Alcohol-Associated Liver Disease Outcomes: Critical Mechanisms of Liver Injury Progression

Alcohol-associated liver disease (ALD) is a substantial cause of morbidity and mortality worldwide and represents a spectrum of liver injury beginning with hepatic steatosis (fatty liver) progressing to inflammation and culminating in cirrhosis. Multiple factors contribute to ALD progression and disease severity. Here, we overview several crucial mechanisms related to ALD end-stage outcome development, such as epigenetic changes, cell death, hemolysis, hepatic stellate cells activation, and hepatic fatty acid binding protein 4. Additionally, in this review, we also present two clinically relevant models using human precision-cut liver slices and hepatic organoids to examine ALD pathogenesis and progression.

Human Precision-Cut Liver Slices: A Potential Platform to Study Alcohol-Related Liver Disease

Alcohol-related liver disease (ALD) encompasses a range of pathological conditions that are complex to study at the clinical and preclinical levels. Despite the global burden of ALD, there is a lack of effective treatments, and mortality is high. One of the reasons for the unsuccessful development of novel therapies is that experimental studies are hindered by the challenge of recapitulating this multifactorial disorder in vitro, including the contributions of hepatotoxicity, impaired lipid metabolism, fibrosis and inflammatory cytokine storm, which are critical drivers in the pathogenesis of ALD in patients and primary targets for drug development. Here, we present the unique characteristics of the culture of human precision-cut liver slices (PCLS) to replicate key disease processes in ALD. PCLS were prepared from human liver specimens and treated with ethanol alone or in combination with fatty acids and lipopolysaccharide (FA + LPS) for up to 5 days to induce hepatotoxic, inflammatory and fibrotic events associated with ALD. Alcohol insult induced hepatocyte death which was more pronounced with the addition of FA + LPS. This mixture showed a significant increase in the cytokines conventionally associated with the prototypical inflammatory response observed in severe ALD, and interestingly, alcohol alone exhibited a different effect. Profibrogenic activation was also observed in the slices and investigated in the context of slice preparation. These results support the versatility of this organotypic model to study different pathways involved in alcohol-induced liver damage and ALD progression and highlight the applicability of the PCLS for drug discovery, confirming their relevance as a bridge between preclinical and clinical studies.

Giant mitochondria in human liver disease

This thematic review aims to provide an overview of the current state of knowledge about the occurrence of giant mitochondria or megamitochondria in liver parenchymal cells. Their presence and accumulation are considered to be a major pathological hallmark of the health and fate of liver parenchymal cells that leads to overall tissue deterioration and eventually results in organ failure. The first description on giant mitochondria dates back to the 1960s, coinciding with the availability of the first generation of electron microscopes in clinical diagnostic laboratories. Detailed accounts on their ultrastructure have mostly been described in patients suffering from alcoholic liver disease, chronic hepatitis, hepatocellular carcinoma and non-alcoholic fatty liver disease. Interestingly, from this extensive literature survey, it became apparent that giant mitochondria or megamitochondria present themselves with or without highly organised crystal-like intramitochondrial inclusions. The origin, formation and potential role of giant mitochondria remain to-date largely unanswered. Likewise, the biochemical composition of the well-organised crystal-like inclusions and their possible impact on mitochondrial function is unclear. Herein, concepts about the possible mechanism of their formation and three-dimensional architecture will be approached. We will furthermore discuss their importance in diagnostics, including future research outlooks and potential therapeutic interventions to cure liver disease where giant mitochondria are implemented.

Patient-derived precision cut tissue slices from primary liver cancer as a potential platform for preclinical drug testing

BACKGROUND

The exploitation of anti-tumour immunity, harnessed through immunomodulatory therapies, has fundamentally changed the treatment of primary liver cancer (PLC). However, this has posed significant challenges in preclinical research. Novel immunologically relevant models for PLC are urgently required to improve the translation from bench to bedside and back, explore and predict effective combinatorial therapies, aid novel drug discovery and develop personalised treatment modalities.

METHODS

We used human precision-cut tissue slices (PCTS) derived from resected tumours to create a patient-specific immunocompetent disease model that captures the multifaceted and intricate heterogeneity of the tumour and the tumour microenvironment. Tissue architecture, tumour viability and treatment response to single agent and combination therapies were assessed longitudinally over 8 days of ex vivo culture by histological analysis, detection of proliferation/cell death markers, ATP content via HPLC. Immune cell infiltrate was assessed using PCR and immunofluorescence. Checkpoint receptor expression was quantified via Quantigene RNA assay.

FINDINGS

After optimising the culture conditions, PCTS maintained the original tissue architecture, including tumour morphology, stroma and tumour-infiltrated leukocytes. Moreover, PCTS retained the tumour-specific immunophenotype over time, suggesting the utility of PCTS to investigate immunotherapeutic drug efficacy and identify non-responsiveness.

INTERPRETATION

Here we have characterised the PCTS model and demonstrated its effectiveness as a robust preclinical tool that will significantly support the development of successful (immuno)therapeutic strategies for PLC.

FUNDING

Foundation for Liver Research, London.

Serological response and breakthrough infection after COVID-19 vaccination in patients with cirrhosis and post-liver transplant

BACKGROUND

Vaccine hesitancy and lack of access remain major issues in disseminating COVID-19 vaccination to liver patients globally. Factors predicting poor response to vaccination and risk of breakthrough infection are important data to target booster vaccine programs. The primary aim of the current study was to measure humoral responses to 2 doses of COVID-19 vaccine. Secondary aims included the determination of factors predicting breakthrough infection.

METHODS

COVID-19 vaccination and Biomarkers in cirrhosis And post-Liver Transplantation is a prospective, multicenter, observational case-control study. Participants were recruited at 4-10 weeks following first and second vaccine doses in cirrhosis [n = 325; 94% messenger RNA (mRNA) and 6% viral vaccine], autoimmune liver disease (AILD) (n = 120; 77% mRNA and 23% viral vaccine), post-liver transplant (LT) (n = 146; 96% mRNA and 3% viral vaccine), and healthy controls (n = 51; 72% mRNA, 24% viral and 4% heterologous combination). Serological end points were measured, and data regarding breakthrough SARS-CoV-2 infection were collected.

RESULTS

After adjusting by age, sex, and time of sample collection, anti-Spike IgG levels were the lowest in post-LT patients compared to cirrhosis (p < 0.0001), AILD (p < 0.0001), and control (p = 0.002). Factors predicting reduced responses included older age, Child-Turcotte-Pugh B/C, and elevated IL-6 in cirrhosis; non-mRNA vaccine in AILD; and coronary artery disease, use of mycophenolate and dysregulated B-call activating factor, and lymphotoxin-α levels in LT. Incident infection occurred in 6.6%, 10.6%, 7.4%, and 15.6% of cirrhosis, AILD, post-LT, and control, respectively. The only independent factor predicting infection in cirrhosis was low albumin level.

CONCLUSIONS

LT patients present the lowest response to the SARS-CoV-2 vaccine. In cirrhosis, the reduced response is associated with older age, stage of liver disease and systemic inflammation, and breakthrough infection with low albumin level.

Interaction between estrogen receptor-α and PNPLA3 p.I148M variant drives fatty liver disease susceptibility in women

Fatty liver disease (FLD) caused by metabolic dysfunction is the leading cause of liver disease and the prevalence is rising, especially in women. Although during reproductive age women are protected against FLD, for still unknown and understudied reasons some develop rapidly progressive disease at the menopause. The patatin-like phospholipase domain-containing 3 (PNPLA3) p.I148M variant accounts for the largest fraction of inherited FLD variability. In the present study, we show that there is a specific multiplicative interaction between female sex and PNPLA3 p.I148M in determining FLD in at-risk individuals (steatosis and fibrosis, P < 10-10; advanced fibrosis/hepatocellular carcinoma, P = 0.034) and in the general population (P < 10-7 for alanine transaminase levels). In individuals with obesity, hepatic PNPLA3 expression was higher in women than in men (P = 0.007) and in mice correlated with estrogen levels. In human hepatocytes and liver organoids, PNPLA3 was induced by estrogen receptor-α (ER-α) agonists. By chromatin immunoprecipitation and luciferase assays, we identified and characterized an ER-α-binding site within a PNPLA3 enhancer and demonstrated via CRISPR-Cas9 genome editing that this sequence drives PNPLA3 p.I148M upregulation, leading to lipid droplet accumulation and fibrogenesis in three-dimensional multilineage spheroids with stellate cells. These data suggest that a functional interaction between ER-α and PNPLA3 p.I148M variant contributes to FLD in women.

