Ductular Reaction Research Articles

THU320 - Ductular reaction and its microenvironment is aetiology driven

THU320 - Ductular reaction and its microenvironment is aetiology driven

GLI1, but not smoothened-dependent, signaling in hepatic progenitor cells promotes a ductular reaction, which aggravates liver fibrosis

GLI1, but not smoothened-dependent, signaling in hepatic progenitor cells promotes a ductular reaction, which aggravates liver fibrosis

Neutrophils are recruited at the periportal area in alcoholic liver disease and promote ductular reaction expansion

Neutrophils are recruited at the periportal area in alcoholic liver disease and promote ductular reaction expansion

Predicting native liver injury and survival in biliary atresia

Several patient and treatment related factors significantly modify outcomes of biliary atresia. The extremely variable prognosis mandates intensive postoperative monitoring following portoenterostomy. Accurate prediction of outcome and progression of liver injury would enable individualized treatment and follow-up protocols, patient counseling and meaningful stratification of patients into clinical trials. While results on most biomarkers of cholestasis, hepatocyte function, fibrosis and inflammation studied so far are inconsistent or have not been validated in independent patient cohorts, postoperative serum bilirubin level 3 months after portoenterostomy remains the most accurate clinically feasible predictor of native liver survival. Although liver stiffness and a novel marker of cholangiocyte integrity, serum matrix metalloproteinase-7, correlate with liver fibrosis and may discriminate biliary atresia from other causes of neonatal cholestasis, further information on their ability to predict portoenterostomy outcomes is needed. Recent gene expression profiling has shown promise in overcoming the sampling error associated with histological quantification of liver fibrosis, and provides an important possibility to stratify patients for clinical trials according to the prognosis of native liver survival already preoperatively. As activity and extent of ductular reaction is linked with progression of liver fibrosis in cholangiopathies, further research is also warranted to evaluate predictive value of ductular reaction, matrix metalloproteinase-7 and the underlying gene expression signatures in relation to circulating bile acids in biliary atresia. Discovery of accurate predictive tools will ultimately increase our understanding of the unpredictable response to surgery and pathophysiology of progressive liver injury in biliary atresia.

Knockout of the Tachykinin Receptor 1 in the Mdr2−/− (Abcb4−/−) Mouse Model of Primary Sclerosing Cholangitis Reduces Biliary Damage and Liver Fibrosis

Activation of the substance P (SP)/neurokinin 1 receptor (NK1R) axis triggers biliary damage/senescence and liver fibrosis in bile duct ligated and Mdr2-/- (alias Abcb4-/-) mice through enhanced transforming growth factor-β1 (TGF-β1) biliary secretion. Recent evidence indicates a role for miR-31 (MIR31) in TGF-β1-induced liver fibrosis. We aimed to define the role of the SP/NK1R/TGF-β1/miR-31 axis in regulating biliary proliferation and liver fibrosis during cholestasis. Thus, we generated a novel model with double knockout of Mdr2-/- and NK1R-/ (alias Tacr1-/-) to further address the role of the SP/NK1R axis during chronic cholestasis. Invivo studies were performed in the following 12-week-old male mice: (i) NK1R-/-; (ii) Mdr2-/-; and (iii) NK1R-/-/Mdr2-/- (Tacr1-/-/Abcb4-/-) and their corresponding wild-type controls. Liver tissues and cholangiocytes were collected, and liver damage, changes in biliary mass/senescence, and inflammation as well as liver fibrosis were evaluated by both immunohistochemistry in liver sections and real-time PCR. miR-31 expression was measured by real-time PCR in isolated cholangiocytes. Decreased ductular reaction, liver fibrosis, biliary senescence, and biliary inflammation were observed in NK1R-/-/Mdr2-/- mice compared with Mdr2-/- mice. Elevated expression of miR-31 was observed in Mdr2-/- mice, which was reduced in NK1R-/-/Mdr2-/- mice. Targeting the SP/NK1R and/or miR-31 may be a potential approach in treating human cholangiopathies, including primary sclerosing cholangitis.

