WA therapeutically reduced the EtOH-induced increase of serum aminotransaminase levels as well as hepatic lipid accumulation. These results demonstrate that WA reduces EtOH-induced liver injury by inhibiting hepatic lipogenesis, suggesting a potential therapeutic option for treating alcoholic liver injury.

Targeting Peroxisome Proliferator-Activated Receptor-β/δ (PPARβ/δ) for the Treatment or Prevention of Alcoholic Liver Disease

Excessive, chronic alcohol consumption can lead to alcoholic liver disease. The etiology of alcoholic liver disease is multifactorial and is influenced by alterations in gene expression and changes in fatty acid metabolism, oxidative stress, and insulin resistance. These events can lead to steatosis, fibrosis, and eventually to cirrhosis and liver cancer. Many of these functions are regulated by peroxisome proliferator-activated receptors (PPARs). Thus, it is not surprising that PPARs can modulate the mechanisms that cause alcoholic liver disease. While the roles of PPARα and PPARγ are clearer, the role of PPARβ/δ in alcoholic liver disease requires further clarification. This review summarizes the current understanding based on recent studies that indicate that PPARβ/δ can likely be targeted for the treatment and/or the prevention of alcoholic liver disease.

Prophylactic Treatment of Probiotic and Metformin Mitigates Ethanol-Induced Intestinal Barrier Injury: In Vitro, In Vivo, and In Silico Approaches

Ethanol depletes intestinal integrity and promotes gut dysbiosis. Studies have suggested the individual role of probiotics and metformin Met in protecting intestinal barrier function from injuries induced by ethanol. The objective of the current study is to investigate the potential mechanism by which coadministration of probiotic Visbiome® (V) and Met blocks the ethanol-induced intestinal barrier dysfunction/gut leakiness utilizing Caco-2 monolayers, a rat model with chronic ethanol injury, and in silico docking interaction models. In Caco-2 monolayers, exposure to ethanol significantly disrupted tight junction (TJ) localization, elevated monolayer permeability, and oxidative stress compared with controls. However, cotreatment with probiotic V and Met largely ameliorated the ethanol-induced mucosal barrier dysfunction, TJ disruption, and gut oxidative stress compared with ethanol-exposed monolayers and individual treatment of either agent. Rats fed with ethanol-containing Lieber-DeCarli liquid diet showed decreased expression of TJ proteins, and increased intestinal barrier injury resulting in pro-inflammatory response and oxidative stress in the colon. We found that co-administration of probiotic V and Met improved the expression of intestinal TJ proteins (ZO-1 and occludin) and upregulated the anti-inflammatory response, leading to reduced ER stress. Moreover, co-administration of probiotic V and Met inhibited the CYP2E1 and NOX gene expression, and increase the translocation of Nrf-2 as well as anti-oxidative genes (SOD, catalase, Gpx, and HO-1), leading to reduced colonic ROS content and malondialdehyde levels. The combined treatment of probiotic V and Met also improved their binding affinities towards HO-1, Nrf-2, SLC5A8, and GPR109A, which could be attributed to their synergistic effect. Our findings based on in-vitro, in-vivo, and in-silico analyses suggest that the combination of probiotic V and Met potentially acts in synergism, attributable to their property of inhibition of inflammation and oxidative stress against ethanol-induced intestinal barrier injury.

Effects of Roasted Schisandra Chinensis (Turcz.) Baill and Lycium Chinense Mill. and Their Combinational Extracts on Antioxidant and Anti-Inflammatory Activities in RAW 264.7 Cells and in Alcohol-Induced Liver Damage Mice Model

Schisandra chinensis (Turcz.) Baill (SC) and Lycium chinense Mill. (LC) are widely distributed in Asia, where the fruit has traditionally been used for medicinal herbs. We previously reported that the roasting process improved the antioxidant and their hangover relieving effects. In this study, we assessed the antioxidant and anti-inflammatory effects of water extract of SC, LC, and a mass ratio 1 : 1 mixture (SL), after roasting in RAW264.7 macrophage cells stimulated with lipopolysaccharide (LPS). Roasted SL (RSL) extracts showed greater enhancement potential than the others, based on the inhibition of NO (nitric oxide) and intracellular reactive oxygen species (ROS) production in RAW264.7 cells. RSL also significantly decreased the proinflammatory markers (e.g., iNOS, COX-2, TNF-α, and IL-1β) and NAD(P)H oxidase (NOX) signaling proteins (i.e., NOX (-1, -2, and -4), p22^phox, p47^phox, and p67^phox). The inflammatory cytokine, tumor necrosis factor-alpha, interferon-1 beta levels, NF-kB, and mitogen-activated kinase activations were also significantly inhibited by RSL treatment. Based on the results of cellular levels, we compared the promotion effects of RSL extract on liver injury mediated by alcohol-induced inflammation and oxidative stress in mice. Mice were fed a Lieber-DeCarli regular liquid alcohol diet with or without SL and RSL extracts for six weeks. Alcohol intake caused liver injury, evidenced by an increase in serum alanine aminotransferase and aspartate aminotransferase activities. Consistent with the results in cell levels, RSL treatment remarkably downregulated ROS and inflammatory factors, as well as their signaling molecules, in serum and tissues. These results suggest that the roasting of SC and LC could potentially elevate the inhibition effect on alcohol-induced inflammation and oxidative stress and consequently prevent alcoholic liver damage. Also, the combination of SC and LC may provide a more synergistic effect than either alone.

