Origin of myofibroblasts in the fibrotic liver in mice. Proc Natl Acad Sci U S A. 2014;111:E3297-E3305. [PMID: 25074909 DOI: 10.1073/pnas.1400062111]

Single-cell RNA sequencing reveals reduced intercellular adhesion molecule crosstalk between activated hepatic stellate cells and neutrophils alleviating liver fibrosis in hepatitis B virus transgenic mice post menstrual blood-derived mesenchymal stem cell transplantation

Liver fibrosis can cause hepatitis B virus (HBV)-associated hepatocellular carcinoma. Menstrual blood-derived mesenchymal stem cells (MenSCs) can ameliorate liver fibrosis through paracrine. Single-cell RNA sequencing (scRNA-seq) may be used to explore the roadmap of activated hepatic stellate cell (aHSC) inactivation to target liver fibrosis. This study established HBV transgenic (HBV-Tg) mouse model of carbon tetrachloride (CCl4)-induced liver fibrosis and demonstrated that MenSCs migrated to the injured liver to improve serological indices and reduce fibrotic accumulation. RNA-bulk analysis revealed that MenSCs mediated extracellular matrix accumulation and cell adhesion. Liver parenchymal cells and nonparenchymal cells were identified by scRNA-seq in the control, CCl4, and MenSC groups, revealing the heterogeneity of fibroblasts/HSCs. A CellChat analysis revealed that diminished intercellular adhesion molecule (ICAM) signaling is vital for MenSC therapy. Specifically, Icam1 in aHSCs acted on Itgal/Itgb2 and Itgam/Itgb2 in neutrophils, causing decreased adhesion. The expression of Itgal, Itgam, and Itgb2 was higher in CCl4 group than in the control group and decreased after MenSC therapy in neutrophil clusters. The Lcn2, Pglyrp1, Wfdc21, and Mmp8 had high expression and may be potential targets in neutrophils. This study highlights interacting cells, corresponding molecules, and underlying targets for MenSCs in treating HBV-associated liver fibrosis.

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.

Deletion of GPR81 activates CREB/Smad7 pathway and alleviates liver fibrosis in mice

BACKGROUND

Enhanced glycolysis is a crucial metabolic event that drives the development of liver fibrosis, but the molecular mechanisms have not been fully understood. Lactate is the endproduct of glycolysis, which has recently been identified as a bioactive metabolite binding to G-protein-coupled receptor 81 (GPR81). We then questioned whether GPR81 is implicated in the development of liver fibrosis.

METHODS

The level of GPR81 was determined in mice with carbon tetrachloride (CCl4)-induced liver fibrosis and in transforming growth factor beta 1 (TGF-β1)-activated hepatic stellate cells (HSCs) LX-2. To investigate the significance of GPR81 in liver fibrosis, wild-type (WT) and GPR81 knockout (KO) mice were exposed to CCl4, and then the degree of liver fibrosis was determined. In addition, the GPR81 agonist 3,5-dihydroxybenzoic acid (DHBA) was supplemented in CCl4-challenged mice and TGF-β1-activated LX-2 cells to further investigate the pathological roles of GPR81 on HSCs activation.

RESULTS

CCl4 exposure or TGF-β1 stimulation significantly upregulated the expression of GPR81, while deletion of GPR81 alleviated CCl4-induced elevation of aminotransferase, production of pro-inflammatory cytokines, and deposition of collagen. Consistently, the production of TGF-β1, the expression of alpha-smooth muscle actin (α-SMA) and collagen I (COL1A1), as well as the elevation of hydroxyproline were suppressed in GPR81 deficient mice. Supplementation with DHBA enhanced CCl4-induced liver fibrogenesis in WT mice but not in GPR81 KO mice. DHBA also promoted TGF-β1-induced LX-2 activation. Mechanistically, GPR81 suppressed cAMP/CREB and then inhibited the expression of Smad7, a negative regulator of Smad3, which resulted in increased phosphorylation of Smad3 and enhanced activation of HSCs.

CONCLUSION

GPR81 might be a detrimental factor that promotes the development of liver fibrosis by regulating CREB/Smad7 pathway.

Endothelial POFUT1 controls injury-induced liver fibrosis by repressing fibrinogen synthesis

BACKGROUND & AIMS

NOTCH signaling in liver sinusoidal endothelial cells (LSECs) regulates liver fibrosis, a pathological feature of chronic liver diseases. POFUT1 is an essential regulator of NOTCH signaling. Here, we investigated the role of LSEC-expressed POFUT1 in liver fibrosis.

METHODS

Endothelial-specific Pofut1 knockout mice were generated and experimental liver fibrosis was induced by chronic carbon tetrachloride exposure or common bile duct ligation. Liver samples were assessed by ELISA, histology, electron microscopy, immunostaining and RNA in situ hybridization. LSECs and hepatic stellate cells (HSCs) were isolated for gene expression analysis by RNA sequencing, qPCR, and western blotting. Signaling crosstalk between LSECs and HSCs was investigated by treating HSCs with supernatant from LSEC cultures. Liver single-cell RNA sequencing datasets from patients with cirrhosis and healthy individuals were analyzed to evaluate the clinical relevance of gene expression changes observed in mouse studies.

RESULTS

POFUT1 loss promoted injury-induced LSEC capillarization and HSC activation, leading to aggravated liver fibrosis. RNA sequencing analysis revealed that POFUT1 deficiency upregulated fibrinogen expression in LSECs. Consistently, fibrinogen was elevated in LSECs of patients with cirrhosis. HSCs treated with supernatant from LSECs of Pofut1 null mice showed exacerbated activation compared to those treated with supernatant from control LSECs, and this effect was attenuated by knockdown of fibrinogen or by pharmacological inhibition of fibrinogen receptor signaling, altogether suggesting that LSEC-derived fibrinogen induced the activation of HSCs. Mechanistically, POFUT1 loss augmented fibrinogen expression by enhancing NOTCH/HES1/STAT3 signaling.

CONCLUSIONS

Endothelial POFUT1 prevents injury-induced liver fibrosis by repressing the expression of fibrinogen, which functions as a profibrotic paracrine signal to activate HSCs. Therapies targeting the POFUT1/fibrinogen axis offer a promising strategy for the prevention and treatment of fibrotic liver diseases.

IMPACT AND IMPLICATIONS

Paracrine signals produced by liver vasculature play a major role in the development of liver fibrosis, which is a pathological hallmark of most liver diseases. Identifying those paracrine signals is clinically relevant in that they may serve as therapeutic targets. In this study, we discovered that genetic deletion of Pofut1 aggravated experimental liver fibrosis in mouse models. Moreover, fibrinogen was identified as a downstream target repressed by Pofut1 in liver endothelial cells and functioned as a novel paracrine signal that drove liver fibrosis. In addition, fibrinogen was found to be relevant to cirrhosis and may serve as a potential therapeutic target for this devastating human disease.

Smart Microneedle Arrays Integrating Cell-Free Therapy and Nanocatalysis to Treat Liver Fibrosis

Liver fibrosis is a chronic pathological condition lacking specific clinical treatments. Stem cells, with notable potential in regenerative medicine, offer promise in treating liver fibrosis. However, stem cell therapy is hindered by potential immunological rejection, carcinogenesis risk, efficacy variation, and high cost. Stem cell secretome-based cell-free therapy offers potential solutions to address these challenges, but it is limited by low delivery efficiency and rapid clearance. Herein, an innovative approach for in situ implantation of smart microneedle (MN) arrays enabling precisely controlled delivery of multiple therapeutic agents directly into fibrotic liver tissues is developed. By integrating cell-free and platinum-based nanocatalytic combination therapy, the MN arrays can deactivate hepatic stellate cells. Moreover, they promote excessive extracellular matrix degradation by more than 75%, approaching normal levels. Additionally, the smart MN arrays can provide hepatocyte protection while reducing inflammation levels by ≈70-90%. They can also exhibit remarkable capability in scavenging almost 100% of reactive oxygen species and alleviating hypoxia. Ultimately, this treatment strategy can effectively restrain fibrosis progression. The comprehensive in vitro and in vivo experiments, supplemented by proteome and transcriptome analyses, substantiate the effectiveness of the approach in treating liver fibrosis, holding immense promise for clinical applications.

