Interplay between early-life malnutrition, epigenetic modulation of the immune function and liver diseases.

Early-life nutrition plays a critical role in fetal growth and development. Food intake absence and excess are the two main types of energy malnutrition that predispose to the appearance of diseases in adulthood, according to the hypothesis of 'developmental origins of health and disease'. Epidemiological data have shown an association between early-life malnutrition and the metabolic syndrome in later life. Evidence has also demonstrated that nutrition during this period of life can affect the development of the immune system through epigenetic mechanisms. Thus, epigenetics has an essential role in the complex interplay between environmental factors and genetics. Altogether, this leads to the inflammatory response that is commonly seen in non-alcoholic fatty liver disease (NAFLD), the hepatic manifestation of the metabolic syndrome. In conjunction, DNA methylation, covalent modification of histones and the expression of non-coding RNA are the epigenetic phenomena that affect inflammatory processes in the context of NAFLD. Here, we highlight current understanding of the mechanisms underlying developmental programming of NAFLD linked to epigenetic modulation of the immune system and environmental factors, such as malnutrition.

Curcumin attenuates hepatic fibrosis and insulin resistance induced by bile duct ligation in rats.

Recent studies have strongly indicated the hepatoprotective effect of curcumin; however, the precise mechanisms are not well understood. This study aimed to determine the protective effect of curcumin on hepatic damage and hepatic insulin resistance in biliary duct ligated (BDL) fibrotic rat model. To accomplish this, male Wistar rats were divided into four groups (eight for each): sham group, BDL group, sham+Cur group and BDL+Cur group. The last two groups received curcumin at a dose of 100 mg/kg daily for 4 weeks. The mRNA/protein expression levels of Ras-related C3 botulinum toxin substrate 1 (Rac1), Rac1-GTP, dinucleotide phosphate oxidase 1 (NOX1), signal transducer and activator of transcription 3 (STAT3), suppressor of cytokine signalling 3 (SOCS3), insulin receptor substrate 1 (IRS1), extracellular signal-regulated kinase 1 (ERK1), specific protein 1 (Sp1) and hypoxia-inducible factor-1α (HIF-1α) were measured by real-time PCR and Western blotting, respectively. Fasting blood glucose, insulin and Leptin levels were determined and homoeostasis model assessment-estimated insulin resistance, as an index of insulin resistance, was calculated. Curcumin significantly attenuated liver injury and fibrosis, including amelioration of liver histological changes, reduction of hepatic enzymes, as well as decreased expression of liver fibrogenesis-associated variables, including Rac1, Rac1-GTP, NOX1, ERK1, HIF-1α and Sp1. Curcumin also attenuated leptin level and insulin resistance, which had increased in BDL rats (P<0·05). Furthermore, compared with the BDL group, we observed an increase in IRS1 and a decrease in SOCS3 and STAT3 expression in the curcumin-treated BDL group (P<0·05), indicating return of these parameters towards normalcy. In conclusion, Curcumin showed hepatoprotective activity against BDL-induced liver injury and hepatic insulin resistance by influencing the expression of some genes/proteins involved in these processes, and the results suggest that it can be used as a therapeutic option.

Vitamin A Reduces the Mortality of Animals with Induced Liver Fibrosis by Providing a Multi-level Body Defense System.

Background: Liver diseases remain the most important medical and biological problem. Works devoted to the study of the vitamin A role have shown conflicting results of its effect on the fibrosis development. We tested the hypothesis that an increase of the copper content in the liver, an example of which is Wilson's disease, shifts the balance in the redox system towards pro-oxidants, which leads to the antioxidant systems inhibition, including a decrease in the vitamin A content; this affects the levels of liver function regulation and the development of fibrosis. Methods: In animals with Cu-induced liver fibrosis, neutrophil activity, the immunocompetent cells content, the activity of alanine aminotransferase and γ-glutamylaminotransferase, the content of urea and creatinine in blood serum, as well as the vitamin A content in the liver, copper ions and its regenerative potential were determined. Results: It was found that three consecutive injections of copper sulfate to animals with an interval of 48 h between injections led to the death of 40% of the animals, and 60% showed resistance. The content of vitamin A in "resistant" animals at the beginning of the development of the fibrosis was reduced by 4 times compared to the control, the functional activity of the liver was somewhat reduced, and a connective tissue capsule was formed around the liver lobes in 75% of the animals. If animals with the initial stage of liver fibrosis received daily vitamin A at a dose of 300 IU/100 g of body weight, which was accompanied by its multiple increase in the liver (15 times on day 14), the mortality of animals decreased by almost 7 times, the functional activity of the liver did not differ from control. In the blood of these animals, the number of leukocytes, granulocytes, and monocytes was increased and phagocytic activity was increased. At the same time, the connective tissue capsule was developed more intensively than in animals receiving only copper sulfate, and was detected in 91% of the animals. Fragments of the liver, even more than in the case of fibrosis, lost the ability to regenerate in culture. Conclusion: We came to the conclusion that vitamin A leads to the connective tissue "specialization" formation of the liver and triggers vicious circles of metabolism and includes several levels of regulation systems. Further studies of the vitamin A effect mechanisms on the liver with fibrosis will allow the use of this antioxidant in the treatment.

