Fibrosis in autoimmune and cholestatic liver disease

FGF21-dependent alleviation of cholestasis-induced liver fibrosis by sodium butyrate

Background

The beneficial effects of fibroblast growth factor 21 (FGF21) and sodium butyrate (NaB) on protection against cholestasis-induced liver fibrosis are not well known. This study aimed to explore the effects of FGF21 and NaB on bile duct ligation (BDL)-induced liver fibrosis.

Methods

Wild-type (WT) and FGF21 knockout (KO) mice received BDL surgery for 14 days. Liver fibrosis was assessed by Masson's staining for fibrosis marker expressions at the mRNA or protein levels. Adenovirus-mediated FGF21 overexpression in the WT mice was assessed against BDL damage. BDL surgeries were performed in WT and FGF21 KO mice that were administered either phosphate-buffered saline or NaB. The effects of NaB on the energy metabolism and gut microbiota were assessed using stable metabolism detection and 16S rRNA gene sequencing.

Results

BDL-induced liver fibrosis in the WT mice was accompanied by high induction of FGF21. Compared to the WT mice, the FGF21 KO mice showed more severe liver fibrosis induced by BDL. FGF21 overexpression protected against BDL-induced liver fibrosis, as proved by the decreasing α-SMA at both the mRNA and protein levels. NaB administration enhanced the glucose and energy metabolisms as well as remodeled the gut microbiota. NaB alleviated BDL-induced liver fibrosis in the WT mice but aggravated the same in FGF21 KO mice.

Conclusion

FGF21 plays a key role in alleviating cholestasis-induced liver damage and fibrosis. NaB has beneficial effects on cholestasis in an FGF21-dependent manner. NaB administration can thus be a novel nutritional therapy for treating cholestasis via boosting FGF21 signaling and regulating the gut microbiota.

Blockade of neutrophil extracellular trap components ameliorates cholestatic liver disease in Mdr2 (Abcb4) knockout mice

Primary sclerosing cholangitis (PSC) is an (auto)immune-mediated cholestatic liver disease with a yet unclear etiology. Increasing evidence points to an involvement of neutrophils in chronic liver inflammation and cirrhosis but also liver repair. Here, we investigate the role of the neutrophil extracellular trap (NET) component myeloperoxidase (MPO) and the therapeutic potential of DNase I and of neutrophil elastase (NE) inhibitor GW311616A on disease outcome in the multidrug resistance 2 knockout (Mdr2-/-) mouse, a PSC animal model. Initially, we observed the recruitment of MPO expressing cells and the formation of NETs in liver biopsies of PSC patients and in Mdr2-/- livers. Furthermore, sera of Mdr2-/- mice contained perinuclear anti-neutrophil cytoplasmic antibody (p-ANCA)-like reactivity similar to PSC patient sera. Also, hepatic NE activity was significantly higher in Mdr2-/- mice than in wild type littermates. Flow cytometry analyses revealed that during disease development a highly active neutrophil subpopulation established specifically in the liver of Mdr2-/- mice. However, absence of their MPO activity, as in MPO-deficient Mdr2-/- mice, showed no effect on hepatobiliary disease severity. In contrast, clearance of extracellular DNA by DNase I reduced the frequency of liver-resident neutrophils, plasmacytoid dendritic cells (pDCs) and CD103+ conventional DCs and decreased cholangiocyte injury. Combination of DNase I with a pDC-depleting antibody was additionally hepatocyte-protective. Most importantly, GW311616A, an orally bioavailable inhibitor of human NE, attenuated hepatobiliary injury in a TNFα-dependent manner and damped hyperproliferation of biliary epithelial cells. Further, hepatic immigration and activity of CD11b+ DCs as well as the secretion of IFNγ by hepatic CD4 and CD8 T cells were reduced. Our findings delineate neutrophils as important participants in the immune cell crosstalk that drives cholestatic liver disease and identify NET components as potential therapeutic targets.

The role of donor sex on the post-liver transplant outcomes in patients with primary sclerosing cholangitis

BACKGROUND AND AIMS

Primary sclerosing cholangitis (PSC) can result in hepatic decompensation and require liver transplantation (LT). This study investigates the effect of the sex of the donor and recipient as a prognostic risk factor for adverse outcomes after LT in patients with PSC.

METHODS

UNOS registry was used to select LT patients with PSC from 1987 to 2019. The study cohort was stratified based on the sex of the recipient and further subdivided based on the sex of the donor. The primary endpoints of this study were all-cause mortality and graft failure, which were evaluated using a sequential Cox regression analysis.

RESULTS

This study included 2829 patients; 906 female recipients were transplanted from 441 male donors and 465 female donors. 1923 male recipients were transplanted from 1194 male donors and 729 female donors. Within the mismatch analyses, the male-to-male recipients also had a significantly reduced hazard ratio of graft failure compared to female-to-male transplants [aHR 0.51, 95% confidence interval (CI) 0.33-0.79, P  = 0.003]. No difference in graft failure was observed in the mismatched female recipient subgroup. The mismatched male recipient group also showed a decreased hazard ratio of mortality from graft rejection and respiratory causes. No differences in specific mortality causes were identified in the mismatched female recipient group.

CONCLUSION

This study demonstrated an increase in the risk of graft failure and mortality secondary to graft failure in male recipients of female donor livers. No differences in mortality or graft failure were identified in female recipients of male livers.

Sortilin in biliary epithelial cells promotes ductular reaction and fibrosis during cholestatic injury

Cholestatic injuries are accompanied by a ductular reaction, initiated by proliferation and activation of biliary epithelial cells (BEC), leading to fibrosis. Sortilin (Sort1) facilitates IL-6 secretion and leukemia inhibitory factor (LIF) signaling. This study investigated the interplay between sortilin, IL-6 and LIF in cholestatic injury-induced ductular reaction, morphogenesis of new ducts and fibrosis. Cholestatic injury was induced by bile duct ligation (BDL) in WT and Sort1-/- mice, with or without augmentation of IL-6 or LIF. Mice with BEC sortilin deletion (HgfapcreSort1fl/fl) and controls were subjected to BDL and 3,5-Diethoxycarbonyl-1,4-Dihydrocollidine diet (DDC)-induced cholestatic injury. Sort1-/- mice displayed reduced BEC proliferation and expression of BEC reactive markers. Administration of LIF or IL-6 restored BEC proliferation in Sort1-/- mice, without affecting BEC reactive or inflammatory markers. Sort1-/- mice also displayed impaired morphogenesis, which was corrected by LIF treatment. Similarly, HgfapcreSort1fl/f mice exhibited reduced BEC proliferation, but similar expression of reactive and inflammatory markers. Serum IL-6 and LIF levels were comparable, yet liver pSTAT3 was reduced, indicating that sortilin is essential for co-activation of LIFR/gp130 signaling in BEC, but not for IL-6 secretion. Notably, HgfapcreSortfl/fl mice displayed impaired morphogenesis and diminished fibrosis following BDL and DDC. In conclusion, sortilin-governed engagement of LIF signaling in BEC promotes ductular reaction and morphogenesis during cholestatic injury. Moreover, BEC sortilin is pivotal for the development of fibrosis.

Bile acid-mediated signaling in cholestatic liver diseases

Chronic cholestatic liver diseases, such as primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC), are associated with bile stasis and gradually progress to fibrosis, cirrhosis, and liver failure, which requires liver transplantation. Although ursodeoxycholic acid is effective in slowing the disease progression of PBC, it has limited efficacy in PSC patients. It is challenging to develop effective therapeutic agents due to the limited understanding of disease pathogenesis. During the last decade, numerous studies have demonstrated that disruption of bile acid (BA) metabolism and intrahepatic circulation promotes the progression of cholestatic liver diseases. BAs not only play an essential role in nutrition absorption as detergents but also play an important role in regulating hepatic metabolism and modulating immune responses as key signaling molecules. Several excellent papers have recently reviewed the role of BAs in metabolic liver diseases. This review focuses on BA-mediated signaling in cholestatic liver disease.

Maternal serum Sortilin-1 level as a potential biomarker for intrahepatic cholestasis of pregnancy

Objective: Intrahepatic cholestasis of pregnancy (ICP) is the most common liver disease related to pregnancy in women. Sortilin-1 is a sorting receptor belonging to the vacuolar protein sorting 10 (Vps10p) domain family, and recent studies have shown that Sortilin-1 has a distinct role in the pathogenesis of biliary fibrosis and cirrhosis. We aimed to evaluate maternal serum Sortilin-1 level as a potential biomarker in pregnant women with intrahepatic cholestasis.Materials and methods: A prospective observational cohort study was conducted. We enrolled 80 pregnant women, 49 with the diagnosis of intrahepatic cholestasis of pregnancy and 31 healthy controls. Then, we measured maternal serum Sortilin-1 levels using an enzyme-linked immunosorbent assay method and compared them between groups.Results: The mean Sortilin-1 level in the ICP group was higher than control group (3.3 ± 1.7 ng/mL vs. 2.0 ± 0.6 ng/mL, respectively, p < .001). The receiver operating characteristic curve (ROC) analysis based on maternal serum Sortilin-1 levels to predict the presence of ICP was 85.3% controls [area under the curve (AUC), 0.853; 95% CI, 0.738-0.938, p < .001]. The optimal cutoff value of Sortilin-1 was 2.24 ng/mL (71.4% sensitivity and 74.2% specificity) to detect intrahepatic cholestasis of pregnancy.Conclusion: Elevated maternal serum Sortilin-1 levels are associated with ICP and can be used as a disease biomarker. Sortilin-1 levels can be combined with total bile acids, transaminases, and blood coagulation profile in the follow-up of ICP.