Approach to the patient with acute severe autoimmune hepatitis.

SummaryAutoimmune hepatitis is associated with varied clinical presentations and natural history, as well as somewhat unpredictable treatment responses. Understanding how to stratify patients who require further escalation of therapy will help clinicians manage these patients. The presentation of acute severe autoimmune hepatitis (AS-AIH) is relatively uncommon, although its prevalence is potentially greater than currently perceived. Previous studies consist of small retrospective single-centre series and are not directly comparable due to the diversity of presentations, disease definitions and non-standardised treatment regimens. We define AS-AIH as those who present acutely with AIH and are icteric with an international normalised ratio ≥1.5 and no evidence of hepatic encephalopathy. Those with hepatic encephalopathy should be defined as having AS-AIH with acute liver failure. In this review, we provide a structured practical approach for diagnosing and managing this unique group of patients.

AGER1 downregulation associates with fibrosis in nonalcoholic steatohepatitis and type 2 diabetes.

Type 2 diabetes is clinically associated with progressive necroinflammation and fibrosis in nonalcoholic steatohepatitis (NASH). Advanced glycation end-products (AGEs) accumulate during prolonged hyperglycemia, but the mechanistic pathways that lead to accelerated liver fibrosis have not been well defined. In this study, we show that the AGEs clearance receptor AGER1 was downregulated in patients with NASH and diabetes and in our NASH models, whereas the proinflammatory receptor RAGE was induced. These findings were associated with necroinflammatory, fibrogenic, and pro-oxidant activity via the NADPH oxidase 4. Inhibition of AGEs or RAGE deletion in hepatocytes in vivo reversed these effects. We demonstrate that dysregulation of NRF2 by neddylation of cullin 3 was linked to AGER1 downregulation and that induction of NRF2 using an adeno-associated virus-mediated approach in hepatocytes in vivo reversed AGER1 downregulation, lowered the level of AGEs, and improved proinflammatory and fibrogenic responses in mice on a high AGEs diet. In patients with NASH and diabetes or insulin resistance, low AGER1 levels were associated with hepatocyte ballooning degeneration and ductular reaction. Collectively, prolonged exposure to AGEs in the liver promotes an AGER1/RAGE imbalance and consequent redox, inflammatory, and fibrogenic activity in NASH.

Prominin-1-expressing hepatic progenitor cells induce fibrogenesis in murine cholestatic liver injury.

Cholestatic liver injury is associated with intrahepatic biliary fibrosis, which can progress to cirrhosis. Resident hepatic progenitor cells (HPCs) expressing Prominin‐1 (Prom1 or CD133) become activated and participate in the expansion of cholangiocytes known as the ductular reaction. Previously, we demonstrated that in biliary atresia, Prom1(+) HPCs are present within developing fibrosis and that null mutation of Prom1 significantly abrogates fibrogenesis. Here, we hypothesized that these activated Prom1‐expressing HPCs promote fibrogenesis in cholestatic liver injury. Using Prom1CreERT2‐nLacZ/+;Rosa26Lsl‐GFP/+ mice, we traced the fate of Prom1‐expressing HPCs in the growth of the neonatal and adult livers and in biliary fibrosis induced by bile duct ligation (BDL). Prom1‐expressing cell lineage labeling with Green Fluorescent Protein (GFP) on postnatal day 1 exhibited an expanded population as well as bipotent differentiation potential toward both hepatocytes and cholangiocytes at postnatal day 35. However, in the adult liver, they lost hepatocyte differentiation potential. Upon cholestatic liver injury, adult Prom1‐expressing HPCs gave rise to both PROM1(+) and PROM1(‐) cholangiocytes contributing to ductular reaction without hepatocyte or myofibroblast differentiation. RNA‐sequencing analysis of GFP(+) Prom1‐expressing HPC lineage revealed a persistent cholangiocyte phenotype and evidence of Transforming Growth Factor‐β pathway activation. When Prom1‐expressing cells were ablated with induced Diphtheria toxin in Prom1CreERT‐nLacZ/+;Rosa26DTA/+ mice, we observed a decrease in ductular reactions and biliary fibrosis typically present in BDL as well as decreased expression of numerous fibrogenic gene markers. Our data indicate that Prom1‐expressing HPCs promote biliary fibrosis associated with activation of myofibroblasts in cholestatic liver injury.