A Pathogenic Role of Non-Parenchymal Liver Cells in Alcohol-Associated Liver Disease of Infectious and Non-Infectious Origin

Now, much is known regarding the impact of chronic and heavy alcohol consumption on the disruption of physiological liver functions and the induction of structural distortions in the hepatic tissues in alcohol-associated liver disease (ALD). This review deliberates the effects of alcohol on the activity and properties of liver non-parenchymal cells (NPCs), which are either residential or infiltrated into the liver from the general circulation. NPCs play a pivotal role in the regulation of organ inflammation and fibrosis, both in the context of hepatotropic infections and in non-infectious settings. Here, we overview how NPC functions in ALD are regulated by second hits, such as gender and the exposure to bacterial or viral infections. As an example of the virus-mediated trigger of liver injury, we focused on HIV infections potentiated by alcohol exposure, since this combination was only limitedly studied in relation to the role of hepatic stellate cells (HSCs) in the development of liver fibrosis. The review specifically focusses on liver macrophages, HSC, and T-lymphocytes and their regulation of ALD pathogenesis and outcomes. It also illustrates the activation of NPCs by the engulfment of apoptotic bodies, a frequent event observed when hepatocytes are exposed to ethanol metabolites and infections. As an example of such a double-hit-induced apoptotic hepatocyte death, we deliberate on the hepatotoxic accumulation of HIV proteins, which in combination with ethanol metabolites, causes intensive hepatic cell death and pro-fibrotic activation of HSCs engulfing these HIV- and malondialdehyde-expressing apoptotic hepatocytes.

Reduced circulating FABP2 in patients with moderate to severe COVID-19 may indicate enterocyte functional change rather than cell death

The gut is of importance in the pathology of COVID-19 both as a route of infection, and gut dysfunction influencing the severity of disease. Systemic changes caused by SARS-CoV-2 gut infection include alterations in circulating levels of metabolites, nutrients and microbial products which alter immune and inflammatory responses. Circulating plasma markers for gut inflammation and damage such as zonulin, lipopolysaccharide and β-glycan increase in plasma along with severity of disease. However, Intestinal Fatty Acid Binding Protein / Fatty Acid Binding Protein 2 (I-FABP/FABP2), a widely used biomarker for gut cell death, has paradoxically been shown to be reduced in moderate to severe COVID-19. We also found this pattern in a pilot cohort of mild (n = 18) and moderately severe (n = 19) COVID-19 patients in Milan from March to June 2020. These patients were part of the first phase of COVID-19 in Europe and were therefore all unvaccinated. After exclusion of outliers, patients with more severe vs milder disease showed reduced FABP2 levels (median [IQR]) (124 [368] vs. 274 [558] pg/mL, P < 0.01). A reduction in NMR measured plasma relative lipid-CH3 levels approached significance (median [IQR]) (0.081 [0.011] vs. 0.073 [0.024], P = 0.06). Changes in circulating lipid levels are another feature commonly observed in severe COVID-19 and a weak positive correlation was observed in the more severe group between reduced FABP2 and reduced relative lipid-CH3 and lipid-CH2 levels. FABP2 is a key regulator of enterocyte lipid import, a process which is inhibited by gut SARS-CoV-2 infection. We propose that the reduced circulating FABP2 in moderate to severe COVID-19 is a marker of infected enterocyte functional change rather than gut damage, which could also contribute to the development of hypolipidemia in patients with more severe disease.

Novel therapeutic strategies for Chronic Hepatitis B

The last few years have seen a resurgence of activity in the hepatitis B drug pipeline, with many compounds in various stages of development. This review aims to provide a comprehensive overview of the latest advances in therapeutics for chronic hepatitis B (CHB). We will discuss the broad spectrum of direct-acting antivirals in clinical development, including capsids inhibitors, siRNA, HBsAg and polymerase inhibitors. In addition, host-targeted therapies (HTT) will be extensively reviewed, focusing on the latest progress in immunotherapeutics such as toll-like receptors and RIG-1 agonists, therapeutic vaccines and immune checkpoints modulators. A growing number of HTT in pre-clinical development directly target the key to HBV persistence, namely the covalently closed circular DNA (cccDNA) and hold great promise for HBV cure. This exciting area of HBV research will be highlighted, and molecules such as cyclophilins inhibitors, APOBEC3 deaminases and epigenetic modifiers will be discussed.

Acetyl-CoA metabolism drives epigenome change and contributes to carcinogenesis risk in fatty liver disease

BACKGROUND

The incidence of non-alcoholic fatty liver disease (NAFLD)-associated hepatocellular carcinoma (HCC) is increasing worldwide, but the steps in precancerous hepatocytes which lead to HCC driver mutations are not well understood. Here we provide evidence that metabolically driven histone hyperacetylation in steatotic hepatocytes can increase DNA damage to initiate carcinogenesis.

METHODS

Global epigenetic state was assessed in liver samples from high-fat diet or high-fructose diet rodent models, as well as in cultured immortalized human hepatocytes (IHH cells). The mechanisms linking steatosis, histone acetylation and DNA damage were investigated by computational metabolic modelling as well as through manipulation of IHH cells with metabolic and epigenetic inhibitors. Chromatin immunoprecipitation and next-generation sequencing (ChIP-seq) and transcriptome (RNA-seq) analyses were performed on IHH cells. Mutation locations and patterns were compared between the IHH cell model and genome sequence data from preneoplastic fatty liver samples from patients with alcohol-related liver disease and NAFLD.

RESULTS

Genome-wide histone acetylation was increased in steatotic livers of rodents fed high-fructose or high-fat diet. In vitro, steatosis relaxed chromatin and increased DNA damage marker γH2AX, which was reversed by inhibiting acetyl-CoA production. Steatosis-associated acetylation and γH2AX were enriched at gene clusters in telomere-proximal regions which contained HCC tumour suppressors in hepatocytes and human fatty livers. Regions of metabolically driven epigenetic change also had increased levels of DNA mutation in non-cancerous tissue from NAFLD and alcohol-related liver disease patients. Finally, genome-scale network modelling indicated that redox balance could be a key contributor to this mechanism.

CONCLUSIONS

Abnormal histone hyperacetylation facilitates DNA damage in steatotic hepatocytes and is a potential initiating event in hepatocellular carcinogenesis.

A permeability assay for mouse intestinal organoids

Here, we describe an assay for intestinal permeability in mouse intestinal organoids, although this may also be adapted for other species. Propidium iodide (PI) does not penetrate intact biological membranes and thus cannot enter the lumen of intact organoids. Passage of PI within the lumen can be induced by tight junction disruption or epithelial cell death. This technique measures PI-stained extruded dead cells within the organoid lumen to analyze the effect of insults, toxins, or treatments on intestinal organoid permeability.

•

This protocol allows measurement of intestinal permeability in organoids

•

The permeability assay is scalable and reproducible

•

Allows assessment of drugs targeting intestinal epithelial permeability

•

Knockout mouse strains may also be used to dissect pathobiology of permeability

A review of alcohol-pathogen interactions: New insights into combined disease pathomechanisms

Progression of chronic infections to end-stage diseases and poor treatment results are frequently associated with alcohol abuse. Alcohol metabolism suppresses innate and adaptive immunity leading to increased viral load and its spread. In case of hepatotropic infections, viruses accelerate alcohol-induced hepatitis and liver fibrosis, thereby promoting end-stage outcomes, including cirrhosis and hepatocellular carcinoma (HCC). In this review, we concentrate on several unexplored aspects of these phenomena, which illustrate the combined effects of viral/bacterial infections and alcohol in disease development. We review alcohol-induced alterations implicated in immunometabolism as a central mechanism impacting metabolic homeostasis and viral pathogenesis in Simian immunodeficiency virus/human immunodeficiency virus infection. Furthermore, in hepatocytes, both HIV infection and alcohol activate oxidative stress to cause lysosomal dysfunction and leakage and apoptotic cell death, thereby increasing hepatotoxicity. In addition, we discuss the mechanisms of hepatocellular carcinoma and tumor signaling in hepatitis C virus infection. Finally, we analyze studies that review and describe the immune derangements in hepatotropic viral infections focusing on the development of novel targets and strategies to restore effective immunocompetency in alcohol-associated liver disease. In conclusion, alcohol exacerbates the pathogenesis of viral infections, contributing to a chronic course and poor outcomes, but the mechanisms behind these events are virus specific and depend on virus-alcohol interactions, which differ among the various infections.

Inflammation in alcohol-associated liver disease progression

Chronic alcohol consumption induces stress and damage in alcohol metabolising hepatocytes, which leads to inflammatory and fibrogenic responses. Besides these direct effects, alcohol disrupts intestinal barrier functions and induces gut microbial dysbiosis, causing translocation of bacteria or microbial products through the gut mucosa to the liver and, which induce inflammation indirectly. Inflammation is one of the key drivers of alcohol-associated liver disease progression from steatosis to severe alcoholic hepatitis. The current standard of care for the treatment of severe alcoholic hepatitis is prednisolone, aiming to reduce inflammation. Prednisolone, however improves only short-term but not long-term survival rates in those patients, and even increases the risk for bacterial infections. Thus, recent studies focus on the exploration of more specific inflammatory targets for the treatment of severe alcoholic hepatitis. These comprise, among others interference with inflammatory cytokines, modulation of macrophage phenotypes or targeting of immune cell communication, as summarized in the present overview. Although several approaches give promising results in preclinical studies, data robustness and ability to transfer experimental results to human disease is still not sufficient for effective clinical translation.