Ellagic Acid Prevents Binge Alcohol-Induced Leaky Gut and Liver Injury through Inhibiting Gut Dysbiosis and Oxidative Stress

Alcoholic liver disease (ALD) is a major liver disease worldwide and can range from simple steatosis or inflammation to fibrosis/cirrhosis, possibly through leaky gut and systemic endotoxemia. Many patients with alcoholic steatohepatitis (ASH) die within 60 days after clinical diagnosis due to the lack of an approved drug, and thus, synthetic and/or dietary agents to prevent ASH and premature deaths are urgently needed. We recently reported that a pharmacologically high dose of pomegranate extract prevented binge alcohol-induced gut leakiness and hepatic inflammation by suppressing oxidative and nitrative stress. Herein, we investigate whether a dietary antioxidant ellagic acid (EA) contained in many fruits, including pomegranate and vegetables, can protect against binge alcohol-induced leaky gut, endotoxemia, and liver inflammation. Pretreatment with a physiologically-relevant dose of EA for 14 days significantly reduced the binge alcohol-induced gut barrier dysfunction, endotoxemia, and inflammatory liver injury in mice by inhibiting gut dysbiosis and the elevated oxidative stress and apoptosis marker proteins. Pretreatment with EA significantly prevented the decreased amounts of gut tight junction/adherent junction proteins and the elevated gut leakiness in alcohol-exposed mice. Taken together, our results suggest that EA could be used as a dietary supplement for alcoholic hepatitis patients.

A mini-review of the rodent models for alcoholic liver disease: shortcomings, application, and future prospects

Rodents are the most common models in studies of alcoholic liver disease (ALD). Although several rodents ALD models have been established and multiple mechanisms have been elucidated based on them, these models have some non-negligible shortcomings, specifically only inducing early stage (mainly steatosis, slight to moderate steatohepatitis) but not the whole spectrum of human ALD. The resistance of rodents to advanced ALD has been suggested to be due to the physiological differences between rodents and human beings. Previous studies have reported significant interstrain differences in the susceptibility to ethanol-induced liver injury and in the manifestation of ALD (such as different alteration of lipid profiles). Therefore, it would be interesting to characterize the manifestation of ethanol-induced liver damage in various rodents, which may provide a recommendation to investigators of ALD. Furthermore, more severe ALD models need to be established for the study of serious ALD forms, which may be achieved by using genetic modified rodents.

Effects of long-term ethanol ingestion on hepatic iron metabolism in two mouse strains

The mechanisms responsible for dysregulation of iron metabolism in response to ethanol ingestion are poorly understood. Relatively brief ethanol exposures in rodents are associated with reduced hepatic hepcidin expression without increases in hepatic iron content. This study evaluated the effects of long-term ethanol treatment on hepatic iron metabolism in two mouse strains. Ethanol was administered in the drinking water to C57BL/6 and BALB/c mice for up to 11 months. Hepatic histology and iron concentrations (HIC) were assessed, along with expression of relevant genes and proteins by real-time RT-PCR and western blot, respectively. The livers of ethanol-consuming mice of both strains showed mild steatosis without inflammation or fibrosis. Stainable hepatocyte iron was modestly increased in both strains ingesting ethanol, although hepatic iron concentrations were significantly higher only in C57BL/6 mice. Long-term ethanol did not affect hepcidin mRNA (Hamp1 or Hamp2) in either strain, nor was the expression of several oxidative stress-responsive genes (glutamate cysteine ligase, gamma-glutamyl transpeptidase, heme oxygenase-1 and growth differentiation factor 15) altered in response to ethanol, suggesting that oxidative stress and suppression of hepcidin expression in short-term ethanol feeding models may be transient phenomena that resolve as mice adapt to ethanol exposure. This murine model of chronic ethanol ingestion demonstrates modest increases in hepatic iron without changes in hepcidin expression, markers of oxidative stress or significant histologic liver injury. Further investigations are needed to characterize the mechanisms of dysregulated iron metabolism resulting from chronic ethanol ingestion.

Association between chronic psychoactive substances use and systemic inflammation: A systematic review and meta-analysis

This systematic review and meta-analysis assess the change in inflammation biomarkers level among chronic psychoactive substance users. To meet the required inclusion criteria, all studies had to describe human participants with an age ≥18y., experiencing chronic psychostimulant (nicotine, amphetamine, cocaine), sedative (benzodiazepine, opioids) and/or cannabinoid use. The comparison group was defined as healthy participants. Studies where included if they reported at least one of the pro/inflammatory biomarkers. Study bias was examined by Funnel plots and heterogeneity by computing the I² statistics. Only 21 eligible studies were selected based on 26,216 study participants. A small and significant effect size of 0.18 mg/l (95 % CI:0.10-0.27) was detected in favour of chronic smokers (z = 4.33;P < 0.0001). There was evidence of publication bias for studies measuring IL-6 and IL-10 association with cocaine and IL-6 in association with cannabis. In summary, except for chronic tobacco users, there was no evidence of association between other chronic substances abuse and inflammatory levels. More studies are needed to inform policy and decision makers about the utility of anti-inflammatory based targeted intervention programmes.