Stellate cell expression of SPARC-related modular calcium-binding protein 2 is associated with human non-alcoholic fatty liver disease severity.

Background & Aims: Histological assessment of liver biopsies is the gold standard for diagnosis of non-alcoholic steatohepatitis (NASH), the progressive form of non-alcoholic fatty liver disease (NAFLD), despite its well-established limitations. Therefore, non-invasive biomarkers that can offer an integrated view of the liver are needed to improve diagnosis and reduce sampling bias. Hepatic stellate cells (HSCs) are central in the development of hepatic fibrosis, a hallmark of NASH. Secreted HSC-specific proteins may, therefore, reflect disease state in the NASH liver and serve as non-invasive diagnostic biomarkers. Methods: We performed RNA-sequencing on liver biopsies from a histologically characterised cohort of obese patients (n = 30, BMI >35 kg/m2) to identify and evaluate HSC-specific genes encoding secreted proteins. Bioinformatics was used to identify potential biomarkers and their expression at single-cell resolution. We validated our findings using single-molecule fluorescence in situ hybridisation (smFISH) and ELISA to detect mRNA in liver tissue and protein levels in plasma, respectively. Results: Hepatic expression of SPARC-related modular calcium-binding protein 2 (SMOC2) was increased in NASH compared to no-NAFLD (p.adj <0.001). Single-cell RNA-sequencing data indicated that SMOC2 was primarily expressed by HSCs, which was validated using smFISH. Finally, plasma SMOC2 was elevated in NASH compared to no-NAFLD (p <0.001), with a predictive accuracy of AUROC 0.88. Conclusions: Increased SMOC2 in plasma appears to reflect HSC activation, a key cellular event associated with NASH progression, and may serve as a non-invasive biomarker of NASH. Impact and implications: Non-alcoholic fatty liver disease (NAFLD) and its progressive form, non-alcoholic steatohepatitis (NASH), are the most common forms of chronic liver diseases. Currently, liver biopsies are the gold standard for diagnosing NAFLD. Blood-based biomarkers to complement liver biopsies for diagnosis of NAFLD are required. We found that activated hepatic stellate cells, a cell type central to NAFLD pathogenesis, upregulate expression of the secreted protein SPARC-related modular calcium-binding protein 2 (SMOC2). SMOC2 was elevated in blood samples from patients with NASH and may hold promise as a blood-based biomarker for the diagnosis of NAFLD.

PPAR agonists for the treatment of primary biliary cholangitis: Old and new tales.

Introduction: Primary biliary cholangitis (PBC) is an autoimmune liver disease involving the small intrahepatic bile ducts; when untreated or undertreated, it may evolve to liver fibrosis and cirrhosis. Ursodeoxycholic Acid (UDCA) is the standard of care treatment, Obeticholic Acid (OCA) has been approved as second-line therapy for those non responder or intolerant to UDCA. However, due to moderate rate of UDCA-non responders and to warnings recently issued against OCA use in patients with cirrhosis, further therapies are needed.Areas covered. Deep investigations into the pathogenesis of PBC is leading to proposal of new therapeutic agents, among which peroxisome proliferator-activated receptor (PPAR) ligands seem to be highly promising given the preliminary, positive results in Phase 2 and 3 trials. Bezafibrate, the most evaluated, is currently used in clinical practice in combination with UDCA in referral centers. We herein describe completed and ongoing trials involving PPAR agonists use in PBC, analyzing pits and falls. Expert opinion: Testing new therapeutic opportunities in PBC is challenging due to its low prevalence and slow progression. However, new drugs including PPAR agonists, are currently under investigation and should be considered for at-risk PBC patients.