Sorting through the extensive and confusing roles of sortilin in metabolic disease

Sortilin is a post-Golgi trafficking receptor homologous to the yeast vacuolar protein sorting receptor 10 (VPS10). The VPS10 motif on sortilin is a 10-bladed β-propeller structure capable of binding more than 50 proteins, covering a wide range of biological functions including lipid and lipoprotein metabolism, neuronal growth and death, inflammation, and lysosomal degradation. Sortilin has a complex cellular trafficking itinerary, where it functions as a receptor in the trans-Golgi network, endosomes, secretory vesicles, multivesicular bodies, and at the cell surface. In addition, sortilin is associated with hypercholesterolemia, Alzheimer's disease, prion diseases, Parkinson's disease, and inflammation syndromes. The 1p13.3 locus containing SORT1, the gene encoding sortilin, carries the strongest association with LDL-C of all loci in human genome-wide association studies. However, the mechanism by which sortilin influences LDL-C is unclear. Here, we review the role sortilin plays in cardiovascular and metabolic diseases and describe in detail the large and often contradictory literature on the role of sortilin in the regulation of LDL-C levels.

Spatial transcriptomics identifies enriched gene expression and cell types in human liver fibrosis

Liver fibrosis and cirrhosis have limited therapeutic options and represent a serious unmet patient need. Recent use of single‐cell RNA sequencing (scRNAseq) has identified enriched cell types infiltrating cirrhotic livers but without defining the microanatomical location of these lineages thoroughly. To assess whether fibrotic liver regions specifically harbor enriched cell types, we explored whether whole‐tissue spatial transcriptomics combined with scRNAseq and gene deconvolution analysis could be used to localize cell types in cirrhotic explants of patients with end‐stage liver disease (total n = 8; primary sclerosing cholangitis, n = 4; primary biliary cholangitis, n = 2, alcohol‐related liver disease, n = 2). Spatial transcriptomics clearly identified tissue areas of distinct gene expression that strongly correlated with the total area (Spearman r = 0.97, p = 0.0004) and precise location (parenchyma, 87.9% mean congruency; range, 73.1%–97.1%; fibrosis, 68.5% mean congruency; range, 41.0%–91.7%) of liver regions classified as parenchymal or fibrotic by conventional histology. Deconvolution and enumeration of parenchymal and fibrotic gene content as measured by spatial transcriptomics into distinct cell states revealed significantly higher frequencies of ACTA2+ FABP4+ and COL3A1+ mesenchymal cells, IL17RA+ S100A8+ and FCER1G+ tissue monocytes, VCAM1+ SDC3+ Kupffer cells, CCL4+ CCL5+ KLRB1+ and GZMA+ IL17RA+ T cells and HLA‐DR+, CD37+ CXCR4+ and IGHM+ IGHG+ B cells in fibrotic liver regions compared with parenchymal areas of cirrhotic explants. Conclusion: Our findings indicate that spatial transcriptomes of parenchymal and fibrotic liver regions express unique gene content within cirrhotic liver and demonstrate proof of concept that spatial transcriptomes combined with additional RNA sequencing methodologies can refine the localization of gene content and cell lineages in the search for antifibrotic targets.

TJ-M2010-5, A self-developed MyD88 inhibitor, attenuates liver fibrosis by inhibiting the NF-κB pathway

Liver fibrosis is the result of most chronic inflammatory liver damage and seriously endangers human health. However, no drugs have been approved to treat this disease. Previous studies showed that the Toll-like receptors (TLRs)/myeloid differentiation factor-88 (MyD88)/nuclear factor-κB (NF-κB) pathway plays a key role in liver fibrosis. TJ-M2010-5 is a self-developed small molecule MyD88 inhibitor, which has been proven to have a good protective effect in a variety of inflammatory disease models. In the present study, to investigate the anti-fibrotic effect of TJ-M2010-5, mice were injected with carbon tetrachloride (CCl4) in vivo and LX2 cells (a human hepatic stellate cell line) were treated with TGF-β1 in vitro to induce liver fibrosis. In vivo studies showed that TJ-M2010-5 attenuated the CCl4-induced liver damage, collagen accumulation, and the activation of hepatic stellate cells by inhibiting the nuclear transfer of NF-κB. Moreover, in vitro experiments of LX2 cells stimulated with TGF-β1 further indicated that the NF-κB pathway is involved in the development of liver fibrosis. TJ-M2010-5 significantly inhibited the proliferation and activation of LX2 cells. In addition, TJ-M2010-5 upregulated the expression of bone morphogenetic protein and membrane-bound inhibitor (BAMBI) in LX2 cells by blocking the activation of MyD88/NF-κB, thereby inhibiting the phosphorylation of Smad2/3 and the expression of collagen I (COL1A1) induced by TGF-β1. In conclusion, this study illustrates the anti-hepatic fibrosis effect of TJ-M2010-5 and provides a new treatment method for liver fibrosis.

Biofabricated 3D in vitro model of fibrosis-induced abnormal hepatoblast/biliary progenitors' expansion of the developing liver

Congenital disorders of the biliary tract are the primary reason for pediatric liver failure and ultimately for pediatric liver transplant needs. Not all causes of these disorders are well understood, but it is known that liver fibrosis occurs in many of those afflicted. The goal of this study is to develop a simple yet robust model that recapitulates physico-mechanical and cellular aspects of fibrosis mediated via hepatic stellate cells (HSCs) and their effects on biliary progenitor cells. Liver organoids were fabricated by embedding various HSCs, with distinctive abilities to generate mild to severe fibrotic environments, together with undifferentiated liver progenitor cell line, HepaRG, within a collagen I hydrogel. The fibrotic state of each organoid was characterized by examination of extracellular matrix (ECM) remodeling through quantitative image analysis, rheometry, and qPCR. In tandem, the phenotype of the liver progenitor cell and cluster formation was assessed through histology. Activated HSCs (aHSCs) created a more severe fibrotic state, exemplified by a more highly contracted and rigid ECM, as well higher relative expression of TGF-β, TIMP-1, LOXL2, and COL1A2 as compared to immortalized HSCs (LX-2). Within the more severe fibrotic environment, generated by the aHSCs, higher Notch signaling was associated with an expansion of CK19+ cells as well as the formation of larger, more densely populated cell biliary like-clusters as compared to mild and non-fibrotic controls. The expansion of CK19+ cells, coupled with a severely fibrotic environment, are phenomena found within patients suffering from a variety of congenital liver disorders of the biliary tract. Thus, the model presented here can be utilized as a novel in vitro testing platform to test drugs and identify new targets that could benefit pediatric patients that suffer from the biliary dysgenesis associated with a multitude of congenital liver diseases.

Drug-Induced Vanishing Bile Duct Syndrome: From Pathogenesis to Diagnosis and Therapeutics

The most concerned issue in the context of drug/herb-induced chronic cholestasis is vanishing bile duct syndrome. The progressive destruction of intrahepatic bile ducts leading to ductopenia is usually not dose dependent, and has a delayed onset that should be suspected when abnormal serum cholestasis enzyme levels persist despite drug withdrawal. Immune-mediated cholangiocyte injury, direct cholangiocyte damage by drugs or their metabolites once in bile, and sustained exposure to toxic bile salts when biliary epithelium protective defenses are impaired are the main mechanisms of cholangiolar damage. Current therapeutic alternatives are scarce and have not shown consistent beneficial effects so far. This review will summarize the current literature on the main diagnostic tools of ductopenia and its histological features, and the differential diagnostic with other ductopenic diseases. In addition, pathomechanisms will be addressed, as well as the connection between them and the supportive and curative strategies for ductopenia management.

Identification of hepatic fibrosis inhibitors through morphometry analysis of a hepatic multicellular spheroids model

A chronic, local inflammatory milieu can cause tissue fibrosis that results in epithelial-to-mesenchymal transition (EMT), endothelial-to-mesenchymal transition (EndMT), increased abundance of fibroblasts, and further acceleration of fibrosis. In this study, we aimed to identify potential mechanisms and inhibitors of fibrosis using 3D model-based phenotypic screening. We established liver fibrosis models using multicellular tumor spheroids (MCTSs) composed of hepatocellular carcinoma (HCC) and stromal cells such as fibroblasts (WI38), hepatic stellate cells (LX2), and endothelial cells (HUVEC) seeded at constant ratios. Through high-throughput screening of FDA-approved drugs, we identified retinoic acid and forskolin as candidates to attenuate the compactness of MCTSs as well as inhibit the expression of ECM-related proteins. Additionally, retinoic acid and forskolin induced reprogramming of fibroblast and cancer stem cells in the HCC microenvironment. Of interest, retinoic acid and forskolin had anti-fibrosis effects by decreasing expression of α-SMA and F-actin in LX2 cells and HUVEC cells. Moreover, when sorafenib was added along with retinoic acid and forskolin, apoptosis was increased, suggesting that anti-fibrosis drugs may improve tissue penetration to support the efficacy of anti-cancer drugs. Collectively, these findings support the potential utility of morphometric analyses of hepatic multicellular spheroid models in the development of new drugs with novel mechanisms for the treatment of hepatic fibrosis and HCCs.

Cellular Mechanisms of Liver Fibrosis

The liver is a central organ in the human body, coordinating several key metabolic roles. The structure of the liver which consists of the distinctive arrangement of hepatocytes, hepatic sinusoids, the hepatic artery, portal vein and the central vein, is critical for its function. Due to its unique position in the human body, the liver interacts with components of circulation targeted for the rest of the body and in the process, it is exposed to a vast array of external agents such as dietary metabolites and compounds absorbed through the intestine, including alcohol and drugs, as well as pathogens. Some of these agents may result in injury to the cellular components of liver leading to the activation of the natural wound healing response of the body or fibrogenesis. Long-term injury to liver cells and consistent activation of the fibrogenic response can lead to liver fibrosis such as that seen in chronic alcoholics or clinically obese individuals. Unidentified fibrosis can evolve into more severe consequences over a period of time such as cirrhosis and hepatocellular carcinoma. It is well recognized now that in addition to external agents, genetic predisposition also plays a role in the development of liver fibrosis. An improved understanding of the cellular pathways of fibrosis can illuminate our understanding of this process, and uncover potential therapeutic targets. Here we summarized recent aspects in the understanding of relevant pathways, cellular and molecular drivers of hepatic fibrosis and discuss how this knowledge impact the therapy of respective disease.

