Fibrotic Events in the Progression of Cholestatic Liver Disease

Liver Fibrosis: From Basic Science towards Clinical Progress, Focusing on the Central Role of Hepatic Stellate Cells

The burden of chronic liver disease is globally increasing at an alarming rate. Chronic liver injury leads to liver inflammation and fibrosis (LF) as critical determinants of long-term outcomes such as cirrhosis, liver cancer, and mortality. LF is a wound-healing process characterized by excessive deposition of extracellular matrix (ECM) proteins due to the activation of hepatic stellate cells (HSCs). In the healthy liver, quiescent HSCs metabolize and store retinoids. Upon fibrogenic activation, quiescent HSCs transdifferentiate into myofibroblasts; lose their vitamin A; upregulate α-smooth muscle actin; and produce proinflammatory soluble mediators, collagens, and inhibitors of ECM degradation. Activated HSCs are the main effector cells during hepatic fibrogenesis. In addition, the accumulation and activation of profibrogenic macrophages in response to hepatocyte death play a critical role in the initiation of HSC activation and survival. The main source of myofibroblasts is resident HSCs. Activated HSCs migrate to the site of active fibrogenesis to initiate the formation of a fibrous scar. Single-cell technologies revealed that quiescent HSCs are highly homogenous, while activated HSCs/myofibroblasts are much more heterogeneous. The complex process of inflammation results from the response of various hepatic cells to hepatocellular death and inflammatory signals related to intrahepatic injury pathways or extrahepatic mediators. Inflammatory processes modulate fibrogenesis by activating HSCs and, in turn, drive immune mechanisms via cytokines and chemokines. Increasing evidence also suggests that cellular stress responses contribute to fibrogenesis. Recent data demonstrated that LF can revert even at advanced stages of cirrhosis if the underlying cause is eliminated, which inhibits the inflammatory and profibrogenic cells. However, despite numerous clinical studies on plausible drug candidates, an approved antifibrotic therapy still remains elusive. This state-of-the-art review presents cellular and molecular mechanisms involved in hepatic fibrogenesis and its resolution, as well as comprehensively discusses the drivers linking liver injury to chronic liver inflammation and LF.

Molecular basis of progressive familial intrahepatic cholestasis 3. A proteomics study

Progressive familial intrahepatic cholestasis type 3 (PFIC3) is a severe rare liver disease that affects between 1/50,000 and 1/100,000 children. In physiological conditions, bile is produced by the liver and stored in the gallbladder, and then it flows to the small intestine to play its role in fat digestion. To prevent tissue damage, bile acids (BAs) are kept in phospholipid micelles. Mutations in phosphatidyl choline transporter ABCB4 (MDR3) lead to intrahepatic accumulation of free BAs that result in liver damage. PFIC3 onset usually occurs at early ages, progresses rapidly, and the prognosis is poor. Currently, besides the palliative use of ursodeoxycholate, the only available treatment for this disease is liver transplantation, which is really challenging for short-aged patients. To gain insight into the pathogenesis of PFIC3 we have performed an integrated proteomics and phosphoproteomics study in human liver samples to then validate the emerging functional hypotheses in a PFIC3 murine model. We identified 6246 protein groups, 324 proteins among them showing differential expression between control and PFIC3. The phosphoproteomic analysis allowed the identification of 5090 phosphopeptides, from which 215 corresponding to 157 protein groups, were differentially phosphorylated in PFIC3, including MDR3. Regulation of essential cellular processes and structures, such as inflammation, metabolic reprogramming, cytoskeleton and extracellular matrix remodeling, and cell proliferation, were identified as the main drivers of the disease. Our results provide a strong molecular background that significantly contributes to a better understanding of PFIC3 and provides new concepts that might prove useful in the clinical management of patients.

Progress in the Management of Patients with Cholestatic Liver Disease: Where Are We and Where Are We Going?

Cholestatic liver disease is a group of diseases in which bile acid accumulates in the liver for various reasons, resulting in abnormal liver biochemical indicators and histological damage. Cholestasis can be divided into intrahepatic cholestasis and extrahepatic cholestasis, which will contribute to liver damage and progress to liver fibrosis and cirrhosis. Primary biliary cholangitis (PBC) and primary sclerosing cholangitis are the two most typical cholestatic liver diseases. Ursodeoxycholic acid is currently the first-line treatment for PBC, while obeticholic acid, budesonide and fibrates have also shown good potential in the treatment of PBC. There are currently no official drugs approved to treat primary sclerosing cholangitis, and the use of ursodeoxycholic acid may have certain clinical benefits. At present, progress has been made in new treatment directions for cholestatic liver disease, including fibroblast growth factor 19, cholestyramine, S-adenosyl-L-methionine, steroid drugs, farnesoid X receptor agonists, and more. Considerable progress has been made in the management of cholestatic liver disease but there are still many opportunities and challenges. In this review, we summarized the recommended guidelines for the management of cholestatic disease and the progress of new drug research and development, in order to provide an important reference for the clinical practice of cholestatic liver disease.

