Dysregulated Bile Transporters and Impaired Tight Junctions During Chronic Liver Injury in Mice

Loss of hepatocyte Usp53 protects mice from a form of xenobiotic-induced liver injury

BACKGROUND

Ubiquitin-specific protease 53 (USP53) deficiency is associated with familial intrahepatic cholestasis in which serum gamma-glutamyl transferase (GGT) activity is relatively low. However, how USP53 deficiency contributes to cholestasis is obscure. No animal model has been reported.

METHODS

Usp53 liver-specific knockout (Usp53 cKO) mice generated by crossing Usp53fl/fl mice with albumin-cre (Alb-cre) recombinase transgenic mice were challenged with dietary cholic acid (CA) or 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC). General well-being, hepatobiliary-injury biomarker values, histopathologic and ultrastructural appearances, and expression of key genes were compared with those in wild-type (WT) littermates. Interactions of USP53 and TJP2 were investigated by immunofluorescence and co-immunoprecipitation.

RESULTS

Usp53 cKO mice exhibited no obvious differences from WT mice when fed with either normal-chow or CA-added diet. However, after 4 weeks of DDC feeding, Usp53 cKO mice lost less weight, were less icteric, had more nearly normal biomarker values, and accumulated less intrahepatic pigment than WT mice. On normal chow, mRNA expression of critical hepatic transporters Abcb11, Ntcp, and Abcc2 was lower in Usp53 cKO liver than in WT liver; after DDC feeding, mRNA expression of Tjp2 was higher, while detoxification enzymes Cyp3a11, Cyp2b10, and Sult2a1 was lower in Usp53 cKO liver than in WT liver, and hepatocellular tight junctions were significantly longer. USP53 interacts with TJP2.

CONCLUSIONS

Usp53 deficiency can protect mice from DDC-induced liver injury. Liver Usp53 cKO causes upregulation of hepatobiliary Tjp2, with biochemical and histologic features that largely mimic those of liver Tjp2 cKO, implying that USP53 deficiency may share similar mechanism to TJP2 deficiency.

ZnR/GPR39 regulates hepatic insulin signaling, tunes liver bioenergetics and ROS production, and mitigates liver fibrosis and injury

Adequate supply of zinc is essential for hepatic function and its deficiency is associated with acute liver injury (ALI) and chronic nonalcoholic fatty liver disease (NAFLD). However, how zinc controls hepatic function is unknown. We found that the zinc sensitive ZnR/GPR39, a mediator of zinc signaling, enhances hepatic phosphorylation of ERK1/2, which is reduced in ZnR/GPR39 deficient livers. Surprisingly, livers from ZnR/GPR39 knockout (KO) mice exhibited elevated insulin receptor expression and downstream AKT activation. Moreover, ZnR/GPR39 KO mice had higher blood fasting glucose level, pronounced hepatic lipid accumulation, increased hepatocyte oxygen consumption rate (OCR) and reactive oxygen species (ROS) levels. These data suggest that ZnR/GPR39 modulates insulin receptor signaling, a major pathway in hepatic metabolism. Associated with the impaired signaling, ZnR/GPR39 KO livers exhibited increased tissue fibrosis, manifested by marked elevation of collagen expression, compared to wildtype (WT). Additionally, we found alteration of hepatocyte junctional proteins that was accompanied by increased macrophage infiltration and higher liver inflammation in ZnR/GPR39 KO mice. To determine the role of ZnR/GPR39 in ALI, we applied a mild LPS challenge that induced profound decrease in hepatic OCR, also leading to higher ROS generation in ZnR/GPR39 KO hepatocytes, but not in WT. We further found increased serum IL-2 and AST/ALT ratio only in ZnR/GPR39 KO mice. Our findings reveal a role of ZnR/GPR39 in controlling hepatic insulin receptor signaling and mitigating liver fibrosis and inflammation, thus underscoring the important role of ZnR/GPR39 in liver signaling and function.

Overcoming Biopotency Barriers: Advanced Oral Delivery Strategies for Enhancing the Efficacy of Bioactive Food Ingredients

Bioactive food ingredients contribute to the promotion and maintenance of human health and wellbeing. However, these functional ingredients often exhibit low biopotency after food processing or gastrointestinal transit. Well-designed oral delivery systems can increase the ability of bioactive food ingredients to resist harsh environments inside and outside the human body, as well as allow for controlled or triggered release of bioactives to specific sites in the gastrointestinal tract or other tissues and organs. This review presents the characteristics of common bioactive food ingredients and then highlights the barriers to their biopotency. It also discusses various oral delivery strategies and carrier types that can be used to overcome these biopotency barriers, with a focus on recent advances in the field. Additionally, the advantages and disadvantages of different delivery strategies are highlighted. Finally, the current challenges facing the development of food-grade oral delivery systems are addressed, and areas where future research can lead to new advances and industrial applications of these systems are proposed.

Tight Junction Proteins as Therapeutic Targets to Treat Liver Fibrosis and Hepatocellular Carcinoma

In the last decade tight junction proteins exposed at the surface of liver or cancer cells have been uncovered as mediators of liver disease biology: Claudin-1 and Occludin are host factors for hepatitis C virus entry and Claudin-1 has been identified as a driver for liver fibrosis and hepatocellular carcinoma (HCC). Moreover, Claudins have emerged as therapeutic targets for liver disease and HCC. CLDN1 expression is upregulated in liver fibrosis and HCC. Monoclonal antibodies (mAbs) targeting Claudin-1 have completed preclinical proof-of-concept studies for treatment of liver fibrosis and HCC and are currently in clinical development for advanced liver fibrosis. Claudin-6 overexpression is associated with an HCC aggressive phenotype and treatment resistance. Claudin-6 mAbs or chimeric antigen receptor-T cells therapies are currently being clinically investigated for Claudin-6 overexpressing tumors. In conclusion, targeting Claudin proteins offers a novel clinical opportunity for the treatment of patients with advanced liver fibrosis and HCC.

Impaired hemoglobin clearance by sinusoidal endothelium promotes vaso-occlusion and liver injury in sickle cell disease

Sickle cell disease (SCD) is a monogenic disorder that affects 100,000 African-Americans and millions of people worldwide. Intra-erythrocytic polymerization of sickle hemoglobin (HbS) promotes erythrocyte sickling, impaired rheology, ischemia and hemolysis, leading to the development of progressive liver injury in SCD. Liver-resident macrophages and monocytes are known to enable the clearance of HbS; however, the role of liver sinusoidal endothelial cells (LSEC) in HbS clearance and liver injury in SCD remains unknown. Using real-time intravital (in vivo) imaging in mice liver as well as flow cytometric analysis and confocal imaging of primary human LSEC, we show for the first time that liver injury in SCD is associated with accumulation of HbS and iron in the LSEC, leading to senescence of these cells. Hemoglobin uptake by LSEC was mediated by micropinocytosis. Hepatic monocytes were observed to attenuate LSEC senescence by accelerating HbS clearance in the liver of SCD mice; however, this protection was impaired in P-selectin-deficient SCD mice secondary to reduced monocyte recruitment in the liver. These findings are the first to suggest that LSEC contribute to HbS clearance and HbS-induced LSEC senescence promotes progressive liver injury in SCD mice. Our results provide a novel insight into the pathogenesis of hemolysis-induced chronic liver injury in SCD caused by LSEC senescence. Identifying the regulators of LSEC-mediated HbS clearance may lead to new therapies to prevent the progression of liver injury in SCD.

Pediatric Cholestatic Diseases: Common and Unique Pathogenic Mechanisms

Cholestasis is the predominate feature of many pediatric hepatobiliary diseases. The physiologic flow of bile requires multiple complex processes working in concert. Bile acid (BA) synthesis and excretion, the formation and flow of bile, and the enterohepatic reuptake of BAs all function to maintain the circulation of BAs, a key molecule in lipid digestion, metabolic and cellular signaling, and, as discussed in the review, a crucial mediator in the pathogenesis of cholestasis. Disruption of one or several of these steps can result in the accumulation of toxic BAs in bile ducts and hepatocytes leading to inflammation, fibrosis, and, over time, biliary and hepatic cirrhosis. Biliary atresia, progressive familial intrahepatic cholestasis, primary sclerosing cholangitis, and Alagille syndrome are four of the most common pediatric cholestatic conditions. Through understanding the commonalities and differences in these diseases, the important cellular mechanistic underpinnings of cholestasis can be greater appreciated.

