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Background and Aims: The risk of developing HCC in chronically infected patients with AQ2 HCV with liver cirrhosis is significantly elevated. This risk remains high even after a sustained virological response with direct-acting antivirals. To date, disease-associated signatures of NK cells indicating HCC development are unclear., Approach and Results: This study investigated NK cell signatures and functions in 8 cohorts covering the time span of HCC development, diagnosis, and onset. In-depth analysis of NK cell profiles from patients with cirrhosis who developed HCC (HCV-HCC) after sustained virological response compared with those who remained tumor-free (HCV-noHCC) revealed increasingly dissimilar NK cell signatures over time. We identified expression patterns with persistently high frequencies of TIM-3 and CD38 on NK cells that were largely absent in healthy controls and were associated with a high probability of HCC development. Functional assays revealed that the NK cells had potent cytotoxic features. In contrast to HCV-HCC, the signature of HCV-noHCC converged with the signature found in healthy controls over time. Regarding tissue distribution, single-cell sequencing showed high frequencies of these cells in liver tissue and the invasive margin but markedly lower frequencies in tumors., Conclusions: We show that HCV-related HCC development has profound effects on the imprint of NK cells. Persistent co-expression of TIM-3hi and CD38 + on NK cells is an early indicator for HCV-related HCC development. We propose that the profiling of NK cells may be a rapid and valuable tool to assess the risk of HCC development in a timely manner in patients with cirrhosis after HCV cure., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc.)

Background and Aims: Nonalcoholic fatty liver disease, especially nonalcoholic steatohepatitis (NASH), has become a major cause of liver transplantation and liver-associated death. NASH is the hepatic manifestation of metabolic syndrome and is characterized by hepatic steatosis, inflammation, hepatocellular injury, and different degrees of fibrosis. However, there is no US Food and Drug Administration-approved medication to treat this devastating disease. Therapeutic activators of the AMP-activated protein kinase (AMPK) have been proposed as a potential treatment for metabolic diseases such as NASH. Cordycepin, a natural product isolated from the traditional Chinese medicine Cordyceps militaris, has recently emerged as a promising drug candidate for metabolic diseases., Approach and Results: We evaluated the effects of cordycepin on lipid storage in hepatocytes, inflammation, and fibrosis development in mice with NASH. Cordycepin attenuated lipid accumulation, inflammation, and lipotoxicity in hepatocytes subjected to metabolic stress. In addition, cordycepin treatment significantly and dose-dependently decreased the elevated levels of serum aminotransferases in mice with diet-induced NASH. Furthermore, cordycepin treatment significantly reduced hepatic triglyceride accumulation, inflammatory cell infiltration, and hepatic fibrosis in mice. In vitro and in vivo mechanistic studies revealed that a key mechanism linking the protective effects of cordycepin were AMPK phosphorylation-dependent, as indicated by the finding that treatment with the AMPK inhibitor Compound C abrogated cordycepin-induced hepatoprotection in hepatocytes and mice with NASH., Conclusion: Cordycepin exerts significant protective effects against hepatic steatosis, inflammation, liver injury, and fibrosis in mice under metabolic stress through activation of the AMPK signaling pathway. Cordycepin might be an AMPK activator that can be used for the treatment of NASH., (© 2021 The Authors. Hepatology published by Wiley Periodicals LLC on behalf of American Association for the Study of Liver Diseases.)

Background and Aims: PreS mutants of HBV have been reported to be associated with HCC. We conducted a longitudinal study of the role of HBV preS mutations in the development of HCC, particularly in patients with chronic hepatitis B (CHB) having low HBV DNA or alanine aminotransferase (ALT) levels, and investigated the effects of secretion-defective preS2 deletion mutant (preS2ΔMT) on hepatocyte damage in vitro and liver fibrosis in vivo., Approach and Results: Association of preS mutations with HCC in 343 patients with CHB was evaluated by a retrospective case-control follow-up study. Effects of preS2ΔMT on HBsAg retention, endoplasmic reticulum (ER) stress, calcium accumulation, mitochondrial dysfunction, and liver fibrosis were examined. Multivariate analysis revealed a significant association of preS mutations with HCC (HR, 3.210; 95% CI, 1.072-9.613; P = 0.037) including cases with low HBV DNA or ALT levels (HR, 2.790; 95% CI, 1.133-6.873; P = 0.026). Antiviral therapy reduced HCC risk, including cases with preS mutations. PreS2ΔMT expression promoted HBsAg retention in the ER and unfolded protein response (UPR). Transmission electron microscopic examination, MitoTracker staining, real-time ATP assay, and calcium staining of preS2ΔMT-expressing cells revealed aberrant ER and mitochondrial ultrastructure, reduction of mitochondrial membrane potential and ATP production, and calcium overload. Serum HBV secretion levels were ~100-fold lower in preS2ΔMT-infected humanized Fah-/-/ Rag2-/-/Il2rg-/- triple knockout mice than in wild-type HBV-infected mice. PreS2ΔMT-infected mice displayed up-regulation of UPR and caspase-3 and enhanced liver fibrosis., Conclusions: PreS mutations were significantly associated with HCC development in patients with CHB, including those with low HBV DNA or ALT levels. Antiviral therapy reduced HCC occurrence in patients with CHB, including those with preS mutations. Intracellular accumulation of mutated HBsAg induced or promoted ER stress, calcium overload, mitochondrial dysfunction, impaired energy metabolism, liver fibrosis, and HCC., (© 2021 by the American Association for the Study of Liver Diseases.)

Background and Aims: Bacterial infections are common and severe in cirrhosis, but their pathogenesis is poorly understood. Dysfunction of liver macrophages may play a role, but information about their function in cirrhosis is limited. Our aims were to investigate the specific profile and function of liver macrophages in cirrhosis and their contribution to infections. Macrophages from human cirrhotic livers were characterized phenotypically by transcriptome analysis and flow cytometry; function was assessed in vivo by single photon emission computerized tomography in patients with cirrhosis. Serum levels of specific proteins and expression in peripheral monocytes were determined by ELISA and flow cytometry. In vivo phagocytic activity of liver macrophages was measured by spinning disk intravital microscopy in a mouse model of chronic liver injury., Approach and Results: Liver macrophages from patients with cirrhosis overexpressed proteins related to immune exhaustion, such as programmed death ligand 1 (PD-L1), macrophage receptor with collagenous structure (MARCO), and CD163. In vivo phagocytic activity of liver macrophages in patients with cirrhosis was markedly impaired. Monocytes from patients with cirrhosis showed overexpression of PD-L1 that paralleled disease severity, correlated with its serum levels, and was associated with increased risk of infections. Blockade of PD-L1 with anti-PD-L1 antibody caused a shift in macrophage phenotype toward a less immunosuppressive profile, restored liver macrophage in vivo phagocytic activity, and reduced bacterial dissemination., Conclusion: Liver cirrhosis is characterized by a remarkable impairment of phagocytic function of macrophages associated with an immunosuppressive transcriptome profile. The programmed cell death receptor 1/PD-L1 axis plays a major role in the impaired activity of liver macrophages. PD-L1 blockade reverses the immune suppressive profile and increases antimicrobial activity of liver macrophages in cirrhosis., (© 2020 The Authors. Hepatology published by Wiley Periodicals LLC on behalf of American Association for the Study of Liver Diseases.)

Background Ands Aims: NAFLD is associated with elevation of many cytokines, particularly IL-6; however, the role of IL-6 in NAFLD remains obscure. The aim of this study was to examine how myeloid-specific IL-6 signaling affects NAFLD by the regulation of antifibrotic microRNA-223 (miR-223) in myeloid cells., Approach and Results: Patients with NAFLD or NASH and healthy controls were recruited, and serum IL-6 and soluble IL-6 receptor α (sIL-6Rα) were measured. Compared to controls, serum IL-6 and sIL-6Rα levels were elevated in NAFLD/NASH patients. IL-6 levels correlated positively with the number of circulating leukocytes and monocytes. The role of IL-6 in NAFLD was investigated in Il6 knockout (KO) and Il6 receptor A (Il6ra) conditional KO mice after high-fat diet (HFD) feeding. HFD-fed Il6 KO mice had worse liver injury and fibrosis, but less inflammation, compared to wild-type mice. Hepatocyte-specific Il6ra KO mice had more steatosis and liver injury, whereas myeloid-specific Il6ra KO mice had a lower number of hepatic infiltrating macrophages (IMs) and neutrophils with increased cell death of these cells, but greater liver fibrosis (LF), than WT mice. Mechanistically, the increased LF in HFD-fed, myeloid-specific Il6ra KO mice was attributable to the reduction of antifibrotic miR-223 and subsequent up-regulation of the miR-223 target gene, transcriptional activator with PDZ-binding motif (TAZ), a well-known factor to promote NASH fibrosis. In vitro, IL-6 treatment up-regulated exosome biogenesis-related genes and subsequently promoted macrophages to release miR-223-enriched exosomes that were able to reduce profibrotic TAZ expression in hepatocytes by exosomal transfer. Finally, serum IL-6 and miR-223 levels were elevated and correlated with each other in NAFLD patients., Conclusions: Myeloid-specific IL-6 signaling inhibits LF through exosomal transfer of antifibrotic miR-223 into hepatocytes, providing therapeutic targets for NAFLD therapy., (© 2020 by the American Association for the Study of Liver Diseases.)