RNA-binding protein transcripts as potential biomarkers for detecting Primary Sclerosing Cholangitis and for predicting its progression to Cholangiocarcinoma

Primary Sclerosing Cholangitis (PSC) is a persistent inflammatory liver condition that affects the bile ducts and is commonly diagnosed in young individuals. Despite efforts to incorporate various clinical, biochemical and molecular parameters for diagnosing PSC, it remains challenging, and no biomarkers characteristic of the disease have been identified hitherto. PSC is linked with an uncertain prognosis, and there is a pressing need to explore multiomics databases to establish a new biomarker panel for the early detection of PSC's gradual progression into Cholangiocarcinoma (CCA) and for the development of effective therapeutic interventions. Apart from non-coding RNAs, other components of the Ribonucleoprotein (RNP) complex, such as RNA-Binding Proteins (RBPs), also hold great promise as biomarkers due to their versatile expression in pathological conditions. In the present review, an update on the RBP transcripts that show dysregulated expression in PSC and CCA is provided. Moreover, by utilizing a bioinformatic data mining approach, we give insight into those RBP transcripts that also exhibit differential expression in liver and gall bladder, as well as in body fluids, and are promising as biomarkers for diagnosing and predicting the prognosis of PSC. Expression data were bioinformatically extracted from public repositories usingTCGA Bile Duct Cancer dataset for CCA and specific NCBI GEO datasets for both PSC and CCA; more specifically, RBPs annotations were obtained from RBP World database. Interestingly, our comprehensive analysis shows an elevated expression of the non-canonical RBPs, FANCD2, as well as the microtubule dynamics regulator, ASPM, transcripts in the body fluids of patients with PSC and CCA compared with their respective controls, with the same trend in expression being observed in gall bladder and liver cancer tissues. Consequently, the manipulation of tissue expression of RBP transcripts might be considered as a strategy to mitigate the onset of CCA in PSC patients, and warrants further experimental investigation. The analysis performed herein may be helpful in the identification of non-invasive biomarkers for the early detection of PSC and for predicting its progression into CCA. In conclusion, future clinical research should investigate in more depth the full potential of RBP transcripts as biomarkers for human pathologies.

Farnesoid X receptor modulator 12β-(m-methyl-benzoyl)-11,12-dihydro oleanolic acid represses liver fibrosis by inhibiting ERK/p38 signaling pathways

Liver fibrosis is a common pathological process in the progression of several chronic liver diseases to cirrhosis and hepatocellular carcinoma. Therefore, the development of medications that can repress the progress of liver fibrosis is essential. We discovered that initially, 12β-(m-methyl-benzoyl)-11,12-dihydro oleanolic acid (12d-OA), a farnesoid X receptor (FXR) modulator, possessed potential anti-fibrotic properties. Through an in-depth study, we revealed that 12d-OA not only inhibited the expression of fibrogenic markers in the LX-2 cells and HSC-T6 cells but also exhibited significant protective effects against liver injury and liver fibrosis in bile duct ligation (BDL) rats. Further exploration of its molecular mechanism indicated that 12d-OA exerted antifibrotic activity by inhibiting the extracellular signal-regulated kinase (ERK)/stress-activated protein kinase (p38) signaling pathways. Consequently, the great effects of 12d-OA in vitro and in vivo suggest that it may be a good candidate for liver fibrosis.

Molecular insights into experimental models and therapeutics for cholestasis

Cholestatic liver disease (CLD) is a range of conditions caused by the accumulation of bile acids (BAs) or disruptions in bile flow, which can harm the liver and bile ducts. To investigate its pathogenesis and treatment, it is essential to establish and assess experimental models of cholestasis, which have significant clinical value. However, owing to the complex pathogenesis of cholestasis, a single modelling method can merely reflect one or a few pathological mechanisms, and each method has its adaptability and limitations. We summarize the existing experimental models of cholestasis, including animal models, gene-knockout models, cell models, and organoid models. We also describe the main types of cholestatic disease simulated clinically. This review provides an overview of targeted therapy used for treating cholestasis based on the current research status of cholestasis models. In addition, we discuss the respective advantages and disadvantages of different models of cholestasis to help establish experimental models that resemble clinical disease conditions. In sum, this review not only outlines the current research with cholestasis models but also projects prospects for clinical treatment, thereby bridging basic research and practical therapeutic applications.

Uncovering a Novel Functional Interaction Between Adult Hepatic Progenitor Cells, Inflammation and EGFR Signaling During Bile Acids-Induced Injury

Chronic cholestatic damage is associated to both accumulation of cytotoxic levels of bile acids and expansion of adult hepatic progenitor cells (HPC) as part of the ductular reaction contributing to the regenerative response. Here, we report a bile acid-specific cytotoxic response in mouse HPC, which is partially impaired by EGF signaling. Additionally, we show that EGF synergizes with bile acids to trigger inflammatory signaling and NLRP3 inflammasome activation in HPC. Aiming at understanding the impact of this HPC specific response on the liver microenvironment we run a proteomic analysis of HPC secretome. Data show an enrichment in immune and TGF-β regulators, ECM components and remodeling proteins in HPC secretome. Consistently, HPC-derived conditioned medium promotes hepatic stellate cell (HSC) activation and macrophage M1-like polarization. Strikingly, EGF and bile acids co-treatment leads to profound changes in the secretome composition, illustrated by an abolishment of HSC activating effect and by promoting macrophage M2-like polarization. Collectively, we provide new specific mechanisms behind HPC regulatory action during cholestatic liver injury, with an active role in cellular interactome and inflammatory response regulation. Moreover, findings prove a key contribution for EGFR signaling jointly with bile acids in HPC-mediated actions.

Hydrostatic pressure mediates epithelial-mesenchymal transition of cholangiocytes through RhoA/ROCK and TGF-β/smad pathways

Biomechanical cue within the tissue microenvironment is known to play a critical role in regulating cell behaviors and maintaining tissue homeostasis. As hydrostatic pressure often increases in biliary system under pathological states, we investigated the effect of the moderate elevation of the hydrostatic pressure on biliary epithelial cells, especially on the epithelial-mesenchymal transition (EMT). Human intrahepatic biliary epithelial cells were loaded to hydrostatic pressure using a commercial device. We found that loading the cells to 50 mmHg hydrostatic pressure induced obvious morphological changes and significantly upregulated vimentin, ZEB1, and pSmad2/3, fibronectin, and collagen 1α. All changes induced by hydrostatic pressure loading were effectively mitigated by either ROCK inhibitor (Y-27632) or ALK5 inhibitor (SB-431542). Our in vitro experimental data suggests that hydrostatic pressure loading induces EMT of cholangiocytes through RhoA/ROCK and TGF-β/Smad pathways. Elevated hydrostatic pressure in biliary duct system under pathological states may promote the biliary epithelial cells shifting to profibrotic and mesenchymal characteristics.

