Cytokine profiles in acute liver injury-Results from the US Drug-Induced Liver Injury Network (DILIN) and the Acute Liver Failure Study Group

Comparative analysis of gene expression between mice and humans in acetaminophen-induced liver injury by integrating bioinformatics analysis

OBJECTIVE

Mice are routinely utilized as animal models of drug-induced liver injury (DILI), however, there are significant differences in the pathogenesis between mice and humans. This study aimed to compare gene expression between humans and mice in acetaminophen (APAP)-induced liver injury (AILI), and investigate the similarities and differences in biological processes between the two species.

METHODS

A pair of public datasets (GSE218879 and GSE120652) obtained from GEO were analyzed using "Limma" package in R language, and differentially expressed genes (DEGs) were identified, including co-expressed DEGs (co-DEGs) and specific-expressed DEGS (specific-DEGs). Analysis of Gene Set Enrichment Analysis (GSEA), Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were performed analyses for specific-DEGs and co-DEGs. The co-DEGs were also used to construct transcription factor (TF)-gene network, gene-miRNA interactions network and protein-protein interaction (PPI) network for analyzing hub genes.

RESULTS

Mouse samples contained 1052 up-regulated genes and 1064 down-regulated genes, while human samples contained 1156 up-regulated genes and 1557 down-regulated genes. After taking the intersection between the DEGs, only 154 co-down-regulated and 89 co-up-regulated DEGs were identified, with a proportion of less than 10%. It was suggested that significant differences in gene expression between mice and humans in drug-induced liver injury. Mouse-specific-DEGs predominantly engaged in processes related to apoptosis and endoplasmic reticulum stress, while human-specific-DEGs were concentrated around catabolic process. Analysis of co-regulated genes reveals showed that they were mainly enriched in biosynthetic and metabolism-related processes. Then a PPI network which contains 189 nodes and 380 edges was constructed from the co-DEGs and two modules were obtained by Mcode. We screened out 10 hub genes by three algorithms of Degree, MCC and MNC, including CYP7A1, LSS, SREBF1, FASN, CD44, SPP1, ITGAV, ANXA5, LGALS3 and PDGFRA. Besides, TFs such as FOXC1, HINFP, NFKB1, miRNAs like mir-744-5p, mir-335-5p, mir-149-3p, mir-218-5p, mir-10a-5p may be the key regulatory factors of hub genes.

CONCLUSIONS

The DEGs of AILI mice models and those of patients were compared, and common biological processes were identified. The signaling pathways and hub genes in co-expression were identified between mice and humans through a series of bioinformatics analyses, which may be more valuable to reveal molecular mechanisms of AILI.

The Use and Potential Benefits of N-Acetylcysteine in Non-Acetaminophen Acute Liver Failure: An Etiology-Based Review

Acute liver failure represents a life-threatening organ dysfunction with high mortality rates and an urgent need for liver transplantation. The etiology of the disease varies widely depending on various socio-economic factors and is represented mainly by paracetamol overdose and other drug-induced forms of liver dysfunction in the developed world and by viral hepatitis and mushroom poisoning in less developed countries. Current medical care constitutes either specific antidotes or supportive measures to ensure spontaneous recovery. Although it has been proven to have beneficial effects in paracetamol-induced liver failure, N-acetylcysteine is widely used for all forms of acute liver failure. Despite this, few well-designed studies have been conducted on the assessment of the potential benefits, dose regimens, or route of administration of N-acetylcysteine in non-acetaminophen liver failure. This review aims to summarize the current evidence behind the use of this drug in different forms of liver failure.

Altered profiles of circulating cytokines in chronic liver diseases (NAFLD/HCC): Impact of the PNPLA3I148M risk allele

BACKGROUND

Individuals carrying the risk variant p.I148M of patatin-like phospholipase domain-containing protein 3 (PNPLA3) have a higher susceptibility to fatty liver diseases and associated complications, including HCC, a cancer closely linked to chronic inflammation. Here, we assessed circulating cytokine profiles for patients with chronic liver diseases genotyped for PNPLA3.

METHODS

Serum concentrations of 22 cytokines were measured by multiplex sandwich-ELISA. The cohort comprised 123 individuals: 67 patients with NAFLD without cirrhosis (57 steatosis, 10 NASH), 24 patients with NAFLD with cirrhosis, 21 patients with HCC (15 cirrhosis), and 11 healthy controls. Receiver operator characteristic analyses were performed to assess the suitability of the cytokine profiles for the prediction of steatosis, cirrhosis, and HCC.