Delivery technologies for therapeutic targeting of fibronectin in autoimmunity and fibrosis applications

Fibronectin (FN) is a critical component of the extracellular matrix (ECM) contributing to various physiological processes, including tissue repair and immune response regulation. FN regulates various cellular functions such as adhesion, proliferation, migration, differentiation, and cytokine release. Alterations in FN expression, deposition, and molecular structure can profoundly impact its interaction with other ECM proteins, growth factors, cells, and associated signaling pathways, thus influencing the progress of diseases such as fibrosis and autoimmune disorders. Therefore, developing therapeutics that directly target FN or its interaction with cells and other ECM components can be an intriguing approach to address autoimmune and fibrosis pathogenesis.

Interplay between YAP/TAZ and metabolic dysfunction-associated steatotic liver disease progression

Metabolic dysfunction-associated steatotic liver disease (MASLD) is becoming an increasingly pressing global health challenge, with increasing mortality rates showing an upward trend. Two million deaths occur annually from cirrhosis and liver cancer together each year. Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ), key effectors of the Hippo signaling pathway, critically regulate tissue homeostasis and disease progression in the liver. While initial studies have shown that YAP expression is normally restricted to cholangiocytes in healthy livers, the activation of YAP/TAZ is observed in other hepatic cells during chronic liver disease. The disease-driven dysregulation of YAP/TAZ appears to be a critical element in the MASLD progression, contributing to hepatocyte dysfunction, inflammation, and fibrosis. In this study, we focused on the complex roles of YAP/TAZ in MASLD and explored how the YAP/TAZ dysregulation of YAP/TAZ drives steatosis, inflammation, fibrosis, and cirrhosis. Finally, the cell-type-specific functions of YAP/TAZ in different types of hepatic cells, such as hepatocytes, hepatic stellate cells, hepatic macrophages, and biliary epithelial cells are discussed, highlighting the multifaceted impact of YAP/TAZ on liver physiology and pathology.

The antiprotozoal drug nitazoxanide improves experimental liver fibrosis in mice

Nitazoxanide is an FDA-approved antiprotozoal drug. Our previous studies find that nitazoxanide and its metabolite tizoxanide affect AMPK, STAT3, and Smad2/3 signals which are involved in the pathogenesis of liver fibrosis, therefore, in the present study, we examined the effect of nitazoxanide on experimental liver fibrosis and elucidated the potential mechanisms. The in vivo experiment results showed that oral nitazoxanide (75, 100 mg·kg-1) significantly improved CCl4- and bile duct ligation-induced liver fibrosis in mice. Oral nitazoxanide activated the inhibited AMPK and inhibited the activated STAT3 in liver tissues from liver fibrosis mice. The in vitro experiment results showed that nitazoxanide and its metabolite tizoxanide activated AMPK and inhibited STAT3 signals in LX-2 cells (human hepatic stellate cells). Nitazoxanide and tizoxanide inhibited cell proliferation and collagen I expression and secretion of LX-2 cells. Nitazoxanide and tizoxanide inhibited transforming growth factor-β1 (TGF-β1)- and IL-6-induced increases of cell proliferation, collagen I expression and secretion, inhibited TGF-β1- and IL-6-induced STAT3 and Smad2/3 activation in LX-2 cells. In mouse primary hepatic stellate cells, nitazoxanide and tizoxanide also activated AMPK, inhibited STAT3 and Smad2/3 activation, inhibited cell proliferation, collagen I expression and secretion. In conclusion, nitazoxanide inhibits liver fibrosis and the underlying mechanisms involve AMPK activation, and STAT3 and Smad2/3 inhibition.

Tissue fibroblasts are versatile immune regulators: An evaluation of their impact on the aging process

Fibroblasts are abundant stromal cells which not only control the integrity of extracellular matrix (ECM) but also act as immune regulators. It is known that the structural cells within tissues can establish an organ-specific immunity expressing many immune-related genes and closely interact with immune cells. In fact, fibroblasts can modify their immune properties to display both pro-inflammatory and immunosuppressive activities in a context-dependent manner. After acute insults, fibroblasts promote tissue inflammation although they concurrently recruit immunosuppressive cells to enhance the resolution of inflammation. In chronic pathological states, tissue fibroblasts, especially senescent fibroblasts, can display many pro-inflammatory and immunosuppressive properties and stimulate the activities of different immunosuppressive cells. In return, immunosuppressive cells, such as M2 macrophages and myeloid-derived suppressor cells (MDSC), evoke an excessive conversion of fibroblasts into myofibroblasts, thus aggravating the severity of tissue fibrosis. Single-cell transcriptome studies on fibroblasts isolated from aged tissues have confirmed that tissue fibroblasts express many genes coding for cytokines, chemokines, and complement factors, whereas they lose some fibrogenic properties. The versatile immune properties of fibroblasts and their close cooperation with immune cells indicate that tissue fibroblasts have a crucial role in the aging process and age-related diseases.

A short-term rodent model for non-alcoholic steatohepatitis induced by a high-fat diet and carbon tetrachloride

Several models of mice-fed high-fat diets have been used to trigger non-alcoholic steatohepatitis and some chemical substances, such as carbon tetrachloride. The present study aimed to evaluate the joint action of a high-fat diet and CCl4 in developing a short-term non-alcoholic steatohepatitis model. C57BL6/J mice were divided into two groups: standard diet-fed (SD), the high-fat diet-fed (HFD) and HFD + fructose-fed and carbon tetrachloride (HFD+CCl4). The animals fed with HFD+CCl4 presented increased lipid deposition compared with both SD and HFD mice. Plasma cholesterol was increased in animals from the HFD+CCl4 group compared with the SD and HFD groups, without significant differences between the SD and HFD groups. Plasma triglycerides showed no significant difference between the groups. The HFD+CCl4 animals had increased collagen deposition in the liver compared with both SD and HFD groups. Hydroxyproline was also increased in the HFD+CCl4 group. Liver enzymes, alanine aminotransferase and aspartate aminotransferase, were increased in the HFD+CCl4 group, compared with SD and HFD groups. Also, CCl4 was able to trigger an inflammatory process in the liver of HFD-fed animals by promoting an increase of ∼2 times in macrophage activity, ∼6 times in F4/80 gene expression, and pro-inflammatory cytokines (IL-1b and TNFa), in addition to an increase in inflammatory pathway protein phosphorylation (IKKbp). HFD e HFD+CCl4 animals increased glucose intolerance compared with SD mice, associated with reduced insulin-stimulated AKT activity in the liver. Therefore, our study has shown that short-term HFD feeding associated with fructose and CCl4 can trigger non-alcoholic steatohepatitis and cause damage to glucose metabolism.

Orphan receptor GPR176 in hepatic stellate cells exerts a profibrotic role in chronic liver disease

Background & Aims

Chronic liver disease (CLD) remains a global health issue associated with a significant disease burden. Liver fibrosis, a hallmark of CLD, is characterised by the activation of hepatic stellate cells (HSCs) that gain profibrotic characteristics including increased production of extracellular matrix protein. Currently, no antifibrotic therapies are available clinically, in part because of the lack of HSC-specific drug targets. Here, we aimed to identify HSC-specific membrane proteins that can serve as targets for antifibrotic drug development.

Methods

Small interfering RNA-mediated knockdown of GPR176 was used to assess the in vitro function of GPR176 in HSCs and in precision cut liver slices (PCLS). The in vivo role of GPR176 was assessed using the carbon tetrachloride (CCl4) and common bile duct ligation (BDL) models in wild-type and GPR176 knockout mice. GPR176 in human CLD was assessed by immunohistochemistry of diseased human livers and RNA expression analysis in human primary HSCs and transcriptomic data sets.

Results

We identified Gpr176, an orphan G-protein coupled receptor, as an HSC-enriched activation associated gene. In vitro, Gpr176 is strongly induced upon culture-induced and hepatocyte-damage-induced activation of primary HSCs. Knockdown of GPR176 in primary mouse HSCs or PCLS cultures resulted in reduced fibrogenic characteristics. Absence of GPR176 did not influence liver homeostasis, but Gpr176-/- mice developed less severe fibrosis in CCl4 and BDL fibrosis models. In humans, GPR176 expression was correlated with in vitro HSC activation and with fibrosis stage in patients with CLD.

Conclusions

GPR176 is a functional protein during liver fibrosis and reducing its activity attenuates fibrogenesis. These results highlight the potential of GPR176 as an HSC-specific antifibrotic candidate to treat CLD.

