Endotoxin tolerance ameliorates lipopolysaccharide/D-galactosamine-induced acute liver failure by negative regulation of the NF-κB/NLRP3 and activation of Nrf2/HO-1 via Sitr1

Acute liver failure (ALF) is a potentially fatal disorder characterized by extensive hepatocyte necrosis and rapid decline in liver function. Numerous factors, including oxidative stress, cell death, and inflammatory responses, are associated with its pathogenesis. Endotoxin tolerance (ET) refers to the phenomenon in which the body or cells exhibit low or no response to high-dose lipopolysaccharide (LPS) stimulation after pre-stimulation with low-dose LPS. However, the specific mechanism through which ET regulates LPS/D-galactosamine (D-GalN)-induced ALF remains unclear. An ALF mouse model was established by intraperitoneal injection of D-GalN (400 mg/kg) and LPS (10 mg/kg). A low dose of LPS (0.1 mg/kg/d) was continuously administered to mice for 5 d before modeling to assess the protective effect of ET. The data from this study showed that ET alleviated the inflammatory response in mice with LPS/D-GalN-induced ALF. ET inhibited LPS-induced oxidative damage and pyroptosis in macrophages in vitro. RNA sequencing analysis showed that the NF-κB/NLRP3 pathway was linked to the anti-inflammatory and antioxidative effects of ET. Furthermore, using western blot, RT-qPCR, and immunofluorescence, we verified that ET inhibited the NF-κB/NLRP3 pathway and triggered the Nrf2/HO-1 signaling pathway to attenuate oxidative stress and cell pyroptosis. Sirt1 knockdown reversed this protective effect. In summary, our research elucidates that ET prevents ALF advancement by upregulating Sirt1 levels, triggering the Nrf2/HO-1 signaling axis, and suppressing the NF-κB/NLRP3 signaling cascade to inhibit oxidative stress and cell pyroptosis. Our results provide a mechanistic explanation for the protective effect of ET against ALF.

New Insights into the Role of the Complement System in Human Viral Diseases

The complement system (CS) is part of the human immune system, consisting of more than 30 proteins that play a vital role in the protection against various pathogens and diseases, including viral diseases. Activated via three pathways, the classical pathway (CP), the lectin pathway (LP), and the alternative pathway (AP), the complement system leads to the formation of a membrane attack complex (MAC) that disrupts the membrane of target cells, leading to cell lysis and death. Due to the increasing number of reports on its role in viral diseases, which may have implications for research on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), this review aims to highlight significant progress in understanding and defining the role of the complement system in four groups of diseases of viral etiology: (1) respiratory diseases; (2) acute liver failure (ALF); (3) disseminated intravascular coagulation (DIC); and (4) vector-borne diseases (VBDs). Some of these diseases already present a serious global health problem, while others are a matter of concern and require the collaboration of relevant national services and scientists with the World Health Organization (WHO) to avoid their spread.

Isoliquiritigenin alleviates LPS/ D-GalN-induced acute liver failure by activating the PGC-1α/ Nrf2 pathway to reduce oxidative stress and inflammatory response

Acute liver failure (ALF) is a dramatic liver disease characterized by large areas of inflammation. However, there are no available effective targeted drugs for ALF treatment. In the study, serum biochemical index and H&E were used to explore the amelioration of the liver histopathological changes. The oxidative stress kits, quantitative real-time PCR, western blot, immunohistochemistry, immunofluorescence staining, reactive oxygen species (ROS), and siRNA were used to elucidate the mechanisms underlying isoliquiritigenin (ISL) protection. The results showed that ISL significantly improved the liver pathological changes. Furthermore, ISL reduced oxidative stress by altering the expression of PGC-1α, Nrf2, HO-1, NQO1, Keap1, GCLC, and GCLM in damaged hepatocytes. Moreover, the levels of inflammation-related genes including NLRP3 inflammasome, IL-1β, IL-6, TNF-α, iNOS, and Mip-2 were repressed by ISL. In addition, ISL alleviated LPS/D-GalN-induced hepatocytes apoptosis by increasing the Bcl-2/Bax ratio and suppressing the expression of cleaved caspase-3. Further in vivo and in vitro evidence proved the involvement of the PGC-1α/Nrf2 signaling pathway in ISL protection. In conclusion, ISL improves the ability of anti-oxidative stress, alleviates inflammatory reaction, apoptosis, and inhibits NLRP3 inflammasome to protect lipopolysaccharide/D-galactosamine (LPS/D-GalN)-induced ALF through activating the PGC-1α/Nrf2 pathway, which provides the possibility for the treatment of ALF.

AIRE Gene Mutation Presenting at Age 2 Years With Autoimmune Retinopathy and Steroid-Responsive Acute Liver Failure: A Case Report and Literature Review

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare monogenic autosomal recessive disorder caused by mutation in the autoimmune regulator (AIRE) gene. Patients usually are diagnosed at ages between 5 and 15 years when they show 3 or more manifestations, most typically mucocutaneous candidiasis, Addison's disease, and hypoparathyroidism. APECED-associated hepatitis (APAH) develops in only 10% to 40% of patients, with severity varying from subclinical chronic active hepatitis to potentially fatal acute liver failure (ALF). Ocular abnormalities are fairly common, most often keratopathy but sometimes retinopathy. Here we report a 2-year-old Japanese girl with an AIRE gene mutation who developed APAH with ALF, preceded by autoimmune retinopathy associated with anti-recoverin antibody before major symptoms suggested a diagnosis of APECED. Intravenous pulse methylprednisolone therapy followed by a corticosteroid combined with azathioprine treatment resolved ALF and achieved control of APAH. To our knowledge, our patient is the youngest reported to have ALF resulting from an AIRE gene mutation. Pulse methylprednisolone induction therapy followed by treatment with corticosteroid plus azathioprine may well be effective in other children with APAH and AIRE gene mutations.

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

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

TNF-α/HMGB1 inflammation signalling pathway regulates pyroptosis during liver failure and acute kidney injury

OBJECTIVE

Acute kidney injury (AKI) is a common complication of acute liver failure (ALF). Pyroptosis is a necrosis type related to inflammation. This study aimed to investigate the role of TNF-α/HMGB1 pathway in pyroptosis during ALF and AKI.

METHODS

An ALF and AKI mouse model was generated using LPS/D-Gal, and a TNF-α inhibitor, CC-5013, was used to treat the mice. THP-1 cells were induced to differentiate into M1 macrophages, then challenged with either CC-5013 or an HMGB1 inhibitor, glycyrrhizin. pLVX-mCMVZsGreen-PGK-Puros plasmids containing TNF-α wild-type (WT), mutation A94T of TNF-α and mutation P84L of TNF-α were transfected into M1 macrophages.

RESULTS

Treatment with CC-5013 decreased the activation of TNF-α/HMGB1 pathway and pyroptosis in the treated mice and cells compared with the control mice and cells. CC-5013 also ameliorated liver and kidney pathological changes and improved liver and renal functions in treated mice, and the number of M1 macrophages in the liver and kidney tissues also decreased. The activation of TNF-α/HMGB1 pathway and pyroptosis increased in the M1 macrophage group compared with the normal group. Similarly, the activation of TNF-α/HMGB1 pathway and pyroptosis in the LPS + WT group also increased. By contrast, the activation of the TNF-α/HMGB1 pathway and pyroptosis decreased in the LPS + A94T and LPS + P84L groups. Moreover, glycyrrhizin inhibited pyroptosis.

CONCLUSION

The TNF-α/HMGB1 inflammation signalling pathway plays an important role in pyroptosis during ALF and AKI.

Gasdermin D-mediated hepatocyte pyroptosis expands inflammatory responses that aggravate acute liver failure by upregulating monocyte chemotactic protein 1/CC chemokine receptor-2 to recruit macrophages

BACKGROUND

Massive hepatocyte death is the core event in acute liver failure (ALF). Gasdermin D (GSDMD)-mediated pyroptosis is a type of highly inflammatory cell death. However, the role of hepatocyte pyroptosis and its mechanisms of expanding inflammatory responses in ALF are unclear.

AIM

To investigate the role and mechanisms of GSDMD-mediated hepatocyte pyroptosis through in vitro and in vivo experiments.