Background and Aims: It is well accepted that liver diseases and their outcomes are associated with intestinal microbiota, but causality is difficult to establish. The intestinal microbiota are altered in patients with hepatitis C. As chronic HCV infection can now be cured in almost all patients, it is an ideal model to study the influence of liver disease on the microbiota., Approach and Results: We aimed to prospectively analyze the changes in the gut microbiome in patients who received direct-acting antivirals (DAA) and achieved sustained virological response (SVR). Amplicon sequencing of the V1-V2 region in the 16S ribosomal RNA gene was performed in stool samples of patients with chronic hepatitis C. Patients in the treatment group received DAA (n = 65), whereas in the control group, no DAA were given (n = 33). Only patients achieving SVR were included. The alpha diversity increased numerically but not significantly from baseline to SVR at week 24 or 48 (SVR24/48; 2.784 ± 0.248 vs. 2.846 ± 0.224; P = 0.057). When stratifying for the presence of liver cirrhosis, a significant increase in diversity was only seen in patients without cirrhosis. Differences in the microbial community structure induced by the achievement of SVR were only observed in patients without liver cirrhosis. In patients with liver cirrhosis and in the control group, no significant differences were observed., Conclusions: In conclusion, the achievement of SVR24/48 in patients with chronic HCV was associated with changes in the intestinal microbiota. However, these changes were only seen in patients without liver cirrhosis. A major role of liver remodeling on the intestinal microbiota is indicated by the dynamics of the intestinal microbial community structure depending on the stage of fibrosis in patients resolving chronic hepatitis C., (© 2021 The Authors. Hepatology published by Wiley Periodicals LLC on behalf of American Association for the Study of Liver Diseases.)

Background and Aims: Nonalcoholic fatty liver disease (NAFLD) is simple steatosis but can develop into nonalcoholic steatohepatitis (NASH), characterized by liver inflammation, fibrosis, and microvesicular steatosis. Mast cells (MCs) infiltrate the liver during cholestasis and promote ductular reaction (DR), biliary senescence, and liver fibrosis. We aimed to determine the effects of MC depletion during NAFLD/NASH., Approach and Results: Wild-type (WT) and Kit W-sh (MC-deficient) mice were fed a control diet (CD) or a Western diet (WD) for 16 weeks; select WT and Kit W-sh WD mice received tail vein injections of MCs 2 times per week for 2 weeks prior to sacrifice. Human samples were collected from normal, NAFLD, or NASH mice. Cholangiocytes from WT WD mice and human NASH have increased insulin-like growth factor 1 expression that promotes MC migration/activation. Enhanced MC presence was noted in WT WD mice and human NASH, along with increased DR. WT WD mice had significantly increased steatosis, DR/biliary senescence, inflammation, liver fibrosis, and angiogenesis compared to WT CD mice, which was significantly reduced in Kit W-sh WD mice. Loss of MCs prominently reduced microvesicular steatosis in zone 1 hepatocytes. MC injection promoted WD-induced biliary and liver damage and specifically up-regulated microvesicular steatosis in zone 1 hepatocytes. Aldehyde dehydrogenase 1 family, member A3 (ALDH1A3) expression is reduced in WT WD mice and human NASH but increased in Kit W-sh WD mice. MicroRNA 144-3 prime (miR-144-3p) expression was increased in WT WD mice and human NASH but reduced in Kit W-sh WD mice and was found to target ALDH1A3., Conclusions: MCs promote WD-induced biliary and liver damage and may promote microvesicular steatosis development during NAFLD progression to NASH through miR-144-3p/ALDH1A3 signaling. Inhibition of MC activation may be a therapeutic option for NAFLD/NASH treatment., (© 2021 by the American Association for the Study of Liver Diseases.)

Background and Aims: T cells from patients with primary sclerosing cholangitis (PSC) show a prominent interleukin (IL)-17 response upon stimulation with bacteria or fungi, yet the reasons for this dominant T-helper 17 (Th17) response in PSC are not clear. Here, we analyzed the potential role of monocytes in microbial recognition and in skewing the T-cell response toward Th17., Approach and Results: Monocytes and T cells from blood and livers of PSC patients and controls were analyzed ex vivo and in vitro using transwell experiments with cholangiocytes. Cytokine production was measured using flow cytometry, enzyme-linked immunosorbent assay, RNA in situ hybridization, and quantitative real-time PCR. Genetic polymorphisms were obtained from ImmunoChip analysis. Following ex vivo stimulation with phorbol myristate acetate/ionomycin, PSC patients showed significantly increased numbers of IL-17A-producing peripheral blood CD4 + T cells compared to PBC patients and healthy controls, indicating increased Th17 differentiation in vivo. Upon stimulation with microbes, monocytes from PSC patients produced significantly more IL-1β and IL-6, cytokines known to drive Th17 cell differentiation. Moreover, microbe-activated monocytes induced the secretion of Th17 and monocyte-recruiting chemokines chemokine (C-C motif) ligand (CCL)-20 and CCL-2 in human primary cholangiocytes. In livers of patients with PSC cirrhosis, CD14 hi CD16 int and CD14 lo CD16 hi monocytes/macrophages were increased compared to alcoholic cirrhosis, and monocytes were found to be located around bile ducts., Conclusions: PSC patients show increased Th17 differentiation already in vivo. Microbe-stimulated monocytes drive Th17 differentiation in vitro and induce cholangiocytes to produce chemokines mediating recruitment of Th17 cells and more monocytes into portal tracts. Taken together, these results point to a pathogenic role of monocytes in patients with PSC., (© The Authors. Hepatology published by Wiley Periodicals, Inc., on behalf of American Association for the Study of Liver Diseases.)

Background and Aims: Patients with advanced liver cirrhosis have an increased susceptibility to infections. As part of the cirrhosis-associated immune dysfunction, mucosal-associated invariant T (MAIT) cells, which have the capacity to respond to bacteria, are severely diminished in circulation and liver tissue. However, MAIT cell presence and function in the peritoneal cavity, a common anatomical site for infections in cirrhosis, remain elusive. In this study, we deliver a comprehensive investigation of the immune compartment present in ascites of patients with decompensated liver cirrhosis, and focus especially on MAIT cells., Approach and Results: To study this, matched peripheral blood and ascites fluid were collected from 35 patients with decompensated cirrhosis, with or without spontaneous bacterial peritonitis (SBP). MAIT cell phenotype and function were analyzed using high-dimensional flow cytometry, and the obtained data were compared with the blood samples of healthy controls (n = 24) and patients with compensated cirrhosis (n = 11). We found circulating MAIT cells to be severely decreased in patients with cirrhosis as compared with controls. In contrast, in ascites fluid, MAIT cells were significantly increased together with CD14 + CD16 + monocytes, innate lymphoid cells, and natural killer cells. This was paralleled by elevated levels of several pro-inflammatory cytokines and chemokines in ascites fluid as compared with plasma. Peritoneal MAIT cells displayed an activated tissue-resident phenotype, and this was corroborated by increased functional responses following stimulation with E. coli or interleukin (lL)-12 + IL-18 as compared with circulating MAIT cells. During SBP, peritoneal MAIT cell frequencies increased most among all major immune cell subsets, suggestive of active homing of MAIT cells to the site of infection., Conclusions: Despite severely diminished MAIT cell numbers and impaired phenotype in circulation, peritoneal MAIT cells remain abundant, activated, and highly functional in decompensated cirrhosis and are further enriched in SBP. This suggests that peritoneal MAIT cells could be of interest for immune-intervention strategies in patients with decompensated liver cirrhosis and SBP., (© 2020 The Authors. Hepatology published by Wiley Periodicals, Inc., on behalf of American Association for the Study of Liver Diseases.)

Autoimmune liver diseases (AILDs) are chronic liver pathologies characterized by fibrosis and cirrhosis due to immune-mediated liver damage. In this study, we addressed the question whether mucosal-associated invariant T (MAIT) cells, innate-like T cells, are functionally altered in patients with AILD and whether MAIT cells can promote liver fibrosis through activation of hepatic stellate cells (HSCs). We analyzed the phenotype and function of MAIT cells from AILD patients and healthy controls by multicolor flow cytometry and investigated the interaction between human MAIT cells and primary human hepatic stellate cells (hHSCs). We show that MAIT cells are significantly decreased in peripheral blood and liver tissue of patients with AILD. Notably, MAIT cell frequency tended to decrease with increasing fibrosis stage. MAIT cells from AILD patients showed signs of exhaustion, such as impaired interferon-γ (IFN-γ) production and high ex vivo expression of the activation and exhaustion markers CD38, HLA-DR, and CTLA-4. Mechanistically, this exhausted state could be induced by repetitive stimulation of MAIT cells with the cytokines interleukin (IL)-12 and IL-18, leading to decreased IFN-γ and increased exhaustion marker expression. Of note, repetitive stimulation with IL-12 further resulted in expression of the profibrogenic cytokine IL-17A by otherwise exhausted MAIT cells. Accordingly, MAIT cells from both healthy controls and AILD patients were able to induce an activated, proinflammatory and profibrogenic phenotype in hHSCs in vitro that was partly mediated by IL-17., Conclusion: Our data provide evidence that MAIT cells in AILD patients have evolved towards an exhausted, profibrogenic phenotype and can contribute to the development of HSC-mediated liver fibrosis. These findings reveal a cellular and molecular pathway for fibrosis development in AILD that could be exploited for antifibrotic therapy. (Hepatology 2018;68:172-186)., (© 2018 by the American Association for the Study of Liver Diseases.)

Hepatocellular carcinoma (HCC) is a frequent neoplasia and a leading cause of inflammation-related cancer mortality. Despite that most HCCs arise from persistent inflammatory conditions, pathways linking chronic inflammation to cancer development are still incompletely elucidated. We dissected the role of adaptive immunity in the Mdr2 knockout (Mdr2 -/- ) mouse, a model of inflammation-associated cancer, in which ablation of adaptive immunity has been induced genetically (Rag2 -/- Mdr2 -/- and μMt-Mdr2 -/- mice) or with in vivo treatments using lymphocyte-specific depleting antibodies (anti-CD20 or anti-CD4/CD8). We found that activated B and T lymphocytes, secreting fibrogenic tumor necrosis factor alpha (TNFα) and other proinflammatory cytokines, infiltrated liver of the Mdr2 -/- mice during chronic fibrosing cholangitis. Lymphocyte ablation, in the Rag2 -/- Mdr2 -/- and μMt-Mdr2 -/- mice, strongly suppressed hepatic stellate cell (HSC) activation and extracellular matrix deposition, enhancing HSC transition to cellular senescence. Moreover, lack of lymphocytes changed the intrahepatic metabolic/oxidative state, resulting in skewed macrophage polarization toward an anti-inflammatory M2 phenotype. Remarkably, hepatocarcinogenesis was significantly suppressed in the Rag2 -/- Mdr2 -/- mice, correlating with reduced TNFα/NF-κB (nuclear factor kappa B) pathway activation. Ablation of CD20 + B cells, but not of CD4 + /CD8 + T cells, in Mdr2 -/- mice, promoted senescence-mediated fibrosis resolution and inhibited the protumorigenic TNFα/NF-κB pathway. Interestingly, presence of infiltrating B cells correlated with increased tumor aggressiveness and reduced disease-free survival in human HCC., Conclusion: Adaptive immunity sustains liver fibrosis (LF) and favors HCC growth in chronic injury, by modulating innate components of inflammation and limiting the extent of HSC senescence. Therapies designed for B-cell targeting may be an effective strategy in LF. (Hepatology 2018;67:1970-1985)., (© 2017 by the American Association for the Study of Liver Diseases.)

