Safety, Pharmacokinetics, and Efficacy Signals of Larsucosterol (DUR-928) in Alcohol-Associated Hepatitis.

INTRODUCTION: This study is to evaluate the safety and pharmacokinetics (PK) of larsucosterol (DUR-928 or 25HC3S) in subjects with alcohol-associated hepatitis (AH), a devastating acute illness without US Food and Drug Administration-approved therapies. METHODS: This phase 2a, multicenter, open-label, dose escalation study evaluated the safety, PK, and efficacy signals of larsucosterol in 19 clinically diagnosed subjects with AH. Based on the model for end-stage liver disease (MELD) score, 7 subjects were considered to have moderate AH and 12 to have severe AH. All subjects received 1 or 2 intravenous infusions (72 hours apart) of larsucosterol at a dose of 30, 90, or 150 mg and were followed up for 28 days. Efficacy signals from a subgroup of subjects with severe AH were compared with those from 2 matched arms of those with severe AH treated with standard of care (SOC), including corticosteroids, from a contemporaneous study. RESULTS: All 19 larsucosterol-treated subjects survived the 28-day study. Fourteen (74%) of all subjects including 8 (67%) of the subjects with severe AH were discharged ≤72 hours after receiving a single infusion. There were no drug-related serious adverse events nor early terminations due to the treatment. PK profiles were not affected by disease severity. Biochemical parameters improved in most subjects. Serum bilirubin levels declined notably from baseline to day 7 and day 28, and MELD scores were reduced at day 28. The efficacy signals compared favorably with those from 2 matched groups treated with SOC. Lille scores at day 7 were <0.45 in 16 of the 18 (89%) subjects with day 7 samples. Lille scores from 8 subjects with severe AH who received 30 or 90 mg larsucosterol (doses used in phase 2b trial) were statistically significantly lower ( P < 0.01) than those from subjects with severe AH treated with SOC from the contemporaneous study. DISCUSSION: Larsucosterol was well tolerated at all 3 doses in subjects with AH without safety concerns. Data from this pilot study showed promising efficacy signals in subjects with AH. Larsucosterol is being evaluated in a phase 2b multicenter, randomized, double-blinded, placebo-controlled (AHFIRM) trial.

Western diet unmasks transient low-level vinyl chloride-induced tumorigenesis; potential role of the (epi-)transcriptome.

BACKGROUND & AIMS: Vinyl chloride (VC) monomer is a volatile organic compound commonly used in industry. At high exposure levels, VC causes liver cancer and toxicant-associated steatohepatitis. However, lower exposure levels (i.e., sub-regulatory exposure limits) that do not directly damage the liver, enhance injury caused by Western diet (WD). It is still unknown if the long-term impact of transient low-concentration VC enhances the risk of liver cancer development. This is especially a concern given that fatty liver disease is in and of itself a risk factor for the development of liver cancer. METHODS: C57Bl/6 J mice were fed WD or control diet (CD) for 1 year. During the first 12 weeks of feeding only, mice were also exposed to VC via inhalation at sub-regulatory limit concentrations (<1 ppm) or air for 6 h/day, 5 days/week. RESULTS: Feeding WD for 1 year caused significant hepatic injury, which was exacerbated by VC. Additionally, VC increased the number of tumors which ranged from moderately to poorly differentiated hepatocellular carcinoma (HCC). Transcriptomic analysis demonstrated VC-induced changes in metabolic but also ribosomal processes. Epitranscriptomic analysis showed a VC-induced shift of the modification pattern that has been associated with metabolic disease, mitochondrial dysfunction, and cancer. CONCLUSIONS: These data indicate that VC sensitizes the liver to other stressors (e.g., WD), resulting in enhanced tumorigenesis. These data raise concerns about potential interactions between VC exposure and WD. It also emphasizes that current safety restrictions may be insufficient to account for other factors that can influence hepatotoxicity.

Polychlorinated biphenyls alter hepatic m6A mRNA methylation in a mouse model of environmental liver disease.