Elucidation of pericholangitis and periductal fibrosis in cholestatic liver diseases via extracellular vesicles released by polarized biliary epithelial cells

Cholestatic liver diseases causes inflammation and fibrosis around bile ducts. However, the pathological mechanism has not been elucidated. Extracellular vesicles (EVs) are released from both the basolateral and apical sides of polarized biliary epithelial cells. We aimed to investigate the possibility that EVs released from the basolateral sides of biliary epithelial cells by bile acid stimulation induce inflammatory cells and fibrosis around bile ducts, and they may be involved in the pathogenesis of cholestatic liver disease. Human biliary epithelial cells (H69) were grown on cell culture inserts and stimulated with chenodeoxycholic acid + IFN-γ. Human THP-1-derived M1-macrophages, LX-2 cells, and KMST-6 cells were treated with the extracted basolateral EVs, and inflammatory cytokines and fibrosis markers were detected by RT-PCR. Highly expressed proteins from stimulated EVs were identified, and M1-macrophages, LX-2, KMST-6 were treated with these recombinant proteins. Stimulated EVs increased the expression of TNF, IL-1β, and IL-6 in M1-macrophages, TGF-β in LX-2 and KMST-6 compared with the corresponding expression levels in unstimulated EVs. Nucleophosmin, nucleolin, and midkine levels were increased in EVs from stimulated cells compared with protein expression in EVs from unstimulated cells. Leukocyte cell-derived chemotaxin-2 (LECT2) is highly expressed only in EVs from stimulated cells. Stimulation of M1-macrophages with recombinant nucleophosmin, nucleolin, and midkine significantly increased the expression of inflammatory cytokines. Stimulation of LX-2 and KMST-6 with recombinant LECT2 significantly increased the expression of fibrotic markers. These results suggest that basolateral EVs are related to the development of pericholangitis and periductal fibrosis in cholestatic liver diseases.NEW & NOTEWORTHY Our research elucidated that the composition of basolateral EVs from the biliary epithelial cells changed under bile acid exposure and the basolateral EVs contained the novel inflammation-inducing proteins NPM, NCL, and MK and the fibrosis-inducing protein LECT2. We report that these new results are possible to lead to the potential therapeutic target of cholestatic liver diseases in the future.

Ursodeoxycholic acid and 18β-glycyrrhetinic acid alleviate ethinylestradiol-induced cholestasis via downregulating RORγt and CXCR3 signaling pathway in iNKT cells

Estrogen-induced intrahepatic cholestasis (IHC) is a mild but potentially serious risk and urges for new therapeutic targets and effective treatment. Our previous study demonstrated that RORγt and CXCR3 signaling pathway of invariant natural killer T (iNKT) 17 cells play pathogenic roles in 17α-ethinylestradiol (EE)-induced IHC. Ursodeoxycholic acid (UDCA) and 18β-glycyrrhetinic acid (GA) present a protective effect on IHC partially due to their immunomodulatory properties. Hence in present study, we aim to investigate the effectiveness of UDCA and 18β-GA in vitro and verify the accessibility of the above targets. Biochemical index measurement indicated that UDCA and 18β-GA presented efficacy to alleviate EE-induced cholestatic cytotoxicity. Both UDCA and 18β-GA exhibited suppression on the CXCL9/10-CXCR3 axis, and significantly restrained the expression of RORγt in vitro. In conclusion, our observations provide new therapeutic targets of UDCA and 18β-GA, and 18β-GA as an alternative treatment for EE-induced cholestasis.

Gardenia extract protects against intrahepatic cholestasis by regulating bile acid enterohepatic circulation

ETHNOPHARMACOLOGICAL RELEVANCE

Cholestasis is the main manifestation of cholestatic liver disease, which has a risk of progression to end-stage liver disease. Gardeniae Fructus is the dried fruit of Gardeniae jasminoides Ellis, a plant of the Rubiaceae family. Gardeniae Fructus has shown therapeutic potential in cholestasis-related liver diseases and it is generally believed that Gardeniae Fructus ameliorates cholestasis, which could be related to its influence on bile acids (BAs) metabolism. However, the specific targets of Gardeniae Fructus and its impact on enterohepatic circulation of BAs have not yet been fully elucidated.

AIM OF THE STUDY

To systematically elucidate the mechanism by which Gardenia extract (GE, total iridoids in Gardeniae Fructus, which contains the predominant and characteristic phytoconstituents of Gardeniae Fructus) ameliorates alpha-naphthylisothiocyanate (ANIT)-induced cholestatic liver injury.

MATERIALS AND METHODS

Sprague-Dawley rats were orally administered water, obeticholic acid (OCA, 2 mg/kg), or GE (21 and 42 mg/kg) once daily for five days. On the third day, the model was established by administration of a single dose of ANIT (40 mg/kg) by oral gavage. Biochemical and pathological analyses, BA metabolomics, transcriptomics, and qRT-PCR were performed.