METHODS

The expression of pyroptosis pathway-associated proteins in liver tissues from ALF patients and a hepatocyte injury model was examined by Western blot. GSDMD short hairpin RNA (shRNA) was used to investigate the effects of downregulation of GSDMD on monocyte chemotactic protein 1 (MCP1) and its receptor CC chemokine receptor-2 (CCR2) in vitro. For in vivo experiments, we used GSDMD knockout mice to investigate the role and mechanism of GSDMD in a D-galactose/lipopolysaccharide (D-Galn/LPS)-induced ALF mouse model.

RESULTS

The levels of pyroptosis pathway-associated proteins in liver tissue from ALF patients and a hepatocyte injury model increased significantly. The level of GSDMD-N protein increased most obviously (P < 0.001). In vitro, downregulation of GSDMD by shRNA decreased the cell inhibition rate and the levels of MCP1/CCR2 proteins (P < 0.01). In vivo, GSDMD knockout dramatically eliminated inflammatory damage in the liver and improved the survival of D-Galn/LPS-induced ALF mice (P < 0.001). Unlike the mechanism of immune cell pyroptosis that involves releasing interleukin (IL)-1β and IL-18, GSDMD-mediated hepatocyte pyroptosis recruited macrophages via MCP1/CCR2 to aggravate hepatocyte death. However, this pathological process was inhibited after knocking down GSDMD.

CONCLUSION

GSDMD-mediated hepatocyte pyroptosis plays an important role in the pathogenesis of ALF, recruiting macrophages to release inflammatory mediators by upregulating MCP1/CCR2 and leading to expansion of the inflammatory responses. GSDMD knockout can reduce hepatocyte death and inflammatory responses, thus alleviating ALF.

Hepatitis B virus infection: Defective surface antigen expression and pathogenesis

Hepatitis B virus (HBV) infection is a global public health concern. HBV causes chronic infection in patients and can lead to liver cirrhosis, hepatocellular carcinoma, and other severe liver diseases. Thus, understanding HBV-related pathogenesis is of particular importance for prevention and clinical intervention. HBV surface antigens are indispensable for HBV virion formation and are useful viral markers for diagnosis and clinical assessment. During chronic HBV infection, HBV genomes may acquire and accumulate mutations and deletions, leading to the expression of defective HBV surface antigens. These defective HBV surface antigens have been found to play important roles in the progression of HBV-associated liver diseases. In this review, we focus our discussion on the nature of defective HBV surface antigen mutations and their contribution to the pathogenesis of fulminant hepatitis B. The relationship between defective surface antigens and occult HBV infection are also discussed.

Monocyte human leukocyte antigen - Antigen D related, neutrophil oxidative burst and cytokine analysis in patients of decompensated cirrhosis with and without acute-on chronic liver failure

Background and aim

Due to a dysregulated immune response, patients with acute-on-chronic liver failure (ACLF) have increased risk of infection and multi organ failure in comparison to compensated cirrhosis. The comparative data on the presence of ‘immune paresis’ in patients with ACLF and decompensated cirrhosis without ACLF is not available. Aim of the present study was to compare the immunological parameters in patients with decompensated cirrhosis with and without ACLF.

Methodology

In a prospective study, 76 patients with decompensated cirrhosis with (n = 38) and without (n = 38) ACLF and 10 healthy controls (HC) were evaluated for monocytic human leukocyte antigen–antigen D Related (HLA-DR) expression, mean density of HLA-DR expressed on the surface of these cells, neutrophil oxidative burst (NOB) capacity and serum levels of cytokines (IL-1, IL-6, IL-8, IL10, IL-12, and TNF-α).

Results

Patients of decompensated cirrhosis with and without ACLF demonstrated significantly lower mean percentage of monocytes expressing HLA-DR and quantitative increase in the NOB after stimulation with PMA when compared to HC. However there was no difference in mean percentage of monocytes with HLA-DR expression (43.61±26.56% vs. 43.10±20.98%) (p = 0.91), mean density of HLA-DR expression on the surface (30.34±29.32 vs. 41.71±52.13) (p = 0.42) and quantitative increase in NOB after stimulation with PMA (16.55±11.91 vs. 17.24±16.18) (p = 0.47) amongst patients with decompensated cirrhosis with and without ACLF. Patients with ACLF had significantly higher pro-inflammatory and anti-inflammatory cytokines in comparison to patients with decompensated cirrhosis without ACLF.

Conclusion

Patients with decompensated cirrhosis demonstrate a component of immune-paresis, however there is similar impairment in HLA–DR expression and NOB capacity in patients with and without ACLF. Both inflammatory and anti-inflammatory cytokines are increased in patients with ACLF in comparison to patients with decompensated cirrhosis without ACLF.

Mesenchymal stem cells rescue acute hepatic failure by polarizing M2 macrophages

AIM

To investigate whether M1 or M2 polarization contributes to the therapeutic effects of mesenchymal stem cells (MSCs) in acute hepatic failure (AHF).

METHODS

MSCs were transfused into rats with AHF induced by D-galactosamine (DGalN). The therapeutic effects of MSCs were evaluated based on survival rate and hepatocyte proliferation and apoptosis. Hepatocyte regeneration capacity was evaluated by the expression of the hepatic progenitor surface marker epithelial cell adhesion molecule (EpCAM). Macrophage polarization was analyzed by M1 markers [CD68, tumor necrosis factor alpha (TNF-α), interferon-γ (IFN-γ), inducible nitric oxide synthase (INOS)] and M2 markers [CD163, interleukin (IL)-4, IL-10, arginase-1 (Arg-1)] in the survival and death groups after MSC transplantation.

RESULTS

The survival rate in the MSC-treated group was increased compared with the DPBS-treated control group (37.5% vs 10%). MSC treatment protected rats with AHF by reducing apoptotic hepatocytes and promoting hepatocyte regeneration. Immunohistochemical analysis showed that MSC treatment significantly increased the expression of EpCAM compared with the control groups (P < 0.001). Expression of EpCAM in the survival group was significantly up-regulated compared with the death group after MSC transplantation (P = 0.003). Transplantation of MSCs significantly improved the expression of CD163 and increased the gene expression of IL-10 and Arg-1 in the survival group. IL-4 concentrations were significantly increased compared to the death group after MSC transplantation (88.51 ± 24.51 pg/mL vs 34.61 ± 6.6 pg/mL, P < 0.001). In contrast, macrophages showed strong expression of CD68, TNF-α, and INOS in the death group. The concentration of IFN-γ was significantly increased compared to the survival group after MSC transplantation (542.11 ± 51.59 pg/mL vs 104.07 ± 42.80 pg/mL, P < 0.001).

CONCLUSION

M2 polarization contributes to the therapeutic effects of MSCs in AHF by altering levels of anti-inflammatory and pro-inflammatory factors.

MyD88-dependent inflammasome activation and autophagy inhibition contributes to Ehrlichia-induced liver injury and toxic shock

Severe hepatic inflammation is a common cause of acute liver injury following systemic infection with Ehrlichia, obligate Gram-negative intracellular bacteria that lack lipopolysaccharide (LPS). We have previously shown that type I IFN (IFN-I) and inflammasome activation are key host-pathogenic mediators that promote excessive inflammation and liver damage following fatal Ehrlichia infection. However, the underlying signals and mechanisms that regulate protective immunity and immunopathology during Ehrlichia infection are not well understood. To address this issue, we compared susceptibility to lethal Ixodes ovatus Ehrlichia (IOE) infection between wild type (WT) and MyD88-deficient (MyD88^-/-) mice. We show here that MyD88^-/- mice exhibited decreased inflammasome activation, attenuated liver injury, and were more resistant to lethal infection than WT mice, despite suppressed protective immunity and increased bacterial burden in the liver. MyD88-dependent inflammasome activation was also dependent on activation of the metabolic checkpoint kinase mammalian target of rapamycin complex 1 (mTORC1), inhibition of autophagic flux, and defective mitophagy in macrophages. Blocking mTORC1 signaling in infected WT mice and primary macrophages enhanced bacterial replication and attenuated inflammasome activation, suggesting autophagy promotes bacterial replication while inhibiting inflammasome activation. Finally, our data suggest TLR9 and IFN-I are upstream signaling mechanisms triggering MyD88-mediated mTORC1 and inflammasome activation in macrophages following Ehrlichia infection. This study reveals that Ehrlichia-induced liver injury and toxic shock are mediated by MyD88-dependent inflammasome activation and autophagy inhibition.