RESULTS

HGF, IL-6, and IL-8 levels were increased in patients, with ∼2-fold higher levels in patients with cirrhosis versus healthy, while platelet derived growth factor-BB (PDGF-BB) and regulated on activation, normal T cell expressed and secreted (RANTES) showed lower concentrations compared to controls. Migration inhibitory factor and monocyte chemoattractant protein-1 (MCP-1) were found at higher levels in NAFLD samples (maximum: NAFLD-cirrhosis) versus healthy controls and HCC samples. In receiver operator characteristic analyses, migration inhibitory factor, IL-8, IL-6, and monocyte chemoattractant protein-1 yielded high sensitivity scores for predicting noncirrhotic NAFLD (vs. healthy). The top combination to predict cirrhosis was HGF plus PDGF-BB. Migration inhibitory factor performed best to discriminate HCC from NAFLD; the addition of monokine induced gamma (MIG), RANTES, IL-4, macrophage colony-stimulating factor (M-CSF), or IL-17A as second parameters further increased the AUC values (> 0.9). No significant impact of the PNPLA3I148M allele on cytokine levels was observed in this cohort.

CONCLUSIONS

Cytokines have biomarker potential in patients with fatty liver, possibly suited for early HCC detection in patients with fatty liver. Patients carrying the PNPLA3 risk allele did not present significantly different levels of circulating cytokines.

Serum levels of IL-6/IL-10/GLDH may be early recognition markers of anti-tuberculosis drugs (ATB) -induced liver injury

To explore the potential value of serum glutamate dehydrogenase (GLDH) combined with inflammatory cytokines as diagnostic biomarkers for anti-tuberculosis drug -induced liver injury (ATB-DILI). We collected the residual serum from the patients who met the criteria after liver function tests. We have examined these parameters including GLDH which were determined by enzyme-linked immunosorbent assay and cytokines which were determined by cytokine combination detection kit. Multivariate logistics stepwise forward regression was applied to establish regression models. A total of 138 tuberculosis patients were included in the diagnostic markers study of ATB-DILI, including normal liver function group (n = 108) and ATB-DILI group(n = 30). Serum GLDH, IL-6 and IL-10 levels were significantly increased in the ATB-DILI group. Receiver operating characteristic curve (ROC) curve showed that the area under curve (AUC) of serum GLDH, IL-6 and IL-10 for the diagnosis of ATB-DILI were 0.870, 0.714 and 0.811, respectively. In logistic regression modeling, the AUC of GLDH combined with IL-10 as an ATB-DILI marker is 0.912. Serum IL-6、IL-10 and GLDH levels began to rise preceded the increase in ALT by 7 days, with significant differences in IL-6 compared with 7 days. Serum GLDH, IL-6 and IL-10 levels were correlated with the severity of liver injury. In conclusion, we found that GLDH, IL-6 and IL-10 alone as diagnostic markers of ATB-DILI had good diagnostic efficacy. Logistic regression model established by GLDH and IL-10 had better diagnostic efficacy and IL-6 may be an early predictor of liver injury in the setting of ATB poisoning.

The high level of IL-1β in the serum of ACLF patients induces increased IL-8 expression in hUC-MSCs and reduces the efficacy of hUC-MSCs in liver failure

BACKGROUND

Stem cells play a therapeutic role mainly through immunoregulation. However, the immunomodulatory function of stem cells may be affected by inflammation-related factors in patients' serum. Therefore, this study aims to investigate the possible mechanism by which acute-on-chronic liver failure (ACLF) patient serum influences the efficacy of hUC-MSCs.

METHODS

The serum of surviving and dead ACLF patients was collected to culture hUC-MSCs in vitro, and the hUC-MSCs cultured in the serum of ACLF patients were used to treat acute liver failure (ALF) rats. The therapeutic effect on the rats was evaluated by a survival curve, the transaminase level and liver histopathology. The expression of cytokines in hUC-MSCs was detected by Q-PCR and ELISA.

RESULTS

Serum pretreatment reduced the therapeutic effect of hUC-MSCs on ALF, especially pretreatment in the serum from dead ACLF patients. After hUC-MSCs were cultured in the serum of surviving or dead ACLF patients, the most differentially expressed factor was IL-8. Interfering with the expression of IL-8 in hUC-MSCs can improve the therapeutic effect of hUC-MSCs on ALF. The high level of IL-1β in the serum of dead ACLF patients causes the increased expression of IL-8 in hUC-MSCs through the activation of the NF-κB signaling pathway. Meanwhile, we found that the neutralizing IL-1β in serum from dead ACLF patients can improve the therapeutic effect of hUC-MSCs on ALF.

CONCLUSION

The high level of IL-1β in ACLF serum can promote the expression of IL-8 in hUC-MSCs through the NF-κB signaling pathway, thus reducing the effect of hUC-MSCs on ALF.

