Role of the perforin/granzyme cell death pathway in D-Gal/LPS-induced inflammatory liver injury

The progress to establish optimal animal models for the study of acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) defines a complicated and multifaceted syndrome characterized by acute liver dysfunction following an acute insult on the basis of chronic liver diseases. It is usually concurrent with bacterial infection and multi-organ failure resulting in high short-term mortality. Based on the cohort studies in ACLF worldwide, the clinical course of ACLF was demonstrated to comprise three major stages including chronic liver injury, acute hepatic/extrahepatic insult, and systemic inflammatory response caused by over-reactive immune system especially bacterial infection. However, due to the lack of optimal experimental animal models for ACLF, the progress of basic study on ACLF is limping. Though several experimental ACLF models were established, none of them can recapitulate and simulate the whole pathological process of ACLF patients. Recently, we have developed a novel mouse model for ACLF combining chronic liver injury [injection of carbon tetrachloride (CCl₄) for 8 weeks], acute hepatic insult (injection of a double dose CCl₄), and bacterial infection (intraperitoneal injection of Klebsiella pneumoniae), which could recapitulate the major clinical features of patients with ACLF worsened by bacterial infection.

Blood Coral Polysaccharide Helps Prevent D-Gal/LPS-Induced Acute Liver Failure in Mice

Objective

The liver protection of blood coral polysaccharide (BCP) was investigated.

Materials and Methods

We evaluated the effect of BCP on liver pathology, liver function, oxidation and inflammation-related indicators of D-Gal/LPS-induced acute liver failure (ALF) mice in vivo.

Results

Liver index and liver pathology observation in mice showed that BCP could inhibit liver tissue swelling and hemorrhage, hepatocyte damage, and inflammatory infiltration in ALF. Serum liver function results showed that BCP effectively inhibits the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), total bilirubin (TBil), alkaline phosphatase (AKP), myeloperoxidase (MPO). High dose-blood coral polysaccharide (H-BCP) was better than silymarin. Serum antioxidant and immune results showed that BCP increased the levels of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH), and glutathione peroxidase (GSH-Px), and inhibited the levels of malondialdehyde (MDA) and nitric oxide (NO). Also, BCP increased immunoglobulins G (IgG) and A (IgA) levels, thereby enhancing humoral immunity. Liver anti-inflammatory ELISA results showed that BCP reduced the levels of interleukin (IL)-6, IL-1β, IL-17, tumor necrosis factor (TNF)-α, and interferon (IFN)-γ, and enhanced the level of anti-inflammatory factor IL-10. H-BCP was the most effective treatment. Real-time quantitative reverse transcription-polymerase chain reaction (RT-qPCR) of liver tissues confirmed that BCP increases the relative expression levels of antioxidant and anti-inflammatory-related cuprozinc superoxide dismutase (Cu/Zn-SOD, SOD1), manganese superoxide dismutase (Mn-SOD, SOD2), CAT, GSH, GSH-Px, and IL-10. In contrast, it inhibits inflammation-related genes IL-6, IL-1β, IL-17, TNF-α, IFN-γ, inducible nitric oxide synthase (iNOS, NOS2), and cyclooxygenase (COX)-2. In addition, BCP also inhibits the nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) and enhance B-cell inhibitor-α (IκB-α) gene relative expression in the liver, which may be related to NF-κB pathway inhibition.

Conclusion

BCP prevents D-Gal/LPS-induced ALF in mice, and its effect is concentration dependent.

Acute-on-chronic liver failure (ACLF) in 2022: have novel treatment paradigms already arrived?

INTRODUCTION

Acute-on-chronic failure (ACLF) is a recognized syndrome in patients with chronic liver disease and is characterized by acute decompensation, organ failure(s), and a high short-term mortality. ACLF is often triggered by ongoing alcohol consumption, gastrointestinal bleeding and/or infections, and is pathophysiologically characterized by uncontrolled systemic inflammation coupled with paradoxical immunoparesis. Patients with ACLF require prompt and early recognition. Management requires extensive utilization of clinical resources often including escalation to intensive care.

AREAS COVERED

Currently, there are no specific targeted treatments for established ACLF, and management revolves around treating underlying precipitants and providing organ support. In this article, we review the epidemiology and pathophysiology of ACLF and summarize recent advances in management strategies of this syndrome, focusing specifically on novel emerging therapies.

EXPERT COMMENTARY

ACLF is a challenging condition with rapid clinical course, high short-term mortality and varying clinical phenotypes. Management of ACLF is broadly focused on supportive care often in an intensive care setting with liver transplantation proving to be an increasingly relevant and effective rescue therapy. This disease has clear pathogenesis and epidemiological burden, thus distinguishing it from decompensated cirrhosis; there is clear clinical need for the development of specific and nuanced therapies to treat this condition.

Antioxidant and Inflammatory Effects of Nelumbo nucifera Gaertn. Leaves

This study is aimed at identifying the bioactive components in lotus leaf flavonoid extract (LLFE) and analyzing the antioxidant and anti-inflammatory activities of LLFE in vitro and in vivo. The flavonoids in LLFE were determined by UHPLC-MS/MS. The effect of LLFE on damaged 293T cells (H2O2, 0.3 mmol/L) was determined by MTT assay, and the activity of antioxidant enzymes was measured by kits. We studied the antioxidant and anti-inflammatory effects of LLFE on D-Gal/LPS (30 mg/kg·bw and 3 μg/kg·bw)-induced aging mice. We also evaluated the main organ index, pathological changes in the liver, lung, and kidney, liver function index, biochemical index, cytokine level, and mRNA expression level in serum and liver. The results showed that LLFE contains baicalein, kaempferol, kaempferid, quercetin, isorhamnetin, hyperoside, lespenephryl, and rutin. LLFE reduced the oxidative damage sustained by 293T cells, increased the levels of SOD, CAT, GSH, and GSH-Px, and decreased the level of MDA. The animal studies revealed that LLFE reduced oxidative damage and inflammation in injured mice, inhibited increases in AST, ALT, MDA, and NO, increased SOD, CAT, GSH, and GSH-Px levels, upregulated anti-inflammatory cytokines IL-10 and IL-12, and downregulated proinflammatory cytokines IL-6, IL-1β, TNF-α, and IFN-γ. Furthermore, the expression of antioxidant- and anti-inflammatory-related mRNA was consistent with the above results.

Establishment of a murine model of acute-on-chronic liver failure with multi-organ dysfunction

BACKGROUND AND AIMS

Acute-on-chronic liver failure (ACLF) is a distinct clinical entity with high probability of organ failure and mortality. Since patients generally present late, experimental models are needed to understand the pathophysiology and natural course of the disease.

METHODOLOGY

To reproduce the syndrome of ACLF, chronic liver disease was induced in C57BL6 mice (6-8 weeks; approximately 20-24 g weight) by intraperitoneal administration of carbon tetrachloride (CCl₄) for 10 weeks followed by an acute injury with acetaminophen (APAP) and lipopolysaccharide (LPS). Blood, ascitic fluid, and organs were collected to study cell death, regeneration, and fibrosis.

