Pathogenesis Of Acute Liver Failure Research Articles

Hyperactivation of succinate dehydrogenase promotes pyroptosis of macrophage via ROS-induced GSDMD oligomerization in acute liver failure

Acute liver failure (ALF) is a life-threatening disease with high mortality. Given excessive inflammation is one of the major pathogenesis of ALF, candidates targeting inflammation could be beneficial in the condition. Now the effect of hyperactivated succinate dehydrogenase (SDH) on promoting inflammation in lipopolysaccharide (LPS)-treated macrophages has been studied. However, its role and mechanism in ALF is not well understood. Here intraperitoneal injection of D-galactosamine and LPS was conducted in male C57BL/6 J mice to induce the ALF model. Dimethyl malonate (DMM), which inhibited SDH activity, was injected intraperitoneally 30 min before ALF induction. Macrophage pyroptosis was induced by LPS plus adenosine triphosphate (ATP). Pyroptosis-related molecules and proteins including GSDMD oligomer were examined by ELISA and western blot techniques, respectively. ROS production was assessed by fluorescence staining. The study demonstrated SDH activity was increased in liver macrophages from ALF mice. Importantly, DMM administration inhibited ROS, IL-1β, and pyroptosis-associated proteins levels (NLRP3, cleaved caspase-1, GSDMD-N, and GSDMD oligomers) both in the ALF model and in macrophages stimulated with LPS plus ATP. In vitro, ROS promoted pyroptosis by facilitating GSDMD oligomerization. Additionally, when ROS levels were increased through the addition of H2O2 to the DMM group, the levels of GSDMD oligomers were reverted. In conclusion, SDH hyperactivation promotes macrophage pyroptosis by ROS-mediated GSDMD oligomerization, suggesting that targeting this pathway holds promise as a strategy for treating ALF and other inflammatory diseases.

Dihydroquercetin improves experimental acute liver failure by targeting ferroptosis and mitochondria-mediated apoptosis through the SIRT1/p53 axis

BackgroundFerroptosis and mitochondria-mediated apoptosis are both involved in the pathogenesis of acute liver failure (ALF). Ferroptosis-produced reactive oxygen species (ROS) trigger the chain oxidation of polyunsaturated phospholipids and promote mitochondrial apoptosis. Dihydroquercetin (DHQ) also plays an important protective role against liver injury. PurposeHere, we aimed to investigate the protective effects of DHQ on ALF. We also explored the underlying mechanism. MethodsWe established a Lipopolysaccharide (LPS)/D-galactosamine (D-Gal)-induced ALF mouse model and tumor necrosis factor-α (TNF-α)/D-Gal-induced ALF LO2 cell model. 2′,7′-Dichlorofluorescein diacetate (DCFH-DA) and Dihydroethidium (DHE) were used to detect total ROS levels. Lipid ROS was assessed using C11-BODIPY flow cytometry. Lipid peroxidative products levels were detected using MDA ELISA assay and 4-hydroxynonenal (4-HNE) immunohistochemistry. QRT-PCR and western blots were used to test mRNA and protein expression levels, respectively. Cell viability was evaluated with CCK8 assay, and apoptosis was analyzed using flow cytometry. ResultsDHQ treatment improved LPS/D-Gal-induced ALF, as well as TNF-α/D-Gal-induced reductions in LO2 viability and increased sirtuin 1 (SIRT1) expression. DHQ pretreatment also reduced the accumulation of ROS, reduced lipid peroxidation, elevated mitochondrial membrane potentials (ΔΨm), and decreased liver cell apoptosis both in vivo and in vitro. Additionally, the knockdown of SIRT1 and p53 activator (Tenovin-6) treatment reversed DHQ's inhibitory effects on ferroptosis and mitochondria-mediated apoptosis in vitro. DHQ enhanced p53 deacetylation by both up-regulating SIRT1 expression and directly bonding to SIRT1. We also found that Tenovin-6′s stimulatory effects on ferroptosis and mitochondria-mediated apoptosis in the DHQ-treated LO2 ALF cell model were partially attenuated by overexpression of solute carrier family 7member 11 (SLC7A11), as well as by apoptotic protease activating factor 1 (Apaf-1) knockdown. ConclusionOur results suggest that DHQ alleviated ALF by inhibiting both ferroptosis and mitochondria-mediated apoptosis by regulating the SIRT1/p53 axis. Thus, DHQ may serve as a novel therapy for ALF.