Molecular characterization of chronic liver disease dynamics: From liver fibrosis to acute-on-chronic liver failure.

Background & Aims: The molecular mechanisms driving the progression from early-chronic liver disease (CLD) to cirrhosis and, finally, acute-on-chronic liver failure (ACLF) are largely unknown. Our aim was to develop a protein network-based approach to investigate molecular pathways driving progression from early-CLD to ACLF. Methods: Transcriptome analysis was performed on liver biopsies from patients at different liver disease stages, including fibrosis, compensated cirrhosis, decompensated cirrhosis and ACLF, and control healthy livers. We created 9 liver-specific disease-related protein-protein interaction networks capturing key pathophysiological processes potentially related to CLD. We used these networks as a framework and performed gene set-enrichment analysis (GSEA) to identify dynamic gene profiles of disease progression. Results: Principal component analyses revealed that samples clustered according to the disease stage. GSEA of the defined processes showed an upregulation of inflammation, fibrosis and apoptosis networks throughout disease progression. Interestingly, we did not find significant gene expression differences between compensated and decompensated cirrhosis, while ACLF showed acute expression changes in all the defined liver disease-related networks. The analyses of disease progression patterns identified ascending and descending expression profiles associated with ACLF onset. Functional analyses showed that ascending profiles were associated with inflammation, fibrosis, apoptosis, senescence and carcinogenesis networks, while descending profiles were mainly related to oxidative stress and genetic factors. We confirmed by qPCR the upregulation of genes of the ascending profile and validated our findings in an independent patient cohort. Conclusion: ACLF is characterized by a specific hepatic gene expression pattern related to inflammation, fibrosis, apoptosis, senescence and carcinogenesis. Moreover, the observed profile is significantly different from that of compensated and decompensated cirrhosis, supporting the hypothesis that ACLF should be considered a distinct entity. Lay summary: By using transjugular biopsies obtained from patients at different stages of chronic liver disease, we unveil the molecular pathogenic mechanisms implicated in the progression of chronic liver disease to cirrhosis and acute-on-chronic liver failure. The most relevant finding in this study is that patients with acute-on-chronic liver failure present a specific hepatic gene expression pattern distinct from that of patients at earlier disease stages. This gene expression pattern is mostly related to inflammation, fibrosis, angiogenesis, and senescence and apoptosis pathways in the liver.

Pathogenesis of Alcohol-Associated Liver Disease.

Excessive alcohol consumption is a global healthcare problem with enormous social, economic, and clinical consequences. While chronic, heavy alcohol consumption causes structural damage and/or disrupts normal organ function in virtually every tissue of the body, the liver sustains the greatest damage. This is primarily because the liver is the first to see alcohol absorbed from the gastrointestinal tract via the portal circulation and second, because the liver is the principal site of ethanol metabolism. Alcohol-induced damage remains one of the most prevalent disorders of the liver and a leading cause of death or transplantation from liver disease. Despite extensive research on the pathophysiology of this disease, there are still no targeted therapies available. Given the multifactorial mechanisms for alcohol-associated liver disease pathogenesis, it is conceivable that a multitherapeutic regimen is needed to treat different stages in the spectrum of this disease.

Alcohol-associated liver disease: A review on its pathophysiology, diagnosis and drug therapy.

One of the global burdens of health care is an alcohol-associated liver disease (ALD) and liver-related death which is caused due to acute or chronic consumption of alcohol. Chronic consumption of alcohol damage the normal defense mechanism of the liver and likely to disturb the gut barrier system, mucosal immune cells, which leads to decreased nutrient absorption. Therapy of ALD depends upon the spectrum of liver injury that causes fatty liver, hepatitis, and cirrhosis. The foundation of therapy starts with abstinence from alcohol. Corticosteroids are used for the treatment of ALD but due to poor acceptance, continuing mortality, and identification of tumor necrosis factor-alpha as an integral component in pathogenesis, recent studies focus on pentoxifylline and, antitumor necrosis factor antibody to neutralize cytokines in the therapy of severe alcoholic hepatitis. Antioxidants also play a significant role in the treatment but till today there is no universally accepted therapy available for any stage of ALD. The treatment aspects need to restore the gut functions and require nutrient-based treatments to regulate the functions of the gut system and prevent liver injury. The vital action of saturated fatty acids greatly controls the gut barrier. Overall, this review mainly focuses on the mechanism of alcohol-induced metabolic dysfunction, contribution to liver pathogenesis, the effect of pregnancy, and targeted therapy of ALD.

