The Role of Hypoxia-Inducible Factor 1 Alpha in Acute-on-Chronic Liver Failure.

Acute-on-chronic liver failure (ACLF) is associated with increased mortality. Specific therapy options are limited. Hypoxia-inducible factor 1 alpha (HIF-1α) has been linked to the pathogenesis of chronic liver disease (CLD), but the role of HIF-1α in ACLF is poorly understood. In the current study, different etiologies of CLD and precipitating events triggering ACLF were used in four rodent models. HIF-1α expression and the intracellular pathway of HIF-1α induction were investigated using real-time quantitative PCR. The results were verified by Western blotting and immunohistochemistry for extrahepatic HIF-1α expression using transcriptome analysis. Exploratory immunohistochemical staining was performed to assess HIF-1α in human liver tissue. Intrahepatic HIF-1α expression was significantly increased in all animals with ACLF, regardless of the underlying etiology of CLD or the precipitating event. The induction of HIF-1α was accompanied by the increased mRNA expression of NFkB1 and STAT3 and resulted in a marked elevation of mRNA levels of its downstream genes. Extrahepatic HIF-1α expression was not elevated. In human liver tissue samples, HIF-1α expression was elevated in CLD and ACLF. Increased intrahepatic HIF-1α expression seems to play an important role in the pathogenesis of ACLF, and future studies are pending to investigate the role of therapeutic HIF inhibitors in ACLF.

PANoptosis-like death in acute-on-chronic liver failure injury.

The pathogenesis of Acute-on-chronic liver failure (ACLF) involves several forms of cell death, such as pyroptosis, apoptosis, and necroptosis, which consist of PANoptosis. To explore PANoptosis as a regulated cell death pathway in ACLF. Firstly, a bioinformatic strategy was used to observe the role of the PANoptosis pathway in ACLF and identify differentially expressed genes related to PANoptosis. Enrichment analysis showed that PANoptosis-related pathways were up-regulated in ACLF. We screened out BAX from the intersection of pyroptosis, apoptosis, necroptosis, and DEGs. Secondly, we screened articles from literature databases related to PANoptosis and liver failure, and specific forms of PANoptosis were reported in different experimental models in vitro and in vivo. Secondly, we established a model of ACLF using carbon tetrachloride-induced liver fibrosis, followed by D-galactosamine and lipopolysaccharide joint acute attacks. A substantial release of inflammatory factors(IL-6, IL-18, TNFα, and IFNγ) and the key proteins of PANoptosis (NLRP3, CASP1, GSDMD, BAX, CASP8, CASP3, CASP7, and MLKL) were detected independently in the ACLF rats. Finally, we found that combining TNF-α/INF-γ inflammatory cytokines could induce L02 cells PANoptosis. Our study highlighted the potential role of ACLF and helps drug discovery targeting PANoptosis in the future.

Comparative analysis of monocyte-derived dendritic cell phenotype and T cell stimulatory function in patients with acute-on-chronic liver failure with different clinical parameters.

Background: Acute-on-Chronic Liver Failure (ACLF) patients experience systemic inflammation as well as immune dysfunction and exhaustion. The phenotype and functionality of monocyte-derived dendritic cells in ACLF patients with different clinical parameters have not been elucidated. Methods: This study included 37 cases of ACLF, 20 cases of Chronic Hepatitis B (CHB) patients, and 12 healthy controls. Demographic and laboratory parameters were collected from the enrolled patients. Peripheral blood samples were obtained from the participants. Monocyte-derived dendritic cells were induced and cultured, followed by co-culturing with T cells from the patients. Cell surface markers and intracellular markers were analyzed using flow cytometry. The relationship between these markers and clinical parameters was compared. Results: Our study found that ACLF patients had lower expression levels of HLA-DR, CD86, and CD54 on monocyte-derived dendritic cells compared to both CHB patients and healthy controls. IL-4, GM-CSF, and alcohol were found to promote the expression of HLA-DR, CD86, and CD54 on monocyte-derived dendritic cells. In ACLF patients, higher levels of procalcitonin (PCT), lower levels of albumin, decreased prothrombin activity and deceased patients were associated with lower expression of HLA-DR, CD86, and CD54 on monocyte-derived dendritic cells. Peripheral blood mononuclear cells (PBMCs), after removing adherent cells, were co-cultured with monocyte-derived DC. Our study revealed that patients with infection and low albumin levels exhibited a decreased proportion of T cell subsets within PBMCs. Additionally, these patients' T cells showed lower levels of Ki-67 and interferon-gamma (IFN-γ) production. Conclusion: ACLF patients exhibit varying clinical states, with differences in the phenotype and the ability of monocyte-derived dendritic cells to stimulate T cells. Alcohol can stimulate the maturation of monocyte-derived dendritic cells.