Correlation between serum cytokines and clinicopathological features in patients with drug-induced liver injury

Objectives: Changes in serum levels of cytokines have been proposed as possible biological markers of tissue damage, including drug-induced liver injury (DILI). Here, we aimed to screen cytokine markers that have guiding significance for the degree of inflammation of DILI. Patients and methods: 54 patients with DILI were retrospectively analyzed as the experimental group, and 14 healthy subjects were randomly selected as the control group. A total of 20 cytokines were detected by using a cytokine protein antibody chip, and differentially expressed proteins were screened. Results: There were significant differences in serum cytokines between DILI patients and healthy controls. Compared with the control group, the DILI group expressed 11 differential proteins. IL-8, TNF RII, TNFα, TNF RI, MIP-1β, MIP-1α, and IL-1β were differentially expressed in DILI patients with different degrees of inflammation from G1 to G4. MIG, IL-12p40, and IL-10 were differentially expressed in the higher degree of inflammation groups (G2, G3, and G4 groups). Tissue inhibitor of metalloproteinases-1 (TIMP-1) was differentially expressed in the group with the highest inflammation degree (G4 group). Chemokine C-C motif ligand 1 (I-309) was only differentially expressed in the lowest inflammation group (G1 group). Conclusion: The changes and differential expression of specific cytokine levels were helpful for evaluating different degrees of inflammation of DILI.

The immunological mechanisms and therapeutic potential in drug-induced liver injury: lessons learned from acetaminophen hepatotoxicity

Acute liver failure caused by drug overdose is a significant clinical problem in developed countries. Acetaminophen (APAP), a widely used analgesic and antipyretic drug, but its overdose can cause acute liver failure. In addition to APAP-induced direct hepatotoxicity, the intracellular signaling mechanisms of APAP-induced liver injury (AILI) including metabolic activation, mitochondrial oxidant stress and proinflammatory response further affect progression and severity of AILI. Liver inflammation is a result of multiple interactions of cell death molecules, immune cell-derived cytokines and chemokines, as well as damaged cell-released signals which orchestrate hepatic immune cell infiltration. The immunoregulatory interplay of these inflammatory mediators and switching of immune responses during AILI lead to different fate of liver pathology. Thus, better understanding the complex interplay of immune cell subsets in experimental models and defining their functional involvement in disease progression are essential to identify novel therapeutic targets for the treatment of AILI. Here, this present review aims to systematically elaborate on the underlying immunological mechanisms of AILI, its relevance to immune cells and their effector molecules, and briefly discuss great therapeutic potential based on inflammatory mediators.

A non-human primate model of acute liver failure suitable for testing liver support systems

Acute hepatic failure is associated with high morbidity and mortality for which the only definitive therapy is liver transplantation. Some fraction of those who undergo emergency transplantation have been shown to recover native liver function when transplanted with an auxiliary hepatic graft that leaves part of the native liver intact. Thus, transplantation could have been averted with the development and use of some form of hepatic support. The costs of developing and testing liver support systems could be dramatically reduced by the availability of a reliable large animal model of hepatic failure with a large therapeutic window that allows the assessment of efficacy and timing of intervention. Non-lethal forms of hepatic injury were examined in combination with liver-directed radiation in non-human primates (NHPs) to develop a model of acute hepatic failure that mimics the human condition. Porcine hepatocyte transplantation was then tested as a potential therapy for acute hepatic failure. After liver-directed radiation therapy, delivery of a non-lethal hepatic ischemia-reperfusion injury reliably and rapidly generated liver failure providing conditions that can enable pre-clinical testing of liver support or replacement therapies. Unfortunately, in preliminary studies, low hepatocyte engraftment and over-immune suppression interfered with the ability to assess the efficacy of transplanted porcine hepatocytes in the model. A model of acute liver failure in NHPs was created that recapitulates the pathophysiology and pathology of the clinical condition, does so with reasonably predictable kinetics, and results in 100% mortality. The model allowed preliminary testing of xenogeneic hepatocyte transplantation as a potential therapy.

Generation of pro-and anti-inflammatory mediators after acetaminophen overdose in surviving and non-surviving patients

Acetaminophen (APAP) overdose causes liver injury in animals and humans. Although well-studied in animals, limited longitudinal data exist on cytokine release after APAP overdose in patients. The purpose of this study was to quantify concentrations of cytokines in APAP overdose patients to determine if early cytokine or complement measurements can distinguish between surviving and non-surviving patients. Plasma was obtained from healthy controls, APAP overdose patients with no increase in liver transaminases, and surviving and non-surviving APAP overdose patients with severe liver injury. Interleukin-10 (IL-10), and CC chemokine ligand-2 (CCL2, MCP-1) were substantially elevated in surviving and non-surviving patients, whereas IL-6 and CXC chemokine ligand-8 (CXCL8, IL-8) had early elevations in a subset of patients only with liver injury. Day 1 IL-10 and IL-6 levels, and Day 2 CCL2, levels correlated positively with survival. There was no significant increase in IL-1α, IL-1β or TNF-α in any patient during the first week after APAP. Monitoring cytokines such as CCL2 may be a good indicator of patient prognosis; furthermore, these data indicate the inflammatory response after APAP overdose in patients is not mediated by a second phase of inflammation driven by the inflammasome.