Impact and implications

The lack of effective antifibrotic drugs is partly attributed to the insufficient knowledge about the mechanisms involved in the development of liver fibrosis. We demonstrate that the G-protein coupled receptor GPR176 contributes to fibrosis development. Since GPR176 is specifically expressed on the membrane of activated hepatic stellate cells and is linked with fibrosis progression in humans, it opens new avenues for the development of targeted interventions.

Heterogeneity of primary and metastatic CAFs: From differential treatment outcomes to treatment opportunities (Review)

Compared with primary tumor sites, metastatic sites appear more resistant to treatments and respond differently to the treatment regimen. It may be due to the heterogeneity in the microenvironment between metastatic sites and primary tumors. Cancer‑associated fibroblasts (CAFs) are widely present in the tumor stroma as key components of the tumor microenvironment. Primary tumor CAFs (pCAFs) and metastatic CAFs (mCAFs) are heterogeneous in terms of source, activation mode, markers and functional phenotypes. They can shape the tumor microenvironment according to organ, showing heterogeneity between primary tumors and metastases, which may affect the sensitivity of these sites to treatment. It was hypothesized that understanding the heterogeneity between pCAFs and mCAFs can provide a glimpse into the difference in treatment outcomes, providing new ideas for improving the rate of metastasis control in various cancers.

Fibrosis in IBD: from pathogenesis to therapeutic targets

BACKGROUND

Intestinal fibrosis resulting in stricture formation and obstruction in Crohn's disease (CD) and increased wall stiffness leading to symptoms in ulcerative colitis (UC) is among the largest unmet needs in inflammatory bowel disease (IBD). Fibrosis is caused by a multifactorial and complex process involving immune and non-immune cells, their soluble mediators and exposure to luminal contents, such as microbiota and environmental factors. To date, no antifibrotic therapy is available. Some progress has been made in creating consensus definitions and measurements to quantify stricture morphology for clinical practice and trials, but approaches to determine the degree of fibrosis within a stricture are still lacking.

OBJECTIVE

We herein describe the current state of stricture pathogenesis, measuring tools and clinical trial endpoints development.

DESIGN

Data presented and discussed in this review derive from the past and recent literature and the authors' own research and experience.

RESULTS AND CONCLUSIONS

Significant progress has been made in better understanding the pathogenesis of fibrosis, but additional studies and preclinical developments are needed to define specific therapeutic targets.

[18F]AlF-ND-bisFAPI PET imaging of fibroblast activation protein as a biomarker to monitor the progression of liver fibrosis

BACKGROUND

Hepatic fibrosis is a progressive disease, which is reversible in the early stages. The current monitoring methods have notable limitations that pose a challenge to early detection. In this study, we evaluated the utility of [18F]AlF-ND-bisFAPI positron emission tomography imaging of fibroblast activation protein (FAP) to monitor the progression of liver fibrosis.

METHODS

Two mouse models of liver fibrosis were established by bile duct ligation and carbon tetrachloride administration, respectively. Positron emission tomography imaging was performed with the FAP-specific radiotracer [18F]AlF-ND-bisFAPI for the evaluation of rat HSCs and mouse models of fibrosis and combined with histopathology, immunohistochemical staining, and immunoblotting to elucidate the relationships among radioactivity uptake, FAP levels, and liver fibrosis progression. Furthermore, [18F]AlF-ND-bisFAPI autoradiography was performed to assess tracer binding in liver sections from patients with varying degrees of liver fibrosis.

RESULTS

Cell experiments demonstrated that [18F]AlF-ND-bisFAPI uptake was specific in activated HSCs. Compared with control mice, [18F]AlF-ND-bisFAPI uptake in livers increased in the early stages of fibrosis and increased significantly further with disease progression. Immunohistochemistry and western blot analyses demonstrated that FAP expression increased with fibrosis severity. In accordance with the findings in animal models, ex vivo autoradiography on human fibrotic liver sections showed that radioactivity increased as fibrosis progressed from mild to severe.

CONCLUSIONS

[18F]AlF-ND-bisFAPI positron emission tomography imaging is a promising noninvasive method for monitoring the progression of liver fibrosis.

Research reviews and prospects of gut microbiota in liver cirrhosis: a bibliometric analysis (2001-2023)

INTRODUCTION

The gut-liver axis has emerged as a focal point in chronic liver disorders, prompting more research into the role of the gut microbiota in liver cirrhosis. In individuals with liver cirrhosis, changes in the structure and function of the gut microbiota are closely tied to clinical prognosis. However, there is a scarcity of bibliometric evaluations conducted in this particular field.

METHODS

This study is aiming to conduct a complete analysis of the knowledge structure and centers pertaining to gut microbiota in liver cirrhosis using bibliometric methods. Publications on gut microbiota and liver cirrhosis from 2001 to 2023 are sourced from the Web of Science Core Collection. For the bibliometric analysis, we employ VOSviewer, CiteSpace, and the R package "bibliometrix".

RESULTS

Our study encompasses a comprehensive collection of 3109 articles originating from 96 countries, with notable contributions from leading nations such as the United States and China. The quantity of publications concerning the gut microbiota of liver cirrhosis rises annually. The University of California San Diego, Virginia Commonwealth University, Zhejiang University are the primary research institutions. World Journal of Gastroenterology publishes the most papers in this field, while hepatology is the most frequently co-cited journal. These publications come from a total of 15,965 authors, and the most prolific authors are Bajaj Jasmohan S., Schnabl Bernd and Gillevet Patrick M., while the most co-cited authors are Bajaj Jasmohan S., Younossi Zobair M., and Reiner Wiest. In addition, "dysbiosis", "gut microbiota", "intestinal barrier", "fecal microbiota transplantation", and "complement-system" are the primary keywords of research trends in recent years.

DISCUSSION

This study offering a comprehensive insight into the research dynamics surrounding gut microbiota in patients with liver cirrhosis. It delineates the current research frontiers and hotspots, serving as a valuable guide for scholars.

Liver fibrosis pathologies and potentials of RNA based therapeutics modalities

Liver fibrosis (LF) occurs when the liver tissue responds to injury or inflammation by producing excessive amounts of scar tissue, known as the extracellular matrix. This buildup stiffens the liver tissue, hinders blood flow, and ultimately impairs liver function. Various factors can trigger this process, including bloodborne pathogens, genetic predisposition, alcohol abuse, non-steroidal anti-inflammatory drugs, non-alcoholic steatohepatitis, and non-alcoholic fatty liver disease. While some existing small-molecule therapies offer limited benefits, there is a pressing need for more effective treatments that can truly cure LF. RNA therapeutics have emerged as a promising approach, as they can potentially downregulate cytokine levels in cells responsible for liver fibrosis. Researchers are actively exploring various RNA-based therapeutics, such as mRNA, siRNA, miRNA, lncRNA, and oligonucleotides, to assess their efficacy in animal models. Furthermore, targeted drug delivery systems hold immense potential in this field. By utilizing lipid nanoparticles, exosomes, nanocomplexes, micelles, and polymeric nanoparticles, researchers aim to deliver therapeutic agents directly to specific biomarkers or cytokines within the fibrotic liver, increasing their effectiveness and reducing side effects. In conclusion, this review highlights the complex nature of liver fibrosis, its underlying causes, and the promising potential of RNA-based therapeutics and targeted delivery systems. Continued research in these areas could lead to the development of more effective and personalized treatment options for LF patients.

Water extract of earthworms mitigates mouse liver fibrosis by potentiating hepatic LKB1/Nrf2 axis to inhibit HSC activation and hepatocyte death

ETHNOPHARMACOLOGICAL RELEVANCE

When left untreated, liver fibrosis (LF) causes various chronic liver diseases. Earthworms (Pheretima aspergillum) are widely used in traditional medicine because of their capacity to relieve hepatic diseases.

AIM OF THE STUDY

This study aimed to explore the anti-LF effects of water extract of earthworms (WEE) and the underlying molecular mechanisms.

MATERIALS AND METHODS

A CCl4-induced mouse model of LF was used to study the impact of WEE on LF in vivo. The anti-LF activity of WEE in mice was compared with that of silybin, which can be clinically applied in LF intervention and was used as a positive control. Activation of LX-2 hepatic stellate cells (HSCs) and apoptosis and ferroptosis of AML-12 hepatocytes induced by TGFβ1 were used as in vitro models.

