Fate tracing reveals hepatic stellate cells as dominant contributors to liver fibrosis independent of its aetiology. Nat Commun. 2013;4:2823. [PMID: 24264436 PMCID: PMC4059406 DOI: 10.1038/ncomms3823]

Spatial lipidomics reveals sphingolipid metabolism as anti-fibrotic target in the liver

BACKGROUND AND AIMS

Steatotic liver disease (SLD), which encompasses various causes of fat accumulation in the liver, is a major cause of liver fibrosis. Understanding the specific mechanisms of lipotoxicity, dysregulated lipid metabolism, and the role of different hepatic cell types involved in fibrogenesis is crucial for therapy development.

METHODS

We analysed liver tissue from SLD patients and 3 mouse models. We combined bulk/spatial lipidomics, transcriptomics, imaging mass cytometry (IMC) and analysis of published spatial and single-cell RNA sequencing (scRNA-seq) data to explore the metabolic microenvironment in fibrosis. Pharmacological inhibition of sphingolipid metabolism with myriocin, fumonisin B1, miglustat and D-PDMP was carried out in hepatic stellate cells (HSCs) and human precision cut liver slices (hPCLSs).

RESULTS

Bulk lipidomics revealed increased glycosphingolipids, ether lipids and saturated phosphatidylcholines in fibrotic samples. Spatial lipidomics detected >40 lipid species enriched within fibrotic regions, notably sphingomyelin (SM) 34:1. Using bulk transcriptomics (mouse) and analysis of published spatial transcriptomics data (human) we found that sphingolipid metabolism was also dysregulated in fibrosis at transcriptome level, with increased gene expression for ceramide and glycosphingolipid synthesis. Analysis of human scRNA-seq data showed that sphingolipid-related genes were widely expressed in non-parenchymal cells. By integrating spatial lipidomics with IMC of hepatic cell markers, we found excellent spatial correlation between sphingolipids, such as SM(34:1), and myofibroblasts. Inhibiting sphingolipid metabolism resulted in anti-fibrotic effects in HSCs and hPCLSs.

CONCLUSIONS

Our spatial multi-omics approach suggests cell type-specific mechanisms of fibrogenesis involving sphingolipid metabolism. Importantly, sphingolipid metabolic pathways are modifiable targets, which may have potential as an anti-fibrotic therapeutic strategy.

Hepatic iNKT cells facilitate colorectal cancer metastasis by inducing a fibrotic niche in the liver

The liver is an important metastatic organ that contains many innate immune cells, yet little is known about their role in anti-metastatic defense. We investigated how invariant natural killer T (iNKT) cells influence colorectal cancer-derived liver metastasis using different models in immunocompetent mice. We found that hepatic iNKT cells promote metastasis by creating a supportive niche for disseminated cancer cells. Mechanistically, iNKT cells respond to disseminating cancer cells by producing the fibrogenic cytokines interleukin-4 (IL-4) and IL-13 in a T cell receptor-independent manner. Selective abrogation of IL-4 and IL-13 sensing in hepatic stellate cells prevented their transdifferentiation into extracellular matrix-producing myofibroblasts, which hindered metastatic outgrowth of disseminated cancer cells. This study highlights a novel tumor-promoting axis driven by iNKT cells in the initial stages of metastasis.

Liver portal fibroblasts induce the functions of primary human hepatocytes in vitro

In vitro human liver models are critical to mitigate species-specific differences observed for toxicology, disease modeling, and regenerative medicine. Interactions with mesenchyme (i.e., fibroblasts) can promote phenotypic functions of primary human hepatocytes (PHHs) in culture; however, using liver-derived fibroblasts remains elusive. Portal fibroblasts (PFs) around the portal triad influence bile duct formation during development, but their role in regulating homeostatic hepatic functions remains unknown. Here, we show that human liver PFs induce long-term phenotypic functions in PHHs at higher levels than activated hepatic stellate cells across 2-dimensional and 3-dimensional culture formats. While PF-conditioned media induces some hepatic functions, partly via insulin-like growth factor binding protein-5 signaling, direct contact is necessary to induce optimal functional levels. Inhibiting Notch signaling reduces progenitor-like characteristics of PHHs and further enhances functionality. Overall, this work demonstrates a unique role for PFs in modulating hepatic functions and provides all-human and all-liver coculture strategies for downstream applications.

Coagulin-L alleviates hepatic stellate cells activation and angiogenesis through modulation of the PI3K/AKT pathway during liver fibrosis

Fibrosis, a wound healing response in chronic liver diseases, is a potential therapeutic target during the disease progression. The activation of hepatic stellate cells (HSCs) plays a central role in liver fibrosis and depicts phenotypic change during fibrosis progression. Coagulin-L, a withanolide from Withania coagulans, has shown diverse biological activities, including anti-hyperglycemic and anti-dyslipidemic effects. However, its therapeutic efficacy against HSC activation, pathological angiogenesis and liver fibrosis is unknown. This study investigates the effects of Coagulin-L on HSC activation, pathological angiogenesis and validates these findings in vivo using a methionine and choline-deficient (MCD) diet-induced liver fibrosis model in C57BL/6 mice. Therapeutic efficacy of Coagulin-L was studied using transforming growth factor beta (TGF-β) activated HSC cell line LX-2 in vitro. Network pharmacology was used for target prediction, followed by Human umbilical vein endothelial cells (HUVEC) cell based angiogenic assays. The validation studies were carried out in a mice model of MCD diet induced liver fibrosis using serum biochemistry, histopathological assessment and immunohistochemistry methods. We found that Coagulin-L mitigated TGF-β induced activation of stellate cells and exhibited anti-angiogenic effects by downregulation of vascular endothelial growth factor (VEGF) expression and secretion from stellate cells with inhibition of the PI3K/AKT signaling pathway. In the MCD diet-induced liver fibrosis model, Coagulin-L alleviated liver injury, improved liver function, and reduced collagen deposition. Collectively, our results underscored the anti-fibrotic and anti-angiogenic effects of Coagulin-L in vitro and in vivo liver fibrosis models, thereby indicating its therapeutic potential in chronic liver diseases including metabolic dysfunctional-associated steatohepatitis (MASH).

Lactylation as a metabolic epigenetic modification: Mechanistic insights and regulatory pathways from cells to organs and diseases

In recent years, lactylation, a novel post-translational modification, has demonstrated a unique role in bridging cellular metabolism and epigenetic regulation. This modification exerts a dual-edged effect in both cancer and non-cancer diseases by dynamically integrating the supply of metabolic substrates and the activity of modifying enzymes: on one hand, it promotes tissue homeostasis and repair through the activation of repair genes; on the other, it exacerbates pathological progression by driving malignant phenotypes. In the field of oncology, lactylation regulates key processes such as metabolic reprogramming, immune evasion, and therapeutic resistance, thereby shaping the heterogeneity of the tumor microenvironment. In non-cancerous diseases, including neurodegeneration and cardiovascular disorders, its aberrant activation can lead to mitochondrial dysfunction, fibrosis, and chronic inflammation. Existing studies have revealed a dynamic regulatory network formed by the cooperation of modifying and demodifying enzymes, and have identified mechanisms such as subcellular localization and RNA metabolism intervention that influence disease progression. Nevertheless, several challenges remain in the field. This article comprehensively summarizes the disease-specific regulatory mechanisms of lactylation, with the aim of providing a theoretical foundation for its targeted therapeutic application.

Stromal KITL/SCF Maintains Pancreas Tissue Homeostasis and Restrains Tumor Progression

SIGNIFICANCE

By analyzing transcriptional programs in healthy and tumor-associated pancreatic mesenchyme, we find that a subpopulation of mesenchymal cells in healthy pancreas tissue expresses the paracrine signaling factor KITL. The loss of mesenchymal KITL is an accompanying and permissive feature of pancreas tumor evolution, with potential implications for cancer interception. See related article by Dolskii and Cukierman, p. 872.

Peptidoglycan isolated from the fruit of Lycium barbarum alleviates liver fibrosis in mice by regulating the TGF-β/Smad7 signaling and gut microbiota

The hepatoprotective effect of the fruit of Lycium barbarum has been documented in China over millennia. Lycium barbarum polysaccharides (LBPs) were the first macromolecules reported to mitigate liver fibrosis in carbon tetrachloride (CCl4)-treated mice. Herein, a neutral peptidoglycan, named as LBPW, was extracted from the fruit of Lycium barbarum. In this study, we investigated the hepatoprotective mechanisms of LBPW. CCl4-induced liver fibrosis mice were administered LBPW (50, 100, 200 mg ·kg-1 ·d-1, i.p.) or (100, 200, 300 mg· kg-1 ·d-1, i.g.) for 6 weeks. We showed that either i.p. or i.g. administration of LBPW dose-dependently attenuated liver damage and fibrosis in CCl4-treated mice. Pharmacokinetic analysis showed that cyanine 5.5 amine (Cy5.5)-labeled LBPW (Cy5.5-LBPW) could be detected in the liver through i.p. and i.g. administration with i.g.-administered Cy5.5-LBPW mainly accumulating in the intestine. In TGF-β1-stimulated LX-2 cells as well as in the liver of CCl4-treated mice, we demonstrated that LBPW significantly upregulated Smad7, a negative regulator of TGF-β/Smad signaling, to retard the activation of hepatic stellate cells (HSCs) and prevent liver fibrosis. On the other hand, LBPW significantly boosted the abundance of Akkermansia muciniphila (A. muciniphila) and fortified gut barrier function. We demonstrated that A. muciniphila might be responsible for the efficacy of LBPW since decreasing the abundance of this bacterium by antibiotics (Abs) blocked the effectiveness of LBPW. Overall, our results show that LBPW may exert the hepatoprotective effect via rebalancing TGF-β/Smad7 signaling and propagating gut commensal A. muciniphila, suggesting that LBPW could be leading components to be developed as new drug candidates or nutraceuticals against liver fibrosis.