Exposure to polychlorinated biphenyls (PCBs) has been associated with liver injury in human cohorts and with nonalcoholic steatohepatitis (NASH) in mice fed a high fat diet (HFD). N (6)-methyladenosine (m6A) modification of mRNA regulates transcript fate, but the contribution of m6A modification on the regulation of transcripts in PCB-induced steatosis and fibrosis is unknown. This study tested the hypothesis that PCB and HFD exposure alters the levels of m6A modification in transcripts that play a role in NASH in vivo. Male C57Bl6/J mice were fed a HFD (12 wks) and administered a single oral dose of Aroclor1260, PCB126, or Aroclor1260 + PCB126. Genome-wide identification of m6A peaks was accomplished by m6A mRNA immunoprecipitation sequencing (m6A-RIP) and the mRNA transcriptome identified by RNA-seq. Exposure of HFD-fed mice to Aroclor1260 decreased the number of m6A peaks and m6A-containing genes relative to PCB vehicle control whereas PCB126 or the combination of Aroclor1260 + PCB126 increased m6A modification frequency. ∼41% of genes had one m6A peak and ∼49% had 2-4 m6A peaks. 117 m6A peaks were common in the four experimental groups. The Aroclor1260 + PCB126 exposure group showed the highest number (52) of m6A-peaks. qRT-PCR confirmed enrichment of m6A-containing fragments of the Apob transcript with PCB exposure. A1cf transcript abundance, m6A peak count, and protein abundance was increased with Aroclor1260 + PCB126 co-exposure. Irrespective of the PCB type, all PCB groups exhibited enriched pathways related to lipid/lipoprotein metabolism and inflammation through the m6A modification. Integrated analysis of m6A-RIP-seq and mRNA-seq identified 242 differentially expressed genes (DEGs) with increased or reduced number of m6A peaks. These data show that PCB exposure in HFD-fed mice alters the m6A landscape offering an additional layer of regulation of gene expression affecting a subset of gene responses in NASH.

Can Zinc Supplementation Attenuate High Fat Diet-Induced Non-Alcoholic Fatty Liver Disease?

The pathogenesis of non-alcoholic fatty liver disease (NAFLD), the most prevalent chronic liver disease, is associated with zinc deficiency. Previous studies show zinc supplementation improves steatosis and glucose metabolism, but its therapeutic effects in patients with established NAFLD remain unclear. We developed an in vivo model to characterize the effects of zinc supplementation on high-fat diet (HFD) induced NAFLD and hypothesized that the established NAFLD would be attenuated by zinc supplementation. Male C57BL/6J mice were fed a control diet or HFD for 12 weeks. Mice were then further grouped into normal and zinc-supplemented diets for 8 additional weeks. Body composition and glucose tolerance were determined before and after zinc supplementation. At euthanasia, plasma and liver tissue were collected for characterization and downstream analysis. As expected, 12 weeks of HFD resulted in reduced glucose clearance and altered body composition. Eight weeks of subsequent zinc supplementation did not alter glucose handling, plasma transaminases, steatosis, or hepatic gene expression. Results from our model suggest 8-week zinc supplementation cannot reverse established NAFLD. The HFD may have caused NAFLD disease progression beyond rescue by an 8-week period of zinc supplementation. Future studies will address these limitations and provide insights into zinc as a therapeutic agent for established NAFLD.

Whole life exposure to low dose cadmium alters diet-induced NAFLD.

Nonalcoholic fatty liver disease (NAFLD) is a major global public health concern affecting more than 25% of the world's population. Although obesity and diabetes are major risk factors for NAFLD, they cannot account for all cases, indicating the importance of other factors such as environmental exposures. Cadmium (Cd) exposure is implicated in the development of NAFLD; however, the influence of early life, in utero Cd exposure on the development of diet-induced NAFLD is poorly understood. Therefore, we developed an in vivo, multiple-hit model to study the effect of whole-life, low dose Cd exposure on high fat diet (HFD)-induced NAFLD. Adult male and female C57BL/6 J mice fed normal diets (ND) were exposed to 0, 0.5 or 5 ppm Cd-containing drinking water for 14 weeks before breeding. At weaning, offspring were fed ND or HFD and continued on the same drinking water regimen as their parents for 24 weeks. Cd exposure at different concentrations differentially altered HFD-associated adverse health effects, including liver injury. HFD-induced increased body weight, decreased glucose tolerance. Liver injury and lipid deposition were exacerbated by 5 ppm Cd exposure but attenuated by 0.5 ppm Cd exposure. Further, HFD blunted the response of metallothionein, a major Cd detoxification protein, in mice exposed to 5 ppm Cd but enhanced the response in mice exposed to 0.5 ppm Cd, suggesting a possible mechanism for Cd alteration of HFD-induced NAFLD. These results confirm the multi-hit nature of NAFLD and show whole life, low dose Cd exposure alters HFD-induced NAFLD with outcomes dependent on Cd concentration.