Persistent hepatotropic viral infections are a common etiologic agent of chronic liver disease. Unresolved infection can be attributed to nonfunctional intrahepatic CD8+ T-cell responses. In light of dampened CD8 + T-cell responses, liver disease often manifests systemically as immunoglobulin (Ig)-related syndromes due to aberrant B-cell functions. These two opposing yet coexisting phenomena implicate the potential of altered CD4 + T-cell help. Elevated CD4 + forkhead box P3-positive (Foxp3+) T cells were evident in both human liver disease and a mouse model of chemically induced liver injury despite marked activation and spontaneous IgG production by intrahepatic B cells. While this population suppressed CD8 + T-cell responses, aberrant B-cell activities were maintained due to expression of CD40 ligand on a subset of CD4 + Foxp3+ T cells. In vivo blockade of CD40 ligand attenuated B-cell abnormalities in a mouse model of liver injury. A phenotypically similar population of CD4 + Foxp3+, CD40 ligand-positive T cells was found in diseased livers explanted from patients with chronic hepatitis C infection. This population was absent in nondiseased liver tissues and peripheral blood., Conclusion: Liver disease elicits alterations in the intrahepatic CD4 + T-cell compartment that suppress T-cell immunity while concomitantly promoting aberrant IgG mediated manifestations. (Hepatology 2017;65:661-677)., Competing Interests: The authors have no conflicts of interest to disclose., (© 2016 by the American Association for the Study of Liver Diseases.)

Unlabelled: Congenital hepatic fibrosis (CHF) is a disease of the biliary epithelium characterized by bile duct changes resembling ductal plate malformations and by progressive peribiliary fibrosis, in the absence of overt necroinflammation. Progressive liver fibrosis leads to portal hypertension and liver failure; however, the mechanisms leading to fibrosis in CHF remain elusive. CHF is caused by mutations in PKHD1, a gene encoding for fibrocystin, a ciliary protein expressed in cholangiocytes. Using a fibrocystin-defective (Pkhd1(del4/del4)) mouse, which is orthologous of CHF, we show that Pkhd1(del4/del4) cholangiocytes are characterized by a β-catenin-dependent secretion of a range of chemokines, including chemokine (C-X-C motif) ligands 1, 10, and 12, which stimulate bone marrow-derived macrophage recruitment. We also show that Pkhd1(del4/del4) cholangiocytes, in turn, respond to proinflammatory cytokines released by macrophages by up-regulating αvβ6 integrin, an activator of latent local transforming growth factor-β1. While the macrophage infiltrate is initially dominated by the M1 phenotype, the profibrogenic M2 phenotype increases with disease progression, along with the number of portal myofibroblasts. Consistent with these findings, clodronate-induced macrophage depletion results in a significant reduction of portal fibrosis and portal hypertension as well as of liver cysts., Conclusion: Fibrosis can be initiated by an epithelial cell dysfunction, leading to low-grade inflammation, macrophage recruitment, and collagen deposition; these findings establish a new paradigm for biliary fibrosis and represent a model to understand the relationship between cell dysfunction, parainflammation, liver fibrosis, and macrophage polarization over time., (© 2015 by the American Association for the Study of Liver Diseases.)

Unlabelled: Chronic liver disease mediated by activation of hepatic stellate cells (HSCs) leads to liver fibrosis. Here, we postulated that the immune regulatory properties of HSCs might promote the profibrogenic activity of B cells. Fibrosis is completely attenuated in carbon tetrachloride-treated, B cell-deficient µMT mice, showing that B cells are required. The retinoic acid produced by HSCs augmented B-cell survival, plasma cell marker CD138 expression, and immunoglobulin G production. These activities were reversed following addition of the retinoic acid inhibitor LE540. Transcriptional profiling of fibrotic liver B cells revealed increased expression of genes related to activation of nuclear factor κ light chain enhancer of activated B cells, proinflammatory cytokine production, and CD40 signaling, suggesting that these B cells are activated and may be acting as inflammatory cells. Biological validation experiments also revealed increased activation (CD44 and CD86 expression), constitutive immunoglobulin G production, and secretion of the proinflammatory cytokines tumor necrosis factor-α, monocyte chemoattractant protein-1, and macrophage inflammatory protein-1α. Likewise, targeted deletion of B-cell-intrinsic myeloid differentiation primary response gene 88 signaling, an innate adaptor with involvement in retinoic acid signaling, resulted in reduced infiltration of migratory CD11c(+) dendritic cells and Ly6C(++) monocytes and, hence, reduced liver pathology., Conclusion: Liver fibrosis occurs through a mechanism of HSC-mediated augmentation of innate B-cell activity. These findings highlight B cells as important "first responders" of the intrahepatic immune environment., (© 2015 by the American Association for the Study of Liver Diseases.)

Unlabelled: Macrophages play multidimensional roles in hepatic fibrosis, but their control has not been fully understood. The Notch pathway mediated by recombination signal binding protein Jκ (RBP-J), the transcription factor transactivated by signals from four mammalian Notch receptors, is implicated in macrophage activation and plasticity. In this study, by using mouse hepatic fibrosis models, we show that myeloid-specific disruption of RBP-J resulted in attenuated fibrosis. The activation of hepatic stellate cells and production of profibrotic factors including platelet-derived growth factor (PDGF)-B and transforming growth factor beta1 (TGF-β1) reduced significantly in myeloid-specific RBP-J deficient mice. The infiltration of inflammatory cells and production of proinflammatory factors were reduced in liver of myeloid-specific RBP-J-deficient mice during fibrosis. In RBP-J-deficient macrophages, the nuclear factor kappa B (NF-κB) activation was remarkably attenuated as compared with the control. This could be attributed to the up-regulation of cylindromatosis (CYLD), a negative regulator of NF-κB, in Notch signal-compromised macrophages, because the knockdown of CYLD in RBP-J-deficient macrophages or overexpression of p65 in RBP-J knockdown cells both restored NF-κB activation and the production of proinflammatory and/or profibrotic factors by macrophages. In human hepatic fibrosis biopsies, stronger Notch activation is correlated with more severe fibrosis, which is accompanied by a lower level of CYLD but irrespective of etiological reasons., Conclusion: RBP-J-mediated Notch signaling is required for macrophages to promote hepatic fibrosis by up-regulation of NF-κB activation through CYLD., (© 2014 by the American Association for the Study of Liver Diseases.)

Unlabelled: Chronic hepatitis C virus (HCV) infection is characterized by progressive hepatic fibrosis, a process dependent on monocyte recruitment and accumulation into the liver. The mediators expressed in chronically injured liver that control the differentiation of human monocytes into profibrotic macrophages (Mφ) remain poorly defined. We report that chronically HCV-infected patients with high fibrosis stages have higher serum levels of macrophage colony-stimulating factor (M-CSF) and interleukin (IL)-34 than HCV-infected patients with lower fibrosis stages and healthy subjects. Immunohistochemistry reveals an intense expression of IL-34 and M-CSF by hepatocytes around liver lesions. In addition, HCV infection and inflammatory cytokines enhance the in vitro production of IL-34 and M-CSF by hepatocytes. We next analyzed the acquisition of profibrotic properties by Mφ generated with M-CSF (M-CSF-Mφ) or IL-34 (IL-34-Mφ). M-CSF and IL-34 up-regulate the expression, by differentiating monocytes, of chemokine (C-C motif) ligand (CCL)2, CCL4, C-C chemokine receptor (CCR)1, and CCR5, which are involved in monocyte recruitment/Mφ accumulation in liver lesions. M-CSF-Mφ and IL-34-Mφ also express the hepatic stellate cell (HSC) activators, platelet-derived growth factor, transforming growth factor beta, and galectin-3. IL-34-Mφ and M-CSF-Mφ induce type I collagen synthesis by HSCs, the main collagen-producing cells in liver fibrosis. IL-13, whose expression correlates with the fibrosis stage in HCV-infected patients, decreases the expression of the collagenase, matrix metalloproteinase 1, by IL-34-Mφ and M-CSF-Mφ, thereby enhancing collagen synthesis. By inhibiting the production of interferon-gamma (IFN-γ) by activated natural killer cells, IL-34-Mφ and M-CSF-Mφ prevent the IFN-γ-induced killing of HSCs., Conclusion: These results identify M-CSF and IL-34 as potent profibrotic factors in HCV liver fibrosis., (© 2014 by the American Association for the Study of Liver Diseases.)