PLXDC1+ Tumor-Associated Pancreatic Stellate Cells Promote Desmoplastic and Immunosuppressive Niche in Pancreatic Ductal Adenocarcinoma

Pancreatic stellate cells (PSCs) contribute to pancreatic ductal adenocarcinoma (PDAC) progression and therapeutic resistance, yet their detailed functions remain unclear. This study combined RNA sequencing and assay for transposase-accessible chromatin using sequencing (ATAC-seq) on sorted PSCs from adjacent normal and PDAC tissues to investigate their transcriptional and epigenetic activation. PSCs heterogeneity and functions are characterized through bulk, single-cell, and spatial transcriptomes, as well as in situ sequencing. The clinical relevance of PSCs in immunotherapy is assessed using an in-house immune-checkpoint blockade (ICB) treatment cohort. Findings showed that stress and hypoxia signaling activated PSCs in PDAC. Three common PSCs (CPSCs) and four tumor-associated PSCs (TPSCs) are identified, each with distinct functions. CPSCs differentiated into CCL19+ TPSCs in immune-enriched regions, MYH11+ TPSCs in the stromal region, and PLXDC1+ TPSCs, which exhibited cancer-associated myofibroblasts (myCAFs) phenotype linked to poor prognosis. Notably, PLXDC1+ TPSCs, located near aggressive LRRC15+ myCAFs and SPP1+ macrophages, formed a desmoplastic and immunosuppressive niche around the tumor boundary, promoting CD8 T cell exhaustion. Single-cell transcriptomics of PDAC patients treated with ICB revealed that PLXDC1+ TPSCs correlated with poor immunotherapy efficacy. Overall, this study provides key insights into PSCs in PDAC and potential therapeutic targets.

Mdka produced by the activated HSCs drives bipotential progenitor cell redifferentiation during zebrafish biliary-mediated liver regeneration

BACKGROUND AND AIMS

After extensive hepatocyte loss or impaired hepatocyte proliferation, liver regeneration occurs through trans-differentiation of biliary epithelial cells (BECs), which involves dedifferentiation of biliary epithelial cells into bipotential progenitor cells (BP-PCs) and subsequent redifferentiation of BP-PCs into nascent hepatocytes and biliary epithelial cells. Despite several studies on the redifferentiation process of BP-PCs into nascent hepatocytes, the contributions of nonparenchymal cells in this process remain poorly understood.

APPROACH AND RESULTS

Using the zebrafish severe liver injury model, we observed specific expression of midkine a (Mdka) in the activated HSCs through single-cell analyses and fluorescence in situ hybridization. Genetic mutation, pharmacological inhibition, whole-mount in situ hybridizations, and antibody staining demonstrated an essential role of mdka in the redifferentiation of BP-PCs during liver regeneration. Notably, we identified Nucleolin (Ncl), the potential receptor for Mdka, specifically expressed in BP-PCs, and its mutant recapitulated the mdka mutant phenotypes with impaired BP-PC redifferentiation. Mechanistically, the Mdka-Ncl axis drove Erk1 activation in BP-PCs during liver regeneration. Furthermore, overexpression of activated Erk1 partially rescued the defective liver regeneration in the mdka mutant.

CONCLUSIONS

The activated HSCs produce Mdka to drive the redifferentiation process of BP-PCs through activating Erk1 during the biliary-mediated liver regeneration, implying previously unappreciated contributions of nonparenchymal cells to this regeneration process.

Pathophysiological underpinnings of metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is emerging as the leading cause of chronic liver disease worldwide, reflecting the global epidemics of obesity, metabolic syndrome, and type 2 diabetes. Beyond its strong association with excess adiposity, MASLD encompasses a heterogeneous population that includes individuals with normal body weight ("lean MASLD") highlighting the complexity of its pathogenesis. This disease results from a complex interplay between genetic susceptibility, epigenetic modifications, and environmental factors, which converge to disrupt metabolic homeostasis. Adipose tissue dysfunction and insulin resistance trigger an overflow of lipids to the liver, leading to mitochondrial dysfunction, oxidative stress, and hepatocellular injury. These processes promote hepatic inflammation and fibrogenesis, driven by cross talk among hepatocytes, immune cells, and hepatic stellate cells, with key contributions from gut-liver axis perturbations. Recent advances have unraveled pivotal molecular pathways, such as transforming growth factor-β signaling, Notch-induced osteopontin, and sphingosine kinase 1-mediated responses, that orchestrate fibrogenic activation. Understanding these interconnected mechanisms is crucial for developing targeted therapies. This review integrates current knowledge on the pathophysiology of MASLD, emphasizing emerging concepts such as lean metabolic dysfunction-associated steatohepatitis (MASH), epigenetic alterations, hepatic extracellular vesicles, and the relevance of extrahepatic signals. It also discusses novel therapeutic strategies under investigation, aiming to provide a comprehensive and structured overview of the evolving MASLD landscape for both basic scientists and clinicians.

POU6F2 promotes liver metastasis of gastric adenocarcinoma by dual mechanism of transcriptional upregulation of SNAI1 and IGF2/PI3K/AKT signaling-induced conversion of hepatic stellate cells into cancer-associated fibroblasts

BACKGROUND

Activation of cancer-associated fibroblasts (CAFs) plays an important role in tumor metastasis. The purpose of this study is to investigate the role of POU6F2 in conversion of hepatic stellate cells (HSCs) into CAFs in liver metastasis of gastric adenocarcinoma (GAC).

METHODS

POU6F2 expression was examined by real-time PCR, Western blot and immunohistochemical staining. The functional roles of POU6F2 in GAC liver metastasis were investigated both cellular experiments in vitro and in vivo using a mouse model of subcutaneous splenic injection. ChIP and ELISA assays were used to explore the underlying molecular mechanism of POU6F2 in liver metastasis of GAC.

RESULTS

Here we reported that POU6F2 was upregulated in GAC tissue with liver metastasis, which predicted poor early liver metastasis. Upregulating POU6F2 promoted EMT, invasion and migration of GAC cells in vitro, and the liver metastasis of GAC cells in vivo. Mechanic investigation further revealed that upregulating POU6F2 promoted the invasion and metastasis of GAC by transcriptional upregulation of EMT-inducer SNAI1, and promoting the conversion of HSCs into CAFs dependent on transcriptional upregulation of IGF2-induced activation of PI3K/AKT signaling.

CONCLUSION

Our findings uncover a novel dual mechanism by which POU6F2 promotes liver metastasis of GAC.

Extracellular Matrix Microstructures Modulate Hepatic Methionine Cycle and Methylations

The field of mechanobiology has grown in the past decade, but limited studies investigate how the extracellular matrix affects the cell metabolome. The methionine cycle involves the catabolism and regeneration of methionine through the donation and recovery of a single methyl group; this methyl group can methylate DNA, RNA, and proteins to alter gene expression and protein-protein interactions. Through studying cells cultured on fibrous (mimicking healthy extracellular matrice (ECM)) and flat (mimicking severely fibrotic ECM) substrates, we observed an increase in methionine cycle enzyme expression in cells on the flat substrate. We also present how the methionine cycle is modulated by the ECM through transmembrane protein integrin β1. By inhibiting integrin activation through the ligand-mimicking peptide RGD, we observed that the methionine cycle was protected from alteration. The results presented provide insight into possible therapeutic targets for fibrotic diseases and knowledge of mechanisms by which the ECM alters cell processes.

Biomimetic nanoparticles for targeted therapy of liver disease

Liver fibrosis is a progressive and fatal condition characterized by stiffness and scarring of the liver due to excessive buildup of extracellular matrix (ECM) proteins. If left untreated, it can progress to liver cirrhosis and hepatocellular carcinoma (HCC)-one of the fastest-rising causes of cancer mortality in the United States. Despite the increased prevalence of liver fibrosis due to infections, exposure to toxins, and unhealthy lifestyles, there are no effective treatments available. Recent advances in nanomedicine can lead to more targeted and effective strategies for treating liver diseases than existing treatments. In particular, the use of biomimetic nanoparticles (NPs) such as liposomes and cell-membrane-coated NPs is of interest. NPs functionalized with cell membranes mimic the properties of the source cell used and provide inherent immune evasion ability, homologous adhesion, and prolonged circulation. This review explores the types of biomimetic coatings, different cargoes delivered through biomimetic NPs for various treatment modalities, and the type of core NPs used for targeting liver fibrosis and HCC.