RESULTS

The profile of BAs in serum and liver confirmed that GE attenuated ANIT-induced acute cholestasis by affecting BA metabolism in a dose-dependent manner. Liver transcriptomic analysis indicated that GE mainly influenced the primary bile acid (PBA) biosynthesis and bile secretion pathways. GE mainly affected PBA biosynthesis in liver by upregulating Cyp8b1 gene expression, thereby significantly reducing the level of total bile acids (TBA). GE mainly promoted PBA excretion from liver into duodenum by upregulating Fxr and Oatp1 gene expression, thereby increasing the excretion of PBA in feces, and inhibiting PBA in liver entering the blood by alternative routes to reduce TBA levels in serum and urine and improve the enterohepatic circulation of BAs.

CONCLUSION

GE attenuated ANIT-induced hepatotoxicity and cholestasis in rats by upregulating Cyp8b1 expression to inhibit BA synthesis in the liver, while also promoting BA excretion via the intestinal-fecal route, and improving enterohepatic circulation of BAs.

The Role of CCL24 in Primary Sclerosing Cholangitis: Bridging Patient Serum Proteomics to Preclinical Data

Primary sclerosing cholangitis (PSC) is an inflammatory and fibrotic biliary disease lacking approved treatment. We studied CCL24, a chemokine shown to be overexpressed in damaged bile ducts, and its involvement in key disease-related mechanisms. Serum proteomics of PSC patients and healthy controls (HC) were analyzed using the Olink® proximity extension assay and compared based on disease presence, fibrosis severity, and CCL24 levels. Disease-related canonical pathways, upstream regulators, and toxicity functions were elevated in PSC patients compared to HC and further elevated in patients with high CCL24 levels. In vitro, a protein signature in CCL24-treated hepatic stellate cells (HSCs) differentiated patients by disease severity. In mice, CCL24 intraperitoneal injection selectively recruited neutrophils and monocytes. Treatment with CM-101, a CCL24-neutralizing antibody, in an α-naphthylisothiocyanate (ANIT)-induced cholestasis mouse model effectively inhibited accumulation of peribiliary neutrophils and macrophages while reducing biliary hyperplasia and fibrosis. Furthermore, in PSC patients, CCL24 levels were correlated with upregulation of monocyte and neutrophil chemotaxis pathways. Collectively, these findings highlight the distinct role of CCL24 in PSC, influencing disease-related mechanisms, affecting immune cells trafficking and HSC activation. Its blockade with CM-101 reduces inflammation and fibrosis and positions CCL24 as a promising therapeutic target in PSC.

Astragalus saponins protect against extrahepatic and intrahepatic cholestatic liver fibrosis models by activation of farnesoid X receptor

ETHNOPHARMACOLOGICAL RELEVANCE

Cholestatic Liver Fibrosis (CLF) is a hepatobiliary disease that typically arises as a late-stage complication of cholestasis, which can have multiple underlying causes. There are no satisfactory chemical or biological drugs for CLF. Total Astragalus saponins (TAS) are considered to be the main active constituents of the traditional Chinese herb Astragali Radix (AR), which has the obvious improvement effects for treating CLF. However, the mechanism of anti-CLF effects of TAS is still unclear.

AIM OF THE STUDY

The present study was undertaken to investigate the therapeutic effects of TAS against bile duct ligation (BDL) and 3, 5-diethoxycarbonyl-1,4-dihydroxychollidine (DDC) -induced CLF models and to reveal the potential mechanism to support its clinic use with scientific evidence.

MATERIALS AND METHODS

In this study, BDL-induced CLF rats were treated with TAS (20 mg/kg, 40 mg/kg) and DDC-induced CLF mice were treated with 56 mg/kg TAS. The therapeutic effects of TAS on extrahepatic and intrahepatic CLF models were evaluated by serum biochemical analysis, liver histopathology and hydroxyproline (Hyp). Thirty-nine individual bile acids (BAs) in serum and liver were quantified by using UHPLC-Q-Exactive Orbitrap HRMS. qRT-PCR, Western blot and immunohistochemistry analysis were used to measure the expression of liver fibrosis and ductular reaction markers, inflammatory factors and BAs related metabolic transporters, along with nuclear receptor farnesoid X receptor (FXR).

RESULTS

The serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total bilirubin (TBiL), direct bilirubin (DBiL) and contents of liver Hyp were dose-dependently improved after treatment for TAS in BDL and DDC- induced CLF models. And the increased levels of ALT and AST were significantly improved by total extract from Astragali radix (ASE) in BDL model. The liver fibrosis and ductular reaction markers, α-smooth muscle actin (α-SMA) and cytokeratin 19 (CK19), were significantly ameliorated in TAS group. And the liver expression of inflammatory factors: interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β) were significantly decreased after TAS treatment. In addition, TAS significantly ameliorated taurine-conjugated BAs (tau-BAs) levels, particularly α-TMCA, β-TMCA and TCA contents in serum and liver, which correlated with induced expressions of hepatic FXR and BAs secretion transporters. Furthermore, TAS significantly improved short heterodimer partner (SHP), cholesterol 7α-hydroxylase (Cyp7a1), Na+ taurocholate cotransport peptide (NTCP) and bile-salt export pump (BSEP) mRNA and protein expression.

CONCLUSIONS

TAS exerted a hepatoprotective effect against CLF by ameliorating liver injury, inflammation and restoring the altered tau-BAs metabolism to produce a positive regulatory effect on FXR-related receptors and transporters.