Resolvin D1 promotes the resolution of inflammation in the ACLF rat model by increasing the proportion of Treg cells.

OBJECTIVE: Acute-on-chronic liver failure (ACLF) causes organ system failures in patients and increases the risk of mortality. One of the main predictors of ACLF development in patients is the severity of systemic inflammation. The purpose of this study was to explore the effects of resolvin D1 (RvD1) on the rat model of ACLF. METHODS: The ACLF rats were induced by first intraperitoneally (ip) injecting CCl4 and porcine serum for 6 weeks to establish the chronic liver injury, followed by once administration (ip) of lipopolysaccharide and d-galactose d-GalN to cause acute liver injury (ALI). An hour before the ALI-induced treatment, rats were administrated (ip) with 0.9% saline or different doses of RvD1 (0.3 or 1 µg/kg). Afterward, the control and treated rats were killed and samples were collected. Biochemical analysis, hematoxylin-eosin and Sirius red staining, flow cytometry assay, and real-time polymerase chain reaction were used to assess the rat liver histopathological injury, the percentage of Treg cells in the spleen, and the messenger RNA (mRNA) levels of transcription factors and immunologic cytokines in liver. RESULTS: The necroinflammatory scores and the serum levels of transaminase significantly increased in ACLF rats compared with those in control rats. These impaired changes observed in ACLF rats could be attenuated by the administration of a low dose of RvD1 before the induction of ALI, which was associated with the increased proportion of regulatory T cells (Treg) in the spleen together with the increased gene expression ratio of Foxp3/RORγt and decreased mRNA level of Il-17a and Il-6 in the liver. CONCLUSION: A low dose of RvD1 can promote the resolution of inflammation in ACLF rats by increasing the proportion of Treg cells. RvD1, therefore, may be used as a potential drug for the treatment of patients with ACLF.

Mesenchymal stem cell-regulated miRNA-mRNA landscape in acute-on-chronic liver failure.

BACKGROUND: Acute-on-chronic liver failure (ACLF) is a major challenge in the field of hepatology. While mesenchymal stem cell (MSC) therapy can improve the prognosis of patients with ACLF, the molecular mechanisms through which MSCs attenuate ACLF remain poorly understood. We performed global miRNA and mRNA expression profiling via next-generation sequencing of liver tissues from MSC-treated ACLF mice to identify important signaling pathways and major factors implicated in ACLF alleviation by MSCs. METHODS: Carbon tetrachloride-induced ACLF mice were treated with saline or mouse bone marrow-derived MSCs. Mouse livers were subjected to miRNA and mRNA sequencing. Related signal transduction pathways were obtained through Gene Set Enrichment Analysis. Functional enrichment, protein-protein interaction, and immune infiltration analyses were performed for the differentially expressed miRNA target genes (DETs). Hub miRNA and mRNA associated with liver injury were analyzed using LASSO regression. The expression levels of hub genes were subjected to Pearson's correlation analysis and verified using RT-qPCR. The biological functions of hub genes were verified in vitro. RESULTS: The tricarboxylic acid cycle and peroxisome proliferator-activated receptor pathways were activated in the MSC-treated groups. The proportions of liver-infiltrating NK resting cells, M2 macrophages, follicular helper T cells, and other immune cells were altered after MSC treatment. The expression levels of six miRNAs and 10 transcripts correlated with the degree of liver injury. miR-27a-5p was downregulated in the mouse liver after MSC treatment, while its target gene E2f2 was upregulated. miR-27a-5p inhibited E2F2 expression, suppressed G1/S phase transition and proliferation of hepatocytes, in addition to promoting their apoptosis. CONCLUSIONS: This is the first comprehensive analysis of miRNA and mRNA expression in the liver tissue of ACLF mice after MSC treatment. The results revealed global changes in hepatic pathways and immune subpopulations. The miR-27a-5p/E2F2 axis emerged as a central regulator of the MSC-induced attenuation of ACLF. The current findings improve our understanding of the molecular mechanisms through which MSCs alleviate ACLF.

Mesenchymal Stem Cells Promote Polarization of M2 Macrophages in Mice with Acute-On-Chronic Liver Failure via Mertk/JAK1/STAT6 Signaling.