AEBP1 or ACLP, which is the key factor in inflammation and fibrosis?

Adipocyte enhancer-binding protein 1 (AEBP1) and Aortic carboxypeptidase-like protein (ACLP) are two protein isoforms produced by the AEBP1 gene. AEBP1, originally discovered in preadipocytes, functions as a transcriptional repressor and is involved in promoting inflammation, proliferation, and migration through various signaling pathways. ACLP is an extracellular matrix protein linked to Ehlers-Danlos syndrome, a genetic disorder characterized by defective connective tissue development. Structurally, AEBP1 and ACLP share many similarities, and both participate in critical physiological or pathological processes, such as cancer and fibrosis, by influencing pathways like NK-κB, WNT, and TGF-β. In recent years, research on AEBP1 and ACLP has expanded to include major organs such as the brain, kidneys, and lungs, with a particular focus on the cardiovascular system, where they show potential as novel drug targets. However, most studies do not clearly distinguish between AEBP1 and ACLP. For instance, AEBP1 is implicated in myocardial fibrosis in hypertrophic cardiomyopathy models, whereas ACLP is associated with fibrosis in other organs. Additionally, literature on the relationship between AEBP1 and fibrosis is often contradictory. Clarifying the distinct roles of AEBP1 and ACLP and their different functions in various cell types would greatly benefit further research. Current research suggests that the AEBP1 gene encodes two proteins, AEBP1 and ACLP, which have been reported to exhibit distinct functions in different studies. However, many studies do not differentiate between these two proteins, potentially leading to misconceptions. Therefore, we have conducted a comprehensive review of the existing literature to elucidate the functions of the AEBP1 gene and its encoded proteins in detail.

Identification of a robust promoter in mouse and human hepatocytes by in vivo biopanning of a barcoded AAV library

Recombinant adeno-associated viruses (AAVs) are leading vectors for in vivo human gene therapy. An integral vector element is promoters, which control transgene expression in either a ubiquitous or cell-type-selective manner. Identifying optimal capsid-promoter combinations is challenging, especially when considering on- versus off-target expression. Here, we report a pipeline for in vivo promoter biopanning in AAV building on our AAV capsid barcoding technology and illustrate its potential by screening 53 promoters in 16 murine tissues using an AAV9 vector. Surprisingly, the 2.2-kb human glial fibrillary acidic protein (GFAP) promoter was the top hit in the liver, where it outperformed robust benchmarks such as the human α-1-antitrypsin promoter or the clinically used liver-specific promoter 1 (LP1). Analysis of hepatic cell populations revealed preferred GFAP promoter activity in hepatocytes. Notably, the GFAP promoter also surpassed the LP1 and cytomegalovirus promoters in human hepatocytes engrafted in an immune-deficient mouse. These findings establish the GFAP promoter as an exciting alternative for research and clinical applications requiring efficient and specific transgene expression in hepatocytes. Our pipeline expands the arsenal of technologies for high-throughput in vivo screening of viral vector components and is compatible with capsid barcoding, facilitating the combinatorial interrogation of complex AAV libraries.

An inverted U-shaped association between high-sensitivity C-reactive protein and the albumin ratio and hepatic steatosis and liver fibrosis: a population-based study

Background

The high-sensitivity C-reactive protein to albumin (CAR) ratio is a comprehensive measure of inflammation in vivo. Hepatic steatosis and fibrosis are significantly correlated with inflammation. The present study aimed to explore the possible associations between CAR and hepatic steatosis and fibrosis in the American population.

Methods

The study population involved the National Health and Nutrition Examination Survey (NHANES) participants from 2017 to 2020. The natural logarithm of CAR, calculated as Ln(CAR) with base "e," was used for further analyses. The relationships between Ln(CAR) and the controlled attenuation parameter (CAP) and between Ln(CAR) and liver stiffness measurement (LSM) were investigated through multivariate linear regression analysis. Interaction and subgroup analysis identified factors affecting these variables. Nonlinear relationships were elucidated by smoothing curves and threshold effect analysis. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the predictive performance of the CAR for non-alcoholic fatty liver disease (NAFLD). The results were adjusted for U.S. population estimates.

Results

The study included a total of 7,404 individuals. Ln(CAR) was positively correlated with CAP in the fully adjusted model, with an effect value of β = 1.827 (95% CI, 0.611, 3.042). A more pronounced positive association was observed among participants with a BMI ≥ 25 kg/m2 in the subgroup analysis. An inverted U-shaped association was shown between Ln(CAR) and CAP through smooth curve fitting and a two-segment linear regression model, with an inflection point of (-9.594). ROC curve analysis showed that CAR had a moderate predictive value for NAFLD (AUC = 0.6895), with a sensitivity of 0.7276 and a specificity of 0.6092. No significant association was detected between Ln(CAR) and the LSM.

Conclusion

We demonstrate an inverted U-shaped relationship between Ln(CAR) and CAP risk within the U.S. demographic. Our results suggest that CAR may serve as a valuable diagnostic tool for NAFLD. Further prospective research is necessary to validate this conclusion.

A Critical Role for the Mitochondrial Pyruvate Carrier in Hepatic Stellate Cell Activation

BACKGROUND & AIMS

Hepatic stellate cells (HSCs) are non-parenchymal cells of the liver that produce the extracellular matrix that forms fibrotic lesions in chronic liver disease, including metabolic dysfunction-associated steatohepatitis (MASH). The mitochondrial pyruvate carrier (MPC) catalyzes the transport of pyruvate from the cytosol into the mitochondrial matrix, which is a critical step in pyruvate metabolism. An MPC inhibitor has shown promise as a novel therapeutic for MASH and HSC activation, but a mechanistic understanding of the direct effects of MPC inhibition on HSC activation is lacking.

METHODS

Stable lines of LX2 cells expressing short hairpin RNA against MPC2 were established and examined in a series of studies to assess HSC metabolism and activation. Mice with conditional, HSC-specific MPC2 deletion were generated and their phenotypes assessed in the context of diets that cause hepatic steatosis, injury, and early-stage fibrosis.

RESULTS

Genetic suppression of MPC activity markedly decreased expression of markers of HSC activation in vitro. MPC knockdown reduced the abundance of several intermediates of the tricarboxylic acid cycle and attenuated HSC activation by suppressing hypoxia inducible factor-1α signaling. Supplementing alpha-ketoglutarate to replenish the tricarboxylic acid cycle intermediates was sufficient to overcome the effects of MPC inhibition on hypoxia inducible factor-1α and HSC activation. On high-fat diets, mice with HSC-specific MPC deletion exhibited reduced circulating transaminases, numbers of HSCs, and hepatic expression of markers of HSC activation and inflammation compared with wild-type mice.

CONCLUSIONS

These data suggest that MPC inhibition modulates HSC metabolism to attenuate activation and illuminate mechanisms by which MPC inhibitors could prove therapeutically beneficial for treating MASH.

Periductal fibroblasts participate in liver homeostasis, fibrosis, and tumorigenesis

Hepatic fibroblasts comprise groups of stromal cells in the liver that are phenotypically distinct from hepatic stellate cells. However, their physiology is poorly understood. By single-cell RNA sequencing, we identified Cd34 and Dpt as hepatic fibroblast-specific genes. Cd34-CreER labeled periportal-venous and periductal fibroblasts, but few pericentral-venous fibroblasts. Cd34+ fibroblasts generated ∼25% of myofibroblasts in periportal fibrosis and ∼40% of cancer-associated fibroblasts (CAFs) in intrahepatic cholangiocarcinoma (ICC). Myofibroblast formation by Cd34+ fibroblasts required Tgfbr2. Depletion of Cd34+ fibroblasts increased the frequency of the ductal epithelial cells under homeostasis and accelerated the progression of ICC. Dpt-CreER labeled periportal- and pericentral-venous fibroblasts, but much less periductal fibroblasts. Dpt+ cells generated ∼15% of myofibroblasts in periportal fibrosis, but few myofibroblasts in pericentral fibrosis or CAFs in ICC. Thus, an orthogonal combination of Cd34-CreER and Dpt-CreER dissected the fates of periductal, periportal-venous, and pericentral-venous fibroblasts. Both periductal and periportal-venous fibroblasts contribute to liver fibrosis. Periductal fibroblasts also contribute to ductal homeostasis and ICC progression.