Fibrotic Events in the Progression of Cholestatic Liver Disease

Cholestatic liver diseases including primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) are associated with active hepatic fibrogenesis, which can ultimately lead to the development of cirrhosis. However, the exact relationship between the development of liver fibrosis and the progression of cholestatic liver disease remains elusive. Periductular fibroblasts located around the bile ducts seem biologically different from hepatic stellate cells (HSCs). The fibrotic events in these clinical conditions appear to be related to complex crosstalk between immune/inflammatory mechanisms, cytokine signalling, and perturbed homeostasis between cholangiocytes and mesenchymal cells. Several animal models including bile duct ligation (BDL) and the Mdr2-knockout mice have improved our understanding of mechanisms underlying chronic cholestasis. In the present review, we aim to elucidate the mechanisms of fibrosis in order to help to identify potential diagnostic and therapeutic targets.

Complexation with Random Methyl-β-Cyclodextrin and (2-Hidroxypropyl)-β-Cyclodextrin Enhances In Vivo Anti-Fibrotic and Anti-Inflammatory Effects of Chrysin via the Inhibition of NF-κB and TGF-β1/Smad Signaling Pathways and Modulation of Hepatic Pro/Anti-Fibrotic miRNA

Chrysin (CHR) is a natural flavonoid with a wide range of pharmacological activities, including hepatoprotection, but poor water solubility. By including water-soluble hydroxypropyl (HPBCD) and randomly methylated (RAMEB) β-cyclodextrin, we aimed to increase its biodisponibility and the effectiveness of the antifibrotic effects of chrysin at oral administration. Liver fibrosis in mice was induced in 7 weeks by CCl₄ i.p. administration, and afterwards treated with 50 mg/kg of CHR-HPBCD, CHR-RAMEB, and free chrysin. CCl₄ administration increased hepatic inflammation (which was augmented by the upregulation of nuclear factor kappa-light-chain enhancer of activated B cells (NF-kB), tumor necrosis factor (TNF)-α, and interleukin 6 (IL-6) and induced fibrosis, as determined using histopathology and electron microscopy. These results were also confirmed by the upregulation of Collagen I (Col I) and matrix metalloproteinase (MMP) expression, which led to extracellular fibrotic matrix proliferation. Moreover, the immunopositivity of alpha-smooth muscle actin (a-SMA) in the CCl₄ group was evidence of hepatic stellate cell (HSC) activation. The main profibrotic pathway was activated, as confirmed by an increase in the transforming growth factor- β1 (TGF-β1) and Smad 2/3 expression, while Smad 7 expression was decreased. Treatment with CHR–HPBCD and CHR–RAMEB considerably reduced liver injury, attenuated inflammation, and decreased extracellular liver collagen deposits. CHR–RAMEB was determined to be the most active antifibrotic complex. We conclude that both nanocomplexes exert anti-inflammatory effects and antifibrotic effects in a considerably stronger manner than for free chrysin administration.

Administration of Human MSC-Derived Extracellular Vesicles for the Treatment of Primary Sclerosing Cholangitis: Preclinical Data in MDR2 Knockout Mice

Primary Sclerosing Cholangitis (PSC) is a progressive liver disease for which there is no effective medical therapy. PSC belongs to the family of immune-mediated biliary disorders and it is characterized by persistent biliary inflammation and fibrosis. Here, we explored the possibility of using extracellular vesicles (EVs) derived from human, bone marrow mesenchymal stromal cells (MSCs) to target liver inflammation and reduce fibrosis in a mouse model of PSC. Five-week-old male FVB.129P2-Abcb4tm1Bor mice were intraperitoneally injected with either 100 µL of EVs (± 9.1 × 109 particles/mL) or PBS, once a week, for three consecutive weeks. One week after the last injection, mice were sacrificed and liver and blood collected for flow cytometry analysis and transaminase quantification. In FVB.129P2-Abcb4tm1Bor mice, EV administration resulted in reduced serum levels of alkaline phosphatase (ALP), bile acid (BA), and alanine aminotransferase (ALT), as well as in decreased liver fibrosis. Mechanistically, we observed that EVs reduce liver accumulation of both granulocytes and T cells and dampen VCAM-1 expression. Further analysis revealed that the therapeutic effect of EVs is accompanied by the inhibition of NFkB activation in proximity of the portal triad. Our pre-clinical experiments suggest that EVs isolated from MSCs may represent an effective therapeutic strategy to treat patients suffering from PSC.

Protective effect of herbal medicine Huangqi decoction against chronic cholestatic liver injury by inhibiting bile acid-stimulated inflammation in DDC-induced mice

BACKGROUND

Huangqi decoction (HQD), a classic traditional herbal medicine, has been used for liver fibrosis, but its effect on intrahepatic chronic cholestatic liver injury remains unknown.

PURPOSE

In the present study, we investigated the hepatoprotective effect of HQD and the underlying molecular mechanisms in 3, 5-diethoxycarbonyl-1, 4-dihydroxychollidine (DDC)-induced chronic cholestatic mice.

METHODS

The DDC-induced cholestatic mice were administrated HQD for 4 or 8 weeks. Serum biochemistry and morphology were investigated. The serum and liver bile acid (BA) levels were detected by ultra performance liquid chromatography-tandem mass spectrometry. The liver expression of BA metabolizing enzymes and transporters, and inflammatory and fibrotic markers was measured by real-time polymerase chain reaction, western blotting, and immunohistochemistry.

RESULTS

HQD treatment for 4 or 8 weeks ameliorated DDC-induced liver injury by improving impaired hepatic function and tissue damage. HQD treatment for 8 weeks further decreased the liver expression of cytokeratin 19, tumor growth factor (TGF)-β, collagen I, and α-smooth muscle actin, and ameliorated ductular reaction and liver fibrosis. HQD markedly decreased the accumulation of serum and liver BA. The expression of BA-metabolizing enzymes, cytochrome P450 2b10 and UDP glucuronosyltransferase 1 A1, and multidrug resistance-associated protein 2, Mrp3, and Mrp4 involved in BA homeostasis was increased by 4 weeks of HQD treatment. The expression of BA uptake transporter Na⁺-taurocholate cotransporting polypeptide was decreased and that of Mrp4 was increased after 8 weeks of HQD treatment. Nuclear factor-E2-related factor-2 (Nrf2) was remarkably induced by HQD treatment. Additionally, HQD treatment for 8 weeks decreased the liver expression of inflammatory factors, interleukin (IL)-6, IL-1β, tumor necrosis factor-α, monocyte chemoattractant protein-1, and intracellular adhesion molecule-1. HQD suppressed the nuclear factor (NF)-κB pathway.

CONCLUSION

HQD protected mice against chronic cholestatic liver injury and biliary fibrosis, which may be associated with the induction of the Nrf2 pathway and inhibition of the NF-κB pathway, ameliorating BA-stimulated inflammation.

Identification of clinical risk factors for histological progression of primary biliary cholangitis

AIM

To identify laboratory predictors of histological progression (HP) of primary biliary cholangitis (PBC).

METHODS

Sequential biopsies were carried out on 35 (11.4%) of 308 patients with PBC treated with ursodeoxycholic acid (UDCA). Patients were divided into high γ-glutamyl transpeptidase (GGT) (n = 18) and low GGT (n = 17) groups, based on the median value of GGT at baseline. Patients were then categorized as showing HP (progressive group, PG) or lacking HP (non-progressive group, NPG) according to the Scheuer and Nakanuma classifications, with the latter grading liver fibrosis (fibrosis score) and bile duct loss (BDL score).

RESULTS

According to the Scheuer definition, 12 patients had HP and 23 did not. According to the Nakanuma definition, 8 and 27 patients were in the PG and NPG groups, respectively. The fibrosis and BDL scores progressed in 13 and 8 patients, respectively, whereas 22 and 25 patients did not show HP, respectively. Fisher's exact probability test analysis revealed that the rate of HP using the Nakanuma fibrosis score was significantly higher in the high GGT group compared to the low GGT group (P < 0.05). However, no significant correlation was found between the HP of PBC and the biochemical response to UDCA therapy. Both univariate and multivariate logistic regression analyses indicated that the serum GGT level at baseline is an independent risk factor for an increased Nakanuma fibrosis score.

CONCLUSIONS

The level of serum GGT at baseline is significantly associated with liver fibrosis progression in PBC, and therefore could help to predict the HP of PBC.

Divergent expression of liver transforming growth factor superfamily cytokines after successful portoenterostomy in biliary atresia

BACKGROUND

Pathogenesis of progressive liver fibrosis in biliary atresia after successful portoenterostomy remains unclear. We related hepatic expression of transforming growth factor beta (TGF-β) superfamily cytokines to histologic liver injury after successful portoenterostomy.

METHODS

Enrolled in our study were 28 patients with biliary atresia who had liver biopsies obtained during and after successful portoenterostomy, which normalized serum bilirubin (<20 µmol/l). Biopsies were evaluated for cholestasis, inflammation, ductal reaction, and fibrosis and were stained immunohistochemically for transforming growth factor beta 1, transforming growth factor beta 2, connective tissue growth factor, and decorin. Respective gene expression (TGFB1, TGFB2, TGFB3, CTGF, DCN) was analyzed at follow-up using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Results were compared with fibrotic and healthy control livers.