Challenges and Future of Drug-Induced Liver Injury Research-Laboratory Tests

Drug-induced liver injury (DILI) is a rare but potentially severe adverse drug event, which is also a major cause of study cessation and market withdrawal during drug development. Since no acknowledged diagnostic tests are available, DILI diagnosis poses a major challenge both in clinical practice as well as in pharmacovigilance. Differentiation from other liver diseases and the identification of the causative agent in the case of polymedication are the main issues that clinicians and drug developers face in this regard. Thus, efforts have been made to establish diagnostic testing methods and biomarkers in order to safely diagnose DILI and ensure a distinguishment from alternative liver pathologies. This review provides an overview of the diagnostic methods used in differential diagnosis, especially with regards to autoimmune hepatitis (AIH) and drug-induced autoimmune hepatitis (DI-AIH), in vitro causality methods using individual blood samples, biomarkers for diagnosis and severity prediction, as well as experimental predictive models utilized in pre-clinical settings during drug development regimes.

Systemic cytokine profiles in biliary atresia

Background

Inflammation and immune dysregulation persuade biliary duct injury in biliary atresia (BA), a leading cause of pediatric liver transplantation given lack of specific biomarkers. We aimed to determine associations between systemic cytokine profiles and clinical parameters in BA patients and to identify potential BA biomarkers.

Methods

Systemic levels of 27 cytokines were measured in 82 BA patients and 25 healthy controls using a multiplex immunoassay. Relative mRNA expressions of candidate cytokines in 20 BA livers and 5 non-BA livers were assessed using quantitative real-time PCR.

Results

Higher levels of 17 cytokines including IL-1β, IL-6, IL-7, IL-8, IL-9, IL-2, IL-15, eotaxin, IP-10, MCP-1, MIP-1α, MIP-1β, G-CSF, IL-1ra, IL-4, IL-5, and IL-10 and lower levels of IFN-α and PDGF were significantly associated with BA. In BA patients, increased levels of IL-7, eotaxin, IP-10, and IL-13 were significantly associated with unfavorable outcomes including jaundice, fibrosis, and portal hypertension. Indeed, systemic levels of those cytokines were significantly correlated with clinical parameters indicating jaundice, fibrosis, and hepatic dysfunction in BA patients. Out of 27 cytokines, 4 (IL-8, IP-10, MCP-1, and PDGF) had potential as sensitive and specific biomarkers of BA. Of these, higher IL-8 levels were significantly associated with reduced survival of BA. In BA livers, relative mRNA expressions of IL-8, IP-10, and MCP-1 were significantly up-regulated.

Conclusions

Higher levels of several cytokines including inflammatory cytokines, immunomodulatory cytokines, chemokines, and anti-inflammatory cytokines and lower levels of growth factors would reflect inflammatory and immune responses related to BA development. Among 27 cytokines, plasma IL-8 might have great potential as a diagnostic and prognostic biomarker for BA.

Referral system has a diminished difference in the risk for hepatic encephalopathy development among each etiology in patients with acute liver injury

AIM

Hepatic encephalopathy (HE) development is crucial in liver transplantation for patients with acute liver injury (ALI) and failure (ALF); to predict HE development, the Japan Hepatic Encephalopathy Prediction (JHEP) model, calculated using age, etiology, prothrombin time (PT), and total bilirubin, was established in 2004, and a referral system to the liver center was implemented using the JHEP model from April 2004.

METHODS

The JHEP model's ability to predict HE development in 460 consecutive patients with ALI between April 2004 and January 2021 using data from the referral system was evaluated, and the JHEP model was revised.

RESULTS

During the observation period, 7.8% patients developed HE. There was no difference in the proportion of HE development among the etiologies. In the Hosmer-Lemeshow test for HE development prediction, the JHEP model, revised JHEP (rJHEP) model, which was calculated without etiology data, and the modified JHEP model, which used the PT international ratio instead of PT in the rJHEP model, were good fitting models. Upon 30% random sampling from the total patients 60 times, the receiver operating curve analysis of both JHEP and rJHEP models for HE development was performed in all the datasets. The area under the curve of the JHEP model was subtracted from that of the rJHEP model (95% confidential interval, 0.000516-0.01793).

CONCLUSIONS

The referral system using the JHEP model reduced the difference in the risk for HE development among each etiology; the rJHEP model had a better prediction ability for HE development than the JHEP model.