Sulforaphane ameliorates ethanol plus carbon tetrachloride-induced liver fibrosis in mice through the Nrf2-mediated antioxidant response and acetaldehyde metabolization with inhibition of the LPS/TLR4 signaling pathway

Alcoholic liver disease (ALD)-related fibrosis results from a variety of mechanisms including the accumulation of acetaldehyde, reactive oxygen species, and hepatic overload of endogenous lipopolysaccharide (LPS). Alcohol cessation is the therapeutic mainstay for patients with all stages of ALD, whereas pharmacological strategies for liver fibrosis have not been established. Sulforaphane, a phytochemical found in cruciferous vegetables, activates nuclear factor erythroid 2-related factor 2 (Nrf2) and exerts anticancer, antidiabetic, and antimicrobial effects; however, few studies investigated its efficacy in the development of ALD-related fibrosis. Herein, we investigated the effect of sulforaphane on acetaldehyde metabolism and liver fibrosis in HepaRG and LX-2 cells, human hepatoma and hepatic stellate cell lines, respectively, as well as in a mouse model of alcoholic liver fibrosis induced by ethanol plus carbon tetrachloride (EtOH/CCl₄). Sulforaphane treatment induced the activity of acetaldehyde-metabolizing mitochondrial aldehyde dehydrogenase in HepaRG cells and suppressed the acetaldehyde-induced proliferation and profibrogenic activity in LX-2 cells with upregulation of Nrf2-regulated antioxidant genes, including HMOX1, NQO1, and GSTM3. Moreover, sulforaphane attenuated the LPS/toll-like receptor 4-mediated sensitization to transforming growth factor-β with downregulation of NADPH oxidase 1 (NOX1) and NOX4. In EtOH/CCl₄-treated mice, oral sulforaphane administration augmented hepatic acetaldehyde metabolism. Additionally, sulforaphane significantly inhibited Kupffer cell infiltration and fibrosis, decreased fat accumulation and lipid peroxidation, and induced Nrf2-regulated antioxidant response genes in EtOH/CCl₄-treated mice. Furthermore, sulforaphane treatment blunted hepatic exposure of gut-derived LPS and suppressed hepatic toll-like receptor 4 signaling pathway. Taken together, these results suggest sulforaphane as a novel therapeutic strategy in ALD-related liver fibrosis.

In vitro inhibitory effects of ganoderic acid A on human liver cytochrome P450 enzymes

Context: Ganoderic acid A (GAA) is usually used to prevent cancers or other diseases, which make it likely to be used with other drugs metabolized by cytochromes P450.Objective: This study investigates the effect of GAA on eight major cytochrome P450 isoforms in human liver microsomes.Material and method: The effects of GAA (100 μM) on eight human liver CYP isoforms (i.e., 1A2, 3A4, 2A6, 2E1, 2D6, 2C9, 2C19, and 2C8) were investigated in vitro using human liver microsomes (HLMs) with specific substrates for the CYPs, and the enzyme kinetic parameters were calculated.Results: The results showed that GAA inhibited the activity of CYP3A4, 2D6, and 2E1, but did not affect other isoforms. The inhibition of CYP3A4, 2D6, and 2E1 was concentration-dependent with IC₅₀ values of 15.05, 21.83, and 28.35 μM, respectively. Additionally, GAA was not only a non-competitive inhibitor of CYP3A4, but also a competitive inhibitor of CYP2D6 and 2E1, with Ki values of 7.16, 10.07, and 13.45 μM. Meanwhile, the inhibition of CYP3A4 was time-dependent, with the K_I/K_inact value of 7.91/0.048 μM/min.Discussion and conclusion: The in vitro study indicated that GAA has the potential to result in drug-drug interactions with other drugs metabolized by CYP3A4, 2D6, and 2E1. Further clinical studies are needed for the identification of this interaction.

MEHP/ethanol co-exposure favors the death of steatotic hepatocytes, possibly through CYP4A and ADH involvement

Liver steatosis has been associated with various etiological factors (obesity, alcohol, environmental contaminants). How those factors work together to induce steatosis progression is still scarcely evaluated. Here, we tested whether phthalates could potentiate death of steatotic hepatocytes when combined with ethanol. Pre-steatotic WIF-B9 hepatocytes were co-exposed to mono (2-ethylhexyl) (MEHP, 500 nM; main metabolite of di (2-ethylhexyl) phthalate or DEHP) and ethanol (5 mM) for 5 days. An increased apoptotic death was detected, involving a DNA damage response. Using 4-Methypyrazole to inhibit ethanol metabolism, and CH-223191 to antagonize the AhR receptor, we found that an AhR-dependent increase in alcohol dehydrogenase (ADH) activity was essential for cell death upon MEHP/ethanol co-exposure. Toxicity was also prevented by HET0016 to inhibit the cytochrome P450 4A (CYP4A). Using the antioxidant thiourea, a role for oxidative stress was uncovered, notably triggering DNA damage. Finally, co-exposing the in vivo steatosis model of high fat diet (HFD)-zebrafish larvae to DEHP (2.56 nM)/ethanol (43 mM), induced the pathological progression of liver steatosis alongside an increased Cyp4t8 (human CYP4A homolog) mRNA expression. Altogether, these results further emphasized the deleterious impact of co-exposures to ethanol/environmental pollutant towards steatosis pathological progression, and unraveled a key role for ADH and CYP4A in such effects.