Histochemical and Immunohistochemical Characterizations of Hepatic Trematodiasis in Odontocetes.

Hepatic trematodiasis is a common condition in a number of free-ranging cetacean species, which occasionally result in severe hepatic and/or pancreatic lesions. However, even the basic pathological information of this disease is unknown for the majority of affected species. The current study describes and compares the histomorphology and immune reaction induced by hepatic trematodes of the family Brachycladiidae in the liver of the harbor porpoise (Phocoena phocoena, n = 8), Dall's porpoise (Phocoenoides dalli, n = 8), and Hubbs' beaked whale (Mesoplodon carlhubbsi, n = 2). Immunohistochemistry for eight antibodies (CK19, CD3, Foxp3, CD20, Iba1, CD68, CD163, and CD204) was conducted to analyze the pathology of these parasitic infections. In all three odontocete species, the changes observed in the trematode-affected biliary epithelium were comparable with marked hyperplasia and goblet cell metaplasia, as well as lymphoplasmacytic and eosinophilic inflammation. Additionally, regions of the Glisson's sheath were diffusely and severely fibrotic in all examined species, regardless of the physical presence of trematodes. Differences among the three species included the presence of characteristic lymphoid follicles formed in the fibrotic bile duct walls of only the two porpoise species. In the Hubbs' beaked whale, the degree of lymphoplasmacytic cholangitis was more severe, and ductular reaction was generally more prominent. In terms of the overall macrophage population among the three species, CD163- and CD204-positive cells (M2 macrophages) outnumbered Iba1- and CD68-positive cells (M1 macrophages), indicating a chronic infection stage in all analyzed individuals. Species-specific differences among the infiltrating macrophages included numbers of CD68-positive cells being significantly more abundant in the harbor porpoises, whereas CD163-positive cells were significantly more numerous in the Dall's porpoises. The numbers of CD204-positive macrophages were higher in the Hubbs' beaked whales compared to those in the porpoises. Trematode species of the harbor and Dall's porpoises were Campula oblonga, while they were Oschmarinella macrorchis in the Hubbs' beaked whales. This study concludes that interspecies differences in the tissue reactions to hepatic trematode infections are present among odontocete species and that the immune reaction varies depending on the species. This information aids in furthering our understanding of the pathogenesis of hepatic trematodiasis in cetaceans.