Clinical correlation between serum cytokines and the susceptibility to Polygonum multiflorum-induced liver injury and an experimental study

Polygonum multiflorum (PM), a popular functional food, and a herbal and dietary supplement, is widely used as a tonic in China and East Asia. In recent years, it has attracted great concern for its ability to cause idiosyncratic drug-induced liver injury (IDILI). However, identifying individuals susceptible to IDILI remains challenging. This is a prospective study. For 6 patients whose serum alanine aminotransferase (ALT) levels after consuming PM were abnormally elevated (susceptible group), 15 patients with normal levels of liver injury markers were matched (tolerant group) based on similar baseline characteristics. ProcartaPlex immunoassays were adopted to quantitatively detect 33 serum cytokines in the two groups of patients before consuming PM, to characterize the cytokine profile and screen differential cytokines. Subsequently, the susceptibility of a potential biomarker to regulate PM-induced liver injury was validated in animal models. There were significant differences in the cytokine profiles between the susceptible and tolerant groups, wherein the susceptible patients showed immune perturbation characterized by high expression of multiple inflammatory cytokines, especially the proinflammatory cytokine TNF-α (P = 0.006). Among them, the cytokine TNF-α had the strongest correlation with ALT, where the correlation coefficient was greater than 0.6, and the area under the receiver operating characteristic curve was more than 0.8. Animal experiments revealed that both PM water extract and its susceptibility component of liver injury, cis-stilbene glucoside, could cause liver injury in the mice pre-stimulated using TNF-α. Conversely, administration of the same dose of drugs on control mice did not show any hepatotoxicity. In conclusion, immune perturbation mainly mediated by TNF-α may regulate the susceptibility to PM-induced liver injury. This provides a new perspective for the study of susceptibility to IDILI.

Kupffer cells regulate liver recovery through induction of chemokine receptor CXCR2 on hepatocytes after acetaminophen overdose in mice

Acetaminophen (APAP) is a widely used analgesic, but also a main cause of acute liver injury in the United States and many western countries. APAP hepatotoxicity is associated with a sterile inflammatory response as shown by the infiltration of neutrophils and monocytes. While the contribution of the immune cells to promote liver repair have been demonstrated, the direct interactions between macrophages or neutrophils with hepatocytes to help facilitate hepatocyte proliferation and tissue repair remain unclear. The purpose of this study was to investigate the relationship between resident macrophages (Kupffer cells) and hepatocytes with a focus on the chemokine receptor CXCR2. C57BL/6J mice were subjected to an APAP overdose (300 mg/kg) and the role of CXCR2 on hepatocytes was investigated using a selective antagonist, SB225002. In addition, clodronate liposomes were used to deplete Kupffer cells to assess changes in CXCR2 expression. Our data showed that CXCR2 was mainly expressed on hepatocytes and it was induced specifically in hepatocytes around the necrotic area 24 h after APAP treatment. Targeting this receptor using an inhibitor caused a delayed liver recovery. Depletion of Kupffer cells significantly prevented CXCR2 induction on hepatocytes. In vitro and in vivo experiments also demonstrated that Kupffer cells regulate CXCR2 expression and pro-regenerative gene expression in surviving hepatocytes through production of IL-10. Thus, Kupffer cells support the transition of hepatocytes around the area of necrosis to a proliferative state through CXCR2 expression.

Biomarkers of idiosyncratic drug-induced liver injury (DILI) - a systematic review

INTRODUCTION

Idiosyncratic drug-induced liver injury (DILI) is an unpredictable event, and there are no specific biomarkers that can distinguish DILI from alternative explanations or predict its clinical outcomes.

AREAS COVERED

This systematic review summarizes the available evidence for all biomarkers proposed to have a role in the diagnosis or prognosis of DILI. Following a comprehensive search, we included all types of studies in humans. We included DILI cases based on any threshold criteria but excluded intrinsic DILI, commonly caused by paracetamol overdose. We classified studies into diagnostic and prognostic categories and assessed their methodological quality. After reviewing the literature, 14 studies were eligible.

EXPERT OPINION

Diagnostic studies were heterogeneous with regard to the study population and outcomes measured. Prognostic models were developed by integrating novel biomarkers, risk scores, and traditional biomarkers, which increased their prognostic ability to predict death or transplantation by 6 months. This systematic review highlights the case of need for non-genetic biomarkers that distinguish DILI from acute liver injury related to alternative etiology. Biomarkers with the potential to identify serious adverse outcomes from acute DILI should be validated in independent prospective cohorts with a substantial number of cases.