Roles of peroxisome proliferator-activated receptor α in the pathogenesis of ethanol-induced liver disease

Alcoholic liver disease (ALD) is a progressively aggravated liver disease with high incidence in alcoholics. Ethanol-induced fat accumulation and the subsequent lipopolysaccharide (LPS)-driven inflammation bring liver from reversible steatosis, to irreversible hepatitis, fibrosis, cirrhosis, and even hepatocellular carcinoma. Peroxisome proliferator-activated receptor α (PPARα) is a member of the nuclear receptor superfamily of ligand-activated transcription factors and plays pivotal roles in the regulation of fatty acid homeostasis as well as the inflammation control in the liver. It has been well documented that PPARα activity and/or expression are downregulated in liver of mice exposed to ethanol, which is thought to be one of the prime contributors to ethanol-induced steatosis, hepatitis and fibrosis. This article summarizes the current evidences from in vitro and animal models for the critical roles of PPARα in the onset and progression of ALD. Importantly, it should be noted that the expression of PPARα in human liver is reported to be similar to that in mice, and PPARα expression is downregulated in the liver of patients with nonalcoholic fatty liver disease (NAFLD), a disease sharing many similarities with ALD. Therefore, clinical trials investigating the expression of PPARα in the liver of ALD patients and the efficacy of strong PPARα agonists for the prevention and treatment of ALD are warranted.

Linking Dysregulated AMPK Signaling and ER Stress in Ethanol-Induced Liver Injury in Hepatic Alcohol Dehydrogenase Deficient Deer Mice

Ethanol (EtOH) metabolism itself can be a predisposing factor for initiation of alcoholic liver disease (ALD). Therefore, a dose dependent study to evaluate liver injury was conducted in hepatic alcohol dehydrogenase (ADH) deficient (ADH⁻) and ADH normal (ADH⁺) deer mice fed 1%, 2% or 3.5% EtOH in the liquid diet daily for 2 months. Blood alcohol concentration (BAC), liver injury marker (alanine amino transferase (ALT)), hepatic lipids and cytochrome P450 2E1 (CYP2E1) activity were measured. Liver histology, endoplasmic reticulum (ER) stress, AMP-activated protein kinase (AMPK) signaling and cell death proteins were evaluated. Significantly increased BAC, plasma ALT, hepatic lipids and steatosis were found only in ADH⁻ deer mice fed 3.5% EtOH. Further, a significant ER stress and increased un-spliced X-box binding protein 1 were evident only in ADH⁻ deer mice fed 3.5% EtOH. Both strains fed 3.5% EtOH showed deactivation of AMPK, but increased acetyl Co-A carboxylase 1 and decreased carnitine palmitoyltransferase 1A favoring lipogenesis were found only in ADH⁻ deer mice fed 3.5% EtOH. Therefore, irrespective of CYP2E1 overexpression; EtOH dose and hepatic ADH deficiency contribute to EtOH-induced steatosis and liver injury, suggesting a linkage between ER stress, dysregulated hepatic lipid metabolism and AMPK signaling.

Xian-Ling-Gu-Bao induced inflammatory stress rat liver injury: Inflammatory and oxidative stress playing important roles

ETHNOPHARMACOLOGICAL RELEVANCE

Xian-Ling-Gu-Bao (XLGB) Fufang is an herbal formula that has been used in clinical settings to treat osteoporosis, osteoarthritis, aseptic bone necrosis, and climacteric syndrome. Despite its uses, XLGB treatment has been linked to potential liver injury. To date, there is a lack of clear demonstration of such toxicity in animal models.

AIM OF THE STUDY

As animal models fail to reproduce the XLGB hepatotoxicity reported in humans, because human hepatocytes are clearly more sensitive to XLGB, this study was designed to investigate a more reliable animal model of such toxicity.

MATERIALS AND METHODS

We randomized rats into five groups, as follows: CON (control), XLGB, lipopolysaccharide (LPS), L-XLGB/LPS (XLGB, 0.125 g/kg; LPS, 0.1 mg/kg), and XLGB/LPS (XLGB, 1.25 g/kg; LPS, 0.1 mg/kg). These groups were treated with 0.5% sodium carboxymethyl cellulose (CMC-Na), XLGB suspension, normal saline, or LPS. The first administration of XLGB [0.125 g/kg or 1.25 g/kg, by mouth (PO)] or its solvent (0.5% CMC-Na) was delivered, and then food was removed. Twelve hours after the first administration of XLGB, rats received LPS [0.1 mg/kg, intravenously (IV)] or saline control. After 30 min, a second administration of XLGB (0.125 g/kg or 1.25 g/kg, PO) or solvent was administered. The rats were anesthetized at 12 h or 24 h following the second administration of XLGB. Liver function was evaluated by measuring liver weight, liver microscopy, serum biochemistry and plasma microRNA-122 (miR-122). The plasma levels of 27 cytokines were measured to evaluate inflammation. Moreover, the expression of cytochrome P450 2E1 (CYP2E1), nicotinic adenine dinucleotide phosphate (NADPH) oxidase and inducible nitric oxide synthase (iNOS) at protein levels were observed; immunofluorescence and immunohistochemistry were used to confirmed the hepatotoxicity of XLGB.

RESULTS

Hepatotoxicity in male rats with moderate inflammation induced by XLGB was indicated by liver histopathology, serum biochemical analysis, serum miR-122 levels, and immunofluorescent assessments. We observed significant increases in liver weight and liver indexes in male rats with moderate inflammation in response to XLGB. Histopathological assessment further showed that extensive hepatocellular necrosis and inflammatory infiltration were evident in rats co-treated with XLGB/LPS. The levels of serum transaminases [alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT)], total bilirubin (TBIL) and triglyceride (TG), which are markers of liver function, were also significantly increased by XLGB/LPS treatment. Similarly, miR-122 was significantly elevated in XLGB/LPS treated rats relative to other groups. An immunofluorescent assessment showed extensive apoptosis in hepatocytes from these co-treated rats. What is more, XLGB can dose-dependently induce liver injury in male rats with moderate inflammation. Hepatic CYP2E1, neutrophil chemotactic factor (NCF-1), iNOS, and NOX-2 (an NADPH oxidase subunit) levels were increased in response to XLGB treatment, and staining for DMPO nitrone adducts further showed elevated oxidative stress level in XLGB/LPS-treated rats relative to the other experimental groups.