Acute-on-chronic liver failure (ACLF) is a severe disease with a high mortality. Macrophage-related inflammation plays a crucial role in ACLF development. Mesenchymal stem cells (MSCs) treatment was demonstrated to be beneficial in ACLF in our previous study; however, the underlying mechanisms remain unknown. Therefore, mouse bone marrow-derived MSCs were used to treat an ACLF mouse model or cocultured with RAW264.7/J774A.1 macrophages that were stimulated with LPS. Histological and serological parameters and survival were analyzed to evaluate efficacy. We detected changes of Mer tyrosine kinase (Mertk), JAK1/STAT6, inflammatory cytokines, and markers of macrophage polarization in vitro and in vivo. In ACLF mice, MSCs improved liver function and 48-h survival of ACLF mice and alleviated inflammatory injury by promoting M2 macrophage polarization and elevated Mertk expression levels in macrophages. This is significant, as Mertk regulates M2 macrophage polarization via the JAK1/STAT6 signaling pathway.

Yi-Qi-Jian-Pi formula inhibits hepatocyte pyroptosis through the IDH2-driven tricarboxylic acid cycle to reduce liver injury in acute-on-chronic liver failure.

ETHNOPHARMACOLOGICAL RELEVANCE: Yi-Qi-Jian-Pi formula (YQJPF) is a commonly used traditional Chinese medicine (TCM) compound used to treat acute-on-chronic liver failure (ACLF) in China, but its specific mechanism of action has not been fully clarified. AIM OF THE STUDY: The aim of this study was to determine the effect of YQJPF on liver injury and hepatocyte pyroptosis in rats and further explore its molecular mechanism of action. MATERIALS AND METHODS: This study established carbon tetrachloride (CCl4)-, lipopolysaccharide (LPS)- and D-galactose (D-Gal)-induced in vivo models of ACLF in rats and in vitro LPS-induced hepatocyte injury models. Animal experiments were divided into the following groups: control, ACLF model, groups with different doses of YQJPF (5.4, 10.8, and 21.6 g/kg), and western medicine (methylprednisolone). There were 7 rats in the control group and 11 in the other groups. Serological, immunohistochemical, and pathological analyses were used to observe the effect of YQJPF on the liver of ACLF rats. The protective effect of YQJPF on hepatocytes was further verified by RT-qPCR, western blotting, flow cytometry, enzyme-linked immunosorbent assay (ELISA), and other methods. RESULTS: YQJPF significantly improved liver injury in vivo and in vitro, which depended on the regulation of hepatocyte NLRP3/GSDMD-induced pyroptosis. In addition, we found that mitochondrial membrane potential and ATP production decreased after LPS treatment of hepatocytes, which suggested that YQJPF may improve mitochondrial energy metabolism disorders in hepatocytes. We administered a hepatocyte mitochondrial uncoupling agent, FCCP, to determine whether mitochondrial metabolic disorders affected cell pyroptosis. The results showed that the expression of IL-18, IL-1ß, and NLRP3 proteins increased significantly, indicating that the effect of this drug on hepatocyte pyroptosis may be related to mitochondrial metabolism disorders. We found that YQJPF significantly restored the tricarboxylic acid (TCA) cycle rate-limiting enzyme activity and affected the content of TCA metabolites. Furthermore, we revealed that the IDH2 gene, which plays a unique role in ACLF, is a key factor in the regulation of the mitochondrial TCA cycle and can be upregulated under the action of YQJPF. CONCLUSIONS: YQJPF can inhibit classical pyroptosis in hepatocytes by regulating TCA cycle metabolism, thus alleviating liver injury, and IDH2 may be a potential upstream regulatory target of YQJPF.

IGF2BP3/HIF1A/YAP signaling plays a role in driving acute-on-chronic liver failure through activating hepatocyte reprogramming.