The transcription factor mesenchyme homeobox 1 exacerbates hepatic fibrosis by transcriptional activation of connective tissue growth factor

As a chronic condition, liver fibrosis is characterized by diverse etiological factors, and the pivotal event to its pathogenesis is the activation of quiescent hepatic stellate cells (HSCs) into myofibroblasts. Mesenchyme homeobox 1 (MEOX1) is a transcription factors central to cellular development and differentiation. However, the role of MEOX1 signaling in hepatic fibrosis still remains largely unknown. In this study, we investigated the potential role and mechanism of MEOX1 in liver fibrosis using different models in vivo and in vitro. The hepatic expression of MEOX1 exhibited a positive correlation with the degree of fibrosis in patients diagnosed with non-alcoholic steatohepatitis (NASH), as determined through bioinformatics analysis. Furthermore, MEOX1 demonstrated high expression levels in activated HSCs and fibrotic liver tissues induced by methionine and choline-deficient diet (MCD), thioacetamide (TAA), or carbon tetrachloride (CCl4) treatment in C57/BL6 mice. Mechanistically, MEOX1 facilitated HSC activation, proliferation, and migration. The comprehensive analysis of transcriptome sequencing and chromatin immunoprecipitation sequencing data revealed that connective tissue growth factor (CTGF) served as a target gene for MEOX1 in HSCs. Specifically, MEOX1 bound to the promoter region of CTGF and enhanced its transcriptional activity, thereby mediating the exacerbating effect of MEOX1 on hepatic fibrosis. In conclusion, our current findings elucidate the role of MEOX1 in exacerbating hepatic fibrosis progression through transcriptional activation of CTGF. Our findings provide valuable insights into the therapeutic potential of targeting MEOX1 for the treatment of hepatic fibrosis.

Hepatic stellate cells control liver zonation, size and functions via R-spondin 3

Hepatic stellate cells (HSCs) have a central pathogenetic role in the development of liver fibrosis. However, their fibrosis-independent and homeostatic functions remain poorly understood1-5. Here we demonstrate that genetic depletion of HSCs changes WNT activity and zonation of hepatocytes, leading to marked alterations in liver regeneration, cytochrome P450 metabolism and injury. We identify R-spondin 3 (RSPO3), an HSC-enriched modulator of WNT signalling, as responsible for these hepatocyte-regulatory effects of HSCs. HSC-selective deletion of Rspo3 phenocopies the effects of HSC depletion on hepatocyte gene expression, zonation, liver size, regeneration and cytochrome P450-mediated detoxification, and exacerbates alcohol-associated and metabolic dysfunction-associated steatotic liver disease. RSPO3 expression decreases with HSC activation and is inversely associated with outcomes in patients with alcohol-associated and metabolic dysfunction-associated steatotic liver disease. These protective and hepatocyte-regulating functions of HSCs via RSPO3 resemble the R-spondin-expressing stromal niche in other organs and should be integrated into current therapeutic concepts.

Exposomal determinants of non-genetic plasticity in tumor initiation

The classical view of cancer as a genetically driven disease has been challenged by recent findings of oncogenic mutations in phenotypically healthy tissues, refocusing attention on non-genetic mechanisms of tumor initiation. In this context, gene-environment interactions take the stage, with recent studies showing how they unleash and redirect cellular and tissue plasticity towards protumorigenic states in response to the exposome, the ensemble of environmental factors impinging on tissue homeostasis. We conceptualize tumor-initiating plasticity as a phenotype-transforming force acting at three levels: cell-intrinsic, focusing on mutant epithelial cells' responses to environmental variation; reprogramming of non-neoplastic cells of the host, leading to protumor micro- and macroenvironments; and microbiome ecosystem dynamics. This perspective highlights cell, tissue, and organismal plasticity mechanisms underlying tumor initiation that are shaped by the exposome, and how their functional investigation may provide new opportunities to prevent, detect, and intercept cancer-promoting plasticity.

Portal Fibrosis and the Ductular Reaction: Pathophysiological Role in the Progression of Liver Disease and Translational Opportunities

A consistent feature of chronic liver diseases and the hallmark of pathologic repair is the so-called "ductular reaction." This is a histologic abnormality characterized by an expansion of dysmorphic cholangiocytes inside and around portal spaces infiltrated by inflammatory, mesenchymal, and vascular cells. The ductular reaction is a highly regulated response based on the reactivation of morphogenetic signaling mechanisms and a complex crosstalk among a multitude of cell types. The nature and mechanism of these exchanges determine the difference between healthy regenerative liver repair and pathologic repair. An orchestrated signaling among cell types directs mesenchymal cells to deposit a specific extracellular matrix with distinct physical and biochemical properties defined as portal fibrosis. Progression of fibrosis leads to vast architectural and vascular changes known as "liver cirrhosis." The signals regulating the ecology of this microenvironment are just beginning to be addressed. Contrary to the tumor microenvironment, immune modulation inside this "benign" microenvironment is scarcely known. One of the reasons for this is that both the ductular reaction and portal fibrosis have been primarily considered a manifestation of cholestatic liver disease, whereas this phenomenon is also present, albeit with distinctive features, in all chronic human liver diseases. Novel human-derived cellular models and progress in "omics" technologies are increasing our knowledge at a fast pace. Most importantly, this knowledge is on the edge of generating new diagnostic and therapeutic advances. Here, we will critically review the latest advances, in terms of mechanisms, pathophysiology, and treatment prospects. In addition, we will delineate future avenues of research, including innovative translational opportunities.

Triclosan exposure induces liver fibrosis in mice: The heterogeneous nuclear ribonucleoprotein A1/pyruvate kinase M2 axis drives hepatic stellate cell activation

Triclosan (TCS) is an effective broad-spectrum antibacterial agent. TCS possesses a stable structure, can easily accumulate in the environment, and may have numerous negative impacts on human health. One organ particularly susceptible to TCS damage is the liver; however, the molecular mechanisms underlying TCS-induced liver damage remain unclear. A long-term TCS exposure model was established in C57BL/6 mice through maternal administration from gestation to postnatal 8-week-old. The offspring were randomly assigned to three groups (0, 50, and 100 mg/kg TCS) with six animals per group, ensuring an equal gender distribution (3 males and 3 females). The results showed that TCS-exposed mice exhibited serum aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase enzyme activities increased by 1.5-2 times when compared with vehicle-treated mice, along with features of liver fibrosis. In the LX-2 cell line, used as an in vitro model, TCS promoted proliferation and migration and induced the activation of hepatic stellate cells (HSCs). The level of pyruvate kinase M2 (PKM2) dimer increased by 200 % in LX-2 cells treated with TCS. PKM2 dimer overexpression stimulated HSC activation, whereas treatment with TEPP-46 (a PKM2 dimer inhibitor) significantly decreased the activation process. The expression of heterogeneous ribonucleoprotein particle A1 (hnRNPA1) was upregulated in the TCS treatment group and promoted the PKM2 expression. Moreover, disruption of the hnRNPA1/PKM2 axis reduced HSC proliferation and migration activated by TCS. Overall, our findings highlighted that TCS could cause liver fibrosis by stimulating the proliferation and migration of HSCs activated via the hnRNPA1/PKM2 axis, providing promising treatment options for TCS-related liver damage.

Hepatic stellate cells regulate liver fatty acid utilization via plasmalemma vesicle-associated protein

The liver is essential for normal fatty acid utilization during fasting. Circulating fatty acids are taken up by hepatocytes and esterified as triacylglycerols for either oxidative metabolization and ketogenesis or export. Whereas the regulation of fatty acid oxidation in hepatocytes is well understood, the uptake and retention of non-esterified fatty acids by hepatocytes is not. Here, we show that murine hepatic stellate cells (HSCs) and their abundantly expressed plasmalemma vesicle-associated protein (PLVAP) control hepatic substrate preference for fasting energy metabolism. HSC-specific ablation of PLVAP in mice elevated hepatic insulin signaling and improved glucose tolerance. Fasted HSC PLVAP knockout mice showed suppressed hepatic fatty acid esterification into di- and triacylglycerols, shifting fasting metabolism from fatty acid oxidation to reliance on carbohydrates. By super-resolution microscopy, we localized HSC PLVAP to caveolae residing along the sinusoidal lumen, supporting a role for HSCs and PLVAP-diaphragmed caveolae in normal fasting metabolism of the liver.

Targeting Hepatic Stellate Cells for the Prevention and Treatment of Liver Cirrhosis and Hepatocellular Carcinoma: Strategies and Clinical Translation

Hepatic stellate cells (HSC) are the major source of myofibroblasts (MFB) in fibrosis and cancer- associated fibroblasts (CAF) in both primary and metastatic liver cancer. Over the past few decades, there has been significant progress in understanding the cellular and molecular mechanisms by which liver fibrosis and HCC occur, as well as the key roles of HSC in their pathogenesis. HSC-targeted approaches using specific surface markers and receptors may enable the selective delivery of drugs, oligonucleotides, and therapeutic peptides that exert optimized anti-fibrotic and anti-HCC effects. Recent advances in omics, particularly single-cell sequencing and spatial transcriptomics, hold promise for identifying new HSC targets for diagnosing and treating liver fibrosis/cirrhosis and liver cancer.