Time-of-day-dependent variation of the human liver transcriptome and metabolome is disrupted in MASLD

Background & Aims

Liver homeostasis is ensured in part by time-of-day-dependent processes, many of them being paced by the molecular circadian clock. Liver functions are compromised in metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH), and clock disruption increases susceptibility to MASLD progression in rodent models. We therefore investigated whether the time-of-day-dependent transcriptome and metabolome are significantly altered in human steatotic and MASH livers.

Methods

Liver biopsies, collected within an 8 h-window from a carefully phenotyped cohort of 290 patients and histologically diagnosed to be either normal, steatotic or MASH hepatic tissues, were analyzed by RNA sequencing and unbiased metabolomic approaches. Time-of-day-dependent gene expression patterns and metabolomes were identified and compared between histologically normal, steatotic and MASH livers.

Results

Herein, we provide a first-of-its-kind report of a daytime-resolved human liver transcriptome-metabolome and associated alterations in MASLD. Transcriptomic analysis showed a robustness of core molecular clock components in steatotic and MASH livers. It also revealed stage-specific, time-of-day-dependent alterations of hundreds of transcripts involved in cell-to-cell communication, intracellular signaling and metabolism. Similarly, rhythmic amino acid and lipid metabolomes were affected in pathological livers. Both TNFα and PPARγ signaling were predicted as important contributors to altered rhythmicity.

Conclusion

MASLD progression to MASH perturbs time-of-day-dependent processes in human livers, while the differential expression of core molecular clock components is maintained.

Impact and implications

This work characterizes the rhythmic patterns of the transcriptome and metabolome in the human liver. Using a cohort of well-phenotyped patients (n = 290) for whom the time-of-day at biopsy collection was known, we show that time-of-day variations observed in histologically normal livers are gradually perturbed in liver steatosis and metabolic dysfunction-associated steatohepatitis. Importantly, these observations, albeit obtained across a restricted time window, provide further support for preclinical studies demonstrating alterations of rhythmic patterns in diseased livers. On a practical note, this study indicates the importance of considering time-of-day as a critical biological variable which may significantly affect data interpretation in animal and human studies of liver diseases.

Wnt-β-catenin in hepatobiliary homeostasis, injury, and repair

Wnt-β-catenin signaling has emerged as an important regulatory pathway in the liver, playing key roles in zonation and mediating contextual hepatobiliary repair after injuries. In this review, we will address the major advances in understanding the role of Wnt signaling in hepatic zonation, regeneration, and cholestasis-induced injury. We will also touch on some important unanswered questions and discuss the relevance of modulating the pathway to provide therapies for complex liver pathologies that remain a continued unmet clinical need.

Long-Term L-Glutamine Treatment Reduces Hemolysis without Ameliorating Hepatic Vaso-Occlusion and Liver Fibrosis in a Mouse Model of Sickle Cell Disease

Sickle cell disease (SCD) is an autosomal recessive monogenic disorder caused by a homozygous mutation in the β-globin gene, which leads to erythrocyte sickling, hemolysis, vaso-occlusion, and sterile inflammation. The administration of oral L-glutamine has been shown to reduce the frequency of pain in SCD patients; however, the long-term effect of L-glutamine in SCD remains to be determined. To understand the long-term effect of L-glutamine administration in the liver we used quantitative liver intravital microscopy and biochemical analysis in humanized SCD mice. We here show that chronic L-glutamine administration reduces hepatic hemoglobin-heme-iron levels but fails to ameliorate ischemic liver injury. Remarkably, we found that this failure in the resolution of hepatobiliary injury and persistent liver fibrosis is associated with the reduced expression of hepatic Kupffer cells post-L-glutamine treatment. These findings establish the importance of investigating the long-term effects of L-glutamine therapy on liver pathophysiology in SCD patients.

Dimethyl Sulfoxide Inhibits Bile Acid Synthesis in Healthy Mice but Does Not Protect Mice from Bile-Acid-Induced Liver Damage

Bile acids serve a vital function in lipid digestion and absorption; however, their accumulation can precipitate liver damage. In our study, we probed the effects of dimethyl sulfoxide (DMSO) on bile acid synthesis and the ensuing liver damage in mice induced by bile acids. Our findings indicate that DMSO efficaciously curbs bile acid synthesis by inhibiting key enzymes involved in the biosynthetic pathway, both in cultured primary hepatocytes and in vivo. Contrarily, we observed that DMSO treatment did not confer protection against bile-acid-induced liver damage in two distinct mouse models: one induced by a 0.1% DDC diet, leading to bile duct obstruction, and another induced by a CDA-HFD, resulting in non-alcoholic steatohepatitis (NASH). Histopathological and biochemical analyses unveiled a comparable extent of liver injury and fibrosis levels in DMSO-treated mice, characterized by similar levels of increase in Col1a1 and Acta2 expression and equivalent total liver collagen levels. These results suggest that, while DMSO can promptly inhibit bile acid synthesis in healthy mice, compensatory mechanisms might rapidly override this effect, negating any protective impact against bile-acid-induced liver damage in mice. Through these findings, our study underscores the need to reconsider treating DMSO as a mere inert solvent and prompts further exploration to identify more effective therapeutic strategies for the prevention and treatment of bile-acid-associated liver diseases.

Open hepatic artery flow with portal vein clamping protects against bile duct injury compared to pringles maneuver

BACKGROUND

Conventional hepatic artery and portal vein clamping strategies can prevent blood loss and ischemia-reperfusion liver injury, and such preventative measures are the key to successful liver surgery. However, ischemic-induced damage to cholangiocytes is rarely considered. Here, we aimed to investigate the effect of different hepatic inflow interruption methods on bile duct injury.

METHODS

Forty rats were randomly grouped as sham, Pringle maneuver (PM) and hepatic arterial blood flow open (HAFO) groups. We evaluated liver histology and function in liver sections, and biliary histology, cholangiocyte apoptosis and proliferation, cytokine production, and bile composition. RNA sequencing is performed to explore possible molecular mechanisms. The Blood-biliary barrier permeability and tight junctions were analyzed by HRP injection, immunofluorescence staining and analysis of ZO-1 expression by immunoblotting.

RESULTS

HAFO significantly attenuated ischemia-induced liver injury and decreased ALT, ALP, TBIL, and DBIL levels in serum. The histopathological observations showed that bile duct injury in the PM group was more serious than that in the HAFO group. The numbers of apoptotic biliary epithelial cells in HAFO-treated rat bile ducta were lower than those in the PM group. RNA-seq showed that tight junctions may be related to the mechanism underlying the protective effect of HAFO, as shown by the reduced HRP levels and increased ZO-1 and claudin-1/3 expression in the HAFO group compared to the PM group.

CONCLUSION

Compared with PM, HAFO alleviated the ischemic injury to the biliary system, which was characterized by decreased biliary epithelial cell apoptosis, reduced inflammatory responses and decreased blood-biliary-barrier permeability.

Placental transfer of bisphenol diglycidyl ethers (BDGEs) and its association with maternal health in a population in South of China

Despite high production and usage, little is known about exposure to bisphenol diglycidyl ethers (BDGEs) and their derivatives in pregnant women and fetuses. In this study, we determined nine BDGEs in 106 paired maternal and cord serum samples collected from e-waste dismantling sites in South of China. Bisphenol A bis (2,3-dihydroxypropyl) glycidyl ether (BADGE·2H2O), bisphenol A (3-chloro-2-hydroxypropyl) (2,3-dihydroxypropyl) glycidyl ether (BADGE·HCl·H2O), and bisphenol F diglycidyl ether (BFDGE) were the major BDGEs, with median concentrations of 0.57, 4.07, and 1.60 ng/mL, respectively, in maternal serum, and of 3.58, 5.61, and 0.61 ng/mL, respectively, in cord serum. The transplacental transfer efficiencies (TTEs) were estimated for BDGEs found in samples, and median values were in the range of 0.98 (BFDGE) to 5.91 (BADGE·2H2O). Our results suggested that passive diffusion plays a role in the placental transfer of BADGE·HCl·H2O and BFDGE, whereas several mechanisms contribute to the high accumulation of BADGE·2H2O in cord serum. Multiple linear regression analysis indicated significant associations between maternal serum concentrations of BDGEs and blood clinical biomarkers, especially those related to liver injuries, such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and adenosine deaminase (ADA) (P < 0.05). To our knowledge, this is the first study to report the occurrence of BDGEs in paired maternal-fetal serum samples and provide new insights into prenatal and fetal exposures. The newly discovered TTEs in maternal-fetal pairs contribute to a fuller inventory of the transmission activity of pollutants in the human body, ultimately adding to a more significant comprehensive risk evaluation.