Silencing of GDF11 suppresses hepatocyte apoptosis to relieve LPS/D-GalN acute liver failure.

In this paper, we generated a short hairpin RNA growth differentiation factor-11 (sh-GDF11) and evaluated the effects of sh-GDF11 on the pathogenesis of acute liver failure (ALF) in vitro and in vivo. Through bioinformatics study, the key gene related to ALF was assayed. Lipopolysaccharide (LPS) and D-galactoamine (D-GalN) were applied to establish the mouse model of LPS/D-GalN-induced liver injury, and TNF-α and D-Gal were used to construct an in vitro cell model, followed by treatment of sh-GDF11 for analysis of liver cell proliferation. Bioinformatics analysis showed that the protective effect of sh-GDF11 on ALF may be mediated by phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway. The results of in vitro study found that sh-GDF11 could promote cell proliferation and inhibit death by blocking the PI3K/Akt/mTOR signaling pathway. In vivo animal experiments further confirmed that sh-GDF11 could suppress hepatocyte apoptosis by inhibiting the PI3K/Akt/mTOR signaling pathway. sh-GDF11 relieved LPS/D-GalN-induced ALF by blocking the PI3K/Akt/mTOR signaling pathway, emphasizing its critical role in LPS/D-GalN-induced ALF treatment.

The role and mechanisms of macrophage polarization and hepatocyte pyroptosis in acute liver failure.

Acute liver failure (ALF) is a severe liver disease caused by disruptions in the body's immune microenvironment. In the early stages of ALF, Kupffer cells (KCs) become depleted and recruit monocytes derived from the bone marrow or abdomen to replace the depleted macrophages entering the liver. These monocytes differentiate into mature macrophages, which are activated in the immune microenvironment of the liver and polarized to perform various functions. Macrophage polarization can occur in two directions: pro-inflammatory M1 macrophages and anti-inflammatory M2 macrophages. Controlling the ratio and direction of M1 and M2 in ALF can help reduce liver injury. However, the liver damage caused by pyroptosis should not be underestimated, as it is a caspase-dependent form of cell death. Inhibiting pyroptosis has been shown to effectively reduce liver damage induced by ALF. Furthermore, macrophage polarization and pyroptosis share common binding sites, signaling pathways, and outcomes. In the review, we describe the role of macrophage polarization and pyroptosis in the pathogenesis of ALF. Additionally, we preliminarily explore the relationship between macrophage polarization and pyroptosis, as well as their effects on ALF.

Potential of circulating receptor-interacting protein kinase 3 levels as a marker of acute liver injury

The pathogenesis of acute liver failure (ALF) involves cell death. Necroptosis is a newly suggested programmed cell death, and receptor-interacting protein kinase 3 (RIPK3) has been reported as a marker for necroptosis. However, there are few reports on necroptosis in ALF. Therefore, we evaluated the role of cell death markers such as cytokeratin (CK) 18, cleaved CK (cCK) 18, and RIPK3 in ALF, as well as cytokines and hepatocyte growth factor (HGF). Seventy-one hospitalized patients with acute liver injury (38 nonsevere hepatitis [non-SH]/22 severe hepatitis [SH]/11 ALF) were studied. No significant difference was found for cytokines, but a substantial increase in HGF levels was found following the severity of hepatitis. The non-SH group had lower levels of CK18 and cCK18 than the SH/ALF group. RIPK3 was significantly lower in the non-SH/SH group than in the ALF group. HGF, RIPK3, and albumin levels were found to be important predictive variables. The present study suggests that cCK18, CK18, and RIPK3 are associated with the severity of hepatitis. RIPK3 and other markers related cell death may be useful for understanding the pathogenesis of ALF and as a prognostic marker of acute liver injury.