RESULTS

WEE drastically improved LF in mice. WEE reduced markers of activated HSCs in mice and inhibited TGFβ1-induced activation of LX-2 HSCs in vitro. Additionally, WEE suppressed CCl4-induced apoptosis and ferroptosis in mouse hepatocytes. Mechanistically, WEE induced Nrf2 to enter the nuclei of the mouse liver cells, and the hepatic levels of Nrf2-downstream antioxidative factors increased. LKB1/AMPK/GSK3β is an upstream regulatory cascade of Nrf2. In the LF mouse model, WEE increased hepatic phosphorylated LKB1, AMPK, and GSK3β levels. Similar results were obtained for the LX-2 cells. In AML-12 hepatocytes and LX-2 HSCs, WEE elevated intracellular Nrf2 levels, promoted its nuclear translocation, and inhibited TGFβ1-induced ROS accumulation. Knocking down LKB1 abolished the impact of WEE on the AMPK/GSK3β/Nrf2 cascade and eliminated its protective effects against TGFβ1.

CONCLUSIONS

Our findings reveal that WEE improves mouse LF triggered by CCl4 and supports its application as a promising hepatoprotective agent against LF. The potentiation of the hepatic antioxidative AMPK/GSK3β/Nrf2 cascade by activating LKB1 and the subsequent suppression of HSC activation and hepatocyte apoptosis and ferroptosis are implicated in WEE-mediated alleviation of LF.

Ginkgetin exhibits antifibrotic effects by inducing hepatic stellate cell apoptosis via STAT1 activation

Liver fibrosis affects approximately 800 million patients worldwide, with over 2 million deaths each year. Nevertheless, there are no approved medications for treating liver fibrosis. In this study, we investigated the impacts of ginkgetin on liver fibrosis and the underlying mechanisms. The impacts of ginkgetin on liver fibrosis were assessed in mouse models induced by thioacetamide or bile duct ligation. Experiments on human LX-2 cells and primary mouse hepatic stellate cells (HSCs) were performed to explore the underlying mechanisms, which were also validated in the mouse models. Ginkgetin significantly decreased hepatic extracellular matrix deposition and HSC activation in the fibrotic models induced by thioacetamide (TAA) and bile duct ligation (BDL). Beneficial effects also existed in inhibiting hepatic inflammation and improving liver function. In vitro experiments showed that ginkgetin markedly inhibited HSC viability and induced HSC apoptosis dose-dependently. Mechanistic studies revealed that the antifibrotic effects of ginkgetin depend on STAT1 activation, as the effects were abolished in vitro after STAT1 silencing and in vivo after inhibiting STAT1 activation by fludarabine. Moreover, we observed a meaningful cross-talk between HSCs and hepatocytes, in which IL-6, released by ginkgetin-induced apoptotic HSCs, enhanced hepatocyte proliferation by activating STAT3 signaling. Ginkgetin exhibits antifibrotic effects by inducing HSC apoptosis via STAT1 activation and enhances hepatocyte proliferation secondary to HSC apoptosis via the IL-6/STAT3 pathway.

Role of Hippo pathway dysregulation from gastrointestinal premalignant lesions to cancer

BACKGROUND

First identified in Drosophila melanogaster, the Hippo pathway is considered a major regulatory cascade controlling tissue homeostasis and organ development. Hippo signaling components include kinases whose activity regulates YAP and TAZ final effectors. In response to upstream stimuli, YAP and TAZ control transcriptional programs involved in cell proliferation, cytoskeletal reorganization and stemness.

MAIN TEXT

While fine tuning of Hippo cascade components is essential for maintaining the balance between proliferative and non-proliferative signals, pathway signaling is frequently dysregulated in gastrointestinal cancers. Also, YAP/TAZ aberrant activation has been described in conditions characterized by chronic inflammation that precede cancer development, suggesting a role of Hippo effectors in triggering carcinogenesis. In this review, we summarize the architecture of the Hippo pathway and discuss the involvement of signaling cascade unbalances in premalignant lesions of the gastrointestinal tract, providing a focus on the underlying molecular mechanisms.

CONCLUSIONS

The biology of premalignant Hippo signaling dysregulation needs further investigation in order to elucidate the evolutionary trajectories triggering cancer inititation and develop effective early therapeutic strategies targeting the Hippo/YAP pathway.

Epigenetic Regulation of EMP/EMT-Dependent Fibrosis

Fibrosis represents a process characterized by excessive deposition of extracellular matrix (ECM) proteins. It often represents the evolution of pathological conditions, causes organ failure, and can, in extreme cases, compromise the functionality of organs to the point of causing death. In recent years, considerable efforts have been made to understand the molecular mechanisms underlying fibrotic evolution and to identify possible therapeutic strategies. Great interest has been aroused by the discovery of a molecular association between epithelial to mesenchymal plasticity (EMP), in particular epithelial to mesenchymal transition (EMT), and fibrogenesis, which has led to the identification of complex molecular mechanisms closely interconnected with each other, which could explain EMT-dependent fibrosis. However, the result remains unsatisfactory from a therapeutic point of view. In recent years, advances in epigenetics, based on chromatin remodeling through various histone modifications or through the intervention of non-coding RNAs (ncRNAs), have provided more information on the fibrotic process, and this could represent a promising path forward for the identification of innovative therapeutic strategies for organ fibrosis. In this review, we summarize current research on epigenetic mechanisms involved in organ fibrosis, with a focus on epigenetic regulation of EMP/EMT-dependent fibrosis.

Osr1-mediated mesothelial transition of liver mesenchymal cells exacerbates fibrotic liver damage

In chronic liver diseases, hepatic stellate cells (HSCs) are induced to form the myofibroblasts responsible for scar formation, leading to liver fibrosis and cirrhosis. Here, single-cell RNA sequencing with in vivo lineage tracing in nonalcoholic steatohepatitis (NASH) model mice reveals a subpopulation of HSCs transitioning back to a state resembling their developmental precursors, mesothelial cells (MCs), after liver injury. These damage-associated intermediates between HSCs and MCs (DIHMs) can be traced with a dual recombinase system by labeling Krt19-expressing cells within prelabeled Pdgfrb+ HSCs, and DIHMs highly express inflammation- and fibrosis-associated genes. Cre and Dre-inducible depletion of DIHMs by administering diphtheria toxin reduces liver fibrosis and alleviates liver damage in NASH model mice. Importantly, knockdown of Osr1, a zinc finger transcription factor of the OSR gene family, can block DIHM induction in vitro. Conditional knockout Osr1 in Pdgfrb-expressing mesenchymal cells in NASH model mice can reduce liver fibrosis in vivo. Our study collectively uncovers an injury-induced developmental reversion process wherein HSCs undergo what we call a mesenchymal-to-mesothelial transition, which can be targeted to develop interventions to treat chronic liver diseases.

Amphiregulin from regulatory T cells promotes liver fibrosis and insulin resistance in non-alcoholic steatohepatitis

Production of amphiregulin (Areg) by regulatory T (Treg) cells promotes repair after acute tissue injury. Here, we examined the function of Treg cells in non-alcoholic steatohepatitis (NASH), a setting of chronic liver injury. Areg-producing Treg cells were enriched in the livers of mice and humans with NASH. Deletion of Areg in Treg cells, but not in myeloid cells, reduced NASH-induced liver fibrosis. Chronic liver damage induced transcriptional changes associated with Treg cell activation. Mechanistically, Treg cell-derived Areg activated pro-fibrotic transcriptional programs in hepatic stellate cells via epidermal growth factor receptor (EGFR) signaling. Deletion of Areg in Treg cells protected mice from NASH-dependent glucose intolerance, which also was dependent on EGFR signaling on hepatic stellate cells. Areg from Treg cells promoted hepatocyte gluconeogenesis through hepatocyte detection of hepatic stellate cell-derived interleukin-6. Our findings reveal a maladaptive role for Treg cell-mediated tissue repair functions in chronic liver disease and link liver damage to NASH-dependent glucose intolerance.