Effect of vinyl chloride exposure on cardiometabolic toxicity.

Vinyl chloride (VC) is an organochlorine mainly used to manufacture its polymer polyvinyl chloride, which is extensively used in the manufacturing of consumer products. Recent studies suggest that chronic low dose VC exposure affects glucose homeostasis in high fat diet-fed mice. Our data suggest that even in the absence of high fat diet, exposure to VC (0.8 ppm, 6 h/day, 5 day/week, for 12 weeks) induces glucose intolerance (1.0 g/kg, i.p.) in male C57BL/6 mice. This was accompanied with the depletion of hepatic glutathione and a modest increase in lung interstitial macrophages. VC exposure did not affect the levels of circulating immune cells, endothelial progenitor cells, platelet-immune cell aggregates, and cytokines and chemokines. The acute challenge of VC-exposed mice with LPS did not affect lung immune cell composition or plasma IL-6. To examine the effect of VC exposure on vascular inflammation and atherosclerosis, LDL receptor-KO mice on C57BL/6 background maintained on western diet were exposed to VC for 12 weeks (0.8 ppm, 6 h/day, 5 day/week). Unlike the WT C57BL/6 mice, VC exposure did not affect glucose tolerance in the LDL receptor-KO mice. Plasma cytokines, lesion area in the aortic valve, and markers of lesional inflammation in VC-exposed LDL receptor-KO mice were comparable with the air-exposed controls. Collectively, despite impaired glucose tolerance and modest pulmonary inflammation, chronic low dose VC exposure does not affect surrogate markers of cardiovascular injury, LPS-induced acute inflammation in C57BL/6 mice, and chronic inflammation and atherosclerosis in the LDL receptor-KO mice.

Plasma Metabolomics Analysis of Polyvinyl Chloride Workers Identifies Altered Processes and Candidate Biomarkers for Hepatic Hemangiosarcoma and Its Development.

BACKGROUND: High-level occupational vinyl chloride (VC) exposures have been associated with hepatic hemangiosarcoma, which typically develops following a long latency period. Although VC is genotoxic, a more comprehensive mode of action has not been determined and diagnostic biomarkers have not been established. The purpose of this study is to address these knowledge gaps through plasma metabolomics. METHODS: Plasma samples from polyvinyl chloride polymerization workers who developed hemangiosarcoma (cases, n = 15) and VC exposure-matched controls (n = 17) underwent metabolomic analysis. Random forest and bioinformatic analyses were performed. RESULTS: Cases and controls had similar demographics and routine liver biochemistries. Mass spectroscopy identified 606 known metabolites. Random forest analysis had an 82% predictive accuracy for group classification. 60 metabolites were significantly increased and 44 were decreased vs. controls. Taurocholate, bradykinin and fibrin degradation product 2 were up-regulated by greater than 80-fold. The naturally occurring anti-angiogenic phenol, 4-hydroxybenzyl alcohol, was down-regulated 5-fold. Top affected ontologies involved: (i) metabolism of bile acids, taurine, cholesterol, fatty acids and amino acids; (ii) inflammation and oxidative stress; and (iii) nicotinic cholinergic signaling. CONCLUSIONS: The plasma metabolome was differentially regulated in polyvinyl chloride workers who developed hepatic hemangiosarcoma. Ontologies potentially involved in hemangiosarcoma pathogenesis and candidate biomarkers were identified.

Keratin 18 Is a Diagnostic and Prognostic Factor for Acute Alcoholic Hepatitis.