Study on the mechanism of hsa_circ_0074763 regulating the miR-3667-3P/ACSL4 axis in liver fibrosis

This study aimed to investigate the involvement of hsa_circ_0074763 in the activation of HSCs (hepatic stellate cells ) and liver fibrosis. Additionally, it aimed to conduct a preliminary analysis of the molecular mechanism targeting miR-3667-3p/ACSL4 (Long-chain acyl-CoA synthetase 4), thereby providing novel molecular targets for liver fibrosis. The GEO database was utilized to identify differentially expressed hsa_circ_0074763 and determined its subcellular localization in LX-2 cells using fluorescence in situ hybridization. Bioinformatics analysis was employed for result prediction, and the interaction between hsa_circ_0074763 and miR-3667-3P was confirmed using dual-luciferase reporter gene assay. ACSL4 mediated ferroptosis was detected with kit. Hsa_circ_0074763 exhibits high expression levels in the fibrosis model. Validation through dual-luciferase reporter gene assays confirms the interaction between hsa_circ_0074763 and miR-3667-3P. Functional cell experiments demonstrate that overexpression of hsa_circ_0074763 promotes proliferation of LX-2 cells, elevates inflammation levels, and inhibits apoptosis. Additionally, ACSL4 has been identified as a direct target of miR-3667-3P, with overexpression of hsa_circ_0074763 counteracting the inhibitory effect on ACSL4 by suppressing miR-3667-3P. Overexpression of ACSL4 increased the expression levels of ROS (Lipid Oxidation), Iron (Ferro Orange) and MDA (Malondialdehyde), and decreased the expression levels of GPX4 (Glutathione peroxidase 4) and GSH (Glutathione). Our finding suggests that overexpression of hsa_circ_0074763 likely enhances the HSC activation through modulation of the miR-3667-3P/ACSL4 axis. Therefore, hsa_circ_0074763 holds potential as a therapeutic target for liver fibrosis.

Single-cell RNA sequencing advances in revealing the development and progression of MASH: the identifications and interactions of non-parenchymal cells

Developing drugs for the treatment of Metabolic Associated Steatohepatitis (MASH) has always been a significant challenge. Researchers have been dedicated to exploring drugs and therapeutic strategies to alleviate disease progression, but treatments remain limited. This is partly due to the complexity of the pathophysiological processes, and inadequate knowledge of the cellular and molecular mechanisms in MASH. Especially, the liver non-parenchymal cells (NPCs) like Kupffer cells, hepatic stellate cells and sinusoidal endothelial cells which play critical roles in live function, immune responses, fibrosis and disease progression. Deciphering how these cells function in MASH, would help understand the pathophysiological processes and find potential drug targets. In recent years, new technologies have been developed for single-cell transcriptomic sequencing, making cell-specific transcriptome profiling a reality in healthy and diseased livers. In this review, we discussed how the use of single-cell transcriptomic sequencing provided us with an in-depth understanding of the heterogeneous, cellular interactions among non-parenchymal cells and tried to highlight recent discoveries in MASH by this technology. It is hoped that the summarized features and markers of various subclusters in this review could provide a technical reference for further experiments and a theoretical basis for clinical applications.

Systemic aging and aging-related diseases

Aging is a biological process along with systemic and multiple organ dysfunction. It is more and more recognized that aging is a systemic disease instead of a single-organ functional disorder. Systemic aging plays a profound role in multiple diseases including neurodegenerative diseases, cardiovascular diseases, and malignant diseases. Aged organs communicate with other organs and accelerate aging. Skeletal muscle, heart, bone marrow, skin, and liver communicate with each other through organ-organ crosstalk. The crosstalk can be mediated by metabolites including lipids, glucose, short-chain fatty acids (SCFA), inflammatory cytokines, and exosomes. Metabolic disorders including hyperglycemia, hyperinsulinemia, and hypercholesterolemia caused by chronic diseases accelerate hallmarks of aging. Systemic aging leads to the destruction of systemic hemostasis, causes the release of inflammatory cytokines, senescence-associated secretory phenotype (SASP), and the imbalance of microbiota composition. Released inflammatory factors further aggregate senescence, which promotes the aging of multiple solid organs. Targeting senescence or delaying aging is emerging as a critical health strategy for solving age-related diseases, especially in the old population. In the current review, we will delineate the mechanisms of organ crosstalk in systemic aging and age-related diseases to provide therapeutic targets for delaying aging.

A single-nucleus and spatial transcriptomic atlas of the COVID-19 liver reveals topological, functional, and regenerative organ disruption in patients

BACKGROUND

The molecular underpinnings of organ dysfunction in severe COVID-19 and its potential long-term sequelae are under intense investigation. To shed light on these in the context of liver function, we perform single-nucleus RNA-seq and spatial transcriptomic profiling of livers from 17 COVID-19 decedents.

RESULTS

We identify hepatocytes positive for SARS-CoV-2 RNA with an expression phenotype resembling infected lung epithelial cells, and a central role in a pro-fibrotic TGFβ signaling cell-cell communications network. Integrated analysis and comparisons with healthy controls reveal extensive changes in the cellular composition and expression states in COVID-19 liver, providing the underpinning of hepatocellular injury, ductular reaction, pathologic vascular expansion, and fibrogenesis characteristic of COVID-19 cholangiopathy. We also observe Kupffer cell proliferation and erythrocyte progenitors for the first time in a human liver single-cell atlas. Despite the absence of a clinical acute liver injury phenotype, endothelial cell composition is dramatically impacted in COVID-19, concomitantly with extensive alterations and profibrogenic activation of reactive cholangiocytes and mesenchymal cells.

CONCLUSIONS

Our atlas provides novel insights into liver physiology and pathology in COVID-19 and forms a foundational resource for its investigation and understanding.

Primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic biliary inflammation associated with periductular fibrosis of the intrahepatic and extrahepatic bile ducts leading to strictures, bacterial cholangitis, decompensated liver disease and need for liver transplantation. This rare focal liver disease affects all races and ages, with a predominance of young males. There is an up to 88% association with inflammatory bowel disease. Although the aetiology is unknown and the pathophysiology is poorly understood, PSC is regarded as an autoimmune liver disease based on a strong immunogenetic background. Further, the associated risk for various malignancies, particularly cholangiocellular carcinoma, is also poorly understood. No medical therapy has been approved so far nor has been shown to improve transplant-free survival. However, ursodeoxycholic acid is widely used since it improves the biochemical parameters of cholestasis and is safe at low doses. MRI of the biliary tract is the primary imaging technology for diagnosis. Endoscopic interventions of the bile ducts should be limited to clinically relevant strictures for balloon dilatation, biopsy and brush cytology. End-stage liver disease with decompensation is an indication for liver transplantation with recurrent PSC in up to 38% of patients. Several novel therapeutic strategies are in various stages of development, including apical sodium-dependent bile acid transporter and ileal bile acid transporter inhibitors, integrin inhibitors, peroxisome proliferator-activated receptor agonists, CCL24 blockers, recombinant FGF19, CCR2/CCR5 inhibitors, farnesoid X receptor bile acid receptor agonists, and nor-ursodeoxycholic acid. Manipulation of the gut microbiome includes faecal microbiota transplantation. This article summarizes present knowledge and defines unmet medical needs to improve quality of life and survival.

Screening the human druggable genome identifies ABHD17B as an anti-fibrotic target in hepatic stellate cells

Hepatic stellate cells (HSCs) are activated with chronic liver injury and transdifferentiate into myofibroblasts, which produce excessive extracellular matrices that form the fibrotic scar. While the progression of fibrosis is understood to be the cause of end-stage liver disease, there are no approved therapies directed at interfering with the activity of HSC myofibroblasts. Here, we perform a high-throughput small interfering RNA (siRNA) screen in primary human HSC myofibroblasts to identify gene products necessary for the fibrotic phenotype of HSCs. We find that depletion of ABHD17B promotes the inactivation of HSCs, characterized by reduced COL1A1 and ACTA2 expression and accumulation of lipid droplets. Mice deficient in Abhd17b are also protected from fibrosis in the setting of in vivo liver injury. While ABHD17B is a depalmitoylase, our data suggest that ABHD17B promotes fibrosis through pathways independent of depalmitoylation that include interaction with MYO1B to modulate gene expression and HSC migration. Together, our results provide an analysis of the phenotypic consequences for siRNAs targeting RNAs from >9500 genes in primary human HSCs and identify ABHD17B as a potential therapeutic target to inhibit liver fibrosis.

Genetic Loss of HIF-Prolyl-Hydroxylase 1, but Not Pharmacological Inhibition, Mitigates Hepatic Fibrosis

Liver fibrosis is characterized by excessive deposition of extracellular matrix due to chronic inflammation of the liver. Hepatic stellate cells (HSCs) become activated and produce increased amounts of extracellular matrix. Loss of HIF-prolyl-hydroxylase 1 (PHD1) attenuates HSC activation and fibrotic tissue remodeling in a murine model of biliary liver fibrosis. Herein, the protective effect of PHD1 deficiency (PHD1-/-) in an additional (toxic) model of liver fibrosis was validated and the effect of dimethyloxalylglycine (DMOG), a pan-HIF-prolyl-hydroxylase inhibitor, on the development of liver fibrosis, was evaluated. Liver fibrosis was induced utilizing carbon tetrachloride in wild-type (WT) and PHD1-/- mice treated with either vehicle or DMOG. To assess fibrosis development, expression of profibrotic genes in the livers was analyzed by Sirius red staining. When compared with WT mice, PHD1-/- mice developed less-severe liver fibrosis. DMOG treatment did not prevent this liver fibrosis. PHD1-/- mice had fewer α-SMA+ cells and less macrophage infiltration compared with WT mice. Expression of profibrogenic and proinflammatory genes was reduced in livers from carbon tetrachloride-exposed PHD1-/- mice. In vitro analyses of PHD1-deficient human HSCs revealed attenuated mRNA levels of profibrotic genes, as well as impaired migration and invasion. Although PHD1 deficiency attenuated activation of HSCs, pharmacologic PHD inhibition did not ameliorate fibrosis development. These data indicate that selective PHD1 inhibitors could prove effective in preventing and treating liver fibrosis.