RESULTS

At 24 h post-APAP/LPS infusion, the liver tissue showed increased hepatocyte ballooning and endothelial cell TUNEL positivity. This was followed by progressive hepatocyte necrosis from perivascular region at day 7 to lobular region by day 11. ACLF (day 7 and day 11) animals showed increase in bilirubin (p < 0.05), prothrombin time (p < 0.0001), blood ammonia (p < 0.001), and portal pressure post-acute hepatocellular injury similar to human ACLF. Ascites was noticed by day 11 with median serum-ascites albumin gradient of 1.2 (1.1-1.3) g/dL. In comparison to cirrhosis, ACLF group (day 7 and day 11) showed significant decrease in Sirius red (p ≤ 0.0001), collagen1 (p < 0.0001), and a-SMA proportionate area (p < 0.0001) with loss of hepatocytes regeneration (p < 0.005). At day 11, ACLF animals also showed significant increase in serum creatinine (p < 0.05) and acute tubular necrosis suggestive of organ failure, compared to cirrhotic animals.

CONCLUSION

The CCL4/APAP/LPS (CALPS) model of ACLF mimics the clinical, biochemical, and histological features of ACLF with demonstrable progressive hepatocellular necrosis, liver failure, impaired regeneration, development of portal hypertension, and organ dysfunction in an animal with chronic liver disease.

BRG1 Links TLR4 Trans-Activation to LPS-Induced SREBP1a Expression and Liver Injury

Multiple organ failure is one of the most severe consequences in patients with septic shock. Liver injury is frequently observed during this pathophysiological process. In the present study we investigated the contribution of Brahma related gene 1 (BRG1), a chromatin remodeling protein, to septic shock induced liver injury. When wild type (WT) and liver conditional BRG1 knockout (LKO) mice were injected with lipopolysaccharide (LPS), liver injury was appreciably attenuated in the LKO mice compared to the WT mice as evidenced by plasma ALT/AST levels, hepatic inflammation and apoptosis. Of interest, there was a down-regulation of sterol response element binding protein 1a (SREBP1a), known to promote liver injury, in the LKO livers compared to the WT livers. BRG1 did not directly bind to the SREBP1a promoter. Instead, BRG1 was recruited to the toll-like receptor 4 (TLR4) promoter and activated TLR4 transcription. Ectopic TLR4 restored SREBP1a expression in BRG1-null hepatocytes. Congruently, adenovirus carrying TLR4 or SREBP1a expression vector normalized liver injury in BRG1 LKO mice injected with LPS. Finally, a positive correlation between BRG1 and TLR4 expression was detected in human liver biopsy specimens. In conclusion, our data demonstrate that a BRG1-TLR4-SREBP1a axis that mediates LPS-induced liver injury in mice.

Targeting of Perforin Inhibitor into the Brain Parenchyma Via a Prodrug Approach Can Decrease Oxidative Stress and Neuroinflammation and Improve Cell Survival

The cytolytic protein perforin has a crucial role in infections and tumor surveillance. Recently, it has also been associated with many brain diseases, such as neurodegenerative diseases and stroke. Therefore, inhibitors of perforin have attracted interest as novel drug candidates. We have previously reported that converting a perforin inhibitor into an L-type amino acid transporter 1 (LAT1)-utilizing prodrug can improve the compound's brain drug delivery not only across the blood-brain barrier (BBB) but also into the brain parenchymal cells: neurons, astrocytes, and microglia. The present study evaluated whether the increased uptake into mouse primary cortical astrocytes and subsequently improvements in the cellular bioavailability of this brain-targeted perforin inhibitor prodrug could enhance its pharmacological effects, such as inhibition of production of caspase-3/-7, lipid peroxidation products and prostaglandin E2 (PGE2) in the lipopolysaccharide (LPS)-induced neuroinflammation mouse model. It was demonstrated that increased brain and cellular drug delivery could improve the ability of perforin inhibitors to elicit their pharmacological effects in the brain at nano- to picomolar levels. Furthermore, the prodrug displayed multifunctional properties since it also inhibited the activity of several key enzymes related to Alzheimer's disease (AD), such as the β-site amyloid precursor protein (APP) cleaving enzyme 1 (BACE1), acetylcholinesterase (AChE), and most probably also cyclooxygenases (COX) at micromolar concentrations. Therefore, this prodrug is a potential drug candidate for preventing Aβ-accumulation and ACh-depletion in addition to combatting neuroinflammation, oxidative stress, and neural apoptosis within the brain. Graphical abstract.

Interleukin-22 ameliorates acute-on-chronic liver failure by reprogramming impaired regeneration pathways in mice

BACKGROUND & AIMS

Acute-on-chronic liver failure (ACLF) is a clinical syndrome defined by liver failure on pre-existing chronic liver disease. It is often associated with bacterial infection and high short-term mortality. Experimental models that fully reproduce ACLF are lacking, so too are effective pharmacological therapies for this condition.

METHODS

To mimic ACLF conditions, we developed a severe liver injury model by combining chronic injury (chronic carbon tetrachloride [CCl4] injection), acute hepatic insult (injection of a double dose of CCl4), and bacterial infection (intraperitoneal injection of bacteria). Serum and liver samples from patients with ACLF or acute drug-induced liver injury (DILI) were used. Liver injury and regeneration were assessed to ascertain the potential benefits of interleukin-22 (IL-22Fc) administration.

RESULTS

This severe liver injury model recapitulated some of the key features of clinical ACLF, including acute-on-chronic liver injury, bacterial infection, multi-organ injury, and high mortality. Liver regeneration in this model was severely impaired because of a shift from the activation of the pro-regenerative IL-6/STAT3 pathway to the anti-regenerative IFN-γ/STAT1 pathway. The impaired IL-6/STAT3 activation was due to the inability of Kupffer cells to produce IL-6; whereas the enhanced STAT1 activation was due to a strong innate immune response and subsequent production of IFN-γ. Compared to patients with DILI, patients with ACLF had higher levels of IFN-γ but lower liver regeneration. IL-22Fc treatment improved survival in ACLF mice by reversing the STAT1/STAT3 pathway imbalance and enhancing expression of many antibacterial genes in a manner involving the anti-apoptotic protein BCL2.

CONCLUSIONS

Acute-on-chronic liver injury or bacterial infection is associated with impaired liver regeneration due to a shift from a pro-regenerative to an anti-regenerative pathway. IL-22Fc therapy reverses this shift and attenuates bacterial infection, thus IL-22Fc may have therapeutic potential for ACLF treatment.

LAY SUMMARY

A mouse model combining chronic liver injury, acute hepatic insult, and bacterial infection recapitulates some of the key features of acute-on-chronic liver failure (ACLF) in patients. Both fibrosis and bacterial infection contribute to the impaired regenerative capacity of the liver in patients with ACLF. Herein, we show that IL-22Fc therapy improves ACLF by reprogramming impaired regenerative pathways and attenuating bacterial infection. Thus, it may have therapeutic potential for patients with ACLF.