Human Pluripotent Stem Cell-Derived Organoids as Models of Liver Disease

There are few invitro models for studying the 3-dimensional interactions among different liver cell types during organogenesis or disease development. We aimed to generate hepatic organoids that comprise different parenchymal liver cell types and have structural features of the liver, using human pluripotent stem cells. We cultured H1 human embryonic stem cells (WA-01, passage 27-40) and induced pluripotent stem cells (GM23338) with a series of chemically defined and serum-free media to induce formation of posterior foregut cells, which were differentiated in 3 dimensions into hepatic endoderm spheroids and stepwise into hepatoblast spheroids. Hepatoblast spheroids were reseeded in a high-throughput format and induced to form hepatic organoids; development of functional bile canaliculi was imaged live. Levels of albumin and apolipoprotein B were measured in cell culture supernatants using an enzyme-linked immunosorbent assay. Levels of gamma glutamyl transferase and alkaline phosphatase were measured in cholangiocytes. Organoids were incubated with troglitazone for varying periods and bile transport and accumulation were visualized by live-imaging microscopy. Organoids were incubated with oleic and palmitic acid, and formation of lipid droplets was visualized by staining. We compared gene expression profiles of organoids incubated with free fatty acids or without. We also compared gene expression profiles between liver tissue samples from patients with nonalcoholic steatohepatitis (NASH) versus without. We quantified hepatocyte and cholangiocyte populations in organoids using immunostaining and flow cytometry; cholangiocyte proliferation of cholangiocytes was measured. We compared the bile canaliculi network in the organoids incubated with versus without free fatty acids by live imaging. Cells in organoids differentiated into hepatocytes and cholangiocytes, based on the expression of albumin and cytokeratin 7. Hepatocytes were functional, based on secretion of albumin and apolipoprotein B and cytochrome P450 activity; cholangiocytes were functional, based on gamma glutamyl transferase and alkaline phosphatase activity and proliferative responses to secretin. The organoids organized a functional bile canaliculi system, which was disrupted by cholestasis-inducing drugs such as troglitazone. Organoids incubated with free fatty acids had gene expression signatures similar to those of liver tissues from patients with NASH. Incubation of organoids with free fatty acid-enriched media resulted in structural changes associated with nonalcoholic fatty liver disease, such as decay of bile canaliculi network and ductular reactions. We developed a hepatic organoid platform with human cells that can be used to model complex liver diseases, including NASH.

Multidimensional imaging of liver injury repair in mice reveals fundamental role of the ductular reaction

Upon severe and/or chronic liver injury, ectopic emergence and expansion of atypical biliary epithelial-like cells in the liver parenchyma, known as the ductular reaction, is typically induced and implicated in organ regeneration. Although this phenomenon has long been postulated to represent activation of facultative liver stem/progenitor cells that give rise to new hepatocytes, recent lineage-tracing analyses have challenged this notion, thereby leaving the pro-regenerative role of the ductular reaction enigmatic. Here, we show that the expanded and remodelled intrahepatic biliary epithelia in the ductular reaction constituted functional and complementary bile-excreting conduit systems in injured parenchyma where hepatocyte bile canalicular networks were lost. The canalicular collapse was an incipient defect commonly associated with hepatocyte injury irrespective of cholestatic statuses, and could sufficiently provoke the ductular reaction when artificially induced. We propose a unifying model for the induction of the ductular reaction, where compensatory biliary epithelial tissue remodeling ensures bile-excreting network homeostasis.

Biliary damage and liver fibrosis are ameliorated in a novel mouse model lacking l-histidine decarboxylase/histamine signaling

Primary sclerosing cholangitis (PSC) is characterized by biliary damage and fibrosis. Multidrug resistance-2 gene knockout (Mdr2−/−) mice and PSC patients have increased histamine (HA) levels (synthesized by l-histidine decarboxylase, HDC) and HA receptor (HR) expression. Cholestatic HDC−/− mice display ameliorated biliary damage and hepatic fibrosis. The current study evaluated the effects of knockout of HDC−/− in Mdr2−/− mice (DKO) on biliary damage and hepatic fibrosis. WT, Mdr2−/− mice, and homozygous DKO mice were used. Selected DKO mice were treated with HA. We evaluated liver damage along with HDC expression and HA serum levels. Changes in ductular reaction were evaluated along with liver fibrosis, inflammation and bile acid signaling pathways. The expression of H1HR/PKC-α/TGF-β1 and H2HR/pERK/VEGF-C was determined. In vitro, cholangiocyte lines were treated with HA with/without H1/H2 inhibitors before measuring: H1/H2HR, TGF-β1, and VEGF-C expression. Knockout of HDC ameliorates hepatic damage, ductular reaction, fibrosis, inflammation, bile acid signaling and H1HR/PKC-α/TGF-β1 and H2HR/pERK/VEGF-C signaling. Reactivation of the HDC/HA axis increased these parameters. In vitro, stimulation with HA increased HR expression and PKC-α, TGF-β1, and VEGF-C expression, which was reduced with HR inhibitors. Our data demonstrate the key role for the HDC/HA axis in the management of PSC progression.