Urine metabolomics and microbiome analyses reveal the mechanism of anti-tuberculosis drug-induced liver injury, as assessed for causality using the updated RUCAM: A prospective study

Background

Anti-tuberculosis drug-induced liver injury (ATB-DILI) is one of the most common adverse reactions that brings great difficulties to the treatment of tuberculosis. Thus, early identification of individuals at risk for ATB-DILI is urgent. We conducted a prospective cohort study to analyze the urinary metabolic and microbial profiles of patients with ATB-DILI before drug administration. And machine learning method was used to perform prediction model for ATB-DILI based on metabolomics, microbiome and clinical data.

Methods

A total of 74 new TB patients treated with standard first-line anti-TB treatment regimens were enrolled from West China Hospital of Sichuan University. Only patients with an updated RUCAM score of 6 or more were accepted in this study. Nontargeted metabolomics and microbiome analyses were performed on urine samples prior to anti-tuberculosis drug ingestion to screen the differential metabolites and microbes between the ATB-DILI group and the non-ATB-DILI group. Integrating electronic medical records, metabolomics, and microbiome data, four machine learning methods was used, including random forest algorithm, artificial neural network, support vector machine with the linear kernel and radial basis function kernel.

Results

Of all included patients, 69 patients completed follow-up, with 16 (23.19%) patients developing ATB-DILI after antituberculosis treatment. Finally, 14 ATB-DILI patients and 30 age- and sex-matched non-ATB-DILI patients were subjected to urinary metabolomic and microbiome analysis. A total of 28 major differential metabolites were screened out, involving bile secretion, nicotinate and nicotinamide metabolism, tryptophan metabolism, ABC transporters, etc. Negativicoccus and Actinotignum were upregulated in the ATB-DILI group. Multivariate analysis also showed significant metabolic and microbial differences between the non-ATB-DILI and severe ATB-DILI groups. Finally, the four models showed high accuracy in predicting ATB-DILI, with the area under the curve of more than 0.85 for the training set and 1 for the validation set.

Conclusion

This study characterized the metabolic and microbial profile of ATB-DILI risk individuals before drug ingestion for the first time. Metabolomic and microbiome characteristics in patient urine before anti-tuberculosis drug ingestion may predict the risk of liver injury after ingesting anti-tuberculosis drugs. Machine learning algorithms provides a new way to predict the occurrence of ATB-DILI among tuberculosis patients.

Plasma metabolomic and lipidomic alterations associated with anti-tuberculosis drug-induced liver injury

Background: Anti-tuberculosis drug-induced liver injury (ATB-DILI) is an adverse reaction with a high incidence and the greatest impact on tuberculosis treatment. However, there is a lack of effective biomarkers for the early prediction of ATB-DILI. Herein, this study uses UPLC‒MS/MS to reveal the plasma metabolic profile and lipid profile of ATB-DILI patients before drug administration and screen new biomarkers for predicting ATB-DILI. Methods: A total of 60 TB patients were enrolled, and plasma was collected before antituberculosis drug administration. The untargeted metabolomics and lipidomics analyses were performed using UPLC‒MS/MS, and the high-resolution mass spectrometer Q Exactive was used for data acquisition in both positive and negative ion modes. The random forest package of R software was used for data screening and model building. Results: A total of 60 TB patients, including 30 ATB-DILI patients and 30 non-ATB-DILI subjects, were enrolled. There were no significant differences between the ATB-DILI and control groups in age, sex, smoking, drinking or body mass index (p > 0.05). Twenty-two differential metabolites were selected. According to KEGG pathway analysis, 9 significantly enriched metabolic pathways were found, and both drug metabolism-other enzymes and niacin and nicotinamide metabolic pathways were found in both positive and negative ion models. A total of 7 differential lipid molecules were identified between the two groups. Ferroptosis and biosynthesis of unsaturated fatty acids were involved in the occurrence of ATB-DILI. Random forest analysis showed that the model built with the top 30 important variables had an area under the ROC curve of 0.79 (0.65-0.93) for the training set and 0.79 (0.55-1.00) for the validation set. Conclusion: This study demonstrated that potential markers for the early prediction of ATB-DILI can be found through plasma metabolomics and lipidomics. The random forest model showed good clinical predictive value for ATB-DILI.

Loss of heat shock factor 1 promotes hepatic stellate cell activation and drives liver fibrosis

Liver fibrosis is an aberrant wound healing response that results from chronic injury and is mediated by hepatocellular death and activation of hepatic stellate cells (HSCs). While induction of oxidative stress is well established in fibrotic livers, there is limited information on stress-mediated mechanisms of HSC activation. Cellular stress triggers an adaptive defense mechanism via master protein homeostasis regulator, heat shock factor 1 (HSF1), which induces heat shock proteins to respond to proteotoxic stress. Although the importance of HSF1 in restoring cellular homeostasis is well-established, its potential role in liver fibrosis is unknown. Here, we show that HSF1 messenger RNA is induced in human cirrhotic and murine fibrotic livers. Hepatocytes exhibit nuclear HSF1, whereas stellate cells expressing alpha smooth muscle actin do not express nuclear HSF1 in human cirrhosis. Interestingly, despite nuclear HSF1, murine fibrotic livers did not show induction of HSF1 DNA binding activity compared with controls. HSF1-deficient mice exhibit augmented HSC activation and fibrosis despite limited pro-inflammatory cytokine response and display delayed fibrosis resolution. Stellate cell and hepatocyte-specific HSF1 knockout mice exhibit higher induction of profibrogenic response, suggesting an important role for HSF1 in HSC activation and fibrosis. Stable expression of dominant negative HSF1 promotes fibrogenic activation of HSCs. Overactivation of HSF1 decreased phosphorylation of JNK and prevented HSC activation, supporting a protective role for HSF1. Our findings identify an unconventional role for HSF1 in liver fibrosis. Conclusion: Our results show that deficiency of HSF1 is associated with exacerbated HSC activation promoting liver fibrosis, whereas activation of HSF1 prevents profibrogenic HSC activation.

Liver-to-lung microembolic NETs promote gasdermin D-dependent inflammatory lung injury in sickle cell disease

Acute lung injury, referred to as the acute chest syndrome, is a major cause of morbidity and mortality in patients with sickle cell disease (SCD), which often occurs in the setting of a vaso-occlusive painful crisis. P-selectin antibody therapy reduces hospitalization of patients with SCD by ∼50%, suggesting that an unknown P-selectin-independent mechanism promotes remaining vaso-occlusive events. In patients with SCD, intraerythrocytic polymerization of mutant hemoglobin promotes ischemia-reperfusion injury and hemolysis, which leads to the development of sterile inflammation. Using intravital microscopy in transgenic, humanized mice with SCD and in vitro studies with blood from patients with SCD, we reveal for the first time that the sterile inflammatory milieu in SCD promotes caspase-4/11-dependent activation of neutrophil-gasdermin D (GSDMD), which triggers P-selectin-independent shedding of neutrophil extracellular traps (NETs) in the liver. Remarkably, these NETs travel intravascularly from liver to lung, where they promote neutrophil-platelet aggregation and the development of acute lung injury. This study introduces a novel paradigm that liver-to-lung embolic translocation of NETs promotes pulmonary vascular vaso-occlusion and identifies a new GSDMD-mediated, P-selectin-independent mechanism of lung injury in SCD.

Modulation of Disordered Bile Acid Homeostasis and Hepatic Tight Junctions Using Salidroside against Hepatocyte Apoptosis in Furan-Induced Mice

Furan, a processing-induced food contaminant, has attracted great attention due to its hepatotoxicity. To further investigate the underlying mechanism of salidroside (SAL) alleviating furan-induced liver damage, we divided Balb/c mice into the control group, the furan (8 mg/kg/day) group, and three groups of three different doses of SAL (10/20/40 mg/kg/day) in the current research. The shifted serum profile was observed through untargeted metabonomics, to which the bile acid metabolism was related, and the alleviating effect of SAL against furan-induced apoptosis was caused by the metabolism. Target bile acid quantification for the liver and serum showed that SAL positively regulated the homeostasis of bile acids disturbed by furan. Meanwhile, SAL significantly upregulated the synthesis genes of bile acids (Cyp7a1, Cyp7b1, Cyp8b1, and Cyp27a1) and the uptake transport genes (Ntcp and Oatps) and downregulated the efflux transport genes (Bsep, Ost-α, Ost-β, Mrp2, and Mrp4). Transmission electron microscopy of the bile canaliculi and tight junctions and the levels of tight junction marker proteins (ZO-1, occludin, and claudin-1) confirmed that the disruption of the hepatic tight junction was inhibited by SAL. The connection between the apoptosis- and tight junction-related proteins was observed through the construction of a protein-protein interaction network. SAL suppressed the furan-induced hepatocyte apoptosis evidenced by the detection of TUNEL and Bax, Bcl-2, and caspase-3 levels. Taken together, SAL alleviated furan-induced hepatocyte apoptosis via altering the disordered homeostasis of bile acids and hepatic tight junctions.