AKT activator SC79 protects hepatocytes from TNF-α-mediated apoptosis and alleviates d-Gal/LPS-induced liver injury

Tumor necrosis factor-α (TNF-α) is a highly pleiotropic cytokine executing biological functions as diverse as cell proliferation, metabolic activation, inflammatory responses, and cell death. TNF-α can induce multiple mechanisms to initiate apoptosis in hepatocytes leading to the subsequent liver injury. Since the phosphoinositide-3-kinase/protein kinase B (PI3K/Akt) pathway is known to have a protective role in death factor-mediated apoptosis, it is our hypothesis that activation of Akt may represent a therapeutic strategy to alleviate TNF-α-induced hepatocyte apoptosis and liver injury. We report here that the Akt activator SC79 protects hepatocytes from TNF-α-induced apoptosis and protects mice from d-galactosamine (d-Gal)/lipopolysaccharide (LPS)-induced TNF-α-mediated liver injury and damage. SC79 not only enhances the nuclear factor-κB (NF-κB) prosurvival signaling in response to TNF-α stimulation, but also increases the expression of cellular FLICE (FADD-like IL-1β-converting enzyme)-inhibitory protein L and S (FLIP_L/S), which consequently inhibits the activation of procaspase-8. Furthermore, pretreatment of the PI3K/Akt inhibitor LY294002 reverses all the SC79-induced hepatoprotective effects. These results strongly indicate that SC79 protects against TNF-α-induced hepatocyte apoptosis and suggests that SC79 is likely a promising therapeutic agent for ameliorating the development of liver injury. NEW & NOTEWORTHY SC79 protects hepatocytes from TNF-α-mediated apoptosis and mice from Gal/LPS-induced liver injury and damage. Cytoprotective effects of SC79 against TNF-α act through both AKT-mediated activation of NF-κB and upregulation of FLIP_L/S.

Promising immunotherapy: Highlighting cytokine-induced killer cells

For many years, cancer therapy has appeared to be a challenging issue for researchers and physicians. By the introduction of novel methods in immunotherapy, the prospect of cancer therapy even more explained than before. Cytokine-induced killer (CIK) cell-based immunotherapy demonstrated to have potentiality in improving clinical outcomes and relieving major side effects of standard treatment options. In addition, given the distinctive features such as high safety, low toxicity effects on healthy cells, numerous clinical trials conducted on CIK cells. Due to the shortcomings that observed in CIK cell immunotherapy alone, arising a tendency to make modifications (combined modality therapy or combination therapy) including the addition of various types of cytokines, genetic engineering, combination with immune checkpoints, and so on. In this review, we have tried to bring forth the latest immunotherapy methods and their overview. We have discussed the combination therapies with CIK cells and the conducted clinical trials. This helps the future studies to use integrated therapies with CIK cells as a promising treatment of many types of cancers.

Dopamine alleviated acute liver injury induced by lipopolysaccharide/d-galactosamine in mice

Dopamine (DA), a crucial neurotransmitter, not only functions in the central nervous system but also plays important roles in the modulation of inflammation. Several studies suggest that DA might suppress the inflammatory response both in vitro and in vivo. In the present study, the potential effects of DA in a mouse model with lipopolysaccharide (LPS)/d-galactosamine (D-Gal)-induced acute liver injury were investigated. The results show that DA-treated LPS/D-Gal-exposed mice had reduced incidence of histologic lesions, lower plasma aminotransferases and improved the survival rates compared to LPS/D-Gal-exposed mice. Treatment with DA also suppressed LPS/D-Gal-induced production of TNF-α, phosphorylation of c-jun-N-terminal kinase (JNK), cleavage of caspase-3, up-regulation of hepatic caspase-3, caspase-8, and caspase-9 activities and reduced the count of TUNEL-positive hepatocytes. These data indicate that DA attenuated LPS/D-Gal-induced fulminant liver injury in mice, which implies that DA might have value for the prevention of inflammatory liver disease.

Anti-inflammatory properties of ursodeoxycholyl lysophosphatidylethanolamide in endotoxin-mediated inflammatory liver injury

AIM

Endotoxin-mediated liver inflammation is a key component of many acute and chronic liver diseases contributing to liver damage, fibrosis and eventually organ failure. Here, we investigated ursodeoxycholyl lysophosphatidylethanolamide (UDCA-LPE), a synthetic bile acid-phospholipid conjugate regarding its anti-inflammatory and anti-fibrogenic properties.

METHODS

Anti-inflammatory properties of UDCA-LPE were evaluated in a mouse model of D-galactosamine/lipopolysaccharide (GalN/LPS)-induced acute liver injury, LPS treated RAW264.7 macrophages and murine primary Kupffer cells. Furthermore, anti-inflammatory and anti-fibrotic effects of UDCA-LPE were studied on primary hepatic stellate cells (HSC) incubated with supernatant from LPS±UDCA-LPE treated RAW264.7 cells.

RESULTS

UDCA-LPE ameliorated LPS-induced increase of IL-6, TNF-α, TGF-β, NOX-2 in the GalN/LPS model by up to 80.2% for IL-6. Similarly, UDCA-LPE markedly decreased the expression of inflammatory cytokines IL-6, TNF-α and TGF-β as well as the chemokines MCP1 and RANTES in LPS-stimulated RAW 264.7 cells. Anti-inflammatory effects were also observed in primary murine Kupffer cells. Mechanistic evaluation revealed a reversion of LPS-activated pro-inflammatory TLR4 pathway by UDCA-LPE. Moreover, UDCA-LPE inhibited iNOS and NOX-2 expression while activating eNOS via phosphorylation of AKT and pERK1/2 in RAW264.7 cells. HSC treated with conditioned medium from LPS±UDCA-LPE RAW264.7 cells showed lower fibrogenic activation due to less SMAD2/3 phosphorylation, reduced expression of profibrogenic CTGF and reduced pro-inflammatory chemokine expression.

CONCLUSION

In the setting of endotoxin-mediated liver inflammation, UDCA-LPE exerts profound anti-inflammatory and anti-fibrotic effect implying a promising potential for the drug candidate as an experimental approach for the treatment of acute and chronic liver diseases.