Cancer-Associated Fibroblasts in Intrahepatic Cholangiocarcinoma: Insights into Origins, Heterogeneity, Lymphangiogenesis, and Peritoneal Metastasis

Intrahepatic cholangiocarcinoma (iCCA) denotes a rare, highly malignant, and heterogeneous class of primary liver adenocarcinomas exhibiting phenotypic characteristics of cholangiocyte differentiation. Among the distinctive pathological features of iCCA, one that differentiates the most common macroscopic subtype (eg, mass-forming type) of this hepatic tumor from conventional hepatocellular carcinoma is a prominent desmoplastic reaction manifested as a dense fibro-collagenous-enriched tumor stroma. Cancer-associated fibroblasts (CAFs) represent the most abundant mesenchymal cell type in the desmoplastic reaction. Although the protumor effects of CAFs in iCCA have been increasingly recognized, more recent cell lineage tracing studies, advanced single-cell RNA sequencing, and expanded biomarker analyses have provided new awareness into their ontogeny, as well as underscored their biological complexity as reflected by the presence of multiple subtypes. In addition, evidence supports CAFs' potential to display cancer-restrictive roles, including immunosuppression. However, CAFs also play important roles in facilitating metastasis, as exemplified by lymph node metastasis and peritoneal carcinomatosis, which are common in iCCA. Herein, the authors provide a timely appraisal of the origins and phenotypic and functional complexity of CAFs in iCCA, together with providing mechanistic insights into lymphangiogenesis and peritoneal metastasis relevant to this lethal human cancer.

Conserved long noncoding RNA TILAM promotes liver fibrosis through interaction with PML in HSCs

BACKGROUND AND AIMS

Fibrosis is the common end point for all forms of chronic liver injury, and the progression of fibrosis leads to the development of end-stage liver disease. Activation of HSCs and their transdifferentiation into myofibroblasts results in the accumulation of extracellular matrix proteins that form the fibrotic scar. Long noncoding RNAs regulate the activity of HSCs and provide targets for fibrotic therapies.

APPROACH AND RESULTS

We identified long noncoding RNA TILAM located near COL1A1 , expressed in HSCs, and induced with liver fibrosis in humans and mice. Loss-of-function studies in human HSCs and human liver organoids revealed that TILAM regulates the expression of COL1A1 and other extracellular matrix genes. To determine the role of TILAM in vivo, we annotated the mouse ortholog ( Tilam ), generated Tilam- deficient green fluorescent protein-reporter mice, and challenged these mice in 2 different models of liver fibrosis. Single-cell data and analysis of single-data and analysis of Tilam-deficient reporter mice revealed that Tilam is induced in murine HSCs with the development of fibrosis in vivo. Tilam -deficient reporter mice revealed that Tilam is induced in murine HSCs with the development of fibrosis in vivo. Furthermore, loss of Tilam expression attenuated the development of fibrosis in the setting of in vivo liver injury. Finally, we found that TILAM interacts with promyelocytic leukemia nuclear body scaffold protein to regulate a feedback loop by which TGF-β2 reinforces TILAM expression and nuclear localization of promyelocytic leukemia nuclear body scaffold protein to promote the fibrotic activity of HSCs.

CONCLUSIONS

TILAM is activated in HSCs with liver injury and interacts with promyelocytic leukemia nuclear body scaffold protein to drive the development of fibrosis. Depletion of TILAM may serve as a therapeutic approach to combat the development of end-stage liver disease.

Neutrophil extracellular traps promote MASH fibrosis by metabolic reprogramming of HSC

BACKGROUND AND AIMS

Metabolic dysfunction-associated steatohepatitis (MASH) fibrosis is a reversible stage of liver disease accompanied by inflammatory cell infiltration. Neutrophils extrude a meshwork of chromatin fibers to establish neutrophil extracellular traps (NETs), which play important roles in inflammatory response regulation. Our previous work demonstrated that NETs promote HCC in MASH. However, it is still unknown if NETs play a role in the molecular mechanisms of liver fibrosis.

APPROACH AND RESULTS

Following 12 weeks of Western diet/carbon tetrachloride, MASH fibrosis was identified in C57BL/6 mice with increased NET formation. However, NET depletion using DNase I treatment or mice knocked out for peptidyl arginine deaminase type IV significantly attenuated the development of MASH fibrosis. NETs were demonstrated to induce HSCs activation, proliferation, and migration through augmented mitochondrial and aerobic glycolysis to provide additional bioenergetic and biosynthetic supplies. Metabolomic analysis revealed markedly an altered metabolic profile upon NET stimulation of HSCs that were dependent on arachidonic acid metabolism. Mechanistically, NET stimulation of toll-like receptor 3 induced cyclooxygenase-2 activation and prostaglandin E2 production with subsequent HSC activation and liver fibrosis. Inhibiting cyclooxygenase-2 with celecoxib reduced fibrosis in our MASH model.

CONCLUSIONS

Our findings implicate NETs playing a critical role in the development of MASH hepatic fibrosis by inducing metabolic reprogramming of HSCs through the toll-like receptor 3/cyclooxygenase-2/cyclooxygenase-2 pathway. Therefore, NET inhibition may represent an attractive treatment target for MASH liver fibrosis.

Portulaca oleracea L. extract relieve mice liver fibrosis by inhibiting TLR-4/NF-κB, Bcl-2/Bax and TGF-β1/Smad2 signalling transduction

Portulaca oleracea L. are annual herb, which has various pharmacological effects including hepatoprotective property. However, the effect of Portulaca oleracea L. (POL-1) in mice with carbon tetrachloride (CCl4)-induced liver fibrosis and its mechanism of action have not been clarified. POL-1 ameliorated the CCl4-induced liver fibrosis in mice, as shown by decreased collagen deposition and the decreased expression of liver fibrosis marker collagen I and α-smooth muscle actin (α-SMA) mRNA. In addition, treatment with POL-1 suppressed the proliferation of activated human hepatic stellate cell line (LX-2). POL-1 inhibited the oxidative stress and inflammation in fibrotic livers of mice. Mechanistically, POL-1 inhibited the CCl4-induced expression of toll-like receptor-4 (TLR4), myeloid differentiation factor 88 (MyD88), nuclear factor kappa-B (NF-κBp65) p65, Bcl2-associated X (Bax), transforming growth factor-β1 (TGF-β1) and drosophila mothers against decapentaplegic 2 (Smad2) proteins, upregulated B-cell lymphoma -2 (Bcl-2) proteins in livers of mice. These findings suggested that POL-1 attenuated liver fibrosis.

Hepatic Stellate Cells Functional Heterogeneity in Liver Cancer

Hepatic stellate cells (HSCs) are the liver's pericytes, and play key roles in liver homeostasis, regeneration, fibrosis, and cancer. Upon injury, HSCs activate and are the main origin of myofibroblasts and cancer-associated fibroblasts (CAFs) in liver fibrosis and cancer. Primary liver cancer has a grim prognosis, ranking as the third leading cause of cancer-related deaths worldwide, with hepatocellular carcinoma (HCC) being the predominant type, followed by intrahepatic cholangiocarcinoma (iCCA). Moreover, the liver hosts 35% of all metastatic lesions. The distinct spatial distribution and functional roles of HSCs across these malignancies represent a significant challenge for universal therapeutic strategies, requiring a nuanced and tailored understanding of their contributions. This review examines the heterogeneous roles of HSCs in liver cancer, focusing on their spatial localization, dynamic interactions within the tumor microenvironment (TME), and emerging therapeutic opportunities, including strategies to modulate their activity, and harness their potential as targets for antifibrotic and antitumor interventions.

The multi-faceted immune modulatory role of S100A4 in cancer and chronic inflammatory disease

S100A4 is a Ca2+-binding protein involved in multiple chronic inflammatory and neoplastic conditions. This review focuses on recent advances in the understanding of S100A4 function in immune cells, comparing and contrasting S100A4 regulation of immune responses in cancer and chronic inflammatory diseases. We provide evidence that S100A4 regulation of immune cell function has a profound role in promoting the pathogenesis of cancer and pro-inflammatory conditions. Finally, we discuss relevant future directions to target S100A4 therapeutically in different disease states.

IFN-γ-mediated inhibition of JAK/STAT signaling via nano-scutellarin treatment is an efficient strategy for ameliorating liver fibrosis

BACKGROUND

Metabolic dysfunction-associated steatohepatitis (MASH) is a large group of metabolic diseases that are hazardous to human health. Endothelial-to-mesenchymal transition (EndMT) mediated myofibroblast activation is an important factor that aggravates the development of liver fibrosis during MASH. However, the limited understanding of the underlying molecular mechanisms that drive EndMT in MASH has hindered the development of molecularly targeted therapies specifically targeting this pathological process.