BACKGROUND & AIMS: Acute alcoholic hepatitis (AAH) is a major cause of liver-related morbidity and mortality; there are no good blood biomarkers for diagnosis or determining magnitude of cell death. Keratin 18 (KRT18, also called K18), found in epithelial cells, is released from hepatocytes upon death. We investigated whether level of K18 is a better marker of hepatocyte death than standard biomarkers and might be used to identify patients with AAH at risk for death within 90 days. METHODS: We analyzed data from 173 participants in a large trial performed at 4 medical centers. Participants with AAH were classified as severe (n = 57, model for end-stage liver disease [MELD] scores above 20) or moderate (n = 27, MELD scores from 12 to 19); 38 participants had alcohol use disorder with mild (n = 28) or no liver injury (n = 10); 34 participants had nonalcoholic steatohepatitis; and 17 participants were healthy (controls). We quantified serum levels of K18 using ELISAs and APOPTOSENSE kits. RESULTS: Serum level of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and the ratio of AST:ALT did not correlate with MELD scores. Patients with alcohol use disorder had higher serum levels of ALT than patients with severe AAH. Levels of K18M65 and K18M30 had statistically significant increases as liver disease worsened, as did the degree of necrosis (ratio of K18 M65:M30). The ratio of K18M65:ALT was increased in serum from patients with AAH compared with controls. Serum levels of K18 identified patients who died within 90 days with greater accuracy than commonly used static biomarkers. CONCLUSIONS: There is a stronger association between serum level of keratin 18 and amount of hepatocyte death and liver disease severity than for other biomarkers (AST, ALT, and the AST:ALT ratio). The ratio of K18M65:M30 might be used as marker of mechanism of hepatocyte death, and the ratio of K18M65:ALT might be used to distinguish patients with AAH from patients with nonalcoholic steatohepatitis. Serum levels of K18 might be used to identify patients with severe AAH at risk for death. ClinicalTrials.gov identifier # NCT01922895 and NCT01809132.

Lower Serum Magnesium Concentrations are associated With Specific Heavy Drinking Markers, Pro-Inflammatory Response and Early-Stage Alcohol-associated Liver Injury§.

AIM: Chronic heavy alcohol intake frequently causes liver inflammation/injury, and altered mineral metabolism may be involved in this liver pathology. In this study, we evaluated the association of heavy drinking, changes in serum magnesium levels and biochemical evidence of liver injury in alcohol-use-disorder (AUD) patients who had no clinical signs or symptoms of liver injury. We also aimed to identify any sex-based differences in patients with mild or no biochemical evidence of liver injury induced by heavy drinking. METHODS: 114 heavy drinking alcohol-dependent (AD) female and male patients aged 21-65 years without clinical manifestations of liver injury, who were admitted to an alcohol treatment program, were grouped by alanine aminotransaminase (ALT) levels: ≤ 40 IU/L, as no liver injury (GR.1), and ALT>40 IU/L as mild liver injury (GR.2). Patients were actively drinking until the day of admission. Comprehensive metabolic biochemistry results, fatty acid panel, serum magnesium and drinking history data were collected at admission; and study-specific measures were evaluated. RESULTS: In all AD patients, lower magnesium was significantly associated with the heavy drinking marker and heavy drinking days past 90 days (HDD90). A lower serum magnesium concentration was observed in AD patients with mild liver injury. Females of both groups had mean levels of magnesium in the deficient range. A clinically significant drop in magnesium levels was observed only in the GR.2 (mild liver injury) male AD patients. Females showed a significant association between low magnesium levels and the ω6:ω3 polyunsaturated fatty acids (PUFAs) ratio. CONCLUSIONS: Specific heavy drinking markers showed an association with lower magnesium levels. Low serum magnesium levels are common in subjects with AUD and appear to be associated with the onset of liver injury.

Dioxin-like and non-dioxin-like PCBs differentially regulate the hepatic proteome and modify diet-induced nonalcoholic fatty liver disease severity.

Polychlorinated biphenyls (PCBs) are persistent organic pollutants associated with metabolic disruption and non-alcoholic fatty liver disease (NAFLD). Based on their ability to activate the aryl hydrocarbon receptor (AhR), PCBs are subdivided into two classes: dioxin-like (DL) and non-dioxin-like (NDL) PCBs. Previously, we demonstrated that NDL PCBs compromised the liver to promote more severe diet-induced NAFLD. Here, the hepatic effects and potential mechanisms (by untargeted liver proteomics) of DL PCBs, NDL PCBs or co-exposure to both in diet-induced NAFLD are investigated. Male C57Bl/6 mice were fed a 42% fat diet and exposed to vehicle control; Aroclor1260 (20 mg/kg, NDL PCB mixture); PCB126 (20 µg/kg, DL PCB congener); or a mixture of Aroclor1260 (20 mg/kg)+PCB126 (20 µg/kg) for 12 weeks. Each exposure was associated with a distinct hepatic proteome. Phenotypic and proteomic analyses revealed increased hepatic inflammation and phosphoprotein signaling disruption by Aroclor1260. PCB126 decreased hepatic inflammation and fibrosis at the molecular level; while altering cytoskeletal remodeling, metal homeostasis, and intermediary/xenobiotic metabolism. PCB126 attenuated Aroclor1260-induced hepatic inflammation but increased hepatic free fatty acids in the co-exposure group. Aroclor1260+PCB126 exposure was strongly associated with multiple epigenetic processes, and these could potentially explain the observed non-additive effects of the exposures on the hepatic proteome. Taken together, the results demonstrated that PCB exposures differentially regulated the hepatic proteome and the histologic severity of diet-induced NAFLD. Future research is warranted to determine the AhR-dependence of the observed effects including metal homeostasis and the epigenetic regulation of gene expression.