CsHscB Derived from a Liver Fluke Clonorchis sinensis Ameliorates Cholestatic Hepatic Fibrosis in a Mouse Model of Sclerosing Cholangitis

BACKGROUND

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease characterized by inflammatory fibrosis usually involving the whole biliary tree. However, there are very limited treatment options to treat this disease. Our previous study found a lipid-protein rCsHscB from a liver fluke - Clonorchis sinensis, which had full capacities of immune regulation. Therefore, we investigated the role of rCsHscB in a mouse model of sclerosing cholangitis induced by xenobiotic 3,5- diethoxycarbonyl-1,4-dihydrocollidine (DDC) to explore whether this protein had potential therapeutic value for PSC.

METHODS

Mice were fed 0.1% DDC for 4 weeks and treated with CsHscB (30 μg/mouse, intraperitoneal injection, once every 3 days); the control group was given an equal amount of PBS or CsHscB under normal diet conditions. All the mice were sacrificed at 4 weeks for the evaluation of biliary proliferation, fibrosis, and inflammation.

RESULTS

rCsHscB treatment attenuated DDC-induced liver congestion and enlargement and significantly decreased the upregulation of serum AST and ALT levels. The administration of rCsHscB to DDC-fed mice significantly decreased cholangiocyte proliferation and pro-inflammatory cytokine production compared to mice fed with DDC alone. Also, rCsHscB treatment showed a decreased expression of α-SMA in the liver and other markers of liver fibrosis (Masson staining, Hydroxyproline content, and collagen deposit). More interestingly, DDC-fed mice treated with rCsHscB showed a significant up-regulation of PPAR-γ expression, which was similar to control mice, indicating the involvement of PPAR-γ signaling in the protective action of rCsHscB.

CONCLUSION

Overall, our data show that rCsHscB attenuates the progression of cholestatic fibrosis induced by DDC and supports the potential for manipulating the parasite-derived molecule to treat certain immune-mediated disorders.

In Vivo and In Silico Studies of the Hepatoprotective Activity of Tert-Butylhydroquinone

Tert-butylhydroquinone (TBHQ) is a synthetic food antioxidant with biological activities, but little is known about its pharmacological benefits in liver disease. Therefore, this work aimed to evaluate TBHQ during acute liver damage induced by CCl4 (24 h) or BDL (48 h) in Wistar rats. It was found that pretreatment with TBHQ prevents 50% of mortality induced by a lethal dose of CCl4 (4 g/kg, i.p.), and 80% of BDL+TBHQ rats survived, while only 50% of the BDL group survived. Serum markers of liver damage and macroscopic and microscopic (H&E staining) observations suggest that TBHQ protects from both hepatocellular necrosis caused by the sublethal dose of CCl4 (1.6 g/kg, i.p.), as well as necrosis/ductal proliferation caused by BDL. Additionally, online databases identified 49 potential protein targets for TBHQ. Finally, a biological target candidate (Keap1) was evaluated in a proof-of-concept in silico molecular docking assay, resulting in an interaction energy of -5.5491 kcal/mol, which was higher than RA839 and lower than monoethyl fumarate (compounds known to bind to Keap1). These findings suggest that TBHQ increases the survival of animals subjected to CCl4 intoxication or BDL, presumably by reducing hepatocellular damage, probably due to the interaction of TBHQ with Keap1.

PGC1α deficiency reverses cholestasis-induced liver injury via attenuating hepatic inflammation and promoting bile duct remodeling

OBJECTIVES

Cholestatic liver diseases are characterized by hepatocellular damage, cholangiocyte proliferation, and progressive fibrosis. Bile duct ligation (BDL) is widely used to resemble liver injuries induced by cholestasis. Peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC1α) was reported to play a critical role in multiple biological responses. Nevertheless, whether PGC1α is involved in bile acid metabolism and biliary disorders remains unclear. This study aimed to investigate the effect of PGC1α on hepatic responses after cholestatic injury.

MATERIALS AND METHODS

Wild-type mice were subjected to BDL or sham surgery for 14 days and human liver specimens from patients with primary biliary cholangitis (PBC) were collected to detect the expression of PGC1α. Hepatic-specific PGC1α knockout mice (HKO) were constructed and subjected to BDL, in which the effects of PGC1α on cholestatic liver injury were demonstrated by biochemical and histopathological assessments, immunoblotting, and metabolomics.

RESULTS

The expression of PGC1α was upregulated in the liver of PBC patients and murine models. Both in vivo and in vitro experiments supported the protective effects of PGC1α on cholestasis-induced hepatocyte injury. Infiltrated inflammatory cells after BDL were decreased in HKO mice. Inhibited Wnt/β-Catenin pathway and enhanced Notch signaling promoted transdifferentiation of hepatic progenitor cells (HPC)/ hepatocytes into cholangiocytes, leading to the greater ductular reaction observed in the HKO mice. But bile acids metabolism and mitochondrial function were not affected due to hepatic PGC1α deficiency in cholestasis.

CONCLUSIONS

Hepatic-specific deletion of PGC1α regulated liver regeneration by promoting ductular reactions, thereby exerting protective effects against BDL-induced liver injury, which could be a new potential therapeutic target.

Autophagy and Senescence: The Molecular Mechanisms and Implications in Liver Diseases

The liver is the primary organ accountable for complex physiological functions, including lipid metabolism, toxic chemical degradation, bile acid synthesis, and glucose metabolism. Liver function homeostasis is essential for the stability of bodily functions and is involved in the complex regulation of the balance between cell proliferation and cell death. Cell proliferation-halting mechanisms, including autophagy and senescence, are implicated in the development of several liver diseases, such as cholestasis, viral hepatitis, nonalcoholic fatty liver disease, liver fibrosis, and hepatocellular carcinoma. Among various cell death mechanisms, autophagy is a highly conserved and self-degradative cellular process that recycles damaged organelles, cellular debris, and proteins. This process also provides the substrate for further metabolism. A defect in the autophagy machinery can lead to premature diseases, accelerated aging, inflammatory state, tumorigenesis, and cellular senescence. Senescence, another cell death type, is an active player in eliminating premalignant cells. At the same time, senescent cells can affect the function of neighboring cells by secreting the senescence-associated secretory phenotype and induce paracrine senescence. Autophagy can promote and delay cellular senescence under different contexts. This review decodes the roles of autophagy and senescence in multiple liver diseases to achieve a better understanding of the regulatory mechanisms and implications of autophagy and senescence in various liver diseases.