RESULTS

After median follow-up of 3.0 years, histologic cholestasis resolved, whereas fibrosis had progressed only in isolated biliary atresia. Liver protein expression of transforming growth factor beta 1 and connective tissue growth factor (P < .001 for both), but not that of transforming growth factor beta 2 or decorin, decreased after successful portoenterostomy, although expression of all four cytokines remained elevated. In accordance with postportoenterostomy changes in protein expression, follow-up ribonucleic acid expression of TGFB2 and DCN, but not that of TGFB1 and CTGF, was upregulated when compared with the controls. Both protein and gene expression of transforming growth factor beta 1 and protein expression of transforming growth factor beta 2, connective tissue growth factor and decorin correlated with METAVIR fibrosis stage. Syndromic patients (n = 12) showed milder fibrosis and lower transforming growth factor beta 1 expression than patients with isolated biliary atresia.

CONCLUSION

These findings support a central role of transforming growth factor beta superfamily in mediating continuing liver fibrogenesis after successful portoenterostomy. Transforming growth factor beta pathway cytokines responded divergently to clearance of jaundice, which was reflected by differential progression of fibrosis between syndromic and isolated patients.

Ursodeoxycholate inhibits mast cell activation and reverses biliary injury and fibrosis in Mdr2-/- mice and human primary sclerosing cholangitis

Ursodeoxycholic acid (UDCA) is used to treat biliary disorders; and, bile acids alter mast cell (MC) histamine release. MCs infiltrate Mdr2^-/- mice liver (model of primary sclerosing cholangitis (PSC)). MC-derived histamine increases inflammation, hepatic stellate cell (HSC) activation and fibrosis. The objective was to determine the effects of UDCA treatment on MC infiltration, biliary damage, inflammation and fibrosis in Mdr2^-/- mice and human PSC. Wild-type and Mdr2^-/- mice were fed bile acid control diet or UDCA (0.5% wt/wt). Human samples were collected from control and PSC patients treated with placebo or UDCA (15 mg/kg/BW). MC infiltration was measured by immunhistochemistry and quantitative polymerase chain reaction (qPCR) for c-Kit, chymase, and tryptase. The HDC/histamine/histamine receptor (HR)-axis was evaluated by EIA and qPCR. Intrahepatic bile duct mass (IBDM) and biliary proliferation was evaluated by CK-19 and Ki-67 staining. Fibrosis was detected by immunostaining and qPCR for fibrotic markers. Inflammatory components were measured by qPCR. HSC activation was measured by SYP-9 staining. Inflammation was detected by qPCR for CD68. In vitro, MCs were treated with UDCA (40 μM) prior to HA secretion evaluation and coculturing with cholangiocytes or HSCs. BrDU incorporation and fibrosis by qPCR was performed. UDCA reduced MC number, the HDC/histamine/HR-axis, IBDM, HSC activation, inflammation, and fibrosis in Mdr2^-/- mice and PSC patients. In vitro, UDCA decreases MC-histamine release, which was restored by blocking ASBT and FXRβ. Proliferation and fibrosis decreased after treatment with UDCA-treated MCs. We conclude that UDCA acts on MCs reducing histamine levels and decreases the inflammatory/hyperplastic/fibrotic reaction seen in PSC. Ursodeoxycholic acid (UDCA) is used to treat biliary disorders; and, bile acids alter mast cell (MC) histamine release. Following liver injury like primary sclerosing cholangitis in mice and humans, MCs infiltrate. MC-derived histamine increases biliary damage, fibrosis, and inflammation. UDCA treatment decreases these parameters via reduced MC activation.

Liver fibrosis: Pathophysiology, pathogenetic targets and clinical issues

The progression of chronic liver diseases (CLD), irrespective of etiology, involves chronic parenchymal injury, persistent activation of inflammatory response as well as sustained activation of liver fibrogenesis and wound healing response. Liver fibrogenesis, is a dynamic, highly integrated molecular, cellular and tissue process responsible for driving the excess accumulation of extracellular matrix (ECM) components (i.e., liver fibrosis) sustained by an eterogeneous population of hepatic myofibroblasts (MFs). The process of liver fibrogenesis recognizes a number of common and etiology-independent mechanisms and events but it is also significantly influenced by the specific etiology, as also reflected by peculiar morphological patterns of liver fibrosis development. In this review we will analyze the most relevant established and/or emerging pathophysiological issues underlying CLD progression with a focus on the role of critical hepatic cell populations, mechanisms and signaling pathways involved, as they represent potential therapeutic targets, to finally analyze selected and relevant clinical issues.

Animal models of portal hypertension

Chronic liver diseases ultimately lead to cirrhosis and portal hypertension (PHT). Indeed, PHT is a major cause of severe complications, while medical treatment is limited to non-selective beta blockers. Sophisticated animal models are needed to investigate novel treatment options for different etiologies of liver disease, effective anti-fibrotic agents as well as vasoactive drugs against PHT. In this review, we present some of the most common animal models of liver disease and PHT - including pre-hepatic, intra-hepatic and post-hepatic PHT in rodents. Methodology for induction, considerations for disease etiology, advantages and limitations and practical issues of these animal models are discussed. The appropriate and sensible use of animal models in preclinical research supporting the 3R concept of replacement, reduction and refinement is highlighted.

The soluble guanylate cyclase stimulator riociguat reduces fibrogenesis and portal pressure in cirrhotic rats

In cirrhotic patients, portal hypertension (PHT) deteriorates survival, yet treatment options are limited. A major contributor to increased intrahepatic vasoconstriction in PHT is dysfunctional nitric-oxide signaling. Soluble guanylate cyclase (sGC) is the receptor of nitric-oxide and can be stimulated by riociguat. Riociguat is approved for pulmonary hypertension but has not been studied in liver cirrhosis. In this study we assessed the effects of riociguat on PHT and liver fibrosis in cholestatic (bile duct ligation, BDL) and toxic (carbon-tetrachloride, CCl4) rat models. In cirrhotic livers sGC expression was upregulated. In BDL rats, riociguat reduced liver fibrosis and decreased portal pressure without affecting systemic hemodynamics. In an early BDL disease stage, riociguat decreased bile duct proliferation, improved sinusoidal vascular dysfunction and inhibited angiogenesis. In advanced BDL riociguat exhibited anti-inflammatory effects. In CCl4 rats the beneficial effects of riociguat treatment were less pronounced and confined to an early disease stage. Similarly, in patients with cholestatic cirrhosis and PHT nitrates (that induce sGC activity) decreased portal pressure more effectively than in patients with non-cholestatic etiology. We also found an improvement of transaminases in patients with pulmonary hypertension receiving riociguat. Our findings support the clinical development of sGC stimulators in patients with cirrhotic PHT.

Junctional adhesion molecules JAM-B and JAM-C promote autoimmune-mediated liver fibrosis in mice

Fibrosis remains a serious health concern in patients with chronic liver disease. We recently reported that chemically induced chronic murine liver injury triggers increased expression of junctional adhesion molecules (JAMs) JAM-B and JAM-C by endothelial cells and de novo synthesis of JAM-C by hepatic stellate cells (HSCs). Here, we demonstrate that biopsies of patients suffering from primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC) or autoimmune hepatitis (AIH) display elevated levels of JAM-C on portal fibroblasts (PFs), HSCs, endothelial cells and cholangiocytes, whereas smooth muscle cells expressed JAM-C constitutively. Therefore, localization and function of JAM-B and JAM-C were investigated in three mouse models of autoimmune-driven liver inflammation. A PBC-like disease was induced by immunization with 2-octynoic acid-BSA conjugate, which resulted in the upregulation of both JAMs in fibrotic portal triads. Analysis of a murine model of PSC revealed a role of JAM-C in PF cell-cell adhesion and contractility. In mice suffering from AIH, endothelial cells increased JAM-B level and HSCs and capsular fibroblasts became JAM-C-positive. Most importantly, AIH-mediated liver fibrosis was reduced in JAM-B^-/- mice or when JAM-C was blocked by soluble recombinant JAM-C. Interestingly, loss of JAM-B/JAM-C function had no effect on leukocyte infiltration, suggesting that the well-documented function of JAMs in leukocyte recruitment to inflamed tissue was not effective in the tested chronic models. This might be different in patients and may even be complicated by the fact that human leukocytes express JAM-C. Our findings delineate JAM-C as a mediator of myofibroblast-operated contraction of the liver capsule, intrahepatic vasoconstriction and bile duct stricture. Due to its potential to interact heterophilically with endothelial JAM-B, JAM-C supports also HSC/PF mural cell function. Together, these properties allow JAM-B and JAM-C to actively participate in vascular remodeling associated with liver/biliary fibrosis and suggest them as valuable targets for anti-fibrosis therapies.

Vitamin D and the Liver-Correlation or Cause?

Vitamin D is becoming increasingly accepted as an important physiological regulator outside of its classical role in skeletal homeostasis. A growing body of evidence connects vitamin D with hepatic disease. This review summarises the role of vitamin D in liver homeostasis and disease and discusses the therapeutic potential of vitamin D-based treatments to protect against hepatic disease progression and to improve response to treatment. While pre-clinical experimental data is promising, clinical trials around liver diseases have mostly been under-powered, and further studies will be required to clarify whether vitamin D or vitamin D analogues have beneficial effects on liver disease.

Hepatic Parenchymal Injury in Crigler-Najjar Type I

BACKGROUND

Crigler-Najjar syndrome type I (CNI) arises from biallelic variants of UGT1A1 that abrogate uridine diphosphate glucuronosyltransferase (UGT1A1) activity resulting in unconjugated hyperbilirubinemia. Historically, liver parenchyma in CNI was considered structurally and histologically normal. Recent review of CNI liver explants revealed fibrosis. Our aim was to investigate the association between hepatic histology and disease phenotype in CNI.

METHODS

We extracted data from the medical record at the time of liver transplant from 22 patients with CNI at the Children's Hospital of Pittsburgh, and reviewed explant histology. Continuous data were normally distributed, are presented as mean (±1 SD), and analyzed using two-tailed Student t-test. Categorical data were analyzed using the Chi-square test.