Human monocytic ehrlichiosis (HME) is the most prevalent emerging infectious disease in the United States. Ehrlichia chaffeensis, etiologic agent of HME, is a Gram negative obligate intracellular bacterium transmitted by infected tick bites and can infect different cell type. Although Ehrlichia lack lipopolysaccharide (LPS), they induce potentially life threatening HME that mimic sepsis or toxic shock associated with multi-organ failure. The clinical diagnosis of HME is difficult, and definitive diagnosis is most often retrospective. Late antibiotic treatment is frequently ineffective in preventing disease progression to fatal multi-organ failure. Liver failure is one of the most serious complications and the most frequent cause of death in patients with HME, however we only have a limited understanding of how this liver failure is caused during fatal Ehrlichia infection. The objective of this study is to determine how LPS-negative Ehrlichia activates inflammatory responses in macrophages during Ehrlichia infection to promote liver damage. We show here that MyD88-signaling causes detrimental derangement of the immune system and subsequent liver damage by regulating two key innate immune events in macrophages: autophagy and inflammasome activation. Targeting host-pathogenic pathways in ehrlichiosis can be incorporated into future design of novel therapeutic approaches for HME.

Differential impact of the dual CCR2/CCR5 inhibitor cenicriviroc on migration of monocyte and lymphocyte subsets in acute liver injury

A hallmark of acute hepatic injury is the recruitment of neutrophils, monocytes and lymphocytes, including natural killer (NK) or T cells, towards areas of inflammation. The recruitment of leukocytes from their reservoirs bone marrow or spleen into the liver is directed by chemokines such as CCL2 (for monocytes) and CCL5 (for lymphocytes). We herein elucidated the impact of chemokine receptor inhibition by the dual CCR2 and CCR5 inhibitor cenicriviroc (CVC) on the composition of myeloid and lymphoid immune cell populations in acute liver injury. CVC treatment effectively inhibited the migration of bone marrow monocytes and splenic lymphocytes (NK, CD4 T-cells) towards CCL2 or CCL5 in vitro. When liver injury was induced by an intraperitoneal injection of carbon tetrachloride (CCl₄) in mice, followed by repetitive oral application of CVC, flow cytometric and unbiased t-SNE analysis of intrahepatic leukocytes demonstrated that dual CCR2/CCR5 inhibition in vivo significantly decreased numbers of monocyte derived macrophages in acutely injured livers. CVC also reduced numbers of Kupffer cells (KC) or monocyte derived macrophages with a KC-like phenotype, respectively, after injury. In contrast to the inhibitory effects in vitro, CVC had no impact on the composition of hepatic lymphoid cell populations in vivo. Effective inhibition of monocyte recruitment was associated with reduced inflammatory macrophage markers and moderately ameliorated hepatic necroses at 36h after CCl₄. In conclusion, dual CCR2/CCR5 inhibition primarily translates into reduced monocyte recruitment in acute liver injury in vivo, suggesting that this strategy will be effective in reducing inflammatory macrophages in conditions of liver disease.

Deleterious impact of C3d-binding donor-specific anti-HLA antibodies after pediatric liver transplantation

BACKGROUND

The prevalence and clinical impact of anti-HLA donor-specific antibodies (DSA) after liver transplantation (LT) have not been extensively studied, especially in pediatric population.

METHODS

The present cross-sectional study included 100 patients who underwent a first LT in childhood. Anti HLA immunization study was performed at a single time point during routine follow-up using Luminex® single antigen tests with classical anti-IgG conjugate and anti-C3d conjugate.

RESULTS

The main indication for LT was biliary atresia (52%) and median age at LT was 4.6years. The median time between LT and DSA assessment was 7.8years (range 1-21years). DSA was identified in twenty-four patients (24%) after LT, with a prevalence of 8%, 28%, 33%, 50%, respectively 0-5years, 5-10years, 10-15years and >15years after LT. DSA were mainly class II (23/24) with a mean MFI of 9.731±5.489 and 18 (79.3%) were C3d-binding DSA. Multivariate analysis disclosed that time elapsed since LT (p<0.01) and history of fulminant hepatitis (p=0.04) were significantly associated with a higher rate of DSA. Liver function tests (at time of DSA assessment) were not different according to the presence or not of DSA (or C3d-binding DSA). Regarding histology, the DSA group had a higher rate of chronic rejection, cirrhosis and centrilobular fibrosis or cirrhosis. In addition, patients with C3d-binding DSA and high MFI (>10,000) had a significant poorer long-term graft survival (p=0.03).

CONCLUSION

In our pediatric cohort of LT, prevalence of DSA was high and increased regularly with time. Presence of C3d positive-DSA with high MFI was associated with a higher rate of graft loss.

Galectin-9: Diverse roles in hepatic immune homeostasis and inflammation

Glycan-binding proteins, which include galectins, are involved at all stages of immunity and inflammation, from initiation through resolution. Galectin-9 (Gal-9) is highly expressed in the liver and has a wide variety of biological functions in innate and adaptive immunity that are instrumental in the maintenance of hepatic homeostasis. In the setting of viral hepatitis, increased expression of Gal-9 drives the expansion of regulatory T cells and contraction of effector T cells, thereby favoring viral persistence. The dichotomous nature of Gal-9 is evident in hepatocellular carcinoma, where loss of expression in hepatocytes promotes tumor growth and metastasis, whereas overexpression by Kupffer cells and endothelial cells inhibits the antitumor immune response. In nonalcoholic fatty liver disease, Gal-9 is involved indirectly in the expansion of protective natural killer T-cell populations. In ischemic liver injury, hepatocyte-derived Gal-9 is both diagnostic and cytoprotective. In drug-induced acute liver failure, plasma levels correlate with outcome. Here, we offer a synthesis of recent and emerging findings on Gal-9 in the regulation of hepatic inflammation. Ongoing studies are warranted to better elucidate the pathophysiology of hepatic immune-mediated diseases and to develop new therapeutic interventions using glycan-binding proteins. (Hepatology 2017;66:271-279).

Role of the inflammasome in acetaminophen-induced liver injury and acute liver failure

Drug-induced acute liver failure carries a high morbidity and mortality rate. Acetaminophen overdose is the number one cause of acute liver failure and remains a major problem in Western medicine. Administration of N-acetyl cysteine is an effective antidote when given before the initial rise in toxicity; however, many patients present to the hospital after this stage occurs. As such, treatments which can alleviate late-stage acetaminophen-induced acute liver failure are imperative. While the initial mechanisms of toxicity are well described, a debate has recently occurred in the literature over whether there is a second phase of injury, mediated by inflammatory processes. Critical to this potential inflammatory process is the activation of caspase-1 and interleukin-1β by a molecular complex known as the inflammasome. Several different stimuli for the formation of multiple different inflammasome complexes have been identified. Formation of the NACHT, leucine-rich repeat (LRR) and pyrin (PYD) domains-containing protein 3 (Nalp3) inflammasome in particular, has directly been attributed to late-stage acetaminophen toxicity. In this review, we will discuss the mechanisms of acetaminophen-induced liver injury in mice and man with a particular focus on the role of inflammation and the inflammasome.

Interleukin-23 mediates the pathogenesis of LPS/GalN-induced liver injury in mice

BACKGROUND

Interleukin-23 (IL-23) is required for T helper 17 (Th17) cell responses and IL-17 production in hepatitis B virus infection. A previous study showed that the IL-23/IL-17 axis aggravates immune injury in patients with chronic hepatitis B virus infection. However, the role of IL-23 in acute liver injury remains unclear.

OBJECTIVE

The purpose of this study was to determine the role of the inflammatory cytokine IL-23 in lipopolysaccharide/d-galactosamine (LPS/GalN)-induced acute liver injury in mice.

METHODS

Serum IL-23 from patients with chronic hepatitis B virus (CHB), acute-on-chronic liver failure (ACLF) and healthy individuals who served as healthy controls (HCs) was measured by ELISA. An IL-23p19 neutralizing antibody or an IL-23p40 neutralizing antibody was administered intravenously at the time of challenge with LPS (10μg/kg) and GalN (400mg/kg) in C57BL/6 mice. Hepatic pathology and the expression of Th17-related cytokines, including IL-17 and TNF-α; neutrophil chemoattractants, including Cxcl1, Cxcl2, Cxcl9, and Cxcl10; and the stabilization factor Csf3 were assessed in liver tissue.

