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Alcoholic liver disease (ALD) has been among the leading causes of cirrhosis and liver-related death worldwide for decades. Early discoveries in alcoholic liver disease identified increased levels of bacterial endotoxin in the portal circulation, suggesting a role for gut-derived toxins in ALD. Indeed, alcohol consumption can disrupt the intestinal epithelial barrier and result in increased gut permeability that increasingly is recognized as a major factor in ALD. Bacterial endotoxin, lipopolysaccharide, is a prototypic microbe-derived inflammatory signal that contributes to inflammation in ALD through activation of the Toll-like receptor 4. Recent studies also have shown that alcohol consumption is associated with alterations in the gut microbiome, and the dysbalance of pathogenic and commensal organisms in the intestinal microbiome may contribute to the abnormal gut–liver axis in ALD. Indeed, bacterial decontamination improves ALD both in human and animal models. This short review summarizes recent findings and highlights emerging trends in the gut–liver axis relevant to ALD. [ABSTRACT FROM AUTHOR]

Background & Aims: Dendritic cells (DCs) initiate and sustain an efficient T-lymphocyte response. Chronic hepatitis C virus (HCV) infection is associated with inefficient T-cell functions that fail to eradicate the virus, so defects in DC function might be involved in HCV pathogenesis. This study analyzed the activities of myeloid DCs and distinct CD4+ T-cell populations in samples collected from patients with HCV. Methods: The abilities of primary BDCA1+ or monocyte-derived DCs from HCV patients (HCV-DC) to stimulate CD4+, CD4+CD25−, or different ratios of CD4+CD25+/CD4+CD25− T cells were evaluated in mixed lymphocyte reactions. T-cell proliferation and phenotype were evaluated by flow cytometry; cytokine production was evaluated by enzyme-linked immunosorbent assay and marker expression by polymerase chain reaction analyses. Results: HCV-DCs were poor activators of CD4+ T cells; this defect was reversed by addition of interleukin-2, neutralization of interleukin-10, or elimination of CD4+CD25+ T cells. HCV-DC stimulated proliferation of regulatory T cells (Tregs; CD4+CD25+FoxP3+), which limit proliferation of HCV-specific T lymphocytes. We observed an increased frequency of CD4+CD25+ T cells in peripheral blood of HCV patients and that HCV-DC overexpressed a number of alternative costimulatory molecules, including PD-L1. Finally, HCV-DC stimulated expansion rather than de novo induction of FoxP3+ Tregs. Conclusions: Our results indicate a role for myeloid DC in expansion of Tregs to promote chronic infection of patients with HCV. [Copyright &y& Elsevier]

Background & Aims: Persistent inflammation contributes to progression of liver damage in chronic HCV (cHCV) infection. Repeated exposure to toll-like receptor (TLR) ligands results in tolerance, a protective mechanism aimed at limiting inflammation. Methods: Monocytes/macrophages were repeatedly stimulated via proinflammatory cytokine-inducing TLRs and evaluated for activation markers. Results: Unlike monocytes of controls or patients with nonalcoholic steatohepatitis, the monocytes of cHCV patients were hyperresponsive and failed to show homo- or heterotolerance to TLR ligands, manifested by elevated tumor necrosis factor (TNF)-α production. Serum levels of interferon (IFN)-γ, endotoxin (TLR4 ligand), and HCV core protein (TLR2 ligand) were elevated in cHCV patients suggesting potential mechanisms for in vivo monocyte preactivation. Treatment of normal monocytes with IFN-γ resulted in loss of tolerance to lipopolysaccharide (LPS) or HCV core protein. Furthermore, we found increased levels of MyD88-IRAK1 complexes and nuclear factor (NF)-κB activity both in monocytes of cHCV patients and in normal monocytes that lost TLR tolerance after IFN-γ + LPS pretreatment. In vitro differentiation of TLR non-tolerant cHCV monocytes into macrophages restored their capacity to exhibit TLR tolerance to LPS and HCV core protein, and this could be reversed by administration of IFN-γ. cHCV patients exhibited increased TNF-α in the circulation and in the liver. In cHCV livers, we found Kupffer cell/macrophage activation indicated by increased CD163 and CD33 expression. Conclusions: We identified that host-derived factors (IFN-γ and endotoxin) and viral factors (HCV core protein) act in tandem to induce and maintain monocyte/macrophage activation, thus favoring persistent inflammation in patients with cHCV infection. [Copyright &y& Elsevier]