BACKGROUND: Acute-on-chronic liver failure (ACLF) is a syndrome with both high prevalence and mortality. However, the underlying mechanisms remain elusive and there is no effective therapeutic approach available. Here we aim to uncover novel molecular mechanisms of ACLF and identify potential therapeutic targets. METHOD: We performed integrative analysis of 3 transcriptomic datasets and subsequent bioinformatic analysis aiming for potential genes of significance in ACLF development, identifying a critical role of IGF2BP3/HIF1A signaling in development of ACLF. Expression of molecules in IGF2BP3/HIF1A pathway and hepatocyte reprogramming markers in clinical samples were then determined by western blot and quantitative PCR. N6-methyladenosine (m6A) RNA modification of HIF1A was analyzed by m6A dot assay and PCR following m6A-antibody precipitation. The molecular mechanisms among IGFBP3, HIF1α and YAP1 were further validated by gene overexpression and knockdown experiments in HepG2 and Hep3B cells. Cell phenotypes of hepatocyte reprogramming were determined by EdU staining, sphere formation assay and immunoblotting of relevant markers. RESULTS: Our data demonstrated that IGF2BP3 recognized m6A modification in HIF1A mRNA as an m6A reader, thereby promoting expression of HIF1A by increasing RNA stability. HIF1A activated Rho GTPases (RhoA) and suppressed phosphorylation of YAP via inhibiting LATS1/2, promoting translocation of non-phosphorylated YAP into the nucleus, resulting in fetal liver programme and ultimate hepatic injury in ACLF patients. CONCLUSION: We reveal a novel molecular mechanism that IGF2BP3/HIF1A/YAP signaling promotes hepatocyte reprogramming, causing hepatic injury in ACLF. Our study provides potential targets for treatment of ACLF.

Mesenchymal stem cells exosomal let-7a-5p improve autophagic flux and alleviate liver injury in acute-on-chronic liver failure by promoting nuclear expression of TFEB.

Acute-on-chronic liver failure is a distinct clinical syndrome characterized by a dysregulated immune response and extensive hepatocyte death without satisfactory therapies. As a cytoplasmic degradative and quality-control process, autophagy was implicated in maintaining intracellular homeostasis, and decreased hepatic autophagy was found in many liver diseases and contributes to disease pathogenesis. Previously, we identified the therapeutic potential of mesenchymal stem cells (MSCs) in ACLF patients; however, the intrinsic mechanisms are incompletely understood. Herein, we showed that MSCs restored the impaired autophagic flux and alleviated liver injuries in ACLF mice, but these effects were abolished when autophago-lysosomal maturation was inhibited by leupeptin (leu), suggesting that MSCs exerted their hepatoprotective function in a pro-autophagic dependent manner. Moreover, we described a connection between transcription factor EB (TFEB) and autophagic activity in this context, as evidenced by increased nuclei translocation of TFEB elicited by MSCs were capable of promoting liver autophagy. Mechanistically, we confirmed that let-7a-5p enriched in MSCs derived exosomes (MSC-Exo) could activate autophagy by targeting MAP4K3 to reduce TFEB phosphorylation, and MAP4K3 knockdown partially attenuates the effect of anti-let-7a-5p oligonucleotide via decreasing the inflammatory response, in addition, inducing autophagy. Altogether, these findings revealed that the hepatoprotective effect of MSCs may partially profit from its exosomal let-7a-5p mediating autophagy repairment, which may provide new insights for the therapeutic target of ACLF treatment.

Galectin-3 critically mediates the hepatoprotection conferred by M2-like macrophages in ACLF by inhibiting pyroptosis but not necroptosis signalling.

We previously documented that M2-like macrophages exert a hepatoprotective effect in acute-on-chronic liver failure (ACLF) by inhibiting necroptosis signalling. Nevertheless, the molecular mechanism behind this hepatoprotection still needs to be further dissected. Galectin-3 (GAL3) has been reported to be critically involved in the pathogenesis of multiple liver diseases, whereas the potential role of GAL3 in ACLF remains to be explored. Herein, we hypothesised that GAL3 plays a pivotal role in the hepatoprotection conferred by M2-like macrophages in ACLF by inhibiting necroptosis. To test this hypothesis, we first assessed the expression of GAL3 in control and fibrotic mice with or without acute insult. Second, loss- and gain-of-function experiments of GAL3 were performed. Third, the correlation between GAL3 and M2-like macrophage activation was analysed, and the potential role of GAL3 in M2-like macrophage-conferred hepatoprotection was confirmed. Finally, the molecular mechanism underlying GAL3-mediated hepatoprotection was dissected. GAL3 was found to be obviously upregulated in fibrotic mice with or without acute insult but not in acutely injured mice. Depletion of GAL3 aggravated hepatic damage in fibrotic mice upon insult. Conversely, adoptive transfer of GAL3 provided normal mice enhanced resistance against acute insult. The expression of GAL3 is closely correlated with M2-like macrophage activation. Through adoptive transfer and depletion experiments, M2-like macrophages were verified to act as a major source of GAL3. Importantly, GAL3 was confirmed to hold a pivotal place in the hepatoprotection conferred by M2-like macrophages through loss- and gain-of-function experiments. Unexpectedly, the depletion and adoptive transfer of GAL3 resulted in significant differences in the expression levels of pyroptosis but not necroptosis signalling molecules. Taken together, GAL3 plays a pivotal role in the hepatoprotection conferred by M2-like macrophages in ACLF by inhibiting pyroptosis but not necroptosis signalling. Our findings provide novel insights into the pathogenesis and therapy of ACLF.

