Plasma biomarkers of liver injury and inflammation demonstrate a lack of apoptosis during obstructive cholestasis in mice

Validation of NBD-coupled taurocholic acid for intravital analysis of bile acid transport in liver and kidney of mice

Fluorophore-coupled bile acids (BA) represent an important tool for intravital analysis of BA flux in animal models of cholestatic diseases. However, addition of a fluorophore to a BA may alter transport properties. We developed and validated a 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole-coupled taurocholic acid (3β-NBD-TCA) as a probe for intravital analysis of BA homeostasis. We compared transport of 3β-NBD-TCA to [3H]-TCA in HEK293 cells stably expressing the mouse hepatic or renal BA carriers mNtcp or mAsbt, respectively. We also studied distribution kinetics intravitally in livers and kidneys of anesthetized wildtype and mOatp1a/1b cluster knockout mice (OatpKO) with and without administration of the Ntcp inhibitor Myrcludex B and the ASBT inhibitor AS0369. In vitro, 3β-NBD-TCA and [3H]-TCA showed comparable concentration- and time-dependent transport via mNtcp and mAsbt as well as similar inhibition kinetics for Myrcludex B and AS0369. Intravital analysis in the livers of wildtype and OatpKO mice revealed contribution of both mNtcp and mOatp1a/1b in the 3β-NBD-TCA uptake from the sinusoidal blood into hepatocytes. Combined deletion of mOatp1a/1b and inhibition of mNtcp by Myrcludex B blocked the uptake of 3β-NBD-TCA from sinusoidal blood into hepatocytes. This led to an increase of 3β-NBD-TCA signal in the systemic circulation including renal capillaries, followed by strong enrichment in a subpopulation of proximal renal tubular epithelial cells (TEC). The enrichment of 3β-NBD-TCA in TEC was strongly reduced by the systemic ASBT inhibitor AS0369. NBD-coupled TCA has similar transport kinetics as [3H]-TCA and can be used as a tool to study hepatorenal BA transport. See also the graphical abstract(Fig. 1).

Gpbar-1/cAMP/PKA signaling mitigates macrophage-mediated acute cholestatic liver injury via antagonizing NLRP3-ASC inflammasome

Acute cholestatic liver injury (ACLI) is a disease associated with bile duct obstruction that causes liver inflammation and apoptosis. Although G protein-coupled bile acid receptor1 (Gpbar-1) has diverse metabolic roles, its involvement in ACLI-associated immune activation remains unclear. Liver tissues and blood samples from 20 patients with ACLI and 20 healthy individuals were analyzed using biochemical tests, H&E staining, western blotting, and immunohistochemistry to verify liver damage and expression of Gpbar-1. The expression of Gpbar-1, cAMP/PKA signaling, and the NLRP3 inflammasome was tested in wild-type (WT) and Gpbar-1 knockdown (si-Gpbar-1) mice with ACLI induced by bile duct ligation (BDL) and in primary Kupffer cells (KCs) with or without Gpbar-1-siRNA. The results showed that total bile acids and Gpbar-1 expressions were elevated in patients with ACLI. Gpbar-1 knockdown significantly worsened BDL-induced acute hepatic damage, inflammation, and liver apoptosis in vivo. Knockdown of Gpbar-1 heightened KC sensitivity to lipopolysaccharide (LPS) stimulation. Gpbar-1 activation inhibited LPS-induced pro-inflammatory responses in normal KCs but not in Gpbar-1-knockdown KCs. Notably, NLRP3-ASC inflammasome expression was effectively enhanced by Gpbar-1 deficiency. Additionally, Gpbar-1 directly increased intracellular cAMP levels and PKA phosphorylation, thus disrupting the NLRP3-ASC inflammasome. The pro-inflammatory characteristic of Gpbar-1 deficiency was almost neutralized by the NLRP3 inhibitor CY-09. In vitro, M1 polarization was accelerated in LPS-stimulated Gpbar-1-knockdown KCs. Therapeutically, Gpbar-1 deficiency exacerbated BDL-induced ACLI, which could be rescued by inhibition of the NLRP3-ASC inflammasome. Our study reveal that Gpbar-1 may act as a novel immune-mediated regulator of ACLI by inhibiting the NLRP3-ASC inflammasome.

The Role of miRNA and Long Noncoding RNA in Cholestatic Liver Diseases

Cholestatic liver diseases encompass a range of organic damages, metabolic disorders, and dysfunctions within the hepatobiliary system, arising from various pathogenic causes. These factors contribute to disruptions in bile production, secretion, and excretion. Cholestatic liver diseases can be classified into intrahepatic and extrahepatic cholestasis, according to the location of occurrence. The etiology of cholestatic liver diseases is complex, and includes drugs, poisons, viruses, parasites, bacteria, autoimmune responses, tumors, and genetic metabolism. The pathogenesis of cholelstatic liver disease is not completely clarified, and effective therapy is lacking. Clarifying its mechanism to find more effective therapeutic targets and drugs is an unmet need. Increasing evidence demonstrates that miRNA and long noncoding RNA are involved in the progression of cholestatic liver diseases. This review provides a comprehensive summary of the research progress on the roles of miRNA and long noncoding RNA in cholestatic liver diseases. The aim of the review is to enhance the understanding of their potential diagnostic, therapeutic, and prognostic value for patients with cholestasis.

Pregnane X receptor as a therapeutic target for cholestatic liver injury

Cholestatic liver injury (CLI) is caused by toxic bile acids (BAs) accumulation in the liver and can lead to inflammation and liver fibrosis. The mechanisms underlying CLI development remain unclear, and this disease has no effective cure. However, regulating BA synthesis and homeostasis represents a promising therapeutic strategy for CLI treatment. Pregnane X receptor (PXR) plays an essential role in the metabolism of endobiotics and xenobiotics via the transcription of metabolic enzymes and transporters, which can ultimately modulate BA homeostasis and exert anticholestatic effects. Furthermore, recent studies have demonstrated that PXR exhibits antifibrotic and anti-inflammatory properties, providing novel insights into treating CLI. Meanwhile, several drugs have been identified as PXR agonists that improve CLI. Nevertheless, the precise role of PXR in CLI still needs to be fully understood. This review summarizes how PXR improves CLI by ameliorating cholestasis, inhibiting inflammation, and reducing fibrosis and discusses the progress of promising PXR agonists for treating CLI.

The Role of Inflammation in Cholestatic Liver Injury

Cholestasis is a common clinical event in which bile formation and excretion are blocked, leading to retention of bile acids or bile salts; whether it occurs intra- or extrahepatically, primary or secondary, its pathogenesis is still unclear and is influenced by a combination of factors. In a variety of inflammatory and immune cells such as neutrophils, macrophages (intrahepatic macrophages are also known as Kupffer cells), mast cells, NK cells, and even T cells in humoral immunity and B cells in cellular immunity, inflammation can be a "second strike" against cholestatic liver injury. These cells, stimulated by a variety of factors such as bile acids, inflammatory chemokines, and complement, can be activated and accumulate in the cholestatic liver, and with the involvement of inflammatory mediators and modulation by cytokines, can lead to destruction of hepatocytes and bile duct epithelial cells and exacerbate (and occasionally retard) the progression of cholestatic liver disease. In this paper, we summarized the new research advances proposed so far regarding the relationship between inflammation and cholestasis, aiming to provide reference for researchers and clinicians in the field of cholestatic liver injury research.

Implications of gut microbiota in autoimmune liver diseases

Autoimmune liver diseases (AILD) are a group of immune-mediated liver inflammatory diseases with three major forms including autoimmune hepatitis (AIH), primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC). Interaction of both genetic and environmental factors leads to the breakdown of self-tolerance, hence resulting in hyper-responsive of autoantibodies and aggressive autoreactive immune cells. Genetic studies have identified dozens of risk loci associated with initiation and development of AILD. However, the role of exogenous factors remains unclear. Recently, both infectious and inflammatory diseases have been associated with microbiota, which colonizes multiple mucosal surfaces and participates in human physiological process and function in immune system, particularly influencing liver, and biliary system via gut-liver axis. Emerging evidence on the role of gut microbiota has expanded our knowledge of AILD in both pathogenesis and potential therapeutic targets, along with putative diagnosis biomarkers. Herein we review the relationship between host and gut microbiota, discuss their potential roles in disease onset and progression, and summarize the compositional and functional alterations of the microbiota in AILD. We also highlighted the microbiota-based therapeutics such as antibiotics and fecal microbiota transplantation (FMT).