Dietary α-Mangostin Provides Protective Effects against Acetaminophen-Induced Hepatotoxicity in Mice via Akt/mTOR-Mediated Inhibition of Autophagy and Apoptosis

Acetaminophen overdose-induced hepatotoxicity is the most common cause of acute liver failure in many countries. Previously, alpha-mangostin (α-MG) has been confirmed to exert protective effects on a variety of liver injuries, but the protective effect on acetaminophen-induced acute liver injury (ALI) remains largely unknown. This work investigated the regulatory effect and underlying cellular mechanisms of α-MG action to attenuate acetaminophen-induced hepatotoxicity in mice. The increased serum aminotransferase levels and glutathione (GSH) content and reduced malondialdehyde (MDA) demonstrated the protective effect of α-MG against acetaminophen-induced hepatotoxicity. In addition, α-MG pretreatment inhibited increases in tumor necrosis factor (TNF-α) and interleukin-1β (IL-1β) caused by exposure of mice to acetaminophen. In liver tissues, α-MG inhibited the protein expression of autophagy-related microtubule-associated protein light chain 3 (LC3) and BCL2/adenovirus E1B protein-interacting protein 3 (BNIP3). Western blotting analysis of liver tissues also proved evidence that α-MG partially inhibited the activation of apoptotic signaling pathways via increasing the expression of Bcl-2 and decreasing Bax and cleaved caspase 3 proteins. In addition, α-MG could in part downregulate the increase in p62 level and upregulate the decrease in p-mTOR, p-AKT and LC3 II /LC3 I ratio in autophagy signaling pathways in the mouse liver. Taken together, our findings proved novel perspectives that detoxification effect of α-MG on acetaminophen-induced ALI might be due to the alterations in Akt/mTOR pathway in the liver.

Crosstalk of liver immune cells and cell death mechanisms in different murine models of liver injury and its clinical relevance

BACKGROUND

Liver inflammation or hepatitis is a result of pluripotent interactions of cell death molecules, cytokines, chemokines and the resident immune cells collectively called as microenvironment. The interplay of these inflammatory mediators and switching of immune responses during hepatotoxic, viral, drug-induced and immune cell-mediated hepatitis decide the fate of liver pathology. The present review aimed to describe the mechanisms of liver injury, its relevance to human liver pathology and insights for the future therapeutic interventions.

DATA SOURCES

The data of mouse hepatic models and relevant human liver diseases presented in this review are systematically collected from PubMed, ScienceDirect and the Web of Science databases published in English.

RESULTS

The hepatotoxic liver injury in mice induced by the metabolites of CCl₄, acetaminophen or alcohol represent necrotic cell death with activation of cytochrome pathway, formation of reactive oxygen species (ROS) and mitochondrial damage. The Fas or TNF-alpha induced apoptotic liver injury was dependent on activation of caspases, release of cytochrome c and apoptosome formation. The ConA-hepatitis demonstrated the involvement of TRAIL-dependent necrotic/necroptotic cell death with activation of RIPK1/3. The alpha-GalCer-induced liver injury was mediated by TNF-alpha. The LPS-induced hepatitis involved TNF-alpha, Fas/FasL, and perforin/granzyme cell death pathways. The MHV3 or Poly(I:C) induced liver injury was mediated by natural killer cells and TNF-alpha signaling. The necrotic ischemia-reperfusion liver injury was mediated by hypoxia, ROS, and pro-inflammatory cytokines; however, necroptotic cell death was found in partial hepatectomy. The crucial role of immune cells and cell death mediators in viral hepatitis (HBV, HCV), drug-induced liver injury, non-alcoholic fatty liver disease and alcoholic liver disease in human were discussed.

CONCLUSIONS

The mouse animal models of hepatitis provide a parallel approach for the study of human liver pathology. Blocking or stimulating the pathways associated with liver cell death could unveil the novel therapeutic strategies in the management of liver diseases.

Establishment of a new acute-on-chronic liver failure model

To establish an animal model of acute-on-chronic liver failure (ACLF) that would replicate the pathological process of ACLF in humans, rats were administered porcine serum (PS) for 11 weeks. Liver fibrosis was determined by pathological and biochemical assessments. The animals then were injected with d-galactosamine (d-gal) and lipopolysaccharide (LPS). The survival times of animals with cirrhosis and ACLF were determined over 48 h. Other animals were killed at 0, 4, 8 and 12 h after administration of d-gal/LPS. Liver injury was assessed by histopathological analysis and biochemical indices, and apoptosis was detected by Western blot and TUNEL analysis. After PS administration for 11 weeks the serum levels of hyaluronic acid and N-procollagen type III peptide increased significantly, and serious fibrosis and cirrhosis was observed at weeks 10 and 11. Cirrhotic rats were injected with d-gal/LPS to induced ACLF; the rate of mortality over 48 h was 80%. ALT and AST levels increased markedly at 4 h, but decreased significantly at 8 and 12 h post-treatment. The total bilirubin, direct bilirubin, and total bile acids levels increased markedly at 8 and 12 h. Clotting times, TNF-α and IL-6 levels increased significantly, except for 12 h post-treatment. Apoptosis, inflammation and necrosis were elevated as determined by hematoxylin-eosin staining and TUNEL assays. BCL-2 levels decreased significantly, While BAX levels increased significantly. Cytochrome c expression peaked at 8 h post-d-gal/LPS treatment. In conclusion, an ACLF model induced by PS and d-gal/LPS was established and the underlying mechanisms of ACLF development were explored.

Intraportal mesenchymal stem cell transplantation prevents acute liver failure through promoting cell proliferation and inhibiting apoptosis

BACKGROUND

Transplantation of mesenchymal stem cells (MSCs) has been regarded as a potential treatment for acute liver failure (ALF), but the optimal route was unknown. The present study aimed to explore the most effective MSCs transplantation route in a swine ALF model.

METHODS

The swine ALF model induced by intravenous injection of D-Gal was treated by the transplantation of swine MSCs through four routes including intraportal injection (InP group), hepatic intra-arterial injection (AH group), peripheral intravenous injection (PV group) and intrahepatic injection (IH group). The living conditions and survival time were recorded. Blood samples before and after MSCs transplantation were collected for the analysis of hepatic function. The histology of liver injury was interpreted and scored in terminal samples. Hepatic apoptosis was detected by TUNEL assay. Apoptosis and proliferation related protein expressions including cleaved caspase-3, survivin, AKT, phospho-AKT (Ser473), ERK and phospho-ERK (Tyr204) were analyzed by Western blotting.

RESULTS

The average survival time of each group was 10.7+/-1.6 days (InP), 6.0+/-0.9 days (AH), 4.7+/-1.4 days (PV), 4.3+/-0.8 days (IH), respectively, when compared with the average survival time of 3.8+/-0.8 days in the D-Gal group. The survival rates between the InP group and D-Gal group revealed a statistically significant difference (P<0.01). Pathological and biochemical analysis showed that liver damage was the worst in the D-Gal group, while less injury in the InP group. Histopathological scores revealed a significant decrease in the InP group (3.17+/-1.04, P<0.01) and AH group (8.17+/-0.76, P<0.05) as compared with that in the D-Gal group (11.50+/-1.32). The apoptosis rate in the InP group (25.0%+/-3.4%, P<0.01) and AH group (40.5%+/-1.0%, P<0.05) was lower than that in the D-Gal group (70.6%+/-8.5%). The expression of active caspase-3 was inhibited, while the expression of survivin, AKT, phospho-AKT (Ser473), ERK and phospho-ERK (Tyr204) was elevated in the InP group.

CONCLUSIONS

Intraportal injection was superior to other pathways for MSC transplantation. Intraportal MSC transplantation could improve liver function, inhibit apoptosis and prolong the survival time of swine with ALF. The transplanted MSCs may participate in liver regeneration via promoting cell proliferation and suppressing apoptosis during the initial stage of ALF.