Unlabelled: Chronic hepatic diseases, such as cirrhosis, hepatocellular carcinoma, and virus-mediated immunopathogenic infections, affect billions of people worldwide. These diseases commonly initiate with fibrosis. Owing to the various side effects of antifibrotic therapy and the difficulty of diagnosing asymptomatic patients, suitable medication remains a major concern. To overcome this drawback, the use of cytokine-based sustained therapy might be a suitable alternative with minimal side effects. Here, we studied the therapeutic efficacy and potential mechanisms of interleukin (IL)-30 as antifibrosis therapy in murine liver fibrosis models. CCl4 or 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) 0.1% (wt/wt) Purina 5015 Chow (LabDiet, St. Louis, MO) was fed for 3 weeks to induce liver fibrosis. Either control vector (pCtr) or pIL30 was injected hydrodynamically once per week. A significant decrease in collagen deposition and reduced expression of alpha-smooth muscle actin (α-SMA) protein indicated that IL-30-based gene therapy dramatically reduced bridging fibrosis that was induced by CCl4 or DDC. Immunophenotyping and knockout studies showed that IL-30 recruits natural-killer-like T (NKT) cells to the liver to remove activated hepatic stellate cells (HSCs) significantly and ameliorate liver fibrosis. Both flow cytometric and antibody-mediated neutralization studies showed that liver NKT cells up-regulate the natural killer group 2, member D (NKG2D) ligand and bind with the NKG2D ligand, retinoic acid early inducible 1 (Rae1), and positively activated HSCs to ameliorate liver fibrosis. Furthermore, adoptive transfer of liver NKT cells in T-cell-deficient mice showed reduction of fibrosis upon IL-30 administration., Conclusions: Highly target-specific liver NKT cells selectively remove activated HSCs through an NKG2D-Rae1 interaction to ameliorate liver fibrosis after IL-30 treatment., (© 2014 by the American Association for the Study of Liver Diseases.)

Unlabelled: Regulatory T cells (Tregs) can be considered as a mixed population of distinct subsets, endowed with a diverse extent and quality of adaptation to microenvironmental signals. Here, we uncovered an opposite distribution of Treg expansion, phenotype, and plasticity in different microenvironments in the same organ (liver) derived from patients with chronic hepatitis C: On the one side, cirrhotic and tumor fragments were moderately and highly infiltrated by Tregs, respectively, expressing OX40 and a T-bethigh IFN-γ- "T-helper (Th)1-suppressing" phenotype; on the other side, noncirrhotic liver specimens contained low frequencies of Tregs that expressed low levels of OX40 and highly produced interferon-gamma (IFN-γ; T-bet+IFN-γ+), thus becoming "Th1-like" cells. OX40-expressing and Th1-suppressing Tregs were enriched in the Helios-positive subset, carrying highly demethylated Treg cell-specific demethylated region that configures committed Tregs stably expressing forkhead box protein 3. OX40 ligand, mostly expressed by M2-like monocytes and macrophages, boosted OX40+ Treg proliferation and antagonized the differentiation of Th1-like Tregs. However, this signal is counteracted in noncirrhotic liver tissue (showing various levels of inflammation) by high availability of interleukin-12 and IFN-γ, ultimately leading to complete, full Th1-like Treg differentiation., Conclusion: Our data demonstrate that Tregs can finely adapt, or even subvert, their classical inhibitory machinery in distinct microenvironments within the same organ., (© 2014 by the American Association for the Study of Liver Diseases.)

Unlabelled: The important roles of retinols and their metabolites have recently been emphasized in the interactions between hepatic stellate cells (HSCs) and natural killer (NK) cells. Nevertheless, the expression and role of retinol metabolizing enzyme in both cell types have yet to be clarified. Thus, we investigated the expression of retinol metabolizing enzyme and its role in liver fibrosis. Among several retinol metabolizing enzymes, only alcohol dehydrogenase (ADH) 3 expression was detected in isolated HSCs and NK cells, whereas hepatocytes express all of them. In vitro treatment with 4-methylpyrazole (4-MP), a broad ADH inhibitor, or depletion of the ADH3 gene down-regulated collagen and transforming growth factor-β1 (TGF-β1) gene expression, but did not affect α-smooth muscle actin gene expression in cultured HSCs. Additionally, in vitro, treatments with retinol suppressed NK cell activities, whereas inhibition of ADH3 enhanced interferon-γ (IFN-γ) production and cytotoxicity of NK cells against HSCs. In vivo, genetic depletion of the ADH3 gene ameliorated bile duct ligation- and carbon tetrachloride-induced liver fibrosis, in which a higher number of apoptotic HSCs and an enhanced activation of NK cells were detected. Freshly isolated HSCs from ADH3-deficient mice showed reduced expression of collagen and TGF-β1, but enhanced expression of IFN-γ was detected in NK cells from these mice compared with those of control mice. Using reciprocal bone marrow transplantation of wild-type and ADH3-deficient mice, we demonstrated that ADH3 deficiency in both HSCs and NK cells contributed to the suppressed liver fibrosis., Conclusion: ADH3 plays important roles in promoting liver fibrosis by enhancing HSC activation and inhibiting NK cell activity, and could be used as a potential therapeutic target for the treatment of liver fibrosis., (© 2014 by the American Association for the Study of Liver Diseases.)

Unlabelled: Interleukin (IL)-20 is a proinflammatory cytokine of the IL-10 family and involved in rheumatoid arthritis, atherosclerosis, stroke, and osteoporosis. However, the pathophysiological roles of IL-20 in liver injury have not been extensively studied. We explored the involvement of IL-20 in liver injury and the therapeutic potential of IL-20 antagonists for treating liver fibrosis. Compared with normal liver tissue from healthy individuals, the amount of IL-20 was much higher in hepatocytes and hepatic stellate cells in liver biopsies from patients with fibrosis, cirrhosis, and hepatocellular carcinoma. Carbon tetrachloride (CCl4) treatment induced IL-20 that further up-regulated the expression of transforming growth factor (TGF)-β1 and p21(WAF1) and resulted in cell cycle arrest in the Clone-9 rat hepatocyte cell line. IL-20 activated quiescent rat hepatic stellate cells (HSCs) and up-regulated TGF-β1 expression. IL-20 also increased TGF-β1, tumor necrosis factor (TNF)-α, and type I collagen (Col-I) expression, and promoted the proliferation and migration of activated HSCs. Serum IL-20 was significantly elevated in mice with short-term and long-term CCl4 -induced liver injury. In mice with short-term liver injury, anti-IL-20 monoclonal antibody (7E) and anti-IL-20 receptor (IL-20R1) monoclonal antibody (51D) attenuated hepatocyte damage caused by CCl4, TGF-β1, and chemokine production. In mice with long-term liver injury, 7E and 51D inhibited CCl4 -induced cell damage, TGF-β1 production, liver fibrosis, HSC activation, and extracellular matrix accumulation, which was caused by the reduced expression of tissue inhibitors of metalloproteinases as well as increased metalloproteinase expression and Col-I production. IL-20R1-deficient mice were protected from short-term and long-term liver injury., Conclusion: We identified a pivotal role of IL-20 in liver injury and showed that 7E and 51D may be therapeutic for liver fibrosis., (© 2014 by the American Association for the Study of Liver Diseases.)

Unlabelled: Annexin A1 (AnxA1) is an effector of the resolution of inflammation and is highly effective in terminating acute inflammatory responses. However, its role in chronic settings is less investigated. Because changes in AnxA1 expression within adipose tissue characterize obesity in mice and humans, we queried a possible role for AnxA1 in the pathogenesis of nonalcoholic steatohepatitis (NASH), a disease commonly associated with obesity. NASH was induced in wild-type (WT) and AnxA1 knockout (AnxA1 KO) C57BL/6 mice by feeding a methionine-choline deficient (MCD) diet up to 8 weeks. In MCD-fed WT mice, hepatic AnxA1 increased in parallel with progression of liver injury. This mediator was also detected in liver biopsies from patients with NASH and its degree of expression inversely correlated with the extent of fibrosis. In both humans and rodents, AnxA1 production was selectively localized in liver macrophages. NASH in AnxA1 KO mice was characterized by enhanced lobular inflammation resulting from increased macrophage recruitment and exacerbation of the M1 phenotype. Consistently, in vitro addition of recombinant AnxA1 to macrophages isolated from NASH livers down-modulated M1 polarization through stimulation of interleukin-10 production. Furthermore, the degree of hepatic fibrosis was enhanced in MCD-fed AnxA1 KO mice, an effect associated with augmented liver production of the profibrotic lectin, galectin-3. Accordingly, AnxA1 addition to isolated hepatic macrophages reduced galectin-3 expression., Conclusions: Macrophage-derived AnxA1 plays a functional role in modulating hepatic inflammation and fibrogenesis during NASH progression, suggesting the possible use of AnxA1 analogs for therapeutic control of this disease., (© 2014 The Authors. Hepatology published by Wiley on behalf of the American Association for the Study of Liver Diseases.)

Unlabelled: Toll-like receptor 7 (TLR7) signaling predominantly regulates production of type I interferons (IFNs), which has been suggested in clinical studies to be antifibrotic. However, the mechanistic role of the TLR7-type I IFN axis in liver fibrosis has not been elucidated. In the present study, liver fibrosis was induced in wild-type (WT), TLR7-deficient, and IFN-α/β receptor-1 (IFNAR1)-deficient mice and TLR7-mediated signaling was assessed in liver cells isolated from these mice. TLR7-deficient and IFNAR1-deficient mice were more susceptible to liver fibrosis than WT mice, indicating that TLR7-type I IFN signaling exerts a protective effect against liver fibrosis. Notably, the hepatic expression of interleukin-1 receptor antagonist (IL-1ra) was suppressed in TLR7- or IFNAR1-deficient mice compared with respective WT mice, and treatment with recombinant IL-1ra reduced liver fibrosis. In vivo activation of TLR7 significantly increased IFNa4 and IL-1ra expression in the liver. Interestingly, each cytokine had a different cellular source, showing that dendritic cells (DCs) are the responsible cell type for production of type I IFN, while Kupffer cells (KCs) mainly produce IL-1ra in response to type I IFN. Furthermore, TLR7 activation by R848 injection suppressed liver fibrosis and production of proinflammatory cytokines, and these effects were dependent on type I IFN signaling. Consistent with in vivo data, IFN-α significantly induced IL-1ra production in primary KCs., Conclusion: TLR7 signaling activates DCs to produce type I IFN, which in turn induces antifibrogenic IL-1ra production in KCs. Thus, manipulation of the TLR7-type I IFN-IL-1ra axis may be a new therapeutic strategy for the treatment of liver fibrosis., (© 2014 by the American Association for the Study of Liver Diseases.)