Hepatic ribosomal protein S6 (Rps6) insufficiency results in failed bile duct development and loss of hepatocyte viability; a ribosomopathy-like phenotype that is partially p53-dependent

Defective ribosome biogenesis (RiBi) underlies a group of clinically diverse human diseases collectively known as the ribosomopathies, core manifestations of which include cytopenias and developmental abnormalities that are believed to stem primarily from an inability to synthesize adequate numbers of ribosomes and concomitant activation of p53. The importance of a correctly functioning RiBi machinery for maintaining tissue homeostasis is illustrated by the observation that, despite having a paucity of certain cell types in early life, ribosomopathy patients have an increased risk for developing cancer later in life. This suggests that hypoproliferative states trigger adaptive responses that can, over time, become maladaptive and inadvertently drive unchecked hyperproliferation and predispose to cancer. Here we describe an experimentally induced ribosomopathy in the mouse and show that a normal level of hepatic ribosomal protein S6 (Rps6) is required for proper bile duct development and preservation of hepatocyte viability and that its insufficiency later promotes overgrowth and predisposes to liver cancer which is accelerated in the absence of the tumor-suppressor PTEN. We also show that the overexpression of c-Myc in the liver ameliorates, while expression of a mutant hyperstable form of p53 partially recapitulates specific aspects of the hepatopathies induced by Rps6 deletion. Surprisingly, co-deletion of p53 in the Rps6-deficient background fails to restore biliary development or significantly improve hepatic function. This study not only reveals a previously unappreciated dependence of the developing liver on adequate levels of Rps6 and exquisitely controlled p53 signaling, but suggests that the increased cancer risk in ribosomopathy patients may, in part, stem from an inability to preserve normal tissue homeostasis in the face of chronic injury and regeneration.

PPARα: A potential therapeutic target of cholestasis

The accumulation of bile acids in the liver leads to the development of cholestasis and hepatocyte injury. Nuclear receptors control the synthesis and transport of bile acids in the liver. Among them, the farnesoid X receptor (FXR) is the most common receptor studied in treating cholestasis. The activation of this receptor can reduce the amount of bile acid synthesis and decrease the bile acid content in the liver, alleviating cholestasis. Ursodeoxycholic acid (UDCA) and obeticholic acid (OCA) have a FXR excitatory effect, but the unresponsiveness of some patients and the side effect of pruritus seriously affect the results of UDCA or OCA treatment. The activator of peroxisome proliferator-activated receptor alpha (PPARα) has emerged as a new target for controlling the synthesis and transport of bile acids during cholestasis. Moreover, the anti-inflammatory effect of PPARα can effectively reduce cholestatic liver injury, thereby improving patients’ physiological status. Here, we will focus on the function of PPARα and its involvement in the regulation of bile acid transport and metabolism. In addition, the anti-inflammatory effects of PPARα will be discussed in some detail. Finally, we will discuss the application of PPARα agonists for cholestatic liver disorders.

Interruption of bile acid uptake by hepatocytes after acetaminophen overdose ameliorates hepatotoxicity

BACKGROUND & AIMS

Acetaminophen (APAP) overdose remains a frequent cause of acute liver failure, which is generally accompanied by increased levels of serum bile acids (BAs). However, the pathophysiological role of BAs remains elusive. Herein, we investigated the role of BAs in APAP-induced hepatotoxicity.

METHODS

We performed intravital imaging to investigate BA transport in mice, quantified endogenous BA concentrations in the serum of mice and patients with APAP overdose, analyzed liver tissue and bile by mass spectrometry and MALDI-mass spectrometry imaging, assessed the integrity of the blood-bile barrier and the role of oxidative stress by immunostaining of tight junction proteins and intravital imaging of fluorescent markers, identified the intracellular cytotoxic concentrations of BAs, and performed interventions to block BA uptake from blood into hepatocytes.

RESULTS

Prior to the onset of cell death, APAP overdose causes massive oxidative stress in the pericentral lobular zone, which coincided with a breach of the blood-bile barrier. Consequently, BAs leak from the bile canaliculi into the sinusoidal blood, which is then followed by their uptake into hepatocytes via the basolateral membrane, their secretion into canaliculi and repeated cycling. This, what we termed 'futile cycling' of BAs, led to increased intracellular BA concentrations that were high enough to cause hepatocyte death. Importantly, however, the interruption of BA re-uptake by pharmacological NTCP blockage using Myrcludex B and Oatp knockout strongly reduced APAP-induced hepatotoxicity.

CONCLUSIONS

APAP overdose induces a breach of the blood-bile barrier which leads to futile BA cycling that causes hepatocyte death. Prevention of BA cycling may represent a therapeutic option after APAP intoxication.

LAY SUMMARY

Only one drug, N-acetylcysteine, is approved for the treatment of acetaminophen overdose and it is only effective when given within ∼8 hours after ingestion. We identified a mechanism by which acetaminophen overdose causes an increase in bile acid concentrations (to above toxic thresholds) in hepatocytes. Blocking this mechanism prevented acetaminophen-induced hepatotoxicity in mice and evidence from patients suggests that this therapy may be effective for longer periods after ingestion compared to N-acetylcysteine.

Redundant Functions of ERK1 and ERK2 Maintain Mouse Liver Homeostasis Through Down-Regulation of Bile Acid Synthesis

Activation of extracellular signal-regulated kinase (ERK) 1/2 promotes hepatocyte proliferation in response to growth stimuli, but whether constitutive hepatocyte ERK1/2 signaling functions in liver physiology is unknown. To examine the role of ERK1/2 in hepatic homeostasis, the effects of a knockout of Erk1 and/or Erk2 in mouse liver were examined. The livers of mice with a global Erk1 knockout or a tamoxifen-inducible, hepatocyte-specific Erk2 knockout were normal. In contrast, Erk1/2 double-knockout mice developed hepatomegaly and hepatitis by serum transaminases, histology, terminal deoxynucleotide transferase-mediated deoxyuridine triphosphate nick end-labeling, and assays of hepatic inflammation. Liver injury was associated with biochemical evidence of cholestasis with increased serum and hepatic bile acids and led to hepatic fibrosis and mortality. RNA sequencing and polymerase chain reaction analysis of double-knockout mouse livers revealed that the rate-limiting bile acid synthesis gene Cyp7a1 (cholesterol 7α-hydroxylase) was up-regulated in concert with decreased expression of the transcriptional repressor short heterodimer partner. Elevated bile acids were the mechanism of liver injury, as bile acid reduction by SC-435, an inhibitor of the ileal apical sodium-dependent bile acid transporter, prevented liver injury. Conclusion: Constitutive ERK1 and ERK2 signaling has a redundant but critical physiological function in the down-regulation of hepatic bile acid synthesis to maintain normal liver homeostasis.

Bicyclol Alleviates Signs of BDL-Induced Cholestasis by Regulating Bile Acids and Autophagy-Mediated HMGB1/p62/Nrf2 Pathway

Cholestasis is a liver disease characterized by the accumulation of toxic bile salts, bilirubin, and cholesterol, resulting in hepatocellular damage. Recent findings have revealed several key steps of cholestasis liver injury including the toxicity of bile acids and accumulation of proinflammatory mediator. In this study, we investigated the protective effect of bicyclol in cholestasis caused by bile duct ligation (BDL), as well as relevant mechanisms. Bicyclol attenuated liver damage in BDL mice by increasing the levels of hydrophilic bile acid such as α-MCA and β-MCA, regulating bile acid-related pathways and improving histopathological indexes. High-mobility group box 1 (HMGB1) is an extracellular damage-associated molecular pattern molecule which can be used as biomarkers of cells and host defense. Bicyclol treatment decreased extracellular release of HMGB1. In addition, HMGB1 is also involved in regulating autophagy in response to oxidative stress. Bicyclol promoted the lipidation of LC3 (microtubule-associated protein 1 light chain 3)-Ⅱ to activate autophagy. The nuclear factor, E2-related factor 2 (Nrf2) and its antioxidant downstream genes were also activated. Our results indicate that bicyclol is a promising therapeutic strategy for cholestasis by regulating the bile acids and autophagy-mediated HMGB1/p62/Nrf2 pathway.

