Hepatic Stellate Cell Activation and Inactivation in NASH-Fibrosis-Roles as Putative Treatment Targets?

Preclinical targeting of liver fibrosis with a 89Zr-labeled Fibrobody® directed against platelet derived growth factor receptor-β

PURPOSE

Hepatic fibrosis develops as a response to chronic liver injury, resulting in the formation of fibrous scars. This process is initiated and driven by collagen-producing activated myofibroblasts which reportedly express high levels of platelet derived growth factor receptor-β (PDGFRβ). We therefore regard PDGFRβ as an anchor for diagnosis and therapy. The Fibrobody® SP02SP26-ABD is a biparatopic VHH-construct targeting PDGFRβ. Here, we explore its potential as a theranostic vector for liver fibrosis.

METHODS

Specificity, cross-species binding, and cellular uptake of SP02SP26-ABD was assessed using human, mouse and rat PDGFRβ ectodomains and PDGFRβ-expressing cells. Cellular uptake by PDGFRβ-expressing cells was also evaluated by equipping the Fibrobody® with auristatinF and reading out in vitro cytotoxicity. The validity of PDGFRβ as a marker for active fibrosis was confirmed in human liver samples and 3 mouse models of liver fibrosis (DDC, CCl4, CDA-HFD) through immunohistochemistry and RT-PCR. After radiolabeling of DFO*-SP02SP26-ABD with 89Zr, its in vivo targeting ability was assessed in healthy mice and mice with liver fibrosis by PET-CT imaging, ex vivo biodistribution and autoradiography.

RESULTS

SP02SP26-ABD shows similar nanomolar affinity for human, mouse and rat PDGFRβ. Cellular uptake and hence subnanomolar cytotoxic potency of auristatinF-conjugated SP02SP26-ABD was observed in PDGFRβ-expressing cell lines. Immunohistochemistry of mouse and human fibrotic livers confirmed co-localization of PDGFRβ with markers of active fibrosis. In all three liver fibrosis models, PET-CT imaging and biodistribution analysis of [89Zr]Zr-SP02SP26-ABD revealed increased PDGFRβ-specific uptake in fibrotic livers. In the DDC model, liver uptake was 12.15 ± 0.45, 15.07 ± 0.90, 20.23 ± 1.34, and 20.93 ± 4.35%ID/g after 1,2,3 and 4 weeks of fibrogenesis, respectively, compared to 7.56 ± 0.85%ID/g in healthy mice. Autoradiography revealed preferential uptake in the fibrotic (PDGFRβ-expressing) periportal areas.

CONCLUSION

The anti-PDGFRβ Fibrobody® SP02SP26-ABD shows selective and high-degree targeting of activated myofibroblasts in liver fibrosis, and qualifies as a vector for diagnostic and therapeutic purposes.

An Integrative Transcriptome Subtraction Strategy to Identify Human lncRNAs That Specifically Play a Role in Activation of Human Hepatic Stellate Cells

Fibrotic liver features excessive deposition of extracellular matrix (ECM), primarily produced from "activated" hepatic stellate cells (HSCs). While targeting human HSCs (hHSCs) in fibrosis therapeutics shows promise, the overall understanding of hHSC activation remains limited, in part because it is very challenging to define the role of human long non-coding RNAs (lncRNAs) in hHSC activation. To address this challenge, we identified another cell type that acts via a diverse gene network to promote fibrogenesis. Then, we identified the lncRNAs that were differentially regulated in activated hHSCs and the other profibrotic cell. Next, we conducted concurrent analysis to identify those lncRNAs that were specifically involved in fibrogenesis. We tested and confirmed that transdifferentiation of vascular smooth muscle cells (VSMCs) represents such a process. By overlapping TGFβ-regulated lncRNAs in multiple sets of hHSCs and VSMCs, we identified a highly selected list of lncRNA candidates that could specifically play a role in hHSC activation. We experimentally characterized one human lncRNA, named CARMN, which was significantly regulated by TGFβ in all conditions above. CARMN knockdown significantly reduced the expression levels of a panel of marker genes for hHSC activation, as well as the levels of ECM deposition and hHSC migration. Conversely, gain of function of CARMN using CRISPR activation (CRISPR-a) yielded the completely opposite effects. Taken together, our work addresses a bottleneck in identifying human lncRNAs that specifically play a role in hHSC activation and provides a framework to effectively select human lncRNAs with significant pathophysiological role.

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.

Proteomic study of gamma-oryzanol preventive effect on a diet-induced non-alcoholic fatty liver disease model

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease associated with obesity and diabetes prevalence. The use of natural compounds has become an attractive approach to prevent NAFLD and its progression. Gamma-oryzanol (Orz) is a natural compound whose beneficial effects on chronic metabolic diseases have been reported. Therefore, we aimed to investigate the preventive effect of Orz on the hepatic proteome in a diet induced NAFLD model. Wistar rats were randomly distributed into three experimental groups (n=6/group) according to the diet received for 30 weeks: Control group, high sugar-fat (HSF) group, and HSF+Orz group. The isolated Orz was added to the chow at the dose of 0.5% (w/w). We evaluated the nutritional profile, characterized the presence of steatosis through histological analysis, triglyceride content in liver tissue and hepatic inflammation. Next, we performed label-free quantitative proteomics of hepatic tissue. Network analysis was performed to describe involved protein pathways. NAFLD induction was characterized by the presence of hepatic steatosis. Orz prevented lipid accumulation. The compound prevented alterations of the hepatic proteome, highlighted by the modulation of lipid metabolism, inflammation, oxidative stress, xenobiotic metabolism, and the sirtuin signaling pathway. It was possible to identify key altered pathways of NAFLD pathophysiology modulated by Orz which may provide insights into NAFLD treatment targets.

Bile acid metabolism and signaling in health and disease: molecular mechanisms and therapeutic targets

Bile acids, once considered mere dietary surfactants, now emerge as critical modulators of macronutrient (lipid, carbohydrate, protein) metabolism and the systemic pro-inflammatory/anti-inflammatory balance. Bile acid metabolism and signaling pathways play a crucial role in protecting against, or if aberrant, inducing cardiometabolic, inflammatory, and neoplastic conditions, strongly influencing health and disease. No curative treatment exists for any bile acid influenced disease, while the most promising and well-developed bile acid therapeutic was recently rejected by the FDA. Here, we provide a bottom-up approach on bile acids, mechanistically explaining their biochemistry, physiology, and pharmacology at canonical and non-canonical receptors. Using this mechanistic model of bile acids, we explain how abnormal bile acid physiology drives disease pathogenesis, emphasizing how ceramide synthesis may serve as a unifying pathogenic feature for cardiometabolic diseases. We provide an in-depth summary on pre-existing bile acid receptor modulators, explain their shortcomings, and propose solutions for how they may be remedied. Lastly, we rationalize novel targets for further translational drug discovery and provide future perspectives. Rather than dismissing bile acid therapeutics due to recent setbacks, we believe that there is immense clinical potential and a high likelihood for the future success of bile acid therapeutics.