Reticuloendothelial activation and phenotypic alteration of peripheral monocytes with enhanced liver recruitment drive liver injury secondary to yellow phosphorus.

Monocytes and macrophages play a crucial role in the pathogenesis of acute liver failure (ALF). We aimed to study reticuloendothelial activation and its correlation with disease severity in commonly encountered yellow phosphorus (rodenticide)-induced hepatotoxicity patients. We also studied peripheral monocyte phenotype in a subset of patients. Reticuloendothelial activation markers were analyzed and correlated with disease severity score in a prospectively collected database of yellow phosphorus-related hepatoxicity patients between 2018 and 2021. In a prospective cohort of these patients and age-matched healthy controls, peripheral blood monocyte phenotyping was performed. Reticuloendothelial activation markers were analyzed in 67 patients [Age: 23(12-64) years; median (range), men: 25, acute liver injury (ALI): 38, ALF: 29, model for end-stage liver disease (MELD) score: 28 (7-40)] of yellow phosphorus-induced hepatotoxicity. Serum ferritin (927; 10.3-34807ng/mL), sCD163 (4.59; 0.11-12.7μg/mL), sCD25 (3050; 5.6-17300pg/mL) and plasma von Willebrand factor (423.5, 103-1106IU/dL) were increased and showed significant correlation with liver disease severity assessed by MELD score (ρ=0.29, ρ=0.6, ρ=0.56 and ρ=0.46 respectively). Phenotyping and serum immune markers were performed in seven patients (M: 4; age: 27, 15-37years; median, range; MELD score: 36, 21-40) and compared with eight healthy controls. Increase in classical monocytes and decrease in patrolling and intermediate monocyte subsets were observed in ALF cohort. HLA-DRlow CD163hi (immune exhaustion), CD64hi (immune complex-mediated response), and CCR2hi (liver homing) monocyte phenotype was noted. Altered peripheral monocyte phenotype with enhanced liver homing and macrophage activation, suggests important role of innate immune activation, and provides a potential therapeutic target, in yellow phosphorus-induced hepatotoxicity.

The role of the canonical nf-κb signaling pathway in the development of acute liver failure

ABSTRACT As a clinical emergency with a high mortality rate, the treatment of acute liver failure has been paid attention to by society. At present, liver transplantation is the most effective treatment for acute liver failure, but there is still an insufficient supply of liver sources and a poor prognosis. In view of the current therapeutic development of this disease, more researchers have turned their attention to the research of drugs related to the NF-κB pathway. The NF-κB canonical pathway has been proven to play a role in a variety of diseases, regulating inflammation, apoptosis, and other physiological processes. More and more evidence shows that the NF-κB canonical pathway regulates the pathogenesis of acute liver failure. In this review, we will summarize the regulation process of the NF-κB canonical pathway on acute liver failure, and develop a new way to treat acute liver failure by targeting the components of the pathway.

Elevated Pancreatic Enzymes Associated with Acute Liver Injury Were Mediated by Tumor Necrosis Factor-Alpha Signaling