Bidirectional Role of NLRP3 During Acute and Chronic Cholestatic Liver Injury

BACKGROUND AND AIMS

Cholestatic liver injury leads to cell death and subsequent inflammation and fibrosis. As shown for primary biliary cholangitis (PBC), the mechanisms and circuits between different cell death pathways leading to disease progression are incompletely defined. Common bile duct ligation (BDL) is a well-established murine model to mimic cholestatic liver injury. Here, we hypothesized that pyroptotic cell death by the Nucleotide-Binding Domain, Leucine-Rich-Containing Family, Pyrin Domain-Containing-3 (Nlrp3) inflammasome plays an essential role during human and murine cholestasis.

APPROACH AND RESULTS

NLRP3 activation was analyzed in humans with cholestatic liver injury. Wild-type (WT) and Nlrp3^-/- mice were subjected to BDL for 2 or 28 days. Chronic cholestasis in humans and mice is associated with NLRP3 activation and correlates with disease activity. Acute BDL in Nlrp3-deficient mice triggered increased inflammation as well as liver injury, associated with stronger apoptotic and necroptotic cell death. In contrast, NLRP3 deletion led to decreased liver injury and inflammation in chronic cholestasis. Moreover, bridging fibrosis was observed in WT, but not in NLRP3 knockout, mice 28 days after BDL. In contrast, lack of NLRP3 expression attenuated kidney injury and fibrosis after acute and chronic BDL. Importantly, administration of MCC950, an NLRP3 small molecule inhibitor, reduced BDL-induced disease progression in WT mice.

CONCLUSIONS

NLRP3 activation correlates with disease activity in patients with PBC. NLRP3 has a differential role during acute and chronic cholestatic liver injury in contrast to kidney injury. Disease progression during chronic cholestasis can be targeted through small molecules and thus suggests a potential clinical benefit for humans, attenuating liver and kidney injury.

miRNA-338-3p/CAMK IIα signaling pathway prevents acetaminophen-induced acute liver inflammation in vivo

INTRODUCTION AND OBJECTIVES

N-acetyl-p-aminophenol (APAP)-induced liver injury is a major clinical challenge worldwide. The present study investigated the molecular role of microRNA (miR)-338-3p in the development of APAP-induced acute liver injury.

MATERIALS AND METHODS

B6 mice were treated with an miR-338-3p agomir, antagomir, and intraperitoneally injected with APAP 24h later to induce acute liver injury. Histological analysis was performed to evaluate the degree of liver injury. The gene expression of miR-338-3p and its downstream regulators was measured by reverse transcription-quantitative PCR and western blot. The miR target was validated using a luciferase reporter assay.

RESULTS

The results revealed that miR-338-3p was significantly upregulated following the intraperitoneal administration of APAP. Augmenting miR-338-3p alleviated acute liver injury caused by APAP overdose, while silencing of miR-338-3p exhibited a detrimental effect. Moreover, miR-338-3p inhibited the expression of pro-inflammatory cytokines by preventing the aberrant activation of inflammatory signaling pathways, including the nuclear factor kappa-B (NF-κB)/mitogen-activated protein kinase (MAPK) signaling pathway. Furthermore, calcium/calmodulin-dependent protein kinase IIα (CAMK IIα) was identified as a direct target of miR-338-3p.

CONCLUSION

The present study demonstrated that miR-338-3p inhibited inflammation in APAP-induced acute liver injury.

Identification of Serum Biomarkers to Distinguish Hazardous and Benign Aminotransferase Elevations

The standard circulating biomarker of liver injury in both clinical settings and drug safety testing is alanine aminotransferase (ALT). However, ALT elevations sometimes lack specificity for tissue damage. To identify novel serum biomarkers with greater specificity for injury, we combined unique animal models with untargeted proteomics, followed by confirmation with immunoblotting. Using proteomics, we identified 109 proteins in serum from mice with acetaminophen (APAP)-induced liver injury that were not detectable in serum from mice with benign ALT elevations due to high-dose dexamethasone (Dex). We selected 4 (alcohol dehydrogenase 1A1 [Aldh1a1], aldehyde dehydrogenase 1 [Adh1], argininosuccinate synthetase 1 [Ass1], and adenosylhomocysteinase [Ahcy]) with high levels for further evaluation. Importantly, all 4 were specific for injury when using immunoblots to compare serum from Dex-treated mice and mice with similar lower ALT elevations due to milder models of APAP or bromobenzene-induced liver injury. Immunoblotting for ALDH1A1, ADH1, and ASS1 in serum from APAP overdose patients without liver injury and APAP overdose patients with mild liver injury revealed that these candidate biomarkers can be detected in humans with moderate liver injury as well. Interestingly, further experiments with serum from rats with bile duct ligation-induced liver disease indicated that Aldh1a1 and Adh1 are not detectable in serum in cholestasis and may therefore be specific for hepatocellular injury and possibly even drug-induced liver injury, in particular. Overall, our results strongly indicate that ALDH1A1, ADH1, and ASS1 are promising specific biomarkers for liver injury. Adoption of these biomarkers could improve preapproval drug safety assessment.

Cholestasis Differentially Affects Liver Connexins

Connexins are goal keepers of tissue homeostasis, including in the liver. As a result, they are frequently involved in disease. The current study was set up to investigate the effects of cholestatic disease on the production of connexin26, connexin32 and connexin43 in the liver. For this purpose, bile duct ligation, a well-known trigger of cholestatic liver injury, was applied to mice. In parallel, human hepatoma HepaRG cell cultures were exposed to cholestatic drugs and bile acids. Samples from both the in vivo and in vitro settings were subsequently subjected to assessment of mRNA and protein quantities as well as to in situ immunostaining. While the outcome of cholestasis on connexin26 and connexin43 varied among experimental settings, a more generalized repressing effect was seen for connexin32. This has also been observed in many other liver pathologies and could suggest a role for connexin32 as a robust biomarker of liver disease and toxicity.

Inflammation: Cause or consequence of chronic cholestatic liver injury

Cholestasis is a result of obstruction of the biliary tracts. It is a common cause of liver pathology after exposure to toxic xenobiotics and during numerous other liver diseases. Accumulation of bile acids in the liver is thought to be a major driver of liver injury during cholestasis and can lead to eventual liver fibrosis and cirrhosis. As such, current therapy in the field of chronic liver diseases with prominent cholestasis relies heavily on increasing choleresis to limit accumulation of bile acids. Many of these same diseases also present with autoimmunity before the onset of cholestasis though, indicating the inflammation may be an initiating component of the pathology. Moreover, cytotoxic inflammatory mediators accumulate during cholestasis and can propagate liver injury. Anti-inflammatory biologics and small molecules have largely failed clinical trials in these diseases though and as such, targeting inflammation as a means to address cholestatic liver injury remains debatable. The purpose of this review is to understand the different roles that inflammation can play during cholestatic liver injury and attempt to define how new therapeutic targets that limit or control inflammation may be beneficial for patients with chronic cholestatic liver disease.

Inflammation and Cell Death During Cholestasis: The Evolving Role of Bile Acids

Cholestasis results in blockage of bile flow whether the point of obstruction occurs extrahepatically or intrahepatically. Bile acids are a primary constituent of bile, and thus one of the primary outcomes is acute retention of bile acids in hepatocytes. Bile acids are normally secreted into the biliary tracts and then released into the small bowel before recirculating back to the liver. Retention of bile acids has long been hypothesized to be a primary cause of the associated liver injury that occurs during acute or chronic cholestasis. Despite this, a surge of papers in the last decade have reported a primary role for inflammation in the pathophysiology of cholestatic liver injury. Furthermore, it has increasingly been recognized that both the constituency of individual bile acids that make up the greater pool, as well as their conjugation status, is intimately involved in their toxicity, and this varies between species. Finally, the role of bile acids in drug-induced cholestatic liver injury remains an area of increasing interest. The purpose of this review is to critically evaluate current proposed mechanisms of cholestatic liver injury, with a focus on the evolving role of bile acids in cell death and inflammation.