Increased hepatoprotective effects of the novel farnesoid X receptor agonist INT-787 versus obeticholic acid in a mouse model of nonalcoholic steatohepatitis

The nuclear farnesoid X receptor (FXR), a master regulator of bile acid and metabolic homeostasis, is a key target for treatment of nonalcoholic steatohepatitis (NASH). This study compared efficacy of FXR agonists obeticholic acid (OCA) and INT-787 by liver histopathology, plasma biomarkers of liver damage, and hepatic gene expression profiles in the Amylin liver NASH (AMLN) diet-induced and biopsy-confirmed Lepob/ob mouse model of NASH. Lepob/ob mice were fed the AMLN diet for 12 weeks before liver biopsy and subsequent treatment with vehicle, OCA, or INT-787 for 8 weeks. Hepatic steatosis, inflammation, and fibrosis (liver lipids, galectin-3, and collagen 1a1 [Col1a1], respectively), as well as plasma alanine transaminase (ALT) and aspartate transaminase (AST) levels, were assessed. Hepatic gene expression was assessed in Lepob/ob mice that were fed the AMLN diet for 14 weeks then treated with vehicle, OCA, or INT-787 for 2 weeks. INT-787, which is equipotent to OCA but more hydrophilic, significantly reduced liver lipids, galectin-3, and Col1a1 compared with vehicle, and to a greater extent than OCA. INT-787 significantly reduced plasma ALT and AST levels, whereas OCA did not. INT-787 modulated a substantially greater number of genes associated with FXR signaling, lipid metabolism, and stellate cell activation relative to OCA in hepatic tissue. These findings demonstrate greater efficacy of INT-787 treatment compared with OCA in improving liver histopathology, decreasing liver enzyme levels, and enhancing gene regulation, suggesting superior clinical potential of INT-787 for the treatment of NASH and other chronic liver diseases.

Phenotypes and ontogeny of senescent hepatic stellate cells in metabolic dysfunction-associated steatohepatitis

BACKGROUND & AIMS

Hepatic stellate cells (HSCs) are the key drivers of fibrosis in metabolic dysfunction-associated steatohepatitis (MASH), the fastest growing cause of hepatocellular carcinoma (HCC) worldwide. HSCs are heterogenous, and a senescent subset of HSCs is implicated in hepatic fibrosis and HCC. Administration of anti-uPAR (urokinase-type plasminogen activator receptor) CAR T cells has been shown to deplete senescent HSCs and attenuate fibrosis in murine models. However, the comprehensive features of senescent HSCs in MASH, as well as their cellular ontogeny have not been characterized; hence, we aimed to comprehensively characterize and define the origin of HSCs in human and murine MASH.

METHODS

To comprehensively characterize the phenotype and ontogeny of senescent HSCs in human and murine MASH, we integrated senescence-associated beta galactosidase activity with immunostaining, flow cytometry and single-nucleus RNA sequencing (snRNAseq). We integrated the immunohistochemical profile with a senescence score applied to snRNAseq data to characterize senescent HSCs and mapped the evolution of uPAR expression in MASH.

RESULTS

Using pseudotime trajectory analysis, we establish that senescent HSCs arise from activated HSCs. While uPAR is expressed in MASH, the magnitude and cell-specificity of its expression evolve with disease stage. In early disease, uPAR is more specific to activated and senescent HSCs, while it is also expressed by myeloid-lineage cells, including Trem2+ macrophages and myeloid-derived suppressor cells, in late disease. Furthermore, we identify novel surface proteins expressed on senescent HSCs in human and murine MASH that could be exploited as therapeutic targets.

CONCLUSIONS

These data define features of HSC senescence in human and murine MASH, establishing an important blueprint to target these cells as part of future antifibrotic therapies.

IMPACT AND IMPLICATIONS

Hepatic stellate cells (HSCs) are the primary drivers of scarring in chronic liver diseases. As injury develops, a subset of HSCs become senescent; these cells are non-proliferative and pro-inflammatory, thereby contributing to worsening liver injury. Here we show that senescent HSCs are expanded in MASH (metabolic dysfunction-associated steatohepatitis) in humans and mice, and we trace their cellular origin from the activated HSC subset. We further characterize expression of uPAR (urokinase plasminogen activated receptor), a protein that marks senescent HSCs, and report that uPAR is also expressed by activated HSCs in early injury, and in immune cells as liver injury advances. We have integrated high-resolution single-nucleus RNA sequencing with immunostaining and flow cytometry to identify five other novel proteins expressed by senescent HSCs, including mannose receptor CD206, which will facilitate future therapeutic development.

Chinese herbal medicines: The modulator of nonalcoholic fatty liver disease targeting oxidative stress

ETHNOPHARMACOLOGICAL RELEVANCE

Plants are a natural treasure trove; their secondary metabolites participate in several pharmacological processes, making them a crucial component in the synthesis of novel pharmaceuticals and serving as a reserve resource foundation in this process. Nonalcoholic fatty liver disease (NAFLD) is associated with the risk of progression to hepatitis and liver cancer. The "Treatise on Febrile Diseases," "Compendium of Materia Medica," and "Thousand Golden Prescriptions" have listed herbal remedies to treat liver diseases.

AIM OF THE REVIEW

Chinese herbal medicines have been widely used for the prevention and treatment of NAFLD owing to their efficacy and low side effects. The production of reactive oxygen species (ROS) during NAFLD, and the impact and potential mechanism of ROS on the pathogenesis of NAFLD are discussed in this review. Furthermore, common foods and herbs that can be used to prevent NAFLD, as well as the structure-activity relationships and potential mechanisms, are discussed.

METHODS

Web of Science, PubMed, CNKI database, Google Scholar, and WanFang database were searched for natural products that have been used to treat or prevent NAFLD in the past five years. The primary search was performed using the following keywords in different combinations in full articles: NAFLD, herb, natural products, medicine, and ROS. More than 400 research papers and review articles were found and analyzed in this review.

RESULTS

By classifying and discussing the literature, we obtained 86 herbaceous plants, 28 of which were derived from food and 58 from Chinese herbal medicines. The mechanism of NAFLD was proposed through experimental studies on thirteen natural compounds (quercetin, hesperidin, rutin, curcumin, resveratrol, epigallocatechin-3-gallate, salvianolic acid B, paeoniflorin, ginsenoside Rg1, ursolic acid, berberine, honokiol, emodin). The occurrence and progression of NAFLD could be prevented by natural antioxidants through several pathways to prevent ROS accumulation and reduce hepatic cell injuries caused by excessive ROS.

CONCLUSION

This review summarizes the natural products and routinely used herbs (prescription) in the prevention and treatment of NAFLD. Firstly, the mechanisms by which natural products improve NAFLD through antioxidant pathways are elucidated. Secondly, the potential of traditional Chinese medicine theory in improving NAFLD is discussed, highlighting the safety of food-medicine homology and the broader clinical potential of multi-component formulations in improving NAFLD. Aiming to provide theoretical basis for the prevention and treatment of NAFLD.