Background: Acute liver failure (ALF) is caused by massive hepatocyte death and accompanied by severe coagulation disorder and encephalopathy. It often leads to multiple organ failure and subsequently death. However, the association between ALF and other organ failure remains unclear. Objectives: Here, we evaluated patients with acute liver injury (ALI) and elevated pancreatic enzymes to demonstrate the association between ALI and pancreatic disorder. Methods: We conducted a single-center retrospective study to analyze patients with ALI. Between 2012 and 2017, 163 patients with ALI were treated in our hospital. We stratified patients based on whether serum amylase and lipase were elevated above 1.5 times the upper limit of normal. We compared the baseline characteristics, severity, prognosis, and serum cytokine levels between the two groups. Results: Of the 163 patients, 75 (54.0%) presented elevated pancreatic enzymes above 1.5 times the upper limit of normal. Computed tomography imaging findings associated with pancreatitis were observed in 29 patients (17.8%). The elevation of pancreatic enzymes was associated with ALI severity. High level of serum tumor necrosis factor-alpha (TNF-α) was associated with the elevation of pancreatic enzymes (elevation group Vs. no elevation group: 134.0 ± 177.2 pg/mL Vs. 89.4 ± 159.8 pg/mL). Conclusions: The elevation of pancreatic enzymes was often accompanied by ALI and associated with ALI severity. TNF-α signaling was involved in the elevation of pancreatic enzymes. It is possible that the pancreatic disorder reflected ALI severity, consequently correlated with mortality, and did not directly aggravate ALI pathogenesis. These findings provide novel insights into the pathogenesis of ALF.

Возможности и перспективы применения клеточных технологий при острой печеночной недостаточности в эксперименте

The article provides information on the relevance of the problem of treating acute liver failure.The main etiological factors and the general concept of pathogenesis are reflected according to the modernachievements of hepatology. An imbalance in the immune system is considered as one of the main links inthe pathogenesis of acute liver failure. At the same time, cell therapy is presented as a promising directionin the treatment of severe acute liver damage. The article specifies the possibilities of using hepatocytetransplantation in liver failure.

TTP protects against acute liver failure by regulating CCL2 and CCL5 through m6A RNA methylation.

Tristetraprolin (TTP), an important immunosuppressive protein regulating mRNA decay through recognition of the AU-rich elements (AREs) within the 3′-UTRs of mRNAs, participates in the pathogenesis of liver diseases. However, whether TTP regulates mRNA stability through other mechanisms remains poorly understood. Here, we report that TTP was upregulated in acute liver failure (ALF), resulting in decreased mRNA stabilities of CCL2 and CCL5 through promotion of N6-methyladenosine (m6A) mRNA methylation. Overexpression of TTP could markedly ameliorate hepatic injury in vivo. TTP regulated the mRNA stabilization of CCL2 and CCL5. Interestingly, increased m6A methylation in CCL2 and CCL5 mRNAs promoted TTP-mediated RNA destabilization. Moreover, induction of TTP upregulated expression levels of WT1 associated protein, methyltransferase like 14, and YT521-B homology N6-methyladenosine RNA binding protein 2, which encode enzymes regulating m6A methylation, resulting in a global increase of m6A methylation and amelioration of liver injury due to enhanced degradation of CCL2 and CCL5. These findings suggest a potentially novel mechanism by which TTP modulates mRNA stabilities of CCL2 and CCL5 through m6A RNA methylation, which is involved in the pathogenesis of ALF.

Protective Role of 4-Octyl Itaconate in Murine LPS/D-GalN-Induced Acute Liver Failure via Inhibiting Inflammation, Oxidative Stress, and Apoptosis.