The effect of D-galactosamine on lean and steatotic rat hepatocytes in primary culture

The aim of our work was to compare the effect of D-galactosamine (GalN) on primary cultures of lean and steatotic rat hepatocytes isolated from intact and fatty liver, respectively. GalN caused more severe injury to steatotic hepatocytes than to lean cells as documented by lactate dehydrogenase leakage. Necrotic mode of cell death strongly prevails over apoptosis since we did not observe any significant increase in activities of caspase 3, 8 and 9 in any group of hepatocytes treated with GalN. Reactive oxygen species (ROS) formation and lipid peroxidation were elevated in a dose-dependent manner by GalN and were significantly more pronounced in fatty hepatocytes. A decrease in the percentage of hepatocytes with energized mitochondria was observed from 30 mM and 10 mM GalN in lean and steatotic hepatocytes, respectively. Our results undoubtedly indicate that steatotic hepatocytes exert higher sensitivity to the toxic effect of GalN. This sensitivity may be caused by more intensive GalN-induced ROS production and lipid peroxidation and by higher susceptibility of mitochondria to loss of mitochondrial membrane potential in steatotic hepatocytes. In our experimental arrangement, apoptosis does not seem to participate considerably on hepatotoxic action of GalN in either group of hepatocytes.

Recql5 protects against lipopolysaccharide/D-galactosamine-induced liver injury in mice

AIM: To investigate the effects of Recql5 deficiency on liver injury induced by lipopolysaccharide/D-galactosamine (LPS/D-Gal).

METHODS: Liver injury was induced in wild type (WT) or Recql5-deficient mice using LPS/D-Gal, and assessed by histological, serum transaminases, and mortality analyses. Hepatocellular apoptosis was quantified by transferase dUTP nick end labeling assay and Western blot analysis of cleaved caspase-3. Liver inflammatory chemokine and cytochrome P450 expression was analyzed by quantitative reverse transcription-PCR. Neutrophil infiltration was evaluated by myeloperoxidase activity. Expression and phosphorylation of ERK, JNK, p65, and H2A.X was determined by Western blot. Oxidative stress was evaluated by measuring malondialdehyde production and nitric oxide synthase, superoxide dismutase, glutathione peroxidase, catalase, and glutathione reductase activity.

RESULTS: Following LPS/D-Gal exposure, Recql5-deficient mice exhibited enhanced liver injury, as evidenced by more severe hepatic hemorrhage, higher serum aspartate transaminase and alanine transaminase levels, and lower survival rate. As compared to WT mice, Recql5-deficient mice showed an increased number of apoptotic hepatocytes and higher cleaved caspase-3 levels. Recql5-deficient mice exhibited increased DNA damage, as evidenced by increased γ-H2A.X levels. Inflammatory cytokine levels, neutrophil infiltration, and ERK phosphorylation were also significantly increased in the knockout mice. Additionally, Recql5-deficicent mice exhibited increased malondialdehyde production and elevated inducible nitric oxide synthase, superoxide dismutase, glutathione peroxidase, catalase, and glutathione reductase activity, indicative of enhanced oxidative stress. Moreover, CYP450 expression was significantly downregulated in Recql5-deficient mice after LPS/D-Gal treatment.

CONCLUSION: Recql5 protects the liver against LPS/D-Gal-induced injury through suppression of hepatocyte apoptosis and oxidative stress and modulation of CYP450 expression.

Understanding liver immunology using intravital microscopy

The liver has come a long way since it was considered only a metabolic organ attached to the gastrointestinal tract. The simultaneous ascension of immunology and intravital microscopy evidenced the liver as a central axis in the immune system, controlling immune responses to local and systemic agents as well as disease tolerance. The multiple hepatic cell populations are organized in a vascular environment that promotes intimate cellular interactions, including initiation of innate and adaptive immune responses, rapid leukocyte recruitment, pathogen clearance and production of a variety of immune mediators. In this review, we focus on the advances in liver immunology supported by intravital microscopy in diseases such as isquemia/reperfusion, acute liver injury and infections.

Protective effect of Salvia miltiorrhiza and Carthamus tinctorius extract against lipopolysaccharide-induced liver injury

AIM: To investigate the hepatoprotective effects and mechanisms of an extract of Salvia miltiorrhiza and Carthamus tinctorius in vivo.

METHODS: C57BL/6J mice were randomly assigned to five groups and intraperitoneally administered 0.9% saline, Salvia miltiorrhiza and Carthamus tinctorius extract [Danhong injection (DHI), 0.75 and 3 g/kg mixed extract] or reduced glutathione for injection (RGI, 300 mg/kg) for 30 min before exposure to lipopolysaccharide (LPS, 16 mg/kg). After intraperitoneal LPS stimulation for 90 min or 6 h, the mice were sacrificed by ether anaesthesia, and serum and liver samples were collected. Histological analysis (H&E) and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL) staining were performed. Alanine transferase (ALT), aspartate transaminase (AST), total bilirubin (TBil), glutathione-S-transferase (GST), malondialdehyde (MDA), tumour necrosis factor (TNF)-α, interleukin (IL)-6, and caspase-3 levels were measured. Bax, Bcl-2, P-IκBα, IκBα, P-NF-κB p65, and NF-κB p65 protein levels were determined by Western blot. TNF-α, IL-6, caspase-3, Bax and Bcl-2 mRNA expression was measured by real-time reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS: Hematoxylin-eosin staining and TUNEL results suggested that DHI (3 g/kg) treatment alleviated inflammatory and apoptotic (P < 0.01) injury in the liver of mice. DHI treatment dose-dependently blunted the abnormal changes in biochemical parameters such as ALT (72.53 ± 2.83 for 3 g/kg, P < 0.01), AST (76.97 ± 5.00 for 3 g/kg, P < 0.01), TBil (1.17 ± 0.10 for 3 g/kg, P < 0.01), MDA (0.81 ± 0.36 for 3 g/kg, P < 0.01), and GST (358.86 ± 12.09 for 3 g/kg, P < 0.01). Moreover, DHI (3 g/kg) remarkably decreased LPS-induced protein expression of TNF-α (340.55 ± 10.18 for 3 g/kg, P < 0.01), IL-6 (261.34 ± 10.18 for 3 g/kg, P < 0.01), and enzyme activity of caspase-3 (0.93 ± 0.029 for 3 g/kg, P < 0.01). The LPS-induced mRNA expression of TNF-α, IL-6 and caspase-3 was also decreased by DHI. Western blot analysis revealed that DHI antagonised LPS-stimulated decrease of Bcl-2 and increase of Bax protein expression. Furthermore, DHI inhibited LPS-induced IκBα and NF-κB p65 phosphorylation.

CONCLUSION: DHI may be a multi-function protectant against acute hepatic injury in mice through its anti-inflammatory, anti-oxidative and anti-apoptotic activities.