Background & Aims Chronic, excessive alcohol consumption leads to alcoholic liver disease (ALD) characterized by steatosis, inflammation, and eventually cirrhosis. The hepatocyte specific microRNA 122 (MIR122) regulates hepatocyte differentiation and metabolism. We investigated whether an alcohol-induced decrease in level of MIR122 contributes to development of ALD. Methods We obtained liver samples from 12 patients with ALD and cirrhosis and 9 healthy individuals (controls) and analyzed them by histology and immunohistochemistry. C57Bl/6 mice were placed on a Lieber-DeCarli liquid diet, in which they were fed ethanol for 8 weeks, as a model of ALD, or a control diet. These mice were also given injections of CCl4, to increase liver fibrosis, for 8 weeks. On day 28, mice with ethanol-induced liver disease and advanced fibrosis, and controls, were given injections of recombinant adeno-associated virus 8 vector that expressed the primary miR-122 transcript (pri-MIR122, to overexpress MIR122 in hepatocytes) or vector (control). Two weeks before ethanol feeding, some mice were given injections of a vector that expressed an anti-MIR122, to knock down its expression. Serum and liver tissues were collected; hepatocytes and liver mononuclear cells were analyzed by histology, immunoblots, and confocal microscopy. We performed in silico analyses to identify targets of MIR122 and chromatin immunoprecipitation quantitative polymerase chain reaction analyses in Huh-7 cells. Results Levels of MIR122 were decreased in liver samples from patients with ALD and mice on the Lieber-DeCarli diet, compared with controls. Transgenic expression of MIR122 in hepatocytes of mice with ethanol-induced liver disease and advanced fibrosis significantly reduced serum levels of alanine aminotransferase (ALT) and liver steatosis and fibrosis, compared with mice given injections of the control vector. Ethanol feeding reduced expression of pri-MIR122 by increasing expression of the spliced form of the transcription factor grainyhead like transcription factor 2 (GRHL2) in liver tissues from mice. Levels of GRHL2 also were increased in liver tissues from patients with ALD, compared with controls; increases correlated with decreases in levels of MIR122 in human liver. Mice given injections of the anti-MIR122 before ethanol feeding had increased steatosis, inflammation, and serum levels of alanine aminotransferase compared with mice given a control vector. Levels of hypoxia-inducible factor 1 alpha ( HIF1α ) mRNA, a target of MIR122, were increased in liver tissues from patients and mice with ALD, compared with controls. Mice with hepatocyte-specific disruption of Hif1α developed less-severe liver injury following administration of ethanol, injection of anti-MIR122, or both. Conclusions Levels of MIR122 decrease in livers from patients with ALD and mice with ethanol-induced liver disease, compared with controls. Transcription of MIR122 is inhibited by GRHL2, which is increased in livers of mice and patients with ALD. Expression of an anti-MIR122 worsened the severity of liver damage following ethanol feeding in mice. MIR122 appears to protect the liver from ethanol-induced damage by reducing levels of HIF1α. These processes might be manipulated to reduce the severity of ALD in patients. [ABSTRACT FROM AUTHOR]

Background & Aims: The type III interferons (IFN-λs: interleukin [IL]-28a, IL-28b, and IL-29) have important roles in hepatitis C virus (HCV) infection, but little is understood about what cells produce these cytokines or how production is activated. We investigated whether human immune cells recognize HCV-infected cells and respond by producing IFN-λ. Methods: We cultured healthy human peripheral blood mononuclear cells (PBMCs) with different populations of immune cells and Japanese fulminant hepatitis-1 (JFH-1) HCV-infected Huh7.5 (cell culture–derived HCV particles [HCVcc]/Huh7.5) cells. Results: Human PBMCs recognized HCVcc/Huh7.5 cells and responded by producing IFN-α, IFN-γ, and IFN-λ. A rare subset of myeloid dendritic cells (mDCs), which are blood DC antigen (BDCA)+ (also called mDC2 cells), were the major source of IL-28 and IL-29 production in response to HCVcc/Huh7.5 cells. Plasmacytoid DCs produced IFN-α, whereas natural killer and natural killer T cells were the main source of IFN-γ production in co-culture experiments. Of the endosomal Toll-like receptors (TLRs)3, 7, 8, and 9, only TLR3 or double-stranded HCV RNA induced production of IL-28 and IL-29 by mDC2s; endosomal maturation was required. Production of IFN-α and IFN-λ were linked—IFN-λ increased production of IFN-α by plasmacytoid DCs and IFN-α significantly increased production of IFN-λ. Conclusions: mDC2s are a major source of IFN-λ production by PBMCs in response to HCVcc/Huh7.5 cells. mDC2s are activated through the TLR3 pathway, indicating that human DCs efficiently can initiate an immune response against HCV infection. IFN-λ therefore has an important role in HCV infection. [Copyright &y& Elsevier]