The Role of Gut Microbiota in Some Liver Diseases: From an Immunological Perspective

Gut microbiota is a microecosystem composed of various microorganisms. It plays an important role in human metabolism, and its metabolites affect different tissues and organs. Intestinal flora maintains the intestinal mucosal barrier and interacts with the immune system. The liver is closely linked to the intestine by the gut-liver axis. As the first organ that comes into contact with blood from the intestine, the liver will be deeply influenced by the gut microbiota and its metabolites, and the intestinal leakage and the imbalance of the flora are the trigger of the pathological reaction of the liver. In this paper, we discuss the role of gut microbiota and its metabolites in the pathogenesis and development of autoimmune liver diseases((including autoimmune hepatitis, primary biliary cirrhosis, primary sclerosing cholangitis), metabolic liver disease such as non-alcoholic fatty liver disease, cirrhosisits and its complications, and liver cancer from the perspective of immune mechanism. And the recent progress in the treatment of these diseases was reviewed from the perspective of gut microbiota.

Defenestrated endothelium delays liver-directed gene transfer in hemophilia A mice

Hemophilia A is an inherited bleeding disorder caused by defective or deficient coagulation factor VIII (FVIII) activity. Until recently, the only treatment for prevention of bleeding involved IV administration of FVIII. Gene therapy with adeno-associated vectors (AAVs) has shown some efficacy in patients with hemophilia A. However, limitations persist due to AAV-induced cellular stress, immunogenicity, and reduced durability of gene expression. Herein, we examined the efficacy of liver-directed gene transfer in FVIII knock-out mice by AAV8-GFP. Surprisingly, compared with control mice, FVIII knockout (F8TKO) mice showed significant delay in AAV8-GFP transfer in the liver. We found that the delay in liver-directed gene transfer in F8TKO mice was associated with absence of liver sinusoidal endothelial cell (LSEC) fenestration, which led to aberrant expression of several sinusoidal endothelial proteins, causing increased capillarization and decreased permeability of LSECs. This is the first study to link impaired liver-directed gene transfer to liver-endothelium maladaptive structural changes associated with FVIII deficiency in mice.

Intravital imaging reveals inflammation as a dominant pathophysiology of age-related hepatovascular changes

Aging is the most significant risk factor for the majority of chronic diseases, including liver disease. The cellular, molecular, and pathophysiological mechanisms that promote age-induced hepatovascular changes are unknown due to our inability to visualize changes in liver pathophysiology in live mice over time. We performed quantitative liver intravital microscopy (qLIM) in live C57BL/6J mice to investigate the impact of aging on the hepatovascular system over a 24-mo period. qLIM revealed that age-related hepatic alterations include reduced liver sinusoidal blood flow, increased sinusoidal vessel diameter, and loss of small hepatic vessels. The ductular cell structure deteriorates with age, along with altered expression of hepatic junctional proteins. Furthermore, qLIM imaging revealed increased inflammation in the aged liver, which was linked to increased expression of proinflammatory macrophages, hepatic neutrophils, liver sinusoidal endothelial cells, senescent cells, and procoagulants. Finally, we detected elevated NF-κB pathway activity in aged livers. Overall, these findings emphasize the importance of inflammation in age-related hepatic vasculo-epithelial alterations and highlight the utility of qLIM in studying age-related effects in organ pathophysiology.

Human menstrual blood-derived stem cell transplantation suppresses liver injury in DDC-induced chronic cholestasis

Background

Cholestatic liver injury can lead to serious symptoms and prognoses in the clinic. Currently, an effective medical treatment is not available for cholestatic liver injury. Human menstrual blood-derived stem cells (MenSCs) are considered as an emerging treatment in various diseases. This study aimed to explore the treatment effect of MenSCs in cholestatic liver injury.

Methods

The treatment effect of MenSCs on chronic cholestatic liver injury was verified in 3,5-diethoxycarbonyl-1,4-dihydroxychollidine (DDC)-induced C57/BL6 mice. Pathological, fibrosis area in the liver tissue and serum liver enzymes were tested. Proteomics and western blot were used to explore the related targets and molecular mechanisms. Adeno-associated virus (AAV) 9-infected mice were applied for verification.

Results

MenSCs markedly improved the survival rate of the DDC-treated mice (60% vs. 100%), and decreased the mouse serum aspartate aminotransferase (AST) (169.4 vs. 108.0 U/L, p < 0.001), alanine aminotransferase (ALT) (279.0 vs. 228.9 U/L, p < 0.01), alkaline phosphatase (ALP) (45.6 vs. 10.6 U/L, p < 0.0001), direct bilirubin (DBIL) (108.3 vs. 14.0 μmol/L, p < 0.0001) and total bilirubin (TBIL) (179.2 vs. 43.3 μmol/L, p < 0.0001) levels as well as intrahepatic cholestasis, bile duct dilation and fibrotic areas (16.12 vs. 6.57%, p < 0.05). The results further indicated that MenSCs repaired the DDC-induced liver tight junction (TJ) pathway and bile transporter (OATP2, BSEP and NTCP1) injury, thereby inhibiting COL1A1, α-SMA and TGF-β1 activation by upregulating liver β-catenin expression.

Conclusions

MenSC transplantation could be an effective treatment method for cholestatic liver injury in mice. MenSCs may exhibit therapeutic effects by regulating β-catenin expression.

TGF-β/YB-1/Atg7 axis promotes the proliferation of hepatic progenitor cells and liver fibrogenesis

Hepatic fibrosis is characterized by excessive extracellular matrix deposition and ductular reactions, manifested as the expansion of hepatic progenitor cells (HPCs). We previously reported that the Y-box binding protein 1 (YB-1) in HPCs is involved in chronic liver injury. In this study, we constructed YB-1f/f Foxl1-Cre mice and investigated the role of YB-1 in HPC expansion in murine choline-deficient, ethionine-supplemented (CDE), and 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) models. Liver injury and fibrosis were measured using hematoxylin and eosin (HE), Masson, and Sirius Red staining. HPC proliferation was detected using EdU and immunofluorescence (IF). Autophagic flow was measured by mCherry-GFP-LC3B staining and transmission electron microscopy (TEM). YB-1 expression was measured by immunofluorescence and western blotting. CUT & Tag analysis, chromatin immunoprecipitation, and RT-PCR were performed to explore the regulation of autophagy-related protein 7 (Atg7) transcription by YB-1. Our results indicated that liver injury was accompanied by high expression of YB-1, proliferative HPCs, and activated autophagy in the CDE and DDC models. YB-1f/f Cre+/- mice displayed less liver injury and fibrosis than YB-1f/f Cre-/- mice in the CDE and DDC models. YB-1 promoted proliferation and autophagy of HPCs in vitro and in vivo. Transforming growth factor-β (TGF-β) induced YB-1 nuclear translocation and facilitated the proliferation and autophagy of HPCs. YB-1 nuclear translocation promoted the transcription of Atg7, which is essential for TGF-β/YB-1 mediated HPCs expansion in vitro and in vivo. In summary, YB-1 nuclear translocation induced by TGF-β in HPCs promotes the proliferation and autophagy of HPCs and Atg7 participates in YB-1-mediated HPC-expansion and liver fibrosis.