Comparative effectiveness of common therapies for Wilson disease: A systematic review and meta-analysis of controlled studies

BACKGROUND & AIMS

Wilson disease (WD) is a rare disorder of copper metabolism. The objective of this systematic review was to determine the comparative effectiveness and safety of common treatments of WD.

METHODS

We included WD patients of any age or stage and the study drugs D-penicillamine, zinc salts, trientine and tetrathiomolybdate. The control could be placebo, no treatment or any other treatment. We included prospective, retrospective, randomized and non-randomized studies. We searched Medline and Embase via Ovid, the Cochrane Central Register of Controlled Trials, and screened reference lists of included articles. Where possible, we applied random-effects meta-analyses.

RESULTS

The 23 included studies reported on 2055 patients and mostly compared D-penicillamine to no treatment, zinc, trientine or succimer. One study compared tetrathiomolybdate and trientine. Post-decoppering maintenance therapy was addressed in one study only. Eleven of 23 studies were of low quality. When compared to no treatment, D-penicillamine was associated with a lower mortality (odds ratio 0.013; 95% CI 0.0010 to 0.17). When compared to zinc, there was no association with mortality (odds ratio 0.73; 95% CI 0.16 to 3.40) and prevention or amelioration of clinical symptoms (odds ratio 0.84; 95% CI 0.48 to 1.48). Conversely, D-penicillamine may have a greater impact on side effects and treatment discontinuations than zinc.

CONCLUSIONS

There are some indications that zinc is safer than D-penicillamine therapy while being similarly effective in preventing or reducing hepatic or neurological WD symptoms. Study quality was low warranting cautious interpretation of our findings.

Necroptosis signaling in liver diseases: An update

The apoptosis alternate cell death pathways are extensively studied in recent years and their significance has been well recognized. With identification of newer cell death pathways, the therapeutic opportunities to modulate cell death have indeed further extended. Necroptosis, among other apoptosis alternate pathways, has been immensely studied recently in different hepatic disease models. Receptor-interacting protein 1 (RIPK1), RIPK3 and mixed lineage kinase domain like (MLKL) seemed to be the key players to mediate necroptosis pathway. Initially, necroptosis seemed to be following the typical pathway. But recently diverse pathways and outcomes have been observed. With recent studies reporting diverse outcomes, the necroptosis signalling has become a lot more interesting and intricate. The typical RIPK1 signalling followed by RIPK3 and MLKL might not always be strictly followed. Although, necroptosis signalling has been intensively investigated in various disease conditions; however, there is still a need to further elaborate and understand the unique scaffolding and kinase properties and other signalling interactions of necroptosis signalling molecules.

Bile salts regulate CYP7A1 expression and elicit a fibrotic response and abnormal lipid production in 3D liver microtissues

Disrupted regulation and accumulation of bile salts (BS) in the liver can contribute towards progressive liver damage and fibrosis. Here, we investigated the role of BS in the progression of cholestatic injury and liver fibrosis using 3D scaffold-free multicellular human liver microtissues (MTs) comprising the cell lines HepaRG, THP-1 and hTERT-HSCs. This in vitro model has been shown to recapitulate cellular events leading to fibrosis including hepatocellular injury, inflammation and activation of HSCs, ultimately leading to increased deposition of extracellular matrix (ECM). In order to better differentiate the contribution of individual cells during cholestasis, the effects of BS were evaluated either on each of the three cell types individually or on the multicellular MTs. Our data corroborate the toxic effects of BS on HepaRG cells and indicate that BS exposure elicited a slight increase in cytokines without causing stellate cell activation. Contrarily, using the MTs, we could demonstrate that low concentrations of BS led to cellular damage and triggered a fibrotic response. This indicates that cellular interplay is required to achieve BS-triggered activation of HSC. Moreover, BS were capable of down-regulating CYP7A1 expression in MTs and elicited abnormal lipid production (accumulation) concordant with clinical cases where chronic cholestasis results in hypercholesterolemia.

Salvianolic acid B protects against ANIT-induced cholestatic liver injury through regulating bile acid transporters and enzymes, and NF-κB/IκB and MAPK pathways

The purpose of this study was to investigate the pharmacological effects of salvianolic acid B (SA-B) on α-naphthylisothiocyanate (ANIT)-induced cholestatic liver injury with the focus on bile acid homeostasis and anti-inflammatory pathways. Rats were randomly assigned into four groups. The control group was given normal saline (i.p.) for 7 consecutive days and on the 5th day was given the vehicle (i.g.). Model group was treated with normal saline (i.p.) for 7 days and administrated with ANIT (75 mg/kg, i.g.) on the 5th day. The SA-B groups were treated with SA-B (15 mg/kg and 30 mg/kg, i.p.) for 7 consecutive days as well as ANIT (75 mg/kg, i.g.) on the 5th day. We found that the serum levels of ALT, γ-GT, TBA, and other liver function indexes were found to be lower in the SA-B treatment groups than in the model group. SA-B also upregulated the transporters and enzymes involved in bile acid homeostasis such as Bsep, Oatp2, and Cyp3a2 in rats and BSEP, CYP3A4, and OATP2 in human cell lines. Moreover, SA-B suppressed NF-κB translocation into the nucleus, inhibited phosphorylation of p38 and JNK, and inhibited inflammation markers including IL-1β, IL-6, TGF-β, TNF-α, and COX-2 to extenuate cholestatic liver injury both in vivo and vitro. Taken together, our findings suggest that anti-cholestatic effects of SA-B may be associated with its ability to regulate NF-κB/IκB and MAPK inflammatory signaling pathways to inhibit inflammation and regulate transporters and enzymes to maintain bile acid homeostasis.

Mechanisms and in vitro models of drug-induced cholestasis

Cholestasis underlies one of the major manifestations of drug-induced liver injury. Drug-induced cholestatic liver toxicity is a complex process, as it can be triggered by a variety of factors that induce 2 types of biological responses, namely a deteriorative response, caused by bile acid accumulation, and an adaptive response, aimed at removing the accumulated bile acids. Several key events in both types of responses have been characterized in the past few years. In parallel, many efforts have focused on the development and further optimization of experimental cell culture models to predict the occurrence of drug-induced cholestatic liver toxicity in vivo. In this paper, a state-of-the-art overview of mechanisms and in vitro models of drug-induced cholestatic liver injury is provided.

Sortilin 1 Loss-of-Function Protects Against Cholestatic Liver Injury by Attenuating Hepatic Bile Acid Accumulation in Bile Duct Ligated Mice

Sortilin 1 (Sort1) is an intracellular trafficking receptor that mediates protein sorting in the endocytic or secretory pathways. Recent studies revealed a role of Sort1 in the regulation of cholesterol and bile acid (BA) metabolism. This study further investigated the role of Sort1 in modulating BA detoxification and cholestatic liver injury in bile duct ligated mice. We found that Sort1 knockout (KO) mice had attenuated liver injury 24 h after bile duct ligation (BDL), which was mainly attributed to less bile infarct formation. Sham-operated Sort1 KO mice had about 20% larger BA pool size than sham-operated wildtype (WT) mice, but 24 h after BDL Sort1 KO mice had significantly attenuated hepatic BA accumulation and smaller BA pool size. After 14 days BDL, Sort1 KO mice showed significantly lower hepatic BA concentration and reduced expression of inflammatory and fibrotic marker genes, but similar degree of liver fibrosis compared with WT mice. Unbiased quantitative proteomics revealed that Sort1 KO mice had increased hepatic BA sulfotransferase 2A1, but unaltered phase-I BA metabolizing cytochrome P450s or phase-III BA efflux transporters. Consistently, Sort1 KO mice showed elevated plasma sulfated taurocholate after BDL. Finally, we found that liver Sort1 was repressed after BDL, which may be due to BA activation of farnesoid x receptor. In conclusion, we report a role of Sort1 in the regulation of hepatic BA detoxification and cholestatic liver injury in mice. The mechanisms underlying increased hepatic BA elimination in Sort1 KO mice after BDL require further investigation.