RESULTS

Both alanine transaminase (ALT; mean 87.4 IU/L) and aspartate transaminase (AST; mean 54.6 IU/L) were elevated. Nine (41%) of 22 explants had significant fibrosis. Pericentral (n = 5), periportal (n = 2), and mixed (n = 2) patterns of fibrosis occurred. A significant difference in mean age of subjects with fibrotic versus non-fibrotic livers (16.1 years vs 10.5 years; P = 0.02) was seen. There were no indices of synthetic liver dysfunction or portal hypertension. Neither a history of gallstone disease nor excess weight appeared to contribute to the development of fibrosis.

CONCLUSIONS

For the first time, we report a 41% prevalence of clinically silent, yet histologically significant fibrosis among subjects with Crigler-Najjar type 1. Risk for fibrosis appears to accrue with time, indicating that earlier intervention may be prudent whenever considering alternative treatments such as hepatocyte transplant, auxiliary liver transplant, or viral gene therapy.

Pathophysiology of liver fibrosis and the methodological barriers to the development of anti-fibrogenic agents

Liver fibrosis and cirrhosis resulting from long-standing liver damage represents a major health care burden worldwide. To date, there is no anti-fibrogenic agent available, making liver transplantation the only curative treatment for decompensated cirrhotic liver disease. Liver fibrosis can result from different underlying chronic liver disease, such as chronic viral infection, excessive alcohol consumption, fatty liver disease or autoimmune liver diseases. It is becoming increasingly recognised that as a result from different pathogenic mechanisms liver fibrosis must be considered as many different diseases for which individual treatment strategies need to be developed. Moreover, the pathogenic changes of both liver architecture and vascularisation in cirrhotic livers, as well as the lack of "true-to-life" in vitro models have impeded the development of an effective anti-fibrogenic drug. Thus, in order to identify an efficient anti-fibrogenic compound, novel in-vitro models mimicking the interplay between pro-fibrogenic cell populations, immune cells and, importantly, the extracellular matrix need to be developed.

Can a fibrotic liver afford epithelial-mesenchymal transition?

The question whether epithelial-mesenchymal transition (EMT) occurs during liver fibrogenesis is a controversial issue. In vitro studies confirm that hepatocytes or cholangiocytes undergo EMT upon transforming growth factor β (TGF-β) stimulation, whereas in vivo experiments based on genetic fate mapping of specific cell populations suggest that EMT does not occur in fibrotic animal models. In this review we present current data supporting or opposing EMT in chronic liver disease and discuss conditions for the occurrence of EMT in patients. Based on the available data and our clinical observations we hypothesize that EMT-like alterations in liver cirrhosis are a side effect of high levels of TGF-β and other pro-fibrotic mediators rather than a biological process converting functional parenchyma, i.e., hepatocytes, into myofibroblasts at a time when essential liver functions are deteriorating.

Bile duct ligation-induced biliary hyperplasia, hepatic injury, and fibrosis are reduced in mast cell-deficient KitW-sh mice

Activated mast cells (MCs) release histamine (HA) and MCs infiltrate the liver following bile duct ligation (BDL), increasing intrahepatic bile duct mass (IBDM) and fibrosis. We evaluated the effects of BDL in MC-deficient (Kit^W-sh ) mice. Wild-type (WT) and Kit^W-sh mice were subjected to sham or BDL for up to 7 days and Kit^W-sh mice were injected with cultured mast cells or 1× phosphate-buffered saline (PBS) before collecting serum, liver, and cholangiocytes. Liver damage was assessed by hematoxylin and eosin and alanine aminotransferase levels. IBDM was detected by cytokeratin-19 expression and proliferation by Ki-67 immunohistochemistry (IHC). Fibrosis was detected by IHC, hydroxyproline content, and by qPCR for fibrotic markers. Hepatic stellate cell (HSC) activation and transforming growth factor-beta 1 (TGF-β1) expression/secretion were evaluated. Histidine decarboxylase (HDC) and histamine receptor (HR) expression were detected by qPCR and HA secretion by enzymatic immunoassay. To evaluate vascular cells, von Willebrand factor (vWF) and vascular endothelial growth factor (VEGF)-C expression were measured. In vitro, cultured HSCs were stimulated with cholangiocyte supernatants and alpha-smooth muscle actin levels were measured. BDL-induced liver damage was reduced in BDL Kit^W-sh mice, whereas injection of MCs did not mimic BDL-induced damage. In BDL Kit^W-sh mice, IBDM, proliferation, HSC activation/fibrosis, and TGF-β1 expression/secretion were decreased. The HDC/HA/HR axis was ablated in sham and BDL Kit^W-sh mice. vWF and VEGF-C expression decreased in BDL Kit^W-sh mice. In Kit^W-sh mice injected with MCs, IBDM, proliferation, fibrosis, and vascular cell activation increased. Stimulation with cholangiocyte supernatants from BDL WT or Kit^W-sh mice injected with MCs increased HSC activation, which decreased with supernatants from BDL Kit^W-sh mice.

CONCLUSION

MCs promote hyperplasia, fibrosis, and vascular cell activation. Knockout of MCs decreases BDL-induced damage. Modulation of MCs may be important in developing therapeutics for cholangiopathies. (Hepatology 2017;65:1991-2004).

Regulators of Cholangiocyte Proliferation

Cholangiocytes, a small population of cells within the normal liver, have been the focus of a significant amount of research over the past two decades because of their involvement in cholangiopathies such as primary sclerosing cholangitis and primary biliary cholangitis. This article summarizes landmark studies in the field of cholangiocyte physiology and aims to provide an updated review of biliary pathogenesis. The historical approach of rodent extrahepatic bile duct ligation and the relatively recent utilization of transgenic mice have led to significant discoveries in cholangiocyte pathophysiology. Cholangiocyte physiology is a complex system based on heterogeneity within the biliary tree and a number of signaling pathways that serve to regulate bile composition. Studies have expanded the list of neuropeptides, neurotransmitters, and hormones that have been shown to be key regulators of proliferation and biliary damage. The peptide histamine and hormones, such as melatonin and angiotensin, angiotensin, as well as numerous sex hormones, have been implicated in cholangiocyte proliferation during cholestasis. Numerous pathways promote cholangiocyte proliferation during cholestasis, and there is growing evidence to suggest that cholangiocyte proliferation may promote hepatic fibrosis. These pathways may represent significant therapeutic potential for a subset of cholestatic liver diseases that currently lack effective therapies.

Cirrhosis and autoimmune liver disease: Current understanding

Primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC) and autoimmune hepatitis (AIH) constitute the classic autoimmune liver diseases (AILDs). While AIH target the hepatocytes, in PBC and PSC the targets of the autoimmune attack are the biliary epithelial cells. Persistent liver injury, associated with chronic AILD, leads to un-resolving inflammation, cell proliferation and the deposition of extracellular matrix proteins by hepatic stellate cells and portal myofibroblasts. Liver cirrhosis, and the resultant loss of normal liver function, inevitably ensues. Patients with cirrhosis have higher risks or morbidity and mortality, and that in the decompensated phase, complications of portal hypertension and/or liver dysfunction lead to rapid deterioration. Accurate diagnosis and monitoring of cirrhosis is, therefore of upmost importance. Liver biopsy is currently the gold standard technique, but highly promising non-invasive methodology is under development. Liver transplantation (LT) is an effective therapeutic option for the management of end-stage liver disease secondary to AIH, PBC and PSC. LT is indicated for AILD patients who have progressed to end-stage chronic liver disease or developed intractable symptoms or hepatic malignancy; in addition, LT may also be indicated for patients presenting with acute liver disease due to AIH who do not respond to steroids.

Inhibition of mast cell-secreted histamine decreases biliary proliferation and fibrosis in primary sclerosing cholangitis Mdr2(-/-) mice

Hepatic fibrosis is marked by activation of hepatic stellate cells (HSCs). Cholestatic injury precedes liver fibrosis, and cholangiocytes interact with HSCs promoting fibrosis. Mast cells (MCs) infiltrate following liver injury and release histamine, increasing biliary proliferation. We evaluated if inhibition of MC-derived histamine decreases biliary proliferation and fibrosis. Wild-type and multidrug resistance 2 knockout mice (9-11 weeks) were treated with cromolyn sodium for 1 week to block MC-derived histamine. Biliary mass and proliferation were evaluated by immunohistochemistry for cytokeratin 19 and Ki-67. Bile flow, bicarbonate excretion, and total bile acids were measured in all mice. Fibrosis was evaluated by sirius red/fast green staining and by quantitative polymerase chain reaction for alpha-smooth muscle actin, fibronectin, collagen type 1a, and transforming growth factor-beta 1. HSC activation was evaluated by quantitative polymerase chain reaction in total liver and immunofluorescent staining in tissues for synaptophysin 9. Histamine serum secretion was measured by enzymatic immunoassay. Mouse liver and human liver samples from control or primary sclerosing cholangitis patients were evaluated for MC markers by quantitative polymerase chain reaction and immunohistochemistry. In vitro, cultured MCs were transfected with histidine decarboxylase short hairpin RNA to decrease histamine secretion and subsequently cocultured with cholangiocytes or HSCs prior to measuring fibrosis markers, proliferation, and transforming growth factor-beta 1 secretion. Treatment with cromolyn sodium decreased biliary proliferation, fibrosis, histamine secretion, and bile flow in multidrug resistance 2 knockout mice. Primary sclerosing cholangitis mice and patients have increased MCs. Knockdown of MC histidine decarboxylase decreased cholangiocyte and HSC proliferation/activation.

CONCLUSION

MCs are recruited to proliferating cholangiocytes and promote fibrosis. Inhibition of MC-derived histamine decreases fibrosis, and regulation of MC mediators may be therapeutic for primary sclerosing cholangitis. (Hepatology 2016;64:1202-1216).