Prevotella copri ameliorates cholestasis and liver fibrosis in primary sclerosing cholangitis by enhancing the FXR signalling pathway

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease characterized by bile duct inflammation, fibrosis, bile acid (BA) metabolism disorders and gut microbiota dysbiosis. At present, the aetiology and pathogenesis of PSC are not clear, and there is no specific or effective treatment available. Therefore, new research perspectives are needed to explore effective methods to treat PSC and improve symptoms. The intestinal microbiota of patients with PSC is known to be significantly different from that of healthy people. By comparing differentially abundant bacterial genera in PSC patients, it was found that the abundance of Prevotella copri (P. copri) was significantly decreased, suggesting that this species may have a protective effect against PSC disease. Therefore, comprehensively exploring the role and possible function of P. copri in the disease process is worthwhile. In this study, a PSC mouse model was established by feeding mice a customized diet supplemented with 0.1% (w/w) 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) for one week, and the abundance of P. copri was confirmed to be decreased in this model. Previous studies in patients and animal models have demonstrated that gut microbiota intervention is an acceptable treatment for some diseases. We found that intervention with P. copri could significantly improve cholestasis and liver fibrosis by enhancing the FXR-related signalling pathway in PSC mice. Together, through the overall effect of P. copri on intestinal microbiota structure and its association with BAs, we speculate that P. copri intervention might be as potential biological treatment of PSC.

Review of studies of severe acute respiratory syndrome related coronavirus-2 pathogenesis in human organoid models

Severe acute respiratory syndrome related coronavirus-2 (SARS-CoV-2) is the cause of Covid-19 which was classified as a global pandemic in March 2020. The increasing global health and economic burden of SARS-CoV-2 has necessitated urgent investigations into the pathogenesis of disease and development of therapeutic and vaccination regimens. Human trials of vaccine and antiviral candidates have been undertaken, but basic pathogenetic studies are still required to inform these trials. Gaps in understanding of cellular infection by, and immunity to, SARS-CoV-2 mean additional models are required to assist in improved design of these therapeutics. Human organoids are three-dimensional models that contain multiple cell types and mimic human organs in ex vivo culture conditions. The SARS-CoV-2 virus has been implicated in causing not only respiratory injury but also injury to other organs such as the brain, liver and kidneys. Consequently, a variety of different organoid models have been employed to investigate the pathogenic mechanisms of disease due to SARS-CoV-2. Data on these models have not been systematically assembled. In this review, we highlight key findings from studies that have utilised different human organoid types to investigate the expression of SARS-CoV-2 receptors, permissiveness, immune response, dysregulation of cellular functions, and potential antiviral therapeutics.

β-Catenin-NF-κB-CFTR interactions in cholangiocytes regulate inflammation and fibrosis during ductular reaction

Expansion of biliary epithelial cells (BECs) during ductular reaction (DR) is observed in liver diseases including cystic fibrosis (CF), and associated with inflammation and fibrosis, albeit without complete understanding of underlying mechanism. Using two different genetic mouse knockouts of β-catenin, one with β-catenin loss is hepatocytes and BECs (KO1), and another with loss in only hepatocytes (KO2), we demonstrate disparate long-term repair after an initial injury by 2-week choline-deficient ethionine-supplemented diet. KO2 show gradual liver repopulation with BEC-derived β-catenin-positive hepatocytes and resolution of injury. KO1 showed persistent loss of β-catenin, NF-κB activation in BECs, progressive DR and fibrosis, reminiscent of CF histology. We identify interactions of β-catenin, NFκB, and CF transmembranous conductance regulator (CFTR) in BECs. Loss of CFTR or β-catenin led to NF-κB activation, DR, and inflammation. Thus, we report a novel β-catenin-NFκB-CFTR interactome in BECs, and its disruption may contribute to hepatic pathology of CF.

The liver has an incredible capacity to repair itself or ‘regenerate’ – that is, it has the ability to replace damaged tissue with new tissue. In order to do this, the organ relies on hepatocytes (the cells that form the liver) and bile duct cells (the cells that form the biliary ducts) dividing and transforming into each other to repair and replace damaged tissue, in case the insult is dire.

During long-lasting or chronic liver injury, bile duct cells undergo a process called ‘ductular reaction’, which causes the cells to multiply and produce proteins that stimulate inflammation, and can lead to liver scarring (fibrosis). Ductular reaction is a hallmark of severe liver disease, and different diseases exhibit ductular reactions with distinct features. For example, in cystic fibrosis, a unique type of ductular reaction occurs at late stages, accompanied by both inflammation and fibrosis. Despite the role that ductular reaction plays in liver disease, it is not well understood how it works at the molecular level.

Hu et al. set out to investigate how a protein called β-catenin – which can cause many types of cells to proliferate – is involved in ductular reaction. They used three types of mice for their experiments: wild-type mice, which were not genetically modified; and two strains of genetically modified mice. One of these mutant mice did not produce β-catenin in biliary duct cells, while the other lacked β-catenin both in biliary duct cells and in hepatocytes.

After a short liver injury – which Hu et al. caused by feeding the mice a specific diet – the wild-type mice were able to regenerate and repair the liver without exhibiting any ductular reaction. The mutant mice that lacked β-catenin in hepatocytes showed a temporary ductular reaction, and ultimately repaired their livers by turning bile duct cells into hepatocytes. On the other hand, the mutant mice lacking β-catenin in both hepatocytes and bile duct cells displayed sustained ductular reactions, inflammation and fibrosis, which looked like that seen in patients with liver disease associated to cystic fibrosis. Further probing showed that β-catenin interacts with a protein called CTFR, which is involved in cystic fibrosis. When bile duct cells lack either of these proteins, another protein called NF-B gets activated, which causes the ductular reaction, leading to inflammation and fibrosis.

The findings of Hu et al. shed light on the role of β-catenin in ductular reaction. Further, the results show a previously unknown interaction between β-catenin, CTFR and NF-B, which could lead to better treatments for cystic fibrosis in the future.

Intravital Imaging of Hepatic Blood Biliary Barrier in Live Mice

Understanding the kinetics and spatiotemporal interactions of living cells within the tissue environment requires real-time imaging. The introduction of two-photon microscopy has substantially boosted the power of live intravital imaging, making it possible to obtain information of individual cells in near-physiologic conditions within intact tissues nondestructively. Intravital imaging of the liver has proved useful in understanding its 3D structure, function, and dynamic cellular interactions. Recently we have shown that integrity of the blood-bile barrier in different physiologic and pathophysiologic conditions can be imaged in real time using intravital microscopy. Here we discuss the real-time intravital imaging method to visualize blood-bile barrier integrity in the murine liver. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Live imaging in the mouse liver Support Protocol: Monitoring vital signs of the mouse during live liver imaging Basic Protocol 2: Visualizing blood and bile transport using intravital microscopy.

Compensatory hepatic adaptation accompanies permanent absence of intrahepatic biliary network due to YAP1 loss in liver progenitors

Yes-associated protein 1 (YAP1) regulates cell plasticity during liver injury, regeneration, and cancer, but its role in liver development is unknown. We detect YAP1 activity in biliary cells and in cells at the hepatobiliary bifurcation in single-cell RNA sequencing analysis of developing livers. Deletion of Yap1 in hepatoblasts does not impair Notch-driven SOX9+ ductal plate formation but does prevent the formation of the abutting second layer of SOX9+ ductal cells, blocking the formation of a patent intrahepatic biliary tree. Intriguingly, these mice survive for 8 months with severe cholestatic injury and without hepatocyte-to-biliary transdifferentiation. Ductular reaction in the perihilar region suggests extrahepatic biliary proliferation, likely seeking the missing intrahepatic biliary network. Long-term survival of these mice occurs through hepatocyte adaptation via reduced metabolic and synthetic function, including altered bile acid metabolism and transport. Overall, we show YAP1 as a key regulator of bile duct development while highlighting a profound adaptive capability of hepatocytes.

P-selectin deficiency promotes liver senescence in sickle cell disease mice

Sickle cell disease (SCD) is caused by a homozygous mutation in the β-globin gene, which leads to erythrocyte sickling, vasoocclusion, and intense hemolysis. P-selectin inhibition has been shown to prevent vasoocclusive events in patients with SCD; however, the chronic effect of P-selectin inhibition in SCD remains to be determined. Here, we used quantitative liver intravital microscopy in our recently generated P-selectin-deficient SCD mice to show that chronic P-selectin deficiency attenuates liver ischemia but fails to prevent hepatobiliary injury. Remarkably, we find that this failure in resolution of hepatobiliary injury in P-selectin-deficient SCD mice is associated with the increase in cellular senescence and reduced epithelial cell proliferation in the liver. These findings highlight the importance of investigating the long-term effects of chronic P-selectin inhibition therapy on liver pathophysiology in patients with SCD.

P-selectin-deficient mice to study pathophysiology of sickle cell disease

P-selectin–deficient SCD mice are protected from lung vaso-occlusion. P-selectin–deficient SCD mice will be useful in assessing the benefits of anti–P-selectin therapy in diverse complications of SCD.