Measuring Apoptosis and Necrosis in Cholestatic Liver Injury

Cholestasis can be induced by obstruction of bile ducts or intrahepatic toxicity of drugs and chemicals. However, the mode of cell death during cholestasis, i.e., apoptosis or necrosis, has been controversial. There are fundamental reasons for the controversies, both of which are discussed here, namely the design of experiments and the use of parameters with limited specificity for a certain mode of cell death. Based on the assumption that cholestatic liver injury is caused by accumulation of bile acids, rodent (mainly rat) hepatocytes have been exposed to hydrophobic, glycine-conjugated bile acids, which resulted in apoptotic cell death. The problems with this experimental design are that in rodents bile acids are predominantly taurine conjugated and rodent hepatocytes are never exposed to these levels of glycine-conjugated bile acids. In contrast, taurine-conjugated bile acids trigger inflammatory gene activation in rodent hepatocytes and a necro-inflammatory injury in vivo. On the other hand, human hepatocytes are more resistant to glycine-conjugated bile acids and die by necrosis when exposed to high biliary levels of these bile acids. In this chapter, we describe multiple assays including the caspase activity assay, which is specific for apoptosis, and the general cell death assays alanine aminotransferase or lactate dehydrogenase activities in cell culture medium or plasma. An increase in these enzyme activities without caspase activity indicates necrotic cell death. Thus, both the experimental design and the selection of cell death parameters are critical for the relevance of the experiments for the human pathophysiology.

Mechanisms of Drug-Induced Cholestasis

Cholestasis can be defined as any situation of impaired bile secretion with concomitant accumulation of bile acids in the liver or in the systemic circulation. A variety of factors may evoke cholestasis, including genetic disorders, metabolic pathologies, infectious diseases, immunogenic stimuli, and drugs. Drug-induced cholestasis is a mechanistically complex process. At least three triggering factors of drug-induced cholestasis have been described, including effects on drug transporters, various hepatocellular changes, and altered bile canaliculi dynamics. These stimuli induce two cellular responses, each typified by a number of key events, namely a deteriorative response activated by bile acid accumulation and an adaptive response aimed at decreasing the uptake and increasing the export of bile acids into and from the liver, respectively. The mechanistic scenario of drug-induced cholestasis is described in this chapter.

Danger-Associated Molecular Patterns (DAMPs): Molecular Triggers for Sterile Inflammation in the Liver

Inflammatory liver diseases in the absence of pathogens such as intoxication by xenobiotics, cholestatic liver injury, hepatic ischemia-reperfusion injury (I/R), non-alcoholic steatohepatitis (NASH), or alcoholic liver disease (ALD) remain threatening conditions demanding specific therapeutic options. Caused by various different noxae, all these conditions have been recognized to be triggered by danger- or death-associated molecular patterns (DAMPs), discompartmentalized self-structures released by dying cells. These endogenous, ectopic molecules comprise proteins, nucleic acids, adenosine triphosphate (ATP), or mitochondrial compounds, among others. This review resumes the respective modes of their release—passively by necrotic hepatocytes or actively by viable or apoptotic parenchymal cells—and their particular roles in sterile liver pathology. It addresses their sensors and the initial inflammatory responses they provoke. It further addresses a resulting second wave of parenchymal death that might be of different mode, boosting the release of additional, second-line DAMPs. Thus, triggering a more complex and pronounced response. Initial and secondary inflammatory responses comprise the activation of Kupffer cells (KCs), the attraction and activation of monocytes and neutrophil granulocytes, and the induction of type I interferons (IFNs) and their effectors. A thorough understanding of pathophysiology is a prerequisite for identifying rational therapeutic targets.

Advances in drug-induced cholestasis: Clinical perspectives, potential mechanisms and in vitro systems

Despite growing research, drug-induced liver injury (DILI) remains a serious issue of increasing importance to the medical community that challenges health systems, pharmaceutical industries and drug regulatory agencies. Drug-induced cholestasis (DIC) represents a frequent manifestation of DILI in humans, which is characterised by an impaired canalicular bile flow resulting in a detrimental accumulation of bile constituents in blood and tissues. From a clinical point of view, cholestatic DILI generates a wide spectrum of presentations and can be a diagnostic challenge. The drug classes mostly associated with DIC are anti-infectious, anti-diabetic, anti-inflammatory, psychotropic and cardiovascular agents, steroids, and other miscellaneous drugs. The molecular mechanisms of DIC have been investigated since the 1980s but they remain debatable. It is recognised that altered expression and/or function of hepatobiliary membrane transporters underlies some forms of cholestasis, and this and other concomitant mechanisms are very likely in DIC. Deciphering these processes may pave the ways for diagnosis, prognosis and prevention, for which currently major gaps and caveats exist. In this review, we summarise recent advances in the field of DIC, including clinical aspects, the potential mechanisms postulated so far and the in vitro systems that can be useful to investigate and identify new cholestatic drugs.

A Framework for Identifying Genotypic Information from Clinical Records: Exploiting Integrated Ontology Structures to Transfer Annotations between ICD Codes and Gene Ontologies

Although some methods are proposed for automatic ontology generation, none of them address the issue of integrating large-scale heterogeneous biomedical ontologies. We propose a novel approach for integrating various types of ontologies efficiently and apply it to integrate International Classification of Diseases, Ninth Revision, Clinical Modification (ICD9CM), and Gene Ontologies. This approach is one of the early attempts to quantify the associations among clinical terms (e.g., ICD9 codes) based on their corresponding genomic relationships. We reconstructed a merged tree for a partial set of GO and ICD9 codes and measured the performance of this tree in terms of associations' relevance by comparing them with two well-known disease-gene datasets (i.e., MalaCards and Disease Ontology). Furthermore, we compared the genomic-based ICD9 associations to temporal relationships between them from electronic health records. Our analysis shows promising associations supported by both comparisons suggesting a high reliability. We also manually analyzed several significant associations and found promising support from literature.

Review article: therapeutic bile acids and the risks for hepatotoxicity

BACKGROUND

Bile acids play important roles in cholesterol metabolism and signal through farnesoid X receptor and G protein-coupled receptors. Given their importance in liver biology, bile acid therapy enables therapeutic applications beyond the treatment of cholestatic liver disease. However, predicting hepatotoxicity of bile acids in humans is obscured due to inconsistent extrapolations of animal data to humans.

AIM

To review the evidence that could explain discordant bile acids hepatotoxicity observed in humans and animals.

METHOD

Literature search was conducted in PubMed using keywords "bile acid," "transporter," "hepatotoxicity," "clinical study," "animal study," "species difference," "mechanism," "genetic disorder." Relevant articles were selected for review.

RESULTS

Clinically significant hepatotoxicity was reported in response to certain bile acids, namely chenodeoxycholic acid, which was given a boxed warning for potential hepatotoxicity. The chemical structure, specifically the number and orientation of hydroxyl groups, significantly affects their hydrophobicity, an important factor in bile acid toxicity. Experimental studies show that hydrophobic bile acids can lead to liver injury through various mechanisms, such as death receptor signalling, mitochondrial dysfunction and inflammation. Although animal studies play a central role in investigating bile acid safety, there are considerable differences in bile acid composition, metabolism and hepatobiliary disposition across species. This does not allow appropriate safety inference, especially for predicting hepatotoxicity in humans. Exploring evidences stemming from inborn errors, genetic models of disease and toxicology studies further improves an understanding of bile acid hepatotoxicity.

CONCLUSION

Species differences should be considered in the development of bile acid related therapeutics. Although the mechanism of bile acid hepatotoxicity is still not fully understood, continued mechanistic studies will deepen our understanding.

Evaluation of liver function by means of serum cytokeratin 18 and hepatocyte growth factor levels in patients with obstructive jaundice

OBJECTIVE

To evaluate the serum levels of cytokeratin 18 (CK18) and hepatocyte growth factor (HGF) in obstructive jaundice patients before and after treatment and thereby to detect the possible role of CK18 and HGF in patients with obstructive jaundice.