The secretin/secretin receptor axis modulates liver fibrosis through changes in transforming growth factor-β1 biliary secretion in mice

The secretin/secretin receptor (SR) axis is up-regulated by proliferating cholangiocytes during cholestasis. Secretin stimulates biliary proliferation by down-regulation of let-7a and subsequent up-regulation of the growth-promoting factor, nerve growth factor (NGF). It is not known whether the secretin/SR axis plays a role in subepithelial fibrosis observed during cholestasis. Our aim was to determine the role of the secretin/SR axis in activation of biliary fibrosis in animal models and human primary sclerosing cholangitis (PSC). Studies were performed in wild-type (WT) mice with bile duct ligation (BDL), BDL SR(-/-) mice, or Mdr2(-/-) mouse models of cholestatic liver injury. In selected studies, the SR antagonist (Sec 5-27) was used to block the secretin/SR axis. Biliary proliferation and fibrosis were evaluated as well as secretion of secretin (by cholangiocytes and S cells), expression of markers of fibrosis, transforming growth factor-β1 (TGF-β1), transforming growth factor-β1 receptor (TGF-β1R), let-7a, and downstream expression of NGF. Correlative studies were performed in human control and PSC liver tissue biopsies, serum, and bile. SR antagonist reduced biliary proliferation and hepatic fibrosis in BDL WT and Mdr2(-/-) mice. There was decreased expression of let-7a in BDL and Mdr2(-/-) cholangiocytes that was associated with increased NGF expression. Inhibition of let-7a accelerated liver fibrosis was attributed to cholestasis. There was increased expression of TGF-β1 and TGF-β1R. Significantly higher expression of secretin, SR, and TGF-β1 was observed in PSC patient liver samples compared to healthy controls. In addition, there was higher expression of fibrosis genes and remarkably decreased expression of let-7a and increased expression of NGF compared to the control.

CONCLUSION

The secretin/SR axis plays a key role in regulating the biliary contribution to cholestasis-induced hepatic fibrosis. (Hepatology 2016;64:865-879).

Detection of Autoantibodies to Vascular Endothelial Growth Factor Receptor-3 in Bile Duct Ligated Rats and Correlations with a Panel of Traditional Markers of Liver Diseases

There is a need for new noninvasive biomarkers (NIBMs) able to assess cholestasis and fibrosis in chronic cholestatic liver diseases (CCLDs). Tumorigenesis can arise from CCLDs. Therefore, autoantibodies to tumor-associated antigens (TAA) may be early produced in response to abnormal self-antigen expression caused by cholestatic injury. Vascular endothelial growth factor receptor-3 (VEGFR-3) has TAA potential since it is involved in cholangiocytes and lymphatic vessels proliferations during CCLDs. This study aims to detect autoantibodies directed at VEGFR-3 during bile duct ligation- (BDL-) induced cholestatic injury in rat sera and investigate whether they could be associated with traditional markers of liver damage, cholestasis, and fibrosis. An ELISA was performed to detect anti-VEGFR-3 autoantibodies in sera of rats with different degree of liver injury and results were correlated with aminotransferases, total bilirubin, and the relative fibrotic area. Mean absorbances of anti-VEGFR-3 autoantibodies were significantly increased from week one to week five after BDL. The highest correlation was observed with total bilirubin (R (2) = 0.8450, P = 3.04e - 12). In conclusion, anti-VEGFR-3 autoantibodies are early produced during BDL-induced cholestatic injury, and they are closely related to cholestasis, suggesting the potential of anti-VEGFR-3 autoantibodies as NIBMs of cholestasis in CCLDs and justifying the need for further investigations in patients with CCLD.

Inhibition of intestinal bile acid absorption improves cholestatic liver and bile duct injury in a mouse model of sclerosing cholangitis

BACKGROUND AND AIMS

Approximately 95% of bile acids (BAs) excreted into bile are reabsorbed in the gut and circulate back to the liver for further biliary secretion. Therefore, pharmacological inhibition of the ileal apical sodium-dependent BA transporter (ASBT/SLC10A2) may protect against BA-mediated cholestatic liver and bile duct injury.

METHODS

Eight week old Mdr2(-/-) (Abcb4(-/-)) mice (model of cholestatic liver injury and sclerosing cholangitis) received either a diet supplemented with A4250 (0.01% w/w) - a highly potent and selective ASBT inhibitor - or a chow diet. Liver injury was assessed biochemically and histologically after 4weeks of A4250 treatment. Expression profiles of genes involved in BA homeostasis, inflammation and fibrosis were assessed via RT-PCR from liver and ileum homogenates. Intestinal inflammation was assessed by RNA expression profiling and immunohistochemistry. Bile flow and composition, as well as biliary and fecal BA profiles were analyzed after 1week of ASBT inhibitor feeding.

RESULTS

A4250 improved sclerosing cholangitis in Mdr2(-/-) mice and significantly reduced serum alanine aminotransferase, alkaline phosphatase and BAs levels, hepatic expression of pro-inflammatory (Tnf-α, Vcam1, Mcp-1) and pro-fibrogenic (Col1a1, Col1a2) genes and bile duct proliferation (mRNA and immunohistochemistry for cytokeratin 19 (CK19)). Furthermore, A4250 significantly reduced bile flow and biliary BA output, which correlated with reduced Bsep transcription, while Ntcp and Cyp7a1 were induced. Importantly A4250 significantly reduced biliary BA secretion but preserved HCO3(-) and biliary phospholipid secretion resulting in an increased HCO3(-)/BA and PL/BA ratio. In addition, A4250 profoundly increased fecal BA excretion without causing diarrhea and altered BA pool composition, resulting in diminished concentrations of primary BAs tauro-β-muricholic acid and taurocholic acid.

CONCLUSIONS

Pharmacological ASBT inhibition attenuates cholestatic liver and bile duct injury by reducing biliary BA concentrations in mice.

Na(+) /H(+) exchanger regulatory factor 1 knockout mice have an attenuated hepatic inflammatory response and are protected from cholestatic liver injury

The intercellular adhesion molecule 1 (ICAM-1) is induced in mouse liver after bile duct ligation (BDL) and plays a key role in neutrophil-mediated liver injury in BDL mice. ICAM-1 has been shown to interact with cytoskeletal ezrin-radixin-moesin (ERM) proteins that also interact with the PDZ protein, Na(+) /H(+) exchanger regulatory factor 1 (NHERF-1/EBP50). In NHERF-1(-/-) mice, ERM proteins are significantly reduced in brush-border membranes from kidney and small intestine. ERM knockdown reduces ICAM-1 expression in response to tumor necrosis factor alpha. Here we show that NHERF-1 assembles ERM proteins, ICAM-1 and F-actin into a macromolecule complex that is increased in mouse liver after BDL. Compared to wild-type (WT) mice, both sham-operated and BDL NHERF-1(-/-) mice have lower levels of activated ERM and ICAM-1 protein in the liver accompanied by significantly reduced hepatic neutrophil accumulation, serum alanine aminotransferase, and attenuated liver injury after BDL. However, total bile acid concentrations in serum and liver of sham and BDL NHERF-1(-/-) mice were not significantly different from WT controls, although hepatic tetrahydroxylated bile acids and Cyp3a11 messenger RNA levels were higher in NHERF-1(-/-) BDL mice.

CONCLUSION

NHERF-1 participates in the inflammatory response that is associated with BDL-induced liver injury. Deletion of NHERF-1 in mice leads to disruption of the formation of ICAM-1/ERM/NHERF-1 complex and reduction of hepatic ERM proteins and ICAM-1, molecules that are up-regulated and are essential for neutrophil-mediated liver injury in cholestasis. Further study of the role of NHERF-1 in the inflammatory response in cholestasis and other forms of liver injury should lead to discovery of new therapeutic targets in hepatic inflammatory diseases.

Effects of Melittin Treatment in Cholangitis and Biliary Fibrosis in a Model of Xenobiotic-Induced Cholestasis in Mice

Cholangiopathy is a chronic immune-mediated disease of the liver, which is characterized by cholangitis, ductular reaction and biliary-type hepatic fibrosis. There is no proven medical therapy that changes the course of the disease. In previous studies, melittin was known for attenuation of hepatic injury, inflammation and hepatic fibrosis. This study investigated whether melittin provides inhibition on cholangitis and biliary fibrosis in vivo. Feeding 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) to mice is a well-established animal model to study cholangitis and biliary fibrosis. To investigate the effects of melittin on cholangiopathy, mice were fed with a 0.1% DDC-containing diet with or without melittin treatment for four weeks. Liver morphology, serum markers of liver injury, cholestasis markers for inflammation of liver, the degree of ductular reaction and the degree of liver fibrosis were compared between with or without melittin treatment DDC-fed mice. DDC feeding led to increased serum markers of hepatic injury, ductular reaction, induction of pro-inflammatory cytokines and biliary fibrosis. Interestingly, melittin treatment attenuated hepatic function markers, ductular reaction, the reactive phenotype of cholangiocytes and cholangitis and biliary fibrosis. Our data suggest that melittin treatment can be protective against chronic cholestatic disease in DDC-fed mice. Further studies on the anti-inflammatory capacity of melittin are warranted for targeted therapy in cholangiopathy.

Endoscopic ultrasound versus magnetic resonance cholangiopancreatography for common bile duct stones

BACKGROUND

Endoscopic ultrasound (EUS) and magnetic resonance cholangiopancreatography (MRCP) are tests used in the diagnosis of common bile duct stones in patients suspected of having common bile duct stones prior to undergoing invasive treatment. There has been no systematic review of the accuracy of EUS and MRCP in the diagnosis of common bile duct stones using appropriate reference standards.