Oxidative stress, inflammation, and apoptosis are crucial in the pathogenesis of acute liver failure (ALF). 4-Octyl itaconate (OI) showed antioxidative and anti-inflammatory properties in many disease models. However, its role in lipopolysaccharide- (LPS-)/D-galactosamine- (D-GalN-) induced ALF is still not investigated. Here, we established an ALF murine model induced by LPS/D-GalN administration. And we found that OI improved survival rate in the murine ALF model. Our results also showed that OI alleviated LPS/D-GalN-induced hepatic histopathological injury and reduced the serum activities of alanine transaminase and aspartate transaminase. Moreover, OI reduced serum levels of proinflammatory cytokines such as monocyte chemotactic protein-1, tumor necrosis factors-α, and interlukin-6. Additionally, OI mitigated oxidative stress and alleviated lipid peroxidation in a murine model of ALF. This was evaluated by a reduction of thiobarbituric acid reactive substances (TBARS) in liver tissues. In addition, OI increased the ratio of reduced glutathione/oxidized glutathione and the activities of antioxidant enzymes including catalase and superoxide dismutase. Moreover, the apoptosis of hepatocytes in the liver was inhibited by OI. Furthermore, we found that OI inhibited LPS-induced nuclear translocation and activation of factor-kappa B (NF-κB) p65 in macrophages which could be inhibited by OI-induced activation of nuclear factor erythroid-2-related factor (Nrf2) signaling. Additionally, D-GalN-induced reactive oxygen species (ROS) generation and apoptosis in hepatocytes were inhibited by OI-induced activation of Nrf2 signaling. Therefore, the underlying mechanism for OI's protective effect in LPS/D-GalN-induced ALF may be associated with deactivation of NF-κB signaling in macrophages to reduce inflammation and inhibition of ROS-related hepatocyte apoptosis by activating Nrf2. In conclusion, OI showed a protective role in LPS/D-GalN-induced ALF by reducing inflammation, enhancing antioxidant capacity, and inhibiting cell apoptosis.

Complement-5 Inhibition Deters Progression of Fulminant Hepatitis to Acute Liver Failure in Murine Models

Background & AimsAcute liver failure (ALF) is a life-threatening condition with limited treatment alternatives. ALF pathogenesis seemingly involves the complement system. However, no complement-targeted intervention has been clinically applied. In this study, we aimed to investigate the potential of Complement-5 (C5)-targeted ALF treatment.MethodsALF was induced in C5-knockout (KO, B10D2/oSn) mice and their wild-type (WT) counterparts (B10D2/nSn) through intraperitoneal lipopolysaccharide (LPS) and d-galactosamine (D-GalN) administration. Thereafter, monoclonal anti-C5 antibody (Ab) or control immunoglobulin was administered intravenously. Furthermore, a selective C5a-receptor (C5aR) antagonist was administered to WT mice to compare its efficacy with that of anti-C5-Ab-mediated total C5 inhibition. We clarified the therapeutic effect of delayed anti-C5-Ab administration after LPS/D-GalN challenge. We also assessed the efficacy of anti-C5-Ab in another ALF model, using concanavalin-A.ResultsLiver injury was evident 6 hours after LPS/D-GalN administration. C5-KO and anti-C5-Ab treatment significantly improved overall animal survival and significantly reduced serum transaminase and high-mobility group box-1 release with decreased histological tissue damage. This improvement was characterized by significantly reduced CD41+ platelet aggregation, maintained F4/80+ cells, and less infiltration of CD11+/Ly6-G+ cells with lower cytokine/chemokine expression. Furthermore, C5-KO and anti-C5-Ab downregulated tumor necrosis factor-α production by macrophages before inducing marked liver injury. Moreover, single-stranded-DNA cells and caspase activation were reduced, indicating significant attenuation of apoptosis. Anti-C5-Ab treatment protected the liver more effectively than the C5aR antagonist, and its delayed doses were hepatoprotective. In addition, anti-C5-Ab treatment was effective against concanavalin-A–induced ALF.ConclusionsC5 inhibition effectively suppresses progression to ALF in mice models of fulminant hepatitis, serving as a new potential treatment strategy for ALF.

Application of mesenchymal stem cell exosomes and their drug-loading systems in acute liver failure.