Sa1940 ENDOSCOPIC SLEEVE GASTROPLASTY IMPROVES NONALCOHOLIC FATTY LIVER DISEASE–RELATED LIVER DAMAGE IN YORKSHIRE PIGS BY RESHAPING CELLULAR INTERACTIONS AND HEPATIC ADIPOCYTOKINE PRODUCTION

To investigate whether the modulation of local cellular cross-talks and the modification of hepatic adipocytokine expression could mechanistically explain the improvement of liver histopathology after Endoscopic Sleeve Gastroplasty (ESG) in Yorkshire Pigs with nonalcoholic fatty liver disease (NAFLD). Fifteen male Yorkshire pigs with similar weight were selected in separate compartments and fed with high-fat diets. After 8 weeks of feeding, they were randomly divided into a control group, a sham operation group, and an ESG group. Yorkshire pigs in the ESG group underwent ESG and York pigs in the sham operation group underwent sham surgery. Gastroscopy and upper gastrointestinal angiography were reviewed at 4 weeks, 8 weeks, and 12 weeks after surgery to confirm the success of ESG. York pigs were sacrificed at 12 weeks after surgery, blood samples were collected, and serum TG, TC, and free fatty acids were measured by ELISA. The liver shape of York pigs was observed, liver tissues were taken, and HE staining was performed. Hepatic progenitor cells, hepatic stellate cells (HSCs), macrophages, and adipocytokines were evaluated by immunohistochemistry and immunofluorescence. Compared with the sham operation group, liver biopsy samples demonstrated a significant improvement of NAFLD Activity Score and fibrosis. Immunohistochemistry indicated a significant reduction of hepatocyte cell cycle arrest, ductular reaction, activated HSC, and macrophage number compared with the sham operation group. The activation state of HSC was accompanied by modification in the expression of the autophagy marker LC3. Hepatocyte expression of adiponectin from ESG was significant higher than the sham operation group. Moreover, ESG caused decreased resistin expression in Sox9+ hepatic progenitor cells compared with the sham operation group. The number of S100A9+ macrophages was also reduced by ESG correlating with resistin expression. Finally, serum levels of proinflammatory cytokines significantly correlated with macrophages and activated HSC numbers. The histologic improvement induced by ESG is associated with the reduced activation of local cellular compartments (hepatic progenitor cells, HSCs, and macrophages), thus, strengthening the role of cellular interactions and hepatic adipocytokine production in the pathogenesis of NAFLD.

A novel non-bile acid FXR agonist EDP-305 potently suppresses liver injury and fibrosis without worsening of ductular reaction.

BackgroundEDP‐305 is a novel and potent farnesoid X receptor (FXR) agonist, with no/minimal cross‐reactivity to TGR5 or other nuclear receptors. Herein we report therapeutic efficacy of EDP‐305, in direct comparison with the first‐in‐class FXR agonist obeticholic acid (OCA), in mouse models of liver disease.MethodsEDP‐305 (10 and 30 mg/kg/day) or OCA (30mg/kg/day) was tested in mouse models of pre‐established biliary fibrosis (BALBc.Mdr2‐/‐, n = 9‐12/group) and steatohepatitis induced by methionine/choline‐deficient diet (MCD, n = 7‐12/group). Effects on biliary epithelium were evaluated in vivo and in primary EpCAM + hepatic progenitor cell (HPC) cultures.ResultsIn a BALBc.Mdr2‐/‐ model, EDP‐305 reduced serum transaminases by up to 53% and decreased portal pressure, compared to untreated controls. Periportal bridging fibrosis was suppressed by EDP‐305 at both doses, with up to a 39% decrease in collagen deposition in high‐dose EDP‐305. In MCD‐fed mice, EDP‐305 treatment reduced serum ALT by 62% compared to controls, and profoundly inhibited perisinusoidal ‘chicken wire’ fibrosis, with over 80% reduction in collagen deposition. In both models, treatment with 30mg/kg OCA reduced serum transaminases up to 30%, but did not improve fibrosis. The limited impact on fibrosis was mediated by cholestasis‐independent worsening of ductular reaction by OCA in both disease models; OCA but not EDP‐305 at therapeutic doses promoted ductular proliferation in healthy mice and favoured differentiation of primary HPC towards cholangiocyte lineage in vitro.ConclusionsEDP‐305 potently improved pre‐established liver injury and hepatic fibrosis in murine biliary and metabolic models of liver disease, supporting the clinical evaluation of EDP‐305 in fibrotic liver diseases including cholangiopathies and non‐alcoholic steatohepatitis.

