Background & Aims Hepatocyte cellular dysfunction and death induced by lipids and macrophage-associated inflammation are characteristics of nonalcoholic steatohepatitis (NASH). The fatty acid ...palmitate can activate death receptor 5 (DR5) on hepatocytes, leading to their death, but little is known about how this process contributes to macrophage-associated inflammation. We investigated whether lipid-induced DR5 signaling results in the release of extracellular vesicles (EVs) from hepatocytes, and whether these can induce an inflammatory macrophage phenotype. Methods Primary mouse and human hepatocytes and Huh7 cells were incubated with palmitate, its metabolite lysophosphatidylcholine, or diluent (control). The released EV were isolated, characterized, quantified, and applied to macrophages. C57BL/6 mice were placed on chow or a diet high in fat, fructose, and cholesterol to induce NASH. Some mice also were given the ROCK1 inhibitor fasudil; 2 weeks later, serum EVs were isolated and characterized by immunoblot and nanoparticle-tracking analyses. Livers were collected and analyzed by histology, immunohistochemistry, and quantitative polymerase chain reaction. Results Incubation of primary hepatocytes and Huh7 cells with palmitate or lysophosphatidylcholine increased their release of EVs, compared with control cells. This release was reduced by inactivating mediators of the DR5 signaling pathway or rho-associated, coiled-coil-containing protein kinase 1 (ROCK1) inhibition. Hepatocyte-derived EVs contained tumor necrosis factor-related apoptosis-inducing ligand and induced expression of interleukin 1β and interleukin 6 messenger RNAs in mouse bone marrow–derived macrophages. Activation of macrophages required DR5 and receptor-interacting protein kinase 1. Administration of the ROCK1 inhibitor fasudil to mice with NASH reduced serum levels of EVs; this reduction was associated with decreased liver injury, inflammation, and fibrosis. Conclusions Lipids, which stimulate DR5, induce release of hepatocyte EVs, which activate an inflammatory phenotype in macrophages. Strategies to inhibit ROCK1-dependent release of EVs by hepatocytes might be developed for the treatment of patients with NASH.
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•Peribiliary macrophages are increased in PSC and animal models of PSC.•Both M1-like and M2-like peribiliary macrophages are increased.•Genetic and pharmacologic CCR2 inhibition ...restrains monocyte recruitment.•CCR2 inhibition reduces fibrosis and cholestasis in animal models of PSC.•These studies support the use of CCR2 inhibitors in human PSC.
Macrophages contribute to liver disease, but their role in cholestatic liver injury, including primary sclerosing cholangitis (PSC), is unclear. We tested the hypothesis that macrophages contribute to the pathogenesis of, and are therapeutic targets for, PSC.
Immune cell profile, hepatic macrophage number, localization and polarization, fibrosis, and serum markers of liver injury and cholestasis were measured in an acute (intrabiliary injection of the inhibitor of apoptosis antagonist BV6) and chronic (Mdr2−/− mice) mouse model of sclerosing cholangitis (SC). Selected observations were confirmed in liver specimens from patients with PSC. Because of the known role of the CCR2/CCL2 axis in monocyte/macrophage chemotaxis, therapeutic effects of the CCR2/5 antagonist cenicriviroc (CVC), or genetic deletion of CCR2 (Ccr2−/− mice) were determined in BV6-injected mice.
We found increased peribiliary pro-inflammatory (M1-like) and alternatively-activated (M2-like) monocyte-derived macrophages in PSC compared to normal livers. In both SC models, genetic profiling of liver immune cells identified a predominance of monocytes/macrophages; immunohistochemistry confirmed peribiliary monocyte-derived macrophage recruitment (M1>M2-polarized), which paralleled injury onset and was reversed upon resolution in acute SC mice. PSC, senescent and BV6-treated human cholangiocytes released monocyte chemoattractants (CCL2, IL-8) and macrophage-activating factors in vitro. Pharmacological inhibition of monocyte recruitment by CVC treatment or CCR2 genetic deletion attenuated macrophage accumulation, liver injury and fibrosis in acute SC.
Peribiliary recruited macrophages are a feature of both PSC and acute and chronic murine SC models. Pharmacologic and genetic inhibition of peribiliary macrophage recruitment decreases liver injury and fibrosis in mouse SC. These observations suggest monocyte-derived macrophages contribute to the development of SC in mice and in PSC pathogenesis, and support their potential as a therapeutic target.