OBJECTIVES

To determine and compare the accuracy of EUS and MRCP for the diagnosis of common bile duct stones.

SEARCH METHODS

We searched MEDLINE, EMBASE, Science Citation Index Expanded, BIOSIS, and Clinicaltrials.gov until September 2012. We searched the references of included studies to identify further studies and of systematic reviews identified from various databases (Database of Abstracts of Reviews of Effects (DARE), Health Technology Assessment (HTA), Medion, and ARIF (Aggressive Research Intelligence Facility)). We did not restrict studies based on language or publication status, or whether data were collected prospectively or retrospectively.

SELECTION CRITERIA

We included studies that provided the number of true positives, false positives, false negatives, and true negatives for EUS or MRCP. We only accepted studies that confirmed the presence of common bile duct stones by extraction of the stones (irrespective of whether this was done by surgical or endoscopic methods) for a positive test, and absence of common bile duct stones by surgical or endoscopic negative exploration of the common bile duct or symptom free follow-up for at least six months for a negative test, as the reference standard in people suspected of having common bile duct stones. We included participants with or without prior diagnosis of cholelithiasis; with or without symptoms and complications of common bile duct stones, with or without prior treatment for common bile duct stones; and before or after cholecystectomy. At least two authors independently screened abstracts and selected studies for inclusion.

DATA COLLECTION AND ANALYSIS

Two authors independently collected the data from each study. We used the bivariate model to obtain pooled estimates of sensitivity and specificity.

MAIN RESULTS

We included a total of 18 studies involving 2366 participants (976 participants with common bile duct stones and 1390 participants without common bile duct stones). Eleven studies evaluated EUS alone, and five studies evaluated MRCP alone. Two studies evaluated both tests. Most studies included patients who were suspected of having common bile duct stones based on abnormal liver function tests; abnormal transabdominal ultrasound; symptoms such as obstructive jaundice, cholangitis, or pancreatitis; or a combination of the above. The proportion of participants who had undergone cholecystectomy varied across studies. Not one of the studies was of high methodological quality. For EUS, the sensitivities ranged between 0.75 and 1.00 and the specificities ranged between 0.85 and 1.00. The summary sensitivity (95% confidence interval (CI)) and specificity (95% CI) of the 13 studies that evaluated EUS (1537 participants; 686 cases and 851 participants without common bile duct stones) were 0.95 (95% CI 0.91 to 0.97) and 0.97 (95% CI 0.94 to 0.99). For MRCP, the sensitivities ranged between 0.77 and 1.00 and the specificities ranged between 0.73 and 0.99. The summary sensitivity and specificity of the seven studies that evaluated MRCP (996 participants; 361 cases and 635 participants without common bile duct stones) were 0.93 (95% CI 0.87 to 0.96) and 0.96 (95% CI 0.90 to 0.98). There was no evidence of a difference in sensitivity or specificity between EUS and MRCP (P value = 0.5). From the included studies, at the median pre-test probability of common bile duct stones of 41% the post-test probabilities (with 95% CI) associated with positive and negative EUS test results were 0.96 (95% CI 0.92 to 0.98) and 0.03 (95% CI 0.02 to 0.06). At the same pre-test probability, the post-test probabilities associated with positive and negative MRCP test results were 0.94 (95% CI 0.87 to 0.97) and 0.05 (95% CI 0.03 to 0.09).

AUTHORS' CONCLUSIONS

Both EUS and MRCP have high diagnostic accuracy for detection of common bile duct stones. People with positive EUS or MRCP should undergo endoscopic or surgical extraction of common bile duct stones and those with negative EUS or MRCP do not need further invasive tests. However, if the symptoms persist, further investigations will be indicated. The two tests are similar in terms of diagnostic accuracy and the choice of which test to use will be informed by availability and contra-indications to each test. However, it should be noted that the results are based on studies of poor methodological quality and so the results should be interpreted with caution. Further studies that are of high methodological quality are necessary to determine the diagnostic accuracy of EUS and MRCP for the diagnosis of common bile duct stones.

Ultrasound versus liver function tests for diagnosis of common bile duct stones

BACKGROUND

Ultrasound and liver function tests (serum bilirubin and serum alkaline phosphatase) are used as screening tests for the diagnosis of common bile duct stones in people suspected of having common bile duct stones. There has been no systematic review of the diagnostic accuracy of ultrasound and liver function tests.

OBJECTIVES

To determine and compare the accuracy of ultrasound versus liver function tests for the diagnosis of common bile duct stones.

SEARCH METHODS

We searched MEDLINE, EMBASE, Science Citation Index Expanded, BIOSIS, and Clinicaltrials.gov to September 2012. We searched the references of included studies to identify further studies and systematic reviews identified from various databases (Database of Abstracts of Reviews of Effects, Health Technology Assessment, Medion, and ARIF (Aggressive Research Intelligence Facility)). We did not restrict studies based on language or publication status, or whether data were collected prospectively or retrospectively.

SELECTION CRITERIA

We included studies that provided the number of true positives, false positives, false negatives, and true negatives for ultrasound, serum bilirubin, or serum alkaline phosphatase. We only accepted studies that confirmed the presence of common bile duct stones by extraction of the stones (irrespective of whether this was done by surgical or endoscopic methods) for a positive test result, and absence of common bile duct stones by surgical or endoscopic negative exploration of the common bile duct, or symptom-free follow-up for at least six months for a negative test result as the reference standard in people suspected of having common bile duct stones. We included participants with or without prior diagnosis of cholelithiasis; with or without symptoms and complications of common bile duct stones, with or without prior treatment for common bile duct stones; and before or after cholecystectomy. At least two authors screened abstracts and selected studies for inclusion independently.

DATA COLLECTION AND ANALYSIS

Two authors independently collected data from each study. Where meta-analysis was possible, we used the bivariate model to summarise sensitivity and specificity.

MAIN RESULTS

Five studies including 523 participants reported the diagnostic accuracy of ultrasound. One studies (262 participants) compared the accuracy of ultrasound, serum bilirubin and serum alkaline phosphatase in the same participants. All the studies included people with symptoms. One study included only participants without previous cholecystectomy but this information was not available from the remaining studies. All the studies were of poor methodological quality. The sensitivities for ultrasound ranged from 0.32 to 1.00, and the specificities ranged from 0.77 to 0.97. The summary sensitivity was 0.73 (95% CI 0.44 to 0.90) and the specificity was 0.91 (95% CI 0.84 to 0.95). At the median pre-test probability of common bile duct stones of 0.408, the post-test probability (95% CI) associated with positive ultrasound tests was 0.85 (95% CI 0.75 to 0.91), and negative ultrasound tests was 0.17 (95% CI 0.08 to 0.33).The single study of liver function tests reported diagnostic accuracy at two cut-offs for bilirubin (greater than 22.23 μmol/L and greater than twice the normal limit) and two cut-offs for alkaline phosphatase (greater than 125 IU/L and greater than twice the normal limit). This study also assessed ultrasound and reported higher sensitivities for bilirubin and alkaline phosphatase at both cut-offs but the specificities of the markers were higher at only the greater than twice the normal limit cut-off. The sensitivity for ultrasound was 0.32 (95% CI 0.15 to 0.54), bilirubin (cut-off greater than 22.23 μmol/L) was 0.84 (95% CI 0.64 to 0.95), and alkaline phosphatase (cut-off greater than 125 IU/L) was 0.92 (95% CI 0.74 to 0.99). The specificity for ultrasound was 0.95 (95% CI 0.91 to 0.97), bilirubin (cut-off greater than 22.23 μmol/L) was 0.91 (95% CI 0.86 to 0.94), and alkaline phosphatase (cut-off greater than 125 IU/L) was 0.79 (95% CI 0.74 to 0.84). No study reported the diagnostic accuracy of a combination of bilirubin and alkaline phosphatase, or combinations with ultrasound.

AUTHORS' CONCLUSIONS

Many people may have common bile duct stones in spite of having a negative ultrasound or liver function test. Such people may have to be re-tested with other modalities if the clinical suspicion of common bile duct stones is very high because of their symptoms. False-positive results are also possible and further non-invasive testing is recommended to confirm common bile duct stones to avoid the risks of invasive testing.It should be noted that these results were based on few studies of poor methodological quality and the results for ultrasound varied considerably between studies. Therefore, the results should be interpreted with caution. Further studies of high methodological quality are necessary to determine the diagnostic accuracy of ultrasound and liver function tests.

Endoscopic retrograde cholangiopancreatography versus intraoperative cholangiography for diagnosis of common bile duct stones

BACKGROUND

Endoscopic retrograde cholangiopancreatography (ERCP) and intraoperative cholangiography (IOC) are tests used in the diagnosis of common bile duct stones in people suspected of having common bile duct stones. There has been no systematic review of the diagnostic accuracy of ERCP and IOC.

OBJECTIVES

To determine and compare the accuracy of ERCP and IOC for the diagnosis of common bile duct stones.

SEARCH METHODS

We searched MEDLINE, EMBASE, Science Citation Index Expanded, BIOSIS, and Clinicaltrials.gov to September 2012. To identify additional studies, we searched the references of included studies and systematic reviews identified from various databases (Database of Abstracts of Reviews of Effects (DARE)), Health Technology Assessment (HTA), Medion, and ARIF (Aggressive Research Intelligence Facility)). We did not restrict studies based on language or publication status, or whether data were collected prospectively or retrospectively.

SELECTION CRITERIA

We included studies that provided the number of true positives, false positives, false negatives, and true negatives for ERCP or IOC. We only accepted studies that confirmed the presence of common bile duct stones by extraction of the stones (irrespective of whether this was done by surgical or endoscopic methods) for a positive test, and absence of common bile duct stones by surgical or endoscopic negative exploration of the common bile duct, or symptom-free follow-up for at least six months for a negative test as the reference standard in people suspected of having common bile duct stones. We included participants with or without prior diagnosis of cholelithiasis; with or without symptoms and complications of common bile duct stones; with or without prior treatment for common bile duct stones; and before or after cholecystectomy. At least two authors screened abstracts and selected studies for inclusion independently.