Human Immunocompetent Model of Neuroendocrine Liver Metastases Recapitulates Patient-Specific Tumour Microenvironment

Neuroendocrine liver metastases (LM-NEN) develop in a considerable proportion of patients with gastroenteropancreatic neuroendocrine neoplasms. There is a paucity of experimental models that accurately recapitulate this complex metastatic human liver microenvironment precluding scientific and clinical advancements. Here, we describe the development of a novel personalised immunocompetent precision cut tumour slice (PCTS) model for LM-NEN using resected human liver tissue. The histological assessment throughout the culture demonstrated that slices maintain viability for at least 7 days and retain the cellular heterogeneity of the original tumour. Essential clinical features, such as patient-specific histoarchitecture, tumour grade, neuroendocrine differentiation and metabolic capacity, are preserved in the slices. The PCTS also replicate the tumor-specific immunological profile as shown by the innate and adaptive immunity markers analysis. Furthermore, the study of soluble immune checkpoint receptors in the culture supernatants proves that these immunomodulators are actively produced by LM-NEN and suggests that this process is epithelium-dependent. This model can be employed to investigate these pathways and provides a powerful platform for mechanistic, immunological and pre-clinical studies.

Epigenetic upregulation of TET2 is an independent poor prognostic factor for intrahepatic cholangiocarcinoma

Mutations in IDH1/2 and the epigenetic silencing of TET2 occur in leukaemia or glioma in a mutually exclusive manner. Although intrahepatic cholangiocarcinoma (iCCA) may harbour IDH1/2 mutations, the contribution of TET2 to carcinogenesis remains unknown. In the present study, the expression and promoter methylation of TET2 were investigated in iCCA. The expression of TET2 was assessed in 52 cases of iCCA (small-duct type, n = 33; large-duct type, n = 19) by quantitative PCR, immunohistochemistry (IHC) and a sequencing-based methylation assay, and its relationships with clinicopathological features and alterations in cancer-related genes (e.g., KRAS and IDH1) were investigated. In contrast to non-neoplastic bile ducts, which were negative for TET2 on IHC, 42 cases (81%) of iCCA showed the nuclear overexpression of TET2. Based on IHC scores (area × intensity), these cases were classified as TET2-high (n = 25) and TET2-low (n = 27). The histological type, tumour size, lymph node metastasis and frequency of mutations in cancer-related genes did not significantly differ between the two groups. Overall and recurrence-free survival were significantly worse in patients with TET2-high iCCA than in those with TET2-low iCCA. A multivariate analysis identified the high expression of TET2 as an independent prognostic factor (HR = 2.94; p = 0.007). The degree of methylation at two promoter CpG sites was significantly less in TET2-high iCCA than in TET2-low iCCA or non-cancer tissue. In conclusion, in contrast to other IDH-related neoplasms, TET2 overexpression is common in iCCA of both subtypes, and its high expression, potentially induced by promoter hypomethylation, is an independent poor prognostic factor.

The Lipopolysaccharide-Sensing Caspase(s)-4/11 Are Activated in Cirrhosis and Are Causally Associated With Progression to Multi-Organ Injury

Background and Aims

The development of multi-organ injury in cirrhosis is associated with increased intestinal permeability, translocation of gut-derived bacterial products [e.g., lipopolysaccharide (LPS)] into the circulation, and increased non-apoptotic hepatocyte cell death. Pyroptosis is a non-apoptotic, lytic form of cell death mediated by the LPS-sensing caspase(s)-4/11 (caspase-4 in humans, caspase-11 in mice), which leads to activation of the effector protein Gasdermin D (GSDMD) and subsequent formation of pores in the plasma membrane. Endoplasmic reticulum (ER) stress, a feature of cirrhosis, has been identified as a factor promoting the activation of caspase-11, thus increasing sensitivity of the cell to LPS-mediated pyroptosis. The aim of this study was to determine the role of bacterial LPS in the activation of hepatic caspase(s)-4/11 and progression of hepatic and extra-hepatic organ injury in cirrhosis.

Materials and Methods

Human liver samples from patients with stable cirrhosis (SC) or acutely decompensated cirrhosis (AD) were analyzed for caspase-4 activation by immunohistochemistry. Wild-type and Casp11^–/– mice underwent CCl₄ treatment by gavage to induce advanced liver fibrosis, and subsequently low-dose injection of LPS to mimic bacterial translocation and induce multi-organ injury. Liver, kidney, and brain function were assessed by plasma ALT/creatinine and brain water respectively. The activity of inflammatory caspases was assessed by fluorometric assay and the occurrence of pyroptosis and overall cell death in liver tissue by GSDMD cleavage and TUNEL assay, respectively. Primary human hepatocytes were cultured according to standard techniques.

Results

Human liver samples demonstrated increased caspase-4 activation in AD cirrhosis. Caspase-4 activation was associated with MELD score and circulating levels of LDH. Wild-type mice treated with CCl₄ developed significant multi-organ injury (increased ALT, creatinine, and brain water) upon LPS injection, and showed increased hepatic GSDMD cleavage compared to mice treated with CCl₄ alone. Primary human hepatocytes could be sensitized to pyroptosis by pre-treatment with the ER-stress inducer tunicamycin and LPS. Casp11^–/– mice treated with CCl₄ + LPS were significantly protected from multi-organ injury compared to wild-type CCl₄ + LPS.

Conclusion

These data demonstrate for the first time a causal relationship between LPS-mediated activation of caspase(s)-4/11 and development of hepatic and extra-hepatic injury in cirrhosis.

The multifactorial mechanisms of bacterial infection in decompensated cirrhosis

Infections, due to a dysfunctional immune response, pose a great risk to patients with decompensated cirrhosis and herald the beginning of the terminal phase of this disease. Infections typically result from breaches in innate immune barriers and inadequate clearance by immune cells. This leads to bacterial and bacterial product translocation to the systemic circulation, which is already primed by ongoing hepatic inflammation in patients with cirrhosis, who are particularly prone to developing organ failure in the presence of an infection. Early identification of bacterial infection, along with the prompt use of appropriate antibiotics, have reduced the mortality associated with certain infections in patients with decompensated cirrhosis. Judicious use of antibiotic therapy remains imperative given the emergence of multidrug-resistant infections in the cirrhotic population. Important research over the last few years has identified molecular targets on immune cells that may enhance their function, and theoretically prevent infections. Clinical trials are ongoing to delineate the beneficial effects of targeted molecules from their off-target effects. Herein, we review the mechanisms that predispose patients with cirrhosis to bacterial infections, the clinical implications of infections and potential targets for the prevention or treatment of infections in this vulnerable population.

Soluble TIM3 and Its Ligands Galectin-9 and CEACAM1 Are in Disequilibrium During Alcohol-Related Liver Disease and Promote Impairment of Anti-bacterial Immunity

Background and Aims

Immunoregulatory checkpoint receptors (CR) contribute to the profound immunoparesis observed in alcohol-related liver disease (ALD) and in vitro neutralization of inhibitory-CRs TIM3/PD1 on anti-bacterial T-cells can rescue innate and adaptive anti-bacterial immunity. Recently described soluble-CR forms can modulate immunity in inflammatory conditions, but the contributions of soluble-TIM3 and soluble-PD1 and other soluble-CRs to immune derangements in ALD remain unclear.

Methods

In Alcoholic Hepatitis (AH; n = 19), alcohol-related cirrhosis (ARC; n = 53) and healthy control (HC; n = 27) subjects, we measured by Luminex technology (i) plasma levels of 16 soluble-CRs, 12 pro/anti-inflammatory cytokines and markers of gut bacterial translocation; (ii) pre-hepatic, post-hepatic and non-hepatic soluble-CR plasma levels in ARC patients undergoing TIPS; (iii) soluble-CRs production from ethanol-treated immunocompetent precision cut human liver slices (PCLS); (iv) whole-blood soluble-CR expression upon bacterial challenge. By FACS, we assessed the relationship between soluble-TIM3 and membrane-TIM3 and rescue of immunity in bacterial-challenged PBMCs.

Results

Soluble-TIM3 was the dominant plasma soluble-CR in ALD vs. HC (p = 0.00002) and multivariate analysis identified it as the main driver of differences between groups. Soluble-CRs were strongly correlated with pro-inflammatory cytokines, gut bacterial translocation markers and clinical indices of disease severity. Ethanol exposure or bacterial challenge did not induce soluble-TIM3 production from PCLS nor from whole-blood. Bacterial challenge prompted membrane-TIM3 hyperexpression on PBMCs from ALD patient's vs. HC (p < 0.002) and was inversely correlated with plasma soluble-TIM3 levels in matched patients. TIM3 ligands soluble-Galectin-9 and soluble-CEACAM1 were elevated in ALD plasma (AH > ARC; p < 0.002). In vitro neutralization of Galectin-9 and soluble-CEACAM1 improved the defective anti-bacterial and anti-inflammatory cytokine production from E. coli-challenged PBMCs in ALD patients.