Obeticholic acid-loaded exosomes attenuate liver fibrosis through dual targeting of the FXR signaling pathway and ECM remodeling

End-stage of liver fibrosis as a precancerous state could lead to cirrhosis and hepatocellular carcinoma which liver transplantation is the only effective treatment. Previous studies have indicated that farnesoid X receptor (FXR) agonists, such as obeticholic acid (OCA) protect against hepatic injuries. However, free OCA administration results in side effects in clinical trials that could be alleviated by applying bio carriers such as MSC-derived exosomes (Exo) with the potential to mimic the biological regenerative effect of their parent cells, as proposed in this study. Loading OCA into the Exo was conducted via water bath sonication. Ex vivo bio distribution studies validated the Exo-loaded OCA more permanently accumulated in the liver. Using CCL4-induced liver fibrosis, we proposed whether Exo isolated from human Warton's Jelly mesenchymal stem cells loaded with a minimal dosage of OCA can facilitate liver recovery. Notably, Exo-loaded OCA exerted additive anti-fibrotic efficacy on histopathological features in CCL4-induced fibrotic mice. Compared to baseline, Exo-mediated delivery OCA results in marked improvements in the fibrotic-related indicators as well as serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) concentrations. Accordingly, the synergistic impact of Exo-loaded OCA as a promising approach is associated with the inactivation of hepatic stellate cells (HSCs), extracellular matrix (ECM) remodeling, and Fxr-Cyp7a1 cascade on CCL4-induced liver fibrosis mice. In conclusion, our data confirmed the additive protective effects of Exo-loaded OCA in fibrotic mice, which suggests a valuable therapeutic strategy to combat liver fibrosis. Furthermore, the use of Exo for accurate drug delivery to the liver tissue can be inspiring.

Changes in liver metabolic pathways demonstrate efficacy of the combined dietary and microbial therapeutic intervention in MASLD mouse model

OBJECTIVE

Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as non-alcoholic fatty liver disease (NAFLD), is the most prevalent liver disease globally, yet no therapies are approved. The effects of Escherichia coli Nissle 1917 expressing aldafermin, an engineered analog of the intestinal hormone FGF19, in combination with dietary change were investigated as a potential treatment for MASLD.

METHODS

MASLD was induced in C57BL/6J male mice by American lifestyle-induced obesity syndrome diet and then switched to a standard chow diet for seven weeks. In addition to the dietary change, the intervention group received genetically engineered E. coli Nissle expressing aldafermin, while control groups received either E. coli Nissle vehicle or no treatment. MASLD-related plasma biomarkers were measured using an automated clinical chemistry analyzer. The liver steatosis was assessed by histology and bioimaging analysis using Fiji (ImageJ) software. The effects of the intervention in the liver were also evaluated by RNA sequencing and liquid-chromatography-based non-targeted metabolomics analysis. Pathway enrichment studies were conducted by integrating the differentially expressed genes from the transcriptomics findings with the metabolites from the metabolomics results using Ingenuity pathway analysis.

RESULTS

After the intervention, E. coli Nissle expressing aldafermin along with dietary changes reduced body weight, liver steatosis, plasma aspartate aminotransferase, and plasma cholesterol levels compared to the two control groups. The integration of transcriptomics with non-targeted metabolomics analysis revealed the downregulation of amino acid metabolism and related receptor signaling pathways potentially implicated in the reduction of hepatic steatosis and insulin resistance. Moreover, the downregulation of pathways linked to lipid metabolism and changes in amino acid-related pathways suggested an overall reduction of oxidative stress in the liver.

CONCLUSIONS

These data support the potential for using engineered microbial therapeutics in combination with dietary changes for managing MASLD.

Hepatocyte survival and proliferation by fibroblast growth factor 7 attenuates liver inflammation, and fibrogenesis during acute liver injury via paracrine mechanisms

Hepatocyte damage during liver injury instigates activation of macrophages and hepatic stellate cells (HSCs) resulting in liver inflammation and fibrosis respectively. Improving hepatocyte survival and proliferation thereby ameliorating inflammation and fibrosis represents a promising approach for the treatment of liver injury. In the liver, fibroblast growth factors (FGFs) play a crucial role in promoting hepatocyte proliferation and tissue regeneration. Among 22 FGFs, FGF7 induces hepatocyte survival and liver regeneration as shown previously in mouse models of cholestatic liver injury and partial hepatectomy. We hypothesized that FGF7 promotes hepatocyte survival and proliferation by interacting with FGFR2b, expressed on hepatocytes, and ameliorates liver injury (inflammation and early fibrogenesis) via paracrine mechanisms. To prove this hypothesis and to study the effect of FGF7 on hepatocytes and liver injury, we administered FGF7 exogenously to mice with acute carbon tetrachloride (CCl4)-induced liver injury. We thereafter studied the underlying mechanisms and the effect of exogenous FGF7 on hepatocyte survival and proliferation, and the consequent paracrine effects on macrophage-induced inflammation, and HSCs activation in vitro and in vivo. We observed that the expression of FGF7 as well as FGFR2 is upregulated during acute liver injury. Co-immunostaining of FGF7 and collagen-I confirmed that FGF7 is expressed by HSCs and is possibly captured by the secreted ECM. Immunohistochemical analysis of liver sections showed increased hepatocyte proliferation upon exogenous FGF7 treatment as determined by Ki67 expression. Mechanistically, exogenous FGF7 improved hepatocyte survival (and increased drug detoxification) via AKT and ERK pathways while maintaining hepatocyte quiescence restricting hepatocarcinogenesis via P27 pathways. Flow cytometry analysis revealed that improved hepatocyte survival and proliferation leads to a decrease in infiltrated monocytes-derived macrophages, as a result of reduced CCL2 (and CXCL8) expression by hepatocytes. Moreover, conditioned medium studies showed reduced collagen-I secretion by HSCs (indicative of HSCs activation) upon treatment with FGF7-treated hepatocytes conditioned medium. Altogether, we show that exogenous administration of FGF7 induces hepatocyte survival and proliferation and leads to amelioration of inflammatory response and fibrosis in acute liver injury via paracrine mechanisms. Our study further demonstrates that FGF7, FGF7 derivatives, or nano-engineered FGF7 may benefit patients with hepatic dysfunction.

Resmetirom for nonalcoholic fatty liver disease: a randomized, double-blind, placebo-controlled phase 3 trial

Nonalcoholic steatohepatitis (NASH) is a progressive liver disease with no approved treatment. MAESTRO-NAFLD-1 was a 52-week randomized, double-blind, placebo-controlled phase 3 trial evaluating the safety of resmetirom in adults with nonalcoholic fatty liver disease and presumed NASH. Patients were randomized to three double-blind arms (100 mg resmetirom (n = 325), 80 mg resmetirom (n = 327) or placebo (n = 320)) or open-label 100 mg resmetirom (n = 171). The primary end point was incidence of treatment-emergent adverse events (TEAEs) over 52 weeks and key secondary end points were LDL-C, apoB, triglycerides (over 24 weeks), hepatic fat (over 16 and 52 weeks) and liver stiffness (over 52 weeks). Resmetirom was safe and well tolerated. TEAEs occurred in 86.5% (open-label 100 mg resmetirom), 86.1% (100 mg resmetirom), 88.4% (80 mg resmetirom) and 81.8% (placebo) of patients. TEAEs in excess of placebo included diarrhea and nausea at the initiation of treatment. Key secondary end points included least square means difference from placebo at 80 mg, 100 mg resmetirom: LDL-C (-11.1%, -12.6%), apoB (-15.6%, -18.0%), triglycerides (-15.4%, -20.4%), 16-week hepatic fat (-34.9%, -38.6%), (P < 0.0001) and liver stiffness (-1.02, -1.70) and 52-week hepatic fat (-28.8, -33.9). These findings demonstrate resmetirom was safe and well tolerated in adults with presumed NASH, supporting a role for further clinical development. (ClinicalTrials.gov identifier NCT04197479 ).