Genetic predisposition similarities between NASH and ASH: Identification of new therapeutic targets.

Fatty liver disease can be triggered by a combination of excess alcohol, dysmetabolism and other environmental cues, which can lead to steatohepatitis and can evolve to acute/chronic liver failure and hepatocellular carcinoma, especially in the presence of shared inherited determinants. The recent identification of the genetic causes of steatohepatitis is revealing new avenues for more effective risk stratification. Discovery of the mechanisms underpinning the detrimental effect of causal mutations has led to some breakthroughs in the comprehension of the pathophysiology of steatohepatitis. Thanks to this approach, hepatocellular fat accumulation, altered lipid droplet remodelling and lipotoxicity have now taken centre stage, while the role of adiposity and gut-liver axis alterations have been independently validated. This process could ignite a virtuous research cycle that, starting from human genomics, through omics approaches, molecular genetics and disease models, may lead to the development of new therapeutics targeted to patients at higher risk. Herein, we also review how this knowledge has been applied to: a) the study of the main PNPLA3 I148M risk variant, up to the stage of the first in-human therapeutic trials; b) highlight a role of MBOAT7 downregulation and lysophosphatidyl-inositol in steatohepatitis; c) identify IL-32 as a candidate mediator linking lipotoxicity to inflammation and liver disease. Although this precision medicine drug discovery pipeline is mainly being applied to non-alcoholic steatohepatitis, there is hope that successful products could be repurposed to treat alcohol-related liver disease as well.

New targets for NAFLD.

Non-alcoholic fatty liver disease (NAFLD) is a growing cause of chronic liver disease worldwide. It is characterised by steatosis, liver inflammation, hepatocellular injury and progressive fibrosis. Several preclinical models (dietary and genetic animal models) of NAFLD have deepened our understanding of its aetiology and pathophysiology. Despite the progress made, there are currently no effective treatments for NAFLD. In this review, we will provide an update on the known molecular pathways involved in the pathophysiology of NAFLD and on ongoing studies of new therapeutic targets.

Boosting mitochondria activity by silencing MCJ overcomes cholestasis-induced liver injury.

BACKGROUND & AIMS: Mitochondria are the major organelles for the formation of reactive oxygen species (ROS) in the cell, and mitochondrial dysfunction has been described as a key factor in the pathogenesis of cholestatic liver disease. The methylation-controlled J-protein (MCJ) is a mitochondrial protein that interacts with and represses the function of complex I of the electron transport chain. The relevance of MCJ in the pathology of cholestasis has not yet been explored. METHODS: We studied the relationship between MCJ and cholestasis-induced liver injury in liver biopsies from patients with chronic cholestatic liver diseases, and in livers and primary hepatocytes obtained from WT and MCJ-KO mice. Bile duct ligation (BDL) was used as an animal model of cholestasis, and primary hepatocytes were treated with toxic doses of bile acids. We evaluated the effect of MCJ silencing for the treatment of cholestasis-induced liver injury. RESULTS: Elevated levels of MCJ were detected in the liver tissue of patients with chronic cholestatic liver disease when compared with normal liver tissue. Likewise, in mouse models, the hepatic levels of MCJ were increased. After BDL, MCJ-KO animals showed significantly decreased inflammation and apoptosis. In an in vitro model of bile-acid induced toxicity, we observed that the loss of MCJ protected mouse primary hepatocytes from bile acid-induced mitochondrial ROS overproduction and ATP depletion, enabling higher cell viability. Finally, the in vivo inhibition of the MCJ expression, following BDL, showed reduced liver injury and a mitigation of the main cholestatic characteristics. CONCLUSIONS: We demonstrated that MCJ is involved in the progression of cholestatic liver injury, and our results identified MCJ as a potential therapeutic target to mitigate the liver injury caused by cholestasis. LAY SUMMARY: In this study, we examine the effect of mitochondrial respiratory chain inhibition by MCJ on bile acid-induced liver toxicity. The loss of MCJ protects hepatocytes against apoptosis, mitochondrial ROS overproduction, and ATP depletion as a result of bile acid toxicity. Our results identify MCJ as a potential therapeutic target to mitigate liver injury in cholestatic liver diseases.