Mitochondrial dysfunction governs immunometabolism in leukocytes of patients with acute-on-chronic liver failure.

BACKGROUND & AIMS: Patients with acute-on-chronic liver failure (ACLF) present a systemic hyperinflammatory response associated with increased circulating levels of small-molecule metabolites. To investigate whether these alterations reflect inadequate cell energy output, we assessed mitochondrial morphology and central metabolic pathways with emphasis on the tricarboxylic acid (TCA) cycle in peripheral leukocytes from patients with acutely decompensated (AD) cirrhosis, with and without ACLF. METHODS: The study included samples from patients with AD cirrhosis (108 without and 128 with ACLF) and 41 healthy individuals. Leukocyte mitochondrial ultrastructure was visualized by transmission electron microscopy and cytosolic and mitochondrial metabolic fluxes were determined by assessing NADH/FADH2 production from various substrates. Plasma GDF15 and FGF21 were determined by Luminex and acylcarnitines by LC-MS/MS. Gene expression was analyzed by RNA-sequencing and PCR-based glucose metabolism profiler array. RESULTS: Mitochondrial ultrastructure in patients with advanced cirrhosis was distinguished by cristae rarefication and swelling. The number of mitochondria per leukocyte was higher in patients, accompanied by a reduction in their size. Increased FGF21 and C6:0- and C8:0-carnitine predicted mortality whereas GDF15 strongly correlated with a gene set signature related to leukocyte activation. Metabolic flux analyses revealed increased energy production in mononuclear leukocytes from patients with preferential involvement of extra-mitochondrial pathways, supported by upregulated expression of genes encoding enzymes of the glycolytic and pentose phosphate pathways. In patients with ACLF, mitochondrial function analysis uncovered break-points in the TCA cycle at the isocitrate dehydrogenase and succinate dehydrogenase level, which were bridged by anaplerotic reactions involving glutaminolysis and nucleoside metabolism. CONCLUSIONS: Our findings provide evidence at the cellular, organelle and biochemical levels that severe mitochondrial dysfunction governs immunometabolism in leukocytes from patients with AD cirrhosis and ACLF. LAY SUMMARY: Patients at advanced stages of liver disease have dismal prognosis due to vital organ failures and the lack of treatment options. In this study, we report that the functioning of mitochondria, which are known as the cell powerhouse, is severely impaired in leukocytes of these patients, probably as a consequence of intense inflammation. Mitochondrial dysfunction is therefore a hallmark of advanced liver disease.

METTL3 inhibition ameliorates liver damage in mouse with hepatitis B virus-associated acute-on-chronic liver failure by regulating miR-146a-5p maturation.

Hepatitis B virus (HBV)-associated acute-on-chronic liver failure (ACLF) is a clinical syndrome of severe liver damage. HBV infection is affected by N6-methyladenosine (m6A) RNA modification. Here, we investigated whether methyltransferase-like 3 (METTL3)-mediated m6A methylation can affect ACLF. Human hepatic cells (THLE-2) were treated with lipopolysaccharide (LPS) to induce cell damage. Proliferation, apoptosis and m6A modification were measured by MTT assay, flow cytometry and Dot blot assay. Our results showed that HBV infection significantly enhanced the levels of m6A modification and elevated the expression of METTL3 and mature-miR-146a-5p in THLE-2 cells, which was repressed by cycloleucine (m6A inhibitor). METTL3 overexpression enhanced m6A modification and promoted mature-miR-146a-5p expression. METTL3 overexpression promoted HBV replication and apoptosis, enhanced the levels of pro-inflammatory cytokines, hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg), and repressed cell proliferation in THLE-2 cells, which attributed to repress miR-146a-5p maturation. Moreover, a severe liver failure mouse model was established by HBV infection to verify the impact of METTL3 knockdown on liver damage in vivo. HBV-infection led to a severe liver damage and increase of apoptosis in hepatic tissues of mice, which was abolished by METTL3 knockdown. METTL3 knockdown reduced METTL3 expression and impeded miR-146a-5p maturation in HBV-infected mice. In conclusion, this work demonstrates that METTL3 inhibition ameliorates liver damage in mouse with HBV-associated ACLF, which contributes to repress miR-146a-5p maturation. Thus, this article suggests a novel therapeutic avenue to prevent and treat HBV-associated ACLF.