CONCLUSION

LPS and XLGB co-treatment in rats led to marked hepatotoxicity. This toxicity was associated with disrupted lipid metabolism, extensive liver necrosis and inflammatory infiltration, apoptosis, and expression of oxidative stress-related proteins. These results demonstrate a valuable model for the study of iDILI in the context of XLGB treatment, and further provide insights into the potential mechanisms by which XLGB may induce hepatotoxicity in humans.

Ethanol Exposure Impairs AMPK Signaling and Phagocytosis in Human Alveolar Macrophages: Role of Ethanol Metabolism

BACKGROUND

Chronic alcohol consumption impairs alveolar macrophage's (AM) function and increases risk for developing lung infection and pneumonia. However, the mechanism and metabolic basis of alcohol-induced AM dysfunction leading to lung infection are not well defined, but may include altered ethanol (EtOH) and reactive oxygen species metabolism and cellular energetics. Therefore, oxidative stress, endoplasmic reticulum (ER) stress, the formation of fatty acid ethyl esters [FAEEs, nonoxidative metabolites of EtOH], AMP-activated protein kinase (AMPK) signaling, and phagocytic function were examined in freshly isolated AM incubated with EtOH.

METHODS

AMs separated from bronchoalveolar lavage fluid samples obtained from normal volunteers were incubated with EtOH for 24 hours. AMPK signaling and ER stress were assessed using Western blotting, FAEEs by GC-MS, oxidative stress by immunofluorescence using antibodies to 4-hydroxynonenal, and phagocytosis by latex beads. Oxidative stress was also measured in EtOH-treated AMs with/without AMPK activator [5-aminoimidazole-4-carboxamide ribonucleotide (AICAR)] or inhibitor (Compound C), and in AMs incubated with FAEEs. mRNA expression for interleukins (IL-6 and IL-8), monocyte chemoattractant protein (MCP)-1, and transforming growth factor (TGF)-β was measured in AM treated with EtOH or FAEEs using RT-PCR.

RESULTS

EtOH exposure to AM increased oxidative stress, ER stress, and synthesis of FAEEs, decreased phosphorylated AMPK, and impaired phagocytosis. Attenuation or exacerbation of EtOH-induced oxidative stress by AICAR or Compound C, respectively, suggests a link between AMPK signaling, EtOH metabolism, and related oxidative stress. The formation of FAEEs may contribute to EtOH-induced oxidative stress as FAEEs also produced concentration-dependent oxidative stress. An increased mRNA expression of IL-6, IL-8, and MCP-1 by FAEEs is key finding to suggest a metabolic basis of EtOH-induced inflammatory response.

CONCLUSIONS

EtOH-induced impaired phagocytosis, oxidative stress, ER stress, and dysregulated AMPK signaling are plausibly associated with the formation of FAEEs and may participate in the pathogenesis of nonspecific pulmonary inflammation.

Chronic intake of high-dose of blueberry leaf extract does not augment the harmful effects of ethanol in rats

Excessive alcohol consumption is a risk factor for liver diseases. Enhancement of alcohol metabolism could be an effective strategy to prevent these adverse effects since it promotes the clearance of ethanol and acetaldehyde from the serum. Polyphenol-rich products have shown to protect against alcohol-related liver damage. Blueberry leaves have attracted attention as they are rich polyphenols such as proantocyanidins and chlorogenic acid. In this study, we investigated the effects of a high dose of blueberry leaf extract (BLEx) on alcohol metabolism during chronic intake of ethanol. Seven-week old Sprague-Dawley (SD) rats were divided into four groups: normal liquid diet group (NLD), normal liquid diet + BLEx group (NLD + BLEx), alcohol liquid diet group (ALD), and alcohol liquid diet + BLEx (ALD + BLEx). Then, rats were fed experimental diet for 5 weeks and at the end of feeding period, body weight, food intake, liver weight, indices of liver injury, expression and activity of alcohol metabolism-related and anti-oxidative enzymes, and levels of carbonyl protein, triglyceride (TG), and total cholesterol (T-Chol) were measured. Body weight and food intake decreased, whereas liver aldehyde dehydrogenase (ALDH) activity, liver microsomal cytochrome P450 2E1 (CYP2E1) protein and mRNA expression, and heme oxygenase 1 (HO-1) mRNA expression were upregulated by ethanol intake. Dietary BLEx, however, did not affect any of these ethanol-related changes. Indices of liver injury, expression and activity of other alcohol metabolism-related enzymes, liver carbonyl protein, TG, and T-Chol levels were not altered by ethanol and BLEx. Thus, chronic BLEx intake does not ameliorate the harmful effects of ethanol.

The effects of non-esterified fatty acids and β-hydroxybutyrate on the hepatic CYP2E1 in cows with clinical ketosis

Dairy cows with ketosis display severe oxidative stress as well as high blood concentrations of non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHB). Cytochrome P4502E1 (CYP2E1) plays an important role in the induction of oxidative stress. The aim of this study was to investigate CYP2E1 expression and activity in the liver of clinically ketotic cows (in vivo) and the effects of NEFA and BHB on CYP2E1 expression and activity in hepatocytes (in vitro). Dairy cows with clinical ketosis exhibited a low blood concentration of glucose but high concentrations of NEFA and BHB. Hepatic mRNA, protein expression, and activity of CYP2E1 were significantly higher in cows with clinical ketosis than in control cows. In vitro, both NEFA and BHB treatment markedly up-regulated the mRNA and protein expressions as well as activity of CYP2E1 in cow hepatocytes. Taken together, these results indicate that high levels of NEFA and BHB significantly up-regulate the expression and activity of hepatic CYP2E1, and may be influential in the induction of oxidative stress in cows with clinical ketosis.