Fibroblasts in liver cancer: functions and therapeutic translation

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

Interdisciplinary advances reshape the delivery tools for effective NASH treatment

BACKGROUND

Nonalcoholic steatohepatitis (NASH), a severe systemic and inflammatory subtype of nonalcoholic fatty liver disease, eventually develops into cirrhosis and hepatocellular carcinoma with few options for effective treatment. Currently potent small molecules identified in preclinical studies are confronted with adverse effects and long-term ineffectiveness in clinical trials. Nevertheless, highly specific delivery tools designed from interdisciplinary concepts may address the significant challenges by either effectively increasing the concentrations of drugs in target cell types, or selectively manipulating the gene expression in liver to resolve NASH.

SCOPE OF REVIEW

We focus on dissecting the detailed principles of the latest interdisciplinary advances and concepts that direct the design of future delivery tools to enhance the efficacy. Recent advances have indicated that cell and organelle-specific vehicles, non-coding RNA research (e.g. saRNA, hybrid miRNA) improve the specificity, while small extracellular vesicles and coacervates increase the cellular uptake of therapeutics. Moreover, strategies based on interdisciplinary advances drastically elevate drug loading capacity and delivery efficiency and ameliorate NASH and other liver diseases.

MAJOR CONCLUSIONS

The latest concepts and advances in chemistry, biochemistry and machine learning technology provide the framework and strategies for the design of more effective tools to treat NASH, other pivotal liver diseases and metabolic disorders.

PPAR-γ signaling in nonalcoholic fatty liver disease: Pathogenesis and therapeutic targets

Non-alcoholic fatty liver disease (NAFLD), currently the leading cause of global chronic liver disease, has emerged as a major public health problem, more efficient therapeutics of which are thus urgently needed. Peroxisome proliferator-activated receptor γ (PPAR-γ), ligand-activated transcription factors of the nuclear hormone receptor superfamily, is considered a crucial metabolic regulator of hepatic lipid metabolism and inflammation. The role of PPAR-γ in the pathogenesis of NAFLD is gradually being recognized. Here, we outline the involvement of PPAR-γ in the pathogenesis of NAFLD through adipogenesis, insulin resistance, inflammation, oxidative stress, endoplasmic reticulum stress, and fibrosis. In addition, the evidence for PPAR-γ- targeted therapy for NAFLD are summarized. Altogether, PPAR-γ is a promising therapeutic target for NAFLD, and the development of drugs that can balance the beneficial and undesirable effects of PPAR-γ will bring new light to NAFLD patients.

Assessment of the mode of action underlying development of liver lesions in mice following oral exposure to HFPO-DA and relevance to humans

HFPO-DA (ammonium, 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoate) is a short-chain polyfluorinated alkyl substance (PFAS) used in the manufacture of some types of fluorinated polymers. Like many PFAS, toxicity studies with HFPO-DA indicate the liver is the primary target of toxicity in rodents following oral exposure. Due to the structural diversity of PFAS, the mode of action (MOA) can differ between PFAS for the same target tissue. There is significant evidence for involvement of peroxisome proliferator-activated receptor alpha (PPARα) activation based on molecular and histopathological responses in the liver following HFPO-DA exposure, but other MOAs have also been hypothesized based on limited evidence. The MOA underlying the liver effects in mice exposed to HFPO-DA was assessed in the context of the Key Events (KEs) outlined in the MOA framework for PPARα activator-induced rodent hepatocarcinogenesis. The first 3 KEs (ie, PPARα activation, alteration of cell growth pathways, and perturbation of cell growth/survival) are supported by several lines of evidence from both in vitro and in vivo data available for HFPO-DA. In contrast, alternate MOAs, including cytotoxicity, PPARγ and mitochondrial dysfunction are generally not supported by the scientific literature. HFPO-DA-mediated liver effects in mice are not expected in humans as only KE 1, PPARα activation, is shared across species. PPARα-mediated gene expression in humans produces only a subset (ie, lipid modulating effects) of the responses observed in rodents. As such, the adverse effects observed in rodent livers should not be used as the basis of toxicity values for HFPO-DA for purposes of human health risk assessment.

Ferroptosis in non-alcoholic liver disease: Molecular mechanisms and therapeutic implications

Ferroptosis refers to a novel modality of regulated cell death characterized by excessive iron accumulation and overwhelming lipid peroxidation, which takes an important part in multiple pathological processes associated with cell death. Considering the crucial roles of the liver in iron and lipid metabolism and its predisposition to oxidative insults, more and more studies have been conducted to explore the relationship between ferroptosis and various liver disorders, including non-alcoholic fatty liver disease (NAFLD). With increased morbidity and high mortality rates, NAFLD has currently emerged as a global public health issue. However, the etiology of NAFLD is not fully understood. In recent years, an accumulating body of evidence have suggested that ferroptosis plays a pivotal role in the pathogenesis of NAFLD, but the precise mechanisms underlying how ferroptosis affects NAFLD still remain obscure. Here, we summarize the molecular mechanisms of ferroptosis and its complicated regulation systems, delineate the different effects that ferroptosis exerts in different stages of NAFLD, and discuss some potential effective therapies targeting ferroptosis for NAFLD treatment, which putatively points out a novel direction for NAFLD treatment.

Hepatic Stellate Cells: Dictating Outcome in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a fast growing, chronic liver disease affecting ∼25% of the global population. Nonalcoholic fatty liver disease severity ranges from the less severe simple hepatic steatosis to the more advanced nonalcoholic steatohepatitis (NASH). The presence of NASH predisposes individuals to liver fibrosis, which can further progress to cirrhosis and hepatocellular carcinoma. This makes hepatic fibrosis an important indicator of clinical outcomes in patients with NASH. Hepatic stellate cell activation dictates fibrosis development during NASH. Here, we discuss recent advances in the analysis of the profibrogenic pathways and mediators of hepatic stellate cell activation and inactivation, which ultimately determine the course of disease in nonalcoholic fatty liver disease/NASH.

Prenatal Choline Supplement in a Maternal Obesity Model Modulates Offspring Hepatic Lipidomes

Maternal obesity during pregnancy adversely impacts offspring health, predisposing them to chronic metabolic diseases characterized by insulin resistance, dysregulated macronutrient metabolism, and lipid overload, such as metabolic-associated fatty liver disease (MAFLD). Choline is a semi-essential nutrient involved in lipid and one-carbon metabolism that is compromised during MAFLD progression. Here, we investigated under high-fat (HF) obesogenic feeding how maternal choline supplementation (CS) influenced the hepatic lipidome of mouse offspring. Our results demonstrate that maternal HF+CS increased relative abundance of a subclass of phospholipids called plasmalogens in the offspring liver at both embryonic day 17.5 and after 6 weeks of postnatal HF feeding. Consistent with the role of plasmalogens as sacrificial antioxidants, HF+CS embryos were presumably protected with lower oxidative stress. After postnatal HF feeding, the maternal HF+CS male offspring also had higher relative abundance of both sphingomyelin d42:2 and its side chain, nervonic acid (FA 24:1). Nervonic acid is exclusively metabolized in the peroxisome and is tied to plasmalogen synthesis. Altogether, this study demonstrates that under the influence of obesogenic diet, maternal CS modulates the fetal and postnatal hepatic lipidome of male offspring, favoring plasmalogen synthesis, an antioxidative response that may protect the mouse liver from damages due to HF feeding.