NFkB mediated sustained inflammation promotes hepatobiliary injury in Sickle Cell Disease

Abstract Hepatic crisis is an emergent complication affecting sickle cell disease (SCD) patients, however, the molecular mechanism of sickle cell hepatobiliary injury remains poorly understood. Using the knock-in humanized mouse model of SCD and SCD patient blood, we sought to mechanistically characterize SCD-associated hepatopathophysiology applying our recently developed quantitative liver intravital imaging, RNA sequence analysis, and biochemical approaches. SCD mice manifested sinusoidal ischemia, progressive hepatomegaly, progressive inflammation, hyperbilirubinemia, and increased ductular reaction under basal condition. NFkB activation in the SCD mice liver inhibited FXR signaling and its downstream targets, leading to loss of canallicular bile transport, sustained inflammation and altered bile acid pool. Intravital imaging revealed impaired bile secretion into the bile canaliculi, which was secondary to loss of canallicular bile transport and bile acid metabolism, leading to intrahepatic bile accumulation in SCD mice liver. These findings are the first to identify that NFkB-FXR dependent impaired bile secretion promotes intrahepatic bile accumulation, which contributes to hepatobiliary injury and liver inflammation in SCD. Improved understanding of these processes could potentially benefit the development of new therapies to treat sickle cell hepatic crisis.

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Hedgehog Signaling Demarcates a Niche of Fibrogenic Peribiliary Mesenchymal Cells

In response to tissue injury, stromal cells secrete extracellular matrix (ECM) components that remodel the tissue and lead to fibrosis. Parenchymal stellate cells are the primary contributors to fibrosis in models of hepatocellular and cholestatic injury. The liver comprises different, heterogenous compartments; stromal cells within those compartments might have unique identities and regional functions. The portal tract contains the bile duct, which is surrounded by stromal cells often called portal fibroblasts. We investigated the contributions of these cells to hepatic injury. We performed studies with Gli1:CreERT2;Rosa26:lox-STOP-lox-tdTomato mice. Mice underwent bile duct ligation or were fed 3,5-diethoxycarbonyl-1,4-dihydrocollidine to induce cholestatic injury or were given carbon tetrachloride to induce liver fibrosis. Liver tissues were collected and analyzed by histology and immunofluorescence, and mesenchymal cells were isolated. We performed lineage tracing experiments to determine the fates of peribiliary mesenchymal cells (PMCs) that surround the bile duct after cholestatic and hepatocellular injury. We used cell sorting combined with RNA sequencing to isolate stellate cells and PMCs, and we identified determinants of cell identity within each population. Liver tissues were obtained from patients with primary sclerosing cholangitis, alcoholic liver disease, or nonalcoholic steatohepatitis or individuals without disease and were analyzed by quantitative reverse transcription polymerase chain reaction. Gli1 was a marker of mesenchymal cells that surround the biliary tree but not epithelial cells of the canals of Hering. Lineage-traced Gli1+ PMCs proliferated and acquired a myofibroblast phenotype after cholestatic injury; Gli1+ PMCs were found only surrounding the main duct of a portal tract but not the epithelial cells of the ductular reaction, which were instead encased by stellate cells. Compared with stellate cells, Gli1+ PMCs expressed a different subset of genes, including genes that are markers of active hedgehog signaling, Osr1 (encodes a transcription factor), and ECM-related genes. Loss of hedgehog signaling reduced expression of Osr1 and PMC-specific ECM genes. Liver tissues from patients with liver disease had increased expression of genes that define PMC identity compared with control liver tissues. In lineage-tracing studies of mice, we found that Gli1+ PMCs are a subset of stromal cells characterized by active hedgehog signaling that proliferate, acquire a myofibroblast phenotype, and surround the biliary tree in response to cholestatic injury.