Primary sclerosing cholangitis (PSC) is an inflammatory liver disease which often progresses to liver failure. The cause of the disease is unclear and therapeutic options are limited. Therefore, we explored the role of white blood cells termed macrophages in PSC given their frequent contribution to other human inflammatory diseases. Our results implicate macrophages in PSC and PSC-like diseases in mice. More importantly, we found that pharmacologic inhibition of macrophage recruitment to the liver reduces PSC-like liver injury in the mouse. These exciting observations highlight potential new strategies to treat PSC.
S100B is a calcium-binding protein that governs calcium-mediated responses in a variety of cells-especially neuronal and glial cells. It is also extensively investigated as a potential biomarker for ...several disease conditions, especially neurodegenerative ones. In order to establish S100B as a viable pharmaceutical target, it is critical to understand its mechanistic role in signaling pathways and its interacting partners. In this report, we provide evidence to support a calcium-regulated interaction between S100B and the neuronal calcium sensor protein, neurocalcin delta both in vitro and in living cells. Membrane overlay assays were used to test the interaction between purified proteins in vitro and bimolecular fluorescence complementation assays, for interactions in living cells. Added calcium is essential for interaction in vitro; however, in living cells, calcium elevation causes translocation of the NCALD-S100B complex to the membrane-rich, perinuclear trans-Golgi network in COS7 cells, suggesting that the response is independent of specialized structures/molecules found in neuronal/glial cells. Similar results are also observed with hippocalcin, a closely related paralog; however, the interaction appears less robust in vitro. The N-terminal region of NCALD and HPCA appear to be critical for interaction with S100B based on in vitro experiments. The possible physiological significance of this interaction is discussed.
In most exposed individuals, hepatitis C virus (HCV) establishes a chronic infection; this long-term infection in turn contributes to the development of liver diseases such as cirrhosis and ...hepatocellular carcinoma. The role of antibodies directed against HCV in disease progression is poorly understood. Neutralizing antibodies (nAbs) can prevent HCV infection in vitro and in animal models. However, the effects of nAbs on an established HCV infection are unclear. We demonstrate that three broadly nAbs-AR3A, AR3B, and AR4A-delivered with adeno-associated viral vectors can confer protection against viral challenge in humanized mice. Furthermore, we provide evidence that nAbs can abrogate an ongoing HCV infection in primary hepatocyte cultures and in a human liver chimeric mouse model. These results showcase a therapeutic approach to interfere with HCV infection by exploiting a previously unappreciated need for HCV to continuously infect new hepatocytes to sustain a chronic infection.
Herein, we have identified cross-talk between the Hippo and fibroblast growth factor receptor (FGFR) oncogenic signaling pathways in cholangiocarcinoma (CCA). Yes-associated protein (YAP) nuclear ...localization and up-regulation of canonical target genes was observed in CCA cell lines and a patient-derived xenograft (PDX). Expression of FGFR1, -2, and -4 was identified in human CCA cell lines, driven, in part, by YAP coactivation of TBX5. In turn, FGFR signaling in a cell line with minimal basal YAP expression induced its cellular protein expression and nuclear localization. Treatment of YAP-positive CCA cell lines with BGJ398, a pan-FGFR inhibitor, resulted in a decrease in YAP activation. FGFR activation of YAP appears to be driven largely by FGF5 activation of FGFR2, as siRNA silencing of this ligand or receptor, respectively, inhibited YAP nuclear localization. BGJ398 treatment of YAP-expressing cells induced cell death due to Mcl-1 depletion. In a YAP-associated mouse model of CCA, expression of FGFR 1, 2, and 4 was also significantly increased. Accordingly, BGJ398 treatment was tumor-suppressive in this model and in a YAP-positive PDX model. These preclinical data suggest not only that the YAP and Hippo signaling pathways culminate in an Mcl-1-regulated tumor survival pathway but also that nuclear YAP expression may be a biomarker to employ in FGFR-directed therapy.