METHODS

We employed wild-type and ifn-γ-deficient mice, MASH models were induced repeated CCl4 injections and a high-fat diet to verify the significance of IFN-γ role in vivo and its impact in EndMT. Male mice models of MASH were used to further analyze the effect of Scutellarin@BSA on the improvement of liver fibrosis during MASH in vivo and HUVECs were used to assess IFN-γ effect on EndMT and its interaction with JAK signaling pathway in vitro.

RESULTS

The results showed that IFN-γ is revealed as a key regulator of EndMT during MASH, as evidenced by the significantly lower levels of EndMT and reduced pathological damage in the livers of ifn-γ knockout mice. Furthermore, our research has led to the development of Scutellarin@BSA therapy, which targets and mitigates IFN-γ-driven EndMT, which showed excellent therapeutic effects on EndMT and liver fibrosis in vivo and in vitro during MASH. Mechanistically, IFN-γ can directly bind to the JAK protein and activate downstream STAT1 transcription factors, exerting transcriptional activity and further driving the expression of EndMT-associated proteins. Notably, Scutellarin@BSA treatment effectively diminishes the hallmarks of liver fibrosis by modulating the canonical JAK/STAT1 signaling pathway.

CONCLUSIONS

IFN-γ was identified as a key regulator of EndMT, and Scutellarin@BSA, as an emerging treatment, has been found to effectively inhibit EndMT by directly targeting the regulatory influence of the IFN-γ signaling. This result demonstrates significant therapeutic efficacy in alleviating hepatic fibrosis during MASH, highlighting its great potential as an innovative liver fibrosis treatment.

Metastatic tumor growth in steatotic liver is promoted by HAS2-mediated fibrotic tumor microenvironment

Steatotic liver enhances liver metastasis of colorectal cancer (CRC), but this process is not fully understood. Steatotic liver induced by a high-fat diet increases cancer-associated fibroblast (CAF) infiltration and collagen and hyaluronic acid (HA) production. We investigated the role of HA synthase 2 (HAS2) in the fibrotic tumor microenvironment in steatotic liver using Has2ΔHSC mice, in which Has2 is deleted from hepatic stellate cells. Has2ΔHSC mice had reduced steatotic liver-associated metastatic tumor growth of MC38 CRC cells, collagen and HA deposition, and CAF and M2 macrophage infiltration. We found that low-molecular weight HA activates Yes-associated protein (YAP) in cancer cells, which then releases connective tissue growth factor to further activate CAFs for HAS2 expression. Single-cell analyses revealed a link between CAF-derived HAS2 and M2 macrophages and CRC cells through CD44; these cells were associated with exhausted CD8+ T cells via programmed death-ligand 1 and programmed cell death protein 1 (PD-1). HA synthesis inhibitors reduced steatotic liver-associated metastasis of CRC, YAP expression, and CAF and M2 macrophage infiltration, and improved response to anti-PD-1 antibody. In conclusion, steatotic liver modulates a fibrotic tumor microenvironment to enhance metastatic cancer activity through a bidirectional regulation between CAFs and metastatic tumors, enhancing the metastatic potential of CRC in the liver.

Mechanosignaling via Integrins: Pivotal Players in Liver Fibrosis Progression and Therapy

Liver fibrosis, a consequence of chronic liver injury, represents a major global health burden and is the leading cause of liver failure, morbidity, and mortality. The pathological hallmark of this condition is excessive extracellular matrix deposition, driven primarily by integrin-mediated mechanotransduction. Integrins, transmembrane heterodimeric proteins that serve as primary ECM receptors, orchestrate complex mechanosignaling networks that regulate the activation, differentiation, and proliferation of hepatic stellate cells and other ECM-secreting myofibroblasts. These mechanical signals create self-reinforcing feedback loops that perpetuate the fibrotic response. Recent advances have provided insight into the roles of specific integrin subtypes in liver fibrosis and revealed their regulation of key downstream effectors-including transforming growth factor beta, focal adhesion kinase, RhoA/Rho-associated, coiled-coil containing protein kinase, and the mechanosensitive Hippo pathway. Understanding these mechanotransduction networks has opened new therapeutic possibilities through pharmacological manipulation of integrin-dependent signaling.

Trajectory analysis of hepatic stellate cell differentiation reveals metabolic regulation of cell commitment and fibrosis

Defining the trajectory of cells during differentiation and disease is key for uncovering the mechanisms driving cell fate and identity. However, trajectories of human cells remain largely unexplored due to the challenges of studying them with human samples. In this study, we investigate the proteome trajectory of iPSCs differentiation to hepatic stellate cells (diHSCs) and identify RORA as a key transcription factor governing the metabolic reprogramming of HSCs necessary for diHSCs' commitment, identity, and activation. Using RORA deficient iPSCs and pharmacologic interventions, we show that RORA is required for early differentiation and prevents diHSCs activation by reducing the high energetic state of the cells. While RORA knockout mice have enhanced fibrosis, RORA agonists rescue multi-organ fibrosis in in vivo models. Notably, RORA expression correlates negatively with liver fibrosis and HSCs activation markers in patients with liver disease. This study reveals that RORA regulates cell metabolic plasticity, important for mesoderm differentiation, pericyte quiescence, and fibrosis, influencing cell commitment and disease.

Liver diseases: epidemiology, causes, trends and predictions

As a highly complex organ with digestive, endocrine, and immune-regulatory functions, the liver is pivotal in maintaining physiological homeostasis through its roles in metabolism, detoxification, and immune response. Various factors including viruses, alcohol, metabolites, toxins, and other pathogenic agents can compromise liver function, leading to acute or chronic injury that may progress to end-stage liver diseases. While sharing common features, liver diseases exhibit distinct pathophysiological, clinical, and therapeutic profiles. Currently, liver diseases contribute to approximately 2 million deaths globally each year, imposing significant economic and social burdens worldwide. However, there is no cure for many kinds of liver diseases, partly due to a lack of thorough understanding of the development of these liver diseases. Therefore, this review provides a comprehensive examination of the epidemiology and characteristics of liver diseases, covering a spectrum from acute and chronic conditions to end-stage manifestations. We also highlight the multifaceted mechanisms underlying the initiation and progression of liver diseases, spanning molecular and cellular levels to organ networks. Additionally, this review offers updates on innovative diagnostic techniques, current treatments, and potential therapeutic targets presently under clinical evaluation. Recent advances in understanding the pathogenesis of liver diseases hold critical implications and translational value for the development of novel therapeutic strategies.

Inflammation and Immunity in Liver Neoplasms: Implications for Future Therapeutic Strategies

Over the past two decades, the "hallmarks of cancer" have revolutionized cancer research and highlighted the crucial roles of inflammation and immunity. Protumorigenic inflammation promotes cancer development along with inhibition of antitumor immunity, shaping the tumor microenvironment (TME) toward a tumor-permissive state and further enhancing the malignant potential of cancer cells. This immunosuppressive TME allows tumors to evade immunosurveillance. Thus, understanding the complex interplay between tumors and the immune system within the TME has become pivotal, especially with the advent of immunotherapy. Although immunotherapy has achieved notable success in many malignancies, primary liver cancer, particularly hepatocellular carcinoma, presents unique challenges. The hepatic immunosuppressive environment poses obstacles to the effectiveness of immunotherapy, along with high mortality rates and limited treatment options for patients with liver cancer. In this review, we discuss current understanding of the complex immune-mediated mechanisms underlying liver neoplasms, focusing on hepatocellular carcinoma and liver metastases. We describe the molecular and cellular heterogeneity within the TME, highlighting how this presents unique challenges and opportunities for immunotherapy in liver cancers. By unraveling the immune landscape of liver neoplasms, this review aims to contribute to the development of more effective therapeutic interventions, ultimately improving clinical outcomes for patients with liver cancer.

Cross-Talk Between Tumor Cells and Stellate Cells Promotes Oncolytic VSV Activity in Intrahepatic Cholangiocarcinoma

As the mechanisms underlying tumorigenesis become better understood, the dynamic roles of cellular components of the tumor microenvironment, and their cross-talk with tumor cells, have come to light as key drivers of disease progression and have emerged as important targets of new cancer therapies. In the field of oncolytic virus (OV) therapy, stromal cells have been considered as potential barriers to viral spread, thus limiting virus replication and therapeutic outcome. However, new evidence indicates that intratumoral fibroblasts could support virus replication. We have demonstrated in a rat model of stromal-rich intrahepatic cholangiocarcinoma (CCA) that vesicular stomatitis virus (VSV) can be localized within intratumoral hepatic stellate cells (HSCs), in addition to tumor cells, when the virus was applied via hepatic arterial infusion. Furthermore, VSV was shown to efficiently kill CCA cells and activated HSCs, and co-culture of CCA and HSCs increased viral titers. Interestingly, this effect is also observed when each cell type is cultured alone in a conditioned medium of the other cell type, indicating that secreted cell factors are at least partially responsible for this phenomenon. Partial reduction in sensitivity to type I interferons was observed in co-culture systems, providing a possible mechanism for the increased viral titers. Together, the results indicate that targeting activated HSCs with VSV could provide an additional mechanism of OV therapy, which, until now has not been considered. Furthermore, these findings suggest that VSV is a potentially powerful therapeutic agent for stromal-rich tumors, such as CCA and pancreatic cancer, both of which are very difficult to treat with conventional therapy and have a very poor prognosis.