4-Methylumbelliferone Targets Revealed by Public Data Analysis and Liver Transcriptome Sequencing

4-methylumbelliferone (4MU) is a well-known hyaluronic acid synthesis inhibitor and an approved drug for the treatment of cholestasis. In animal models, 4MU decreases inflammation, reduces fibrosis, and lowers body weight, serum cholesterol, and insulin resistance. It also inhibits tumor progression and metastasis. The broad spectrum of effects suggests multiple and yet unknown targets of 4MU. Aiming at 4MU target deconvolution, we have analyzed publicly available data bases, including: 1. Small molecule library Bio Assay screening (PubChemBioAssay); 2. GO pathway databases screening; 3. Protein Atlas Database. We also performed comparative liver transcriptome analysis of mice on normal diet and mice fed with 4MU for two weeks. Potential targets of 4MU public data base analysis fall into two big groups, enzymes and transcription factors (TFs), including 13 members of the nuclear receptor superfamily regulating lipid and carbohydrate metabolism. Transcriptome analysis revealed changes in the expression of genes involved in bile acid metabolism, gluconeogenesis, and immune response. It was found that 4MU feeding decreased the accumulation of the glycogen granules in the liver. Thus, 4MU has multiple targets and can regulate cell metabolism by modulating signaling via nuclear receptors.

Oxy210, a Semi-Synthetic Oxysterol, Inhibits Profibrotic Signaling in Cellular Models of Lung and Kidney Fibrosis

Oxy210, a semi-synthetic oxysterol derivative, displays cell-selective inhibition of Hedgehog (Hh) and transforming growth factor beta (TGF-β) signaling in epithelial cells, fibroblasts, and macrophages as well as antifibrotic and anti-inflammatory efficacy in models of liver fibrosis. In the present report, we examine the effects of Oxy210 in cellular models of lung and kidney fibrosis, such as human lung fibroblast cell lines IMR-90, derived from healthy lung tissue, and LL97A, derived from an idiopathic pulmonary fibrosis (IPF) patient. In addition, we examine the effects of Oxy210 in primary human renal fibroblasts, pericytes, mesangial cells, and renal tubular epithelial cells, known for their involvement in chronic kidney disease (CKD) and kidney fibrosis. We demonstrate in fibroblasts that the expression of several profibrotic TGF-β target genes, including fibronectin (FN), collagen 1A1 (COL1A1), and connective tissue growth factor (CTGF) are inhibited by Oxy210, both at the basal level and following TGF-β stimulation in a statistically significant manner. The inhibition of COL1A1 gene expression translated directly to significantly reduced COL1A1 protein expression. In human primary small airway epithelial cells (HSAECs) and renal tubular epithelial cells, Oxy210 significantly inhibited TGF-β target gene expression associated with epithelial-mesenchymal transition (EMT). Oxy210 also inhibited the proliferation of fibroblasts, pericytes, and mesangial cells in a dose-dependent and statistically significant manner.

Assessment of Mouse Liver Histopathology Following Exposure to HFPO-DA With Emphasis on Understanding Mechanisms of Hepatocellular Death

Ammonium 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-propanoate (HFPO-DA) is a short chain member of per- and polyfluoroalkyl substances (PFAS). To better understand the relevance of histopathological effects seen in livers of mice exposed to HFPO-DA for human health risk assessment, histopathological effects were summarized from hematoxylin and eosin (H&E)-stained sections in several repeat-dose toxicity studies in mice. Findings across studies revealed histopathological changes consistent with peroxisomal proliferation, whereas two reports of steatosis could not be confirmed in the published figures. In addition, mechanisms of hepatocellular death were assessed in H&E sections as well as with the apoptotic marker cleaved caspase-3 (CCasp3) in newly cut sections from archived liver blocks from select studies. A comparison of serially CCasp3 immunolabeled and H&E-stained sections revealed that mechanisms of hepatocellular death cannot be clearly discerned in H&E-stained liver sections alone as several examples of putatively necrotic cells were positive for CCasp3. Published whole genome transcriptomic data were also reevaluated for enrichment of various forms of hepatocellular death in response to HFPO-DA, which revealed enrichment of apoptosis and autophagy, but not ferroptosis, pyroptosis, or necroptosis. These morphological and molecular findings are consistent with transcriptomic evidence for peroxisome proliferator-activated receptor alpha (PPARα) signaling in HFPO-DA exposed mice.

Formulating elafibranor and obeticholic acid with phospholipids decreases drug-induced association of SPARC to extracellular vesicles from LX-2 human hepatic stellate cells

Chronic hepatic diseases often compromise liver function and are directly responsible for up to two million yearly deaths world-wide. There are yet no treatment options to solve this global medical need. Experimental drugs elafibranor (Ela) and obeticholic acid (OA) appeared promising in numerous earlier studies, but they recently struggled to show significant benefits in patients. Little is known on the drugs' impact on hepatic stellate cells (HSCs), key players in liver fibrogenesis. We recently reported a beneficial effect of polyenylphosphatidylcholines (PPCs)-rich formulations in reverting fibrogenic features of HSCs, including differences in their extracellular vesicles (EVs). Here, we newly formulated Ela and OA in PPC liposomes and evaluated their performance on the LX-2 (human HSC) cell line through our rigorous methods of EV-analysis, now expanded to include lipidomics. We show that direct treatments with Ela and OA increase EV-associated secreted protein acidic and cysteine rich (SPARC), a matricellular protein overexpressed in fibrogenesis. However, our results suggest that this potentially damaging drugs' action to HSCs could be mitigated when delivering them with lipid-based formulations, most notably with a PPC-rich phospholipid inducing specific changes in the cellular and EV phospholipid composition. Thus, EV analysis substantially deepens evaluations of drug performances and delivery strategies.

Activated Hepatic Stellate Cells in Hepatocellular Carcinoma: Their Role as a Potential Target for Future Therapies

Hepatocellular carcinoma (HCC) is a global healthcare challenge, which affects more than 815,000 new cases every year. Activated hepatic stellate cells (aHSCs) remain the principal cells that drive HCC onset and growth. aHSCs suppress the anti-tumor immune response through interaction with different immune cells. They also increase the deposition of the extracellular matrix proteins, challenging the reversion of fibrosis and increasing HCC growth and metastasis. Therapy for HCC was reported to activate HSCs, which could explain the low efficacy of current treatments. Conversely, recent studies aimed at the deactivation of HSCs show that they have been able to inhibit HCC growth. In this review article, we discuss the role of aHSCs in HCC pathophysiology and therapy. Finally, we provide suggestions for the experimental implementation of HSCs in HCC therapies.

Utility of Human Relevant Preclinical Animal Models in Navigating NAFLD to MAFLD Paradigm

Fatty liver disease is an emerging contributor to disease burden worldwide. The past decades of work established the heterogeneous nature of non-alcoholic fatty liver disease (NAFLD) etiology and systemic contributions to the pathogenesis of the disease. This called for the proposal of a redefinition in 2020 to that of metabolic dysfunction-associated fatty liver disease (MAFLD) to better reflect the current understanding of the disease. To date, several clinical cohort studies comparing NAFLD and MAFLD hint at the relevancy of the new nomenclature in enriching for patients with more severe hepatic injury and extrahepatic comorbidities. However, the underlying systemic pathogenesis is still not fully understood. Preclinical animal models have been imperative in elucidating key biological mechanisms in various contexts, including intrahepatic disease progression, interorgan crosstalk and systemic dysregulation. Furthermore, they are integral in developing novel therapeutics against MAFLD. However, substantial contextual variabilities exist across different models due to the lack of standardization in several aspects. As such, it is crucial to understand the strengths and weaknesses of existing models to better align them to the human condition. In this review, we consolidate the implications arising from the change in nomenclature and summarize MAFLD pathogenesis. Subsequently, we provide an updated evaluation of existing MAFLD preclinical models in alignment with the new definitions and perspectives to improve their translational relevance.