RESULTS

Serum IL-23 was significantly upregulated in ACLF patients compared with CHB patients and HCs (P<0.05 for both). Serum IL-23 was significantly upregulated in the non-survival group compared with the survival group of ACLF patients, which was consistent with LPS/GalN-induced acute hepatic injury in mice (P<0.05 for both). Moreover, after treatment, serum IL-23 was downregulated in the survival group of ACLF patients (P<0.001). Compared with LPS/GalN mice, mice treated with either an IL-23p19 neutralizing antibody or an IL-23p40 neutralizing antibody showed less severe liver tissue histopathology and significant reductions in the expression of Th17-related inflammatory cytokine, including IL-17 and TNF-α; neutrophil chemoattractants, including Cxcl1, Cxcl2, Cxcl9, and Cxcl10; and stabilization factors Csf3 within the liver tissue compared with LPS/GalN mice (P<0.05 for all).

CONCLUSION

High serum IL-23 was associated with mortality in ACLF patients and LPS/GalN-induced acute liver injury in mice. IL-23 neutralizing antibodies attenuated liver injury by reducing the expression of Th17-related inflammatory cytokines, neutrophil chemoattractants and stabilization factors within the liver tissue, which indicated that IL-23 likely functions upstream of Th17-related cytokine and chemokine expression to recruit inflammatory cells into the liver.

Molecular cloning of the rabbit interleukin 6 promoter: Functional characterization of rabbit hemorrhagic disease virus response elements in RK-13 cells

Infection with rabbit hemorrhagic disease virus (RHDV) can cause acute liver failure (ALF), leading to severe mortality in rabbits. Inflammatory response, especially the expression of inflammatory cytokines such as interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and IL-6, may play major roles in mediating and amplifying the ALF. Among these cytokines, IL-6 is a multifunctional cytokine with a central role in various physiological inflammatory and immunological processes. In this study, we found that RHDV infection significantly upregulated IL-6 gene expression in vivo. Next, the rabbit IL-6 promoter was cloned and analyzed. Transfection of full-length RHDV cDNA in RK-13 cells upregulated the activity of the IL-6 promoter. A series of 5' deletion constructs demonstrated that AP-1 (activator protein 1), NF-IL6 (nuclear factor interleukin-6), and NF-κB (nuclear factor kappa B) elements were critical for RHDV-induced IL-6 transcription. Besides, the CREB (cAMP-response element binding protein) element may also play an accessory effect on RHDV-induced IL-6 transcription. Collectively, the results elucidate the mechanism of IL-6 induction, and enrich the RHDV pathogenesis in rabbit.

Intestinal Dendritic Cells Are Altered in Number, Maturity and Chemotactic Ability in Fulminant Hepatic Failure

Fulminant hepatic failure (FHF) is defined as rapid acute liver injury, often complicated with spontaneous bacterial peritonitis (SBP). The precise onset of FHF with SBP is still unknown, but it is thought that SBP closely correlates with a weakened intestinal barrier. Dendritic cells (DCs) play a crucial role in forming the intestinal immune barrier, therefore the number, maturity and chemotactic ability of intestinal DCs were studied in FHF. Mouse intestinal and spleen DCs were isolated by magnetic-activated cell sorting (MACS) and surface markers of DCs, namely CD11c, CD74, CD83 and CD86, were identified using flow cytometry. Immunohistochemistry and Western blotting were performed to detect the distribution and expression of CC-chemokine receptor 7 (CCR7) and CC-chemokine receptor 9 (CCR9), as well as their ligands-CC-chemokine ligand 21 (CCL21) and CC-chemokine ligand 25 (CCL25). Real-time PCR was used to detect CCR7 and CCR9 mRNA, along with their ligands-CCL21 and CCL25 mRNA. Flow cytometry analysis showed that the markers CD74, CD83 and CD86 of CD11c+DCs were lower in the D-galactosamine (D-GalN) group and were significantly decreased in the FHF group, while there were no significant changes in the expression of these markers in the lipopolysaccharide (LPS) group. Immunohistochemistry results showed that staining for CCR7 and CCR9, as well as their ligands CCL21 and CCL25, was significantly weaker in the D-GalN and FHF groups compared with the normal saline (NS) group or the LPS group; the FHF group even showed completely unstained parts. Protein expression of CCR7 and CCR9, as well as their ligands- CCL21 and CCL25, was also lower in the D-GalN group and decreased even more significantly in the FHF group. At the gene level, CCR7 and CCR9, along with CCL21 and CCL25 mRNA expression, was lower in the D-GalN group and significantly decreased in the FHF group compared to the NS and LPS groups, consisting with the protein expression. Our study indicated that intestinal DCs were decreased in number, maturity and chemotactic ability in FHF and might contribute to a decreased function of the intestinal immune barrier in FHF.

Role of inflammation and infection in the pathogenesis of human acute liver failure: Clinical implications for monitoring and therapy

Acute liver failure is a rare and devastating clinical condition. At present, emergency liver transplantation is the only life-saving therapy in advanced cases, yet the feasibility of transplantation is affected by the presence of systemic inflammation, infection and resultant multi-organ failure. The importance of immune dysregulation and acquisition of infection in the pathogenesis of acute liver failure and its associated complications is now recognised. In this review we discuss current thinking regarding the role of infection and inflammation in the pathogenesis of and outcome in human acute liver failure, the implications for the management of such patients and suggest directions for future research.

Atg7 Knockdown Augments Concanavalin A-Induced Acute Hepatitis through an ROS-Mediated p38/MAPK Pathway

Concanavalin A (ConA), a T-cell mitogen that induces acute autoimmune hepatitis, is widely used to model pathophysiological processes of human acute autoimmune liver disease. Although autophagy has been extensively studied in the past decade, little is known about its molecular mechanism underlying the regulation of ConA-induced acute hepatitis. In this study, we used a Cre-conditional atg7 KO mouse to investigate the effects of Atg7-associated autophagy on ConA-induced murine hepatitis. Our results demonstrated that atg7 deficiency in mice enhanced macrophage activation and increased pro-inflammatory cytokines upon ConA stimulation. Atg7 silencing resulted in accumulation of dysfunctional mitochondria, disruption of reactive oxygen species (ROS) degradation, and increase in pro-inflammatory cytokines in Raw264.7 cells. p38/MAPK and NF-κB levels were increased upon ConA induction due to Atg7 deficiency. Blocking ROS production inhibited ConA-induced p38/IκB phosphorylation and subsequent intracellular inflammatory responses. Hence, this study demonstrated that atg7 knockout in mice or Atg7 knockdown in cell culture augmented ConA-induced acute hepatitis and related cellular malfunction, indicating protective effects of Atg7 on regulating mitochondrial ROS via a p38/MAPK-mediated pathway. Collectively, our findings reveal that autophagy may attenuate macrophage-mediated inflammatory response to ConA and may be the potential therapeutic targets for acute liver injury.

Intestinal dendritic cells change in number in fulminant hepatic failure

AIM: To investigate the change in intestinal dendritic cell (DC) number in fulminant hepatic failure (FHF).

METHODS: An animal model of FHF was created. Intestinal CD11b/c was detected by immunohistochemistry and Western blot. Quantitative real-time polymerase chain reaction (PCR) was used to detect intestinal integrin-α mRNA expression. Intestinal CD83, CD86, CD74, CD3 and AKT were detected by immunohistochemistry, Western blot and PCR. Phosphorylated-AKT (p-AKT) was detected by immunohistochemistry and Western blot.

RESULTS: In the FHF group [D-galactosamine (D-Galn) + lipopolysaccharide (LPS) group], the mice began to die after 6 h; conversely, in the D-Galn and LPS groups, the activity of mice was poor, but there were no deaths. Immunohistochemistry results showed that in FHF, the expression of CD11b/c (7988400 ± 385941 vs 1102400 ± 132273, P < 0.05), CD83 (13875000 ± 467493 vs 9257600 ± 400364, P < 0.05), CD86 (7988400 ± 385941 vs 1102400 ± 13227, P < 0.05) and CD74 (11056000 ± 431427 vs 4633400 ± 267903, P < 0.05) was significantly increased compared with the normal saline (NS) group. Compared with the NS group, the protein expression of CD11b/c (5.4817 ± 0.77 vs 1.4073 ± 0.37, P < 0.05) and CD86 (4.2673 ± 0.69 vs 1.1379 ± 0.42, P < 0.05) was significantly increased. Itg-α (1.1224 ± 0.3 vs 0.4907 ± 0.19, P < 0.05), CD83 (3.6986 ± 0.40 vs 1.0762 ± 0.22, P < 0.05) and CD86 (1.5801 ± 0.32 vs 0.8846 ± 0.10, P < 0.05) mRNA expression was increased significantly in the FHF group. At the protein level, expression of CD74 in the FHF group (2.3513 ± 0.52) was significantly increased compared with the NS group (1.1298 ± 0.33), whereas in the LPS group (2.3891 ± 0.47), the level of CD74 was the highest (P < 0.05). At the gene level, the relative expression of CD74 mRNA in the FHF group (1.5383 ± 0.26) was also significantly increased in comparison to the NS group (0.7648 ± 0.22; P < 0.05). CD3 expression was the highest in the FHF group (P < 0.05). In the FHF, LPS and D-Galn groups, the expression of AKT at the protein and mRNA levels was elevated compared with the NS group, but there was no statistical significance (P > 0.05). The p-AKT protein expression in the FHF (1.54 ± 0.06), LPS (1.56 ± 0.05) and D-Galn (1.29 ± 0.03) groups was higher than that in the NS group (1.07 ± 0.03) (P < 0.05).

