Initiation of hepatic stellate cell activation extends into chronic liver disease

Precision Strike Strategy for Liver Diseases Trilogy with Xiao-Chai-Hu Decoction: A Meta-Analysis with Machine Learning

BACKGROUND AND PURPOSE

The progression from hepatitis to liver fibrosis (LF) and ultimately to hepatic carcinoma (HCC) represents the advanced stages of various liver diseases. Currently, no universal treatment effectively addresses all three conditions. The Traditional Chinese Medicine formula Xiao-Chai-Hu decoction (XCHD) has shown promise in treating hepatitis, inhibiting LF, and serving as an adjunct therapy for HCC. This study evaluates the efficacy and optimal treatment durations of XCHD in managing these liver diseases using meta-analysis and machine learning techniques.

METHODS

Registered in the PROSPERO database (CRD42024534445), this meta-analysis systematically searched seven databases, including 54 studies with a total of 5,710 patients. Statistical analysis was performed using Stata 17.0. Five machine learning models-Random Forest (RF), XGBoost, Lasso, Multilayer Perceptron (MLP), and a stacking model combining these algorithms-were employed to analyze the data and predict the time-effect relationships. The optimal durations of XCHD treatment for the liver disease trilogy were subsequently projected.

RESULTS

XCHD significantly improved the primary outcome indicators for hepatitis, liver fibrosis, and HCC. Additionally, XCHD demonstrated a beneficial effect on liver dysfunction caused by these diseases. Machine learning predicted the optimal treatment durations of XCHD as 12 weeks for hepatitis, 20.31 weeks for liver fibrosis, and 12 weeks for HCC.

CONCLUSION

XCHD is effective in treating the liver disease trilogy, with optimal treatment durations of 12 weeks for hepatitis and HCC, and 20.31 weeks for liver fibrosis. These findings support the potential of XCHD in developing precise clinical strategies for managing liver diseases. This study innovatively integrates meta-analysis with machine learning to determine the optimal treatment durations, providing a novel approach for evidence-based precision medicine in Traditional Chinese Medicine.

Mixed lineage kinase domain-like protein in liver diseases: Cell-type-specific functions and dual roles

In this letter, we comment on the article by Xuan Yuan et al, published in the recent issue of the World Journal of Gastroenterology. Mixed lineage kinase domain-like protein (MLKL) exhibits cell-type-specific functions in liver parenchymal and non-parenchymal cells, playing dual roles in the pathogenesis of liver diseases. In hepatocytes, MLKL primarily mediates necroptosis and inhibits autophagy, thereby exacerbating liver injury. Conversely, in non-parenchymal liver cells, MLKL modulates inflammatory responses and promotes fibrotic processes, thereby driving disease progression. Notably, MLKL also demonstrates protective functions under specific conditions. For instance, MLKL can inhibit intracellular bacterial replication, promote endosomal trafficking, and facilitate the generation and release of extracellular vesicles, potentially exerting hepatoprotective effects. Understanding these cell-type-specific mechanisms of MLKL action, including its dual roles in promoting injury and providing protection, is crucial for elucidating the complex pathogenesis of liver diseases and developing targeted therapeutic strategies.

Inhibition of MALT1 Protease Attenuates Hepatic Sinusoidal Obstruction Syndrome by Modulating NRF2/HO1 and NF-κB Pathway

BACKGROUND AND PURPOSE

Hepatic sinusoidal obstruction syndrome (HSOS) is a rare liver disorder with potentially life-threatening consequences for colorectal chemotherapy and haematopoietic stem cell transplant recipients. MALT1 (mucous-associated lymphoid tissue lymphoma translocation protein-1) is a protein that plays a key role in the production of inflammatory cytokines, ischemia, atherosclerosis, apoptosis and thromboinflammation; however, its role in HSOS is largely unknown. We aimed to investigate the effect of MALT-1 inhibition in in vitro and in vivo models of HSOS.

EXPERIMENTAL APPROACH

Two mouse models (FOLFOX challenge in immunocompetent and immunocompromised mice) were used to investigate the therapeutic benefits of the MALT-1 inhibitor (MI-2) in vivo. HHSEC, HLEC and RAW-264.7 cells served as in vitro models. HSOS-responsible genes, marker levels and downstream signalling were examined using quantitative real-time PCR, western blot, immunocytochemistry and immunohistochemistry analysis.

KEY RESULTS

In the current investigation, MI-2 significantly reduced FOLFOX-induced HSOS in both mouse models by inhibiting the occlusion of sinusoids, RBC extravasation and bridging fibrosis in liver sections. MI-2 treatment also dramatically reduced specific SOS markers (vWF, VEGF, ephrin, bilirubin and PECAM) and other inflammatory markers. Mechanistic investigation in in vitro models using macrophages, sinusoidal and endothelial cells demonstrated that MI-2 treatment significantly diminished the inflammatory marker levels/expression by lowering ROS production. In addition to the pharmacological approach, siRNA-mediated MALT1 suppression remarkably reduced chemokine and cytokine marker expression in sinusoidal cells.

CONCLUSIONS AND IMPLICATIONS

Thus, our findings demonstrate that MALT1 suppression dramatically reduces FOLFOX-induced inflammatory and fibrotic conditions by modulating the NF-κB activation, paving the way for innovative HSOS therapy approaches.

Inhibition of HSC proliferation and hepatic fibrogenesis with Erythrocyte membrane coated Doxorubicin/Black phosphorus nanosheets

Rapid proliferation underlies the abnormal expansion of activated hepatic stellate cells (aHSCs) and thereby contributes to the development and progression of liver fibrosis, so inhibition of HSC proliferation serves as a good antifibrotic strategy. As a potent topoisomerase II inhibitor, doxorubicin (DOX), an antineoplastic drug, exhibits a significant antifibrotic activity in vitro via retarding the growth of aHSCs and reversing their myofibroblastic phenotype, but its severe hepatotoxicity, cardiotoxicity, and renal toxicity limit its wide clinical application. Therefore, enhancing the specificity and efficacy of DOX in targeting aHSCs to improve its therapeutic index and minimize its adverse effects has become a key point for the success of DOX in antifibrotic treatment. In this study aimed at liver fibrosis treatment, we combined the excellent drug-loading capability and good biocompatibility of black phosphorus nanosheets (BPNSs), the protective and camouflaging properties of red blood cell membrane encapsulation, and the HSCs-targetability provided by the surface modification with vitamin A derivatives, into the construction of HSCs-targeted BP/DOX nanovesicles (BP/DOX@RMV-VA). The obtained DOX nanovesicles exhibited a uniform particle size and spheroid morphology, excellent diffusion property and stability, and high DOX loading. Specifically, they demonstrated outstanding biosafety, effective HSCs-targetability both in vivo and in vitro, and markedly improved pharmacokinetic profile of DOX. BP/DOX@RMV-VA produced strong antiproliferative and MF-phenotype reverting activity both in cultured aHSCs and in mice chronically injured by CCl4. And accordingly, the administration of BP/DOX@RMV-VA to CCl4-injured mice effectively suppressed the expansion of aHSCs and fibrogenesis, and significantly improved liver structure and function without causing detectable cardiotoxicity. These results highly suggest the therapeutic potential of BP/DOX@RMV-VA in treating liver fibrosis and other fibrosis-associated liver diseases.