Unlabelled: Inflammasome activation plays a central role in the development of drug-induced and obesity-associated liver disease. However, the sources and mechanisms of inflammasome-mediated liver damage remain poorly understood. Our aim was to investigate the effect of NLRP3 inflammasome activation on the liver using novel mouse models. We generated global and myeloid cell-specific conditional mutant Nlrp3 knock-in mice expressing the D301N Nlrp3 mutation (ortholog of D303N in human NLRP3), resulting in a hyperactive NLRP3. To study the presence and significance of NLRP3-initiated pyroptotic cell death, we separated hepatocytes from nonparenchymal cells and developed a novel flow-cytometry-based (fluorescence-activated cell sorting; FACS) strategy to detect and quantify pyroptosis in vivo based on detection of active caspase 1 (Casp1)- and propidium iodide (PI)-positive cells. Liver inflammation was quantified histologically by FACS and gene expression analysis. Liver fibrosis was assessed by Sirius Red staining and quantitative polymerase chain reaction for markers of hepatic stellate cell (HSC) activation. NLRP3 activation resulted in shortened survival, poor growth, and severe liver inflammation; characterized by neutrophilic infiltration and HSC activation with collagen deposition in the liver. These changes were partially attenuated by treatment with anakinra, an interleukin-1 receptor antagonist. Notably, hepatocytes from global Nlrp3-mutant mice showed marked hepatocyte pyroptotic cell death, with more than a 5-fold increase in active Casp1/PI double-positive cells. Myeloid cell-restricted mutant NLRP3 activation resulted in a less-severe liver phenotype in the absence of detectable pyroptotic hepatocyte cell death., Conclusions: Our data demonstrate that global and, to a lesser extent, myeloid-specific NLRP3 inflammasome activation results in severe liver inflammation and fibrosis while identifying hepatocyte pyroptotic cell death as a novel mechanism of NLRP3-mediated liver damage., (© 2014 by the American Association for the Study of Liver Diseases.)

Unlabelled: The rationale for screening inflammatory serum biomarkers of the hepatic vein pressure gradient (HVPG) is based on the fact that portal hypertension is pathogenically related to liver injury and fibrosis, and that in turn these are associated with the activation of inflammatory pathways. This was a nested cohort study in the setting of a randomized, clinical trial to assess the development of gastroesophageal varices (GEV) (N Engl J Med 2005;353:2254). Patients had cirrhosis and portal hypertension but did not have GEV. A total of 90 patients who had baseline day-1 sera available were enrolled in the present study. The objective of this study was to determine whether inflammatory biomarkers in conjunction with clinical parameters could be used to develop a predictive paradigm for HVPG. The correlations between HVPG and interleukin (IL)-1β (P=0.0052); IL-1R-α (P=0.0085); Fas-R (P=0.0354), and serum VCAM-1 (P=0.0007) were highly significant. By using multivariate logistic regression analysis and selected parameters (transforming growth factor beta [TGFβ]; heat shock protein [HSP]-70; at-risk alcohol use; and Child class B) we could exclude HVPG ≥ 12 mmHg with 86% accuracy (95% confidence interval [CI]: 67.78 to 96.16%) and the sensitivity was 87.01% (95% CI: 69.68 to 96.34%). Therefore, the composite test could identify 86% of compensated cirrhosis patients with HVPG below 12 mmHg and prevent unnecessary esophagogastroduodenoscopy with its associated morbidity and costs in these patients. Our diagnostic test was not efficient in predicting HVPG ≥ 12 mmHg., Conclusion: A blood test for HVPG could be performed in cirrhosis patients to prevent unnecessary esophagogastroduodenoscopy., (© 2014 by the American Association for the Study of Liver Diseases.)

Unlabelled: Macrophages constitute a major proinflammatory component during chronic liver diseases and are considered a key factor in promoting hepatic fibrosis. However, there is increasing evidence that distinct monocyte and macrophage subsets exert critical functions in regression from organ fibrosis as well. Experimental mouse models of fibrosis regression have identified "restorative" macrophages as Ly-6C (Ly6C, Gr1) low-expressing, monocyte-derived cells. We investigated molecular pathways balancing proinflammatory and restorative macrophages during fibrosis regression as well as pharmacologically augmenting beneficial macrophage functionality in fibrosis resolution. Therefore, we employed a Spiegelmer-based inhibitor of the chemokine, C-C motif chemokine ligand 2 (CCL2; monocyte chemoattractant protein 1), termed mNOX-E36, in the regression phase of two murine models of toxic (CCl4 ) and metabolic (methionine-choline-deficient diet) liver fibrosis. Although inflammation rapidly declined after cessation of injury, we observed a transient influx of Ly-6C(+) infiltrating monocytes (iMΦ), which are characterized by typical macrophage morphology, up-regulated expression of CCR2, and the pro-inflammatory cytokine, tumor necrosis factor (TNF), in injured liver. By inhibiting the early influx of Ly-6C(+) iMΦ by the CCL2 inhibitor, mNOX-E36, the intrahepatic macrophage equilibration shifted toward the "restorative" Ly-6C(-) subset of iMΦ. Consequently, fibrosis resolution was significantly accelerated upon mNOX-E36 administration in both models. Blocking transient recruitment of infiltrating Ly-6C(+) monocytes, but not direct effects of the inhibitor on the remaining macrophages, resulted in reduced intrahepatic levels of proinflammatory cytokines., Conclusion: Transient CCL2-dependent recruitment of infiltrating Ly-6C(+) monocytes during fibrosis regression counteracts scar resolution by perpetuating inflammatory reactions through release of proinflammatory cytokines such as TNF. Pharmacological inhibition of Ly-6C(+) monocyte recruitment using the CCL2-inhibitor, mNOX-E36, accelerates regression from toxic and metabolic liver fibrosis in two independent experimental models., (© 2014 by the American Association for the Study of Liver Diseases.)

Unlabelled: Interleukin (IL)-17 is a proinflammatory and fibrogenic cytokine mainly produced by T-helper (Th)17 lymphocytes, together with the hepatoprotective and antifibrogenic cytokine, IL-22. Cannabinoid receptor 2 (CB2) is predominantly expressed in immune cells and displays anti-inflammatory and antifibrogenic effects. In the present study, we further investigated the mechanism underlying antifibrogenic properties of CB2 receptor and explored its effect on the profibrogenic properties of IL-17. After bile duct ligation (BDL), the hepatic expression of Th17 markers and IL-17 production were enhanced in CB2(-/-) mice, as compared to wild-type (WT) counterparts, and correlated with increased fibrosis in these animals. In contrast, IL-22-induced expression was similar in both animal groups. Inhibition of Th17 differentiation by digoxin lowered Th17 marker gene expression and IL-17 production and strongly reduced liver fibrosis in CB2(-/-) BDL mice. In vitro, differentiation of CD4(+) naïve T cells into Th17 lymphocytes was decreased by the CB2 agonist, JWH-133, and was associated with reduced Th17 marker messenger RNA expression and IL-17 production, without modification of IL-22 release. The inhibitory effect of JWH-133 on IL-17 production relied on signal transducer and activator of transcription (STAT)5 phosphorylation. Indeed, STAT5 phosphorylation and translocation into the nucleus was enhanced in JWH133-treated Th17 lymphocytes, and the addition of a STAT5 inhibitor reversed the inhibitory effect of the CB2 agonist on IL-17 production, without affecting IL-22 levels. Finally, in vitro studies also demonstrated that CB2 receptor activation in macrophages and hepatic myofibroblasts blunts IL-17-induced proinflammatory gene expression., Conclusion: These data demonstrate that CB2 receptor activation decreases liver fibrosis by selectively reducing IL-17 production by Th17 lymphocytes via a STAT5-dependent pathway, and by blunting the proinflammatory effects of IL-17 on its target cells, while preserving IL-22 production., (© 2013 by the American Association for the Study of Liver Diseases.)

Unlabelled: Autoimmune hepatitis (AIH) can lead to cirrhosis, hepatic failure, and death. We aimed to identify predictors of advanced liver fibrosis at presentation, predictors of incomplete response to initial immunosuppression, and predictors of poor liver-related outcomes in the population-based AIH cohort from Canterbury, New Zealand. Cases diagnosed after 1980 that fulfilled standard diagnostic criteria were included. Cases were censored at death or liver transplantation and had a median follow-up of 9 years. Analyses were performed with Cox proportional hazards regression and logistic binary regression. The times to event outcomes were summarized using Kaplan-Meier curves. A total of 133 AIH patients were included. Predictors for advanced liver fibrosis at diagnosis were age at presentation of ≤20 years or >60 years (P = 0.02), serum albumin <36 g/L (P < 0.01), platelet <150 U/L (P < 0.01), and International Normalized Ratio (INR) >1.2 (P < 0.01). The only independent predictor for incomplete normalization of alanine aminotransferase (ALT) at 6 months was age at presentation ≤20 years. Independent predictors of poor liver-related outcomes were incomplete normalization of ALT at 6 months (P < 0.01), serum albumin <36 g/L (P < 0.01), and age at presentation of ≤20 years or >60 years (P = 0.01). Kaplan-Meier estimates showed that 10-year adverse liver event-free survival was 80% for age at presentation ≤20 years and >60 years, and 93% and 100% for age at presentation between 21-40 years and 41-60 years, respectively., Conclusion: Incomplete normalization of ALT at 6 months, low serum albumin concentration at diagnosis, and age at presentation of ≤20 years or >60 years were significant independent predictors of liver-related death or requirement for liver transplantation. Histological cirrhosis at diagnosis was not associated with poor prognosis and did not influence the response to initial immunosuppressive treatment. (HEPATOLOGY 2013;57:2399-2406)., (Copyright © 2013 American Association for the Study of Liver Diseases.)