Enhanced Expression of ARK5 in Hepatic Stellate Cell and Hepatocyte Synergistically Promote Liver Fibrosis

AMPK-related protein kinase 5 (ARK5) is involved in a broad spectrum of physiological and cell events, and aberrant expression of ARK5 has been observed in a wide variety of solid tumors, including liver cancer. However, the role of ARK5 in liver fibrosis remains largely unexplored. We found that ARK5 expression was elevated in mouse fibrotic livers, and showed a positive correlation with the progression of liver fibrosis. ARK5 was highly expressed not only in activated hepatic stellate cells (HSCs), but also in hepatocytes. In HSCs, ARK5 prevents the degradation of transforming growth factor β type I receptor (TβRI) and mothers against decapentaplegic homolog 4 (Smad4) proteins by inhibiting the expression of Smad ubiquitin regulatory factor 2 (Smurf2), thus maintaining the continuous transduction of the transforming growth factor β (TGF-β) signaling pathway, which is essential for cell activation, proliferation and survival. In hepatocytes, ARK5 induces the occurrence of epithelial-mesenchymal transition (EMT), and also promotes the secretion of inflammatory factors. Inflammatory factors, in turn, further enhance the activation of HSCs and deepen the degree of liver fibrosis. Notably, we demonstrated in a mouse model that targeting ARK5 with the selective inhibitor HTH-01-015 attenuates CCl₄-induced liver fibrosis in mice. Taken together, the results indicate that ARK5 is a critical driver of liver fibrosis, and promotes liver fibrosis by synergy between HSCs and hepatocytes.

Roles of hepatic stellate cells in NAFLD: From the perspective of inflammation and fibrosis

Non-alcoholic fatty liver disease (NAFLD) has become one of the most common diseases and severe problems worldwide because of the global increase in obesity, dyslipidemia, hypertension, and type 2 diabetes mellitus. NAFLD includes a wide spectrum of liver diseases, the histological forms of which range from non-alcoholic fatty liver (NAFL), which is generally nonprogressive, to non-alcoholic steatohepatitis (NASH), which can progress to chronic hepatitis, liver cirrhosis (LC), and sometimes hepatocellular carcinoma (HCC). Unlike NAFL, as the progressive form of NAFLD, NASH is characterized by the presence of inflammation with or without fibrosis in addition to hepatic steatosis. Although it is widely known and proved that persistent hepatic injury and chronic inflammation in the liver activate quiescent hepatic stellate cells (HSCs) and lead to hepatic fibrosis, the three-step process of “inflammation-fibrosis-carcinoma” in NAFLD has not been investigated and clarified clearly. In this process, the initiation of inflammation in the liver and the function of various liver inflammatory cells have been discussed regularly, while the activated HSCs, which constitute the principal cells responsible for fibrosis and their cross-talk with inflammation, seem not to be investigated specifically and frequently. Also, accumulated evidence suggests that HSCs can not only be activated by inflammation but also participate in the regulation of liver inflammation. Therefore, it is necessary to investigate the unique roles of HSCs in NAFLD from the perspective of inflammation and fibrosis. Here, we review the pivotal effects and mechanisms of HSCs and highlight the potential value of HSC-targeted treatment methods in NAFLD.

Pathogenesis from Inflammation to Cancer in NASH-Derived HCC

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and one of the deadliest cancers worldwide. As opposed to the majority of patients with HCC, approximately 20–30% of cases of non-alcoholic steatohepatitis (NASH)-derived HCC develop malignant tumours in the absence of liver cirrhosis. NASH is characterized by metabolic dysregulation, chronic inflammation and cell death in the liver, which provide a favorable setting for the transformation of inflammation into cancer. This review aims to describe the pathogenesis and the underlying mechanism of the transition from inflammation to cancer in NASH.

A boronate-based modular assembly nanosystem to block the undesirable crosstalk between hepatic stellate cells and Kupffer cells

Crosstalk between Kupffer cells (KCs) and hepatic stellate cells (HSCs) plays an important role in multiple liver disease conditions, including the formation of liver fibrosis in alcohol-associated liver disease (AALD). Therapeutic targeting of the KC-HSC crosstalk is a prime target for therapeutic interventions. Herein, a novel modular nanosystem was designed and prepared through the self-assembly utilizing boric acid and catechol interactions to prepare polymers modified with a CXCR4-inhibiting moieties. The polymers were used to encapsulate anti-miR-155 and to block the undesirable crosstalk between HSCs and KCs by downregulating miR-155 expression in KCs with the parallel inhibition of CXCR4 signaling in activated HSCs. The combined inhibition of miR-155 and CXCR4 at two different liver cell types achieved improved antifibrosis effects in a mouse model of AALD fibrosis. Our finding highlights the key role that blocking the undesirable crosstalk between HSCs and KCs plays in reversing AALD fibrosis as well as demonstrates a proof-of-concept approach for designing and constructing multifunctional delivery nanosystems using orthogonal functional modules based on the understanding of disease mechanisms.

Modulation of hepatic stellate cells by Mutaflor® probiotic in non-alcoholic fatty liver disease management

BACKGROUND

NAFLD and NASH are emerging as primary causes of chronic liver disease, indicating a need for an effective treatment. Mutaflor® probiotic, a microbial treatment of interest, was effective in sustaining remission in ulcerative colitis patients.

OBJECTIVE

To construct a genetic-epigenetic network linked to HSC signaling as a modulator of NAFLD/NASH pathogenesis, then assess the effects of Mutaflor^® on this network.

METHODS

First, in silico analysis was used to construct a genetic-epigenetic network linked to HSC signaling. Second, an investigation using rats, including HFHSD induced NASH and Mutaflor^® treated animals, was designed. Experimental procedures included biochemical and histopathologic analysis of rat blood and liver samples. At the molecular level, the expression of genetic (FOXA2, TEAD2, and LATS2 mRNAs) and epigenetic (miR-650, RPARP AS-1 LncRNA) network was measured by real-time PCR. PCR results were validated with immunohistochemistry (α-SMA and LATS2). Target effector proteins, IL-6 and TGF-β, were estimated by ELISA.

RESULTS

Mutaflor^® administration minimized biochemical and histopathologic alterations caused by NAFLD/NASH. HSC activation and expression of profibrogenic IL-6 and TGF-β effector proteins were reduced via inhibition of hedgehog and hippo pathways. Pathways may have been inhibited through upregulation of RPARP AS-1 LncRNA which in turn downregulated the expression of miR-650, FOXA2 mRNA and TEAD2 mRNA and upregulated LATS2 mRNA expression.

CONCLUSION

Mutaflor^® may slow the progression of NAFLD/NASH by modulating a genetic-epigenetic network linked to HSC signaling. The probiotic may be a useful modality for the prevention and treatment of NAFLD/NASH.