Proteomic Analysis Reveals Novel Mechanisms by Which Polychlorinated Biphenyls Compromise the Liver Promoting Diet-Induced Steatohepatitis.

Environmental pollution contributes to fatty liver disease pathogenesis. Polychlorinated biphenyl (PCB) exposures have been associated with liver enzyme elevation and suspected steatohepatitis in cohort studies. Male mice treated with the commercial PCB mixture, Aroclor 1260 (20 mg/kg), and fed high fat diet (HFD) for 12 weeks developed steatohepatitis. Receptor-based modes of action including inhibition of the epidermal growth factor (EGF) receptor were previously proposed, but other mechanisms likely exist. Objectives were to identify and validate the pathways, transcription factors, and mechanisms responsible for the steatohepatitis associated with PCB and HFD coexposures. Comparative proteomics analysis was performed in archived mouse liver samples from the aforementioned chronic exposure study. Pathway and transcription factor analysis (TFA) was performed, and selected results were validated. Liver proteomics detected 1103 unique proteins. Aroclor 1260 upregulated 154 and downregulated 93 of these. Aroclor 1260 + HFD coexposures affected 55 pathways including glutathione metabolism, intermediary metabolism, and cytoskeletal remodeling. TFA of Aroclor 1260 treatment demonstrated alterations in the function of 42 transcription factors including downregulation of NRF2 and key nuclear receptors previously demonstrated to protect against steatohepatitis (e.g., HNF4α, FXR, PPARα/δ/γ, etc.). Validation studies demonstrated that Aroclor 1260 significantly reduced HNF4α protein levels, while Aroclor 1260 + HFD reduced expression of the HNF4α target gene, albumin, in vivo. Aroclor 1260 attenuated EGF-dependent HNF4α phosphorylation and target gene activation in vitro. Aroclor 1260 reduced levels of NRF2, its target genes, and glutathione in vivo. Aroclor 1260 attenuated EGF-dependent NRF2 upregulation, in vitro. Aroclor 1260 indirectly activated hepatic stellate cells in vitro via induction of hepatocyte-derived TGFß. PCB exposures adversely impacted transcription factors regulating liver protection, function, and fibrosis. PCBs, thus, compromised the liver by reducing its protective responses against nutritional stress to promote diet-induced steatohepatitis. The identified mechanisms by which environmental pollutants influence fatty liver disease pathogenesis require confirmation in humans.

Polychlorinated biphenyl exposures differentially regulate hepatic metabolism and pancreatic function: Implications for nonalcoholic steatohepatitis and diabetes.

The endocrine disrupting chemicals, polychlorinated biphenyls (PCBs), have been associated with nonalcoholic steatohepatitis (NASH) and diabetes. However, an integrative analysis of the effects of PCBs on the liver and pancreas has never been performed for the two major PCB subtypes, dioxin-like (DL) and nondioxin-like (NDL), and a mixture of NDL/DL PCBs. Therefore, male C57BL/6 J mice fed a control synthetic diet were treated with either a NDL PCB mixture, Aroclor 1260 (20 mg/kg); a single DL PCB congener, PCB 126 (20 µg/kg); a NDL/DL mixture, Aroclor 1260 plus PCB 126; or vehicle control for 2 weeks. PCB126 had the greatest impact on hepatic lipid metabolism. It caused steatosis due to increased hepatic lipid import with associated hypolipidemia. However, all PCB exposures impacted expression of hepatic lipid metabolism genes in different manners. The 'NASH gene', Pnpla3, was elevated by Aroclor 1260, but decreased by all other exposures. The expression of hepatokines implicated in metabolic syndrome (Fgf21, Igf1, and betatrophin) were differentially regulated. The NDL/DL PCB mixture had the greatest effects on pancreatic histology, including acinar cell atrophy, mild steatosis, and fibrosis without ductal changes or immune cell infiltration. It decreased expression of insulin and altered the expression of genes regulating islet identity. None of these exposures was associated with altered HOMA-IR or HOMA-B. In summary, PCB exposures differentially regulated liver and pancreas structure and function. Novel mechanisms for PCB-induced endocrine/metabolic disruption included altered hepatokines and Pnpla3 as well as 'PCB pancreatopathy' that was associated with altered expression of pancreatic islet identity factors. More research is required to understand fully these findings in the context of human NASH and diabetes.