Unlabelled: Liver fibrosis is a wound healing response to chronic liver injury and inflammation in which macrophages and infiltrating monocytes participate in both the development and resolution phase. In humans, three monocyte subsets have been identified: the classical CD14++CD16-, intermediate CD14++CD16+, and nonclassical CD14+CD16++ monocytes. We studied the phenotype and function of these monocyte subsets in peripheral blood and liver tissue from patients with chronic inflammatory and fibrotic liver diseases. The frequency of intrahepatic monocytes increased in disease compared with control liver tissue, and in both nondiseased and diseased livers there was a higher frequency of CD14++CD16+ cells with blood. Our data suggest two nonexclusive mechanisms of CD14++CD16+ accumulation in the inflamed liver: (1) recruitment from blood, because more than twice as many CD14++CD16+ monocytes underwent transendothelial migration through hepatic endothelial cells compared with CD14++CD16- cells; and (2) local differentiation from CD14++CD16- classical monocytes in response to transforming growth factor β and interleukin (IL)-10. Intrahepatic CD14++CD16+ cells expressed both macrophage and dendritic cell markers but showed high levels of phagocytic activity, antigen presentation, and T cell proliferation and secreted proinflammatory (tumor necrosis factor α, IL-6, IL-8, IL-1β) and profibrogenic cytokines (IL-13), chemokines (CCL1, CCL2, CCL3, CCL5), and growth factors (granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor), consistent with a role in the wound healing response., Conclusion: Intermediate CD14++CD16+ monocytes preferentially accumulate in chronically inflamed human liver as a consequence of enhanced recruitment from blood and local differentiation from classical CD14++CD16- monocytes. Their phagocytic potential and ability to secrete inflammatory and profibrogenic cytokines suggests they play an important role in hepatic fibrogenesis., (Copyright © 2012 American Association for the Study of Liver Diseases.)

Unlabelled: Hepatitis C virus (HCV)-specific immune effector responses can cause liver damage in chronic infection. Hepatic stellate cells (HSC) are the main effectors of liver fibrosis. TGFβ, produced by HCV-specific CD8(+) T cells, is a key regulatory cytokine modulating HCV-specific effector T cells. Here we studied TGFβ as well as other factors produced by HCV-specific intrahepatic lymphocytes (IHL) and peripheral blood cells in hepatic inflammation and fibrogenesis. This was a cross-sectional study of two well-defined groups of HCV-infected subjects with slow (≤ 0.1 Metavir units/year, n = 13) or rapid (n = 6) liver fibrosis progression. HCV-specific T-cell responses were studied using interferon-gamma (IFNγ)-ELISpot ±monoclonal antibodies (mAbs) blocking regulatory cytokines, along with multiplex, enzyme-linked immunosorbent assay (ELISA) and multiparameter fluorescence-activated cell sorting (FACS). The effects of IHL stimulated with HCV-core peptides on HSC expression of profibrotic and fibrolytic genes were determined. Blocking regulatory cytokines significantly raised detection of HCV-specific effector (IFNγ) responses only in slow fibrosis progressors, both in the periphery (P = 0.003) and liver (P = 0.01). Regulatory cytokine blockade revealed HCV-specific IFNγ responses strongly correlated with HCV-specific TGFβ, measured before blockade (R = 0.84, P = 0.0003), with only a trend to correlation with HCV-specific IL-10. HCV-specific TGFβ was produced by CD8 and CD4 T cells. HCV-specific TGFβ, not interleukin (IL)-10, inversely correlated with liver inflammation (R = -0.63, P = 0.008) and, unexpectedly, fibrosis (R = -0.46, P = 0.05). In addition, supernatants from HCV-stimulated IHL of slow progressors specifically increased fibrolytic gene expression in HSC and treatment with anti-TGFβ mAb abrogated such expression., Conclusion: Although TGFβ is considered a major profibrogenic cytokine, local production of TGFβ by HCV-specific T cells appeared to have a protective role in HCV-infected liver, together with other T-cell-derived factors, ameliorating HCV liver disease progression., (Copyright © 2012 American Association for the Study of Liver Diseases.)

Unlabelled: Clinical trials and animal models suggest that infusion of bone marrow cells (BMCs) is effective therapy for liver fibrosis, but the underlying mechanisms are obscure, especially those associated with early effects of BMCs. Here, we analyzed the early impact of BMC infusion and identified the subsets of BMCs showing antifibrotic effects in mice with carbon tetrachloride-induced liver fibrosis. An interaction between BMCs and activated hepatic stellate cells (HSCs) was investigated using an in vitro coculturing system. Within 24 hours, infused BMCs were in close contact with activated HSCs, which was associated with reduced liver fibrosis, enhanced hepatic expression of interleukin (IL)-10, and expanded regulatory T cells but decreased macrophage infiltration in the liver at 24 hours after BMC infusion. In contrast, IL-10-deficient (IL-10(-/-) ) BMCs failed to reproduce these effects in fibrotic livers. Intriguingly, in isolated cells, CD11b(+) Gr1(high) F4/80(-) and CD11b(+) Gr1(+) F4/80(+) BMCs expressed more IL-10 after coculturing with activated HSCs, leading to suppressed expression of collagen and α-smooth muscle actin in HSCs. Moreover, these effects were either enhanced or abrogated, respectively, when BMCs were cocultured with IL-6(-/-) and retinaldehyde dehydrogenase 1(-/-) HSCs. Similar to murine data, human BMCs expressed more IL-10 after coculturing with human HSC lines (LX-2 or hTERT), and serum IL-10 levels were significantly elevated in patients with liver cirrhosis after autologous BMC infusion., Conclusion: Activated HSCs increase IL-10 expression in BMCs (CD11b(+) Gr1(high) F4/80(-) and CD11b(+) Gr1(+) F4/80(+) cells), which in turn ameliorates liver fibrosis. Our findings could enhance the design of BMC therapy for liver fibrosis., (Copyright © 2012 American Association for the Study of Liver Diseases.)

Unlabelled: Cirrhosis with ascites is associated with a high rate of gut bacterial translocation (GBT) and spontaneous bacterial infections of enteric origin. We addressed the activation state and role of intestinal dendritic cells (DCs) in experimental ascitic cirrhosis and their relationship with GBT. Cirrhosis with ascites was CCl(4) induced in rats. To examine their activation state and functions, DCs (CD103(+) RT1B(+) CD3(-) CD45RA(-) ) were isolated from the intestinal lamina propria and mesenteric lymph nodes (MLNs), and the following parameters were determined by flow cytometry: surface antigen expression; spontaneous or lipopolysaccharide-stimulated tumor necrosis factor alpha (TNF-α) production; and in vitro capacity to phagocytose latex beads and to migrate toward the chemokine (C-C motif) ligand 21. GBT was defined as the growth of bacteria in MLNs culture. Bacterial DNA (Bact-DNA) in MLNs was identified by polymerase chain reaction. In rats with Bact-DNA in MLNs without GBT, intestinal and MLNs CD103(+) -DCs showed features of activation, expansion of the proinflammatory CD4(+) -DC subpopulation, augmented TNF-α production, and increased phagocytic and migratory capacities. In contrast, in rats with GBT, CD103(+) -DCs showed the absence of an activated phenotype, lowered TNF-α production, and relatively deficient phagocytosis and migration capacities. The CD103(+) -DC of rats without Bact-DNA in MLNs or GBT were similar to controls. In cirrhotic rats, bowel decontamination with antibiotics eliminated Bact-DNA in MLNs and GBT, normalized the activation state and functions of CD103(+) -DCs, and increased their TNF-α production., Conclusion: In experimental cirrhosis with ascites, continuous pressure of gut bacteria shapes the phenotypic and functional profile of intestinal DCs to produce effects that range from their activation and enhanced functions to their exhaustion and tolerance., (Copyright © 2012 American Association for the Study of Liver Diseases.)

Unlabelled: Natural killer (NK) cells play a role in the early control and natural course of hepatitis C virus (HCV) infection. NK cell function is regulated by a multitude of receptors, including activating NKp46 receptor. However, reports on NKp46 in hepatitis C are controversial. Therefore, we investigated the hepatic recruitment and function of NKp46(+) NK cells, considering differential surface expression of NKp46 resulting in NKp46(High) and NKp46(Dim) subsets. Intra- and extrahepatic NK-cell subsets from HCV-infected patients were characterized by flow cytometry. Cytotoxic activity and interferon-gamma (IFN-γ) secretion were studied using K-562, P815, and primary hepatic stellate cells as targets. Anti-HCV activity of NK-cell subsets was studied using the replicon system. Density of NKp46 surface expression clearly segregated NKp46(Dim) and NKp46(High) subsets, which differed significantly with respect to the coexpression of maturation markers and NK-cell receptors. More important, NKp46(High) NK cells showed a higher cytolytic activity and stronger IFN-γ secretion than NKp46(Dim) NK cells. Accordingly, NKp46(High) NK cells efficiently blocked HCV replication in vitro. Blocking experiments confirmed an important role for the NKp46 receptor. Furthermore, we found an intrahepatic accumulation of NKp46(High) NK cells. Of note, high cytolytic activity of NKp46(High) NK cells was also confirmed in the intrahepatic NK-cell population, and the frequency of intrahepatic NKp46(High) NK cells was inversely correlated with HCV-RNA levels and fibrosis stage., Conclusions: NKp46(High) expression defines a specific NK-cell subset that may be involved in both the suppression of HCV replication and HCV-associated liver damage underpinning the role of NK cells in the immunopathogenesis of HCV., (Copyright © 2012 American Association for the Study of Liver Diseases.)

Sustained hepatic inflammation, driven by alcohol consumption, nonalcoholic fatty liver disease, and/or chronic viral hepatitis (hepatitis B and C), results in damage to parenchyma, oxidative stress, and compensatory regeneration/proliferation. There is substantial evidence linking these inflammation-associated events with the increased incidence of hepatocellular carcinogenesis. Although acute liver inflammation can play a vital and beneficial role in response to liver damage or acute infection, the effects of chronic liver inflammation, including liver fibrosis and cirrhosis, are sufficient in a fraction of individuals to initiate the process of transformation and the development of hepatocellular carcinoma. This review highlights immune-dependent mechanisms that may be associated with hepatocellular oncogenesis, including critical transformative events/pathways in the context of chronic inflammation and subverted tolerogenesis., (Copyright © 2012 American Association for the Study of Liver Diseases.)