Our emerging understanding of the roles of long non-coding RNAs in normal liver function, disease, and malignancy.

Long non-coding RNAs (lncRNAs) are important biological mediators that regulate numerous cellular processes. New experimental evidence suggests that lncRNAs play essential roles in liver development, normal liver physiology, fibrosis, and malignancy, including hepatocellular carcinoma and cholangiocarcinoma. In this review, we summarise our current understanding of the function of lncRNAs in the liver in both health and disease, as well as discuss approaches that could be used to target these non-coding transcripts for therapeutic purposes.

Liver fibrosis and CD206+ macrophage accumulation are suppressed by anti-GM-CSF therapy.

BACKGROUND & AIMS: Chronic liver inflammation leads to fibrosis and cirrhosis and is associated with an accumulation of intrahepatic TNFα-secreting CD206+ macrophages, which may participate in maintaining chronic liver disease in a GM-CSF-dependent manner. We aimed to elucidate the exact role of GM-CSF in the development and progression of chronic liver disease. METHODS: Liver immunohistochemistry and serum quantification were performed in patients with viral and non-viral-related liver disease to compare CD206+ monocyte/macrophages, fibrosis and GM-CSF. This was followed by functional validations in vitro and in vivo in humanised mice. RESULTS: Using multiplex immunofluorescence and histo-cytometry, we show that highly fibrotic livers had a greater density of CD206+ macrophages that produced more TNFα and GM-CSF in the non-tumour liver regions of patients with hepatocellular carcinoma (n = 47), independent of aetiology. In addition, the absolute number of CD206+ macrophages strongly correlated with the absolute number of GM-CSF-producing macrophages. In non-HCC chronic HCV+ patients (n = 40), circulating GM-CSF levels were also increased in proportion to the degree of liver fibrosis and serum viral titres. We then demonstrated in vitro that monocytes converted to TNFα-producing CD206+ macrophage-like cells in response to bacterial products (lipopolysaccharide) in a GM-CSF-dependent manner, confirming the in vivo normalisation of serum GM-CSF concentration following oral antibiotic treatment observed in HBV-infected humanised mice. Finally, anti-GM-CSF neutralising antibody treatment reduced intrahepatic CD206+ macrophage accumulation and abolished liver fibrosis in HBV-infected humanised mice. CONCLUSIONS: While the direct involvement of CD206+ macrophages in liver fibrosis remains to be demonstrated, these findings show that GM-CSF may play a central role in liver fibrosis and could guide the development of anti-GM-CSF antibody-based therapy for the management of patients with chronic liver disease. LAY SUMMARY: Liver fibrosis is a major driver of liver disease progression. Herein, we have shown that granulocyte-macrophage colony-stimulating factor (GM-CSF) plays an important role in the development of liver fibrosis. Our findings support the use of anti-GM-CSF neutralising antibodies for the management of patients with chronic liver disease resulting from both viral and non-viral causes.

Hot water extract of turmeric (Curcuma longa) prevents non-alcoholic steatohepatitis in mice by inhibiting hepatic oxidative stress and inflammation.

Curcuma longa, also known as turmeric, has long been used as a medicinal herb with various biological effects. A hot water extract of C. longa (WEC) has been reported to show antioxidant and anti-inflammatory activity, but its effect on hepatic inflammation is poorly understood. In the present study, to investigate the effect of WEC on non-alcoholic steatohepatitis, C57BL/6J mice were fed a low-methionine, choline-deficient diet with 0·175 % WEC (WEC group) or without WEC (control group) for 6 or 12 weeks. Although hepatic steatosis was similar in the WEC group and the control group, WEC suppressed the elevation of plasma aspartate aminotransferase and alanine aminotransferase, which are markers of hepatocellular damage. Compared with the control group, the WEC group had higher hepatic levels of reduced glutathione and superoxide dismutase, as well as a lower hepatic level of thiobarbituric acid-reactive substances. WEC also reduced hepatic expression of mRNA for inflammatory factors, including TNF-α, IL-1ß, IL-6, monocyte chemoattractant protein-1, vascular cell adhesion molecule-1, F4/80 and CC motif chemokine receptor 2. Histological examination revealed that WEC suppressed hepatic recruitment of F4/80+ monocytes/macrophages and inhibited hepatic fibrosis. Furthermore, WEC inhibited hepatic expression of mRNA for molecules related to fibrosis, such as transforming growth factor-ß, α-smooth muscle actin, type I collagen (α1-chain) and tissue inhibitor of matrix metalloproteinase-1. These findings suggest that dietary intake of WEC prevents the progression of non-alcoholic steatohepatitis by alleviating hepatic oxidative stress and inflammation.