Conclusions

Alcohol-related liver disease patients exhibit supra-physiological plasma levels of soluble-TIM3, particularly those with greater disease severity. This is also associated with increased levels of soluble TIM3-ligands and membrane-TIM3 expression on immune cells. Soluble-TIM3 can block the TIM3-ligand synapse and improve anti-bacterial immunity; however, the increased levels of soluble TIM3-binding ligands in patients with ALD negate any potential immunostimulatory effects. We believe that anti-TIM3 neutralizing antibodies currently in Phase I clinical trials or soluble-TIM3 should be investigated further for their ability to enhance anti-bacterial immunity. These agents could potentially represent an innovative immune-based supportive approach to rescue anti-bacterial defenses in ALD patients.

Faecal cytokine profiling as a marker of intestinal inflammation in acutely decompensated cirrhosis

BACKGROUND & AIMS

Gut dysbiosis and inflammation perpetuate loss of gut barrier integrity (GBI) and pathological bacterial translocation (BT) in cirrhosis, contributing to infection risk. Little is known about gut inflammation in cirrhosis and how this differs in acute decompensation (AD). We developed a novel approach to characterise intestinal immunopathology by quantifying faecal cytokines (FCs) and GBI markers.

METHODS

Faeces and plasma were obtained from patients with stable cirrhosis (SC; n = 16), AD (n = 47), and healthy controls (HCs; n = 31). A panel of 15 cytokines and GBI markers, including intestinal fatty-acid-binding protein-2 (FABP2), d-lactate, and faecal calprotectin (FCAL), were quantified by electrochemiluminescence/ELISA. Correlations between analytes and clinical metadata with univariate and multivariate analyses were performed.

RESULTS

Faecal (F) IL-1β, interferon gamma, tumour necrosis factor alpha, IL-21, IL-17A/F, and IL-22 were significantly elevated in AD vs. SC (q <0.01). F-IL-23 was significantly elevated in AD vs. HC (p = 0.0007). FABP2/d-lactate were significantly increased in faeces in AD vs. SC and AD vs. HC (p <0.0001) and in plasma (p = 0.0004; p = 0.011). F-FABP2 correlated most strongly with disease severity (Spearman's rho: Child-Pugh 0.466; p <0.0001; model for end-stage liver disease 0.488; p <0.0001). FCAL correlated with plasma IL-21, IL-1β, and IL-17F only and none of the faecal analytes. F-cytokines and F-GBI markers were more accurate than plasma in discriminating AD from SC.

CONCLUSIONS

FC profiling represents an innovative approach to investigating the localised intestinal cytokine micro-environment in cirrhosis. These data reveal that AD is associated with a highly inflamed and permeable gut barrier. FC profiles are very different from the classical innate-like features of systemic inflammation. There is non-specific upregulation of TH1/TH17 effector cytokines and those known to mediate intestinal barrier damage. This prevents mucosal healing in AD and further propagates BT and systemic inflammation.

LAY SUMMARY

The gut barrier is crucial in cirrhosis in preventing infection-causing bacteria that normally live in the gut from accessing the liver and other organs via the bloodstream. Herein, we characterised gut inflammation by measuring different markers in stool samples from patients at different stages of cirrhosis and comparing this to healthy people. These markers, when compared with equivalent markers usually measured in blood, were found to be very different in pattern and absolute levels, suggesting that there is significant gut inflammation in cirrhosis related to different immune system pathways to that seen outside of the gut. This provides new insights into gut-specific immune disturbances that predispose to complications of cirrhosis, and emphasises that a better understanding of the gut-liver axis is necessary to develop better targeted therapies.

Immunomodulatory Role of the Extracellular Matrix Within the Liver Disease Microenvironment

Chronic liver disease when accompanied by underlying fibrosis, is characterized by an accumulation of extracellular matrix (ECM) proteins and chronic inflammation. Although traditionally considered as a passive and largely architectural structure, the ECM is now being recognized as a source of potent damage-associated molecular pattern (DAMP)s with immune-active peptides and domains. In parallel, the ECM anchors a range of cytokines, chemokines and growth factors, all of which are capable of modulating immune responses. A growing body of evidence shows that ECM proteins themselves are capable of modulating immunity either directly via ligation with immune cell receptors including integrins and TLRs, or indirectly through release of immunoactive molecules such as cytokines which are stored within the ECM structure. Notably, ECM deposition and remodeling during injury and fibrosis can result in release or formation of ECM-DAMPs within the tissue, which can promote local inflammatory immune response and chemotactic immune cell recruitment and inflammation. It is well described that the ECM and immune response are interlinked and mutually participate in driving fibrosis, although their precise interactions in the context of chronic liver disease are poorly understood. This review aims to describe the known pro-/anti-inflammatory and fibrogenic properties of ECM proteins and DAMPs, with particular reference to the immunomodulatory properties of the ECM in the context of chronic liver disease. Finally, we discuss the importance of developing novel biotechnological platforms based on decellularized ECM-scaffolds, which provide opportunities to directly explore liver ECM-immune cell interactions in greater detail.

Perturbations in Mitochondrial Dynamics Are Closely Involved in the Progression of Alcoholic Liver Disease

BACKGROUND

Mitochondria play a fundamental role in the pathogenesis of alcoholic liver disease (ALD). The preservation of functional mitochondria during toxic alcohol insults is essential for cell survival and is maintained by key processes known as mitochondrial dynamics, including fragmentation and fusion, which are regulated by mitochondria-shaping proteins (MSP). We have shown mitochondrial dynamics to be distorted by alcohol in cellular and animal models, but the effect in humans remains unknown.

METHODS

Hepatic gene expression of the main MSP involved in the mitochondrial fusion and fragmentation pathways was evaluated in patients with alcoholic hepatitis (AH) by DNA microarray (n = 15) and Reverse Transcription Polymerase Chain Reaction (n = 32). The activation of dynamin-1-like protein (Drp1) was also investigated in mitochondria isolated from liver biopsies of ALD patients (n = 8). The effects of alcohol on mitochondrial dynamics and on MSP protein expression were studied in human precision-cut liver slices (PCLS) exposed for 24 hours to increasing doses of ethanol (EtOH; 50 to 250 mM).

RESULTS

A profound hyperactivation of the fragmentation pathway was observed in AH patients, with a significant increase in the expression of Drp1 and its adapters/receptors. The translocation of Drp1 to the mitochondria was also induced in patients with severe ALD and was affected in the PCLS with short-term exposure to EtOH but only mildly. The fusion pathway was not altered in ALD, and this was confirmed in the PCLS model.

CONCLUSIONS

The present study reveals the role of mitochondrial dynamics in human ALD, confirming our previous observations in animal and cell culture models of ALD. Taken together, we show that alcohol has a significant impact on the fragmentation pathway, and we confirm Drp1 as a potential therapeutic target in severe ALD.

Differential Expression of Immune Inhibitory Checkpoint Signatures on Antiviral and Inflammatory T Cell Populations in Chronic Hepatitis B

Virus-specific T cells are critical in mediating the pathogenesis of hepatitis B virus (HBV) infection. Interferon gamma (IFNγ)-producing T cells are associated with resolution; in contrast, interleukin-17 (IL-17)-producing T cells are linked to exacerbation of liver inflammation and injury. Checkpoint receptors stringently regulate T cell functions, with their expression profiles varying on different T cell subsets. Blockade of checkpoint receptors may be an effective therapeutic strategy for chronic hepatitis B (CHB); however, blockade may also inadvertently exacerbate proinflammatory responses. In this study, we sought to determine the balance of inflammatory and antiviral T cells and determine their inhibitory receptor profile. The frequency of total and HBV antigen-specific Th17 and Tc17 cells was higher in CHB patients compared with healthy controls (HCs). Th17 and Tc17 cells in CHB patients had significantly lower expression of T cell immunoglobulin and mucin domain protein-3 (TIM-3) compared with HCs, with no difference in programmed death-1 (PD-1) or CD244 expression. Conversely, Th1 and Tc1 cells in CHB patients hyperexpressed PD-1 and CD244, while TIM-3 expression was comparable in both cohorts. During CHB, antiviral IFNγ T cells hyperexpress multiple immune inhibitory receptors driving their functional impairment. In contrast, inflammatory Th17/Tc17 cells hypoexpress TIM-3, but not PD-1 or CD244. Checkpoint inhibitors for CHB should target PD-1 or CD244 to allow restoration of IFNγ responses without affecting inflammatory IL-17 production.

Deficient IL-6/Stat3 Signaling, High TLR7, and Type I Interferons in Early Human Alcoholic Liver Disease: A Triad for Liver Damage and Fibrosis

Mechanisms underlying alcohol-induced liver injury and its progression still remain incompletely understood. Animal models can only address some aspects of the pathophysiology that requires studies directly in humans, which are scarce. We assessed liver inflammatory and immune responses at early stages of alcoholic liver disease in a unique cohort of alcohol-dependent patients undergoing a highly standardized alcohol withdrawal program. In active drinkers, quantitative real-time polymerase chain reaction revealed alcohol-induced activation of tumor necrosis factor alpha, interleukin (IL)-1β, and nuclear factor kappa B in liver tissue already at early disease stages. Double immunofluorescence staining indicated that this proinflammatory response was restricted to activated, CD68-positive macrophages. In parallel, down-regulation of IL-6, inhibition of the signal transducer and activator of transcription 3 (Stat3) pathway, as well as blunted cyclin D expression in hepatocytes, reduced proliferation and favored hepatocyte apoptosis. In addition, immunofluorescence and quantitative real-time polymerase chain reaction of liver tissue showed that alcohol also activated the toll-like receptor (TLR) 7-interferon (IFN) axis in hepatocytes, which was confirmed in alcohol-stimulated primary human hepatocytes and precision-cut liver slices in vitro. Activation of the TLR7-IFN axis strongly correlated with liver fibrosis markers and disease progression. Two weeks of abstinence attenuated the inflammatory response but did not allow recovery of the defective Stat3 pathway or effect on fibrosis-associated factors. Conclusion: In humans, inflammation, activation of the TLR7-IFN axis, and inhibition of Stat3-dependent repair mechanisms in early alcoholic liver disease pave the way for fibrosis development and ultimately disease progression.