Unlabelled: Interleukin (IL)-22 is known to play a key role in promoting antimicrobial immunity, inflammation, and tissue repair at barrier surfaces by binding to the receptors, IL-10R2 and IL-22R1. IL-22R1 is generally thought to be expressed exclusively in epithelial cells. In this study, we identified high levels of IL-10R2 and IL-22R1 expression on hepatic stellate cells (HSCs), the predominant cell type involved in liver fibrogenesis in response to liver damage. In vitro treatment with IL-22 induced the activation of signal transducer and activator of transcription (STAT) 3 in primary mouse and human HSCs. IL-22 administration prevented HSC apoptosis in vitro and in vivo, but surprisingly, the overexpression of IL-22 by either gene targeting (e.g., IL-22 transgenic mice) or exogenous administration of adenovirus expressing IL-22 reduced liver fibrosis and accelerated the resolution of liver fibrosis during recovery. Furthermore, IL-22 overexpression or treatment increased the number of senescence-associated beta-galactosidase-positive HSCs and decreased alpha-smooth muscle actin expression in fibrotic livers in vivo and cultured HSCs in vitro. Deletion of STAT3 prevented IL-22-induced HSC senescence in vitro, whereas the overexpression of a constitutively activated form of STAT3 promoted HSC senescence through p53- and p21-dependent pathways. Finally, IL-22 treatment up-regulated the suppressor of cytokine signaling (SOCS) 3 expression in HSCs. Immunoprecipitation analyses revealed that SOCS3 bound p53 and subsequently increased the expression of p53 and its target genes, contributing to IL-22-mediated HSC senescence., Conclusion: IL-22 induces the senescence of HSCs, which express both IL-10R2 and IL-22R1, thereby ameliorating liver fibrogenesis. The antifibrotic effect of IL-22 is likely mediated by the induction of HSC senescence, in addition to the previously discovered hepatoprotective functions of IL-22., (Copyright © 2012 American Association for the Study of Liver Diseases.)

Unlabelled: Liver damage in humans is induced by various insults including alcohol abuse, hepatitis B/C virus infection, autoimmune or metabolic disorders and, when persistent, leads to development of liver fibrosis. Because the nuclear factor-κB (NF-κB) system is activated in response to several of these stresses, we hypothesized that NF-κB activation in hepatocytes may contribute to fibrosis development. To activate the NF-κB signaling pathway in a time- and cell-type-specific manner in the liver, we crossed transgenic mice carrying the tetracycline-responsive transactivator under the control of the liver activator protein promotor with transgenic mice carrying a constitutively active form of the Ikbkb gene (IKK2 protein [CAIKK2]). Double-transgenic mice displayed doxycycline-regulated CAIKK2 expression in hepatocytes. Removal of doxycycline at birth led to activation of NF-κB signaling, moderate liver damage, recruitment of inflammatory cells, hepatocyte proliferation, and ultimately to spontaneous liver fibrosis development. Microarray analysis revealed prominent up-regulation of chemokines and chemokine receptors and this induction was rapidly reversed after switching off the CAIKK2 expression. Turning off the transgene expression for 3 weeks reversed stellate cell activation but did not diminish liver fibrosis. The elimination of macrophages by clodronate-liposomes attenuated NF-κB-induced liver fibrosis in a liver-injury-independent manner., Conclusion: Our results revealed that hepatic activation of IKK/NF-κB is sufficient to induce liver fibrosis by way of macrophage-mediated chronic inflammation. Therefore, agents controlling the hepatic NF-κB system represent attractive therapeutic tools to prevent fibrosis development in multiple chronic liver diseases., (Copyright © 2012 American Association for the Study of Liver Diseases.)

Hepatocellular carcinoma (HCC) is a rising worldwide cause of cancer mortality, making the elucidation of its underlying mechanisms an urgent priority. The liver is unique in its response to injury, simultaneously undergoing regeneration and fibrosis. HCC occurs in the context of these two divergent responses, leading to distinctive pathways of carcinogenesis. In this review we highlight pathways of liver tumorigenesis that depend on, or are enhanced by, fibrosis. Activated hepatic stellate cells drive fibrogenesis, changing the composition of the extracellular matrix. Matrix quantity and stiffness also increase, providing a reservoir for bound growth factors. In addition to promoting angiogenesis, these factors may enhance the survival of both preneoplastic hepatocytes and activated hepatic stellate cells. Fibrotic changes also modulate the activity of inflammatory cells in the liver, reducing the activity of natural killer and natural killer T cells that normally contribute to tumor surveillance. These pathways synergize with inflammatory signals, including telomerase reactivation and reactive oxygen species release, ultimately resulting in cancer. Clarifying fibrosis-dependent tumorigenic mechanisms will help rationalize antifibrotic therapies as a strategy to prevent and treat HCC., (Copyright © 2012 American Association for the Study of Liver Diseases.)

Unlabelled: Elucidation of the molecular events underlying hepatic stellate cell (HSC) activation is an essential step toward understanding the biological properties of HSC and clarifying the potential roles of HSCs in liver fibrosis and other liver diseases, including hepatocellular carcinoma. High-throughput comparative proteomic analysis based on isobaric tags for relative and absolute quantitation (iTRAQ) labeling combined with online two-dimensional nanoscale liquid chromatography and tandem mass spectrometry (2D nano-LC-MS/MS) were performed on an in vitro HSC activation model to obtain a comprehensive view of the protein ensembles associated with HSC activation. In total, 2,417 proteins were confidently identified (false discovery rate <1%), of which 2,322 proteins were quantified. Compared with quiescent HSCs, 519 proteins showed significant differences in activated HSCs (≥ 3.0-fold). Bioinformatics analyses using Ingenuity Pathway Analysis revealed that the 319 up-regulated proteins represented multiple cellular functions closely associated with HSC activation, such as extracellular matrix synthesis and proliferation. In addition to the well-known markers for HSC activation, such as α-smooth muscle actin and collagen types 1 and 3, some novel proteins potentially associated with HSC activation were identified, while the 200 down-regulated proteins were primarily related to immune response and lipid metabolism. Most intriguingly, the top biological function, top network, and top canonical pathway of down-regulated proteins were all involved in immune responses. The expression and/or biological function of a set of proteins were properly validated, especially Bcl2-associated athanogene 2, BAG3, and B7H3., Conclusion: The present study provided the most comprehensive proteome profile of rat HSCs and some novel insights into HSC activation, especially the suppressed immune response., (Copyright © 2012 American Association for the Study of Liver Diseases.)

Unlabelled: Induction or overexpression of the heme-degrading enzyme, heme oxygenase 1 (HO-1), has been shown to protect mice from liver damage induced by acute inflammation. We have investigated the effects of HO-1 induction in a mouse model of chronic liver inflammation and fibrogenesis with progression to hepatocellular carcinoma (HCC) (Mdr2ko; FVB.129P2-Abcb4(tm1Bor)). HO-1 was induced in vivo by treatment with cobalt protoporphyrin IX, starting at week 5 or 12 of mice lifespan, and continued for 7 weeks. Our results showed that HO-1 induction reduced liver damage and chronic inflammation by regulating immune cell infiltration or proliferation as well as tumor necrosis factor receptor signaling. Fibrosis progression was significantly reduced by HO-1 induction in mice with mild, as well as established, portal and lobular fibrosis. HO-1 induction significantly suppressed hepatic stellate cell activation. During established fibrosis, HO-1 induction was able to revert portal inflammation and fibrosis below levels observed at the start of treatment. Moreover, hepatocellular proliferation and signs of dysplasia were decreased after HO-1 induction., Conclusion: Induction of HO-1 interferes with chronic inflammation and fibrogenesis and, in consequence, might delay progression to HCC., (Copyright © 2011 American Association for the Study of Liver Diseases.)

Unlabelled: Although hepatic fibrosis typically follows chronic inflammation, fibrosis will often regress after cessation of liver injury. In this study, we examined whether liver dendritic cells (DCs) play a role in liver fibrosis regression using carbon tetrachloride to induce liver injury. We examined DC dynamics during fibrosis regression and their capacity to modulate liver fibrosis regression upon cessation of injury. We show that conditional DC depletion soon after discontinuation of the liver insult leads to delayed fibrosis regression and reduced clearance of activated hepatic stellate cells, the key fibrogenic cell in the liver. Conversely, DC expansion induced either by Flt3L (fms-like tyrosine kinase-3 ligand) or adoptive transfer of purified DCs accelerates liver fibrosis regression. DC modulation of fibrosis was partially dependent on matrix metalloproteinase (MMP)-9, because MMP-9 inhibition abolished the Flt3L-mediated effect and the ability of transferred DCs to accelerate fibrosis regression. In contrast, transfer of DCs from MMP-9-deficient mice failed to improve fibrosis regression., Conclusion: Taken together, these results suggest that DCs increase fibrosis regression and that the effect is correlated with their production of MMP-9. The results also suggest that Flt3L treatment during fibrosis resolution merits evaluation to accelerate regression of advanced liver fibrosis., (Copyright © 2011 American Association for the Study of Liver Diseases.)