APAP-induced IκBβ/NFκB signaling drives hepatic IL6 expression and associated sinusoidal dilation

Acetaminophen (APAP) overdose results in high morbidity and mortality, with limited treatment options. Increased understanding of the cellular signaling pathways activated in response to toxic APAP exposure is needed to provide insight into novel therapeutic strategies. Toxic APAP exposure induces hepatic nuclear factor kappa B (NFκB) activation. NFκB signaling has been identified to mediate the pro-inflammatory response, but also induces a pro-survival and regenerative response. It is currently unknown whether potentiating NFkB activation would be injurious or advantageous after APAP overdose. The NFκB inhibitory protein beta (IκBβ) dictates the duration and degree of the NFκB response following exposure to oxidative injuries. Thus, we sought to determine whether IκBβ/NFκB signaling contributes to APAP-induced hepatic injury. At late time points (24 hours) following toxic APAP exposures, mice expressing only IκBβ (AKBI mice) exhibited increased serologic evidence of hepatic injury. This corresponded with increased histologic injury, specifically related to sinusoidal dilatation. Compared to wild-type (WT) mice, AKBI mice demonstrated sustained hepatic nuclear translocation of the NFκB subunits p65 and p50, and enhanced NFκB target gene expression. This included increased expression of interleukin-6 (Il-6), a known contributor to hepatic sinusoidal dilation. This transcriptional response corresponded with increased plasma protein content of Il-6, as well as increased activation of signal transducer and activator of transcription 3 (STAT3). Impact Statement: IκBβ/NFκB signaling is associated with a pro-inflammatory response, exacerbated Il-6 and STAT3 activation, and this was associated with late development of sinusoidal dilatation. Thus, targeting sustained IκBβ/NFκB signaling may represent a novel therapeutic approach to attenuate late hepatic injury following toxic APAP exposure.

Potential Networks Regulated by MSCs in Acute-On-Chronic Liver Failure: Exosomal miRNAs and Intracellular Target Genes

Acute-on-chronic liver failure (ACLF) is a severe syndrome associated with high mortality. Alterations in the liver microenvironment are one of the vital causes of immune damage and liver dysfunction. Human bone marrow mesenchymal stem cells (hBMSCs) have been reported to alleviate liver injury via exosome-mediated signaling; of note, miRNAs are one of the most important cargoes in exosomes. Importantly, the miRNAs within exosomes in the hepatic microenvironment may mediate the mesenchymal stem cell (MSC)-derived regulation of liver function. This study investigated the hepatocyte exosomal miRNAs which are regulated by MSCs and the target genes which have potential in the treatment of liver failure. Briefly, ACLF was induced in mice using carbon tetrachloride and primary hepatocytes were isolated and co-cultured (or not) with MSCs under serum-free conditions. Exosomes were then collected, and the expression of exosomal miRNAs was assessed using next-generation sequencing; a comparison was performed between liver cells from healthy versus ACLF animals. Additionally, to identify the intracellular targets of exosomal miRNAs in humans, we focused on previously published data, i.e., microarray data and mass spectrometry data in liver samples from ACLF patients. The biological functions and signaling pathways associated with differentially expressed genes were predicted using gene ontology and Kyoto Encyclopedia of Genes and Genomics enrichment analyses; hub genes were also screened based on pathway analysis and the prediction of protein-protein interaction networks. Finally, we constructed the hub gene-miRNA network and performed correlation analysis and qPCR validation. Importantly, our data revealed that MSCs could regulate the miRNA content within exosomes in the hepatic microenvironment. MiR-20a-5p was down-regulated in ACLF hepatocytes and their exosomes, while the levels of chemokine C-X-C Motif Chemokine Ligand 8 (CXCL8; interleukin 8) were increased in hepatocytes. Importantly, co-culture with hBMSCs resulted in up-regulated expression of miR-20a-5p in exosomes and hepatocytes, and down-regulated expression of CXCL8 in hepatocytes. Altogether, our data suggest that the exosomal miR-20a-5p/intracellular CXCL8 axis may play an important role in the reduction of liver inflammation in ACLF in the context of MSC-based therapies and highlights CXCL8 as a potential target for alleviating liver injury.

Amphiregulin alleviated concanavalin A-induced acute liver injury via IL-22

OBJECTIVES

Amphiregulin (Areg), a glycoprotein from the epidermal growth factor receptor (EGFR) ligand family, has a well-documented protective role against tissue injury; however, its effects on immune-mediated liver injury are still unclear. Here, we used a concanavalin A (ConA)-induced acute liver hepatitis model to explore the effects of Areg on immune-mediated acute liver injury.

MATERIALS AND METHODS

Some C57BL/6 mice were administered ConA at a dose of 20 mg/kg (model mice), and some received 5 µg of Areg (treated mice). Then, their survival rates over 36 h were analyzed. After 5 h of treatment, liver function, hepatic histology, and apoptosis in liver tissue were investigated, and cytokine expression and neutrophil infiltration and activity in the liver were detected. Moreover, the protective effects of Areg were also evaluated without IL-22 in vivo.

RESULTS

Our results showed that Areg administration increased acute liver failure (ALF) mouse survival, restored liver function, and alleviated liver damage. Interestingly, Areg administration increased IL-22 production in hepatic T cells and upregulated IL-22 concentrations in the serum and liver, whereas IL-22 neutralization completely abolished the therapeutic effect of Areg. Meanwhile, Areg administration was concomitant with increased expression of the anti-apoptotic proteins Bcl-2 and Bcl-xL, which are important in the hepatoprotective mechanism of IL-22.