Dynamin-1-Like Protein Inhibition Drives Megamitochondria Formation as an Adaptive Response in Alcohol-Induced Hepatotoxicity

Despite the growing global burden of alcoholic liver diseases, therapeutic options are limited, and novel targets are urgently needed. Accumulating evidence suggests that mitochondria adapt in response to ethanol and formation of megamitochondria in the livers of patients is recognized as a hallmark of alcoholic liver diseases. The processes involved in ethanol-induced hepatic mitochondrial changes, the impact on mitochondria-shaping proteins, and the significance of megamitochondria formation remain unknown. In this study, we investigated the mitochondrial and cellular response to alcohol in hepatoma cell line VL-17A. The mitochondrial architecture rapidly changed after 3 or 14 days of ethanol exposure with double-pronged presentation of hyperfragmentation and megamitochondria, and cell growth was inhibited. Dynamin-1-like protein (Drp1) was identified as the main mediator driving these mitochondrial alterations, and its genetic inactivation was determined to foster megamitochondria development, preserving the capacity of the cells to grow despite alcohol toxicity. The role of Drp1 in mediating megamitochondria formation in mice with liver-specific inactivation of Drp1 was further confirmed. Finally, when these mice were fed with ethanol, the presentation of hepatic megamitochondria was exacerbated compared with wild type fed with the same diet. Ethanol-induced toxicity was also reduced. Our study demonstrates that megamitochondria formation is mediated by Drp1, and this phenomenon is a beneficial adaptive response during alcohol-induced hepatotoxicity.

Precision-cut liver slices: a versatile tool to advance liver research

Human precision-cut liver slices represent a robust and versatile ex vivo model which retains the complex and multi-cellular histoarchitecture of the hepatic environment. As such, they represent an ideal model to investigate the mechanisms of liver injury and for the identification of novel therapeutic targets. Schematic overview to highlight the utility of precision-cut liver slices as a relevant and versatile ex-vivo model of liver disease. Top panel; Precision cut liver slices (PCLS) exposed to ethanol develop mega-mitochondria, a classical hallmark of Alcoholic Liver Disease (ALD). Right panel; PCLS from liver tumours can be used as a model for liver cancer and can be used to investigate cancer-immune cell interactions by co-culturing with matched immune cells. Bottom panel; Exposure to a mixture of oleic and linoleic acids can simulate Non-Alcoholic Fatty Liver Disease (NAFLD). Left panel; PCLS can be infected with Hepatitis B and C virus and used as a model to study viral infection and replication.

Establishing a successful rat model of duodenal- jejunal bypass: A detailed guide

Gastric bypass surgery, an operation that restricts the stomach and bypasses the duodenum and part of the jejunum, results in major improvement or remission of type 2 diabetes. Duodenual-jejunal bypass was developed by one of the authors (FR) as an experimental, stomach-sparing variant of gastric bypass surgery to investigate weight-independent mechanisms of surgical control of diabetes. Duodenual-jejunal bypass has been shown to improve various aspects of glucose homeostasis in rodents and in humans, thus providing an experimental model for investigating mechanisms of action of surgery and elusive aspects of gastrointestinal physiology. Performing duodenual-jejunal bypass in rodents, however, is associated with a steep learning curve. Here we report our experience with duodenual-jejunal bypass and provide practical tips for successful surgery in rats. Duodenual-jejunal bypass was performed on 50 lean rats as part of a study aimed at investigating the effect of the procedure on the physiologic mechanisms of glucose homeostasis. During the study, we have progressively refined details of anatomic exposure, technical aspects of duodeno-jejunostomy and peri-operative care. We analysed the role of such refinements in improving operative time and post-operative mortality. We found that refinement of exposure methods of the gastro-duodenal junction aimed at minimizing tension on small visceral vasculature, technical aspects of duodeno-jejunal anastomosis and peri-operative management played a major role in improving the survival rate and operative time. Overall, an experimental model of duodenual-jejunal bypass was successfully reproduced. Based on this experience, we describe here what we believe are the most important technical tips to reduce the learning curve for the procedure.

Mucosa-associated invariant T cells link intestinal immunity with antibacterial immune defects in alcoholic liver disease

BACKGROUND/AIMS

Intestinal permeability with systemic distribution of bacterial products are central in the immunopathogenesis of alcoholic liver disease (ALD), yet links with intestinal immunity remain elusive. Mucosa-associated invariant T cells (MAIT) are found in liver, blood and intestinal mucosa and are a key component of antibacterial host defences. Their role in ALD is unknown.

METHODS/DESIGN

We analysed frequency, phenotype, transcriptional regulation and function of blood MAIT cells in severe alcoholic hepatitis (SAH), alcohol-related cirrhosis (ARC) and healthy controls (HC). We also examined direct impact of ethanol, bacterial products from faecal extracts and antigenic hyperstimulation on MAIT cell functionality. Presence of MAIT cells in colon and liver was assessed by quantitative PCR and immunohistochemistry/gene expression respectively.

RESULTS

In ARC and SAH, blood MAIT cells were dramatically depleted, hyperactivated and displayed defective antibacterial cytokine/cytotoxic responses. These correlated with suppression of lineage-specific transcription factors and hyperexpression of homing receptors in the liver with intrahepatic preservation of MAIT cells in ALD. These alterations were stronger in SAH, where surrogate markers of bacterial infection and microbial translocation were higher than ARC. Ethanol exposure in vitro, in vivo alcohol withdrawal and treatment with Escherichia coli had no effect on MAIT cell frequencies, whereas exposure to faecal bacteria/antigens induced functional impairments comparable with blood MAIT cells from ALD and significant MAIT cell depletion, which was not observed in other T cell compartments.

CONCLUSIONS

In ALD, the antibacterial potency of MAIT cells is compromised as a consequence of contact with microbial products and microbiota, suggesting that the 'leaky' gut observed in ALD drives MAIT cell dysfunction and susceptibility to infection in these patients.

Immune checkpoint receptors: homeostatic regulators of immunity

Alcoholic liver disease (ALD) is an escalating global problem accounting for more than 3 million deaths annually. Bacterial infections are diagnosed in 25-47% of hospitalized patients with cirrhosis and represent the most important trigger for acute decompensation, multi-organ failure, septic shock and death. Current guidelines recommend intensive antibiotic therapy, but this has led to the emergence of multi-drug resistant bacteria, which are associated with increased morbidity and mortality rates. As such, there is a pressing need to explore new paradigms for anti-infective therapy and host-directed immunomodulatory therapies are a promising approach. Paradoxically, cirrhotic patients are characterised by heightened immune activity and exacerbated inflammatory processes but are unable to contend with bacterial infection, demonstrating that whilst immune effector cells are primed, their antibacterial effector functions are switched-off, reflecting a skewed homeostatic balance between anti-pathogen immunity and host-induced immunopathology. Preservation of this equilibrium physiologically is maintained by multiple immune-regulatory checkpoints and these feedback receptors serve as pivotal regulators of the host immunity. Checkpoint receptor blockade is proving to be effective at rescuing deranged/exhausted immunity in pre-clinical studies for chronic viral infection and sepsis. This approach has also obtained FDA approval for restoring anti-tumor immunity, with improved response rates and good safety profiles. To date, no clinical studies have investigated checkpoint blockade in ALD, highlighting an area for development of host-targeted immunotherapeutic strategies in ALD, for which there are no current specific treatment options. This review aims at framing current knowledge on immune checkpoints and the possibility of their therapeutic utility in ALD-associated immune dysfunctions.

Peg-Interferon Lambda Treatment Induces Robust Innate and Adaptive Immunity in Chronic Hepatitis B Patients

IFN-lambda (IFNλ) is a member of the type III IFN family and is reported to possess anti-pathogen, anti-cancer, and immunomodulatory properties; however, there are limited data regarding its impact on host immune responses in vivo. We performed longitudinal and comprehensive immunosurveillance to assess the ability of pegylated (peg)-IFNλ to augment antiviral host immunity as part of a clinical trial assessing the efficacy of peg-IFNλ in chronic hepatitis B (CHB) patients. These patients were pretreated with directly acting antiviral therapy (entecavir) for 12 weeks with subsequent addition of peg-IFNλ for up to 32 weeks. In a subgroup of patients, the addition of peg-IFNλ provoked high serum levels of antiviral cytokine IL-18. We also observed the enhancement of natural killer cell polyfunctionality and the recovery of a pan-genotypic HBV-specific CD4⁺ T cells producing IFN-γ with maintenance of HBV-specific CD8⁺ T cell antiviral and cytotoxic activities. It was only in these patients that we observed strong virological control with reductions in both viral replication and HBV antigen levels. Here, we show for the first time that in vivo peg-IFNλ displays significant immunostimulatory properties with improvements in the main effectors mediating anti-HBV immunity. Interestingly, the maintenance in HBV-specific CD8⁺ T cells in the presence of peg-IFNλ is in contrast to previous studies showing that peg-IFNα treatment for CHB results in a detrimental effect on the functionality of this important antiviral T cell compartment.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov NCT01204762.