Concentration dependence of human and mouse aryl hydrocarbon receptor responsiveness to polychlorinated biphenyl exposures: Implications for aroclor mixtures.

1. Aryl hydrocarbon receptor (AhR) ligands, including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and polychlorinated biphenyls (PCBs), are endocrine disrupting chemicals associated with nonalcoholic fatty liver disease. This study documents the species-specific differences between mouse (high affinity mAhR) and human AhR (hAhR) activation by PCB congeners and Aroclor mixtures. 2. AhR activation by TCDD or PCBs 77, 81, 114, 114, 126, and 169 was measured using luciferase reporter constructs transfected into either Hepa1c1c7 mouse or HepG2 human liver cell lines. The EC50 values were lower in Hepa1c1c7 cells than HepG2 cells for all compounds tested except PCB 81. The results for TCDD and PCB 126 were validated in primary human and mouse hepatocytes by measuring CYP1A1 gene transcript levels. 3. Because humans are exposed to PCB mixtures, several mixtures (Aroclors 1254; 1260; and 1260 + 0.1% PCB126 each at 10 µg/ml) were then tested. Neither Aroclor 1254 nor Aroclor 1260 increased luciferase activity by the transfected AhR reporter construct. The Aroclor 1260 + 0.1% PCB 126 mixture induced mAhR-mediated transactivation, but not hAhR activation in cell lines. 4. In summary, significant concentration-dependent differences exist between human and mouse AhR activation by PCBs. Relative effect potencies differed, in some cases, from published toxic equivalency factors.

Dietary copper-fructose interactions alter gut microbial activity in male rats.

Dietary copper-fructose interactions contribute to the development of nonalcoholic fatty liver disease (NAFLD). Gut microbiota play critical roles in the pathogenesis of NAFLD. The aim of this study was to determine the effect of different dietary doses of copper and their interactions with high fructose on gut microbiome. Male weanling Sprague-Dawley rats were fed diets with adequate copper (6 ppm CuA), marginal copper (1.5 ppm CuM) (low copper), or supplemented copper (20 ppm CuS) (high copper) for 4 wk. Deionized water or deionized water containing 30% fructose (wt/vol) was given ad libitum. Copper status, liver enzymes, gut barrier function, and gut microbiome were evaluated. Both low- and high-copper diets led to liver injury in high-fructose-fed rats, and this was associated with gut barrier dysfunction, as shown by the markedly decreased tight junction proteins and increased gut permeability. 16S rDNA sequencing analysis revealed distinct alterations of the gut microbiome associated with dietary low- and high-copper/high-fructose feeding. The common features of the alterations of the gut microbiome were the increased abundance of Firmicutes and the depletion of Akkermansia. However, they differed mainly within the phylum Firmicutes. Our data demonstrated that a complex interplay among host, microbes, and dietary copper-fructose interaction regulates gut microbial metabolic activity, which may contribute to the development of liver injury and hepatic steatosis. The distinct alterations of gut microbial activity, which were associated with the different dietary doses of copper and fructose, imply that separate mechanism(s) may be involved. NEW & NOTEWORTHY First, dietary low- and high-copper/high-fructose-induced liver injury are associated with distinct alterations of gut microbiome. Second, dietary copper level plays a critical role in maintaining the gut barrier integrity, likely by acting on the intestinal tight junction proteins and the protective commensal bacteria Akkermansia. Third, the alterations of gut microbiome induced by dietary low and high copper with or without fructose differ mainly within the phylum Firmicutes.

Nuclear receptors and nonalcoholic fatty liver disease.