Danshensu Attenuates Palmitic Acid-Induced Activation of Hepatic Stellate Cells by Regulating Pyroptosis

Introduction: We focused on examining the role of Danshensu in reducing reactive oxygen species (ROS) production and inhibiting NLRP3 inflammasome activation, which are key factors in liver fibrosis and inflammation. We sought to explore the potential of Danshensu as a therapeutic agent for liver fibrosis by targeting the pyroptosis-inflammasome signaling pathway, providing a basis for developing effective and safer NLRP3 inflammasome inhibitors. This study aimed to investigate whether Danshensu can mitigate palmitic acid (PA)-induced activation of hepatic stellate cells (HSCs) by regulating pyroptosis in HSC-T6 and LX-2 cells. Methods: HSC-T6 and LX-2 cell lines served as the cell models. A 2',7'-dichlorofluorescin diacetate reagent was used to measure ROS production within cells. Cell protein extraction was performed using radioimmunoprecipitation assay lysis buffer. The protein concentration in each sample was measured using a BCA assay kit. Western blot analysis was used with the SDS-polyacrylamide gel electrophoresis system. Results: PA-induced activation of HSC-T6 and LX-2 cells by upregulating alpha-smooth muscle actin, integrin-β1, and connective tissue growth factor. Danshensu mitigated PA-induced ROS accumulation in these cells. Moreover, Danshensu potentially reversed the upregulation of NLRP3, cleaved caspase 1, interleukin-1, GSDME, and ASC in PA-activated LX-2 cells via pyroptosis, suggesting its therapeutic potential. Pyroptosis inhibitor tetramethylthiuram disulfide reversed Danshensu attenuated PA activation of HSC-T6 and LX-2 cells, resulting in a 2-fold increase in alpha-smooth muscle actin, integrin-β1, and connective tissue growth factor. Conclusion: Danshensu effectively attenuates PA-induced HSC activation by reducing ROS production and inhibiting pyroptosis, offering a potential therapeutic strategy for liver fibrosis.

Current and emerging strategies for the prevention of hepatocellular carcinoma

Liver cancer is the third leading cause of cancer-related deaths globally, with incident cases expected to rise from 905,700 in 2020 to 1.4 million by 2040. Hepatocellular carcinoma (HCC) accounts for about 80% of all primary liver cancers. Viral hepatitis and chronic excessive alcohol consumption are major risk factors for HCC, but metabolic dysfunction-associated steatotic liver disease is also becoming a dominant cause. The increasing numbers of cases of HCC and changes in risk factors highlight the urgent need for updated and targeted prevention strategies. Preventive interventions encompass strategies to decrease the burden of chronic liver diseases and their progression to HCC. These strategies include nutritional interventions and medications that have shown promise in preclinical models. Although prevailing approaches focus on treating chronic liver disease, leveraging a wider range of interventions represents a promising area to safeguard at-risk populations. In this Review, we explore existing evidence for preventive strategies by highlighting established and potential paths to reducing HCC risk effectively and safely, especially in individuals with chronic liver diseases. We categorize the preventive strategies by the mechanism of action, including anti-inflammatory, antihyperglycaemic, lipid-lowering, nutrition and dietary, antiviral, and antifibrotic pathways. For each category, we discuss the efficacy and safety information derived from mechanistic, translational, observational and clinical trial data, pinpointing knowledge gaps and directions for future research.

Exploring Extracellular Vesicles: A Novel Approach in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) represents an increasing public health concern. The underlying pathophysiological mechanisms of NAFLD remains unclear, and as a result, there is currently no specific therapy for this condition. However, recent studies focus on extracellular vesicles (EVs) as a novelty in their role in cellular communication. An imbalance in the gut microbiota composition may contribute to the progression of NAFLD, making the gut-liver axis a promising target for therapeutic strategies. This review aims to provide a comprehensive overview of EVs in NAFLD. Additionally, exosome-like nanovesicles derived from plants (PELNs) and probiotics-derived extracellular vesicles (postbiotics) have demonstrated the potential to re-establish intestinal equilibrium and modulate gut microbiota, thus offering the potential to alleviate NAFLD via the gut-liver axis. Further research is needed using multiple omics approaches to comprehensively characterize the cargo including protein, metabolites, genetic material packaged, and biological activities of extracellular vesicles derived from diverse microbes and plants.

Flavonoids for gastrointestinal tract local and associated systemic effects: A review of clinical trials and future perspectives

BACKGROUND

Flavonoids are naturally occurring dietary phytochemicals with significant antioxidant effects aside from several health benefits. People often consume them in combination with other food components. Compiling data establishes a link between bioactive flavonoids and prevention of several diseases in animal models, including cardiovascular diseases, diabetes, gut dysbiosis, and metabolic dysfunction-associated steatotic liver disease (MASLD). However, numerous clinical studies have demonstrated the ineffectiveness of flavonoids contradicting rodent models, thereby challenging the validity of using flavonoids as dietary supplements.

AIM OF REVIEW

This review provides a clinical perspective to emphasize the effective roles of dietary flavonoids as well as to summarize their specific mechanisms in animals briefly.

KEY SCIENTIFIC CONCEPTS OF REVIEW

First, this review offers an in-depth elucidation of the metabolic processes of flavonoids within human, encompassing the small, large intestine, and the liver. Furthermore, the review provides a comprehensive overview of the various functions of flavonoids in the gastrointestinal tract, including hindering the breakdown and assimilation of macronutrients, such as polysaccharides and lipids, regulating gut hormone secretion as well as inhibition of mineral iron absorption. In the large intestine, an unabsorbed major portion of flavonoids interact with the gut flora leading to their biotransformation. Once absorbed and circulated in the bloodstream, bioactive flavonoids or their metabolites exert numerous beneficial systemic effects. Lastly, we examine the protective effects of flavonoids in several metabolic disorders, including endothelial dysfunction, MASLD, cardiovascular disease, obesity, hyperlipidemia, and insulin resistance. In conclusion, this review outlines the safety and future prospects of flavonoids in the field of health, especially in the prevention of metabolic syndrome (MetS).