c‐Myc induction drives cholestatic liver injury and cholangiocarcinoma (CCA) in mice, and induction of Maf proteins (MafG and c‐Maf) contributes to cholestatic liver injury, whereas ...S‐adenosylmethionine (SAMe) administration is protective. Here, we determined whether there is interplay between c‐Myc, Maf proteins, and methionine adenosyltransferase α1 (MATα1), which is responsible for SAMe biosynthesis in the liver. We used bile duct ligation (BDL) and lithocholic acid (LCA) treatment in mice as chronic cholestasis models, a murine CCA model, human CCA cell lines KMCH and Huh‐28, human liver cancer HepG2, and human CCA specimens to study gene and protein expression, protein‐protein interactions, molecular mechanisms, and functional outcomes. We found that c‐Myc, MATα1 (encoded by MAT1A), MafG, and c‐Maf interact with one another directly. MAT1A expression fell in hepatocytes and bile duct epithelial cells during chronic cholestasis and in murine and human CCA. The opposite occurred with c‐Myc, MafG, and c‐Maf expression. MATα1 interacts mainly with Mnt in normal liver, but this switches to c‐Maf, MafG, and c‐Myc in cholestatic livers and CCA. Promoter regions of these genes have E‐boxes that are bound by MATα1 and Mnt in normal liver and benign bile duct epithelial cells that switched to c‐Myc, c‐Maf, and MafG in cholestasis and CCA cells. E‐box positively regulates c‐Myc, MafG, and c‐Maf, but it negatively regulates MAT1A. MATα1 represses, whereas c‐Myc, MafG, and c‐Maf enhance, E‐box‐driven promoter activity. Knocking down MAT1A or overexpressing MafG or c‐Maf enhanced CCA growth and invasion in vivo. Conclusion: There is a novel interplay between MATα1, c‐Myc, and Maf proteins, and their deregulation during chronic cholestasis may facilitate CCA oncogenesis. (Hepatology 2016;64:439‐455)
Primary sclerosing cholangitis (PSC) is an incurable, fibroinflammatory biliary disease for which there is no effective pharmacotherapy. We recently reported cholangiocyte senescence as an important ...phenotype in PSC while others showed that portal macrophages accumulate in PSC. Unfortunately, our ability to explore cholangiocyte senescence and macrophage accumulation has been hampered by limited in vitro models. Thus, our aim was to develop and characterize a three-dimensional (3D) model of normal and diseased bile ducts (cholangioids) starting with normal human cholangiocytes (NHC), senescent NHC (NHC-sen), and cholangiocytes from PSC patients. In 3D culture, NHCs formed spheroids of ~5000 cells with a central lumen of ~150 μm. By confocal microscopy and western blot, cholangioids retained expression of cholangiocyte proteins (cytokeratin 7/19) and markers of epithelial polarity (secretin receptor and GM130). Cholangioids are functionally active, and upon secretin stimulation, luminal size increased by ~80%. Cholangioids exposed to hydrogen peroxide exhibited cellular senescence and the senescence-associated secretory phenotype (SASP; increased IL-6, p21, SA-β-Gal, yH2A.x and p16 expression). Furthermore, cholangioids derived from NHC-sen or PSC patients were smaller and had slower growth than the controls. When co-cultured with THP-1 macrophages, the number of macrophages associated with NHC-sen or PSC cholangioids was five- to seven-fold greater compared to co-culture with non-senescent NHC. We observed that NHC-sen and PSC cholangioids release greater number of extracellular vesicles (EVs) compared to controls. Moreover, conditioned media from NHC-sen cholangioids resulted in an ~2-fold increase in macrophage migration. In summary, we developed a method to generate normal and diseased cholangioids, characterized them morphologically and functionally, showed that they can be induced to senescence and SASP, and demonstrated both EV release and macrophage attraction. This novel model mimics several features of PSC, and thus will be useful for studying the pathogenesis of PSC and potentially identifying new therapeutic targets.