Acute liver injury attenuation of a novel recombinant sTNFR through blocking hepatic apoptosis

CONTEXT

Tumor necrosis factor (TNF) α plays a key role in acute liver injury (ALI) induced by injection of d-galactosamine (D-Gal)/lipopolysaccharide (LPS). A novel recombinant trimeric sTNFRII, sTNFRII-gAD, has been tested to be effective in ameliorating ALI, when administered prior to ALI establishment. This study aims to validate the protective effect of sTNFRII-gAD when given after ALI setup and further explore its effect on hepatic apoptosis.

MATERIALS AND METHODS

The treatments were carried out concomitantly with ALI establishment with clinically approved sTNFRII-Fc (the dimeric sTNFRII) as a positive control. Lethality, liver weight, and serum alanine transaminase were measured, and histological analysis was performed to evaluate liver injury induced by D-Gal/LPS. Additionally, Terminal-deoxynucleoitidyl transferase-mediated nick end labeling (TUNEL) and Western blot analyses of caspase-3 were used to examine hepatocellular apoptosis.

RESULTS

sTNFRII-gAD given after D-Gal/LPS injection turned out to attenuate animal mortality significantly (p < 0.01), and had better hepatic protection. In terms of apoptosis, both sTNFRII-gAD and sTNFRII-Fc displayed noticeable improvement of apoptosis evidenced by dramatic decline of active caspase-3 compared to the control group.

CONCLUSIONS

The results demonstrated that sTNFRII-gAD therapeutically diminished the lethality induced by D-Gal/LPS, possibly through blocking hepatic apoptosis initiated by TNFα. Of note, sTNFRII-gAD was superior to sTNFRII-Fc in some respects, indicating a promising alternative for the therapeutic strategy against the diseases associated with excessive TNFα.

Autocrine DNA fragmentation of intra-epithelial lymphocytes (IELs) in mouse small intestine

Intraepithelial lymphocytes (IELs) are present in the intestinal epithelium. Mechanisms of IELs for the protection of villi from foreign antigens and from infections by micro-organisms have not been sufficiently explained. Although more than 70% of mouse duodenal and jejunal IELs bear γδTCR (γδIELs), the functions of γδIELs are little investigated. We stimulate γδIELs by anti-CD3 monoclonal antibody (mAb) injection. The mAb activates γδIELs to release Granzyme B (GrB) into the spaces surrounding the γδIELs and intestinal villous epithelial cells (IECs). Released GrB induces DNA fragmentation in IECs independently of Perforin (Pfn). IECs immediately repair their fragmented DNA. Activated IELs reduce their cell size, remain for some time in the epithelium after the activation and are ultimately eliminated without leaving the site. We focus our attention on the response of IELs to the released GrB present in the gap surrounding IELs, after activation, in order to examine whether the released GrB has a similar effect on IELs to that observed on IECs in our previous studies. DNA fragmentation is also induced in IELs together with the repair of fragmented DNA thereafter. The time-kinetics of both events were found to be identical to those observed in IECs. DNA fragmentation in IELs is Pfn-independent. Here, we present Pfn-independent "autocrine DNA fragmentation" in IELs and the repair of fragmented DNA in IELs and discuss their biological significance. Autocrine DNA fragmentation has never been reported to date in vivo.

The brain in acute on chronic liver failure

Acute-on-chronic liver failure (ACLF) is a newly defined clinical entity with significant morbidity and mortality (~40-90% at 1 year dependent on need for organ support at presentation). It defines a presentation with acute severe liver injury, often with multiorgan dysfunction, on a background of previously known or unknown cirrhosis. In its severest form, it is almost indistinguishable from acute liver failure, as similarly in around 5% may rapidly progress to intracranial hypertension and cerebral oedema culminating in coma and/or death. Our understanding of such cerebral sequelae is currently limited to clinical observation, though our knowledge base is rapidly expanding since recent consensus clinical definition and guidance. Moreover, there are now animal models of ACLF and imaging modalities to better characterize events in the brain that occur with ACLF. However, as yet there has been little in the way of interventional study of this condition which are much needed. In this review we dissect existing clinical and experimental data to better characterise the manifestations of ACLF on the brain and allow for the development of targeted therapy as currently the plethora of existing interventions were designed to treat either the effects of cirrhosis or acute liver injury independently.

The liver protective effect of methylprednisolone on a new experimental acute-on-chronic liver failure model in rats

BACKGROUND

Acute-on-chronic liver failure is a severe, life-threatening entity and the comprehension of this disease is incomplete. Currently, a reasonable surgical model of acute-on-chronic liver failure is still lacking. The aim of this study was to establish a new model of acute-on-chronic liver failure in rats and to investigate the protective effects of methylprednisolone on this model.

METHODS

An obstructive jaundice model in rats was established. Two weeks later, the animals were subjected to a choledochoduodenostomy and a reduced-size hepatic ischaemia/reperfusion injury. Animals were randomly divided into a control group, a methylprednisolone injected via the tail vein group and a methylprednisolone injected via the portal vein group. The survival rates and serum levels of alanine transaminase, aspartate aminotransferase, total bilirubin, tumour necrosis factor alpha, and interferon gamma of the rats were measured and the pathological changes in liver tissues were observed.

RESULTS

The survival rate was significantly improved in the methylprednisolone treatment groups. Serum levels of the biochemical indexes were the lowest in the portal vein injection group. Liver tissues under microscopy presented severe pathological injury in the control group.

CONCLUSION

This model could be useful for further research into acute-on-chronic liver failure and methylprednisolone may be a potential therapeutic agent for this disease.

Hepatoprotective effects of erythropoietin on D-galactosamine/lipopolysaccharide-induced fulminant hepatic failure in mice

Fulminant hepatic failure is a severe clinical syndrome associated with a high rate of patient mortality. Recent studies have shown that in addition to its hematopoietic effect, erythropoietin (EPO) has multiple protective effects and exhibits antiapoptotic, antioxidant and anti-inflammatory activities. The present study aimed to determine the hepatoprotective effect of EPO and to elucidate the underlying mechanisms using a D-galactosamine (D-GalN)/lipopolysaccharide (LPS)-induced model of acute liver injury. Experimental groups of mice were administered with various doses of EPO (1,000, 3,000 or 10,000 U/kg, intraperitoneal) once per day for 3 days, prior to injection with D-GalN (700 mg/kg)/LPS (10 µg/kg). Mice were sacrificed 8 h after treatment with D‑GalN/LPS. Liver function and histopathology, malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH‑Px) activities and EPO receptor (EPOR) and phosphatidylinositol 3-kinase (PI3K) mRNA expression were evaluated. D-GalN/LPS administration markedly induced liver injury, as evidenced by elevated levels of serum aminotransferases, as well as histopathological changes. Compared with the D-GalN/LPS group, pretreatment with EPO significantly decreased the levels of aspartate aminotransferase, alanine aminotransferase and MDA, and increased the activities of SOD and GSH-Px. Furthermore, the protective effects of EPO were paralleled by an upregulation in the mRNA expression of EPOR and PI3K. These data suggest that EPO can ameliorate D-GalN/LPS-induced acute liver injury by reducing oxidative stress and upregulating the mRNA expression of EPOR and PI3K.