Metabolism of hepatic stellate cells in chronic liver diseases: emerging molecular and therapeutic interventions

Chronic liver diseases, primarily metabolic dysfunction-associated steatotic liver disease (MASLD), metabolic and metabolic dysfunction-associated alcoholic liver disease (MetALD), and viral hepatitis, can lead to liver fibrosis, cirrhosis, and cancer. Hepatic stellate cell (HSC) activation plays a central role in the development of myofibroblasts and fibrogenesis in chronic liver diseases. However, HSC activation is influenced by the complex microenvironments within the liver, which are largely shaped by the interactions between HSCs and various other cell types. Changes in HSC phenotypes and metabolic mechanisms involve glucose, lipid, and cholesterol metabolism, oxidative stress, activation of the unfolded protein response (UPR), autophagy, ferroptosis, senescence, and nuclear receptors. Clinical interventions targeting these pathways have shown promising results in addressing liver inflammation and fibrosis, as well as in modulating glucose and lipid metabolism and metabolic stress responses. Therefore, a comprehensive understanding of HSC phenotypes and metabolic mechanisms presents opportunities for novel therapeutic approaches aimed at halting or even reversing chronic liver diseases.

Hepatic stellate cell single cell atlas reveals a highly similar activation process across liver disease aetiologies

Background & Aims

The progression of chronic liver disease (CLD) is characterized by excessive extracellular matrix deposition, disrupting hepatic architecture and function. Upon liver injury, hepatic stellate cells (HSCs) differentiate towards myofibroblasts and become inflammatory, proliferative and fibrogenic. To date, it is still unclear whether HSC activation is driven by similar mechanisms in different aetiologies.

Methods

HSCs from multiple publicly available single-cell RNA-sequencing datasets were annotated and merged into a single-cell HSC activation atlas. Spheroid co-cultures of primary mouse hepatocytes/HSCs (n = 5) and ELISAs on patient plasma samples (n = 80) were performed to validate the mechanistic insight obtained from the HSC atlas.

Results

We established an HSC activation atlas in which HSCs are clearly divided into three distinct transcriptomic profiles: quiescent HSCs, initiatory HSCs and myofibroblasts. These transcriptomic profiles are present in each of the investigated mouse liver injury models as well as in human CLDs, indicating that HSC activation is a conserved process. This activation process is driven by a core set of transcription factors independent of liver injury or species. Furthermore, we reveal novel ligands associated with activation of HSCs in multiple liver injury models and validate the profibrotic effect of parathyroid hormone. Finally, we identify COLEC10 as a conserved marker for quiescent HSCs and a biomarker of liver fibrosis in patients with different CLDs (p <0.0001).

Conclusions

We reveal unexpected similarities in the regulatory mechanisms of HSCs across diverse liver injury settings and species. The HSC activation atlas has the potential to provide novel insights into liver fibrosis and steer novel treatment options.

Impact and implications

This study establishes a single-cell atlas of hepatic stellate cells across various liver injuries, highlighting a conserved activation process between different injuries and across species. The discovery of novel activating ligands and the biomarker COLEC10 in human plasma could be used to enhance diagnostic and therapeutic strategies. Additionally, the conserved activation process supports the use of any mouse model for mechanistic studies and testing of new anti-fibrotic compounds, streamlining preclinical research efforts.

Yes-associated protein inhibition ameliorates carbon tetrachloride-induced acute liver injury in mice by reducing VDR

Carbon tetrachloride (CCl4) has a wide range of toxic effects, especially causing acute liver injury (ALI), in which rapid compensation for hepatocyte loss ensures liver survival, but proliferation of surviving hepatocytes (known as endoreplication) may imply impaired residual function. Yes-associated protein (YAP) drives hepatocytes to undergo endoreplication and ploidy, the underlying mechanisms of which remain a mystery. In the present study, we uncover during CCl4-mediated ALI accompanied by increased hepatocytes proliferation and YAP activation. Notably, bioinformatics analyses elucidate that hepatic-specific deletion of YAP substantially ameliorated CCl4-induced hepatic proliferation, effectively decreased the vitamin D receptor (VDR) expression. Additionally, a mouse model of acute liver injury substantiated that inhibition of YAP could suppress hepatocytes proliferation via VDR. Furthermore, we also disclosed that the VDR agonist nullifies CCl4-induced ALI alleviated by the YAP inhibitor in vivo. Importantly, hepatocytes were isolated from mice, and it was spotlighted that the anti-proliferative impact of the YAP inhibitor was abolished by the activation of VDR within these hepatocytes. Similarly, primary hepatic stellate cells (HSCs) were isolated and it was manifested that YAP inhibitor suppressed HSC activation via VDR during acute liver injury. Our findings further elucidate the YAP's role in ALI and may provide new avenues for protection against CCl4-drived acute liver injury.

Cysteine sulfenylation contributes to liver fibrosis via the regulation of EphB2-mediated signaling

Sulfenylation is a reversible oxidative posttranslational modification (PTM) of proteins on cysteine residues. Despite the dissection of various biological functions of cysteine sulfenylation, its roles in hepatic fibrosis remain elusive. Here, we report that EphB2, a receptor tyrosine kinase previously implicated in liver fibrosis, is regulated by cysteine sulfenylation during the fibrotic progression of liver. Specifically, EphB2 is sulfenylated at the residues of Cys636 and Cys862 in activated hepatic stellate cells (HSCs), leading to the elevation of tyrosine kinase activity and protein stability of EphB2 and stronger interactions with focal adhesion kinase for the activation of downstream mitogen-activated protein kinase signaling. The inhibitions of both EphB2 kinase activity and cysteine sulfenylation by idebenone (IDE), a marketed drug with potent antioxidant activity, can markedly suppress the activation of HSCs and ameliorate hepatic injury in two well-recognized mouse models of liver fibrosis. Collectively, this study reveals cysteine sulfenylation as a new type of PTM for EphB2 and sheds a light on the therapeutic potential of IDE for the treatment of liver fibrosis.