Unlabelled: Activation of innate immunity (natural killer [NK] cell/interferon-γ [IFN-γ]) has been shown to play an important role in antiviral and antitumor defenses as well as antifibrogenesis. However, little is known about the regulation of innate immunity during chronic liver injury. Here, we compared the functions of NK cells in early and advanced liver fibrosis induced by a 2-week or a 10-week carbon tetrachloride (CCl(4) ) challenge, respectively. Injection of polyinosinic-polycytidylic acid (poly I:C) or IFN-γ induced NK cell activation and NK cell killing of hepatic stellate cells (HSCs) in the 2-week CCl(4) model. Such activation was diminished in the 10-week CCl(4) model. Consistent with these findings, the inhibitory effect of poly I:C and IFN-γ on liver fibrosis was markedly reduced in the 10-week versus the 2-week CCl(4) model. In vitro coculture experiments demonstrated that 4-day cultured (early activated) HSCs induce NK cell activation via an NK group 2 member D/retinoic acid-induced early gene 1-dependent mechanism. Such activation was reduced when cocultured with 8-day cultured (intermediately activated) HSCs due to the production of transforming growth factor-β (TGF-β) by HSCs. Moreover, early activated HSCs were sensitive, whereas intermediately activated HSCs were resistant to IFN-γ-mediated inhibition of cell proliferation, likely due to elevated expression of suppressor of cytokine signaling 1 (SOCS1). Disruption of the SOCS1 gene restored the IFN-γ inhibition of cell proliferation in intermediately activated HSCs. Production of retinol metabolites by HSCs contributed to SOCS1 induction and subsequently inhibited IFN-γ signaling and functioning, whereas production of TGF-β by HSCs inhibited NK cell function and cytotoxicity against HSCs., Conclusion: The antifibrogenic effects of NK cell/IFN-γ are suppressed during advanced liver injury, which is likely due to increased production of TGF-β and expression of SOCS1 in intermediately activated HSCs., (2011 American Association for the Study of Liver Diseases.)

Unlabelled: Murine models of autoimmunity allow the study of the earliest events in disease pathogenesis. Our laboratory has developed a xenobiotic induced model of primary biliary cirrhosis (PBC) following immunization of mice with 2-octynoic acid coupled to bovine serum albumin (2-OA-BSA), an antigen selected following quantitative structure-activity relationship analysis of the E2 subunit of the pyruvate dehydrogenase complex (PDC-E2), the immunodominant autoantigen of PBC. Recent data in humans with PBC has suggested that a major component of liver pathology is due to activation of innate immunity. We took advantage of our 2-OA-BSA model and immunized mice with and without the addition of α-galactosylceramide (α-GalCer), an invariant natural killer T cell activator. Importantly, we report herein that 2-OA-BSA-immunized mice exposed to α-GalCer develop a profound exacerbation of their autoimmune cholangitis, including significant increases in CD8(+) T-cell infiltrates, portal inflammation, granuloma formation, and bile duct damage. Furthermore, such mice produce increased levels of antimitochondrial antibodies and have evidence of fibrosis, a feature not previously reported in the murine models of PBC., Conclusion: Our data suggests a primary role of innate immunity in the exacerbation of autoimmune cholangitis and also become a logical explanation for the recurrence of PBC following liver transplantation in the absence of major histocompatability complex compatibility. We submit that PBC begins with loss of tolerance to PDC-E2 and a multilineage antimitochondrial response in which autoreactive CD8(+) T cells are critical. However, the perpetuation of disease and its exacerbation will also be modulated by innate immune mechanisms., (Copyright © 2010 American Association for the Study of Liver Diseases.)

Unlabelled: An imbalance of plasma amino acids is observed in patients with advanced cirrhosis. The aim of this study was to investigate the influence of the extracellular amino acid imbalance on the function of myeloid dendritic cells (DCs) in patients with advanced cirrhosis. We made a serum-free culture medium consistent with the average concentration of plasma amino acids from healthy controls (HC, n = 25) or patients with advanced cirrhosis (LC, n = 43) to reflect more closely the actual environment of the living body. We compared the phenotypical and biological functions of blood dendritic cells antigen-positive dendritic cells (BDCA+ DCs) and monocyte-derived dendritic cells (MoDCs) from LC and HC with these media. After adding stimulants, the CD83 and CD86 expressions of DCs from LC were lower than those from HC. In both HC and LC, both CD83 and CD86 expressions of DCs stimulated under the cirrhotic medium were lower than under the control medium. This phenomenon was accompanied by a suppression of the mammalian target of rapamycin (mTOR)/S6K-signaling pathways. The interleukin 12 (IL-12) production in the cirrhotic medium was significantly lower than in the control medium and increased when valine or leucine was added to the medium. In patients with advanced cirrhosis, peripheral blood mononuclear cells stimulated in the autologous plasma after oral administration of branched-chain amino acid (BCAA) granules had significantly increased interferon gamma production., Conclusion: In advanced cirrhosis, there is impairment of the function and maturation of DCs, which has been shown to be related to an imbalance in the extracellular amino acid profile. Elevating the extracellular concentration of BCAAs ex vivo in patients with advanced cirrhosis improved the function of DCs.

Unlabelled: In addition to liver-resident Kupffer cells, infiltrating immune cells have recently been linked to the development of liver fibrosis. Blood monocytes are circulating precursors of tissue macrophages and can be divided into two functionally distinct subpopulations in mice: Gr1(hi) (Ly6C(hi)) and Gr1(lo) (Ly6C(lo)) monocytes. The role of these monocyte subsets in hepatic fibrosis and the mechanisms of their differential recruitment into the injured liver are unknown. We therefore characterized subpopulations of infiltrating monocytes in acute and chronic carbon tetrachloride (CCl(4))-induced liver injury in mice using flow cytometry and immunohistochemistry. Inflammatory Gr1(hi) but not Gr1(lo) monocytes are massively recruited into the liver upon toxic injury constituting an up to 10-fold increase in CD11b(+)F4/80(+) intrahepatic macrophages. Comparing wild-type with C-C chemokine receptor (CCR2)-deficient and CCR2/CCR6-deficient mice revealed that CCR2 critically controls intrahepatic Gr1(hi) monocyte accumulation by mediating their egress from bone marrow. During chronic liver damage, intrahepatic CD11b(+)F4/80(+)Gr1(+) monocyte-derived cells differentiate preferentially into inducible nitric oxide synthase-producing macrophages exerting proinflammatory and profibrogenic actions, such as promoting hepatic stellate cell (HSC) activation, T helper 1-T cell differentiation and transforming growth factor beta (TGF-beta) release. Impaired monocyte subset recruitment in Ccr2(-/-) and Ccr2(-/-)Ccr6(-/-) mice results in reduced HSC activation and diminished liver fibrosis. Moreover, adoptively transferred Gr1(hi) monocytes traffic into the injured liver and promote fibrosis progression in wild-type and Ccr2(-/-)Ccr6(-/-) mice, which are otherwise protected from hepatic fibrosis. Intrahepatic CD11b(+)F4/80(+)Gr1(+) monocyte-derived macrophages purified from CCl(4)-treated animals, but not naïve bone marrow monocytes or control lymphocytes, directly activate HSCs in a TGF-beta-dependent manner in vitro., Conclusion: Inflammatory Gr1(+) monocytes, recruited into the injured liver via CCR2-dependent bone marrow egress, promote the progression of liver fibrosis. Thus, they may represent an interesting novel target for antifibrotic strategies.

Unlabelled: Liver fibrosis is a common scarring response to all forms of chronic liver injury and is always associated with inflammation that contributes to fibrogenesis. Although a variety of cell populations infiltrate the liver during inflammation, it is generically clear that CD8 T lymphocytes promote while natural killer (NK) cells inhibit liver fibrosis. However, the role of invariant natural killer T (iNKT) cells, which are abundant in the liver, in hepatic fibrogenesis, remains obscure. Here we show that iNKT-deficient mice are more susceptible to carbon tetrachloride (CCl(4))-induced acute liver injury and inflammation. The protective effect of naturally activated iNKT in this model is likely mediated via suppression of the proinflammatory effect of activated hepatic stellate cells. Interestingly, strong activation of iNKT through injection of iNKT activator alpha-galactosylceramide (alpha-GalCer) accelerates CCl(4)-induced acute liver injury and fibrosis. In contrast, chronic CCl(4) administration induces a similar degree of liver injury in iNKT-deficient and wild-type mice, and only a slightly higher grade of liver fibrosis in iNKT-deficient mice than wild-type mice 2 weeks but not 4 weeks after CCl(4) injection, although iNKT cells are able to kill activated stellate cells. An insignificant role of iNKT in chronic liver injury and fibrosis may be attributable to hepatic iNKT cell depletion. Finally, chronic alpha-GalCer treatment had little effect on liver injury and fibrosis, which is attributable to iNKT tolerance after alpha-GalCer injection., Conclusion: Natural activation of hepatic iNKT cells inhibits, whereas strong activation of iNKT cells by alpha-GalCer accelerates CCl(4)-induced acute liver injury, inflammation, and fibrosis. During chronic liver injury, hepatic iNKT cells are depleted and play a role in inhibiting liver fibrosis in the early stage but not the late stage of fibrosis.

Unlabelled: Bacterial infections and severity of associated inflammatory reaction influence prognosis in patients with advanced cirrhosis. We compared the innate immune response to bacterial DNA (bactDNA) translocation with that caused by viable bacteria translocation in patients with spontaneous bacterial peritonitis and the relationship between the cytokine response and serum levels of bactDNA. The bactDNA translocation was investigated in 226 patients with cirrhosis and noninfected ascites, 22 patients with spontaneous bacterial peritonitis, and 10 patients with ascites receiving continuous norfloxacin. Serum and ascitic fluid tumor necrosis factor alpha, interferon-gamma, interleukin-12, and nitric oxide metabolites were measured via enzyme-linked immunosorbent assay. Bacterial genomic identifications were made via amplification and sequencing of the 16S ribosomal RNA gene and digital quantization with DNA Lab-on-chips. The bactDNA was present in 77 noninfected patients (34%) and in all cases of spontaneous bacterial peritonitis, even in those with culture-negative ascitic fluid. No patient receiving norfloxacin showed bactDNA translocation. Levels of all cytokines were similar in patients with bactDNA translocation or spontaneous bacterial peritonitis and significantly higher than in patients without bactDNA or in those receiving norfloxacin. Serum bactDNA concentration paralleled levels of all cytokines and nitric oxide in a series of patients with bactDNA translocation or spontaneous bacterial peritonitis followed during 72 hours. Antibiotic treatment in the series of patients with spontaneous bacterial peritonitis did not abrogate bactDNA translocation in the short term., Conclusion: bactDNA translocation-associated cytokine response is indistinguishable from that in patients with spontaneous bacterial peritonitis and is dependent on bactDNA concentration. Norfloxacin abrogates bactDNA translocation and cytokine response.