Nuclear receptors are transcription factors which sense changing environmental or hormonal signals and effect transcriptional changes to regulate core life functions including growth, development, and reproduction. To support this function, following ligand-activation by xenobiotics, members of subfamily 1 nuclear receptors (NR1s) may heterodimerize with the retinoid X receptor (RXR) to regulate transcription of genes involved in energy and xenobiotic metabolism and inflammation. Several of these receptors including the peroxisome proliferator-activated receptors (PPARs), the pregnane and xenobiotic receptor (PXR), the constitutive androstane receptor (CAR), the liver X receptor (LXR) and the farnesoid X receptor (FXR) are key regulators of the gut:liver:adipose axis and serve to coordinate metabolic responses across organ systems between the fed and fasting states. Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease and may progress to cirrhosis and even hepatocellular carcinoma. NAFLD is associated with inappropriate nuclear receptor function and perturbations along the gut:liver:adipose axis including obesity, increased intestinal permeability with systemic inflammation, abnormal hepatic lipid metabolism, and insulin resistance. Environmental chemicals may compound the problem by directly interacting with nuclear receptors leading to metabolic confusion and the inability to differentiate fed from fasting conditions. This review focuses on the impact of nuclear receptors in the pathogenesis and treatment of NAFLD. Clinical trials including PIVENS and FLINT demonstrate that nuclear receptor targeted therapies may lead to the paradoxical dissociation of steatosis, inflammation, fibrosis, insulin resistance, dyslipidemia and obesity. Novel strategies currently under development (including tissue-specific ligands and dual receptor agonists) may be required to separate the beneficial effects of nuclear receptor activation from unwanted metabolic side effects. The impact of nuclear receptor crosstalk in NAFLD is likely to be profound, but requires further elucidation. This article is part of a Special Issue entitled: Xenobiotic nuclear receptors: New Tricks for An Old Dog, edited by Dr. Wen Xie.

Polychlorinated biphenyls disrupt hepatic epidermal growth factor receptor signaling.

1. Polychlorinated biphenyls (PCBs) are persistent environmental pollutants that disrupt hepatic xenobiotic and intermediary metabolism, leading to metabolic syndrome and nonalcoholic steatohepatitis (NASH). 2. Since phenobarbital indirectly activates Constitutive Androstane Receptor (CAR) by antagonizing growth factor binding to the epidermal growth factor receptor (EGFR), we hypothesized that PCBs may also diminish EGFR signaling. 3. The effects of the PCB mixture Aroclor 1260 on the protein phosphorylation cascade triggered by EGFR activation were determined in murine (in vitro and in vivo) and human models (in vitro). EGFR tyrosine residue phosphorylation was decreased by PCBs in all models tested. 4. The IC50 values for Aroclor 1260 concentrations that decreased Y1173 phosphorylation of EGFR were similar in murine AML-12 and human HepG2 cells (∼2-4 µg/mL). Both dioxin and non-dioxin-like PCB congeners decreased EGFR phosphorylation in cell culture. 5. PCB treatment reduced phosphorylation of downstream EGFR effectors including Akt and mTOR, as well as other phosphoprotein targets including STAT3 and c-RAF in vivo. 6. PCBs diminish EGFR signaling in human and murine hepatocyte models and may dysregulate critical phosphoprotein regulators of energy metabolism and nutrition, providing a new mechanism of action in environmental diseases.

Inflammatory regulation of steroid sulfatase: A novel mechanism to control estrogen homeostasis and inflammation in chronic liver disease.

BACKGROUND & AIMS: Chronic inflammatory liver diseases are associated with estrogen excess and feminization in men, which is thought to be due to compromised liver function to break down estrogens. The goal of this study is to determine whether the inflammatory induction of steroid sulfatase (STS), which converts inactive estrogen sulfates to active estrogens, may have contributed to the estrogen excess in chronic liver disease. METHODS: We performed bioinformatic analysis, real-time PCR, immunohistochemistry, and UPLC/MS-MS to analyze hepatic STS expression and serum estrogen levels in patients with chronic liver diseases. The crosstalk between NF-κB pathway and STS-regulated estrogen signaling was investigated by electrophoretic mobility shift assay, chromatin immunoprecipitation, luciferase assay and gene knockdown experiments in human hepatocytes. RESULTS: Hepatic STS was induced in patients with chronic inflammatory liver diseases, which was accompanied by increased circulating estrogen levels. The human STS gene, but not the mouse Sts gene, was induced by inflammatory stimuli in hepatic cells. Mechanistically, STS was established as a novel NF-κB target gene, whose induction facilitated the conversion of inactive estrogen sulfates to active estrogens, and consequently attenuated the inflammatory response. In contrast, genetic or pharmacological inhibition of STS or a direct blockade of estrogen signaling sensitized liver cells to the transcriptional activation of NF-κB and inflammatory response, possibly through the inhibition of IκB kinase activation. CONCLUSIONS: Our results suggest a negative feedback loop in chronic inflammatory liver diseases, in which the inflammatory activation of NF-κB induces STS gene expression. The induced STS facilitates the conversion of inactive estrogen sulfates to active estrogens, which in return attenuates the NF-κB-mediated inflammation.