Stem cell exosomes are nanoscale membrane vesicles released from stem cells of various origins that can regulate signal transduction pathways between liver cells, and their functions in intercellular communication have been recognized. Due to their natural substance transport properties and excellent biocompatibility, exosomes can also be used as drug carriers to release a variety of substances, which has great prospects in the treatment of critical and incurable diseases. Different types of stem cell exosomes have been used to study liver diseases. Due to current difficulties in the treatment of acute liver failure (ALF), this review will outline the potential of stem cell exosomes for ALF treatment. Specifically, we reviewed the pathogenesis of acute liver failure and the latest progress in the use of stem cell exosomes in the treatment of ALF, including the role of exosomes in inhibiting the ALF inflammatory response and regulating signal transduction pathways, the advantages of stem cell exosomes and their use as a drug‐loading system, and their pre‐clinical application in the treatment of ALF. Finally, the clinical research status of stem cell therapy for ALF and the current challenges of exosome clinical transformation are summarized.

Next-generation sequencing of the intrahepatic antibody repertoire delineates a unique B-cell response in HBV-associated acute liver failure.

Hepatitis B virus (HBV) is a major cause of acute liver failure (ALF) worldwide. While liver damage in classic acute hepatitis B is believed to be T-cell mediated, the pathogenesis of HBV-associated ALF remains largely unknown. Access to liver specimens from well-characterized patients with HBV-associated ALF provided us with the opportunity to perform next-generation sequencing (NGS) of the entire VH repertoires of IgM and IgG from the livers of four ALF patients, a control liver donor and a patient with chronic HBV infection. We found that ALF is not associated with expansion of specific B-cell lineages. However, NGS showed that the intrahepatic VH repertoires from ALF patients were characterized by the abundant presence of antibodies in germline configuration in contrast to their marginal prevalence in controls. Moreover, NGS identified a large number of VH genes in germline configuration with identical VDJ sequences in the IgM and IgG repertoires in all four ALF patients, indicating that isotype switch from IgM to IgG had occurred without somatic hypermutation. The results of this study indicate that the presence of intrahepatic antibodies in unmutated germline configuration is a broad phenomenon in the global antibody repertoire generated from total RNA derived from whole-liver tissue that is strongly associated with ALF, suggesting a major role of T cell-independent humoral immunity in the pathogenesis of ALF.

Roles of hepatic stellate cells in acute liver failure: From the perspective of inflammation and fibrosis.

Acute liver failure (ALF) usually results in hepatocellular dysfunction and coagulopathy and carries a high mortality rate. Hepatic stellate cells (HSCs) are famous for their role in liver fibrosis. Although some recent studies revealed that HSCs might participate in the pathogenesis of ALF, the accurate mechanism is still not fully understood. This review focuses on the recent advances in understanding the functions of HSCs in ALF and revealed both protective and promotive roles during the pathogenesis of ALF: HSC activation participates in the maintenance of cell attachment and the architecture of liver tissue via extracellular matrix production and assists liver regeneration by producing growth factors; and HSC inflammation plays a role in relaying inflammation signaling from sinusoids to parenchyma via secretion of inflammatory cytokines. A better understanding of roles of HSCs in the pathogenesis of ALF may lead to improvements and novel strategies for treating ALF patients.

Role of humoral immunity against hepatitis B virus core antigen in the pathogenesis of acute liver failure

Hepatitis B virus (HBV)-associated acute liver failure (ALF) is a dramatic clinical syndrome leading to death or liver transplantation in 80% of cases. Due to the extremely rapid clinical course, the difficulties in obtaining liver specimens, and the lack of an animal model, the pathogenesis of ALF remains largely unknown. Here, we performed a comprehensive genetic and functional characterization of the virus and the host in liver tissue from HBV-associated ALF and compared the results with those of classic acute hepatitis B in chimpanzees. In contrast with acute hepatitis B, HBV strains detected in ALF livers displayed highly mutated HBV core antigen (HBcAg), associated with increased HBcAg expression ex vivo, which was independent of viral replication levels. Combined gene and miRNA expression profiling revealed a dominant B cell disease signature, with extensive intrahepatic production of IgM and IgG in germline configuration exclusively targeting HBcAg with subnanomolar affinities, and complement deposition. Thus, HBV ALF appears to be an anomalous T cell-independent, HBV core-driven B cell disease, which results from the rare and unfortunate encounter between a host with an unusual B cell response and an infecting virus with a highly mutated core antigen.