Organelle stress and alterations in interorganelle crosstalk during liver fibrosis

The synchronous functioning and quality control of organelles ensure cell survival and function and are essential for maintaining homeostasis. Prolonged exposure to stressors (viruses, bacteria, parasitic infections, alcohol, drugs) or genetic mutations often disrupt the functional integrity of organelles which plays a critical role in the initiation and progression of several diseases including chronic liver diseases. One of the most important pathologic consequences of chronic liver diseases is liver fibrosis, characterized by tissue scarring due to the progressive accumulation of extracellular matrix components. Left untreated, fibrosis may advance to life-threatening complications such as cirrhosis, hepatic decompensation, and HCC, which collectively accounts for ∼1 million deaths per year worldwide. Owing to the lack of treatment options that can regress or reverse cirrhosis, liver transplantation is currently the only available treatment for end-stage liver disease. However, the limited supply of usable donor organs, adverse effects of lifelong immunosuppressive regimes, and financial considerations pose major challenges and limit its application. Hence, effective therapeutic strategies are urgently needed. An improved understanding of the organelle-level regulation of fibrosis can help devise effective antifibrotic therapies focused on reducing organelle stress, limiting organelle damage, improving interorganelle crosstalk, and restoring organelle homeostasis; and could be a potential clinical option to avoid transplantation. This review provides a timely update on the recent findings and mechanisms covering organelle-specific dysfunctions in liver fibrosis, highlights how correction of organelle functions opens new treatment avenues and discusses the potential challenges to clinical application.

MSC-derived exosomes attenuate hepatic fibrosis in primary sclerosing cholangitis through inhibition of Th17 differentiation

Primary sclerosing cholangitis (PSC) is an autoimmune cholangiopathy characterized by chronic inflammation of the biliary epithelium and periductal fibrosis, with no curative treatment available, and liver transplantation is inevitable for end-stage patients. Human placental mesenchymal stem cell (hpMSC)-derived exosomes have demonstrated the ability to prevent fibrosis, inhibit collagen production and possess immunomodulatory properties in autoimmune liver disease. Here, we prepared hpMSC-derived exosomes (ExoMSC) and further investigated the anti-fibrotic effects and detailed mechanism on PSC based on Mdr2-/- mice and multicellular organoids established from PSC patients. The results showed that ExoMSC ameliorated liver fibrosis in Mdr2-/- mice with significant collagen reduction in the preductal area where Th17 differentiation was inhibited as demonstrated by RNAseq analysis, and the percentage of CD4+IL-17A+T cells was reduced both in ExoMSC-treated Mdr2-/- mice (Mdr2-/--Exo) in vivo and ExoMSC-treated Th17 differentiation progressed in vitro. Furthermore, ExoMSC improved the hypersecretory phenotype and intercellular interactions in the hepatic Th17 microenvironment by regulating PERK/CHOP signaling as supported by multicellular organoids. Thus, our data demonstrate the anti-fibrosis effect of ExoMSC in PSC disease by inhibiting Th17 differentiation, and ameliorating the Th17-induced microenvironment, indicating the promising potential therapeutic role of ExoMSC in liver fibrosis of PSC or Th17-related diseases.

Cellular Interactions and Crosstalk Facilitating Biliary Fibrosis in Cholestasis

Biliary fibrosis is seen in cholangiopathies, including primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC). In PBC and PSC, biliary fibrosis is associated with worse outcomes and histologic scores. Within the liver, both hepatic stellate cells (HSCs) and portal fibroblasts (PFs) contribute to biliary fibrosis, but their roles can differ. PFs reside near the bile ducts and may be the first responders to biliary damage, whereas HSCs may be recruited later and initiate bridging fibrosis. Indeed, different models of biliary fibrosis can activate PFs and HSCs to varying degrees. The portal niche can be composed of cholangiocytes, HSCs, PFs, endothelial cells, and various immune cells, and interactions between these cell types drive biliary fibrosis. In this review, we discuss the mechanisms of biliary fibrosis and the roles of PFs and HSCs in this process. We will also evaluate cellular interactions and mechanisms that contribute to biliary fibrosis in different models and highlight future perspectives and potential therapeutics.

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.

Redox Biology and Liver Fibrosis

Hepatic fibrosis is a complex process that develops in chronic liver diseases. Even though the initiation and progression of fibrosis rely on the underlying etiology, mutual mechanisms can be recognized and targeted for therapeutic purposes. Irrespective of the primary cause of liver disease, persistent damage to parenchymal cells triggers the overproduction of reactive species, with the consequent disruption of redox balance. Reactive species are important mediators for the homeostasis of both hepatocytes and non-parenchymal liver cells. Indeed, other than acting as cytotoxic agents, reactive species are able to modulate specific signaling pathways that may be relevant to hepatic fibrogenesis. After a brief introduction to redox biology and the mechanisms of fibrogenesis, this review aims to summarize the current evidence of the involvement of redox-dependent pathways in liver fibrosis and focuses on possible therapeutic targets.

Macrophages and platelets in liver fibrosis and hepatocellular carcinoma

During fibrosis, (myo)fibroblasts deposit large amounts of extracellular matrix proteins, thereby replacing healthy functional tissue. In liver fibrosis, this leads to the loss of hepatocyte function, portal hypertension, variceal bleeding, and increased susceptibility to infection. At an early stage, liver fibrosis is a dynamic and reversible process, however, from the cirrhotic stage, there is significant progression to hepatocellular carcinoma. Both liver-resident macrophages (Kupffer cells) and monocyte-derived macrophages are important drivers of fibrosis progression, but can also induce its regression once triggers of chronic inflammation are eliminated. In liver cancer, they are attracted to the tumor site to become tumor-associated macrophages (TAMs) polarized towards a M2- anti-inflammatory/tumor-promoting phenotype. Besides their role in thrombosis and hemostasis, platelets can also stimulate fibrosis and tumor development by secreting profibrogenic factors and regulating the innate immune response, e.g., by interacting with monocytes and macrophages. Here, we review recent literature on the role of macrophages and platelets and their interplay in liver fibrosis and hepatocellular carcinoma.

Statins abrogate gemcitabine-induced PD-L1 expression in pancreatic cancer-associated fibroblasts and cancer cells with improved therapeutic outcome

A combination of chemotherapy with immunotherapy has been proposed to have better clinical outcomes in Pancreatic Ductal Adenocarcinoma (PDAC). On the other hand, chemotherapeutics is known to have certain unwanted effects on the tumor microenvironment that may mask the expected beneficial effects of immunotherapy. Here, we have investigated the effect of gemcitabine (GEM), on two immune checkpoint proteins (PD-L1 and PD-L2) expression in cancer associated fibroblasts (CAFs) and pancreatic cancer cells (PCCs). Findings of in vitro studies conducted by using in-culture activated mouse pancreatic stellate cells (mPSCs) and human PDAC patients derived CAFs demonstrated that GEM significantly induces PD-L1 and PD-L2 expression in these cells. Moreover, GEM induced phosphorylation of STAT1 and production of multiple known PD-L1-inducing secretory proteins including IFN-γ in CAFs. Upregulation of PD-L1 in PSCs/CAFs upon GEM treatment caused T cell inactivation and apoptosis in vitro. Importantly, Statins suppressed GEM-induced PD-L1 expression both in CAFs and PCCs while abrogating the inactivation of T-cells caused by GEM-treated PSCs/CAFs. Finally, in an immunocompetent syngeneic orthotopic mouse pancreatic tumor model, simvastatin and GEM combination therapy significantly reduced intra-tumor PD-L1 expression and noticeably reduced the overall tumor burden and metastasis incidence. Together, the findings of this study have provided experimental evidence that illustrates potential unwanted side effects of GEM that could hamper the effectiveness of this drug as mono and/or combination therapy. At the same time the findings also suggest use of statins along with GEM will help in overcoming these shortcomings and warrant further clinical investigation.

Fate tracking reveals differences between Reelin+ hepatic stellate cells (HSCs) and Desmin+ HSCs in activation, migration and proliferation

The activation of hepatic stellate cells (HSCs) is the main cause of liver fibrogenesis in response to different etiologies of chronic liver injuries. HSCs are heterogeneous, but the lack of specific markers to distinguish different HSC subset hinders the development of targeted therapy for liver fibrosis. In this study, we aim to reveal new HSC subsets by cell fate tracking. We constructed a novel ReelinCreERT2 transgenic mouse model to track the fate of cells expressing Reelin and their progeny (Reelin+ cells). And we investigated the property of Reelin+ cells, such as differentiation and proliferation, in hepatotoxic (carbon tetrachloride; CCl4 ) or cholestatic (bile duct ligation; BDL) liver injury models by immunohistochemistry. Our study revealed that Reelin+ cells were a new HSC subset. In terms of activation, migration, and proliferation, Reelin+ HSCs displayed different properties from Desmin+ HSCs (total HSCs) in cholestatic liver injury model but shared similar properties to total HSCs in hepatotoxic liver injury model. Besides, we did not find evidence that Reelin+ HSCs transdifferentiated into hepatocytes or cholangiocytes through mesenchymal-epithelial transition (MET). In this study, our genetic cell fate tracking data reveal that ReelinCreERT2-labelled cells are a new HSC subset, which provides new insights into targeted therapy for liver fibrosis.