Protective effects of garcinol in mice with lipopolysaccharide/D-galactosamine-induced apoptotic liver injury

Garcinol is a polyisoprenylated benzophenone derivative of Garcinia indica. Recent researches have revealed the antioxidant, anticancer and anti-inflammatory properties of garcinol. In the present study, the pharmacological effects of garcinol in lipopolysaccharide (LPS)-induced hepatic injury in D-galactosamine (D-Gal)-sensitized mice were investigated. We found that treatment with garcinol significantly decreased serum ALT and AST levels in LPS/D-Gal-exposed mice. These were accomplished with improved histological alterations in liver sections and reduced malondialdehyde (MDA) content in liver homogenates. Garcinol significantly reduced the acetylation level of NF-κB, but it had no obvious effects on the elevation of TNF-α or IL-6 in plasma or liver tissue. Garcinol significantly attenuated LPS/D-Gal-induced hepatic apoptosis as evidenced by reduced number of TUNEL-positive cells in liver sections. Our experiments also showed that garcinol markedly suppressed the cleavage of caspase-3 and significantly decreased the activities of caspase-3, -8, and -9 in liver tissues. In addition, garcinol obviously reduced the induction of Bax but did not alter the level of Bcl-2. These results indicated that garcinol might provide protective benefits in LPS/D-Gal-induced liver injury through suppressing apoptosis.

Life cycle and pathogenesis of hepatitis D virus: A review

Hepatitis D virus (HDV) is a defective RNA virus which requires the help of hepatitis B virus (HBV) virus for its replication and assembly of new virions. HDV genome contains only one actively transcribed open reading frame which encodes for two isoforms of hepatitis delta antigen. Post-translational modifications of small and large delta antigens (S-HDAg and L-HDAg) involving phosphorylation and isoprenylation respectively confer these antigens their specific properties. S-HDAg is required for the initiation of the viral genome replication, whereas L-HDAg serves as a principal inhibitor of replication and is essential for the assembly of new virion particles. Immune mediation has usually been implicated in HDV-associated liver damage. The pathogenesis of HDV mainly involves interferon-α signaling inhibition, HDV-specific T-lymphocyte activation and cytokine responses, and tumor necrosis factor-alpha and nuclear factor kappa B signaling. Due to limited protein coding capacity, HDV makes use of host cellular proteins to accomplish their life cycle processes, including transcription, replication, post-transcriptional and translational modifications. This intimate host-pathogen interaction significantly alters cell proteome and is associated with an augmented expression of pro-inflammatory, growth and anti-apoptotic factors which explains severe necroinflammation and increased cell survival and an early progression to hepatocellular carcinoma in HDV patients. The understanding of the process of viral replication, HBV-HDV interactions, and etio-pathogenesis of the severe course of HDV infection is helpful in identifying the potential therapeutic targets in the virus life cycle for the prophylaxis and treatment of HDV infection and complications.

The inhibitory action of PDCD4 in lipopolysaccharide/D-galactosamine-induced acute liver injury

Programmed cell death 4 (PDCD4) acts as a tumor suppressor gene, which suppresses tumor growth, infiltration and metastasis. Our previous studies demonstrated that PDCD4 had an important role in the development of ovarian cancer and glioma. Recent studies show that PDCD4 is also involved in various inflammatory diseases. However, its exact effect on inflammation remains unclear. In our current study, we explored the role of PDCD4 in acute liver injury induced by lipopolysaccharide (LPS) and D-galactosamine (D-GalN) using wild-type (WT) mice and PDCD4-deficient mice. Our results showed that liver-to-body weight ratios, as well as serum aspartate transaminase (AST) and alanine transaminase (ALT) levels were significantly increased in PDCD4-deficient mice than WT mice. Histological examination, immunohistochemical and TUNEL analysis revealed PDCD4-deficient mice had more necrotic and apoptotic hepatocytes, inflammatory cells infiltration and liver internal hemorrhage than WT mice. In addition, some inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) in the serum and liver tissues were also significantly increased in PDCD4-deficient mice. More importantly, we found that the aggravation of liver tissue injury in PDCD4-deficient mice was due to excessive mitogen-activated protein kinase and NF-κB activation, which induced the release of more inflammatory factors, and consequently resulted in higher levels of hepatocyte necrosis and apoptosis. These results indicate that PDCD4 has a protective role in LPS/D-GalN-induced acute liver injury. This finding may present new opportunities for PDCD4 to be explored as a therapeutic target in acute liver injury.

Granzyme B-dependent and perforin-independent DNA fragmentation in intestinal epithelial cells induced by anti-CD3 mAb-activated intra-epithelial lymphocytes

We previously found that an i.p. injection of anti-CD3 monoclonal antibody (mAb) into mice caused DNA fragmentation in the intestinal villous epithelial cells (IVECs) of the duodenum and the jejunum. In this study, in order to elucidate the mechanism of DNA fragmentation in IVECs, we searched for the inducer(s) of DNA fragmentation by using immunohistochemistry. The release of cytoplasmic granules from intraepithelial lymphocytes (IELs) and the formation of large gaps between IELs and IVECs were observed electron microscopically after antibody administration. The presence and distribution pattern of Granzyme B (GrB), a serine protease in cytolytic granules present in cytotoxic T lymphocytes and natural killer cells and considered to be the responsible molecule for DNA fragmentation in target cells, was examined in detail in intestinal villi by immunohistology. GrB was detected in cytoplasmic granules in nearly all IELs. The time-kinetics of granule release from IELs after mAb injection coincided not only with that of the extracellular diffusion of GrB, but also with that of DNA fragmentation in IVECs. On the other hand, perforin (Pfn), assumed to cooperate with GrB in DNA fragmentation, could not be detected in IELs, and its release was not confirmed after the anti-CD3 mAb injection. Anti-CD3 mAb injection also induced DNA fragmentation in IVECs in Pfn-knockout mice. These results support the notion that DNA fragmentation in IVECs by the stimulated IELs in the present study is induced by a mechanism involving GrB, but independent of Pfn.

Ethyl pyruvate protects against experimental acute-on-chronic liver failure in rats

AIM: To investigate the protective effects of ethyl pyruvate (EP) on acute-on-chronic liver failure (ACLF) in rats.

METHODS: An ACLF model was established in rats, and animals were randomly divided into normal, model and EP treatment groups. The rats in EP treatment group received EP (40 mg/kg) at 3 h, 6 h, 12 h and 24 h after induction of ACLF. Serum endotoxin, high mobility group box-1 (HMGB1), alanine transaminase (ALT), tumor necrosis factor-α (TNF-α), interferon-α (IFN-γ), interleukin (IL)-10 and IL-18 levels, changes of liver histology and HMGB1 expressions in liver tissues were detected at 48 h after induction of ACLF. The effects of EP on the survival of ACLF rats were also observed.