Background & Aims: Liver inflammation and injury are mediated by the innate immune response, which is regulated by Toll-like receptors (TLR). Activation of TLR9 induces type I interferons (IFNs) via the interferon regulatory factor (IRF)-7. We investigated the roles of type I IFNs in TLR9-associated liver injury. Methods: Wild-type (WT), IRF7-deficient, and IFN-α/β receptor 1 (IFNAR1)-deficient mice were stimulated with TLR9 or TLR2 ligands. Findings from mice were verified in cultured hepatocytes and liver mononuclear cells (LMNCs) as well as in vivo experiments using recombinant type I IFN and interleukin-1 receptor antagonist (IL-1ra). Results: Type I IFNs were up-regulated during TLR9-associated liver injury in WT mice. IRF7- and IFNAR1-deficient mice, which have disruptions in type I IFN production or signaling, respectively, had increased liver damage and inflammation, decreased recruitment of dendritic cells, and increased production of tumor necrosis factor α by LMNCs. These findings indicate that type I IFNs have anti-inflammatory activities in liver. IL-1ra, which is produced by LMNCs and hepatocytes, is an IFN-regulated antagonist of the proinflammatory cytokine IL-1β; IRF7- and IFNAR1-deficient mice had decreased levels of IL-1ra compared with WT mice. IL-1ra protected cultured hepatocytes from IL-1β–mediated sensitization to cytotoxicity from tumor necrosis factor α. In vivo exposure to type I IFN, which induced IL-1ra, or administration of IL-1ra reduced TLR9-associated liver injury; the protective effect of type I IFNs therefore appears to be mediated by IFN-dependent induction of IL-1ra. Conclusions: Type I IFNs have anti-inflammatory effects mediated by endogenous IL-1ra, which regulates the extent of TLR9-induced liver damage. Type I IFN signaling is therefore required for protection from immune-mediated liver injury. [ABSTRACT FROM AUTHOR]

Background & Aims: We aimed to identify the incidence and predictors of de novo gastroesophageal variceal formation and progression in a large cohort of patients with chronic hepatitis C and advanced fibrosis. Methods: All participants in the Hepatitis C Antiviral Long-Term Treatment against Cirrhosis Trial were offered an endoscopy before treatment and again after 4 years. Patients with varices at baseline also had an endoscopy at 2 years. Baseline laboratory and clinical parameters were analyzed as predictors of de novo variceal formation and variceal progression. Results: De novo varices developed in 157 of the 598 (26.2%) patients. Most of the new varices were small (76.4%) and only 1% of patients developed variceal hemorrhage. The likelihood of developing varices was associated with subject race (Hispanic > Caucasian > African American; P = .0005), lower baseline levels of albumin (P = .051), and higher levels of hyaluronic acid (P < .001) with an area under the receiver operating characteristic curve = .70. Among 210 patients with existing gastroesophageal varices, 74 (35.2%) had variceal progression or bleeding during follow-up. Patients with higher baseline ratios of serum aspartate/alanine aminotransferase (P = .028) and lower platelet counts (P = .0002) were at greatest risk of variceal progression (area under the receiver operating characteristic = .72). Prolonged, low-dose peginterferon-α2a therapy and β-blockers did not influence the risk of developing new or enlarging varices. Conclusion: Development of varices in patients with chronic hepatitis C is associated with patient race/ethnicity and laboratory markers of disease severity. Prolonged low-dose peginterferon-α2a therapy and β-blockers do not reduce the risk of variceal development or progression. [Copyright &y& Elsevier]