PATIENTS AND METHODS

Forty patients who had obstructive jaundice and 40 healthy control subjects were included in the study. Patients were treated using percutaneous, endoscopic or surgical approaches. Blood samples were obtained at the day before and 7 days after the intervention for obstructive jaundice. Serum HGF and CK18 concentrations were determined by ELISA method.

RESULTS

There were statistically significant decreases in HGF, CK18, total bilirubin and direct bilirubin serum levels, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyltransferase, and alkaline phosphatase activities and white blood cell count when compared with pre-treatment levels.

CONCLUSION

Evaluating pre- and post-treatment serum HGF and CK18 levels suggested that there was an apoptosis in obstructive jaundice patients and this apoptosis decreased after the decompression of the biliary tract. We also demonstrated that HGF levels were altered at biliary obstruction compared to healthy controls and the levels of this biomarker also decreased after decompression of biliary obstruction. We concluded that these biomarkers can be used as predictors of liver injury in biliary obstruction.

Mitochondrial dysfunction as a mechanism of drug-induced hepatotoxicity: current understanding and future perspectives

Mitochondria are critical cellular organelles for energy generation and are now also recognized as playing important roles in cellular signaling. Their central role in energy metabolism, as well as their high abundance in hepatocytes, make them important targets for drug-induced hepatotoxicity. This review summarizes the current mechanistic understanding of the role of mitochondria in drug-induced hepatotoxicity caused by acetaminophen, diclofenac, anti-tuberculosis drugs such as rifampin and isoniazid, anti-epileptic drugs such as valproic acid and constituents of herbal supplements such as pyrrolizidine alkaloids. The utilization of circulating mitochondrial-specific biomarkers in understanding mechanisms of toxicity in humans will also be examined. In summary, it is well-established that mitochondria are central to acetaminophen-induced cell death. However, the most promising areas for clinically useful therapeutic interventions after acetaminophen toxicity may involve the promotion of adaptive responses and repair processes including mitophagy and mitochondrial biogenesis, In contrast, the limited understanding of the role of mitochondria in various aspects of hepatotoxicity by most other drugs and herbs requires more detailed mechanistic investigations in both animals and humans. Development of clinically relevant animal models and more translational studies using mechanistic biomarkers are critical for progress in this area.

Relevance for patients:This review focuses on the role of mitochondrial dysfunction in liver injury mechanisms of clinically important drugs like acetaminophen, diclofenac, rifampicin, isoniazid, amiodarone and others. A better understanding ofthe mechanisms in animal models and their translation to patients will be critical for the identification of new therapeutic targets.

Evaluation of plasma microRNA-122, high-mobility group box 1 and keratin-18 concentrations to stratify acute gallstone disease: a pilot observational cohort study in an emergency general surgery unit

OBJECTIVE

To obtain pilot data to evaluate the discriminatory power of biomarkers microRNA-122 (miR-122), high-mobility group box 1 (HMGB1), full-length keratin-18 (flk-18) and caspase-cleaved keratin-18 (cck-18) in plasma to identify potential biliary complications that may require acute intervention.

DESIGN

An observational biomarker cohort pilot study.

SETTING

In a Scottish University teaching hospital for 12 months beginning on 3 September 2014.

PARTICIPANTS

Blood samples were collected from adults (≥16 years old) referred with acute biliary-type symptoms who have presented to hospital within 24 hours prior were recruited. Patients unable or refused to give informed consent or were transferred from a hospital outside the National Health Service regional trust were excluded.

PRIMARY OUTCOME MEASURES

To evaluate whether circulating miR-122, HMGB1, flk-18 and cck-18 can discriminate between people with and without gallstone disease and uncomplicated from complicated gallstone disease during the first 24 hours of hospital admission.

RESULTS

300 patients were screened of which 285 patients were included. Plasma miR-122, cck-18 and flk-18 concentrations were increased in patients with gallstones compared with those without (miR-122: median: 2.89×104 copies/mL vs 0.90×104 copies/mL (p<0.001); cck-18: 121.2 U/L vs 103.5 U/L (p=0.031); flk-18: 252.4 U/L vs 145.1 U/L (p<0.001)). Uncomplicated gallstone disease was associated with higher miR-122 and cck-18 concentrations than complicated disease (miR-122: 5.72×104 copies/mL vs 2.26×104 copies/mL (p=0.023); cck-18: 139.7 U/L vs 113.6 U/L (p=0.047)). There was no significant difference in HMGB1 concentration between patients with and without gallstones (p=0.559). Separation between groups for all biomarkers was modest.

CONCLUSION

miR-122 and keratin-18 plasma concentrations are elevated in patients with gallstones. However, this result is confounded by the association between biomarker concentrations, age and gender. In this pilot study, miR-122 and keratin-18 were not sufficiently discriminatory to be progressed as clinically useful biomarkers in this context.

Assessment of serum bile acid profiles as biomarkers of liver injury and liver disease in humans

To assess the potential of individual bile acids (IBA) and their profiles as mechanistic biomarkers of liver injury for humans in real world situations, we interrogated samples collected under minimum controlled conditions (ie subjects were not fasted). Total bile acids (TBA) have been considered to be biomarkers of liver injury for decades, and more recently, monitoring of IBA has been proposed for differentiation of variety of etiologies of liver injury. We established a LC-MS/MS methodology to analyze nine IBA, generated reference ranges, and examined effects of age, gender, and ethnicity for each IBA. Furthermore, we evaluated the ability of IBA and their profiles to detect hepatic injury in subjects with a broad range of liver impairments. To date, our study utilized the largest total cohort of samples (N = 645) that were divided into 2 groups, healthy or liver impaired, to evaluate IBA as biomarkers. The TBA serum levels in the Asian ethnic group trended higher when compared to other ethnic groups, and the serum concentrations of IBA, such as glycocholic acid (GCA), glycochenodeoxycholic acid (GCDCA), chenodeoxycholic acid (CDCA), and taurochenoxycholic acid (TCDCA) were significantly increased. To our knowledge, this report is the first to describe ethnic differences in serum concentrations of IBAs. In patients with hepatic impairments, with the exception of deoxycholic acid (DCA), the concentrations of IBAs were significantly elevated when compared with healthy subjects. The conjugated bile acids displayed greater differences between healthy subjects and subjects with hepatic impairments than non-conjugated bile acids. Furthermore, the subjects with hepatic impairments exhibited distinct profiles (signatures) of IBAs that clustered subjects according the nature of their liver impairments. Although additional studies are needed, our data suggested that the analysis of IBA has the potential to become useful for differentiation of various forms of liver injury.

Dexamethasone restores transforming growth factor-β activated kinase 1 expression and phagocytosis activity of Kupffer cells in cholestatic liver injury

The role of transforming growth factor-β activated kinase 1 (TAK1) in modulating the function of Kupffer cells (KCs) within cholestatic livers remains unclear. This study examined the immunopharmacological action of dexamethasone (DEX) in modulating hepatic TAK1 expression and related signaling activity in a rat model of bile duct ligation-mimicked obstructive jaundice. The in vitro effects of DEX on porcine biliary extract (PBE)-modulated gene expression and phagocytosis of KCs were examined using a rat alveolar macrophage cell line (NR8383 cells). Although DEX therapy did not restore the downregulated TAK1 expression and phosphorylation, it significantly attenuated the upregulation of high-mobility group box 1 expression and caspase-3 activation in whole liver extracts of cholestatic rats, possibly via enhancing extracellular signal-regulated kinase-mediated signaling. Dual immunofluorescence staining of cholestatic livers and western detection on primary KCs isolated from cholestatic livers identified that DEX treatment indeed increased both the expression and phosphorylation levels of TAK1 in the KCs of cholestatic livers. In vitro studies using alveolar NR8383 macrophages with KC-characteristic gene expression further demonstrated that DEX not only repressed the pro-inflammatory cytokine production including with respect to interleukin (IL)-1β and IL-6, but also enhanced gene expression of TAK1 and a phagocytic marker, natural-resistance-associated macrophage protein 1, under PBE-mimicked cholestatic conditions. However, WST-1 assay showed that DEX did not protect NR8383 macrophages against the PBE-induced cytotoxicity. Immunofluorescence visualization of cellular F-actin by phalloidin suggested that DEX sustained the PBE-induced phagocytosis morphology of NR8383 macrophages. In conclusion, DEX treatment may pharmacologically restore the expression and activity of TAK1 in KCs, and sustain the phagocytic phenotype of KCs in cholestatic livers.