Macrophages Serve as Bidirectional Regulators and Potential Therapeutic Targets for Liver Fibrosis

Liver fibrosis is a dynamic pathological process in which the structure and function of the liver abnormally change due to long-term complex inflammatory reactions and chronic liver injury caused by multiple internal and external factors. Previous studies believed that the activation of hepatic stellate cells is a critical part of the occurrence and development of liver fibrosis. However, an increasing number of studies have indicated that the macrophage plays an important role as a central regulator in liver fibrosis, and it directly affects the development and recovery of liver fibrosis. Studies of macrophages and liver fibrosis in the recent 10 years will be reviewed in this paper. This review will not only clarify the molecular mechanism of liver fibrosis regulated by macrophages but also provide new strategies and methods for ameliorating and treating liver fibrosis.

PAK1-dependent mechanotransduction enables myofibroblast nuclear adaptation and chromatin organization during fibrosis

Myofibroblasts are responsible for scarring during fibrosis. The scar propagates mechanical signals inducing a radical transformation in myofibroblast cell state and increasing profibrotic phenotype. Here, we show mechanical stress from progressive scarring induces nuclear softening and de-repression of heterochromatin. The parallel loss of H3K9Me3 enables a permissive state for distinct chromatin accessibility and profibrotic gene regulation. Integrating chromatin accessibility profiles with RNA expression provides insight into the transcription network underlying the switch in profibrotic myofibroblast states, emphasizing mechanoadaptive regulation of PAK1 as key drivers. Through genetic manipulation in liver and lung fibrosis, loss of PAK1-dependent signaling impairs the mechanoadaptive response in vitro and dramatically improves fibrosis in vivo. Moreover, we provide human validation for mechanisms underpinning PAK1-mediated mechanotransduction in liver and lung fibrosis. Collectively, these observations provide insight into the nuclear mechanics driving the profibrotic chromatin landscape in fibrosis, highlighting actomyosin-dependent mechanisms as potential therapeutic targets in fibrosis.

A rat liver cell atlas reveals intrahepatic myeloid heterogeneity

The large size and vascular accessibility of the laboratory rat (Rattus norvegicus) make it an ideal hepatic animal model for diseases that require surgical manipulation. Often, the disease susceptibility and outcomes of inflammatory pathologies vary significantly between strains. This study uses single-cell transcriptomics to better understand the complex cellular network of the rat liver, as well as to unravel the cellular and molecular sources of inter-strain hepatic variation. We generated single-cell and single-nucleus transcriptomic maps of the livers of healthy Dark Agouti and Lewis rat strains and developed a factor analysis-based bioinformatics analysis pipeline to study data covariates, such as strain and batch. Using this approach, we discovered transcriptomic variation within the hepatocyte and myeloid populations that underlie distinct cell states between rat strains. This finding will help provide a reference for future investigations on strain-dependent outcomes of surgical experiment models.

Role of macrophage-to-myofibroblast transition in chronic liver injury and liver fibrosis

BACKGROUND

Chronic liver injury contributes to liver fibrosis, which is characterized by the excessive deposition of extracellular matrix (ECM) components. ECM is mainly composed of myofibroblasts. Recently, macrophage-to-myofibroblasts transition (MMT), has been identified as a novel origin for myofibroblasts. However, the potential functions of MMT in chronic liver injury and liver fibrosis remain unknown.

METHODS

To clarify the transformation of fibrotic cells in hepatic fibrosis, liver specimens were collected from people at different stages in the progression of hepatic fibrosis and stained with immunofluorescence. Models of hepatic fibrosis such as the CCL4 model, HFD-induced NAFLD model, MCD-induced NAFLD model and ethanol-induced AFLD model were demonstrated and were stained with immunofluorescence.

RESULTS

Here, we uncovered macrophages underwent MMT in clinical liver fibrosis tissue samples and multiple animal models of chronic liver injury. MMT cells were found in specimens from patients with liver fibrosis on the basis of co-expression of macrophage (CD68) and myofibroblast (a-SMA) markers. Moreover, macrophages could transform into myofibroblasts in CCL4-induced liver fibrosis model, high-fat diet (HFD) and methionine-choline-deficient diet (MCD)-induced nonalcoholic fatty liver diseases (NAFLD) model, and ethanol-induced alcoholic fatty liver diseases (AFLD) model. In addition, we highlighted that MMT cells mainly had a predominant M2 phenotype in both human and experimental chronic liver injury.

CONCLUSIONS

Taken together, MMT acts a crucial role in chronic liver injury and liver fibrosis.

Chronic liver diseases: From development to novel pharmacological therapies: IUPHAR Review 37

Chronic liver diseases comprise a broad spectrum of burdensome diseases that still lack effective pharmacological therapies. Our research group focuses on fibrosis, which is a major precursor of liver cirrhosis. Fibrosis consists in a progressive disturbance of liver sinusoidal architecture characterised by connective tissue deposition as a reparative response to tissue injury. Multifactorial events and several types of cells participate in fibrosis initiation and progression, and the process still needs to be completely understood. The development of experimental models of liver fibrosis alongside the identification of critical factors progressing fibrosis to cirrhosis will facilitate the development of more effective therapeutic approaches for such condition. This review provides an overlook of the main process leading to hepatic fibrosis and therapeutic approaches that have emerged from a deep knowledge of the molecular regulation of fibrogenesis in the liver. LINKED ARTICLES: This article is part of a themed issue on Translational Advances in Fibrosis as a Therapeutic Target. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v180.22/issuetoc.

Function and biomedical implications of exosomal microRNAs delivered by parenchymal and nonparenchymal cells in hepatocellular carcinoma

Small extracellular vesicles (exosomes) are important components of the tumor microenvironment. They are small membrane-bound vesicles derived from almost all cell types and play an important role in intercellular communication. Exosomes transmit biological molecules obtained from parent cells, such as proteins, lipids, and nucleic acids, and are involved in cancer development. MicroRNAs (miRNAs), the most abundant contents in exosomes, are selectively packaged into exosomes to carry out their biological functions. Recent studies have revealed that exosome-delivered miRNAs play crucial roles in the tumorigenesis, progression, and drug resistance of hepatocellular carcinoma (HCC). In addition, exosomes have great industrial prospects in the diagnosis, treatment, and prognosis of patients with HCC. This review summarized the composition and function of exosomal miRNAs of different cell origins in HCC and highlighted the association between exosomal miRNAs from stromal cells and immune cells in the tumor microenvironment and the progression of HCC. Finally, we described the potential applicability of exosomal miRNAs derived from mesenchymal stem cells in the treatment of HCC.

Liver endothelial cells in NAFLD and transition to NASH and HCC

Non-alcoholic fatty liver disease (NAFLD) is considered as the hepatic manifestation of metabolic syndrome, which is characterised by obesity, insulin resistance, hypercholesterolemia and hypertension. NAFLD is the most frequent liver disease worldwide and more than 10% of NAFLD patients progress to the inflammatory and fibrotic stage of non-alcoholic steatohepatitis (NASH), which can lead to end-stage liver disease including hepatocellular carcinoma (HCC), the most frequent primary malignant liver tumor. Liver sinusoidal endothelial cells (LSEC) are strategically positioned at the interface between blood and hepatic parenchyma. LSECs are highly specialized cells, characterised by the presence of transcellular pores, called fenestrae, and exhibit anti-inflammatory and anti-fibrotic characteristics under physiological conditions. However, during NAFLD development they undergo capillarisation and acquire a phenotype similar to vascular endothelial cells, actively promoting all pathophysiological aspects of NAFLD, including steatosis, inflammation, and fibrosis. LSEC dysfunction is critical for the progression to NASH and HCC while restoring LSEC homeostasis appears to be a promising approach to prevent NAFLD progression and its complications and even reverse tissue damage. In this review we present current information on the role of LSEC throughout the progressive phases of NAFLD, summarising in vitro and in vivo experimental evidence and data from human studies.