M2 macrophage-derived exosomal microRNA-411-5p impedes the activation of hepatic stellate cells by targeting CAMSAP1 in NASH model

Liver fibrosis is a severe stage of nonalcoholic fatty liver disease (NAFLD), which is closely associated with the activation of hepatic stellate cells (HSCs) and their interaction with macrophages. Exosomes can mediate crosstalk between macrophages and HSCs in NAFLD-associated fibrosis. We found that M2 macrophage-derived exosomes significantly inhibit HSCs activation. RNA-seq studies revealed that miRNA-411-5p was decreased in serum exosomes of nonalcoholic steatohepatitis (NASH) patients as compared with that in healthy controls. Besides, miR-411-5p and M2 macrophage markers are decreased in the liver of the NASH model. We further proved that exosomal miR-411-5p from M2 macrophages inhibit HSCs activation and miR-411-5p directly downregulated the expression of Calmodulin-Regulated Spectrin-Associated Protein 1 (CAMSAP1) to inactivate stellate cells. Importantly, knockdown of CAMSAP1 also inhibited HSCs activation. This study contributes to understanding the underlying mechanism of HSCs activation and indicates CAMSAP1 may serve as a potential therapeutic target for NASH.

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M2 macrophage markers are decreased in the HFHCD-induced rat model of NASH

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M2 macrophage-derived exosomes inhibit HSCs activation via miR-411-5p

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CAMSAP1 is a direct target of miR-411-5p

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Knockdown of CAMSAP1 inhibits HSCs activation

Tanshinone IIA regulates the TGF‑β1/Smad signaling pathway to ameliorate non‑alcoholic steatohepatitis‑related fibrosis

Tanshinone IIA (TIIA) is a major component extracted from the traditional herbal medicine Salvia miltiorrhiza and has been indicated to play a role in the treatment of organ fibrosis. However, the evidence supporting its antifibrotic effect is insufficient and the underlying mechanism is unclear. To investigate the therapeutic effect of TIIA on non-alcoholic steatohepatitis-related fibrosis (NASH-F), the present study used a methionine choline deficiency diet to induce NASH-F in rats, and explored the effect of TIIA on the transforming growth factor-β1 (TGF-β1)/Smad signaling pathway. Wistar rats were randomly divided into control, NASH-F and TIIA groups. After 8 weeks of treatment, the levels of serum markers associated with liver function and fibrosis were measured, liver fat vacuoles and inflammation were assessed by haematoxylin and eosin staining, and liver fibrosis was assessed by Masson's trichrome staining. TGF-β1, Smad2, Smad3, Smad7 and α-smooth muscle actin (α-SMA) mRNA expression, and TGF-β1, Smad2/3, phosphorylated (p)-Smad2/3, Smad7 and α-SMA protein levels were determined. The results revealed that TIIA could remarkably ameliorate liver fat vacuoles and inflammation in NASH-F rats, and could decrease the levels of serum aspartate aminotransferase, alanine aminotransferase, total bilirubin, total bile acid, hyaluronic acid, type Ⅳ collagen, laminin and type III collagen, while increasing the levels of total cholesterol and triglycerides; however, this was not statistically significance. TIIA markedly suppressed the increased TGF-β1, Smad2, Smad3 and α-SMA mRNA expression levels observed in the liver of NASH-F rats, while it increased the mRNA expression level of Smad7. Similarly, TIIA suppressed the increased TGF-β1, p-Smad2/3 and α-SMA protein levels observed in the liver of NASH-F rats, while it increased the protein expression level of Smad7 in vitro and in vivo. TIIA had no significant cytotoxic effect at 10, 20, 40 and 80 µmol/l on human LX-2 cell. In conclusion, the findings of the present study indicated that TIIA alleviated NASH-F by regulating the TGF-β1/Smad signaling pathway. TIIA may be a useful tool in the prevention and treatment of NASH-F.

Moringa oleifera Prevents In vivo Carbon Tetrachloride-Induced Liver Fibrosis through Targeting Hepatic Stellate Cells

BACKGROUND: Moringa oleifera (MO) exhibits hepatoprotective properties and provides an anti-liver fibrosis effect. However, its mechanism related to the anti-liver fibrosis effect was still unclear. AIM: The objective of this study was to explain the mechanism of liver fibrosis prevention by MO through hepatic stellate cells (HSCs). MATERIALS AND METHODS: The liver fibrosis model was induced by the intraperitoneal injection of 10% CCl4 twice a week at a one cc/kg BW dose for 12 weeks and followed by a quantity of 2 cc/kg BW for the past 2 weeks. Ethanol extract of MO leaves (150, 300, and 600 mg/kg) was orally administered daily. Double immunofluorescence staining and terminal deoxynucleotidyl transferase dUTP nick end labeling analysis were applied to analyze the markers involved in HSCs activation and a-HSC apoptosis. RESULTS: The results showed that the administration of MO could reduce transforming growth factor-β and nuclear factor-kappa B (NFκB), increase the expression of tumor necrosis factor-related apoptosis-inducing ligand-receptor 2 and caspase-3, and increase the number of apoptosis a-HSCs. CONCLUSION: This study showed that the ethanol extract of MO leaves could inhibit liver fibrosis by inhibiting HSCs activation and inducing of a-HSCs apoptosis through the extrinsic pathway.

Genome-wide CRISPR Screening to Identify Drivers of TGF-β-Induced Liver Fibrosis in Human Hepatic Stellate Cells

Liver fibrosis progression in chronic liver disease leads to cirrhosis, liver failure, or hepatocellular carcinoma and often ends in liver transplantation. Even with an increased understanding of liver fibrogenesis and many attempts to generate therapeutics specifically targeting fibrosis, there is no approved treatment for liver fibrosis. To further understand and characterize the driving mechanisms of liver fibrosis, we developed a high-throughput genome-wide CRISPR/Cas9 screening platform to identify hepatic stellate cell (HSC)-derived mediators of transforming growth factor (TGF)-β-induced liver fibrosis. The functional genomics phenotypic screening platform described here revealed the novel biology of TGF-β-induced fibrogenesis and potential drug targets for liver fibrosis.

Hepatic stellate cells in physiology and pathology

Hepatic stellate cells (HSCs) comprise a minor cell population in the liver but serve numerous critical functions in the normal liver and in response to injury. HSCs are primarily known for their activation upon liver injury and for producing the collagen-rich extracellular matrix in liver fibrosis. In the absence of liver injury, HSCs reside in a quiescent state, in which their main function appears to be the storage of retinoids or vitamin A-containing metabolites. Less appreciated functions of HSCs include amplifying the hepatic inflammatory response and expressing growth factors that are critical for liver development and both the initiation and termination of liver regeneration. Recent single-cell RNA sequencing studies have corroborated earlier studies indictaing that HSC activation involves a diverse array of phenotypic alterations and identified unique HSC populations. This review serves to highlight these many functions of HSCs, and to briefly describe the recent genetic tools that will help to thoroughly investigate the role of HSCs in hepatic physiology and pathology.