Ductular reactive (DR) cells exacerbate cholestatic liver injury and fibrosis. Herein, we posit that tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) emanates from recruited ...macrophages and restrains DR cell expansion, thereby limiting cholestatic liver injury. Wild type (WT), Trail
and myeloid-specific Trail deleted (Trail
) C57BL/6 mice were exposed to DDC diet-induced cholestatic liver injury, which induced hepatomegaly and liver injury as compared to control diet-fed mice. However, parameters of liver injury, fibrosis, and inflammation were all increased in the Trail
mice as compared to the WT and Trail
mice. High dimensional mass cytometry indicated that cholestasis resulted in increased hepatic recruitment of subsets of macrophages and neutrophils in the Trail
mice. Spatial transcriptomics analysis revealed that the PanCK
cholangiocytes from Trail
mice had increased expression of the known myeloid attractants S100a8, Cxcl5, Cx3cl1, and Cxcl1. Additionally, in situ hybridization of Cxcl1, a potent neutrophil chemoattractant, demonstrated an increased expression in CK19
cholangiocytes of Trail
mice. Collectively, these data suggest that TRAIL from myeloid cells, particularly macrophages, restrains a subset of DR cells (i.e., Cxcl1 positive cells), limiting liver inflammation and fibrosis. Reprogramming macrophages to express TRAIL may be salutary in cholestasis.
Deregulated Hippo pathway signaling is associated with aberrant activation of the downstream effector yes-associated protein (YAP), an emerging key oncogenic mediator in cholangiocarcinoma (CCA). In ...our prior work, we have demonstrated that biliary transduction of YAP along with Akt as a permissive factor induces CCA in mice. To further delineate the mechanisms associated with YAP-associated biliary oncogenesis, we have established seven malignant murine cell lines from our YAP-driven murine CCA model. These cells express the CCA markers SRY (Sex Determining Region Y)-Box 9 (SOX9), cytokeratin (CK)-7 and 19 but lack hepatocyte nuclear factor 4 alpha and alpha-smooth muscle actin, markers of hepatocellular carcinoma and cancer-associated fibroblasts, respectively. Notably, the murine CCA cells can be readily implanted into mouse livers with resultant orthotopic tumor formation. In this unique syngeneic orthotopic murine model, tumors exhibit histopathologic features resembling human CCA. We analyzed transcriptome data from YAP-associated parent CCA tumor nodules and identified a gene expression pattern associated with chromosomal instability, known as CIN25. Similarly, mate-pair sequencing of the murine CCA cells revealed chromosomal missegregation with gains and losses of several whole chromosomes demonstrating aneuploidy. Of the CIN25 genes, forkhead box M1 (Foxm1), a key cell cycle regulator, was the most significantly upregulated CIN25 gene product. Accordingly, small interfering RNA (siRNA)-mediated silencing of YAP as well as FOXM1 inhibition with thiostrepton induced CCA cell death. These preclinical data imply a role for YAP-mediated chromosomal instability in cholangiocarcinoma, and suggest FOXM1 inhibition as a therapeutic target for CCA.
Background and Aims
Liver‐related clinical consequences of non‐alcoholic fatty liver disease (NAFLD) are seen only in the minority of patients with advanced fibrosis. The aim of our study was to ...generate insight into a potential endocrine basis of steatohepatitis with advanced fibrosis in NAFLD.
Methods
Biopsy and blood samples were prospectively collected from patients with medically complicated obesity. Patients were categorized, according to liver histology, into: (i) normal, (ii) simple steatosis (SS), (iii) non‐alcoholic steatohepatitis (NASH) with fibrosis stage (FS) 0–1 and (iv) NASH with FS ≥ 2. A broad panel of potential biomarkers included DHEA‐S, growth hormone (GH), homeostasis model assessment‐insulin resistance (HOMA‐IR), leptin, resistin, adiponectin and cytokeratin 18 (CK‐18) fragments.
Results
We studied 160 patients (mean BMI 46.8 ± 8.2 kg/m2). Liver biopsies demonstrated normal histology in 10%, SS in 45%, NASH with FS 0–1 in 37.5% and NASH with FS ≥ 2 in 7.5%. C‐reactive protein, IL‐6, GH, CK‐18, adiponectin, HOMA‐IR and quantitative insulin sensitivity check index (QUICKI) were significantly associated with NASH in univariate analysis, but overall predictivity of these parameters was low (AUC ROC = 0.62–0.68). In contrast, all patients with NASH with FS ≥ 2 had insulin resistance, as measured by QUICKI, and GH levels <0.45 ng/ml and all but one patient with NASH FS 2–3 had low DHEA levels (<123 μg/dl).
Conclusions
Low serum levels of GH and DHEA are very common in patients with NASH with more advanced fibrosis. Other biomarkers, including CK‐18 fragment levels, have predictivity characteristics that would be of low clinical utility for distinguishing patients with normal histology or SS from those with NASH. These findings demonstrate an endocrine profile associated with advanced fibrosis.
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