Apigenin protects mice against 3,5-diethoxycarbonyl-1,4-dihydrocollidine-induced cholestasis

Cholestasis can induce liver fibrosis and cirrhosis. Apigenin has anti-oxidant and anti-inflammatory effects. Herein, we determined whether apigenin can protect mice against cholestasis. In vitro, apigenin protected TFK-1 cells (a human bile duct cancer cell line) against H2O2-induced ROS generation and inhibited transforming growth factor-β-activated collagen type 1 alpha 1 and α-smooth muscle actin in LX2 cells (a human hepatic stellate cell line). In vivo, cholestatic mice induced by 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) were treated with apigenin. Apigenin potently blocked DDC-induced gallbladder atrophy and associated liver injury, fibrosis and collagen accumulation. Moreover, apigenin relieved the DDC-caused abnormality of bile acid metabolism and restored the balance between bile secretion and excretion by regulating the farnesoid X receptor signaling pathway. Furthermore, apigenin reduced inflammation or oxidative stress in the liver by blocking the DDC-activated Toll-like receptor 4, nuclear factor κB and tumor necrosis factor α, or DDC-suppressed superoxidase dismutase 1/2, catalase and glutathione peroxidase. Taken together, apigenin improves DDC-induced cholestasis by reducing inflammation and oxidative damage and improving bile acid metabolism, indicating its potential application for cholestasis treatment.

Altered integrity of hepatocyte tight junctions in rats with triptolide-induced cholestasis

Triptolide (TP), an active component of Tripterygium wilfordiiHook. f. (TWHF), has been widely used for centuries as a traditional Chinese medicine. However, the clinical application of TP has been restricted due to multitarget toxicity, such as hepatotoxicity. In this study, 28 days of oral TP administration (100, 200, or 400 μg·kg^-1·d^-1) induced the occurrence of cholestasis in female Wistar rats, as evidenced by increased serum levels of γ-glutamyl transpeptidase (γ-GGT), alkaline phosphatase (ALP) and hepatic total bile acids (TBAs). In addition, the heptocyte polarity associated with the strcture of tight junctions (TJs) was disrupted in both rats and sandwich-cultured primary hepatocytes. Immunoblotting revealed decreased expression of the TJ-associated proteins occludin, claudin-1, and zonula occludens protein (ZO-1), and downregulated mRNA levels of these TJs was also detected by real-time PCR. An immunofluorescence analysis showed abnormal subcellular localization of occludin, claudin-1 and ZO-1, which was also confirmed by transmission electron microscopy. Moreover, the concentration of FITC-dextran, a marker of paracellular penetration, was found to increase rapidly in bile increased rapidly (within 6 minutes) after treatment with TP, which indicated the functional impairment of TJs. Taken together, these results suggest that the administration of TP for 28 consecutive days to rats could induce cholestatic injury in the liver, and the increased paracellular permeability might play an important role in these pathological changes.

The relative expression of hepatocellular and cholestatic liver enzymes in adult patients with liver disease

INTRODUCTION AND OBJECTIVES

Hepatocellular liver injury is characterized by elevations in serum alanine (ALT) and aspartate (AST) aminotransferases while cholestasis is associated with elevated serum alkaline phosphatase (ALP) levels. When both sets of enzymes are elevated, distinguishing between the two patterns of liver disease can be difficult. The aim of this study was to document the predicted ranges of serum ALP values in patients with hepatocellular liver injury and ALT or AST values in patients with cholestasis.

MATERIALS AND METHODS

Liver enzyme levels were documented in adult patients with various types and degrees of hepatocellular (non-alcoholic fatty liver disease, hepatitis B and C, alcohol and autoimmune hepatitis) and cholestatic (primary biliary cholangitis and primary sclerosing cholangitis) disease.

RESULTS

In 5167 hepatocellular disease patients with ALT (or AST) values that were normal, 1-5×, 5-10× or >10× elevated, median (95% CI) serum ALP levels were 0.64 (0.62-0.66), 0.72 (0.71-0.73), 0.80 (0.77-0.82) and 1.15 (1.0-1.22) fold elevated respectively. In 252 cholestatic patients with ALP values that were normal, 1-5× or >5× elevated, serum ALT (or AST) values were 1.13 (0.93-1.63), 2.47 (2.13-2.70) and 4.57 (3.27-5.63) fold elevated respectively. In 56 patients with concurrent diseases, ALP levels were beyond predicted values for their hepatitis in 38 (68%) and ALT (or AST) values beyond predicted values for their cholestatic disorder in 24 (43%).

CONCLUSIONS

These data provide health care providers with predicted ranges of liver enzymes in patients with hepatocellular or cholestatic liver disease and may thereby help to identify patients with concurrent forms of liver disease.

Impaired Bile Secretion Promotes Hepatobiliary Injury in Sickle Cell Disease

BACKGROUND AND AIMS

Hepatic crisis is an emergent complication affecting patients with sickle cell disease (SCD); 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 hepato-pathophysiology applying our recently developed quantitative liver intravital imaging, RNA sequence analysis, and biochemical approaches.

APPROACH AND RESULTS

SCD mice manifested sinusoidal ischemia, progressive hepatomegaly, liver injury, hyperbilirubinemia, and increased ductular reaction under basal conditions. Nuclear factor kappa B (NF-κB) activation in the liver of SCD mice inhibited farnesoid X receptor (FXR) signaling and its downstream targets, leading to loss of canalicular bile transport and altered bile acid pool. Intravital imaging revealed impaired bile secretion into the bile canaliculi, which was secondary to loss of canalicular bile transport and bile acid metabolism, leading to intrahepatic bile accumulation in SCD mouse liver. Blocking NF-κB activation rescued FXR signaling and partially ameliorated liver injury and sinusoidal ischemia in SCD mice.

CONCLUSIONS

These findings identify that NF-κB/FXR-dependent impaired bile secretion promotes intrahepatic bile accumulation, which contributes to hepatobiliary injury of SCD. Improved understanding of these processes could potentially benefit the development of therapies to treat sickle cell hepatic crisis.

Transcriptomic Profiling Identifies Novel Hepatic and Intestinal Genes Following Chronic Plus Binge Ethanol Feeding in Mice

BACKGROUND

Alcohol-associated liver disease accounts for half of cirrhosis-related deaths worldwide. The spectrum of disease varies from simple steatosis to fibrosis, cirrhosis and ultimately hepatocellular carcinoma. Understanding the disease on a molecular level helps us to develop therapeutic targets.

AIM

We performed transcriptomic analysis in liver and ileum from chronic plus binge ethanol-fed mice, and we assessed the role of selected differentially expressed genes and their association with serum bile acids and gut microbiota.

METHODS

Wild-type mice were subjected to a chronic Lieber-DeCarli diet model for 8 weeks followed by one binge of ethanol. RNA-seq analysis was performed on liver and ileum samples. Associations between selected differentially regulated genes and serum bile acid profile or fecal bacterial profiling (16S rDNA sequencing) were investigated.

RESULTS

We provide a comprehensive transcriptomic analysis to identify differentially expressed genes, KEGG pathways, and gene ontology functions in liver and ileum from chronic plus binge ethanol-fed mice. In liver, we identified solute carrier organic anion transporter family, member 1a1 (Slco1a1; encoding for organic anion transporting polypeptides (OATP) 1A1), as the most down-regulated mRNA, and it is negatively correlated with serum cholic acid level. Prokineticin 2 (Prok2) mRNA, a cytokine-like molecule associated with gastrointestinal tract inflammation, was significantly down-regulated in ethanol-fed mice. Prok2 mRNA expression was negatively correlated with abundance of Allobaculum (genus), Coprococcus (genus), Lachnospiraceae (family), Lactococcus (genus), and Cobriobacteriaceae (family), while it positively correlated with Bacteroides (genus).

CONCLUSIONS

RNA-seq analysis revealed unique transcriptomic signatures in the liver and intestine following chronic plus binge ethanol feeding.

Intestinal Microbiome-Macrophage Crosstalk Contributes to Cholestatic Liver Disease by Promoting Intestinal Permeability in Mice

BACKGROUND AND AIMS

Mounting evidence supports an association between cholestatic liver disease and changes in the composition of the microbiome. Still, the role of the microbiome in the pathogenesis of this condition remains largely undefined.