Increase in circulating Th17 cells during anti-TNF therapy is associated with ultrasonographic improvement of synovitis in rheumatoid arthritis

BACKGROUND

Anti-TNF agents have revolutionised rheumatoid arthritis (RA) treatment; however, a third of patients fail to achieve therapeutic responses. Unexpectedly, studies in murine and human arthritis have indicated that anti-TNF treatment can increase circulating T helper 17 (Th17) cells, but the relationship to treatment response is unclear. To identify immune correlates of anti-TNF treatment response, we conducted a longitudinal study using clinical, ultrasound and T cell assessments.

METHODS

Patients with RA (n = 25) were studied at protocol visits during the initial 12 weeks of anti-TNF treatment. Improvement in the disease activity score of 28 joints (DAS28) >1.2 defined treatment responders (n = 16) and non-responders (n = 9). Changes in synovial thickening and vascularity of 10 metacarpophalangeal joints were quantitatively assessed by grey scale and power Doppler ultrasound. The frequency of circulating Th17 cells was determined by IL17 enzyme-linked immunospot assay (Elispot) and flow cytometry (fluorescence-activated cell sorting (FACS)).

RESULTS

The frequency of circulating IL17-producing cells increased significantly 12 weeks after anti-TNF initiation (Elispot median (range) specific spot forming cells (spSFC)/10⁶ 360 (280-645) vs 632 (367 - 1167), p = 0.003). The increase in CD4 + IL17+ cells at 12 weeks was confirmed by FACS (median (range) %, 0.7 (0.5-0.9) vs 1.05 (0.6-1.3); p = 0.01). The increase in circulating Th17 cells inversely correlated with reduction in synovial vascularity (r = -0.68, p = 0.007) and thickening (r = -0.39; p = 0.04). Higher frequencies of circulating Th17 cells at baseline were associated with poorer anti-TNF treatment response defined by ultrasonographic measures.

CONCLUSIONS

These results demonstrate a link between changes in circulating Th17 cells with resolution of ultrasonographic features of synovial inflammation and vascularity during anti-TNF treatment. The findings may reflect redistribution of Th17 cells from inflamed joints or TNF-driven regulation of Th17 cell production.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01060098 . Registered 29 January 2010.

Osteopontin is a proximal effector of leptin-mediated non-alcoholic steatohepatitis (NASH) fibrosis

INTRODUCTION

Liver fibrosis develops when hepatic stellate cells (HSC) are activated into collagen-producing myofibroblasts. In non-alcoholic steatohepatitis (NASH), the adipokine leptin is upregulated, and promotes liver fibrosis by directly activating HSC via the hedgehog pathway. We reported that hedgehog-regulated osteopontin (OPN) plays a key role in promoting liver fibrosis. Herein, we evaluated if OPN mediates leptin-profibrogenic effects in NASH.

METHODS

Leptin-deficient (ob/ob) and wild-type (WT) mice were fed control or methionine-choline deficient (MCD) diet. Liver tissues were assessed by Sirius-red, OPN and αSMA IHC, and qRT-PCR for fibrogenic genes. In vitro, HSC with stable OPN (or control) knockdown were treated with recombinant (r)leptin and OPN-neutralizing or sham-aptamers. HSC response to OPN loss was assessed by wound healing assay. OPN-aptamers were also added to precision-cut liver slices (PCLS), and administered to MCD-fed WT (leptin-intact) mice to determine if OPN neutralization abrogated fibrogenesis.

RESULTS

MCD-fed WT mice developed NASH-fibrosis, upregulated OPN, and accumulated αSMA+ cells. Conversely, MCD-fed ob/ob mice developed less fibrosis and accumulated fewer αSMA+ and OPN+ cells. In vitro, leptin-treated HSC upregulated OPN, αSMA, collagen 1α1 and TGFβ mRNA by nearly 3-fold, but this effect was blunted by OPN loss. Inhibition of PI3K and transduction of dominant negative-Akt abrogated leptin-mediated OPN induction, while constitutive active-Akt upregulated OPN. Finally, OPN neutralization reduced leptin-mediated fibrogenesis in both PCLS and MCD-fed mice.

CONCLUSION

OPN overexpression in NASH enhances leptin-mediated fibrogenesis via PI3K/Akt. OPN neutralization significantly reduces NASH fibrosis, reinforcing the potential utility of targeting OPN in the treatment of patients with advanced NASH.

PARP14 promotes the Warburg effect in hepatocellular carcinoma by inhibiting JNK1-dependent PKM2 phosphorylation and activation

Most tumour cells use aerobic glycolysis (the Warburg effect) to support anabolic growth and evade apoptosis. Intriguingly, the molecular mechanisms that link the Warburg effect with the suppression of apoptosis are not well understood. In this study, using loss-of-function studies in vitro and in vivo, we show that the anti-apoptotic protein poly(ADP-ribose) polymerase (PARP)14 promotes aerobic glycolysis in human hepatocellular carcinoma (HCC) by maintaining low activity of the pyruvate kinase M2 isoform (PKM2), a key regulator of the Warburg effect. Notably, PARP14 is highly expressed in HCC primary tumours and associated with poor patient prognosis. Mechanistically, PARP14 inhibits the pro-apoptotic kinase JNK1, which results in the activation of PKM2 through phosphorylation of Thr365. Moreover, targeting PARP14 enhances the sensitization of HCC cells to anti-HCC agents. Our findings indicate that the PARP14-JNK1-PKM2 regulatory axis is an important determinant for the Warburg effect in tumour cells and provide a mechanistic link between apoptosis and metabolism.

Osteopontin neutralisation abrogates the liver progenitor cell response and fibrogenesis in mice

BACKGROUND

Chronic liver injury triggers a progenitor cell repair response, and liver fibrosis occurs when repair becomes deregulated. Previously, we reported that reactivation of the hedgehog pathway promotes fibrogenic liver repair. Osteopontin (OPN) is a hedgehog-target, and a cytokine that is highly upregulated in fibrotic tissues, and regulates stem-cell fate. Thus, we hypothesised that OPN may modulate liver progenitor cell response, and thereby, modulate fibrotic outcomes. We further evaluated the impact of OPN-neutralisation on murine liver fibrosis.

METHODS

Liver progenitors (603B and bipotential mouse oval liver) were treated with OPN-neutralising aptamers in the presence or absence of transforming growth factor (TGF)-β, to determine if (and how) OPN modulates liver progenitor function. Effects of OPN-neutralisation (using OPN-aptamers or OPN-neutralising antibodies) on liver progenitor cell response and fibrogenesis were assessed in three models of liver fibrosis (carbon tetrachloride, methionine-choline deficient diet, 3,5,-diethoxycarbonyl-1,4-dihydrocollidine diet) by quantitative real time (qRT) PCR, Sirius-Red staining, hydroxyproline assay, and semiquantitative double-immunohistochemistry. Finally, OPN expression and liver progenitor response were corroborated in liver tissues obtained from patients with chronic liver disease.

RESULTS

OPN is overexpressed by liver progenitors in humans and mice. In cultured progenitors, OPN enhances viability and wound healing by modulating TGF-β signalling. In vivo, OPN-neutralisation attenuates the liver progenitor cell response, reverses epithelial-mesenchymal-transition in Sox9+ cells, and abrogates liver fibrogenesis.

CONCLUSIONS

OPN upregulation during liver injury is a conserved repair response, and influences liver progenitor cell function. OPN-neutralisation abrogates the liver progenitor cell response and fibrogenesis in mouse models of liver fibrosis.

Blockade of PD1 and TIM3 restores innate and adaptive immunity in patients with acute alcoholic hepatitis

BACKGROUND & AIMS

Susceptibility to bacterial infection is a feature of alcohol-related liver disease. Programmed cell death 1 (PD1), the T-cell immunoglobulin and mucin domain-containing protein 3 (TIM3, also known as hepatitis A virus cellular receptor 2), and their respective ligands-CD274 (also known as PD ligand 1 [PDL1]) and galectin-9-are inhibitory receptors that regulate the balance between protective immunity and host immune-mediated damage. However, their sustained hyperexpression promotes immune exhaustion and paralysis. We investigated the role of these immune inhibitory receptors in driving immune impairments in patients with alcoholic liver disease.