Mammalian Target of Rapamycin Complex 2 Signaling Is Required for Liver Regeneration in a Cholestatic Liver Injury Murine Model

Cholestatic liver injury may lead to a series of hepatobiliary syndromes, which can progress to cirrhosis and impaired liver regeneration, eventually resulting in liver-related death. Mammalian target of rapamycin complex 2 (mTORC2) is a major regulator of liver metabolism and tumor development. However, the role of mTORC2 signaling in cholestatic liver injury has not been characterized to date. In this study, we generated liver-specific Rictor knockout mice to block the mTORC2 signaling pathway. Mice were treated with 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) to induce cholestatic liver injury. DDC feeding induced cholestatic liver injury and ductular reaction as well as activation of the mTORC2/Akt signaling pathway in wild-type mice. Loss of mTORC2 led to significantly decreased oval cell expansion after DDC feeding. Mechanistically, this phenotype was independent of mTORC1/fatty acid synthase cascade (Fasn) or yes-associated protein (Yap) signaling. Notch pathway was instead strongly inhibited during DDC-induced cholestatic liver injury in liver-specific Rictor knockout mice. Furthermore, mTORC2 deficiency in adult hepatocytes did not inhibit ductular reaction in this cholestatic live injury mouse model. Our results indicated that mTORC2 signaling effectively regulates liver regeneration by inducing oval cell proliferation. Liver progenitor cells or bile duct cells, rather than mature hepatocytes, would be the major source of ductular reaction in DDC-induced cholestatic liver injury.

ECM1: A CTGF Binding Protein Inhibiting Ductular Reaction and Liver Fibrosis

IntroductionExtracellular matrix protein 1 (ECM1) has inhibitory roles against transforming growth factor (TGF)β activation and liver fibrosis. We have identified ECM1 as binding protein for connective tissue growth factor (CTGF) in yeast two‐hybrid analysis. This study aims to determine whether ECM1 binding inhibits CTGF‐mediated ductular reaction and liver fibrosis.MethodsMice were fed with 3,5‐diethoxycarbonyl‐1,4‐dihydrocollidine (DDC) to induce ductular reaction and liver fibrosis. ECM1 was overexpressed in adenovirus and intravenously injected into animals before DDC feeding. ECM1 interaction with CTGF, and their effects on liver injury after DDC feeding were analyzed.ResultsECM1 downregulation was correlated with CTGF upregulation during DDC‐induced liver injury. ECM1 overexpression after DDC feeding caused low levels of EpCAM and Sox9 mRNAs, small areas of EpCAM+ cells, and few proliferating ductular epithelial cells in comparison to controls that received GFP adenovirus. Weak fibrogenesis was also observed in the Ecm1 overexpressing livers, as evidenced by low levels of fibrosis‐related genes, small fibrotic areas in staining with α smooth muscle actin antibody and Sirius red as well as low collagen production determined by hepatic hydroxyproline content. Finally, we found that ECM1 could interact with CTGF and integrin αvβ6 leading to low TGFβ activation in vitro and in vivo.ConclusionThese observations indicate that ECM1 is a novel binding protein for CTGF. Its overexpression significantly reduces DDC‐induced ductular reaction and fibrogenic reaction, supporting anti‐fibrotic potentials of this molecule for the treatment of chronic liver disease.Support or Funding InformationThis study is supported by National Institutes of Health NIAAA KO1AA024174 grant and Children Miracle Research Foundation grant awarded to L Pi.