Transcriptomics reveals immune-metabolism disorder in acute-on-chronic liver failure in rats.

Acute-on-chronic liver failure (ACLF) is clinical syndrome with high mortality rate. This study aimed to perform detailed transcriptomic analysis in liver cirrhosis-based ACLF rats to elucidate ACLF pathogenesis. ACLF was induced by combined porcine serum with D-galactosamine and lipopolysaccharide. Gene expression profile of liver tissues from ACLF rats was generated by transcriptome sequencing to reveal the molecular mechanism. ACLF rats successfully developed with typical characteristics. Total of 2,354/3,576 differentially expressed genes were identified when ACLF was compared to liver cirrhosis and normal control, separately. The functional synergy analysis revealed prominent immune dysregulation at ACLF stage, whereas metabolic disruption was significantly down-regulated. Relative proportions of innate immune-related cells showed significant elevation of monocytes and macrophages, whereas adaptive immune-related cells were reduced. The seven differentially expressed genes underlying the ACLF molecular mechanisms were externally validated, among them THBS1, IL-10, and NR4A3 expressions were confirmed in rats, patient transcriptomics, and liver biopsies, verifying their potential value in the ACLF pathogenesis. This study indicates immune-metabolism disorder in ACLF rats, which may provide clinicians new targets for improving intervention strategies.

Detoxification II Prescription Suppresses the Th-17/IL-17 Inflammatory Axis to Improve the Liver Function of ACLF-Rats via Inactivating the P38MAPK Pathway.

Hepatitis is a metabolic system disease which is a serious challenge to the medical and healthcare system of the world. This study attempted to investigate the therapeutic effect and illustrate the regulation pharmacological mechanism of Detoxification II Prescription on ACLF. In this study, the rats were injected with D-galactosamine to establish ACLF-rat models, and the levels of cholinesterase (CHE), alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin (ALB), and total bilirubin (TBiL) were measured with the related kits to reflect the liver functions of the rats. The levels of IL-17, IL-6, and IFN-γ in the serums of the rats were detected by qRT-PCR, and the percentages of Th-17 cells in CD4+ cells of the rats were measured by flow cytometry assay. In the results, the increased ALT, AST, TBiL, IL-6, IL-17, IFN-γ, and percentage of Th-17 cells in CD4+ and decreased ALB and CHE were found in the serums of the ACLF-rats, while Detoxification II Prescription could partly reverse those indexes of the ACLF-rats. Moreover, it was also found that Detoxification II Prescription could inhibit the expression of P38MAPK, and P38MAPK downregulation obviously improved the liver function indexes of the ACLF-rats including the levels of ALT, AST, TBiL, IL-6, IL-17, IFN-γ, and percentage of Th-17 cells in CD4+ cells. In conclusion, this study suggested that Detoxification II Prescription could suppress the Th-17/IL-17 inflammatory axis to improve the liver function of ACLF-rats via inhibiting the activity of the P38MAPK pathway.

Inflammatory signature in acute-on-chronic liver failure includes increased expression of granulocyte genes ELANE, MPO and CD177.

Acute-on-Chronic Liver Failure (ACLF) is associated with innate immune dysfunction and high short-term mortality. Neutrophils have been identified to influence prognosis in ACLF. Neutrophil biology is under-evaluated in ACLF. Therefore, we investigated neutrophil-specific genes and their association with ACLF outcomes. This is an observational study. Enriched granulocytes, containing neutrophils, isolated from study participants in three groups- ACLF(n = 10), chronic liver disease (CLD, n = 4) and healthy controls (HC, n = 4), were analysed by microarray. Differentially expressed genes were identified and validated by qRT-PCR in an independent cohort of ACLF, CLD and HC (n = 30, 15 and 15 respectively). The association of confirmed overexpressed genes with ACLF 28-day non-survivors was investigated. The protein expression of selected neutrophil genes was confirmed using flow cytometry and IHC. Differential gene expression analysis showed 1140 downregulated and 928 upregulated genes for ACLF versus CLD and 2086 downregulated and 1091 upregulated genes for ACLF versus HC. Significant upregulation of neutrophilic inflammatory signatures were found in ACLF compared to CLD and HC. Neutrophil enriched genes ELANE, MPO and CD177 were highly upregulated in ACLF and their expression was higher in ACLF 28-day non-survivors. Elevated expression of CD177 protein on neutrophil surface in ACLF was confirmed by flow cytometry. IHC analysis in archival post mortem liver biopsies showed the presence of CD177+ neutrophils in the liver tissue of ACLF patients. Granulocyte genes ELANE, MPO and CD177 are highly overexpressed in ACLF neutrophils as compared to CLD or HC. Further, this three-gene signature is highly overexpressed in ACLF 28-day non-survivors.