APPROACH AND RESULTS

To address this, we have used two experimental models, administering alpha-naphtylisocyanate or feeding a 0.1% 3,5-diethoxycarbonyl-1,4-dihydrocollidine diet, to induce cholestatic liver disease in germ-free mice and germ-free mice conventionalized with the microbiome from wild-type, specific pathogen-free animals. Next, we have inhibited macrophage activation by depleting these cells using clodronate liposomes and inhibiting the inflammasome with a specific inhibitor of NOD-, LRR-, and pyrin domain-containing protein 3. Our results demonstrate that cholestasis, the accumulation of bile acids in the liver, fails to promote liver injury in the absence of the microbiome in vivo. Additional in vitro studies supported that endotoxin sensitizes hepatocytes to bile-acid-induced cell death. We also demonstrate that during cholestasis, macrophages contribute to promoting intestinal permeability and to altered microbiome composition through activation of the inflammasome, overall leading to increased endotoxin flux into the cholestatic liver.

CONCLUSIONS

We demonstrate that the intestinal microbiome contributes to cholestasis-mediated cell death and inflammation through mechanisms involving activation of the inflammasome in macrophages.

Abnormal metabolic processes involved in the pathogenesis of non-alcoholic fatty liver disease (Review)

Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases and can lead to liver cirrhosis or liver cancer in severe cases. In recent years, the incidence of NAFLD has increased substantially. The trend has continued to increase and has become a key point of concern for health systems. NAFLD is often associated with metabolic abnormalities caused by increased visceral obesity, including insulin resistance, diabetes mellitus, hypertension, dyslipidemia, atherosclerosis and systemic microinflammation. Therefore, the pathophysiological mechanisms of NAFLD must be clarified to develop new drug treatment strategies. Recently, researchers have conducted numerous studies on the pathogenesis of NAFLD and have identified various important regulatory factors and potential molecular mechanisms, providing new targets and a theoretical basis for the treatment of NAFLD. However, the pathogenesis of NAFLD is extremely complex and involves the interrelationship and influence of multiple organs and systems. Therefore, the condition must be explored further. In the present review, the abnormal metabolic process, including glucose, lipid, amino acid, bile acid and iron metabolism are reviewed. It was concluded that NAFLD is associated with an imbalanced metabolic network that involves glucose, lipids, amino acids, bile acids and iron, and lipid metabolism is the core metabolic process. The current study aimed to provide evidence and hypotheses for research and clinical treatment of NAFLD.

The zonula occludens protein family regulates the hepatic barrier system in the murine liver

The hepatic barrier is indispensable for the physiological functions of the liver and is impaired under various pathological conditions. Tight junctions reportedly play a central role in hepatic barrier regulation; however, there is limited direct evidence supporting this observation, with few in vivo models or confirmations of the implicated molecular mechanisms presented to date. We inactivated the tight junction component gene, Tjp2/ZO-2, and the related molecule, Tjp1/ZO-1, in mouse livers. In humans, TJP2/ZO-2 mutations have been implicated in the development of human progressive familial intrahepatic cholestasis 4 (PFIC4). The mice deficient in either ZO-1 or ZO-2 in the liver did not exhibit major abnormalities. However, the ablation of both molecules impaired the molecular architecture as well as the structure and function of hepatocyte tight junctions, which disrupted the hepatic barrier and was lethal to the mice by 6 weeks of age. In mutant mice, bile canaliculus formation and cellular polarity were compromised; also, transporter expression and localization were deregulated. Moreover, typical hepatic zonation and bile duct formation were inhibited, and sinusoidal vessels were disorganized. These findings clarify the role of tight junctions and polarity in the hepatic barrier as well as the effect that their disruption has on liver tissue. The observations also suggest that liver-specific ZO-1^-/- and ZO-2^-/- mice could be used as models for PFIC4, and this will provide new insights into liver pathophysiology and clinical applications.

Live Imaging of Innate and Adaptive Immune Responses in the Liver

Immune response in the liver is determined by the spatial organization and cellular dynamics of hepatic immune cells. The liver vasculature accommodates abundant tissue-resident innate immune cells, such as Kupffer cells, natural killer cells, and natural killer T cells, to ensure efficient intravascular immunosurveillance. The fenestrated sinusoids also allow direct contact between circulating T cells and non-canonical antigen-presenting cells, such as hepatocytes, to instruct adaptive immune responses. Distinct cellular behaviors are exploited by liver immune cells to exert proper functions. Intravital imaging enables real-time visualization of individual immune cell in living animals, representing a powerful tool in dissecting the spatiotemporal features of intrahepatic immune cells during steady state and liver diseases. This review summarizes current advances in liver immunology prompted by in vivo imaging, with a particular focus on liver-resident innate immune cells and hepatic T cells.

Drag-reducing polymers improve hepatic vaso-occlusion in SCD mice

Nanomolar concentrations of drag-reducing polymer (DRP) reduce vaso-occlusion in the liver of sickle cell disease (SCD) mice. The potential for DRP as a rheology-based treatment/therapy for SCD warrants further study.

Qiang-Gan formula extract improves non-alcoholic steatohepatitis via regulating bile acid metabolism and gut microbiota in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Qiang-Gan formula is a traditional Chinese medicine formula, which has been widely used in treating liver diseases in China.

AIM OF THE STUDY

To investigate the effect of Qiang-Gan formula extract (QGE) on non-alcoholic steatohepatitis (NASH) and its underlying possible mechanisms.

MATERIALS AND METHODS

The high-performance liquid chromatography finger-print method was used for the quality control of chemical components in QGE. Methionine- and choline-deficient diet-induced NASH mice were administrated with QGE via gavage for four weeks. Phenotypic parameters including liver histological change as well as serum levels of alanine transaminase (ALT), aspartate transaminase (AST) were detected. Bile acid profile in the serum, liver and fecal samples was analyzed by gas chromatography-mass spectrometer technique, and fecal microbiota was detected by 16S rDNA sequencing. Expression of liver G protein-coupled bile acid receptor 1 (TGR5), farnesiod X receptor (FXR), tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β) as well as molecules in nuclear factor kappa B (NF-κB) pathway was assayed by immunohistochemistry staining, RT-qPCR, or Western blot, respectively.

RESULTS

QGE alleviated liver inflammation, reduced serum ALT and AST levels and liver TNF-α and IL-1β expression in NASH mice. It also decreased liver and serum BA concentration and increased fecal lithocholicacid (LCA) production in this animal model. QGE altered the structure of gut microbiota, predominantly increased LCA-producing bacteria Bacteroides and Clostridium in NASH mice. In addition, the expression of liver TGR5 but not FXR was increased, and the molecules in NF-κB pathway were decreased in QGE-treated NASH mice.

CONCLUSIONS

QGE was effective in preventing NASH, possibly by regulation of gut microbiota-mediated LCA production, promotion of TGR5 expression and suppression of the NF-κB activation.

Disruption of FGF Signaling Ameliorates Inflammatory Response in Hepatic Stellate Cells

It is a well-documented event that fibroblast growth factors (FGFs) regulate liver development and homeostasis in autocrine, paracrine, and endocrine manners via binding and activating FGF receptors (FGFRs) tyrosine kinase in hepatocytes. Recent research reveals that hepatic stellate cells (HSCs) play a fundamental role in liver immunology. However, how FGF signaling in HSCs regulates liver inflammation remains unclear. Here, we report that FGF promoted NF-κB signaling, an inflammatory pathway, in human HSCs, which was associated with FGFR1 expression. Both FGF and NF-κB signaling in HSCs were compromised by FGFR1 tyrosine kinase inhibitor. After stimulating HSCs with proinflammatory cytokines, expression of multiple FGF ligands was significantly increased. However, disruption of FGF signaling with FGFR inhibitors prominently reduced the apoptosis, inflammatory response, NF-κB nuclear translocation, and expression of matrix metalloproteinase-9 (MMP-9) induced by TNFα in HSCs. Interestingly, FGF21 significantly alleviated the inflammation responses in the concanavalin A (Con A)-induced acutely injured liver. Unlike canonic FGFs that elicit signals through activating the FGFR–heparan sulfate complex, FGF21 activates the FGFR–KLB complex and elicits a different set of signals. Therefore, the finding here indicates the urgency of developing pathway-specific inhibitors that only suppress canonical FGF, but not non-canonical FGF21, signaling for alleviating inflammation in the liver, which is presented in all stages of diseased liver.

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

BACKGROUND

EDP-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.

METHODS

EDP-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.

RESULTS

In 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.

CONCLUSIONS

EDP-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.