Cellular stress in the pathogenesis of nonalcoholic steatohepatitis and liver fibrosis

The burden of chronic liver disease is rising substantially worldwide. Fibrosis, characterized by excessive deposition of extracellular matrix proteins, is the common pathway leading to cirrhosis, and limited treatment options are available. There is increasing evidence suggesting the role of cellular stress responses contributing to fibrogenesis. This Review provides an overview of studies that analyse the role of cellular stress in different cell types involved in fibrogenesis, including hepatocytes, hepatic stellate cells, liver sinusoidal endothelial cells and macrophages.

The Origin and Fate of Liver Myofibroblasts

Liver fibrosis of different etiologies is a serious health problem worldwide. There is no effective therapy available for liver fibrosis except the removal of the underlying cause of injury or liver transplantation. Development of liver fibrosis is caused by fibrogenic myofibroblasts that are not present in the normal liver, but rather activate from liver resident mesenchymal cells in response to chronic toxic or cholestatic injury. Many studies indicate that liver fibrosis is reversible when the causative agent is removed. Regression of liver fibrosis is associated with the disappearance of activated myofibroblasts and resorption of the fibrous scar. In this review, we discuss the results of genetic tracing and cell fate mapping of hepatic stellate cells and portal fibroblasts, their specific characteristics, and potential phenotypes. We summarize research progress in the understanding of the molecular mechanisms underlying the development and reversibility of liver fibrosis, including activation, apoptosis, and inactivation of myofibroblasts.

Isolation of primary human liver cells from normal and nonalcoholic steatohepatitis livers

Here, we present a protocol for isolating human hepatocytes and neural progenitor cells from normal and nonalcoholic steatohepatitis livers. We describe steps for perfusion for scaled-up liver cell isolation and optimization of chemical digestion to achieve maximal yield and cell viability. We then detail a liver cell cryopreservation and potential applications, such as the use of human liver cells as a tool to link experimental and translational research.

Nanoparticle-Mediated RNA Therapy Attenuates Nonalcoholic Steatohepatitis and Related Fibrosis by Targeting Activated Hepatic Stellate Cells

Chronic liver injury and inflammation triggered by metabolic abnormalities initiate the activation of hepatic stellate cells (HSCs), driving fibrosis and parenchymal dysfunction, culminating in disorders such as nonalcoholic steatohepatitis (NASH). Unfortunately, there are currently no approved drugs capable of effectively treating NASH due to the challenges in addressing fibrosis and restoring extracellular matrix (ECM) homeostasis. We discovered a significant up-regulation of interleukin-11 (IL-11) in fibrotic livers using two well-established murine models of NASH. To leverage this signaling pathway, we developed a nanoparticle (NP)-assisted RNA interfering approach that specifically targets activated HSCs (aHSCs), blocking IL-11/ERK signaling to regulate HSC transdifferentiation along with fibrotic remodeling. The most potent NP, designated NP-AEAA, showed enhanced accumulation in fibrotic livers with NASH and was primarily enriched in aHSCs. We further investigated the therapeutic efficacy of aHSC-targeting NP-AEAA encapsulating small interfering RNA (siRNA) against IL11 or its cognate receptor IL11ra1 (termed siIL11@NP-AEAA or siIL11ra1@NP-AEAA, respectively) for resolving fibrosis and NASH. Our results demonstrate that both siIL11@NP-AEAA and siIL11ra1@NP-AEAA effectively inhibit HSC activation and resolve fibrosis and inflammation in two well-established murine models of NASH. Notably, siIL11ra1@NP-AEAA exhibits a superior therapeutic effect over siIL11@NP-AEAA, in terms of reducing liver steatosis and fibrosis as well as recovering liver function. These results constitute a targeted nanoparticulate siRNA therapeutic approach against the IL-11 signaling pathway of aHSCs in the fibrotic liver, offering a promising therapeutic intervention for NASH and other diseases.

Fibroblasts in liver cancer: functions and therapeutic translation

Accumulation of fibroblasts in the premalignant or malignant liver is a characteristic feature of liver cancer, but has not been therapeutically leveraged despite evidence for pathophysiologically relevant roles in tumour growth. Hepatocellular carcinoma is a largely non-desmoplastic tumour, in which fibroblasts accumulate predominantly in the pre-neoplastic fibrotic liver and regulate the risk for hepatocellular carcinoma development through a balance of tumour-suppressive and tumour-promoting mediators. By contrast, cholangiocarcinoma is desmoplastic, with cancer-associated fibroblasts contributing to tumour growth. Accordingly, restoring the balance from tumour-promoting to tumour-suppressive fibroblasts and mediators might represent a strategy for hepatocellular carcinoma prevention, whereas in cholangiocarcinoma, fibroblasts and their mediators could be leveraged for tumour treatment. Importantly, fibroblast mediators regulating hepatocellular carcinoma development might exert opposite effects on cholangiocarcinoma growth. This Review translates the improved understanding of tumour-specific, location-specific, and stage-specific roles of fibroblasts and their mediators in liver cancer into novel and rational therapeutic concepts.

High mesothelin expression by immunohistochemistry predicts improved survival in pleural mesothelioma

AIMS

Mesothelin (MSLN) is a cancer-associated antigen that is overexpressed in malignancies such as mesothelioma, pancreatic and ovarian cancer. It is also a target for novel personalised therapies, including antibodies, antibody-drug conjugates and chimeric antigen receptor T cells. Immunohistochemistry may predict those who would best respond to anti-mesothelin therapies and guide decisions in therapeutic strategy. This study aimed to assess the intensity and distribution of MSLN immunostaining in mesothelioma, and to determine the prognostic value of MSLN expression by histochemical-score (H-score).

METHODS AND RESULTS

The MN1 anti-MSLN antibody was used to stain a formalin-fixed paraffin-embedded tissue microarray of histologically confirmed mesothelioma from 75 consecutive patients who had undergone pleurectomy with or without decortication. MSLN positivity, the staining intensity, distribution of staining and H-score were evaluated. The correlation of H-score with prognosis was investigated. Sixty-six per cent of epithelioid tumours were MSLN-positive (with expression in > 5% tumour cells). Of MSLN-expressing epithelioid tumours, 70.4% had moderate (2+) or strong (3+) intensity MSLN immunostaining, although only 37% of samples had staining in ≥ 50% of tumour cells. In multivariate analysis, MSLN H-score as a continuous variable and an H-score ≥ 33 were independent predictors of improved survival (P = 0.04 and P < 0.001, respectively).

CONCLUSIONS

MSLN expression was more heterogenous in epithelioid mesothelioma than reported previously. Therefore, it would be appropriate to perform an immunohistochemical assessment of MSLN expression to stratify and assess patient suitability for mesothelin-targeted personalised therapies, such as chimeric antigen receptor T cells.

Experimental Models for Studying Structural and Functional State of the Pathological Liver (Review)

Liver pathologies remain one of the leading causes of mortality worldwide. Despite a high prevalence of liver diseases, the possibilities of diagnosing, prognosing, and treating non-alcoholic and alcoholic liver diseases still have a number of limitations and require the development of new methods and approaches. In laboratory studies, various models are used to reconstitute the pathological conditions of the liver, including cell cultures, spheroids, organoids, microfluidic systems, tissue slices. We reviewed the most commonly used in vivo, in vitro, and ex vivo models for studying non-alcoholic fatty liver disease and alcoholic liver disease, toxic liver injury, and fibrosis, described their advantages, limitations, and prospects for use. Great emphasis was placed on the mechanisms of development of pathological conditions in each model, as well as the assessment of the possibility of reconstructing various key aspects of pathogenesis for all these pathologies. There is currently no consensus on the choice of the most adequate model for studying liver pathology. The choice of a certain effective research model is determined by the specific purpose and objectives of the experiment.