Identification and functional validation of miR-190b-5p and miR-296-3p as novel therapeutic attenuators of liver fibrosis

BACKGROUND & AIMS

Liver fibrosis and its end-stage form cirrhosis contribute to millions of deaths annually. The lack of robust antifibrotic molecules is in part attributed to the absence of any functional screens to identify molecular regulators using patient-derived primary human hepatic myofibroblasts, which are key drivers of fibrosis.

METHODS

Here, to identify robust regulators of fibrosis, we performed functional microRNA screenings in primary human hepatic myofibroblasts followed by in vivo validation in three independent mouse models of fibrosis (toxin, cholestasis and MASH).

RESULTS

We identified miR-190b-5p and miR-296-3p as robust antifibrotic miRNAs that suppress liver fibrosis. Notably, the expression of miR-190b-5p and miR-296-3p was found to be significantly reduced in human livers with fibrosis. Mechanistically, we discovered hyaluronan synthase 2 (HAS2) and integrin alpha-6 (ITGA6) as novel targets of miR-190b-5p and miR-296-3p, respectively. Furthermore, we demonstrated that the antifibrotic properties of miR-190b-5p and miR-296-3p are, at least in part, dependent on HAS2 and ITGA6. Finally, we showed the antifibrotic function of both miRNAs in a human liver bud model, which mimics multiple features of the human liver.

CONCLUSIONS

Collectively, in our study we discovered miR-190b-5p and miR-296-3p as two novel antifibrotic miRNAs, and that HAS2 and ITGA6 contribute to miR-190b-5p- and miR-296-3p-mediated inhibition of liver fibrosis. These results provide a foundation for future research to explore the clinical utility of miR-190b-5p and miR-296-3p in fibrosis.

IMPACT AND IMPLICATIONS

Liver fibrosis and cirrhosis contribute to millions of deaths worldwide and remain unmet medical needs. In this study, we discovered two microRNAs, miR-190b-5p and miR-296-3p, which suppress liver fibrosis in preclinical mouse models and a human liver bud model. Our promising results encourage further studies that aim to develop both miRNAs for the treatment of liver fibrosis in patients.

RAGE is a key regulator of ductular reaction-mediated fibrosis during cholestasis

Ductular reaction (DR) is the hallmark of cholestatic diseases manifested in the proliferation of bile ductules lined by biliary epithelial cells (BECs). It is commonly associated with an increased risk of fibrosis and liver failure. The receptor for advanced glycation end products (RAGE) was identified as a critical mediator of DR during chronic injury. Yet, the direct link between RAGE-mediated DR and fibrosis as well as the mode of interaction between BECs and hepatic stellate cells (HSCs) to drive fibrosis remain elusive. Here, we delineate the specific function of RAGE on BECs during DR and its potential association with fibrosis in the context of cholestasis. Employing a biliary lineage tracing cholestatic liver injury mouse model, combined with whole transcriptome sequencing and in vitro analyses, we reveal a role for BEC-specific Rage activity in fostering a pro-fibrotic milieu. RAGE is predominantly expressed in BECs and contributes to DR. Notch ligand Jagged1 is secreted from activated BECs in a Rage-dependent manner and signals HSCs in trans, eventually enhancing fibrosis during cholestasis.

Adrenic acid: A promising biomarker and therapeutic target (Review)

Adrenic acid is a 22‑carbon unsaturated fatty acid that is widely present in the adrenal gland, liver, brain, kidney and vascular system that plays a regulatory role in various pathophysiological processes, such as inflammatory reactions, lipid metabolism, oxidative stress, vascular function, and cell death. Adrenic acid is a potential biomarker for various ailments, including metabolic, neurodegenerative and cardiovascular diseases and cancer. In addition, adrenic acid is influenced by the pharmacological properties of several natural products, such as astragaloside IV, evodiamine, quercetin, kaempferol, Berberine‑baicalin and prebiotics, so it is a promising new target for clinical treatment and drug development. However, the molecular mechanisms by which adrenic acid exerts are unclear. The present study systematically reviewed the biosynthesis and metabolism of adrenic acid, focusing on intrinsic mechanisms that influence the progression of metabolic, cardiovascular and neurological disease. These mechanisms regulate several key processes, including immuno‑inflammatory response, oxidative stress, vascular function and cell death. In addition, the present study explored the potential clinical translational value of adrenic acid as a biomarker and therapeutic target. To the best of our knowledge, the present study is first systematic summary of the mechanisms of action of adrenic acid across a range of diseases. The present study provides understanding of the wide range of metabolic activities of adrenic acid and a basis for further exploring the pathogenesis and therapeutic targets of various diseases.

miR-324-3p Suppresses Hepatic Stellate Cell Activation and Hepatic Fibrosis Via Regulating SMAD4 Signaling Pathway

In hepatic fibrosis (HF), hepatic stellate cells (HSCs) form the extracellular matrix (ECM), and the pathological accumulation of ECM in the liver leads to inflammation. Our previous research found that miR-324-3p was down-regulated in culture-activated human HSCs. However, the precise effect of miR-324-3p on HF has not been elucidated. In this study, the HF mouse models were induced through directly injecting carbon tetrachloride (CCl4) into mice; the HF cell models were constructed using TGF-β1-treated LX-2 cells. Next, real-time-quantitative polymerase chain reaction (RT-qPCR), western blot (WB) and immunohistochemistry (IHC) were applied to assess the expression levels of miR-324-3p, α-smooth muscle actin (α-SMA), Vimentin or SMAD4; hematoxylin and eosin (H&E), Masson' s trichrome and Sirius red staining to evaluate the liver injury; luciferase reporter assay to verify the targeting relationship between miR-324-3p and SMAD4; enzyme-linked immunosorbent assay (ELISA) to determine the levels of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST); and cell counting kit-8 (CCK-8) and flow cytometry to evaluate the effects of miR-324-3p on cell proliferation and cycle/apoptosis, respectively. The experimental results showed a reduction in miR-324-3p level in CCl4-induced HF mice as well as transforming growth factor (TGF)-β1-activated HSCs. Interestingly, the miR-324-3p level was rescued following the HF recovery process. In HF mice induced by CCl4, miR-324-3p overexpression inhibited liver tissue damage, decreased serum ALT and AST levels, and inhibited fibrosis-related biomarkers (α-SMA, Vimentin) expression, thereby inhibiting HF. Similarly, miR-324-3p overexpression up-regulated α-SMA and Vimentin levels in HF cells, while knockdown of miR-324-3p had the opposite effect. Besides, miR-324-3p played an antifibrotic role through inhibiting the proliferation of hepatocytes. Further experiments confirmed that miR-324-3p targeted and down-regulated SMAD4 expression. SMAD4 was highly expressed in HF cells, and silencing SMAD4 significantly decreased the α-SMA and Vimentin levels in HF cells. Collectively, the miR-324-3p may suppress the activation of HSCs and HF by targeting SMAD4. Therefore, miR-324-3p is identified as a potential and novel therapeutic target for HF.

Qianggan Ruanjian Pill ameliorates liver fibrosis through regulation of the TGF-β1/Smad and PI3K/AKT signalling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Liver fibrosis is a critical pathological process in the progression of chronic liver injury, ultimately resulting in cirrhosis, for which currently available therapeutic interventions remain inadequate. Among these, the Qianggan Ruanjian Pill (QGRJP) has emerged as a clinically experienced formula with notable therapeutic efficacy against liver fibrosis. However, the precise underlying mechanisms require further investigation.

AIM OF THE STUDY

In this study, we investigated the key pathways and target genes of QGRJP that attenuate liver fibrosis and elucidated the underlying mechanisms.

MATERIALS AND METHODS

High-performance liquid chromatography-mass spectrometry (HPLC-MS) was used to identify the major components of the QGRJP. Mouse models of liver fibrosis were established by injecting olive oil containing 25% carbon tetrachloride (CCl4), which was administered at different doses of QGRJP by gavage. Liver damage and function were assessed using serum biochemical detection, ultrasound imaging, and histopathological examination. The anti-fibrosis effect was assessed using immunohistochemistry, western blotting, and quantitative real-time PCR (qRT-PCR). The in vivo safety of the QGRJP was evaluated using weight monitoring and biopsy. Potential anti-liver fibrosis signalling pathways and key targets of QGRJP were identified using RNA-seq analysis and network pharmacology. The predicted targets and pathways were validated using in vitro and in vivo experiments.

RESULTS

QGRJP significantly ameliorated CCl4-induced liver fibrosis, and its mechanism was correlated with the inhibition of hepatic stellate cell (HSC) activation and the inflammatory response via inhibition of the TGF-β1/Smad and PI3K/AKT pathways, leading to a significant reduction in the expression of collagen and other fibrosis-related proteins. Additionally, no obvious toxic side effects were observed in the major organs of the mice or in activated HSCs (aHSCs).

CONCLUSION

This study demonstrated that QGRJP mitigated liver injury, inflammation, and fibrosis by inhibiting the TGF-β1/Smad and PI3K/AKT signalling pathways.