The protective effect of obeticholic acid on lipopolysaccharide-induced disorder of maternal bile acid metabolism in pregnant mice

The disorder of bile acid metabolism is a common feature during pregnancy, which leads to adverse birth outcomes and maternal damage effects. However, the cause and therapy about the disorder of bile acid metabolism are still poor. Microbial infection often occurs in pregnant women, which can induce the disorder of bile acid metabolism in adult mice. Here, this study observed the acute effect of lipopolysaccharide (LPS) on maternal bile acid of pregnant mice at gestational day 17 and the protective effect of obeticholic acid (OCA) pretreatment, a potent agonist of bile acid receptor farnesoid X receptor (FXR). The results showed LPS significantly increased the level of maternal serum and disordered bile acids components of maternal serum and liver, which were ameliorated by OCA pretreatment with obviously reducing the contents of CA, TCA, DCA, TCDCA, CDCA, GCA and TDCA in maternal serum and DCA, TCA, TDCA, TUDCA, CDCA and TCDCA in maternal liver. Furthermore, we investigated the effects of OCA on LPS-disrupted bile acid metabolism in maternal liver. LPS disrupted maternal bile acid profile by decreasing transport and metabolism with hepatic tight junctions of bile acid in pregnant mice. OCA obviously increased the protein level of nuclear FXR and regulated its target genes involving in the metabolism of bile acid, which was characterized by the lower expression of bile acid synthase CYP7A1, the higher expression of CYP3A and the higher mRNA level of transporter Mdr1a/b. This study provided the evidences that LPS disrupted bile acid metabolism in the late stage of pregnant mice and OCA pretreatment played the protective role on it by activating FXR.

Tight Junction Proteins and the Biology of Hepatobiliary Disease

Tight junctions (TJ) are intercellular adhesion complexes on epithelial cells and composed of integral membrane proteins as well as cytosolic adaptor proteins. Tight junction proteins have been recognized to play a key role in health and disease. In the liver, TJ proteins have several functions: they contribute as gatekeepers for paracellular diffusion between adherent hepatocytes or cholangiocytes to shape the blood-biliary barrier (BBIB) and maintain tissue homeostasis. At non-junctional localizations, TJ proteins are involved in key regulatory cell functions such as differentiation, proliferation, and migration by recruiting signaling proteins in response to extracellular stimuli. Moreover, TJ proteins are hepatocyte entry factors for the hepatitis C virus (HCV)—a major cause of liver disease and cancer worldwide. Perturbation of TJ protein expression has been reported in chronic HCV infection, cholestatic liver diseases as well as hepatobiliary carcinoma. Here we review the physiological function of TJ proteins in the liver and their implications in hepatobiliary diseases.

Liver Progenitors and Adult Cell Plasticity in Hepatic Injury and Repair: Knowns and Unknowns

The liver is a complex organ performing numerous vital physiological functions. For that reason, it possesses immense regenerative potential. The capacity for repair is largely attributable to the ability of its differentiated epithelial cells, hepatocytes and biliary epithelial cells, to proliferate after injury. However, in cases of extreme acute injury or prolonged chronic insult, the liver may fail to regenerate or do so suboptimally. This often results in life-threatening end-stage liver disease for which liver transplantation is the only effective treatment. In many forms of liver injury, bipotent liver progenitor cells are theorized to be activated as an additional tier of liver repair. However, the existence, origin, fate, activation, and contribution to regeneration of liver progenitor cells is hotly debated, especially since hepatocytes and biliary epithelial cells themselves may serve as facultative stem cells for one another during severe liver injury. Here, we discuss the evidence both supporting and refuting the existence of liver progenitor cells in a variety of experimental models. We also debate the validity of developing therapies harnessing the capabilities of these cells as potential treatments for patients with severe and chronic liver diseases.

Vasoactive Intestinal Peptide Derived From Liver Mesenchymal Cells Mediates Tight Junction Assembly in Mouse Intrahepatic Bile Ducts

Formation of intrahepatic bile ducts (IHBDs) proceeds in accordance with their microenvironment. Particularly, mesenchymal cells around portal veins regulate the differentiation and ductular morphogenesis of cholangiocytes in the developing liver; however, further studies are needed to fully understand the arrangement of IHBDs into a continuous hierarchical network. This study aims to clarify the interaction between biliary and liver mesenchymal cells during IHBD formation. To identify candidate factors contributing to this cell–cell interaction, mesenchymal cells were isolated from embryonic day 16.5 matrix metalloproteinase 14 (MMP14)‐deficient (knockout [KO]) mice livers, in which IHBD formation is retarded, and compared with those of the wild type (WT). WT mesenchymal cells significantly facilitated the formation of luminal structures comprised of hepatoblast‐derived cholangiocytes (cholangiocytic cysts), whereas MMP14‐KO mesenchymal cells failed to promote cyst formation. Comprehensive analysis revealed that expression of vasoactive intestinal peptide (VIP) was significantly suppressed in MMP14‐KO mesenchymal cells. VIP and VIP receptor 1 (VIPR1) were mainly expressed in periportal mesenchymal cells and cholangiocytic progenitors during IHBD development, respectively, in vivo. VIP/VIPR1 signaling significantly encouraged cholangiocytic cyst formation and up‐regulated tight junction protein 1, cystic fibrosis transmembrane conductance regulator, and aquaporin 1, in vitro. VIP antagonist significantly suppressed the tight junction assembly and the up‐regulation of ion/water transporters during IHBD development in vivo. In a cholestatic injury model of adult mice, exogenous VIP administration promoted the restoration of damaged tight junctions in bile ducts and improved hyperbilirubinemia. Conclusion: VIP is produced by periportal mesenchymal cells during the perinatal stage. It supports bile duct development by establishing tight junctions and up‐regulating ion/water transporters in cholangiocytes. VIP contributes to prompt recovery from cholestatic damage through the establishment of tight junctions in the bile ducts.

Industrial, Biocide, and Cosmetic Chemical Inducers of Cholestasis

A frequent side effect of many drugs includes the occurrence of cholestatic liver toxicity. Over the past couple of decades, drug-induced cholestasis has gained considerable attention, resulting in a plethora of data regarding its prevalence and mechanistic basis. Likewise, several food additives and dietary supplements have been reported to cause cholestatic liver insults in the past few years. The induction of cholestatic hepatotoxicity by other types of chemicals, in particular synthetic compounds, such as industrial chemicals, biocides, and cosmetic ingredients, has been much less documented. Such information can be found in occasional clinical case reports of accidental intake or suicide attempts as well as in basic and translational study reports on mechanisms or testing of new therapeutics in cholestatic animal models. This paper focuses on such nonpharmaceutical and nondietary synthetic chemical inducers of cholestatic liver injury, in particular alpha-naphthylisocyanate, 3,5-diethoxycarbonyl-1,4-dihydrocollidine, methylenedianiline, paraquat, tartrazine, triclosan, 2-octynoic acid, and 2-nonynoic acid. Most of these cholestatic compounds act by similar mechanisms. This could open perspectives for the prediction of cholestatic potential of chemicals.

Invasive Ductular Reaction Operates Hepatobiliary Junctions upon Hepatocellular Injury in Rodents and Humans

Ductular reaction (DR) is observed in virtually all liver diseases in both humans and rodents. Depending on the injury, DR is confined within the periportal area or invades the parenchyma. On severe hepatocellular injury, invasive DR has been proposed to arise for supplying the liver with new hepatocytes. However, experimental data evidenced that DR contribution to hepatocyte repopulation is at the most modest, unless replicative capacity of hepatocytes is abrogated. Herein, we proposed that invasive DR could contribute to operating hepatobiliary junctions on hepatocellular injury. The choline-deficient ethionine-supplemented mouse model of hepatocellular injury and human liver samples were used to evaluate the hepatobiliary junctional role of the invasive form of DR. Choline-deficient ethionine-supplemented-induced DR expanded as biliary epithelium into the lobule and established new junctions with the canaliculi. By contrast, no new ductular-canalicular junctions were observed in mouse models of biliary obstructive injury exhibiting noninvasive DR. Similarly, in humans, an increased number of hepatobiliary junctions were observed in hepatocellular diseases (viral, drug induced, or metabolic) in which DR invaded the lobule but not in biliary diseases (obstruction or cholangitis) in which DR was contained within the portal mesenchyme. In conclusion, our data in rodents and humans support that invasive DR plays a hepatobiliary junctional role to maintain structural continuity between hepatocytes and ducts in disorders affecting hepatocytes.