The zhuyu pill relieves rat cholestasis by regulating the mRNA expression of lipid and bile metabolism associated genes

Background: The Zhuyu pill (ZYP), composed of Coptis chinensis Franch. and Tetradium ruticarpum (A. Jussieu) T. G. Hartley, is an effective traditional Chinese medicine with potential anti-cholestatic effects. However, the underlying mechanisms of ZYP remain unknown. Objective: To investigate the mechanism underlying the interventional effect of ZYP on mRNA-seq analysis in cholestasis rat models. Materials and methods: This study tested the effects of a low-dose (0.6 g/kg) and high-dose (1.2 g/kg) of ZYP on a cholestasis rat model induced by α-naphthyl-isothiocyanate (ANIT, 50 mg/kg). Serum biochemistry and histopathology results were used to evaluate the therapeutic effect of ZYP, and mRNA-Seq analysis was performed and verified using real-time fluorescence quantitative PCR (qRT-PCR). GO, KEGG, and GSEA analyses were integrated to identify the mechanism by which ZYP impacted cholestatic rats. Results: ZYP was shown to significantly improve abnormal changes in the biochemical blood indexes and liver histopathology of cholestasis rats and regulate pathways related to bile and lipid metabolism, including fatty acid metabolism, retinol metabolism, and steroid hormone biosynthesis, to alleviate inflammation, cholestasis, and lipid metabolism disorders. Relative expression of the essential genes Cyp2a1, Ephx2, Acox2, Cyp1a2, Cyp2c11, and Sult2a1 was verified by qRT-PCR and showed the same trend as mRNA-seq analysis. Conclusion: ZYP has a significant anti-cholestatic effect by regulating bile metabolism and lipid metabolism related pathways. These findings indicate that ZYP is a novel and promising prospect for treating cholestasis.

Integrated 16 S rRNA gene sequencing and serum metabolomics approaches to decipher the mechanism of Qingre Lidan decoction in the treatment of cholestatic liver injury

BACKGROUND

Cholestasis is a commonly occurring disorder induced by impaired bile flow, for which there is no effective treatment so far. Qingre Lidan decoction (QRLD) is a clinically used herbal compound for the long-term treatment of bile circulation disorders arising from inflammation and obstruction in the gallbladder and bile ducts. The objective of this study was to investigate the protective effect of QRLD on cholestatic liver injury and its possible mechanism.

METHODS

α-Naphthyl isothiocyanate (ANIT) was used to induce cholestatic liver injury in rats. Liver histopathology and serum biochemical markers were used to assess QRLD's protective impact. The possible biomarkers and mechanism of the therapeutic benefits of QRLD were investigated using a UHPLC-based Q-Exactive Orbitrap MS / MS untargeted serum metabolomics technique together with 16 S rRNA microbiota profiling. Afterwards, using RT-qPCR as well as Western Blot techniques, the expression of pertinent indicators was determined.

RESULTS

The intervention effect of QRLD was stronger at medium and high dosages than at low doses, and it dramatically decreased the levels of serum biochemical markers in cholestatic rats reflecting alterations in liver function and relieving ANIT-induced abnormalities in the liver's histopathology. Serum metabolomics showed that QRLD could affect the metabolic profile of cholestatic rats, mainly related to glycerophospholipid metabolism, taurine and hypotaurine metabolism, alanine, aspartate and glutamate metabolism, and histidine metabolic pathway. Additionally, analysis of 16 S rRNA gene sequencing indicated that QRLD could moderate ANIT-induced microbiota disorders, particularly Romboutsia, Bifidobacterium, Fusicatenibacter, Prevotella_9, Prevotellaceae_NK3B31_group and Prevotella_1. Other experimental results showed that QRLD significantly upregulated the mRNA and protein expression of PPARα, CYP7A1 and NTCP in the liver, inhibited the expression of p-IκBα, p-p65 and TNFα while increasing the anti-inflammatory factor IL-10, and downregulated the expression of MDA (a peroxidation product) and D-lactic acid (an intestinal barrier indicator) while increasing the expression of SOD and GSH.

CONCLUSIONS

QRLD can effectively regulate endogenous metabolites and microbiota disorders in cholestatic rats that are correlated with the attenuation of inflammation and oxidative stress.

Targeting collagen homeostasis for the treatment of liver fibrosis: Opportunities and challenges

Liver fibrosis is an excessive production, aberrant deposition, and deficit degradation of extracellular matrix (ECM). Patients with unresolved fibrosis ultimately undergo end-stage liver diseases. To date, the effective and safe strategy to cease fibrosis progression remains an unmet clinical need. Since collagens are the most abundant ECM protein which play an essential role in fibrogenesis, the suitable regulation of collagen homeostasis could be an effective strategy for the treatment of liver fibrosis. Therefore, this review provides a brief overview on the dysregulation of ECM homeostasis, focusing on collagens, in the pathogenesis of liver fibrosis. Most importantly, promising therapeutic mechanisms related to biosynthesis, deposition and extracellular interactions, and degradation of collagens, together with preclinical and clinical antifibrotic evidence of drugs affecting each target are orderly criticized. In addition, challenges for targeting collagen homeostasis in the treatment of liver fibrosis are discussed.