CONCLUSION: In FHF, a large number of DCs mature, express CD86, and activate MHC class II molecular pathways to induce a T cell response, and the AKT pathway is activated.

NOTCH reprograms mitochondrial metabolism for proinflammatory macrophage activation

Metabolic reprogramming is implicated in macrophage activation, but the underlying mechanisms are poorly understood. Here, we demonstrate that the NOTCH1 pathway dictates activation of M1 phenotypes in isolated mouse hepatic macrophages (HMacs) and in a murine macrophage cell line by coupling transcriptional upregulation of M1 genes with metabolic upregulation of mitochondrial oxidative phosphorylation and ROS (mtROS) to augment induction of M1 genes. Enhanced mitochondrial glucose oxidation was achieved by increased recruitment of the NOTCH1 intracellular domain (NICD1) to nuclear and mitochondrial genes that encode respiratory chain components and by NOTCH-dependent induction of pyruvate dehydrogenase phosphatase 1 (Pdp1) expression, pyruvate dehydrogenase activity, and glucose flux to the TCA cycle. As such, inhibition of the NOTCH pathway or Pdp1 knockdown abrogated glucose oxidation, mtROS, and M1 gene expression. Conditional NOTCH1 deficiency in the myeloid lineage attenuated HMac M1 activation and inflammation in a murine model of alcoholic steatohepatitis and markedly reduced lethality following endotoxin-mediated fulminant hepatitis in mice. In vivo monocyte tracking further demonstrated the requirement of NOTCH1 for the migration of blood monocytes into the liver and subsequent M1 differentiation. Together, these results reveal that NOTCH1 promotes reprogramming of mitochondrial metabolism for M1 macrophage activation.

Pretreatment of lipopolysaccharide (LPS) ameliorates D-GalN/LPS induced acute liver failure through TLR4 signaling pathway

Endotoxin tolerance (ET) is an important phenomenon, which affects inflammation and phagocytosis. Pretreatment with low dose of lipopolysaccharide (LPS) can protect liver injury from various hepatotoxicants such as acetaminophen and pseudomonas aeruginosa exotoxin A. The current study aimed to investigate the protecting mechanisms of endotoxin tolerance in acute liver failure induced by D-galactosamine (D-GalN)/LPS and possible role of toll-like receptors 4 (TLR4) signaling pathway in this phenomenon. Acute liver failure was induced by Injection of D-GalN/LPS. To mimic endotoxin tolerance, male Sprague-Dawley rats were treated with low dose of LPS (0.1 mg/kg once a day intraperitoneally for consecutive five days) before subsequent injection of D-GalN/LPS. Rat survival was determined by survival rate. Liver injury was confirmed by serum biochemical and liver histopathological examination. Inflammatory cytokines were determined by ELISA and nuclear factor-kappa B (NF-κB) (P65), toll-like receptors 4 (TLR4) and Interleukin-1 receptor-associated kinase-1 (IRAK-1) were measured by reverse transcriptase polymerase chain reaction and western blot respectively. Pretreatment of LPS significantly improved rat survival. Moreover, rats pretreated with LPS exhibited lower serum enzyme (ALT, AST and TBiL) level, lower production of inflammatory cytokines and more minor liver histopathological damage than rats without pretreatment of LPS. LPS pretreatment suppressed production of TLR4 and IRAK-1. LPS pretreatment also inhibited activation of hepatic NF-κB. These results indicated that endotoxin tolerance contributed to liver protection against D-GalN/LPS induced acute liver failure through down-regulation of TLR4 and NF-κB pathway.

Immune dysfunction in cirrhosis

Innate and adaptive immune dysfunction, also referred to as cirrhosis-associated immune dysfunction syndrome, is a major component of cirrhosis, and plays a pivotal role in the pathogenesis of both the acute and chronic worsening of liver function. During the evolution of the disease, acute decompensation events associated with organ failure(s), so-called acute-on chronic liver failure, and chronic decompensation with progression of liver fibrosis and also development of disease specific complications, comprise distinct clinical entities with different immunopathology mechanisms. Enhanced bacterial translocation associated with systemic endotoxemia and increased occurrence of systemic bacterial infections have substantial impacts on both clinical situations. Acute and chronic exposure to bacteria and/or their products, however, can result in variable clinical consequences. The immune status of patients is not constant during the illness; consequently, alterations of the balance between pro- and anti-inflammatory processes result in very different dynamic courses. In this review we give a detailed overview of acquired immune dysfunction and its consequences for cirrhosis. We demonstrate the substantial influence of inherited innate immune dysfunction on acute and chronic inflammatory processes in cirrhosis caused by the pre-existing acquired immune dysfunction with limited compensatory mechanisms. Moreover, we highlight the current facts and future perspectives of how the assessment of immune dysfunction can assist clinicians in everyday practical decision-making when establishing treatment and care strategies for the patients with end-stage liver disease. Early and efficient recognition of inappropriate performance of the immune system is essential for overcoming complications, delaying progression and reducing mortality.

NLRP3 inflammasome activation in D-galactosamine and lipopolysaccharide-induced acute liver failure: role of heme oxygenase-1

D-Galactosamine (GalN) and lipopolysaccharide (LPS) are commonly used to study mechanisms of hepatic malfunction that result in hepatic inflammation and subsequent fulminant hepatic failure. Inflammasomes are intracellular multiprotein complexes that in response to cellular danger signals trigger the biological maturation of proinflammatory cytokines. Heme oxygenase-1 (HO-1) is a cytoprotective enzyme that induces anti-inflammatory and antioxidant activity against oxidative cellular stress. This study examined activation of the NACHT, LRR, and PYD domain-containing protein 3 (NLRP3) inflammasome in GalN/LPS-induced hepatic injury and the role of HO-1 in the signaling pathways of inflammasome. Mice (C57BL/6) were pretreated twice with hemin (HO-1 inducer, 30 mg/kg) and zinc protoporphyrin (ZnPP; HO-1 inhibitor, 10mg/kg) at 12 and 2h before GalN (800 mg/kg)/LPS (40 μg/kg) administration. HO-1 induction with hemin reversed the lethality induced by GalN/LPS administration, and ZnPP pretreatment blocked this change. Lipid peroxidation markedly increased after GalN/LPS treatment, whereas glutathione content decreased in the GalN/LPS group. These changes were attenuated by hemin, but ZnPP reversed the effects of hemin. Serum levels of tumor necrosis factor-α (TNF-α) and interleukin (IL)-1β increased after GalN/LPS treatment; these increases were attenuated by hemin. Hepatic mRNA levels of TNF-α, IL-1β, and NLRP3 increased after GalN/LPS treatment, and hemin attenuated increases in TNF-α and IL-1β. After GalN/LPS treatment, the hepatic expression of NLRP3, ASC, and caspase-1 (p10) was increased. In immunoprecipitation studies, hemin attenuated the interaction of NLRP3 with ASC and caspase-1. GalN/LPS induced expression of the thioredoxin-interacting protein (TXNIP) gene and the interaction between NLRP3 and TXNIP; again, hemin attenuated these effects. The effects of hemin were reversed by ZnPP. Our findings suggest that activation of the NLRP3 inflammasome leads to a GalN/LPS-induced inflammatory response through TXNIP-NLRP3 interaction. Furthermore, HO-1 overexpression may protect the liver against GalN/LPS-induced inflammation through suppression of the NLRP3 signaling pathway.