Anti‑apoptotic effects of human placental hydrolysate against hepatocyte toxicity invivo and invitro.

Apoptosis and oxidative stress are essential for the pathogenesis of acute liver failure and fulminant hepatic failure. Human placental hydrolysate (hPH) has been reported to possess antioxidant and anti-inflammatory properties. In the present study, the protective effects of hPH against D-galactosamine (D-GalN)- and lipopolysaccharide (LPS)-induced hepatocyte apoptosis were investigated in vivo. In addition, the molecular mechanisms underlying the anti-apoptotic activities of hPH against D-GalN-induced cell death in vitro were examined. Male Sprague-Dawley rats were injected with D-GaIN/LPS with or without the administration of hPH. Rats were sacrificed 24 h after D-GaIN/LPS intraperitoneal injection, and the blood and liver samples were collected for future inflammation and hepatotoxicity analyses. Changes in cell viability, apoptosis protein expression, mitochondrial mass, mitochondrial membrane potential, reactive oxygen species generation, and the levels of proteins and mRNA associated with a protective mechanism were determined in HepG2 cells pretreated with hPH for 2 h prior to D-GalN exposure. The findings suggested that hPH treatment effectively protected against D-GalN/LPS-induced hepatocyte apoptosis by reducing the levels of alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, interleukin-6, and tumor necrosis factor-α, and increasing the level of proliferating cell nuclear antigen. It was also found that hPH inhibited the apoptotic cell death induced by D-GalN. hPH activated the expression of antioxidant enzymes, including superoxide dismutase, glutathione peroxidase, and catalase, which were further upregulated by the Kelch-like ECH2-associated protein 1-p62-nuclear factor-erythroid 2-related factor 2 pathway, a component of oxidative stress defense mechanisms. Furthermore, hPH markedly reduced cytosolic and mitochondrial reactive oxygen species and rescued mitochondrial loss and dysfunction through the reduction of damage-regulated autophagy modulator, p53, and C/EBP homologous protein. Collectively, hPH exhibited a protective role in hepatocyte apoptosis by inhibiting oxidative stress and maintaining cell homeostasis. The underlying mechanisms may be associated with the inhibition of endoplasmic reticulum stress and minimization of the autophagy progress.

Bioinformatic identification of key genes and pathways that may be involved in the pathogenesis of HBV-associated acute liver failure

In order to explore the molecular mechanisms behind the pathogenesis of acute liver failure (ALF) associated with hepatitis B virus (HBV) infection, the present study aimed to identify potential key genes and pathways involved using samples from patients with HBV-associated ALF. The GSE38941 array dataset was downloaded from the Gene Expression Omnibus database, and differentially expressed genes (DEGs) between 10 liver samples from 10 healthy donors and 17 liver specimens from 4 patients with HBV-associated ALF were analyzed using the Linear Models for Microarray Data package. Gene Ontology and KEGG pathway enrichment analyses of the DEGs were performed, followed by functional annotation of the genes and construction of a protein–protein interaction (PPI) network. Subnetwork modules were subsequently identified and analyzed. In total, 3142 DEGs were identified, of which 1755 were upregulated and 1387 were downregulated. The extracellular exosome, immune response, and inflammatory response pathways may potentially be used as biomarkers of ALF pathogenesis. In total, 17 genes (including CCR5, CXCR4, ALB, C3, VGEFA, and IGF1) were identified as hub genes in the PPI network and may therefore be potential marker genes for HBV-associated ALF.

Von Willebrand factor protects against acute CCl4-induced hepatotoxicity through phospho-p38 MAPK signaling pathway inhibition.