MiR-122 and other microRNAs as potential circulating biomarkers of drug-induced liver injury

INTRODUCTION

Drug-induced liver injury (DILI) is a severe adverse drug reaction which is of major concern to patients, clinicians and the pharmaceutical industry. Accurate and rapid detection of DILI is important for patient stratification and treatment in the clinic and benefits preclinical drug design and risk assessment. MicroRNAs (miRNAs) offer a potential new and improved class of circulating biomarkers of DILI over the current gold standard biomarkers. Areas covered: This review highlights the shortcomings of the currently used panel of biomarkers and how miRNAs, primarily miR-122, show an improved level of specificity and sensitivity in the prediction of DILI. Furthermore, the use of miRNAs as potential markers of progression of DILI and specific zonated damage within the liver is discussed. Expert commentary: MiRNAs offer more sensitive and specific markers over the current biomarkers for DILI. Combinations of different miRNAs may be able to relay the location of DILI and the progression of disease. More studies using different hepatotoxins apart from acetaminophen will ultimately strengthen the case for the clinical introduction of miRNAs as biomarkers of DILI.

Cell Death and Prognosis of Mortality in Alcoholic Hepatitis Patients Using Plasma Keratin-18

Alcoholic liver disease encompasses the progressive stages of liver dysfunction that culminates in alcoholic cirrhosis (AC) and in severe cases alcoholic hepatitis (AH). Currently, prognostic scores have limited specificity and sensitivity. Plasma keratin-18 (K18) levels are elevated during liver disease and may be biomarkers of outcome. The objective of this study was to determine if total K18 (M65) or caspase-cleaved K18 (M30) levels were different between AC and AH patients. M65 and M30 levels were measured in the plasma of consented healthy controls and patients with AC and AH. Cell death was assessed by TUNEL staining and caspase activity. M65 and M30 values were significantly higher in AC patients compared to healthy controls and further increased in AH patients. The M65 values and the M30/M65 ratios of nonsurviving AH patients were significantly elevated above their surviving counterparts and healthy controls. Statistical analysis indicated that M30/M65 ratios outperformed current indices for accurately distinguishing the prognosis of AH patients. These scores occurred with minimal increase in plasma cell death markers such as ALT and AST. Serum caspase activity, TUNEL staining, and M30 immunohistochemistry in biopsies indicated that serum and tissue values may not correlate well with overall cell death. In conclusion, both M65 and M30 differentiate AH from AC patients, and M65 values and the M30/M65 ratio are capable of predicting early stage mortality; however, they may not accurately reflect pure hepatocyte cell death in these populations, as they do not strongly correlate with traditional cell death markers.

miRNA profiling for diagnosis, prognosis and stratification of cancer treatment in cholangiocarcinoma

Cholangiocarcinoma (CCA) is a lethal malignancy originating from the biliary tract epithelium. Most patients are diagnosed at an advanced stage. Even after resection with curative intent, prognosis remains poor. Previous studies have reported the evolving role of miRNAs as novel biomarkers in cancer diagnosis, prognostication and chemotherapy response. Various miRNAs, such as miR-21, miR-26, miR-122 and miR-150, have been identified as possible blood-based biomarkers for noninvasive diagnosis of CCA. Moreover, epithelial-mesenchymal transition (EMT)- and angiogenesis-associated miRNAs have been implicated in tumor cell dissemination and are able to determine clinical outcome. In fact, miRNAs involved in cell survival might even determine chemotherapy response. This review provides an overview of known miRNAs as CCA-specific biomarkers.

Mechanisms of bile acid mediated inflammation in the liver

Bile acids are synthesized in the liver and are the major component in bile. Impaired bile flow leads to cholestasis that is characterized by elevated levels of bile acid in the liver and serum, followed by hepatocyte and biliary injury. Although the causes of cholestasis have been extensively studied, the molecular mechanisms as to how bile acids initiate liver injury remain controversial. In this chapter, we summarize recent advances in the pathogenesis of bile acid induced liver injury. These include bile acid signaling pathways in hepatocytes as well as the response of cholangiocytes and innate immune cells in the liver in both patients with cholestasis and cholestatic animal models. We focus on how bile acids trigger the production of molecular mediators of neutrophil recruitment and the role of the inflammatory response in this pathological process. These advances point to a number of novel targets where drugs might be judged to be effective therapies for cholestatic liver injury.

Mechanisms of bile acid mediated inflammation in the liver

Bile acids are synthesized in the liver and are the major component in bile. Impaired bile flow leads to cholestasis that is characterized by elevated levels of bile acid in the liver and serum, followed by hepatocyte and biliary injury. Although the causes of cholestasis have been extensively studied, the molecular mechanisms as to how bile acids initiate liver injury remain controversial. In this chapter, we summarize recent advances in the pathogenesis of bile acid induced liver injury. These include bile acid signaling pathways in hepatocytes as well as the response of cholangiocytes and innate immune cells in the liver in both patients with cholestasis and cholestatic animal models. We focus on how bile acids trigger the production of molecular mediators of neutrophil recruitment and the role of the inflammatory response in this pathological process. These advances point to a number of novel targets where drugs might be judged to be effective therapies for cholestatic liver injury.

Induction of chronic cholestasis without liver cirrhosis - Creation of an animal model

AIM

To analyze time intervals of inflammation and regeneration in a cholestatic rat liver model.

METHODS

In 36 Lewis rats, divided into six groups of 6 animals (postoperative observation periods: 1, 2, 3, 4, 6, 8 wk), the main bile duct was ligated with two ligatures and observed for the periods mentioned above. For laboratory evaluation, cholestasis parameters (bilirubin, γ-GT), liver cell parameters (ASAT, ALAT) and liver synthesis parameters (quick, albumin) were determined. For histological analysis, HE, EvG, ASDCL and HMGB-1 stainings were performed. Furthermore, we used the mRNA of IL-33, GADD45a and p-21 for analyzing cellular stress and regeneration in cholestatic rats.

RESULTS

In chemical laboratory and histological evaluation, a distinction between acute and chronic cholestatic liver injury with identification of inflammation and regeneration could be demonstrated by an increase in cholestasis (bilirubin: 1-wk group, 156.83 ± 34.12 μmol/L, P = 0.004) and liver cell parameters (ASAT: 2-wk group, 2.1 ± 2.19 μmol/L.s, P = 0.03; ALAT: 2-wk group, 1.03 ± 0.38 μmol/L.s, P = 0.03) after bile duct ligation (BDL). Histological evaluation showed an increase of bile ducts per portal field (3-wk group, 48 ± 6.13, P = 0.004) during the first four weeks after bile duct ligation. In addition to inflammation, which is an expression of acute cholestasis, there was an increase of necrotic areas in the histological sections (2-wk group, 1.38% ± 2.28% per slide, P = 0.002). Furthermore, the inflammation could be verified by ASDCL (4-wk group, 22 ± 5.93 positive cells per portal field, P = 0.041) and HMGB-1 [2-wk group, 13 ± 8.18 positive cells per field of view (FoV), P = 0.065] staining. Therefore, in summary of the laboratory evaluation and histological studies, acute cholestasis could be found during the first four weeks after bile duct ligation. Subsequently, the described parameters declined so that chronic cholestasis could be assumed. For quantification of secondary biliary cirrhosis, eosin staining was performed, which did not reveal any signs of liver remodeling, thus precluding the development of a chronic cholestasis model. Additionally, to establish the chronic cholestasis model, we evaluated liver regeneration capacity through measurements of IL-33, p-21 and GADD45a mRNA.