Hypericum perforatum L. and the Underlying Molecular Mechanisms for Its Choleretic, Cholagogue, and Regenerative Properties

Any defects in bile formation, secretion, or flow may give rise to cholestasis, liver fibrosis, cirrhosis, and hepatocellular carcinoma. As the pathogenesis of hepatic disorders is multifactorial, targeting parallel pathways potentially increases the outcome of therapy. Hypericum perforatum has been famed for its anti-depressive effects. However, according to traditional Persian medicine, it helps with jaundice and acts as a choleretic medication. Here, we will discuss the underlying molecular mechanisms of Hypericum for its use in hepatobiliary disorders. Differentially expressed genes retrieved from microarray data analysis upon treatment with safe doses of Hypericum extract and intersection with the genes involved in cholestasis are identified. Target genes are located mainly at the endomembrane system with integrin-binding ability. Activation of α5β1 integrins, as osmo-sensors in the liver, activates a non-receptor tyrosine kinase, c-SRC, which leads to the insertion of bile acid transporters into the canalicular membrane to trigger choleresis. Hypericum upregulates CDK6 that controls cell proliferation, compensating for the bile acid damage to hepatocytes. It induces ICAM1 to stimulate liver regeneration and regulates nischarin, a hepatoprotective receptor. The extract targets the expression of conserved oligomeric Golgi (COG) and facilitates the movement of bile acids toward the canalicular membrane via Golgi-derived vesicles. In addition, Hypericum induces SCP2, an intracellular cholesterol transporter, to maintain cholesterol homeostasis. We have also provided a comprehensive view of the target genes affected by Hypericum's main metabolites, such as hypericin, hyperforin, quercitrin, isoquercitrin, quercetin, kaempferol, rutin, and p-coumaric acid to enlighten a new scope in the management of chronic liver disorders. Altogether, standard trials using Hypericum as a neo-adjuvant or second-line therapy in ursodeoxycholic-acid-non-responder patients define the future trajectories of cholestasis treatment with this product.

Selected Aspects of the Intricate Background of Immune-Related Cholangiopathies-A Critical Overview

Primary biliary cholangitis (PBC), and primary sclerosing cholangitis (PSC) are rare immune-related cholangiopathies with still poorly explained pathogenesis. Although triggers of chronic inflammation with subsequent fibrosis that affect cholangiocytes leading to obliteration of bile ducts and conversion to liver cirrhosis are unclear, both disorders are regarded to be multifactorial. Different factors can contribute to the development of hepatocellular injury in the course of progressive cholestasis, including (1) body accumulation of bile acids and their toxicity, (2) decreased food intake and nutrient absorption, (3) gut microbiota transformation, and (4) reorganized host metabolism. Growing evidence suggests that intestinal microbiome composition not only can be altered by liver dysfunction, but in turn, it actively impacts hepatic conditions. In this review, we highlight the role of key factors such as the gut-liver axis, intestinal barrier integrity, bile acid synthesis and circulation, and microbiome composition, which seem to be strongly related to PBC and PSC outcome. Emerging treatments and future therapeutic strategies are also presented.

Hepatoprotective Efficacy of Cycloastragenol Alleviated the Progression of Liver Fibrosis in Carbon-Tetrachloride-Treated Mice

The continuous death of hepatocytes induced by various etiologies leads to an aberrant tissue healing process and promotes the progression of liver fibrosis and ultimately chronic liver diseases. To date, effective treatments to delay this harmful process remain an unmet clinical need. Cycloastragenol is an active phytochemical substance isolated from Astragalus membranaceus, a plant used in traditional Chinese medicine to protect the liver. Therefore, our study aimed to elucidate the efficacy of cycloastragenol on carbon-tetrachloride (CCl₄)-induced liver fibrosis in mice. We found that cycloastragenol at 200 mg/kg dosage exhibited anti-fibrotic efficacy as demonstrated by a decrease in collagen deposition, downregulation of mRNA expression of collagen type 1, and a reduction in the content of total collagens. In addition, cycloastragenol further augmented the levels of anti-fibrotic matrix metalloproteinases (Mmps), that is, Mmp8, proMmp9, and Mmp12, which play a pivotal role in fibrosis resolution. According to histological analysis and serum markers of hepatotoxicity, cycloastragenol protected the livers from damage and mitigated the increment of serum alanine aminotransferase and bilirubin implicating hepatoprotective efficacy against CCl₄. Moreover, cycloastragenol upregulated the mRNA expression of interleukin 6, a pleiotropic cytokine plays a vital role in the promotion of hepatocyte regeneration. In conclusion, cycloastragenol alleviated the progression of liver fibrosis in CCl₄-treated mice and its anti-fibrotic efficacy was mainly due to the hepatoprotective efficacy.

Guidelines for the Management of Cholestatic Liver Diseases (2021)

In 2015, the Chinese Society of Hepatology and the Chinese Society of Gastroenterology issued a consensus statement on the diagnosis and management of cholestatic liver diseases. More clinical data on this topic have appeared during recent years. The Autoimmune Liver Disease Group of the Chinese Society of Hepatology organized an expert group to review recent evidence and provide an update to these previous guidelines. Herein, we provide 22 recommendations as a working reference for the management of cholestatic liver diseases by clinical practitioners.

Liver Ischemia and Reperfusion Induce Periportal Expression of Necroptosis Executor pMLKL Which Is Associated With Early Allograft Dysfunction After Transplantation

Background

Early allograft dysfunction (EAD) following liver transplantation (LT) remains a major threat to the survival of liver grafts and recipients. In animal models, it is shown that hepatic ischemia-reperfusion injury (IRI) triggers phosphorylation of Mixed Lineage Kinase domain-like protein (pMLKL) inducing necroptotic cell death. However, the clinical implication of pMLKL-mediated cell death in human hepatic IRI remains largely unexplored. In this study, we aimed to investigate the expression of pMLKL in human liver grafts and its association with EAD after LT.