Mechanisms of liver involvement in systemic disease

The liver may be injured during the course of many systemic diseases. The mechanisms of injury can be broadly divided into four pathways: vascular, toxic, immune, and hormonal. Vascular obstruction may be an early event but is also the late common pathway from all mechanisms. Despite the large number of possible initiating factors, the end results are few, including death of hepatocytes or cholangiocytes, leading to the stereotyped syndromes of acute liver failure, non-cirrhotic portal hypertension, or cirrhosis. This small number of outcomes is a reflection of the few anatomic patterns that can be generated by microvascular obstruction. Vascular obstruction may occur by thrombosis, inflammation, or congestive injury. The innate immunity pathway is activated by endotoxin and other agents, leading to inflammatory infiltration, release of cytokines and reactive oxygen species, and necrosis. The adaptive immune pathway involves the generation of antibodies and antigen-specific cell-mediated attack on hepatic cells. Hormonal effects are principally involved when overnutrition leads to hyperinsulinemia followed by hepatocellular necrosis.

Restoring the Treg cell to Th17 cell ratio may alleviate HBV-related acute-on-chronic liver failure

AIM: To investigate the role of T helper 17 cells (Th17) and regulatory T cells (Treg) in hepatitis B virus (HBV)-related acute-on-chronic liver failure (ACLF).

METHODS: We enrolled 79 patients with HBV infection into the study, 50 patients with HBV-related ACLF and 29 patients with chronic hepatitis B (CHB), from the First Affiliated Hospital of Medical College from January 2009 to June 2012. The ACLF patients were diagnosed according to the criteria recommended by The 19^th Conference of the Asian Pacific Association for the Study of the Liver in 2009. Twenty healthy individuals with a similar gender and age structures to the two patient groups were also included as the normal controls (NC). Of the 50 ACLF patients, 28 were subsequently classified as non-survivors: 19 patients died from multi-organ failure, 3 underwent liver transplantation, and 6 discontinued therapy during follow-up because of financial reasons. The remaining 22 ACLF patients whose liver and anticoagulation function recovered to nearly normal levels within the next 6 mo were classified as survivors. The number of circulating Treg and Th17 cells was determined upon diagnosis and during the 8th week of follow-up through flow cytometry.

RESULTS: The percentage of circulating Treg cells in the ACLF group was significantly higher than that in the CHB group (5.50% ± 1.15% vs 3.30% ± 1.13%, P < 0.01). The percentages of circulating Th17 cells in the ACLF and the CHB groups were significantly higher than that in the NC group (6.32% ± 2.22% vs 1.56% ± 0.44%, P < 0.01; 3.53% ± 1.65% vs 1.56% ± 0.44%, P < 0.01). No significant difference in Treg cell to Th17 cell ratio was observed between the ACLF group and the CHB group (0.98 ± 0.44 vs 1.12 ± 0.64, P = 0.991), whereas those in the two HBV infection groups were significantly lower than that in the NC group (1.85 ± 1.22; both P < 0.01). The percentage of Treg cells in the survivors during the 8^th week of follow-up was significantly lower than that during peak ACLF severity [total bilirubin (TBIL) peak] (3.45% ± 0.97% vs 5.18% ± 1.02%, P < 0.01). The percentage of Th17 cells in survivors during the 8^th week of follow-up was significantly lower than that during the peak TBIL (2.89% ± 0.60% vs 5.24% ± 1.46%; P < 0.01). The Treg cell to Th17 cell ratio during the 8^th week of follow-up was significantly higher than that during the TBIL peak (1.22 ± 0.36 vs 1.10 ± 0.54; P < 0.05).

CONCLUSION: Restoring the Treg cell to Th17 cell ratio during the follow-up phase of ACLF could maintain the immune system at a steady state, which favours good prognosis.

Granulocyte-colony stimulating factor therapy improves survival in patients with hepatitis B virus-associated acute-on-chronic liver failure

AIM: To evaluate the safety and efficacy of granulocyte-colony stimulating factor (G-CSF) therapy in patients with hepatitis B virus (HBV)-associated acute-on-chronic liver failure (ACLF).

METHODS: Fifty-five patients with HBV-associated ACLF were randomized into two groups: the treatment group and the control group. Twenty-seven patients in the treatment group received G-CSF (5 μg/kg per day, six doses) treatment plus standard therapy, and 28 patients in the control group received standard therapy only. The peripheral CD34⁺ cell count was measured consecutively by flow cytometry. Circulating white blood cell count, biochemical parameters, and other clinical data of these patients were recorded and analyzed. All patients were followed up for a period of 3 mo to evaluate the changes in liver function and survival rate.

RESULTS: The peripheral neutrophil and CD34⁺ cell counts in the G-CSF group increased on day 3 from the onset of therapy, continued to rise on day 7, and remained elevated on day 15 compared to those of the control group. Child-Turcotte-Pugh score of patients in the treatment group was improved on day 30 from the onset of G-CSF therapy, compared to that in the controls (P = 0.041). Model for End-Stage of Liver Disease score of patients in the treatment group was improved on day 7 (P = 0.004) and remained high on day 30 from the onset of G-CSF therapy (P < 0.001) compared to that in controls. After 3 mo of follow-up observation, the survival rate in the treatment group (48.1%) was significantly higher than that in the control group (21.4%) (P = 0.0181).

CONCLUSION: G-CSF therapy promoted CD34⁺ cell mobilization in patients with HBV-associated ACLF, and improved the liver function and the survival rate of these patients.

The evolving story of macrophages in acute liver failure

Acute liver failure (ALF) remains a worldwide problem. The innate immune system acts as an important regulator of ALF. Kupffer cells (KCs), the resident macrophages in liver, play a key role in liver innate immune response. Recent researches have shown that macrophages display a remarkable plasticity and can differentiate into functionally diverse subsets. However, the dynamic polarized phenotypes and functional status of macrophages at different stage of ALF are not clear. In this paper, we present a review of evidence that KCs play a significant role in the pathogenesis of ALF, including the phenotype and functions of macrophages, signaling pathways involved in macrophage functional status and cell-crosstalks of KCs with other immune cells. More information on macrophages will promote a better understanding of the cellular molecular mechanisms of ALF and provide new insights for the development of therapeutic targets for ALF.

The ROS scavenger, NAC, regulates hepatic Vα14iNKT cells signaling during Fas mAb-dependent fulminant liver failure

Uncontrolled systemic activation of the immune system is an early initiating event that leads to development of acute fulminant liver failure (FLF) in mice after treatment with agonistic Fas mAb. In this study, we demonstrate that treatment of mice with N-acetylcysteine (NAC), an ROS scavenger and glutathione (GSH) precursor, almost completely abolished Fas mAb-induced FLF through suppression of Vα14iNKT cell activation, IFN-γ signaling, apoptosis and nitrotyrosine formation in liver. In addition, enrichment of the liver with GSH due to Vα14iNKT cells deficiency, induced an anti-inflammatory response in the liver of Jα18(-/-) mice that inhibited apoptosis, nitrotyrosine formation, IFN-γ signaling and effector functions. In summary, we propose a novel and previously unrecognized pro-inflammatory and pro-apoptotic role for endogenous ROS in stimulating Th1 signaling in Vα14iNKT cells to promote the development of FLF. Therefore, our study provides critical new insights into how NAC, a ROS scavenger, regulates Th1 signaling in intrahepatic Vα14iNKT cells to impact inflammatory and pathological responses.

Liver failure caused by light chain deposition disease associated with multiple myeloma

Acute liver failure is an unusual complication in multiple myeloma. Here, we report a case of multiple myeloma with light chain deposition disease (LCDD) that presented with progressive jaundice due to intrahepatic cholestasis. Diagnosis was made after liver biopsy that showed deposition of kappa light chains occupying perisinusoidal spaces. The patient developed encephalopathy and liver failure and died despite prompt initiation of dexamethasone therapy. The current prognosis of multiple myeloma patients with liver failure due to LCDD is dismal. New therapeutic strategies might improve this condition.

Acute liver failure caused by drug-induced hypersensitivity syndrome associated with hyperferritinemia

Drug-induced hypersensitivity syndrome (DIHS) is a severe reaction usually characterized by fever, rash, and multiorgan failure, occurring 2-6 wk after drug introduction. It is an immune-mediated reaction involving macrophage and T-lymphocyte activation and cytokine release. A 54-year-old woman was diagnosed with rheumatic arthritis and initiated salazosulfapyridine by mouth. About 10 d later, she had a high fever, skin rash and liver dysfunction. She was admitted to hospital and diagnosed with a drug eruption. She was treated with oral prednisolone 30 mg/d; however, she developed high fever again and her blood tests showed acute liver failure and cytopenia associated with hyperferritinemia. She was diagnosed with acute liver failure and hemophagocytosis caused by DIHS. She was transferred to the Department of Medicine and Bioregulatory Science, Kyushu University, where she was treated with arterial steroid injection therapy. Following this treatment, her liver function improved and serum ferritin immediately decreased. We hypothesized that an immune-mediated reaction in DIHS may have generated over-activation of macrophages and T-lymphocytes, followed by a cytokine storm that affected various organs. The measurement of serum ferritin might be a useful marker of the severity of DIHS.