CONCLUSIONS

Areg showed direct protective effects against ConA-induced acute liver injury, which suggests the potential therapeutic application of Areg in immune-mediated ALF.

Drug-Induced Liver Injury: Biomarkers, Requirements, Candidates, and Validation

The hepatotoxicity of drugs is the main cause of drug withdrawal from the pharmaceutical market and interruption of the development of new molecules. Biomarkers are useful in several situations. In case of suspected drug-induced liver injury (DILI), biomarkers can be used to confirm liver damage, its severity, prognosis, confirm drug causality, or define the type of DILI. In this review, we will first present the currently used biomarkers and candidate biomarkers for the future. The current biomarkers are certainly very helpful including with the assistance of diagnostic method such the Roussel Uclaf Causality Assessment Method, but provide a limited information for the early detection of liver injury, the role of specific drug and the prediction of DILI. Some biomarkers are promising but they are not yet available for routine use. Studies are still needed to confirm their interest, particularly in comparison to Roussel Uclaf Causality Assessment Method.

Unfavorable prognosis of patients with acute liver injury due to drug-induced liver injury and acute exacerbation of hepatitis B virus infection

AIM

Acute liver injury (ALI) has a favorable prognosis, whereas acute liver failure (ALF) leads to organ failure and thus has an unfavorable prognosis. The effect of each etiology on the clinical course of ALI remains unclear. This study aimed to determine how each etiology and glucocorticoid on the unfavorable etiology affects the clinical course of ALI.

METHODS

This prospective observational study enrolled 522 patients with ALI/ALF from 2004 and 2017. To evaluate the influence of etiology on prognosis, decision tree analysis was carried out using age, disease type, etiology, and the presence of hepatic encephalopathy.

RESULTS

Of 522 patients, 398 patients satisfied the ALI criteria at registration in this study. The ALI etiologies were as follows: viral hepatitis through oral infection (n = 54), acute hepatitis B virus (HBV) infection (n = 24), acute exacerbation of HBV infection (n = 30), de novo hepatitis due to HBV (n = 5), autoimmune hepatitis (n = 59), drug-induced liver injury (DILI; n = 85), other viruses (n = 12), and undetermined (n = 129). ALI in 46 patients progressed to ALF after registration. Of 11 patients (age >52 years) with ALF due to acute exacerbation of HBV infection or DILI, seven patients (63.6%) died. Whether glucocorticoid affected the clinical course of ALI due to acute exacerbation of HBV infection or DILI was evaluated using propensity score matching (age, sex, alanine aminotransferase, total bilirubin, and prothrombin time-international normalized ratio). Glucocorticoid did not improve the prognosis of ALI patients due to the two etiologies.

CONCLUSIONS

Progression of ALI due to DILI or acute exacerbation of HBV infection to ALF showed a poor prognosis.

Old problem, new solutions: biomarker discovery for acetaminophen liver toxicity

Introduction: Although the hepatotoxicity of acetaminophen is a well-known problem, the search for reliable biomarker of toxicity is still a current issue as clinical tools are missing to assess patients intoxicated following chronic use, sequential ingestion, use of modified release formulations or in case of delayed arrival to hospital. The need for new specific and robust biomarkers for acetaminophen toxicity has prompted many studies exploring the use of blood levels of acetaminophen derivatives, mitochondrial damage markers, liver cell apoptosis and/or necrosis markers and circulating microRNAs. Areas covered: In this review, we present a concise overview of the most promising biomarkers currently under evaluation including descriptions of their properties with respect to exposure type, APAP specificity, and potential clinical application. In addition, we illustrate the power of new technologies for biomarker research and describe their current application to the field of acetaminophen-induced hepatotoxicity. Expert opinion: Recently the use of extracellular vesicles isolation in combination with omics techniques has opened a new perspective to the field of biomarker research. However, the potential of those new technologies for the prediction and monitoring of hepatic diseases and acetaminophen toxicity has not yet been fully taken into consideration.

Biomarkers of Drug-Induced Liver Toxicity

Drug-induced liver injury (DILI) is a comprehensive phenomenon. The injury to the liver may occur as an unexpected and undesired reaction to a therapeutic dose of a drug (idiosyncratic reaction) or as an expected therapeutic effect of the direct (intrinsic) toxicity of a drug taken in a large enough dose to cause liver injury. The direct toxicity (type A) reactions represent an extension of the drug's therapeutic effect; they occur relatively frequently and are typically dose-related and frequency-of-exposure-related. By contrast, idiosyncratic reactions, or type B reactions, are unpredictable, occurring only in susceptible individuals, and are unrelated to the dose or frequency of exposure. DILI encompasses both acute and/or chronic hepatic lesions. The liver injury may be the only clinical manifestation of the adverse drug effect. Otherwise, it may be accompanied by injury to other organs, or by systemic manifestations. The liver injury may be observed in 1-8 days from taking the drug. DILI cases may result in the disapproval of a new drug or in the removal of a useful drug from the market by regulatory agencies. The purpose of this review is to provide guidance to facilitate the detection and assessment of hepatotoxicity induced by therapeutics that received market authorization. This review supports the safe and effective use of drugs by patients and guides laboratory medicine professional in determining the possible drug-induced liver damage.