Oxidative stress and cell damage in a model of precancerous lesions and advanced hepatocellular carcinoma in rats.

Hepatocellular carcinoma (HCC) is the third most frequent cause of cancer deaths throughout the world. This study was aimed to analyze oxidative stress and cell damage in a multistage model of liver carcinogenesis induced by diethylnitrosamine (DEN) in rats. Male Wistar rats weighing 145-150 g were divided into three groups: control, precancerous lesions (PL) (which received 100 mg DEN once a week every 6 weeks up to 28 weeks), and advanced HCC (50 mg DEN once/twice per week up to 19 weeks). Lipid peroxidation (TBARS), superoxide dismutase (SOD) activity, and expression of transforming growth factor-1 beta (TGF)-1ß, endothelial and inducible nitric oxide syntahese (eNOS, iNOS), NADPH quinone oxireductase (NQO)-1, nuclear factor erythroid 2-related factor (NrF)2, kelch-like ECH-associated protein (Keap)1 and heat shock protein (HSP)70 were measured. TBARS concentration was augmented in the PL and advanced HCC groups. SOD activity, TGF-1ß and Nrf2 expression were higher in animals with precancerous lesions. In advanced HCC, expression of NQO1 and iNOS increased while there was a decrease in HPS70 expression. Data obtained provide evidence for the differential activation of proteins involved in oxidative stress and cell damage during progression of carcinogenesis in an animal model of HCC.

Autophagy and apoptosis in liver injury.

Apoptosis is a primary characteristic in the pathogenesis of liver disease. Hepatic apoptosis is regulated by autophagic activity. However, mechanisms mediating their interaction remain to be determined. Basal level of autophagy ensures the physiological turnover of old and damaged organelles. Autophagy also is an adaptive response under stressful conditions. Autophagy can control cell fate through different cross-talk signals. A complex interplay between hepatic autophagy and apoptosis determines the degree of hepatic apoptosis and the progression of liver disease as demonstrated by pre-clinical models and clinical trials. This review summarizes recent advances on roles of autophagy that plays in pathophysiology of liver. The autophagic pathway can be a novel therapeutic target for liver disease.

The Riddle of Nonalcoholic Fatty Liver Disease: Progression From Nonalcoholic Fatty Liver to Nonalcoholic Steatohepatitis.

Nonalcoholic fatty liver (NAFL) is an emerging global epidemic which progresses to nonalcoholic steatohepatitis (NASH) and cirrhosis in a subset of subjects. Various reviews have focused on the etiology, epidemiology, pathogenesis and treatment of NAFLD. This review highlights specifically the triggers implicated in disease progression from NAFL to NASH. The integrating role of genes, dietary factors, innate immunity, cytokines and gut microbiome have been discussed.

Autophagy modulation as a potential therapeutic target for liver diseases.

Autophagy is a critical intracellular pathway which maintains cellular function by lysosomal degradation of damaged proteins and organelles besides elimination of invading pathogens. Its primary function is to prevent cell death. Autophagy has diverse physiological functions namely; starvation adaptation, prevention of tumorigenesis, energy homeostasis, intracellular quality control and degradation of abnormal intracellular protein aggregates. Understanding the molecular mechanisms of autophagy has given key insights into the pathogenesis of various diseases like Non Alcoholic Steato-Hepatitis, Hepatitis B and C infections, Alpha-1 antitrypsin deficiency and hepatocellular carcinoma. Pharmacological modulation of autophagy may have a therapeutic potential in management of these liver diseases.