Methods

The expression of pMLKL was determined by immunohistochemistry in liver biopsies obtained from both human and rat LT. Human liver biopsies were obtained at the end of preservation (T0) and ~1 hour after reperfusion (T1). The positivity of pMLKL was quantified electronically and compared in rat and human livers and post-LT outcomes. Multiplex immunofluorescence staining was performed to characterize the pMLKL-expressing cells.

Results

In the rat LT model, significant pMLKL expression was observed in livers after IRI as compared to livers of sham-operation animals. Similarly, the pMLKL score was highest after IRI in human liver grafts (in T1 biopsies). Both in rats and humans, the pMLKL expression is mostly observed in the portal triads. In grafts who developed EAD after LT (n=24), the pMLKL score at T1 was significantly higher as compared to non-EAD grafts (n=40). ROC curve revealed a high predictive value of pMLKL score at T1 (AUC 0.70) and the ratio of pMLKL score at T1 and T0 (pMLKL-index, AUC 0.82) for EAD. Liver grafts with a high pMLKL index (>1.64) had significantly higher levels of serum ALT, AST, and LDH 24 hours after LT compared to grafts with a low pMLKL index. Multivariate logistical regression analysis identified the pMLKL-index (Odds ratio=1.3, 95% CI 1.1-1.7) as a predictor of EAD development. Immunohistochemistry on serial sections and multiplex staining identified the periportal pMLKL-positive cells as portal fibroblasts, fibrocytes, and a minority of cholangiocytes.

Conclusion

Periportal pMLKL expression increased significantly after IRI in both rat and human LT. The histological score of pMLKL is predictive of post-transplant EAD and is associated with early liver injury after LT. Periportal non-parenchymal cells (i.e. fibroblasts) appear most susceptible to pMLKL-mediated cell death during hepatic IRI.

Circulating Extracellular Vesicles Contain Liver-Derived RNA Species as Indicators of Severe Cholestasis-Induced Early Liver Fibrosis in Mice

Aims: Biliary diseases represent around 10% of all chronic liver diseases and affect both adults and children. Currently available biochemical tests detect cholestasis but not early liver fibrosis. Circulating extracellular vesicles (EVs) provide a noninvasive, real-time molecular snapshot of the injured organ. We thus aimed at searching for a panel of EV-based biomarkers for cholestasis-induced early liver fibrosis using mouse models. Results: Progressive and detectable histological evidence of collagen deposition and liver fibrosis was observed from day 8 after bile duct ligation (BDL) in mice. Whole transcriptome and small RNA sequencing analyses of circulating EVs revealed differentially enriched RNA species after BDL versus sham controls. Unsupervised hierarchical clustering identified a signature that allowed for discrimination between BDL and controls. In particular, 151 microRNAs (miRNAs) enriched in BDL-derived EVs were identified, of which 66 were conserved in humans. The liver was an important source of circulating EVs in BDL animals as evidenced by the enrichment of several hepatic mRNAs, such as Albumin and Haptoglobin. Interestingly, among experimentally validated miRNAs, miR192-5p, miR194-5p, miR22-3p, and miR29a-3p showed similar enrichment patterns also in EVs derived from 3,5-diethoxycarboncyl-1,4-dihydrocollidine-treated (drug-induced severe cholestasis) but not in mice with mild phenotype or non-cholestatic liver fibrosis. Innovation: A panel of mRNAs and miRNAs contained in circulating EVs, when combined, indicates hepatic damage and fibrosis in mice and represents promising biomarkers for human severe cholestasis-induced liver fibrosis. Conclusion: Analysis of EV-based miRNAs, in combination with hepatic injury RNA markers, can detect early cholestatic liver injury and fibrosis in mice. Antioxid. Redox Signal. 36, 480-504.

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.

Hepatic stellate cells in the injured liver: Perspectives beyond hepatic fibrosis

Over the last two decades, our understanding of the pathological role of hepatic stellate cells (HSCs) in fibrotic liver disease has increased dramatically. As HSCs are identified as the principal collagen-producing cells in the injured liver, several experimental and clinical studies have targeted HSCs to treat liver fibrosis. However, HSCs also play a critical role in developing nonfibrotic liver diseases such as cholestasis, portal hypertension, and hepatocellular carcinoma (HCC). Therefore, this review exclusively focuses on the role of activated HSCs beyond hepatic fibrosis. In cholestasis conditions, elevated bile salts and bile acids activate HSCs to secrete collagen and other extracellular matrix products, which cause biliary fibrosis and cholangitis. In the chronically injured liver, autocrine and paracrine signaling from liver sinusoidal endothelial cells activates HSCs to induce portal hypertension via endothelin-1 release. In the tumor microenvironment (TME), activated HSCs are the major source of cancer-associated fibroblasts (CAF). The crosstalk between activated HSC/CAF and tumor cells is associated with tumor cell proliferation, migration, metastasis, and chemoresistance. In TME, activated HSCs convert macrophages to tumor-associated macrophages and induce the differentiation of dendritic cells (DCs) and monocytes to regulatory DCs and myeloid-derived suppressor cells, respectively. This differentiation, in turn, increases T cells proliferation and induces their apoptosis leading to reduced immune surveillance in TME. Thus, HSCs activation in chronically injured liver is a critical process involved in the progression of cholestasis, portal hypertension, and liver cancer.