Fibroblast Growth Factor 21 Response in a Preclinical Alcohol Model of Acute-on-Chronic Liver Injury.

BACKGROUND AND AIMS: Fibroblast growth factor (FGF) 21 has recently been shown to play a potential role in bile acid metabolism. We aimed to investigate the FGF21 response in an ethanol-induced acute-on-chronic liver injury (ACLI) model in Abcb4-/- mice with deficiency of the hepatobiliary phospholipid transporter. METHODS: Total RNA was extracted from wild-type (WT, C57BL/6J) and Abcb4-/- (KO) mice, which were either fed a control diet (WT-Cont and KO-Cont groups; n = 28/group) or ethanol diet, followed by an acute ethanol binge (WT-EtOH and KO-EtOH groups; n = 28/group). A total of 58 human subjects were recruited into the study, including patients with alcohol-associated liver disease (AALD; n = 31) and healthy controls (n = 27). The hepatic and ileal expressions of genes involved in bile acid metabolism, plasma FGF levels, and bile acid and its precursors 7α- and 27-hydroxycholesterol (7α- and 27-OHC) concentrations were determined. Primary mouse hepatocytes were isolated for cell culture experiments. RESULTS: Alcohol feeding significantly induced plasma FGF21 and decreased hepatic Cyp7a1 levels. Hepatic expression levels of Fibroblast growth factor receptor 1 (Fgfr1), Fgfr4, Farnesoid X-activated receptor (Fxr), and Small heterodimer partner (Shp) and plasma FGF15/FGF19 levels did not differ with alcohol challenge. Exogenous FGF21 treatment suppressed Cyp7a1 in a dose-dependent manner in vitro. AALD patients showed markedly higher FGF21 and lower 7α-OHC plasma levels while FGF19 did not differ. CONCLUSIONS: The simultaneous upregulation of FGF21 and downregulation of Cyp7a1 expressions upon chronic plus binge alcohol feeding together with the invariant plasma FGF15 and hepatic Shp and Fxr levels suggest the presence of a direct regulatory mechanism of FGF21 on bile acid homeostasis through inhibition of CYP7A1 by an FGF15-independent pathway in this ACLI model. Lay Summary: Alcohol challenge results in the upregulation of FGF21 and repression of Cyp7a1 expressions while circulating FGF15 and hepatic Shp and Fxr levels remain constant both in healthy and pre-injured livers, suggesting the presence of an alternative FGF15-independent regulatory mechanism of FGF21 on bile acid homeostasis through the inhibition of Cyp7a1.

Dysregulation of the Lysophosphatidylcholine/Autotaxin/Lysophosphatidic Acid Axis in Acute-on-Chronic Liver Failure Is Associated With Mortality and Systemic Inflammation by Lysophosphatidic Acid-Dependent Monocyte Activation.

BACKGROUND & AIMS: Acute-on-chronic liver failure (ACLF) is characterized by systemic inflammation, monocyte dysfunction, and susceptibility to infection. Lysophosphatidylcholines (LPCs) are immune-active lipids whose metabolic regulation and effect on monocyte function in ACLF is open for study. APPROACHES & RESULTS: Three hundred forty-two subjects were recruited and characterized for blood lipid, cytokines, phospholipase (PLA), and autotaxin (ATX) concentration. Peripheral blood mononuclear cells and CD14+ monocytes were cultured with LPC, or its autotaxin (ATX)-derived product, lysophosphatidic acid (LPA), with or without lipopolysaccharide stimulation and assessed for surface marker phenotype, cytokines production, ATX and LPA-receptor expression, and phagocytosis. Hepatic ATX expression was determined by immunohistochemistry. Healthy volunteers and patients with sepsis or acute liver failure served as controls. ACLF serum was depleted in LPCs with up-regulated LPA levels. Patients who died had lower LPC levels than survivors (area under the receiver operating characteristic curve, 0.94; P < 0.001). Patients with high-grade ACLF had the lowest LPC concentrations and these rose over the first 3 days of admission. ATX concentrations were higher in patients with AD and ACLF and correlated with Model for End-Stage Liver Disease, Consortium on Chronic Liver Failure-Sequential Organ Failure Assessment, and LPC/LPA concentrations. Reduction in LPC correlated with higher monocyte Mer-tyrosine-kinase (MerTK) and CD163 expression. Plasma ATX concentrations rose dynamically during ACLF evolution, correlating with IL-6 and TNF-α, and were associated with increased hepatocyte ATX expression. ACLF patients had lower human leukocyte antigen-DR isotype and higher CD163/MerTK monocyte expression than controls; both CD163/MerTK expression levels were reduced in ACLF ex vivo following LPA, but not LPC, treatment. LPA induced up-regulation of proinflammatory cytokines by CD14+ cells without increasing phagocytic capacity. CONCLUSIONS: ATX up-regulation in ACLF promotes LPA production from LPC. LPA suppresses MerTK/CD163 expression and increases monocyte proinflammatory cytokine production. This metabolic pathway could be investigated to therapeutically reprogram monocytes in ACLF.