Stellate cells are in utero markers of pancreatic disease in cystic fibrosis

BACKGROUND

Pancreatic fibrosis is an early diagnostic feature of the common inherited disorder cystic fibrosis (CF). Many people with CF (pwCF) are pancreatic insufficient from birth and the replacement of acinar tissue with cystic lesions and fibrosis is a progressive phenotype that may later lead to diabetes. Little is known about the initiating events in the fibrotic process though it may be a sequela of inflammation in the pancreatic ducts resulting from loss of CFTR impairing normal fluid secretion. Here we use a sheep model of CF (CFTR-/-) to examine the evolution of pancreatic disease through gestation.

METHODS

Fetal pancreas was collected at six time points from 50-days of gestation through to term, which is equivalent to ~ 13 weeks to term in human. RNA was extracted from tissue for bulk RNA-seq and single cells were prepared from 80-day, 120-day and term samples for scRNA-seq. Data were validated by immunochemistry.

RESULTS

Transcriptomic evidence from bulk RNA-seq showed alterations in the CFTR-/- pancreas by 65-days of gestation, which are accompanied by marked pathological changes by 80-days of gestation. These include a fibrotic response, confirmed by immunostaining for COL1A1, αSMA and SPARC, together with acinar loss. Moreover, using scRNA-seq we identify a unique cell population that is significantly overrepresented in the CFTR-/- animals at 80- and 120-days gestation, as are stellate cells at term.

CONCLUSION

The transcriptomic changes and cellular imbalance that we observe likely have pivotal roles in the evolution of CF pancreatic disease and may provide therapeutic opportunities to delay or prevent pancreatic destruction in CF.

Single-Cell Transcriptomic Analysis Revealed the Cell Population Changes and Cell-Cell Communication in the Liver of a Carnivorous Fish in Response to High-Carbohydrate Diet

BACKGROUND

Carnivorous fish have a low carbohydrate utilization ability, and the physiologic and molecular basis of glucose intolerance has not been fully illustrated.

OBJECTIVES

This study aimed to use largemouth bass as a model to investigate the possible mechanism of glucose intolerance in carnivorous fish with the help of single-nuclei RNA sequencing (snRNA-seq).

METHODS

Two diets were formulated, a low-carbohydrate (LC) diet and a high-carbohydrate (HC) diet. The feeding trial lasted for 6 wk, and then, growth performance, biochemical parameters, liver histology, and snRNA-seq were performed.

RESULTS

Growth performance of fish was not affected by the HC diet, while liver glucolipid metabolism disorder and liver injury were observed. A total of 13,247 and 12,848 cells from the liver derived from 2 groups were isolated and sequenced, and 7 major liver cell types were annotated by the marker genes. Hepatocytes and cholangiocytes were lower and hepatic stellate cells (HSCs) and immune cells were higher in the HC group than those in the LC group. Reclustering analysis identified 7 subtypes of hepatocytes and immune cells, respectively. The HSCs showed more cell communication with other cell types, and periportal hepatocytes showed more cell communication with other hepatocyte subtypes. Cell-cell communication mainly focused on cell junction-related signaling pathways. Uncovered by the pseudotime analysis, midzonal hepatocytes were differentiated into 2 major branches-biliary epithelial hepatocytes and hepatobiliary hybrid progenitor. Cell junction and liver fibrosis-related genes were highly expressed in the HC group. HC diet induced the activation of HSCs and, therefore, led to the liver fibrosis of largemouth bass.

CONCLUSIONS

HC diet induces liver glucolipid metabolism disorder and liver injury of largemouth bass. The increase and activation of HSCs might be the main reason for the liver injury. In adaption to HC diet, midzonal hepatocytes differentiates into 2 major branches-biliary epithelial hepatocytes and hepatobiliary hybrid progenitors.

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.

O-GlcNAcylation controls pro-fibrotic transcriptional regulatory signaling in myofibroblasts

Tissue injury causes activation of mesenchymal lineage cells into wound-repairing myofibroblasts (MFs), whose uncontrolled activity ultimately leads to fibrosis. Although this process is triggered by deep metabolic and transcriptional reprogramming, functional links between these two key events are not yet understood. Here, we report that the metabolic sensor post-translational modification O-linked β-D-N-acetylglucosaminylation (O-GlcNAcylation) is increased and required for myofibroblastic activation. Inhibition of protein O-GlcNAcylation impairs archetypal myofibloblast cellular activities including extracellular matrix gene expression and collagen secretion/deposition as defined in vitro and using ex vivo and in vivo murine liver injury models. Mechanistically, a multi-omics approach combining proteomic, epigenomic, and transcriptomic data mining revealed that O-GlcNAcylation controls the MF transcriptional program by targeting the transcription factors Basonuclin 2 (BNC2) and TEA domain transcription factor 4 (TEAD4) together with the Yes-associated protein 1 (YAP1) co-activator. Indeed, inhibition of protein O-GlcNAcylation impedes their stability leading to decreased functionality of the BNC2/TEAD4/YAP1 complex towards promoting activation of the MF transcriptional regulatory landscape. We found that this involves O-GlcNAcylation of BNC2 at Thr455 and Ser490 and of TEAD4 at Ser69 and Ser99. Altogether, this study unravels protein O-GlcNAcylation as a key determinant of myofibroblastic activation and identifies its inhibition as an avenue to intervene with fibrogenic processes.

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.

TM7SF3 controls TEAD1 splicing to prevent MASH-induced liver fibrosis

The mechanisms of hepatic stellate cell (HSC) activation and the development of liver fibrosis are not fully understood. Here, we show that deletion of a nuclear seven transmembrane protein, TM7SF3, accelerates HSC activation in liver organoids, primary human HSCs, and in vivo in metabolic-dysfunction-associated steatohepatitis (MASH) mice, leading to activation of the fibrogenic program and HSC proliferation. Thus, TM7SF3 knockdown promotes alternative splicing of the Hippo pathway transcription factor, TEAD1, by inhibiting the splicing factor heterogeneous nuclear ribonucleoprotein U (hnRNPU). This results in the exclusion of the inhibitory exon 5, generating a more active form of TEAD1 and triggering HSC activation. Furthermore, inhibiting TEAD1 alternative splicing with a specific antisense oligomer (ASO) deactivates HSCs in vitro and reduces MASH diet-induced liver fibrosis. In conclusion, by inhibiting TEAD1 alternative splicing, TM7SF3 plays a pivotal role in mitigating HSC activation and the progression of MASH-related fibrosis.

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.