METHODS

In a prospective study, we collected blood samples from 20 patients with acute alcoholic hepatitis (AAH), 16 patients with stable advanced alcohol-related cirrhosis, and 12 healthy individuals (controls). Whole blood or peripheral blood mononuclear cells were assessed for expression of PD1, PDL1, TIM3, galectin-9, and Toll-like receptors on subsets of innate and adaptive immune effector cells. We measured antibacterial immune responses to lipopolysaccharide (endotoxin) using ELISpot assays, and used flow cytometry to quantify cytokine production, phagocytosis, and oxidative burst in the presence or absence of blocking antibodies against PD1 or TIM3.

RESULTS

Antibacterial innate and adaptive immune responses were greatly reduced in patients with AAH, compared with controls, and patients with alcohol-related cirrhosis had less severe dysfunctions in innate immune effector cells and preserved functional T-cell responses. Fewer T cells from patients with AAH produced interferon gamma in response to lipopolysaccharide, compared with controls. In addition, patients with AAH had greater numbers of interleukin 10-producing T cells, and reduced levels of neutrophil phagocytosis and oxidative burst in response to Escherichia coli stimulation, compared with controls. T cells from patients with AAH, but not alcohol-related cirrhosis, expressed higher levels of PD1 and PDL1, or TIM3 and galectin-9, than T cells from controls. Antibodies against PD1 and TIM3 restored T-cell production of interferon gamma, reduced the numbers of interleukin 10-producing T cells, and increased neutrophil antimicrobial activities. Circulating levels of endotoxin in plasma from patients with AAH caused over expression of immune inhibitory receptors on T cells via Toll-like receptor 4 binding to CD14(+) monocytes.

CONCLUSIONS

Antibacterial immune responses are impaired in patients with AAH. Lymphocytes from these patients express high levels of immune inhibitory receptors, produce lower levels of interferon gamma, and have increased IL10 production due to chronic endotoxin exposure. These effects can be reversed by blocking PD1 and TIM3, which increase the antimicrobial activities of T cells and neutrophils.

Alisporivir inhibition of hepatocyte cyclophilins reduces HBV replication and hepatitis B surface antigen production

BACKGROUND & AIMS

Cyclophilins are host factors required for hepatitis C virus replication. Cyclophilin inhibitors such as alisporivir have shown strong anti-hepatitis C virus activity in vitro and in clinical studies. However, little is known about whether hepatocyte cyclophilins are involved in the hepatitis B virus (HBV) life cycle. We investigated the effects of 2 cyclophilin inhibitors (alisporivir and NIM811) on HBV replication and hepatitis B surface antigen (HBsAg) production in cell lines.

METHODS

Liver-derived cell lines producing full-length HBV and HBsAg particles, owing to stable (HepG2215) or transient (HuH-7) transfection, or infected with HBV (HepaRG cells; Invitrogen [Carlsbad, CA]), were incubated with alisporivir or NIM811 alone, or alisporivir in combination with a direct antiviral (telbivudine). The roles of individual cyclophilins in drug response was evaluated by small interfering RNA knockdown of cyclophilin (CYP)A, CYPC, or CYPD in HepG2215 cells, or CYPA knockdown in HuH-7 cells. The kinetics of antiviral activity were assessed based on levels of HBV DNA and HBsAg and Southern blot analysis.

RESULTS

In HepG2215, HuH-7, and HepaRG cells, alisporivir reduced intracellular and secreted HBV DNA, in a dose-dependent manner. Knockdown of CYPA, CYPC, or CYPD (reduced by 80%) significantly reduced levels of HBV DNA and secreted HBsAg. Knockdown of CYPA significantly reduced secretion of HBsAg, leading to accumulation of intracellular HBsAg; the addition of alisporivir greatly reduced levels of HBsAg in these cells. The combination of alisporivir and telbivudine had greater antiviral effects than those of telbivudine or alisporivir alone.

CONCLUSIONS

Alisporivir inhibition of cyclophilins in hepatocyte cell lines reduces replication of HBV DNA and HBsAg production and secretion. These effects are potentiated in combination with direct antiviral agents that target HBV-DNA polymerase.

Preferential targeting of disseminated liver tumors using a recombinant adeno-associated viral vector

A novel selectively targeting gene delivery approach has been developed for advanced hepatocellular carcinoma (HCC), a leading cause of cancer mortality whose prognosis remains poor. We combine the strong liver tropism of serotype-8 capsid-pseudotyped adeno-associated viral vectors (AAV8) with a liver-specific promoter (HLP) and microRNA-122a (miR-122a)-mediated posttranscriptional regulation. Systemic administration of our AAV8 construct resulted in preferential transduction of the liver and encouragingly of HCC at heterotopic sites, a finding that could be exploited to target disseminated disease. Tumor selectivity was enhanced by inclusion of miR-122a-binding sequences (ssAAV8-HLP-TK-122aT4) in the expression cassette, resulting in abrogation of transgene expression in normal murine liver but not in HCC. Systemic administration of our tumor-selective vector encoding herpes simplex virus-thymidine kinase (TK) suicide gene resulted in a sevenfold reduction in HCC growth in a syngeneic murine model without toxicity. In summary, we have developed a systemically deliverable gene transfer approach that enables high-level expression of therapeutic genes in HCC but not normal tissues, thus improving the prospects of safe and effective treatment for advanced HCC.

MacroH2A1 isoforms are associated with epigenetic markers for activation of lipogenic genes in fat-induced steatosis

The importance of epigenetic changes in the development of hepatic steatosis is largely unknown. The histone variant macroH2A1 under alternative splicing gives rise to macroH2A1.1 and macroH2A1.2. In this study, we show that the macroH2A1 isoforms play an important role in the regulation of lipid accumulation in hepatocytes. Hepatoma cell line and immortalized human hepatocytes transiently transfected or knocked down with macroH2A1 isoforms were used as in vitro model of fat-induced steatosis. Gene expressions were analyzed by quantitative PCR array and Western blot. Chromatin immunoprecipitation analysis was performed to check the association of histone H3 lysine 27 trimethylation (H3K27me3) and histone H3 lysine 4 trimethylation (H3K4me3) with the promoter of lipogenic genes. Livers from knockout mice that are resistant to lipid deposition despite a high-fat diet were used for histopathology. We found that macroH2A1.2 is regulated by fat uptake and that its overexpression caused an increase in lipid uptake, triglycerides, and lipogenic genes compared with macroH2A1.1. This suggests that macroH2A1.2 is important for lipid uptake, whereas macroH2A1.1 was found to be protective. The result was supported by a high positivity for macroH2A1.1 in knockout mice for genes targeted by macroH2A1 (Atp5a1 and Fam73b), that under a high-fat diet presented minimal lipidosis. Moreover, macroH2A1 isoforms differentially regulate the expression of lipogenic genes by modulating the association of the active (H3K4me3) and repressive (H3K27me3) histone marks on their promoters. This study underlines the importance of the replacement of noncanonical histones in the regulation of genes involved in lipid metabolism in the progression of steatosis.

Truncated CXCL10 is associated with failure to achieve spontaneous clearance of acute hepatitis C infection

The pathogenesis of hepatitis C virus (HCV) infection is strongly influenced by the nature of the host's antiviral immunity. Counterintuitively, elevated serum concentrations of C-X-C chemokine 10 (CXCL10), a potent chemoattractant for antiviral T-cells and NK-cells, are associated with poor treatment outcomes in patients with chronic HCV. It has been reported that an N-terminal truncated form of CXCL10, generated by the protease dipeptidylpeptidase 4 (DPP4), can act as chemokine antagonist. We sought to investigate CXCL10 antagonism in the clinical outcome and evolution of acute HCV infection. We collected serial blood samples from 16 patients, at the clinical onset of acute HCV infection and at 12 standardized follow-up timepoints over the first year. Intact and truncated CXCL10 and DPP4 activity were quantified in all longitudinal samples. In addition, NK-cell frequency/phenotype, and HCV-specific T-cell responses were assessed. Subjects developing chronicity (n = 11) had higher concentrations of CXCL10 (P < 0.001), which was predominantly in a truncated form (P = 0.036) compared to patients who spontaneously resolved infection (n = 5). Truncated CXCL10 correlated with HCV-RNA (r = 0.40, P < 0.001) and DPP4 activity (r = 0.53, P < 0.001). Subjects who resolved infection had a higher frequency of HCV-specific interferon-gamma (IFNγ)-producing T-cells (P = 0.017) and predominance of cytotoxic NK-cells (P = 0.005) compared to patients who became chronic. Patients who became persistently infected had higher proportions of cytokine-producing NK-cells, which were correlated with concentrations of truncated CXCL10 (r = 0.92, P < 0.001).

CONCLUSION

This study provides the first evidence of chemokine antagonism during acute HCV infection. We suggest that the DPP4-CXCL10 axis inhibits antiviral innate and adaptive host immunity and favors establishment of viral persistence.