Toxic effects of combined treatment of 1,2-dichloroethane and ethanol on mouse brain and the related mechanisms

The aim of this study was to explore the mechanisms of brain damage induced by the combined treatment of mice with 1,2-dichloroethane (1,2-DCE) and ethanol. Mice were divided into control group; 1,2-DCE-intoxicated group; ethanol-treated group; and low-, medium-, and high-dose combined treatment groups. Histological observations along with brain organ coefficients and water content were used to measure the brain damage directly and indirectly. The levels of nonprotein sulfhydryls, malondialdehyde (MDA), and superoxide dismutase activity were used as parameters to evaluate oxidative stress in the brain. Protein and messenger RNA (mRNA) levels of cytochrome P450 2E1 (CYP2E1), zonula occludens-1 (occludin and zo-1), aquaporin-4 (AQP4), nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase (HO)-1, and the γ-glutamyl cysteine synthetase catalytic and modulatory subunits (γ-GCSc, GR, and γ-GCSm) in the brain were examined by Western blot analysis and quantitative polymerase chain reaction analysis, respectively. Effects of the combined treatment of 1,2-DCE and ethanol were evaluated by analysis of variance with a factorial design. The results suggested that combined exposure to ethanol and 1,2-DCE synergistically increased CYP2E1 protein and mRNA levels, accelerated the metabolism of ethanol and 1,2-DCE in the brain tissue, induced high production of reactive oxygen species (ROS), and increased MDA levels, thereby damaging the blood-brain barrier and causing obvious pathological changes in brain tissue. However, the increased level of ROS activated the Nrf2 signal transduction pathway, promoting the expression of HO-1 and glutathione-related antioxidant enzymes in the brain to protect the cells from oxidative damage.

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.

Mechanistic insights of hepatoprotective effects of curcumin: Therapeutic updates and future prospects

The liver is the most essential organ of the body performing vital functions. Hepatic disorders affect the physiological and biochemical functions of the body. These disorders include hepatitis B, hepatitis C, alcoholic liver disease (ALD), nonalcoholic fatty liver disease (NAFLD), liver cirrhosis, hepatic failure and hepatocellular carcinoma (HCC). Drugs related hepatotoxicity is one of the major challenges facing by clinicians as it is a leading cause of liver failure. During post-marketing surveillance studies, detection and reporting of drug-induced hepatotoxicity may lead to drug withdrawal or warnings. Several mechanisms are involved in hepatotoxicity such as cell membrane disruption, initiating an immune response, alteration of cellular pathways of drug metabolism, accumulation of reactive oxygen species (ROS), lipid peroxidation and cell death. Curcumin, the active ingredient of turmeric and exhibits therapeutic potential for the treatment of diabetes, cardiovascular disorders and various types of cancers. Curcumin is strong anti-oxidant and anti-inflammatory effects and thus it possesses hepatoprotective properties. Despite its low bioavailability, its hepatoprotective effects have been studied in various protocols of hepatotoxicity including acetaminophen, alcohol, lindane, carbon tetrachloride (CCL₄), diethylnitrosamine and heavy metals induced hepatotoxicities. This report reviews the hepatoprotective effects of curcumin with a focus on its mechanistic insights in various hepatotoxic protocols.

Alcoholic Liver Disease: Alcohol Metabolism, Cascade of Molecular Mechanisms, Cellular Targets, and Clinical Aspects

Alcoholic liver disease is the result of cascade events, which clinically first lead to alcoholic fatty liver, and then mostly via alcoholic steatohepatitis or alcoholic hepatitis potentially to cirrhosis and hepatocellular carcinoma. Pathogenetic events are linked to the metabolism of ethanol and acetaldehyde as its first oxidation product generated via hepatic alcohol dehydrogenase (ADH) and the microsomal ethanol-oxidizing system (MEOS), which depends on cytochrome P450 2E1 (CYP 2E1), and is inducible by chronic alcohol use. MEOS induction accelerates the metabolism of ethanol to acetaldehyde that facilitates organ injury including the liver, and it produces via CYP 2E1 many reactive oxygen species (ROS) such as ethoxy radical, hydroxyethyl radical, acetyl radical, singlet radical, superoxide radical, hydrogen peroxide, hydroxyl radical, alkoxyl radical, and peroxyl radical. These attack hepatocytes, Kupffer cells, stellate cells, and liver sinusoidal endothelial cells, and their signaling mediators such as interleukins, interferons, and growth factors, help to initiate liver injury including fibrosis and cirrhosis in susceptible individuals with specific risk factors. Through CYP 2E1-dependent ROS, more evidence is emerging that alcohol generates lipid peroxides and modifies the intestinal microbiome, thereby stimulating actions of endotoxins produced by intestinal bacteria; lipid peroxides and endotoxins are potential causes that are involved in alcoholic liver injury. Alcohol modifies SIRT1 (Sirtuin-1; derived from Silent mating type Information Regulation) and SIRT2, and most importantly, the innate and adapted immune systems, which may explain the individual differences of injury susceptibility. Metabolic pathways are also influenced by circadian rhythms, specific conditions known from living organisms including plants. Open for discussion is a 5-hit working hypothesis, attempting to define key elements involved in injury progression. In essence, although abundant biochemical mechanisms are proposed for the initiation and perpetuation of liver injury, patients with an alcohol problem benefit from permanent alcohol abstinence alone.