Therapeutic Potential and Mechanisms of Rosmarinic Acid and the Extracts of Lamiaceae Plants for the Treatment of Fibrosis of Various Organs

Fibrosis, which causes structural hardening and functional degeneration in various organs, is characterized by the excessive production and accumulation of connective tissue containing collagen, alpha-smooth muscle actin (α-SMA), etc. In traditional medicine, extracts of medicinal plants or herbal prescriptions have been used to treat various fibrotic diseases. The purpose of this narrative review is to discuss the antifibrotic effects of rosmarinic acid (RA) and plant extracts that contain RA, as observed in various experimental models. RA, as well as the extracts of Glechoma hederacea, Melissa officinalis, Elsholtzia ciliata, Lycopus lucidus, Ocimum basilicum, Prunella vulgaris, Salvia rosmarinus (Rosmarinus officinalis), Salvia miltiorrhiza, and Perilla frutescens, have been shown to attenuate fibrosis of the liver, kidneys, heart, lungs, and abdomen in experimental animal models. Their antifibrotic effects were associated with the attenuation of oxidative stress, inflammation, cell activation, epithelial-mesenchymal transition, and fibrogenic gene expression. RA treatment activated peroxisomal proliferator-activated receptor gamma (PPARγ), 5' AMP-activated protein kinase (AMPK), and nuclear factor erythroid 2-related factor 2 (NRF2) while suppressing the transforming growth factor beta (TGF-β) and Wnt signaling pathways. Interestingly, most plants that are reported to contain RA and exhibit antifibrotic activity belong to the family Lamiaceae. This suggests that RA is an active ingredient for the antifibrotic effect of Lamiaceae plants and that these plants are a useful source of RA. In conclusion, accumulating scientific evidence supports the effectiveness of RA and Lamiaceae plant extracts in alleviating fibrosis and maintaining the structural architecture and normal functions of various organs under pathological conditions.

The C-type lectin COLEC10 is predominantly produced by hepatic stellate cells and involved in the pathogenesis of liver fibrosis

Hepatic stellate cell is one of the major nonparenchymal cell types in liver. It has been proved the hepatic stellate cells are activated upon liver injury and produce excessive extracellular matrix to induce liver fibrosis. Single-cell RNA sequencing has been introduced to identify the subpopulations and function of hepatic stellate cells for its remarkable resolution of representation of single-cell transcriptome. According to the re-analysis of single-cell RNA sequencing data and pseudotime trajectory inference, we have found the C-type lectins including Colec10 and Colec11 are not produced by hepatocytes but predominantly produced by hepatic stellate cells, especially quiescent ones in the mice livers. In addition, the expression of Colec10 is decreased in the fibrotic livers of CCl4-challenged mice. COLEC10 is also mainly expressed in the hepatic stellate cells of human livers and the expression of COLEC10 is decreased with the progression of liver fibrosis. The bulk RNA sequencing data of the lentivirus transfected LX-2 cells indicates the function of COLEC10 is associated with inflammation, angiogenesis and extracellular matrix alteration. Surprisingly, the in vitro overexpression of COLEC10 in LX-2 cells promotes the mRNA expression of extracellular matrix components including COL1A1, COL1A2 and COL3A1 and the extracellular matrix degradation enzyme MMP2. To further investigate the role of COLEC10 in the pathogenesis of liver fibrosis, the serum concentration of COLEC10 in patients with chronic liver disease and healthy donors is measured. The serum concentration of COLEC10 is elevated in the patients with chronic liver disease compared to the healthy donors and positively correlated with serum concentration of the D-dimer but not the most of liver function markers. Altogether, we conclude that the C-type lectin COLEC10 is predominantly produced by the hepatic stellate cells and involved in the pathogenesis of liver fibrosis.

ADAMTS12 is a stromal modulator in chronic liver disease

Adamalysins, a family of metalloproteinases containing a disintegrin and metalloproteinases (ADAMs) and ADAM with thrombospondin motifs (ADAMTSs), belong to the matrisome and play important roles in various biological and pathological processes, such as development, immunity and cancer. Using a liver cancer dataset from the International Cancer Genome Consortium, we developed an extensive in silico screening that identified a cluster of adamalysins co-expressed in livers from patients with hepatocellular carcinoma (HCC). Within this cluster, ADAMTS12 expression was highly associated with recurrence risk and poorly differentiated HCC signatures. We showed that ADAMTS12 was expressed in the stromal cells of the tumor and adjacent fibrotic tissues of HCC patients, and more specifically in activated stellate cells. Using a mouse model of carbon tetrachloride-induced liver injury, we showed that Adamts12 was strongly and transiently expressed after a 24 h acute treatment, and that fibrosis was exacerbated in Adamts12-null mice submitted to carbon tetrachloride-induced chronic liver injury. Using the HSC-derived LX-2 cell line, we showed that silencing of ADAMTS12 resulted in profound changes of the gene expression program. In particular, genes previously reported to be induced upon HSC activation, such as PAI-1, were mostly down-regulated following ADAMTS12 knock-down. The phenotype of these cells was changed to a less differentiated state, showing an altered actin network and decreased nuclear spreading. These phenotypic changes, together with the down-regulation of PAI-1, were offset by TGF-β treatment. The present study thus identifies ADAMTS12 as a modulator of HSC differentiation, and a new player in chronic liver disease.

Alogliptin exhibits multifaceted effects in thioacetamide-insulted rats: A novel approach to combating hepatic inflammation and fibrogenesis

Hepatic fibrosis arising from chronic liver injury is characterized by dysregulated healing, including hepatic stellate cell activation and excessive deposition of extracellular matrix proteins. Administration of the hepatotoxin thioacetamide (TAA) induces liver injury coupled to fibrogenesis in rodents, mimicking aspects of human disease. Alogliptin is a highly selective inhibitor of dipeptidyl peptidase-4 with purported antifibrotic actions. We investigated the protective effects of alogliptin against TAA-mediated hepatic fibrosis in rats. Adult male Sprague-Dawley rats received intraperitoneal injections of TAA (150 mg/kg) twice weekly for 6 weeks to induce liver fibrosis. A subset of rats also received daily oral alogliptin (20 mg/kg). At 6 weeks, liver injury and fibrosis were assessed by histology, hydroxyproline content, serum liver enzymes, inflammatory cytokines, oxidative stress markers, and genes related to inflammation, apoptosis, and fibrosis. TAA elicited necroinflammation, oxidative stress, upregulation of pro-fibrogenic mediators, increased hydroxyproline content, and excessive collagen deposition, indicating hepatic fibrosis. The administration of Alogliptin led to notable enhancements in liver histology, an extension in survival time, a decrease in hydroxyproline levels and the expression of fibrogenic genes, a reduction in inflammatory cytokines and oxidative stress, and mitigation of hepatocellular apoptosis in rats subjected to TAA treatment. Alogliptin displayed potent antifibrotic, antioxidant, and hepatoprotective properties in this model of toxic liver damage, likely by impeding NFκB while enhanced Nrf2 DNA binding activity which together modulate oxidative stress, inflammation, myofibroblast activation, and apoptosis. These results highlight the potential therapeutic value of alogliptin offering hope for improved treatment of hepatic fibrosis.