RESULTS: Serum levels of endotoxin (0.394 ± 0.066 EU/mL vs 0.086 ± 0.017 EU/mL, P < 0.001), HMGB1 (35.42 ± 10.86 μg/L vs 2.14 ± 0.27 μg/L, P < 0.001), ALT (8415.87 ± 3567.54 IU/L vs 38.64 ± 8.82 IU/L, P < 0.001), TNF-α (190.77 ± 12.34 ng/L vs 124.40 ± 4.12 ng/L, P < 0.001), IFN-γ (715.38 ± 86.03 ng/L vs 398.66 ± 32.91 ng/L, P < 0.001), IL-10 (6.85 ± 0.64 ng/L vs 3.49 ± 0.24 ng/L, P < 0.001) and IL-18 (85.19 ± 3.49 ng/L vs 55.38 ± 1.25 ng/L, P < 0.001) were significantly increased, and liver tissues presented severe pathological injury in the model group compared with the normal group. However, EP administration significantly improved hepatic histopathology and reduced the serum levels of endotoxin (0.155 ± 0.045 EU/mL vs 0.394 ± 0.066 EU/mL, P < 0.001) and inflammatory cytokines (11.13 ± 2.58 μg/L vs 35.42 ± 10.86 μg/L for HMGB1, 3512.86 ± 972.67 IU/L vs 8415.87 ± 3567.54 IU/L for ALT, 128.55 ± 5.76 ng/L vs 190.77 ± 12.34 ng/L for TNF-α, 438.16 ± 38.10 ng/L vs 715.38 ± 86.03 ng/L for IFN-γ, 3.55 ± 0.36 ng/L vs 6.85 ± 0.64 ng/L for IL-10, and 60.35 ± 1.63 ng/L vs 85.19 ± 3.49 ng/L for IL-18, respectively, P < 0.001), and the levels of HMGB1 in liver tissues regardless of treatment time after induction of ACLF. EP treatment at the four time points prolonged the median survival time of ACLF rats (60 h) to 162 h, 120 h, 102 h and 78 h, respectively (χ² = 41.17, P < 0.0001).

CONCLUSION: EP administration can protect against ACLF in rats, and is a potential and novel therapeutic agent for severe liver injury.

Feeder-free and serum-free production of hepatocytes, cholangiocytes, and their proliferating progenitors from human pluripotent stem cells: application to liver-specific functional and cytotoxic assays

We have established a serum- and feeder-free culture system for the efficient differentiation of multifunctional hepatocytes from human embryonic stem (ES) cells and three entirely different induced pluripotent stem (iPS) cells (including vector/transgene-free iPS cells generated using Sendai virus vector) without cell sorting and gene manipulation. The differentiation-inducing protocol consisted of a first stage; endoderm induction, second stage; hepatic initiation, and third stage; hepatic maturation. At the end of differentiation culture, hepatocytes induced from human pluripotent stem cells expressed hepatocyte-specific proteins, such as α-fetoprotein, albumin, α1 antitrypsin and cytochrome P450 (CYP3A4), at similar or higher levels compared with three control human hepatocyte or hepatic cell lines. These human iPS/ES cell-derived hepatocytes also showed mature hepatocyte functions: indocyanine green dye uptake (≈ 30%), storage of glycogen (>80%) and metabolic activity of CYP3A4. Furthermore, they produced a highly sensitive hepatotoxicity assay system for D-galactosamine as determined by the extracellular release of hepatocyte-specific enzymes. Hepatoprotective prostaglandin E1 attenuated this toxicity. Interestingly, bile duct-specific enzymes were also detected after drug treatment, suggesting the presence of bile-duct epithelial cells (cholangiocytes) in our culture system. Electron microscopic studies confirmed the existence of cholangiocytes, and an immunostaining study proved the presence of bipotential hepatoblasts with high potential for proliferation. Differentiated cells were transferrable onto new dishes, on which small-sized proliferating cells with hepatocyte markers emerged and expanded. Thus, our differentiation culture system provides mature functional hepatocytes, cholangiocytes, and their progenitors with proliferative potential from a wide variety of human pluripotent stem cells.

Complement and the alternative pathway play an important role in LPS/D-GalN-induced fulminant hepatic failure

Fulminant hepatic failure (FHF) is a clinically severe type of liver injury with an extremely high mortality rate. Although the pathological mechanisms of FHF are not well understood, evidence suggests that the complement system is involved in the pathogenesis of a variety of liver disorders. In the present study, to investigate the role of complement in FHF, we examined groups of mice following intraperitoneal injection of LPS/D-GalN: wild-type C57BL/6 mice, wild-type mice treated with a C3aR antagonist, C5aR monoclonal antibody (C5aRmAb) or CR2-Factor H (CR2-fH, an inhibitor of the alternative pathway), and C3 deficient mice (C3⁻/⁻ mice). The animals were euthanized and samples analyzed at specific times after LPS/D-GalN injection. The results show that intraperitoneal administration of LPS/D-GalN activated the complement pathway, as evidenced by the hepatic deposition of C3 and C5b-9 and elevated serum levels of the complement activation product C3a, the level of which was associated with the severity of the liver damage. C3a receptor (C3aR) and C5a receptor (C5aR) expression was also upregulated. Compared with wild-type mice, C3⁻/⁻ mice survived significantly longer and displayed reduced liver inflammation and attenuated pathological damage following LPS/D-GalN injection. Similar levels of protection were seen in mice treated with C3aR antagonist,C5aRmAb or CR2-fH. These data indicate an important role for the C3a and C5a generated by the alternative pathway in LPS/D-GalN-induced FHF. The data further suggest that complement inhibition may be an effective strategy for the adjunctive treatment of fulminant hepatic failure.

Acute liver failure: mechanisms of immune-mediated liver injury

Acute liver failure (ALF) is a syndrome of diverse aetiology, including hepatic encephalopathy, renal, cardiac and pulmonary failures, which result in a rapid loss of hepatic function. The mechanisms of liver injury contributing to ALF can be summarized into two categories: direct damage and immune-mediated liver injury. This review summarizes current concepts of immune-mediated liver injury from both clinical studies and animal models. We highlight immune responses of ALF from the liver injury perspective, which combines a variety of molecular and cellular mechanisms, particularly, the contribution of cytokines and the innate immune system. Hepatic and circulating inflammatory cytokines play a significant role in the pathophysiology of ALF including hepatocyte necrosis, extrahepatic complications and hepatocyte regeneration. Overproduction of cytokines, if unchecked, is hazardous to the host and may cause severe outcomes. Measuring pro-inflammatory cytokines in ALF may be of value for predictors of outcome. Innate and adaptive immune systems both involved in ALF contribute to immune-mediated liver injury. The innate immune response is activated much more rapidly compared with adaptive immunity, particularly in acute liver injury where the host has little time to trigger an effective adaptive immune response. From this point of view, the innate immune system may make a more profound contribution than the adaptive immune system. Furthermore, immune responses crosstalk with other physiological or pathophysiological factors, for example, coagulation factors which in turn determine the outcome of ALF and these are discussed.