Simeprevir and sofosbuvir with or without ribavirin to treat recurrent genotype 1 hepatitis C virus infection after orthotopic liver transplantation.

Although combination simeprevir (SIM) plus sofosbuvir (SOF) is an approved regimen for genotype 1 chronic hepatitis C virus (HCV), data regarding its safety and efficacy in liver transplant recipients remain limited. A multicenter retrospective study was performed to determine the efficacy and tolerability of a 12-week regimen of SIM/SOF with or without ribavirin (RBV) in 56 consecutive liver transplant recipients in 2014; 79% of patients had genotype 1a, 14% had cirrhosis, and 73% were treatment experienced. Sustained virological response at 12 weeks (SVR12) was 88% by intention to treat analysis (95% confidence interval, 84%-90%). Four patients relapsed, but no on-treatment virological failures occurred. The Q80K polymorphism did not impact SVR12, but there was a trend toward decreased sustained virological response with advanced fibrosis (P = 0.18). HCV RNA was detectable at treatment week 4 in 21% of patients, and those who had detectable levels were less likely to achieve SVR12 (58% versus 95%; P = 0.003). Five patients had baseline Child-Pugh class B cirrhosis, and 2 of them died (1 following early discontinuation of therapy). An additional discontinuation resulted from a severe photosensitivity reaction in a patient on concomitant cyclosporine. Seven patients receiving RBV developed progressive anemia requiring intervention. Immunosuppression dose modifications were minimal. SIM/SOF for 12 weeks was effective and well tolerated by compensated liver transplant recipients especially when administered without concomitant RBV or cyclosporine. SIM/SOF appears to have a niche as the only 12-week RBV-free treatment regimen currently recommended by guidelines for compensated transplant recipients. However, 12 weeks may not be the optimal duration of therapy for those with detectable virus at week 4 or possibly for those with cirrhosis. These data require confirmation by prospective randomized clinical trials. Liver Transplantation 22 635-643 2016 AASLD.

Chronic Alcohol Consumption Causes Liver Injury in High-Fructose-Fed Male Mice Through Enhanced Hepatic Inflammatory Response.

BACKGROUND: Obesity and the metabolic syndrome occur in approximately one-third of patients with alcoholic liver disease (ALD). The increased consumption of fructose parallels the increased prevalence of obesity and the metabolic syndrome in the United States and worldwide. In this study, we investigated whether dietary high fructose potentiates chronic alcohol-induced liver injury, and explored potential mechanism(s). METHODS: Six-week-old male C57BL/6J mice were assigned to 4 groups: control, high fructose, chronic ethanol (EtOH), and high fructose plus chronic alcohol. The mice were fed either control diet or high-fructose diet (60%, w/w) for 18 weeks. Chronic alcohol-fed mice were given 20% (v/v) ethanol (Meadows-Cook model) ad libitum as the only available liquid from the 9th week through the 18th week. Liver injury, steatosis, hepatic inflammatory gene expression, and copper status were assessed. RESULTS: High-fructose diet and chronic alcohol consumption alone each induce hepatic fat accumulation and impair copper status. However, the combination of dietary high fructose plus chronic alcohol synergistically induced liver injury as evidenced by robustly increased plasma alanine aminotransferase and aspartate aminotransferase, but the combination did not exacerbate hepatic fat accumulation nor worsen copper status. Moreover, FE-fed mice were characterized by prominent microvesicular steatosis. High-fructose diet and chronic alcohol ingestion together led to a significant up-regulation of Kupffer cell (KC) M1 phenotype gene expression (e.g., tumor necrosis factor-α and monocyte chemoattractant protein-1), as well as Toll-like receptor 4 (TLR4) signaling gene expression, which is also associated with the up-regulation of KCs and activation marker gene expression, including Emr1, CD68, and CD163. CONCLUSIONS: Our data suggest that dietary high fructose may potentiate chronic alcohol consumption-induced liver injury. The underlying mechanism might be due to the synergistic effect of dietary high fructose and alcohol on the activation of the TLR4 signaling pathway, which in turn leads to KC activation and phenotype switch toward M1 polarization. This study suggests that alcohol-fructose combination contributes to ALD progression.