[Promoting effect on NK cells induced by myeloid-derived suppressor cells in acute fulminate hepatitis of mice]

OBJECTIVE

To investigate the interaction between myeloid-derived suppressor cells (MDSCs) and nature killer cells during acute fulminate hepatitis.

METHODS

Acute fulminate hepatitis were induced by i.p. co-injection of LPS and D-GalN in mice, and the ratio of MDSCs,NK cells and the activation of NK cells in different tissues were analyzed by FACS at 0 h,1.5 h,3 h and 6 h.

RESULTS

The percentage of MDSCs and NKG2D+NK cells in different tissues increased as acute fulminate hepatitis progressed, with the increased NK cells in liver tissue. The mean fluorescence intensity of NKG2D on NK cells in different tissues were also enhanced.

CONCLUSION

MDSCs induce the proliferation and activation of NK cells in mice with acute fulminate hepatitis.

[Research of PD-1 expression in CD8+ T cell of peripheral blood with HBV-associated acute-on-chronic liver failure]

OBJECTIVE

To analyze PD-1 expression in CD8 + T cell of Peripheral blood with HBV-associated acute-on-chronic liver failure and effect on CD8+ T cell.

METHODS

We selected 60 patients with HBV-ACLF and collected their peripheral blood. We analyzed the expressions of PD-1, CD95, perforin, granzyme A, granzyme B, CD107a on CD8+ T lymphocytes and the expression of PD-L1 on monocytes peripheral blood by using flow cytometry. 15 liver cirrhosis patients( LC) and 15 healthy individuals( HC) are control groups.

RESULT

PD-1 expression was (1) The PD-1 expression in HBV-ACLF patients was significantly elevated compared with those in HC and lower in improved group than that in invalid group and death group (P < 0.05) and increased from prophase, metaphase to advanced stage (P < 0.05). Moreover, (2) PD-L1 expression on monocytes was positively correlated with disease progression. (P < 0.05). (3) Both PD-1 and CD95 expressions were higher in dead group than those in improved and non-improved groups. Perforin, granzymes and CD107a expressions on CD8+ T cells significantly increased in dead group compared with those in improved and non-improved groups (P < 0.05). However, PD-1 expressions on these cells were lower, compared with normal persons.

CONCLUSIONS

The expression of PD-1 and PD-L1 in HBV-ACLF patients was positively correlated with disease progression. The elevated PD-1 expression promoted apoptosis of CD8+ T cells. For HBV-ACLF patients, the PD-1 expression on effector CD8+ T cells was lower than those in other CD8+ T cells, which maybe accounted for the failure to controlling immune injury in liver.

Innate host-defensive function of a hepatic lipid fraction produced in low-dose carbon tetrachloride-pretreated mice

We investigated the tolerance of mice to carbon tetrachloride (CCl(4))-induced fulminant hepatic failure (FHF) in mice with daily intraperitoneal (i.p.) injection of high-dose CCl(4) (4 ml/kg). The tolerance was induced by preliminary i.p. administration of a low dose of CCl(4) (1 ml/kg) 24 h prior to the initial high-dose administration of CCl(4) (4 ml/kg). These mice were protected from death because of FHF induced by subsequent daily high-dose injection of CCl(4). This protection appears to result from a priming effect of the innate immune activity of CCl(4). The crude lipid extracted from the liver of low-dose CCl(4) injected mice also protected mice from death because of FHF. Examination of the innate immunological system using OK-432 (picibanil) revealed that the protection results from a priming effect of the innate immune activity with the low-dose CCl(4) or the crude lipid extract.

[The functions of liver natural killer cells in murine fulminant hepatitis induced by murine hepatitis virus strain 3]

OBJECTIVES

To investigate the role of liver natural killer cells (NK cells) in murine hepatitis virus strain 3 (MHV-3) induced murine fulminant hepatitis.

METHOD

Balb/cJ mice (6-8 weeks, female) were intraperitoneally injected with 100 PFU MHV-3. The numbers of NK cells in their livers, spleens, blood and bone marrow and the expression of CD69 on liver NK cells at 0, 24, 48 and 70 h after MHV-3 infection were analyzed by flow cytometry. The cytotoxic activity of liver NK cells was detected by a non-radioactive cytotoxicity assay. The levels of IFN gamma produced by hepatic NK cells were detected by intracellular cytokine staining.

RESULT

Following MHV-3 infection, the proportion of liver NK cells in the mice increased remarkably and reached the peak (43.9%+/-2.3%) at 48 h, then kept a high proportion until the mice were sacrificed. The proportion of NK cells in the peripheral blood also significantly increased and reached the peak (18.0%+/-5.4%) at 48 h. However, there were few NK cells in the peripheral blood at 70 h after infection; the ratio was only 1.3%+/-0.6%. In the spleens and bone marrow, the proportions of NK cells were both significantly decreased from 0 h to 48 h and then slightly increased. The expression of CD69 on liver NK cells was highly up-regulated after the infection and the cytotoxic activity of hepatic NK cells at 48 h was also significantly enhanced. In addition, an increase in IFN gamma production by hepatic NK cells was observed at 48 h.

CONCLUSION

After MHV-3 infection, NK cells were recruited to the liver quickly, probably from the spleen and bone marrow. Recruited NK cells remarkably express CD69, enhance cytotoxic activity and IFN gamma production, which correlate with the disease severity of fulminant viral hepatitis. Our results suggest that liver NK cells may play a pivotal role in the pathogenesis of fulminant viral hepatitis.

Vascular endothelial growth factor reduces Fas-mediated acute liver injury in mice

BACKGROUND AND AIM

Fulminant hepatitis is still a fatal liver disease, and no specific treatment for it has been available. Vascular endothelial growth factor (VEGF) is the focus of attention because of its various actions. We investigated the effect of vascular endothelial growth factor (VEGF) on Fas-induced fulminant hepatic failure (FHF).

METHOD

Male Balb/c mice were treated with an intraperitoneal injection of an anti-Fas antibody (Jo-2 Ab) with or without premedication with intraperitoneally administered human recombinant VEGF.

RESULTS

The serum level of alanine aminotransferase (ALT) was up to 300 times higher that of normal mice following the Jo-2 Ab injection, and histological analysis revealed hepatic injury and massive hepatocyte apoptosis. The VEGF significantly suppressed an elevation in serum ALT levels and hepatocyte apoptosis. Immunohistochemically, VEGF-treated mice showed that Bcl-xL in hepatocytes was strongly expressed.

CONCLUSIONS

Since hepatocytes do not express VEGF receptors, we speculated that VEGF acts on sinusoidal endothelial cells (SECs) and promotes production of cytokines such as hepatocyte growth factor in SECs, resulting in reducing apoptosis through an increase expression of Bcl-xL in hepatocytes. We suggest that VEGF has a potent antiapoptotic effect on hepatocytes through cell-cell interaction between SECs and hepatocytes.

Brain cytokine flux in acute liver failure and its relationship with intracranial hypertension

BACKGROUND

In acute liver failure (ALF), it is unclear whether the systemic inflammatory response associated with intracranial hypertension is related to brain cytokine production.

AIM

To determine the relationship of brain cytokine production with severity of intracranial hypertension in ALF patients.

METHOD

We studied 16 patients with ALF. All patients were mechanically ventilated and cerebral blood flow measured using the Kety-Schmidt technique and intracranial pressure (ICP) measured with a Camino subdural catheter. We sampled blood from an artery and a reverse jugular catheter to measure proinflammatory cytokines (TNF-alpha, IL-6 and IL-1beta) and ammonia. Additionally, in 3 patients, serial samples were obtained over a 72 h period.

RESULTS

In ALF patients a good correlation between arterial pro-inflammatory cytokines and ICP (r (2) = 0.34, 0.50 and 0.52; for IL-6, IL-1beta and TNF-alpha respectively) was observed. There was a positive cerebral cytokine 'flux' (production), in ALF patients with uncontrolled ICP. Plasma ammonia between groups was not statistically significant. In the ALF patients studied longitudinally, brain proinflammatory cytokine production was associated with uncontrolled ICP.