Stress mechanism involved in the progression of alcoholic liver disease and the therapeutic efficacy of nanoparticles

Alcoholic liver disease (ALD) poses a significant threat to human health, with excessive alcohol intake disrupting the immunotolerant environment of the liver and initiating a cascade of pathological events. This progressive disease unfolds through fat deposition, proinflammatory cytokine upregulation, activation of hepatic stellate cells, and eventual development of end-stage liver disease, known as hepatocellular carcinoma (HCC). ALD is intricately intertwined with stress mechanisms such as oxidative stress mediated by reactive oxygen species, endoplasmic reticulum stress, and alcohol-induced gut dysbiosis, culminating in increased inflammation. While the initial stages of ALD can be reversible with diligent care and abstinence, further progression necessitates alternative treatment approaches. Herbal medicines have shown promise, albeit limited by their poor water solubility and subsequent lack of extensive exploration. Consequently, researchers have embarked on a quest to overcome these challenges by delving into the potential of nanoparticle-mediated therapy. Nanoparticle-based treatments are being explored for liver diseases that share similar mechanisms with alcoholic liver disease. It underscores the potential of these innovative approaches to counteract the complex pathogenesis of ALD, providing new avenues for therapeutic intervention. Nevertheless, further investigations are imperative to fully unravel the therapeutic potential and unlock the promise of nanoparticle-mediated therapy specifically tailored for ALD treatment.

Stress mechanism involved in the progression of alcoholic liver disease and the therapeutic efficacy of nanoparticles

Alcoholic liver disease (ALD) poses a significant threat to human health, with excessive alcohol intake disrupting the immunotolerant environment of the liver and initiating a cascade of pathological events. This progressive disease unfolds through fat deposition, proinflammatory cytokine upregulation, activation of hepatic stellate cells, and eventual development of end-stage liver disease, known as hepatocellular carcinoma (HCC). ALD is intricately intertwined with stress mechanisms such as oxidative stress mediated by reactive oxygen species, endoplasmic reticulum stress, and alcohol-induced gut dysbiosis, culminating in increased inflammation. While the initial stages of ALD can be reversible with diligent care and abstinence, further progression necessitates alternative treatment approaches. Herbal medicines have shown promise, albeit limited by their poor water solubility and subsequent lack of extensive exploration. Consequently, researchers have embarked on a quest to overcome these challenges by delving into the potential of nanoparticle-mediated therapy. Nanoparticle-based treatments are being explored for liver diseases that share similar mechanisms with alcoholic liver disease. It underscores the potential of these innovative approaches to counteract the complex pathogenesis of ALD, providing new avenues for therapeutic intervention. Nevertheless, further investigations are imperative to fully unravel the therapeutic potential and unlock the promise of nanoparticle-mediated therapy specifically tailored for ALD treatment.

Therapeutic implications of targeting autophagy and TGF-β crosstalk for the treatment of liver fibrosis

Liver fibrosis is characterized by the excessive deposition and accumulation of extracellular matrix components, mainly collagens, and occurs in response to a broad spectrum of triggers with different etiologies. Under stress conditions, autophagy serves as a highly conserved homeostatic system for cell survival and is importantly involved in various biological processes. Transforming growth factor-β1 (TGF-β1) has emerged as a central cytokine in hepatic stellate cell (HSC) activation and is the main mediator of liver fibrosis. A growing body of evidence from preclinical and clinical studies suggests that TGF-β1 regulates autophagy, a process that affects various essential (patho)physiological aspects related to liver fibrosis. This review comprehensively highlights recent advances in our understanding of cellular and molecular mechanisms of autophagy, its regulation by TGF-β, and the implication of autophagy in the pathogenesis of progressive liver disorders. Moreover, we evaluated crosstalk between autophagy and TGF-β1 signalling and discussed whether simultaneous inhibition of these pathways could represent a novel approach to improve the efficacy of anti-fibrotic therapy in the treatment of liver fibrosis.

The Effect of Mesenchymal Stem Cell-Derived Exosomes and miR17-5p Inhibitor on Multicellular Liver Fibrosis Microtissues

Background

Although several studies have been conducted on modeling human liver disease, it is still challenging to mimic nonalcoholic fatty liver disease in vitro. Here, we aimed to develop a fibrotic liver microtissue composed of hepatocytes, hepatic stellate, and endothelial cells. In addition, the therapeutic effects of umbilical cord mesenchymal stem cell-derived exosomes (UC-MSC-EXO) and anti-miR17-5p as new antifibrotic drugs were investigated.

Methods

To create an effective preclinical fibrosis model, multicellular liver microtissues (MLMs) consisting of HepG2, LX2, and HUVECs were cultured and supplemented with a mixture of palmitic acid and oleic acid for 96 hr. Then, MLMs were exposed to UC-MSC-EXO and anti-miR17-5p in different groups. The results of cell viability, reactive oxygen species (ROS) production, liver enzyme levels, inflammation, and histopathology were analyzed to assess the treatment efficacy. Furthermore, the expression of collagen I (COL I) and α-smooth muscle actin (α-SMA) as critical matrix components, transforming growth factor beta (TGF-β), and miR-17-5p were measured.

Results

Free fatty acid supplementation causes fibrosis in MLMs. Our results demonstrated that UC-MSC-EXO and anti-miR17-5p attenuated TGF-β1, interleukin-1β, and interleukin-6 in all experimental groups. According to the suppression of the TGF-β1 pathway, LX2 activation was inhibited, reducing extracellular matrix proteins, including COL I and α-SMA. Also, miR-17-5p expression was elevated in fibrosis conditions. Furthermore, we showed that our treatments decreased alanine aminotransferase and aspartate aminotransferase, and increased albumin levels in the culture supernatant. We also found that both MSC-EXO and MSC-EXO + anti-miR17-5p treatments could reduce ROS production.