DATA COLLECTION AND ANALYSIS

Two authors independently collected data from each study. We used the bivariate model to summarise the sensitivity and specificity of the tests.

MAIN RESULTS

We identified five studies including 318 participants (180 participants with and 138 participants without common bile duct stones) that reported the diagnostic accuracy of ERCP and five studies including 654 participants (125 participants with and 529 participants without common bile duct stones) that reported the diagnostic accuracy of IOC. Most studies included people with symptoms (participants with jaundice or pancreatitis) suspected of having common bile duct stones based on blood tests, ultrasound, or both, prior to the performance of ERCP or IOC. Most studies included participants who had not previously undergone removal of the gallbladder (cholecystectomy). None of the included studies was of high methodological quality as evaluated by the QUADAS-2 tool (quality assessment tool for diagnostic accuracy studies). The sensitivities of ERCP ranged between 0.67 and 0.94 and the specificities ranged between 0.92 and 1.00. For ERCP, the summary sensitivity was 0.83 (95% confidence interval (CI) 0.72 to 0.90) and specificity was 0.99 (95% CI 0.94 to 1.00). The sensitivities of IOC ranged between 0.75 and 1.00 and the specificities ranged between 0.96 and 1.00. For IOC, the summary sensitivity was 0.99 (95% CI 0.83 to 1.00) and specificity was 0.99 (95% CI 0.95 to 1.00). For ERCP, at the median pre-test probability of common bile duct stones of 0.35 estimated from the included studies (i.e., 35% of people suspected of having common bile duct stones were confirmed to have gallstones by the reference standard), the post-test probabilities associated with positive test results was 0.97 (95% CI 0.88 to 0.99) and negative test results was 0.09 (95% CI 0.05 to 0.14). For IOC, at the median pre-test probability of common bile duct stones of 0.35, the post-test probabilities associated with positive test results was 0.98 (95% CI 0.85 to 1.00) and negative test results was 0.01 (95% CI 0.00 to 0.10). There was weak evidence of a difference in sensitivity (P value = 0.05) with IOC showing higher sensitivity than ERCP. There was no evidence of a difference in specificity (P value = 0.7) with both tests having similar specificity.

AUTHORS' CONCLUSIONS

Although the sensitivity of IOC appeared to be better than that of ERCP, this finding may be unreliable because none of the studies compared both tests in the same study populations and most of the studies were methodologically flawed. It appears that both tests were fairly accurate in guiding further invasive treatment as most people diagnosed with common bile duct stones by these tests had common bile duct stones. Some people may have common bile duct stones in spite of having a negative ERCP or IOC result. Such people may have to be re-tested if the clinical suspicion of common bile duct stones is very high because of their symptoms or persistently abnormal liver function tests. However, the results should be interpreted with caution given the limited quantity and quality of the evidence.

Native liver histology after successful portoenterostomy in biliary atresia

BACKGROUND

Biliary atresia is the most common indication for childhood liver transplantation. The effects of successful portoenterostomy (PE) on native liver histology remain unclear.

AIMS

We assessed changes in native liver histology after a successful PE in relation to liver function and clinical outcomes.

METHODS

In total, 70 native liver biopsies of 44 biliary atresia patients were obtained at PE (n=30), 4.2 years after successful PE (n=23) and 1.1 years after failed PE (n=17), and reviewed for cholestasis, fibrosis, inflammation, and cytokeratin 7 (CK7) immunopositivity (chronic cholestasis). Ten transplant donor livers served as controls.

RESULTS

After a successful PE [serum bilirubin 11 (2 to 35) μmol/L at biopsy], histologic native liver cholestasis completely resolved in 83% of the patients and portal inflammation significantly decreased. Nevertheless, enhanced fibrosis [Metavir stage 2 (1-4) vs. 4 (1-4)], bile duct proliferation [grade 2 (1-2) vs. 1 (0-2)], and periportal CK7 immunostaining [grade 1 (0-2) vs. 1 (0-4)] persisted in 100%, 87%, and 61% of subjects, respectively. Metavir fibrosis stage corresponded cirrhosis (stage 4) in 52% of the patients, associated with the presence of portal hypertension, and correlated with serum-conjugated bilirubin (r=0.601, P=0.002), bile duct proliferation (r=0.657, P=0.001), and CK7 positivity (r=0.657, P=0.001). Aspartate transferase to platelet ratio index predicted native liver fibrosis and development of esophageal varices. The degree of fibrosis and portal inflammation at PE were unrelated to native liver survival.

CONCLUSIONS

Despite resolution of cholestasis and decreasing inflammation, bile duct proliferation, periportal CK7 immunostaining, and fibrosis persist after successful PE. Fibrosis is associated with biochemical cholestasis, bile duct proliferation, CK7 immunopositivity (chronic cholestasis), and development of portal hypertension.

Characterization of animal models for primary sclerosing cholangitis (PSC)

Primary sclerosing cholangitis (PSC) is a chronic cholangiopathy characterized by biliary fibrosis, development of cholestasis and end stage liver disease, high risk of malignancy, and frequent need for liver transplantation. The poor understanding of its pathogenesis is also reflected in the lack of effective medical treatment. Well-characterized animal models are utterly needed to develop novel pathogenetic concepts and study new treatment strategies. Currently there is no consensus on how to evaluate and characterize potential PSC models, which makes direct comparison of experimental results and effective exchange of study material between research groups difficult. The International Primary Sclerosing Cholangitis Study Group (IPSCSG) has therefore summarized these key issues in a position paper proposing standard requirements for the study of animal models of PSC.

CD8 T cells primed in the gut-associated lymphoid tissue induce immune-mediated cholangitis in mice

The pathogenesis of primary sclerosing cholangitis (PSC) remains poorly understood. Since PSC predominantly occurs in patients with inflammatory bowel disease, autoimmunity triggered by activated T cells migrating from the gut to the liver is a possible mechanism. We hypothesized that T cells primed in the gut-associated lymphoid tissue (GALT) by a specific antigen migrate to the liver and cause cholangitis when they recognize the same antigen on cholangiocytes. We induced ovalbumin-dependent colitis in mice that express ovalbumin in biliary epithelia (ASBT-OVA mice) and crossed ASBT-OVA mice with mice that express ovalbumin in enterocytes (iFABP-OVA mice). We analyzed T-cell activation in the GALT and crossreactivity to the same antigen in the liver as well as the effects of colitis per se on antigen-presentation and T-cell activation in the liver. Intrarectal application of ovalbumin followed by transfer of CD8 OT-I T cells led to antigen-dependent colitis. CD8 T cells primed in the GALT acquired effector function and the capability to migrate to the liver, where they caused cholangitis in a strictly antigen-dependent manner. Likewise, cholangitis developed in mice expressing ovalbumin simultaneously in biliary epithelia and enterocytes after transfer of OT-I T cells. Dextran sodium sulfate colitis led to increased levels of inflammatory cytokines in the portal venous blood, induced activation of resident liver dendritic cells, and promoted the induction of T-cell-dependent cholangitis.

CONCLUSION

Our data strengthen the notion that immune-mediated cholangitis is caused by T cells primed in the GALT and provide the first link between colitis and cholangitis in an antigen-dependent mouse model.

Animal models of chronic liver diseases

Chronic liver diseases are frequent and potentially life threatening for humans. The underlying etiologies are diverse, ranging from viral infections, autoimmune disorders, and intoxications (including alcohol abuse) to imbalanced diets. Although at early stages of disease the liver regenerates in the absence of the insult, advanced stages cannot be healed and may require organ transplantation. A better understanding of underlying mechanisms is mandatory for the design of new drugs to be used in clinic. Therefore, rodent models are being developed to mimic human liver disease. However, no model to date can completely recapitulate the "corresponding" human disorder. Limiting factors are the time frame required in humans to establish a certain liver disease and the fact that rodents possess a distinct immune system compared with humans and have different metabolic rates affecting liver homeostasis. These features account for the difficulties in developing adequate rodent models for studying disease progression and for testing new pharmaceuticals to be translated into the clinic. Nevertheless, traditional and new promising animal models that mimic certain attributes of chronic liver diseases are established and being used to deepen our understanding in the underlying mechanisms of distinct liver diseases. This review aims at providing a comprehensive overview of recent advances in animal models recapitulating different features and etiologies of human liver diseases.

Coagulation and coagulation signalling in fibrosis

Following tissue injury, a complex and coordinated wound healing response comprising coagulation, inflammation, fibroproliferation and tissue remodelling has evolved to nullify the impact of the original insult and reinstate the normal physiological function of the affected organ. Tissue fibrosis is thought to result from a dysregulated wound healing response as a result of continual local injury or impaired control mechanisms. Although the initial insult is highly variable for different organs, in most cases, uncontrolled or sustained activation of mesenchymal cells into highly synthetic myofibroblasts leads to the excessive deposition of extracellular matrix proteins and eventually loss of tissue function. Coagulation was originally thought to be an acute and transient response to tissue injury, responsible primarily for promoting haemostasis by initiating the formation of fibrin plugs to enmesh activated platelets within the walls of damaged blood vessels. However, the last 20years has seen a major re-evaluation of the role of the coagulation cascade following tissue injury and there is now mounting evidence that coagulation plays a critical role in orchestrating subsequent inflammatory and fibroproliferative responses during normal wound healing, as well as in a range of pathological contexts across all major organ systems. This review summarises our current understanding of the role of coagulation and coagulation initiated signalling in the response to tissue injury, as well as the contribution of uncontrolled coagulation to fibrosis of the lung, liver, kidney and heart. This article is part of a Special Issue entitled: Fibrosis: Translation of basic research to human disease.