CONCLUSION

Our results provide novel data supporting brain production of cytokines in patients with uncontrolled intracranial hypertension indicating activation of the inflammatory cascade in the brain. Also, the appearance of these cytokines in the jugular bulb catheter may indicate a compromised blood brain barrier at this late stage.

Methylprednisolone injection via the portal vein suppresses inflammation in acute liver failure induced in rats by lipopolysaccharide and d-galactosamine

BACKGROUND

We have reported that hepatic arterial steroid injection is an effective therapy to rescue patients from fulminant or severe acute hepatic failure. We speculate that a high concentration of steroid suppresses inflammatory processes in the liver directly by restraining activated inflammatory cells, including macrophages. To analyse the detailed mechanism, steroid injection via the portal vein was performed in an experimental model of liver damage.

METHODS

Rats subjected to lipopolysaccharide and d-galactosamine injection were treated with a methylprednisolone injection via the tail vein or the portal vein. The survival rate, serum levels of inflammatory cytokines and apoptotic cell counts in the liver were analysed.

RESULTS

The survival rate was significantly improved by steroid injection, especially via the portal vein. Serum values of alanine aminotransferase, tumor necrosis factor-alpha and interferon-gamma were reduced in the treated groups, especially the group given portal venous injections. Apoptotic cell counts in the liver were significantly lower in the group injected with steroid via the portal vein.

CONCLUSION

In the model rats, high concentrations of steroid in the liver acted on inflammatory cells and suppressed inflammatory cytokines and liver cell death. The mechanism is suggested to be the same for arterial steroid injection therapy in patients with acute hepatic failure.

Soluble CD163 from activated macrophages predicts mortality in acute liver failure

BACKGROUND/AIMS

Soluble CD163 (sCD163) is a scavenger receptor shed in serum during inflammatory activation of macrophages. We investigated if sCD163 was increased and predicted outcome in acute liver failure (ALF).

METHODS

Samples from 100 consecutive patients enrolled in the U.S. ALF Study Group for whom sera were available were collected on days 1 and 3, and clinical data were obtained prospectively. sCD163 levels were determined by ELISA.

RESULTS

The median level of sCD163 was significantly increased in ALF (21.1mg/l (range 3.6-74.9)) as compared to healthy controls (2.3mg/l (0.65-5.6), p<0.0001) and patients with stable liver cirrhosis (9.8mg/l (3.6-16.9), p=0.0002). sCD163 on day 1 correlated significantly with ALT, AST, bilirubin, and creatinine. sCD163 concentrations on day 3 were elevated in patients with fatal outcome of disease compared to spontaneous survivors, 29.0mg/l (7.2-54.0) vs. 14.6mg/l (3.5-67.2), respectively (p=0.0025). Patients that were transplanted had intermediate levels. Sensitivity and specificity at a cut-off level of 26mg/l was 62% and 81%, respectively.

CONCLUSIONS

Activated macrophages are involved in ALF resulting in a 10-fold increase in sCD163. A high level (>26mg/l) of sCD163 was significantly correlated with fatal outcome and might be used with other parameters to determine prognosis.

The significance of autoantibodies and immunoglobulins in acute liver failure: a cohort study

BACKGROUND/AIMS

The cause of cryptogenic ('seronegative') acute liver failure (ALF) is unknown; the presence of non-organ specific autoantibodies (NOSA) may indicate an autoimmune pathogenesis. We investigated the prevalence of autoimmune features including antibodies to soluble liver antigen (anti-SLA) determined by Radioligand assay (RLA) in ALF patients.

METHODS

The prevalence and relationship to the immunoglobulin (Ig) response of NOSA and anti-SLA were determined in 73 ALF patients of different causes. Patients were scored using the revised system for diagnosis of autoimmune hepatitis (AIH).

RESULTS

Autoantibodies were present in 23 (32%) patients; 16 had anti-SLA, 6 ANA, 4 ASM and 1 AMA. They were absent in paracetamol-related disease and present in 23 of 53 (43%) of non-paracetamol (NP) cases (p<0.0003). Two of 16 (13%) with NP drug-induced (NPDI), 9 of 21 (43%) viral and 5 of 16 (31%) cryptogenic cases had anti-SLA. NOSA and anti-SLA were not associated with liver injury severity or outcome. IgM was higher in those with viral disease (p<0.00001). AIH scores classified 50% of cryptogenic cases as 'probable autoimmune hepatitis'.

CONCLUSIONS

Autoantibodies are common in ALF; cryptogenic cases have features suggestive of an autoimmune pathogenesis. IgM is elevated in viral cases but infrequently in ALF of other causes.

Antimitochondrial antibodies in acute liver failure: implications for primary biliary cirrhosis

In our previous work, including analysis of more than 10,000 sera from control patients and patients with a variety of liver diseases, we have demonstrated that with the use of recombinant autoantigens, antimitochondrial autoantibodies (AMAs) are only found in primary biliary cirrhosis (PBC) and that a positive AMA is virtually pathognomonic of either PBC or future development of PBC. Although the mechanisms leading to the generation of AMA are enigmatic, we have postulated that xenobiotic-induced and/or oxidative modification of mitochondrial autoantigens is a critical step leading to loss of tolerance. This thesis suggests that a severe liver oxidant injury would lead to AMA production. We analyzed 217 serum samples from 69 patients with acute liver failure (ALF) collected up to 24 months post-ALF, compared with controls, for titer and reactivity with the E2 subunits of pyruvate dehydrogenase, branched chain 2-oxo-acid dehydrogenase, and 2-oxo-glutarate dehydrogenase. AMAs were detected in 28/69 (40.6%) ALF patients with reactivity found against all of the major mitochondrial autoantigens. In addition, and as further controls, sera were analyzed for autoantibodies to gp210, Sp100, centromere, chromatin, soluble liver antigen, tissue transglutaminase, and deaminated gliadin peptides; the most frequently detected nonmitochondrial autoantibody was against tissue transglutaminase (57.1% of ALF patients).

CONCLUSION

The strikingly high frequency of AMAs in ALF supports the thesis that oxidative stress-induced liver damage may lead to AMA induction. The rapid disappearance of AMAs in these patients provides further support for the contention that PBC pathogenesis requires additional factors, including genetic susceptibility.

Hepatitis E virus infection and fulminant hepatic failure during pregnancy

BACKGROUND AND AIM

Hepatitis E virus (HEV) infection leading to fulminant hepatic failure (FHF) and high mortality is a common feature in Indian women during the second and third trimesters of pregnancy. An altered status of hormones and immunity are observed during pregnancy but the actual cause of high mortality is still unknown. The present study was carried out to analyze CD3, CD4 and CD8 T cell counts and to assay the level of pregnancy-related hormones such as estrogen, progesterone and beta-HCG in order to discover the role played by these factors.

METHODS

One hundred patients (50 pregnant and 50 non-pregnant women) with FHF and 150 pregnant healthy females without liver disease as controls were recruited for the study. Serological tests for all viral markers using ELISA kits and detection of HEV RNA by reverse transcription-polymerase chain reaction (RT-PCR) were carried out in all cases. CD3, CD4 and CD8 T cell counts were analyzed by fluorescence activated cell sorter (FACS) while hormone assay was performed by commercially available RIA kits.

RESULTS

Serologically (38/50; 76%) as well as by RT-PCR (28/50; 56%), a significantly higher HEV positivity rate was found in pregnant FHF patients compared to non-pregnant women (serologically 15/50; 30%; RT-PCR 7/50; 14%). CD4 counts were lower (P < 0.05), while CD8 counts were higher (P < 0.05), and their ratio (CD4/CD8) in HEV positive pregnant FHF patients was significantly lower (P < 0.01) when compared to that of HEV negative pregnant FHF women or controls. Levels of estrogen, progesterone and beta-HCG were also found to be higher (P < 0.001) in HEV positive pregnant FHF patients when compared to HEV negative patients or controls. HEV infected pregnant FHF patients had a significantly higher mortality rate of 65.8% (25/38) compared to 23.5% (4/15) in HEV positive non-pregnant women (P < 0.001).

CONCLUSIONS

Pregnancy appears to be a potential risk factor for viral replication and an extreme low immune status of Indian/Asian pregnant women. It is suggested that diminished cellular immunity (indicated by a decrease in CD4, an increase in CD8 cell counts and lowered CD4/CD8 cell ratio) and a high level of steroid hormones that influence viral replication/expression during pregnancy appear to be the plausible reasons for severity of the disease.