Mast Cell Signaling Regulates Biliary Farnesoid X Receptor and Apical Sodium Bile Acid Transporter Expression During Cholestatic Liver Injury

BackgroundChronic liver diseases and cholangiopathies (targets cholangiocytes) are diagnosed at advanced stages leading to poor prognosis. Mast cells (MCs) infiltrate the liver during damage, release histamine (HA) and act via H1‐H4 HA receptors (HRs). Cholangiocytes and MCs express apical sodium bile acid transporter (ASBT); farnesoid X receptor (FXR) and H2HR. Introduction of MCs into C57BL/6 (WT) and MC deficient (KitW‐sh) mice increases liver damage, biliary proliferation/liver fibrosis, and total bile acid (TBA) levels. We aimed to determine if loss of MC FXR signaling alters biliary FXR and ASBT, injury and hepatic fibrosis via HA/H2HR signaling.MethodsWT or KitW‐sh mice were subjected to tail vein injection of cultured MCs (ATCC®) pretreated with PBS (PBS‐MC) to induce liver damage or the FXR inhibitor, Z‐guggulsterone (10μM, FXR‐MC) and sacrificed after 3 days. H&E was used to determine pathological changes. Ductular reaction was determined by CK‐19 staining. Biliary proliferation and hepatic senescence were evaluated by Ki‐67 and SA‐b‐galactosidase staining. Hepatic fibrosis was determined by Sirius Red staining. Hepatic stellate cell (HSC) presence was determined by immunofluorescence (IF). Biliary senescence was determined by IF and qPCR. Cholangiocyte FXR and ASBT expression was determined by staining and qPCR in cholangiocytes. Senescence associated secretory phenotypes (SASPs) and HA secretion were measured by EIA in serum and cholangiocyte supernatants. H2HR expression was evaluated in isolated cholangiocytes. TBAs were measured in serum and liver tissues. In vitro, cultured MCs were treated with PBS or Z‐guggulsterone (10μM, 48 hr). Treated MC supernatants were placed on cholangiocytes prior to evaluating biliary ASBT and H2HR expression and secretion of HA, TGF‐b1 and IL‐1b by qPCR and EIA, respectively. In human tissue from patients with PSC or PBC, biliary ASBT, FXR and MC infiltration (marked by tryptase) was measured by IHC.ResultsHepatic damage, ductular reaction, biliary senescence, ASBT expression and liver fibrosis were induced in WT and KitW‐sh mice injected with PBS‐MC; whereas, these parameters were reversed in mice injected with FXR‐MCs. HA secretion and H2HR expression increased in serum and cholangiocytes, respectively in WT and KitW‐sh mice injected with PBS‐MC, but were reduced in mice injected with FXR‐MC. Hepatic and serum TBA increased in WT and KitW‐sh mice injected with PBS‐MC and were reduced in FXR‐MC groups. In vitro, stimulation with MC supernatant increased biliary ASBT, FXR, H2HR, HA, TGF‐b1 and IL‐1b expression. These parameters decreased in cholangiocytes treated with FXR‐MC supernatant. In human tissues, upregulation of MCs was coupled with increased biliary FXR and ASBT expression.ConclusionsReintroduction of MCs recapitulates cholestatic liver injury in WT and KitW‐sh mice. Inhibition of MC FXR signaling decreases biliary ASBT expression, liver injury and hepatic fibrosis via downregulation of HA/H2HR signaling. Manipulation of BA transporters, receptors and MC mediators may be a therapeutic route for patients with cholestatic liver damage.Support or Funding InformationNIH NIDDK R01s, VA Merit, IUSOM