Conclusion

Our findings indicated that anti-miR17-5p and MSC-EXO might be promising therapeutic options for treating liver fibrosis. Furthermore, EXO + anti-miR had the best effects on boosting the fibrotic markers. Therefore, we propose this novel MLM model to understand fibrosis mechanisms better and develop new drugs.

Differential Modulation of miR-122 Transcription by TGFβ1/BMP6: Implications for Nonresolving Inflammation and Hepatocarcinogenesis

Chronic inflammation is widely recognized as a significant factor that promotes and worsens the development of malignancies, including hepatocellular carcinoma. This study aimed to explore the potential role of microRNAs in inflammation-associated nonresolving hepatocarcinogenesis. By conducting a comprehensive analysis of altered microRNAs in animal models with liver cancer of various etiologies, we identified miR-122 as the most significantly downregulated microRNA in the liver of animals with inflammation-associated liver cancer. Although previous research has indicated the importance of miR-122 in maintaining hepatocyte function, its specific role as either the trigger or the consequence of underlying diseases remains unclear. Through extensive analysis of animals and in vitro models, we have successfully demonstrated that miR-122 transcription is differentially regulated by the immunoregulatory cytokines, by the transforming growth factor-beta 1 (TGFβ1), and the bone morphogenetic protein-6 (BMP6). Furthermore, we presented convincing evidence directly linking reduced miR-122 transcription to inflammation and in chronic liver diseases. The results of this study strongly suggest that prolonged activation of pro-inflammatory signaling pathways, leading to disruption of cytokine-mediated regulation of miR-122, may significantly contribute to the onset and exacerbation of chronic liver disease.

Chronic-binge ethanol feeding aggravates systemic dyslipidemia in Ldlr-/- mice, thereby accelerating hepatic fibrosis

Objective

Chronic ethanol consumption is known to cause alcohol-associated liver disease, which poses a global health concern as almost a quarter of heavy drinkers develop severe liver damage. Alcohol-induced liver disease ranges from a mild, reversible steatotic liver to alcoholic steatohepatitis and irreversible liver fibrosis and cirrhosis, ultimately requiring liver transplantation. While ethanol consumption is associated with dysregulated lipid metabolism and altered cholesterol homeostasis, the impact of dyslipidemia and pre-existing hypercholesterolemia on the development of alcohol-associated liver disease remains to be elucidated.

Design

To address the influence of systemic dyslipidemia on ethanol-induced liver disease, chronic-binge ethanol feeding was applied to female C57BL/6J (wild type) mice and mice deficient for the low-density lipoprotein receptor (Ldlr-/-), which display a human-like lipoprotein profile with elevated cholesterol and triglyceride levels in circulation. Respective control groups were pair-fed an isocaloric diet.

Results

Chronic-binge ethanol feeding did not alter systemic lipid levels in wild type mice. While increased systemic cholesterol levels in Ldlr-/- mice were not affected by ethanol feeding, chronic-binge ethanol diet aggravated elevated plasma triglyceride levels in Ldlr-/- mice. Despite higher circulatory triglyceride levels in Ldlr-/- mice, hepatic lipid levels and the development of hepatic steatosis were not different from wild type mice after ethanol diet, while hepatic expression of genes related to lipid metabolism (Lpl) and transport (Cd36) showed minor changes. Immunohistochemical assessment indicated a lower induction of infiltrating neutrophils in the livers of ethanol-fed Ldlr-/- mice compared to wild type mice. In line, hepatic mRNA levels of the pro-inflammatory genes Ly6g, Cd11b, Ccr2, Cxcl1 and F4/80 were reduced, indicating less inflammation in the livers of Ldlr-/- mice which was associated with reduced Tlr9 induction. While systemic ALT and hepatic MDA levels were not different, Ldlr-deficient mice showed accelerated liver fibrosis development after chronic-binge ethanol diet than wild type mice, as indicated by increased levels of Sirius Red staining and higher expression of pro-fibrotic genes Tgfb, Col1a1 and Col3a1. Ldlr-/- and wild type mice had similar plasma ethanol levels and did not show differences in the hepatic mRNA levels of Adh1 and Cyp2e1, important for ethanol metabolism.

Conclusion

Our results highlight that chronic-binge ethanol feeding enhances systemic dyslipidemia in Ldlr-/- mice which might accelerate the development of hepatic fibrosis, independent of hepatic lipid levels.

Treatment of liver fibrosis: Past, current, and future

Liver fibrosis accompanies the progression of chronic liver diseases independent of etiologies, such as hepatitis viral infection, alcohol consumption, and metabolic-associated fatty liver disease. It is commonly associated with liver injury, inflammation, and cell death. Liver fibrosis is characterized by abnormal accumulation of extracellular matrix components that are expressed by liver myofibroblasts such as collagens and alpha-smooth actin proteins. Activated hepatic stellate cells contribute to the major population of myofibroblasts. Many treatments for liver fibrosis have been investigated in clinical trials, including dietary supplementation (e.g., vitamin C), biological treatment (e.g., simtuzumab), drug (e.g., pegbelfermin and natural herbs), genetic regulation (e.g., non-coding RNAs), and transplantation of stem cells (e.g., hematopoietic stem cells). However, none of these treatments has been approved by Food and Drug Administration. The treatment efficacy can be evaluated by histological staining methods, imaging methods, and serum biomarkers, as well as fibrosis scoring systems, such as fibrosis-4 index, aspartate aminotransferase to platelet ratio, and non-alcoholic fatty liver disease fibrosis score. Furthermore, the reverse of liver fibrosis is slowly and frequently impossible for advanced fibrosis or cirrhosis. To avoid the life-threatening stage of liver fibrosis, anti-fibrotic treatments, especially for combined behavior prevention, biological treatment, drugs or herb medicines, and dietary regulation are needed. This review summarizes the past studies and current and future treatments for liver fibrosis.

Novel therapeutic avenues for the study of chronic liver disease and regeneration: The foundation of the Iberoamerican Consortium for the study of liver Cirrhosis

Unfortunately, there is a gap of understanding in the pathophysiology of chronic liver disease due to the lack of experimental models that exactly mimic the human disease. Additionally, the diagnosis of patients is very poor due to the lack of biomarkers than can detect the disease in early stages. Thus, it is of utmost interest the generation of a multidisciplinary consortium from different countries with a direct translation. The present reports the meeting of the 2021 Iberoamerican Consortium for the study of liver Cirrhosis, held online, in October 2021. The meeting, was focused on the recent advancements in the field of chronic liver disease and cirrhosis with a specific focus on cell pathobiology and liver regeneration, molecular and cellular targets involved in non-alcoholic hepatic steatohepatitis, alcoholic liver disease (ALD), both ALD and western diet, and end-stage liver cirrhosis and hepatocellular carcinoma. In addition, the meeting highlighted recent advances in targeted novel technology (-omics) and opening therapeutic avenues in this field of research.