CONCLUSION

We created a chronic cholestasis model. The point of inflammatory and regenerative balance was reached after four weeks. This finding should be used for experimental approaches dealing with chronic cholestatic liver damage.

Serum miRNA signature diagnoses and discriminates murine colitis subtypes and predicts ulcerative colitis in humans

Inflammatory bowel disease (IBD) is difficult to diagnose due to nonspecific and variable symptoms, and lack of reliable diagnostic tests. Current methods are invasive, non-sensitive, non-predictive, and do not easily discriminate between its two main forms. Consequently, there remains a great need for reliable serum markers for IBD. Here, using a longitudinal study of various mouse models of colitis, we identified a serum miRNA signature that indicated the development of colitis and discriminated between inflammations of various origins (colitis from arthritis). Unlike the existing biomarkers, the newly identified signature also serves to distinguish individuals at risk, predict the type of inflammation, and evaluate the response to therapeutics. Moreover, the miRNA signature identified in mice predicted ulcerative colitis with 83.3% accuracy. In future, the signature identified herein could play a central role in monitoring inflammatory disorders and therapeutic responses in patients, thereby paving the way for personalized medicine.

Paeoniflorin ameliorates cholestasis via regulating hepatic transporters and suppressing inflammation in ANIT-fed rats

Paeoniflorin has shown the obvious effect on cholestasis according to our previous research. However, its mechanism has not been absolutely explored yet. This study aims at evaluating the potential effect of paeoniflorin on alpha-naphthylisothiocyanate (ANIT) -induced cholestasis by inhibiting nuclear factor kappa-B (NF-κB) and simultaneously regulating hepatocyte transporters. Cholestasis was induced by administration of ANIT. The effect of paeoniflorin on serum indices such as total bilirubin (TBIL), direct bilirubin (DBIL), aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), γ-glutamyltranspeptidase (γ-GT), total bile acid (TBA) and histopathology of liver were determined. Liver protein levels of NF-κB, interleukin 1β (IL-1β) and the hepatocyte transporters such as Na+/taurocholate cotransporting polypeptide (NTCP), bile salt export pump (BSEP), multidrug resistance-associated protein 2 (MRP2) and cholesterol 7α-hydroxylase (Cyp7a1) were investigated by western blotting. The results demonstrated that paeoniflorin could decrease serum ALT, AST, ALP, γ-GT, TBIL, DBIL and TBA in ANIT-treated rats. Histological examination revealed that rats treated with paeoniflorin represented fewer neutrophils infiltration, edema and necrosis in liver tissue compared with ANIT rats. Moreover, paeoniflorin significantly reduced the over expressions of NF-κB and IL-1β induced by ANIT in liver tissue. In addition, the relative protein expressions of NTCP, BSEP, MRP2 but not Cyp7a1 were also restored by paeoniflorin. The potential mechanism of paeoniflorin in alleviating ANIT-induced cholestasis seems to be related to reduce the over expressions of NF-κB and hepatocyte transporters such as NTCP, BSEP as well as MRP2.

Bile acids initiate cholestatic liver injury by triggering a hepatocyte-specific inflammatory response

Mechanisms of bile acid-induced (BA-induced) liver injury in cholestasis are controversial, limiting development of new therapies. We examined how BAs initiate liver injury using isolated liver cells from humans and mice and in-vivo mouse models. At pathophysiologic concentrations, BAs induced proinflammatory cytokine expression in mouse and human hepatocytes, but not in nonparenchymal cells or cholangiocytes. These hepatocyte-specific cytokines stimulated neutrophil chemotaxis. Inflammatory injury was mitigated in Ccl2^-/- mice treated with BA or after bile duct ligation, where less hepatic infiltration of neutrophils was detected. Neutrophils in periportal areas of livers from cholestatic patients also correlated with elevations in their serum aminotransferases. This liver-specific inflammatory response required BA entry into hepatocytes via basolateral transporter Ntcp. Pathophysiologic levels of BAs induced markers of ER stress and mitochondrial damage in mouse hepatocytes. Chemokine induction by BAs was reduced in hepatocytes from Tlr9^-/- mice, while liver injury was diminished both in conventional and hepatocyte-specific Tlr9^-/- mice, confirming a role for Tlr9 in BA-induced liver injury. These findings reveal potentially novel mechanisms whereby BAs elicit a hepatocyte-specific cytokine-induced inflammatory liver injury that involves innate immunity and point to likely novel pathways for treating cholestatic liver disease.

Dioscin Protects ANIT-Induced Intrahepatic Cholestasis Through Regulating Transporters, Apoptosis and Oxidative Stress

Intrahepatic cholestasis, a clinical syndrome, is caused by excessive accumulation of bile acids in body and liver. Proper regulation of bile acids in liver cells is critical for liver injury. We previously reported the effects of dioscin against α-naphthylisothio- cyanate (ANIT)-induced cholestasis in rats. However, the pharmacological and mechanism data are limited. In our work, the animals of rats and mice, and Sandwich-cultured hepatocytes (SCHs) were caused by ANIT, and dioscin was used for the treatment. The results showed that dioscin markedly altered relative liver weights, restored ALT, AST, ALP, TBIL, GSH, GSH-Px, MDA, SOD levels, and rehabilitated ROS level and cell apoptosis. In mechanism study, dioscin not only significantly regulated the protein levels of Ntcp, OAT1, OCT1, Bsep and Mrp2 to accelerate bile acids excretion, but also regulated the expression levels of Bak, Bcl-xl, Bcl-2, Bax, Caspase 3 and Caspase 9 in vivo and in vitro to improve apoptosis. In addition, dioscin markedly inhibited PI3K/Akt pathway and up-regulated the levels of Nrf2, GCLc, GCLm, NQO1 and HO-1 against oxidative stress (OS) caused by bile acids. These results were further validated by inhibition of PI3K and Akt using the inhibitors of wortmannin and perifosine in SCHs. Our data showed that dioscin had good action against ANIT-caused intrahepatic cholestasis through regulating transporters, apoptosis and OS. This natural product can be considered as one active compound to treat intrahepatic cholestasis in the future.

The impact of sterile inflammation in acute liver injury

BACKGROUND

The liver has a number of functions in innate immunity. These functions predispose the liver to innate immune-mediated liver injury when inflammation goes unchecked. Significant progress has been made in the last 25 years on sterile inflammatory liver injury in a number of models; however, a great deal of controversy and many questions about the nature of sterile inflammation still exist.

AIM

The goal of this article is to review sterile inflammatory liver injury using both a basic approach to what constitutes the inflammatory injury, and through examination of current models of liver injury and inflammation. This information will be tied to human patient conditions when appropriate.

RELEVANCE FOR PATIENTS

Inflammation is one of the most critical factors for managing in-patient liver disease in a number of scenarios. More information is needed for both scientists and clinicians to develop rational treatments.

Novel circulating- and imaging-based biomarkers to enhance the mechanistic understanding of human drug-induced liver injury

Liver safety biomarkers in current clinical practice are recognized to have certain shortcomings including their representation of general cell death and thus lacking in indicating the specific underlying mechanisms of injury. An informative panel of circulating- and imaging-based biomarkers, will allow a more complete understanding of the processes involved in the complex and multi-cellular disease of drug-induced liver injury; potentially preceding and therefore enabling prediction of disease progression as well as directing appropriate, existing or novel, therapeutic strategies. Several putative liver safety biomarkers are under investigation as discussed throughout this review, informing on a multitude of hepatocellular mechanisms including: early cell death (miR-122), necrosis (HMGB1, K18), apoptosis, (K18), inflammation (HMGB1), mitochondrial damage (GLDH, mtDNA), liver dysfunction (MRI, MSOT) and regeneration (CSF1). These biomarkers also hold translational value to provide important read across between in vitro-in vivo and clinical test systems. However, gaps in our knowledge remain requiring further focussed research and the ultimate qualification of key exploratory biomarkers. Relevance for patients: this novel multi-modal approach of assessing drug-induced liver injury could potentially enable better patient stratification and enhance treatment strategies. Ultimately, this could reduce unnecessary treatment, also decreasing hospital bed occupancy, whilst ensuring early and accurate identification of patients needing intervention.