The blood glycoprotein von Willebrand factor (vWF) is involved in coagulopathy and inflammation; however, its role in the pathogenesis of acute liver failure, as suggested by its higher expression levels in such patients, remains unknown. In this study, vWF-knockout (KO) mice showed more severe carbon tetrachloride (CCl4)-induced liver injury than wild-type mice. Patients with acute liver injury also showed elevated vWF protein activity and expression in liver tissues, as compared to healthy individuals. Using the mouse model and cultured human umbilical vein endothelial cells (HUVECs), CCl4 was found to directly increase vWF protein expression through interaction with the highly expressed vWF receptor, GPIbα. Microarray analysis revealed that the genes showing the most differential expression in response to CCl4-induced liver injury and vWF deficiency were related to the MAPK signaling pathway. Subsequent inhibition of vWF protein activity in HUVECs led to activation of the MAPK signal pathway and elevated production of FGL2, and treatment with a phospho-p38 inhibitor suppressed the CCl4-induced production of FGL2. Exposure of liver sinusoidal endothelial cells isolated from the vWF-KO acute liver injury model mice to phospho-p38 inhibitor also decreased FGL2 expression. The vWF/GPIbα axis plays a protective role against development of acute liver injury by attenuating FGL2 production through the MAPK signaling pathway. Collectively, these data provide insight into the pathogenesis of acute liver injury and a potential novel strategy for its treatment.

P53 Regulates Progression of Injury and Liver Regeneration After Acetaminophen Overdose

Liver regeneration in response to acetaminophen (APAP) overdose is a critical determinant of final patient outcome. Intricate cellular signaling during liver regeneration triggers liver cell proliferation, wound healing (if required) and restoration of liver mass and function. The p53 tumor suppressor protein is a critical regulator of cell cycle and apoptosis. However its role in liver regeneration after APAP overdose induced Acute Liver Failure (ALF) is not known. The pathogenesis of acute liver failure induced by APAP overdose can be divided into three phases including initiation of injury (formation of a reactive metabolite NAPQI and protein adducts) progression of injury (oxidative stress, mitochondrial and DNA damage resulting in necrosis) and regeneration/recovery phase (cell proliferation, angiogenesis and tissue repair). Here we show that p53 plays a critical role in inhibiting progression of injury and liver regeneration following APAP overdose mediated Acute Liver Injury (ALI). Eight‐week‐old male WT and p53KO mice (C57BL/6J background) were studied over time course of 0 to 96 hr following treatment with APAP300 (300mg/kg). Histology and serum ALT analysis showed similar liver injury in WT and p53KO mice at 1 and 12 hr however p53KO mice had significantly higher injury at 24 hr after APAP treatment. Interestingly, despite higher liver injury p53KO mice recovered equally to WT mice at 48 and 96 hr after APAP administration. Transcriptome analysis using liver RNA at 12, 24, 48hr from both groups revealed that p53KO mice had disrupted metabolic homeostasis, induced pro‐inflammatory and proliferative signaling. Further, molecular analysis of these pathways was done to confirm the findings. p53KO mice showed prolonged steatosis, lower mitochondrial DNA content, reduced expression of TFAM and mitochondrial complexes up to 24hr correlating with prolonged higher liver injury. p53 targets involved in fatty acid homeostasis, SREBP2 protein and GAMT mRNA expression correlated with prolonged steatosis in p53KO group. Liver regeneration determined by PCNA staining and cell cycle protein expression demonstrated that p53KO mice had rapid liver regeneration. Western blot analysis of EGFR, ERK and AKT showed sustained growth factor signaling in p53KO mice than WT mice after APAP treatment. These data illustrate that p53 has stage specific role during APAP‐induced ALF. p53 prevents progression of liver injury by maintaining mitochondrial and metabolic homeostasis after APAP overdose induced ALI. Further, p53 regulates initiation of liver regeneration through inflammatory and proliferative signaling after APAP overdose. These studies have revealed a novel role of p53 in acute liver injury pathogenesis.Support or Funding InformationNational Center for Research Resources (5P20RR021940‐07) Liver Scholar Award by AASLD/American Liver Foundation R01 DK098414