Autophagy Inhibitor Chloroquine Downmodulates Hepatic Stellate Cell Activation and Liver Damage in Bile-Duct-Ligated Mice

Hepatic stellate cell (HSC) activation via the autophagy pathway is a critical factor in liver fibrogenesis. This study tests the hypothesis that chloroquine (CQ) treatment can prevent autophagy and HSC activation in vitro and in vivo in bile-duct-ligated (BDL) mice. Sham-operated and BDL mice were treated with either PBS or CQ in two 60 mg/kg doses the day (D) before and after surgery. On day 2 (2D), HSCs were isolated, and their biological activities were evaluated by measuring intracellular lipid content, α-sma/collagen, and expression of autophagy lc3, sqstm1/p62 markers. The treatment efficacy on liver function was evaluated with serum albumin, transaminases (AST/ALT), and hepatic histology. Primary HSCs were treated in vitro for 24 h with CQ at 0, 2.5, 5, 10, 30, and 50 µM. Autophagy and HSC activation were assessed after 2D of treatment. CQ treatment improved serum AST/ALT, albumin, and bile duct proliferation in 2D BDL mice. This is associated with a suppression of HSC activation, shown by higher HSC lipid content and collagen I staining, along with the blockage of HSC autophagy indicated by an increase in p62 level and reduction in lc3 staining. CQ 5 µM inhibited autophagy in primary HSCs in vitro by increasing p62 and lc3 accumulation, thereby suppressing their in vitro activation. The autophagy inhibitor CQ reduced HSC activation in vitro and in vivo. CQ improved liver function and reduced liver injury in BDL mice.

ScRNA-seq and ST-seq in liver research

Spatial transcriptomics, which combine gene expression data with spatial information, has quickly expanded in recent years. With application of this method in liver research, our knowledge about liver development, regeneration, and diseases have been greatly improved. While this field is moving forward, a variety of problems still need to be addressed, including sensitivity, limited capacity to obtain exact single-cell information, data processing methods, as well as others. Methods like single-cell RNA sequencing (scRNA-seq) are usually used together with spatial transcriptome sequencing (ST-seq) to clarify cell-specific gene expression. In this review, we explore how advances of scRNA-seq and ST-seq, especially ST-seq, will pave the way to new opportunities to investigate fundamental questions in liver research. Finally, we will discuss the strengths, limitations, and future perspectives of ST-seq in liver research.

Generation and Culture of Primary Mouse Hepatocyte-Hepatic Stellate Cell Spheroids

In vitro models of liver fibrosis have evolved from mono-cultures of primary rodent hepatic stellate cells and stellate cell lines, to more complex co-cultures of primary or stem cell-derived liver cells. Great progress has been made in the development of stem cell-derived liver cultures; however, the liver cells obtained from stem cells do not yet fully recapitulate the phenotype of their in vivo counterparts. Freshly isolated rodent cells remain the most representative cell type to use for in vitro culture. To study liver injury-induced fibrosis, co-cultures of hepatocytes and stellate cells are an informative minimal model. Here, we describe a robust protocol to isolate hepatocytes and hepatic stellate cells from one mouse and a method for the subsequent seeding and culture as free-floating spheroids.

Intercellular communication among liver cells in the perisinusoidal space of the injured liver: Pathophysiology and therapeutic directions

Hepatic stellate cells (HSCs) in the perisinusoidal space are surrounded by hepatocytes, liver sinusoidal endothelial cells, Kupffer cells, and other resident immune cells. In the normal liver, HSCs communicate with these cells to maintain normal liver functions. However, after chronic liver injury, injured hepatocytes release several proinflammatory mediators, reactive oxygen species, and damage-associated molecular patterns into the perisinusoidal space. Consequently, such alteration activates quiescent HSCs to acquire a myofibroblast-like phenotype and express high amounts of transforming growth factor-β1, angiopoietins, vascular endothelial growth factors, interleukins 6 and 8, fibril forming collagens, laminin, and E-cadherin. These phenotypic and functional transdifferentiation lead to hepatic fibrosis with a typical abnormal extracellular matrix synthesis and disorganization of the perisinusoidal space of the injured liver. Those changes provide a favorable environment that regulates tumor cell proliferation, migration, adhesion, and survival in the perisinusoidal space. Such tumor cells by releasing transforming growth factor-β1 and other cytokines, will, in turn, activate and deeply interact with HSCs via a bidirectional loop. Furthermore, hepatocellular carcinoma-derived mediators convert HSCs and macrophages into protumorigenic cell populations. Thus, the perisinusoidal space serves as a critical hub for activating HSCs and their interactions with other cell types, which cause a variety of liver diseases such as hepatic inflammation, fibrosis, cirrhosis, and their complications, such as portal hypertension and hepatocellular carcinoma. Therefore, targeting the crosstalk between activated HSCs and tumor cells/immune cells in the tumor microenvironment may also support a promising therapeutic strategy.

Improved Precision-Cut Liver Slice Cultures for Testing Drug-Induced Liver Fibrosis

In vitro models of human liver disease often fail to mimic the complex 3D structures and cellular organizations found in vivo. Precision cut liver slices (PCLS) retain the complex physiological architecture of the native liver and therefore could be an exceptional in vitro liver model. However, the production of PCLS induces a spontaneous culture-induced fibrogenic reaction, limiting the application of PCLS to anti-fibrotic compounds. Our aim was to improve PCLS cultures to allow compound-induced fibrosis induction. Hepatotoxicity in PCLS cultures was analyzed by lactate dehydrogenase leakage and albumin secretion, while fibrogenesis was analyzed by qRT-PCR and western blot for hepatic stellate cell (HSC) activation markers and collagen 6 secretion by enzyme-linked immunosorbent assays (ELISA). We demonstrate that supplementation of 3 mm mouse PCLS cultures with valproate strongly reduces fibrosis and improves cell viability in our PCLS cultures for up to 5 days. Fibrogenesis can still be induced both directly and indirectly through exposure to TGFβ and the hepatotoxin acetaminophen, respectively. Finally, human PCLS cultures showed similar but less robust results. In conclusion, we optimized PCLS cultures to allow for drug-induced liver fibrosis modeling.