Metabolomics and Cytokine Analysis for Identification of Severe Drug-Induced Liver Injury

AIM

To evaluate the levels of metabolites and cytokines in the serum of patients with severe and non-severe idiosyncratic drug-induced liver injury (DILI) and to identify biomarkers of DILI severity.

METHODS

Gas chromatography-mass spectrometry (GC-MS) and ultraperformance liquid chromatography-mass spectrometry (UPLC-MS) based metabolomic approaches were used to evaluate the metabolome of serum samples from 29 DILI patients of severity grade 3 (non-severe), 27 of severity grade 4 (severe), and 36 healthy control (HC). The levels of total keratin-18 (K18), fragment K18, and 27 cytokines were determined by enzyme-linked immunosorbent assay.

RESULTS

The alkaline phosphatase activity ( p = 0.021) and international normalized ratio (INR) ( p < 0.001) differed significantly between the severe and non-severe groups. The severe group had a higher serum fragment K18 level than the non-severe group. A multivariate analysis showed good separation between all pairs of the HC, non-severe, and severe groups. According to the orthogonal partial least-squares-discriminant analysis (OPLS-DA) model, 14 metabolites were selected by GC-MS and 17 by UPLC-MS. Among these metabolites, the levels of 16 were increased and of 15 were decreased in the severe group. A pathway analysis revealed major changes in the primary bile acid biosynthesis and alpha-linolenic acid metabolic pathways. The levels of PDGF-bb, IP-10, IL-1Rα, MIP-1β, and TNF-α differed significantly between the severe and non-severe groups, and the levels of most of the metabolites were negatively correlated with those of these cytokines. An OPLS-DA model that included the detected metabolites and cytokines revealed clear separation of the severe and non-severe groups.

CONCLUSION

We identified 31 metabolites and 5 cytokines related to the severity of idiosyncratic DILI. The primary bile acid biosynthesis and alpha-linolenic acid metabolism pathways were also related to the severity of DILI. A model that incorporated the metabolites and cytokines showed clear separation between patients with severe and non-severe DILI, suggesting that these biomarkers have potential as indicators of DILI severity.

Idiosyncratic drug-induced liver injury in patients: Detection, severity assessment, and regulatory implications

Idiosyncratic Drug-Induced Liver Injury (IDILI) is a rare but potentially life-threatening event that is caused by drugs that, at usual therapeutic doses, do not cause any biochemical or clinical evidence of liver injury in the majority of treated patients. The most common clinical phenotypes of IDILI are "acute hepatitis," "mixed hepatocellular-cholestatic hepatitis," and "cholestatic hepatitis" and these are distinguished by clinical, biochemical and histologic characteristics. Anti-microbials, herbals and dietary supplements are now the agents most often implicated in the US Drug-Induced Liver Injury Network registry. There are several scales that have been used to characterize the severity of IDILI events. There are no reliable means to accurately predict the course of an IDILI event at presentation. In clinical trials, the "gold standard" liver safety signal is the occurrence of "Hy's Law Cases." Making the diagnosis of IDILI, and when a patient is taking multiple drugs, identifying the most likely culprit can be challenging, but many drugs cause IDILI with characteristic clinical and biochemical presentations, or "signatures." In a clinical trial, it is sometimes possible to identify an overlooked "signature" of IDILI by characterizing more minor, asymptomatic, and transient elevations in liver chemistries. This observation can be helpful in assessing causation in rare serious liver events occurring in the clinical trial, or first recognized post-marketing.

Biomarkers of drug-induced liver injury

Drug-induced liver injury (DILI) is a major clinical and regulatory challenge. As a result, interest in DILI biomarkers is growing. So far, considerable progress has been made in identification of biomarkers for diagnosis (acetaminophen-cysteine protein adducts), prediction (genetic biomarkers), and prognosis (microRNA-122, high mobility group box 1 protein, keratin-18, glutamate dehydrogenase, mitochondrial DNA). Many of those biomarkers also provide mechanistic insight. The purpose of this chapter is to review major advances in DILI biomarker research over the last decade, and to highlight some of the challenges involved in implementation. Although much work has been done, more liver-specific biomarkers, more DILI-specific biomarkers, and better prognostic biomarkers for survival are all still needed. Furthermore, more work is needed to define reference intervals and medical decision limits.