Characterization of human stem cell-derived hepatic stellate cells and liver sinusoidal endothelial cells during extended in vitro culture

Background: There is a significant need for predictive and stable in vitro human liver representations for disease modeling and drug testing. Hepatic stellate cells (HSCs) and liver sinusoidal endothelial cells (LSECs) are important non-parenchymal cell components of the liver and are hence of relevance in a variety of disease models, including hepatic fibrosis. Pluripotent stem cell- (PSC-) derived HSCs (scHSCs) and LSECs (scLSECs) offer an attractive alternative to primary human material; yet, the suitability of scHSCs and scLSECs for extended in vitro modeling has not been characterized. Methods: In this study, we describe the phenotypic and functional development of scHSCs and scLSECs during 14 days of 2D in vitro culture. Cell-specific phenotypes were evaluated by cell morphology, immunofluorescence, and gene- and protein expression. Functionality was assessed in scHSCs by their capacity for intracellular storage of vitamin A and response to pro-fibrotic stimuli induced by TGF-β. scLSECs were evaluated by nitric oxide- and factor VIII secretion as well as endocytic uptake of bioparticles and acetylated low-density lipoprotein. Notch pathway inhibition and co-culturing scHSCs and scLSECs were separately tested as options for enhancing long-term stability and maturation of the cells. Results and Conclusion: Both scHSCs and scLSECs exhibited a post-differentiation cell type-specific phenotype and functionality but deteriorated during extended culture with PSC line-dependent variability. Therefore, the choice of PSC line and experimental timeframe is crucial when designing in vitro platforms involving scHSCs and scLSECs. Notch inhibition modestly improved long-term monoculture in a cell line-dependent manner, while co-culturing scHSCs and scLSECs provides a strategy to enhance phenotypic and functional stability.

Role of PDLIM1 in hepatic stellate cell activation and liver fibrosis progression

Liver fibrosis is caused by chronic hepatic injury and may lead to cirrhosis, and even hepatocellular carcinoma. When hepatic stellate cells (HSCs) are activated by liver injury, they transdifferentiate into myofibroblasts, which secrete extracellular matrix proteins that generate the fibrous scar. Therefore, it is extremely urgent to find safe and effective drugs for HSCs activation treatment to prevent liver against fibrosis. Here, we reported that PDZ and LIM domain protein 1 (PDLIM1), a highly conserved cytoskeleton organization regulator, was significantly up-regulated in fibrotic liver tissues and TGF-β-treated HSC-T6 cells. Through transcriptome analysis, we found that knockdown of PDLIM1 resulted in a significant downregulation of genes related to inflammation and immune-related pathways in HSC-T6 cells. Moreover, PDLIM1 knockdown significantly inhibited the activation of HSC-T6 cells and the trans-differentiation of HSC-T6 cells into myofibroblasts. Mechanistically, PDLIM1 is involved in the regulation of TGF-β-mediated signaling pathways in HSCs activation. Thus, targeting PDLIM1 may provide an alternative method to suppress HSCs activation during liver injury. CCCTC-binding factor (CTCF), a master regulator of genome architecture, is upregulated during HSCs activation. PDLIM1 knockdown also indirectly reduced CTCF protein expression, however, CTCF binding to chromatin was not significantly altered by CUT&Tag analysis. We speculate that CTCF may cooperate with PDLIM1 to activate HSCs in other ways. Our results suggest that PDLIM1 can accelerate the activation of HSCs and liver fibrosis progression and could be a potential biomarker for monitoring response to anti-fibrotic therapy.

miR-140-5p attenuates hepatic fibrosis by directly targeting TGFβR1

OBJECTIVE

To explore the protective effect and related mechanism of miR-140-5p on liver fibrosis by interfering with TGF-β/Smad signaling pathway.

METHODS

Liver fibrosis mice models were established by intraperitoneal injection of CCL4. Hematoxylin and eosin (HE) staining was used to detect the structural and morphological changes of the liver. Masson staining was used to detect collagen deposition. Human hepatic stellate cells (HSCs, LX-2) were transfected with miR-140-5p mimic or inhibitor then treated with TGF-β1. The qRT-PCR and Western blotting was used to detect the expression of related molecules. The luciferase reporter assay was used to identify the target of miR-140-5p.

RESULTS

Our results indicated that miR-140-5p expression was downregulated in fibrotic liver tissues of model mice and LX-2 cells treated with TGF-β1. The overexpression of miR-140-5p decreased the expression of collagen1(COL1) and α-smooth muscle actin(α-SMA), inhibited the phosphorylation of Smad-2/3 (pSmad-2/3) in LX-2 cells. Conversely, the knockdown of miR-140-5p upregulated COL1 and α-SMA expression, increased Smad-2/3 phosphorylation. A dual-luciferase reporter assay showed that TGFβR1 was a target gene of miR-140-5p. The overexpression of miR-140-5p suppressed TGFβR1 expression in LX-2 cells. Additionally, knockdown of TGFβR1 decreased the expression of COL1 and α-SMA. Conversely, the overexpression of TGFβR1 reversed the inhibitory effect of miR-140-5p upregulation on expression of COL1 and α-SMA.

CONCLUSION

miR-140-5p bound to TGFβR1 mRNA 3'-untranslated region(3'UTR) and inhibited the expression of TGFβR1, pSmad-2/3, COL1 and α-SMA, thereby exerting a potential therapeutic effect on hepatic fibrosis.

Emergence of highly profibrotic and proinflammatory Lrat+Fbln2+ HSC subpopulation in alcoholic hepatitis

BACKGROUND AND AIMS

Relative roles of HSCs and portal fibroblasts in alcoholic hepatitis (AH) are unknown. We aimed to identify subpopulations of collagen type 1 alpha 1 (Col1a1)-expressing cells in a mouse AH model by single-cell RNA sequencing (scRNA-seq) and filtering the cells with the HSC (lecithin retinol acyltransferase [Lrat]) and portal fibroblast (Thy-1 cell surface antigen [Thy1] and fibulin 2 [Fbln2]) markers and vitamin A (VitA) storage.

APPROACH AND RESULTS

Col1a1-green fluorescent protein (GFP) mice underwent AH, CCl 4 , and bile duct ligation (BDL) procedures to have comparable F1-F2 liver fibrosis. Col1a1-expressing cells were sorted via FACS by VitA autofluorescence and GFP for single-cell RNA sequencing. In AH, approximately 80% of Lrat+Thy1-Fbln2- activated HSCs were VitA-depleted (vs. ~13% in BDL and CCl 4 ). Supervised clustering identified a subset co-expressing Lrat and Fbln2 (Lrat+Fbln2+), which expanded 44-fold, 17-fold, and 1.3-fold in AH, BDL, and CCl 4 . Lrat+Fbln2+ cells had 3-15-times inductions of profibrotic, myofibroblastic, and immunoregulatory genes versus Lrat+Fbln2- cells, but 2-4-times repressed HSC-selective genes. AH activated HSCs had up-regulated inflammatory (chemokine [C-X-C motif] ligand 2 [Cxcl2], chemokine [C-C motif] ligand 2), antimicrobial (Il-33, Zc3h12a), and antigen presentation (H2-Q6, H2-T23) genes versus BDL and CCl 4 . Computational deconvolution of AH versus normal human bulk-liver RNA-sequencing data supported an expansion of LRAT+FBLN2+ cells in AH; AH patient liver immunohistochemistry showed FBLN2 staining along fibrotic septa enriched with LRAT+ cells; and in situ hybridization confirmed co-expression of FBLN2 with CXCL2 and/or human leukocyte antigen E in patient AH. Finally, HSC tracing in Lrat-Cre;Rosa26mTmG mice detected GFP+FBLN2+ cells in AH.

CONCLUSION

A highly profibrotic, inflammatory, and immunoregulatory Lrat+Fbln2+ subpopulation emerges from HSCs in AH and may contribute to the inflammatory and immunoreactive nature of AH.

In Vivo and In Vitro Models to Study Liver Fibrosis: Mechanisms and Limitations

Liver fibrosis is a common result of liver injury owing to various kinds of chronic liver diseases. A deeper understanding of the pathophysiology of liver fibrosis and identifying potential therapeutic targets of liver fibrosis is important because liver fibrosis may progress to advanced liver diseases, such as cirrhosis and hepatocellular carcinoma. Despite numerous studies, the underlying mechanisms of liver fibrosis remain unclear. Mechanisms of the development and progression of liver fibrosis differ according to etiologies. Therefore, appropriate liver fibrosis models should be selected according to the purpose of the study and the type of underlying disease. Many in vivo animal and in vitro models have been developed to study liver fibrosis. However, there are no perfect preclinical models for liver fibrosis. In this review, we summarize the current in vivo and in vitro models for studying liver fibrosis and highlight emerging in vitro models, including organoids and liver-on-a-chip models. In addition, we discuss the mechanisms and limitations of each model.