Circulating Neutrophil Dysfunction in HBV-Related Acute-on-Chronic Liver Failure.

Background and Aims: Acute-on-chronic liver failure (ACLF) is characterized by systemic inflammation accompanied by defective anti-bacterial immunity. The role of neutrophils in immune derangement of ACLF has not been fully elucidated. This study is aimed to characterize the role of circulating neutrophils in HBV-related ACLF patients. Methods: Quantitative, phenotypic, transcriptomic, and functional alterations of circulating neutrophils were compared in ACLF and non-ACLF subjects and analyzed for associations with short-term outcomes. Interventional experiments were performed to test the impact on ACLF-patient neutrophil function in vitro. Results: Circulating absolute neutrophil count was significantly increased in patients with ACLF and was an independent risk factor for 28-day mortality. ACLF-patient neutrophils differentially expressed a panel of surface markers (include TLR-1, TLR-2, TLR-4, CEACAM-1 and FPR1), as well as a distinct transcriptomic signature. ACLF-neutrophils displayed significantly impaired phagocytosis but an increased capacity to form neutrophil extracellular traps (NETs), which was more pronounced in patients with poor outcome. Healthy neutrophils mimicked functional characteristics of ACLF counterpart after co-cultured with plasma from ACLF patients. The oxidative burst and cytokine production capacities remained unchanged. Plasma GM-CSF, IL-6, IL-8, IL-10, and IP-10 levels, as well as lipopolysaccharide (LPS) concentration, were markedly elevated in ACLF patients but not DAMP molecules HMGB-1 and HSP70. Finally, a glycolysis inhibitor, 2-deoxy-glucose, reduced NET formation of ACLF patients' neutrophils. Conclusions: Circulating ACLF-patient neutrophils exhibit alterations in number, phenotype, gene expression and function, which was associated with poor outcome and shaped by the ACLF circulatory environment. Inhibiting glycolysis can reverse neutrophil dysfunction in ACLF patients.

Imbalance Between Soluble and Membrane-Bound CD100 Regulates Monocytes Activity in Hepatitis B Virus-Associated Acute-on-Chronic Liver Failure.

CD100 is an important immune semaphorin that is a secreted and membrane bound protein involved in infectious diseases. However, CD100 expression profile and the regulation to innate immune system in hepatitis B virus (HBV)-associated acute-on-chronic liver failure (ACLF) was not previously reported. The aim of this study was to investigate CD100 level and modulatory function of CD100 to CD14+ monocytes in HBV-ACLF patients. Plasma-soluble CD100 (sCD100) level and membrane-bound CD100 (mCD100) expression on peripheral CD14+ monocytes was analyzed in HBV-ACLF patients. CD14+ monocytes-induced cytotoxicity and CD14+ monocytes-mediated T cell activation in response to CD100 stimulation was also assessed in direct and indirect contact coculture culture systems. HBV-ACLF patients had lower plasma sCD100 and higher mCD100 level on CD14+ monocytes compared with asymptomatic HBV carriers, chronic hepatitis B patients, and controls. CD14+ monocytes from HBV-ACLF patients induced limited target Huh7.5 cell death and secreted less interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), and granzyme B in both direct and indirect contact coculture systems compared with controls. Recombinant sCD100 not only enhanced CD14+ monocytes-mediated Huh7.5 cell death and granzyme B secretion, but it also elevated CD14+ monocytes-induced IFN-γ/interleukin-17 production by CD4+ T cells as well as IFN-γ/TNF-α secretion by CD8+ T cells in HBV-ACLF patients. The current data indicated that severe inflammation induced sCD100/mCD100 imbalance to inactivate CD14+ monocytes response, which might be beneficial for the survival of HBV-ACLF patients.