Identification of serum cytokine profiles associated with HBeAg seroconversion following antiviral treatment interruption

The major shortcoming of nucleos(t)ide analogue therapy for chronic hepatitis B (CHB) is the frequent requirement for indefinite therapy. Withdrawal of treatment can result in viral rebound with an alanine aminotransferase (ALT) flare leading to hepatic decompensation, while in others this can lead to hepatitis B e antigen (HBeAg) seroconversion. The aim of the study was to identify host immune profiles associated with these different outcomes. Eighteen HBeAg(+) patients, enrolled on a phase III trial with the nucleoside analogue adefovir dipivoxil, were followed for up to 128 weeks. For the first 48 weeks, all patients received continuous therapy. Subsequently, patients experienced cycles of treatment interruptions due to random drug/placebo misallocations. Host immune profiles were characterized by measuring a panel of serum cytokines before, during, and after each cycle of treatment withdrawal. Virus-specific T-cell responses were also determined at these time points in a subset of patients to elucidate the mechanisms utilized to control hepatitis B virus (HBV) replication post-treatment. Significantly, elevated levels of IFN-γ, IP-10, and IL-2 on-treatment were associated with HBeAg seroconversion after treatment withdrawal. In these patients, treatment interruption induced further increases in serum IFN-γ levels and marked increases in virus-specific T-cells producing IFN-γ, but minimal alterations in viremia and ALT. In HBeAg(+) patients with low on-treatment levels of serum IFN-γ, the interruption of therapy induced significant elevations in HBV-DNA, ALT, IP-10, and increases in virus-specific T-cells producing IL-10. Evaluating on-treatment serum cytokines in concert with virologic and clinical parameters may help to identify CHB patients who can successfully discontinue nucleos(t)ide analogue therapy.

The diversity and management of chronic hepatitis B virus infections in the United Kingdom: a wake-up call

BACKGROUND

Through migration, diversity of chronic hepatitis B virus (HBV) infection has changed, affecting disease burden and control. We describe clinical and viral characteristics of chronic HBV in the United Kingdom.

METHODS

A total of 698 individuals with chronic HBV infection were recruited from referral liver centers. Demographic, clinical, and laboratory data were collected.

RESULTS

Sixty-one percent of patients were male, 80% were not born in the United Kingdom, and the largest ethnicity was East/Southeast Asian (36%). Twenty-two percent were hepatitis B e antigen (HBeAg) seropositive; 20.4% (59/289) had cirrhosis and 10 (1.7%) had hepatocellular carcinoma. Genotype D was most common (31%) followed by A, C, B, and E (20%, 20%, 19%, and 9%, respectively). Genotype was significantly associated with country of birth, length of time in the United Kingdom, HBeAg status, and precore and basal core promoter mutations. One-third were on treatment, with men independently more likely to be treated. Only 18% of those on treatment were on recommended first-line therapies, and 30% were on lamivudine monotherapy. Among treated individuals, 27% had antiviral drug resistance. Testing rates for human immunodeficiency virus, hepatitis C virus, and delta coinfections were low.

CONCLUSIONS

We demonstrated diversity of chronic HBV infections in UK patients, suggesting that optimal management requires awareness of the variable patterns of chronic HBV in countries of origin. We also found less-than-optimal clinical management practices, possible gender-based treatment bias, and the need to improve testing for coinfections.

Cytokine profiles in high risk injection drug users suggests innate as opposed to adaptive immunity in apparent resistance to hepatitis C virus infection

A cohort of injection drug users (IDU) have been identified who despite a long history of IDU and sharing of injecting equipment remain seronegative and aviraemic for hepatitis C virus (HCV). They have been termed HCV exposed uninfected (EU). The study of potential innate or adaptive immune mechanisms of resistance to HCV infection in this group is of interest. The aim of this study was to determine the levels of a broad range of cytokines in serum of exposed, uninfected individuals to ascertain whether there is a specific cytokine profile associated with apparent resistance to HCV. Sera from 22 EU individuals were analysed for a range of cytokines and chemokines, and compared to 16 treatment-naive chronic HCV cases (HCV Ab+ RNA+), 16 individuals with spontaneous resolution of HCV (HCV-Ab+ and HCV-RNA-) and 10 healthy unexposed controls. EU subjects had strikingly higher levels of both IL-6 (on average more than 100-fold, P = 0.001) and IL-8 (on average more than 10-fold, P < 0.001) than the comparison groups. Additionally higher levels of tumour necrosis factor-alpha (TNF-α; on average up to threefold, P = 0.02) were seen in EU individuals. The levels of interferon-alpha (IFN-α) were upregulated in all HCV exposed groups in comparison to healthy controls (P = 0.013). Adaptive immune cytokine levels were no different between the groups. Cytokine profiling demonstrated raised levels of pro-inflammatory innate immune cytokines and chemokines in EU IDU, in particular interleukin-6 and interleukin-8. These findings suggest innate immune activation may be the key to prevention of infection in this cohort.

P5-13-24: A Predictive Model of Early Systemic Disease Relapse after Standard Adjuvant Therapy for Breast Cancer

Background

Early relapse after adjuvant therapy for breast cancer is very discouraging and remains a major problem. We sought to identify predictors of early relapse risk and build a predictive model for relapse using prospectively collected data for patients seen at the Markey Cancer Center starting 2007 to date.

Methods: Of the 1098 new patients seen, 814 patients had stage I-III disease and were further analyzed for predictors of early relapse risk. Univariate analyses were performed for key variables including patient age, tumor size, grade, estrogen receptor (ER) status, progesterone receptor (PgR) status, and HER2 status. A multivariate Cox regression model was built to identify predictors of systemic relapse and model-building was performed using step-wise model selection to determine candidate models. A risk score was developed based on the linear combination of covariates in the final Cox model. Time-dependent predictive curves, a newly developed statistical methodology, were used to evaluate the predictive accuracy of the proposed risk score.

Results: Median patient age was 57 years (Range 25–92) and 88% were white. Forty six (46) % had stage I disease, 36% stage II, and 18% stage III. Median follow up time was 2.3 years. Of this 814 patient cohort, 708 patients had complete baseline covariate data and were used to build the candidate models. The final Cox regression model included 5 covariates that were significantly associated with risk of early relapse: stage III disease (p = 0.0011), grade III (p = 0.0028), PgR-negative status (p = 0.0121), HER2−negative status (p = 0.0305), and node-positive status (p = 0.0360). These five covariates were then used to calculate an early recurrence risk score, which is the weighted average of these risk factors when present, with the weights being the coefficients from the Cox regression model. The 1-year, 2-year and 3-year predictive curves for this risk score decrease considerably, especially for the 2-year and 3-year curves, indicating good predictive accuracy of the risk score. The highest risk score group, which represents 4.8% of the population, has a 1-year, 2-year and 3-year relapse probabilities of 13.0% (95% CI: 4.1%, 27.3%), 39.4 % (95% CI: 20.1%, 58.3%), and 52.3% (95% CI: 28.5%, 71.5%), respectively. In comparison, for the overall population, the corresponding 1-year, 2-year, and 3-year relapse probabilities were only 1.1% (95% CI: 0.5%, 2.1%), 4.2% (95% CI: 2.7%, 6.1%) and 6.2% (95% CI: 4.2%, 8.6%), respectively.

Conclusions: The developed risk score based on stage, tumor grade, PgR, HER2, and node status is highly predictive of early relapse in breast cancer patients after standard adjuvant therapy. Our model can be used to identify patients with high risk of early disease relapse who may otherwise benefit from enrollment on novel adjuvant therapeutic trials to improve their outcome.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-13-24.

Comparison of low-temperature-sensitive liposome encapsulated docetaxel and doxorubicin in a murine model of prostate cancer

31

Background: Low-temperature-sensitive liposomes (LTSLs) release their encapsulated drug into targeted tissue when activated by a source of hyperthermia. The efficacy of an LTSL formulation of docetaxel (DOC) or doxorubicin (DOX) was compared against prostate cancer in a xenograft mouse model.

Methods: Under an approved IACUC protocol, Luciferase transfected human prostate PC-3M-luciferase cells were inoculated (3x106 cells) subcutaneously in the right hind leg of 8 wk old female athymic nude mice. When tumors reached a volume of 200–300 mm3, mice were randomized to receive one intravenous injection of saline, Stealth liposomal DOX (5 mg/kg), LTSL DOX (5 mg/kg), or LTSL DOC (15 mg/kg), with or without hyperthermia treatment (LTSL DOX and LTSL DOC were supplied by Celsion Corp., Columbia MD). Mice undergoing hyperthermia treatment were anesthetized and stabilized in a holder that allowed for only the leg with tumor to be heated to 41–42°C that triggered LTSL drug release. Mice were monitored daily for tumor volume and body weight. Study end-points included growth of tumor to 5x the initial treatment volume or monitoring of survival for 60 days.

Results: The LTSL DOC delayed tumor growth longer (> 14 days) than DOX (0 day) and LTSL DOX (1 day) with hyperthermia (P<0.05). Mice treated with LTSL DOC and hyperthermia survived longest (60 days) compared to all other mice (range 6–8 days, P<0.05). LTSL in the setting of hyperthermia demonstrated complete regression of tumor in 57% of mice.

Conclusions: LTSL DOC with hyperthermia delayed tumor growth more than all other treatments. Survival studies suggest LTSL DOC is a more effective temperature sensitive delivery system against PC-3M prostate tumors.

No significant financial relationships to disclose.