Metabolic pharmacokinetics of early chronic alcohol consumption mediated by liver alcohol dehydrogenases 1 and 3 in mice

BACKGROUND AND AIM

Alcohol dehydrogenases (ADHs) 1 and 3 are responsible for systemic alcohol metabolism. The current study investigated the contribution of liver ADH1 and ADH3 to the metabolic pharmacokinetics of chronic alcohol consumption (CAC).

METHODS

The 9-week-old male mice of different ADH genotypes (wild-type [WT], Adh1^-/- , and Adh3^-/- ) were administered with 10% ethanol solution for 1 month, followed by acute ethanol administration (4.0 g/kg). The alcohol elimination rate (AER), area under the blood alcohol concentration curve (AUC), and the maximum blood alcohol concentration (C_max ) were calculated. The liver content, activity, and mRNA levels of ADH were evaluated.

RESULTS

Chronic alcohol consumption increased the AER and reduced the AUC in all ADH genotypes. The increased ADH1 content was correlated with AER in WT mice but not in the Adh3^-/- mice. Similarly, the increased ADH3 content was also correlated with AER in both WT and Adh1^-/- mice. The C_max was significantly higher in Adh3^-/- control mice than in WT control mice. It decreased in the Adh1^-/- mice by CAC along with an increase in the ADH3 content.

CONCLUSIONS

Alcohol dehydrogenases 1 and 3 would accomplish the pharmacokinetic adaptation to CAC in the early period. ADH1 contributes to the metabolic pharmacokinetics of CAC with a decrease in AUC in conjunction with an increase of AER by increasing the enzyme content in the presence of ADH3. ADH3 also contributes to a decrease in AUC in conjunction with not only an increase in AER but also a decrease in C_max by increasing the enzyme content.

The relationships between cytochromes P450 and H2O2: Production, reaction, and inhibition

In this review we address the relationship between cytochromes P450 (P450) and H2O2. This association can affect biology in three distinct ways. First, P450s produce H2O2 as a byproduct either during catalysis or when no substrate is present. This reaction, known as uncoupling, releases reactive oxygen species that may have implications in disease. Second, H2O2 is used as an oxygen-donating co-substrate in peroxygenase and peroxidase reactions catalyzed by P450s. This activity has proven to be important mainly in reactions involving prokaryotic P450s, and investigators have harnessed this reaction with the aim of adaptation for industrial use. Third, H2O2-dependent inhibition of human P450s has been studied in our laboratory, demonstrating heme destruction and also the inactivating oxidation of the heme-thiolate ligand to a sulfenic acid (-SOH). This reversible oxidative modification of P450s may have implications in the prevention of uncoupling and may give new insights into the oxidative regulation of these enzymes. Research has elucidated many of the chemical mechanisms involved in the relationship between P450 and H2O2, but the application to biology is difficult to evaluate. Further studies are needed reveal both the harmful and protective natures of reactive oxygen species in an organismal context.

Pomegranate prevents binge alcohol-induced gut leakiness and hepatic inflammation by suppressing oxidative and nitrative stress

Alcoholic liver disease (ALD) is a major chronic liver disease worldwide and can range from simple steatosis, inflammation to fibrosis/cirrhosis possibly through leaky gut and systemic endotoxemia. We investigated whether pomegranate (POM) protects against binge alcohol-induced gut leakiness, endotoxemia, and inflammatory liver damage. After POM pretreatment for 10 days, rats were exposed to 3 oral doses of binge alcohol (5 g/kg/dose) or dextrose (as control) at 12-h intervals. Binge alcohol exposure induced leaky gut with significantly elevated plasma endotoxin and inflammatory fatty liver by increasing the levels of oxidative and nitrative stress marker proteins such as ethanol-inducible CYP2E1, inducible nitric oxide synthase, and nitrated proteins in the small intestine and liver. POM pretreatment significantly reduced the alcohol-induced gut barrier dysfunction, plasma endotoxin and inflammatory liver disease by inhibiting the elevated oxidative and nitrative stress marker proteins. POM pretreatment significantly restored the levels of intestinal tight junction (TJ) proteins such as ZO-1, occludin, claudin-1, and claundin-3 markedly diminished after alcohol-exposure. In addition, the levels of gut adherent junction (AJ) proteins (e.g., β-catenin and E-cadherin) and desmosome plakoglobin along with associated protein α-tubulin were clearly decreased in binge alcohol-exposed rats but restored to basal levels in POM-pretreated rats. Immunoprecipitation followed by immunoblot analyses revealed that intestinal claudin-1 protein was nitrated and ubiquitinated in alcohol-exposed rats, whereas these modifications were significantly blocked by POM pretreatment. These results showed for the first time that POM can prevent alcohol-induced gut leakiness and inflammatory liver injury by suppressing oxidative and nitrative stress.

P450-Humanized and Human Liver Chimeric Mouse Models for Studying Xenobiotic Metabolism and Toxicity

Preclinical evaluation of drug candidates in experimental animal models is an essential step in drug development. Humanized mouse models have emerged as a promising alternative to traditional animal models. The purpose of this mini-review is to provide a brief survey of currently available mouse models for studying human xenobiotic metabolism. Here, we describe both genetic humanization and human liver chimeric mouse models, focusing on the advantages and limitations while outlining their key features and applications. Although this field of biomedical science is relatively young, these humanized mouse models have the potential to transform preclinical drug testing and eventually lead to a more cost-effective and rapid development of new therapies.

Capsaicin, the pungent principle of peppers, ameliorates alcohol-induced acute liver injury in mice via modulation of matrix metalloproteinases

Alcohol, the most common cause for hepatic injury, may further deteriorate the hepatic tissue when left unattended. Capsaicin, the pungent principle of chilli peppers, possesses antioxidant and anti-inflammatory properties and is a proven dietary antioxidant in various ailments. However, its role in alcohol-induced hepatic injury is unclear. In this study, we investigated the effects of capsaicin on the hepatic tissue of mice treated with alcohol. Acute liver injury was induced in mice by oral gavage of 5 doses of 10 mL/kg of 50% ethyl alcohol at an interval of 12 h. The tissue antioxidant levels along with the mitochondrial functional parameters and matrix metalloproteinase levels were evaluated in the hepatic tissues of mice following alcohol challenge. The results showed that alcohol intake significantly attenuated the hepatic antioxidant levels and mitochondrial function. These changes were accompanied by enhanced serum hepatic injury markers and matrix metalloproteinases. However, capsaicin treatment (10 and 20 mg/kg, oral) throughout the experimental period caused a drastic improvement in the hepatic tissue of the alcohol-treated mice, reflected by the normalization of hepatic enzyme and protein levels along with restored histological alterations. These results indicate that capsaicin, as a dietary intervention, may prevent alcohol-induced acute liver injury.

Inorganic arsenic causes fatty liver and interacts with ethanol to cause alcoholic liver disease in zebrafish

The rapid increase in fatty liver disease (FLD) incidence is attributed largely to genetic and lifestyle factors; however, environmental toxicants are a frequently overlooked factor that can modify the effects of more common causes of FLD. Chronic exposure to inorganic arsenic (iAs) is associated with liver disease in humans and animal models, but neither the mechanism of action nor the combinatorial interaction with other disease-causing factors has been fully investigated. Here, we examined the contribution of iAs to FLD using zebrafish and tested the interaction with ethanol to cause alcoholic liver disease (ALD). We report that zebrafish exposed to iAs throughout development developed specific phenotypes beginning at 4 days post-fertilization (dpf), including the development of FLD in over 50% of larvae by 5 dpf. Comparative transcriptomic analysis of livers from larvae exposed to either iAs or ethanol revealed the oxidative stress response and the unfolded protein response (UPR) caused by endoplasmic reticulum (ER) stress as common pathways in both these models of FLD, suggesting that they target similar cellular processes. This was confirmed by our finding that arsenic is synthetically lethal with both ethanol and a well-characterized ER-stress-inducing agent (tunicamycin), suggesting that these exposures work together through UPR activation to cause iAs toxicity. Most significantly, combined exposure to sub-toxic concentrations of iAs and ethanol potentiated the expression of UPR-associated genes, cooperated to induce FLD, reduced the expression of as3mt, which encodes an arsenic-metabolizing enzyme, and significantly increased the concentration of iAs in the liver. This demonstrates that iAs exposure is sufficient to cause FLD and that low doses of iAs can potentiate the effects of ethanol to cause liver disease.

This article has an associated First Person interview with the first author of the paper.

Summary: Using zebrafish, the authors show that exposure to a common environmental contaminant, inorganic arsenic, increases the risk of alcoholic liver disease.

Hepatic alcohol dehydrogenase deficiency induces pancreatic injury in chronic ethanol feeding model of deer mice

The single most common cause of chronic pancreatitis (CP, a serious inflammatory disease) is chronic alcohol abuse, which impairs hepatic alcohol dehydrogenase (ADH, a major ethanol oxidizing enzyme). Previously, we found ~5 fold greater fatty acid ethyl esters (FAEEs), and injury in the pancreas of hepatic ADH deficient (ADH^-) vs. hepatic normal ADH (ADH⁺) deer mice fed 3.5g% ethanol via liquid diet daily for two months. Therefore, progression of ethanol-induced pancreatic injury was determined in ADH^- deer mice fed ethanol for four months to delineate the mechanism and metabolic basis of alcoholic chronic pancreatitis (ACP). In addition to a substantially increased blood alcohol concentration and plasma FAEEs, significant degenerative changes, including atrophy and loss of acinar cells in some areas, ultrastructural changes evident by such features as swelling and disintegration of endoplasmic reticulum (ER) cisternae and ER stress were observed in the pancreas of ethanol-fed ADH^- deer mice vs. ADH⁺ deer mice. These changes are consistent with noted increases in pancreatic injury markers (plasma lipase, pancreatic trypsinogen activation peptide, FAEE synthase and cathepsin B) in ethanol-fed ADH^- deer mice. Most importantly, an increased levels of pancreatic glucose regulated protein (GRP) 78 (a prominent ER stress marker) were found to be closely associated with increased phosphorylated eukaryotic initiation factor (eIF) 2α signaling molecule in PKR-like ER kinase branch of unfolded protein response (UPR) as compared to X box binding protein 1S and activating transcription factor (ATF)6 - 50kDa protein of inositol requiring enzyme 1α and ATF6 branches of UPR, respectively, in ethanol-fed ADH^- vs. ADH⁺ deer mice. These results along with findings on plasma FAEEs, and pancreatic histology and injury markers suggest a metabolic basis of ethanol-induced pancreatic injury, and provide new avenues to understand metabolic basis and molecular mechanism of ACP.