SGLT-2 Inhibitors in NAFLD: Expanding Their Role beyond Diabetes and Cardioprotection

Non-alcoholic fatty liver disease (NAFLD) is an ‘umbrella’ term, comprising a spectrum ranging from benign, liver steatosis to non-alcoholic steatohepatitis, liver fibrosis and eventually cirrhosis and hepatocellular carcinoma. NAFLD has evolved as a major health problem in recent years. Discovering ways to prevent or delay the progression of NAFLD has become a global focus. Lifestyle modifications remain the cornerstone of NAFLD treatment, even though various pharmaceutical interventions are currently under clinical trial. Among them, sodium-glucose co-transporter type-2 inhibitors (SGLT-2i) are emerging as promising agents. Processes regulated by SGLT-2i, such as endoplasmic reticulum (ER) and oxidative stress, low-grade inflammation, autophagy and apoptosis are all implicated in NAFLD pathogenesis. In this review, we summarize the current understanding of the NAFLD pathophysiology, and specifically focus on the potential impact of SGLT-2i in NAFLD development and progression, providing current evidence from in vitro, animal and human studies. Given this evidence, further mechanistic studies would advance our understanding of the exact mechanisms underlying the pathogenesis of NAFLD and the potential beneficial actions of SGLT-2i in the context of NAFLD treatment.

The Neglected Role of Bile Duct Epithelial Cells in NASH

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent liver disease worldwide, and affects 25% of the population in Western countries. NAFLD is the hepatic manifestation of the metabolic syndrome, linked to insulin resistance, which is the common pathogenetic mechanism. In approximately 40% of NAFLD patients, steatosis is associated with necro-inflammation and fibrosis, resulting in nonalcoholic steatohepatitis (NASH), a severe condition that may progress to cirrhosis and liver cancer. Although the hepatocyte represents the main target of the disease, involvement of the bile ducts occurs in a subset of patients with NASH, and is characterized by ductular reaction and activation of the progenitor cell compartment, which incites portal fibrosis and disease progression. We aim to dissect the multiple biological effects that adipokines and metabolic alterations exert on cholangiocytes to derive novel information on the mechanisms driven by insulin resistance, which promote fibro-inflammation and carcinogenesis in NASH.

Nanchangmycin regulates FYN, PTK2, and MAPK1/3 to control the fibrotic activity of human hepatic stellate cells

Chronic liver injury causes fibrosis, characterized by the formation of scar tissue resulting from excessive accumulation of extracellular matrix (ECM) proteins. Hepatic stellate cell (HSC) myofibroblasts are the primary cell type responsible for liver fibrosis, yet there are currently no therapies directed at inhibiting the activity of HSC myofibroblasts. To search for potential anti-fibrotic compounds, we performed a high-throughput compound screen in primary human HSC myofibroblasts and identified 19 small molecules that induce HSC inactivation, including the polyether ionophore nanchangmycin (NCMC). NCMC induces lipid re-accumulation while reducing collagen expression, deposition of collagen in the extracellular matrix, cell proliferation, and migration. We find that NCMC increases cytosolic Ca²⁺ and reduces the phosphorylated protein levels of FYN, PTK2 (FAK), MAPK1/3 (ERK2/1), HSPB1 (HSP27), and STAT5B. Further, depletion of each of these kinases suppress COL1A1 expression. These studies reveal a signaling network triggered by NCMC to inactivate HSC myofibroblasts and reduce expression of proteins that compose the fibrotic scar. Identification of the antifibrotic effects of NCMC and the elucidation of pathways by which NCMC inhibits fibrosis provide new tools and therapeutic targets that could potentially be utilized to combat the development and progression of liver fibrosis.

Metabolic Reprogramming of Liver Fibrosis

Liver fibrosis is an excessive and imbalanced deposition of fibrous extracellular matrix (ECM) that is associated with the hepatic wound-healing response. It is also the common mechanism that contributes to the impairment of the liver function that is observed in many chronic liver diseases (CLD). Despite the efforts, no effective therapy against fibrosis exists yet. Worryingly, due to the growing obesity pandemic, fibrosis incidence is on the rise. Here, we aim to summarize the main components and mechanisms involved in the progression of liver fibrosis, with special focus on the metabolic regulation of key effectors of fibrogenesis, hepatic stellate cells (HSCs), and their role in the disease progression. Hepatic cells that undergo metabolic reprogramming require a tightly controlled, fine-tuned cellular response, allowing them to meet their energetic demands without affecting cellular integrity. Here, we aim to discuss the role of ribonucleic acid (RNA)-binding proteins (RBPs), whose dynamic nature being context- and stimuli-dependent make them very suitable for the fibrotic situation. Thus, we will not only summarize the up-to-date literature on the metabolic regulation of HSCs in liver fibrosis, but also on the RBP-dependent post-transcriptional regulation of this metabolic switch that results in such important consequences for the progression of fibrosis and CLD.

Dual role of neutrophils in modulating liver injury and fibrosis during development and resolution of diet-induced murine steatohepatitis

Inflammatory changes in the liver represent a key feature of non-alcoholic steatohepatitis (NASH), the progressive form of non-alcoholic fatty liver disease (NAFLD). Innate immune activation including hepatic neutrophilic infiltration acts as an important inflammatory trigger as well as a potential mediator of inflammation resolution. In this study, we dissected the effects of neutrophil depletion via anti-lymphocyte antigen 6 complex locus G6D (Ly6G) antibodies administration during ongoing high fat-fructose-cholesterol (FFC) diet-induced murine NASH and during inflammation resolution by switching into a low-fat control diet. During NASH progression, protective effects were shown as HSC activation, cell infiltration and activation of pro-inflammatory macrophages were ameliorated. Furthermore, these changes were contrasted with the effects observed when neutrophil depletion was performed during the resolution phase. Impaired resolving mechanisms, such as a failure to balance the pro and anti-inflammatory cytokines ratio, deficient macrophage phenotypic switch into a pro-restorative profile, and defective repair and remodeling processes were observed when neutrophils were depleted in this scenario. This study described phase-dependent contrasting roles of neutrophils as triggers and pro-resolutive mediators of liver injury and fibrosis associated with diet-induced NASH in mice. These findings have important translational implications at the time of designing NASH therapeutic strategies.

Inflammatory and Non-Inflammatory Mechanisms Controlling Cirrhosis Development

Simple Summary

The liver is continuously exposed to several harmful factors, subsequently activating sophisticated mechanisms set-up in order to repair and regenerate the damaged liver and hence to prevent its failure. When the injury becomes chronic, the regenerative response becomes perpetual and goes awry, leading to cirrhosis with a fatal liver dysfunction. Cirrhosis is a well-known risk factor for hepatocellular carcinoma (HCC), the most common, usually lethal, human primary liver neoplasm with very limited therapeutic options. Considering the pivotal role of immune factors in the development of cirrhosis, here we review and discuss the inflammatory pathways and components implicated in the development of cirrhosis. A better understanding of these circuits would help the design of novel strategies to prevent and treat cirrhosis and HCC, two lethal diseases.

Abstract

Because the liver is considered to be one of the most important metabolic organs in the body, it is continuously exposed to damaging environmental agents. Upon damage, several complex cellular and molecular mechanisms in charge of liver recovery and regeneration are activated to prevent the failure of the organ. When liver injury becomes chronic, the regenerative response goes awry and impairs the liver function, consequently leading to cirrhosis, a liver disorder that can cause patient death. Cirrhosis has a disrupted liver architecture and zonation, along with the presence of fibrosis and parenchymal nodules, known as regenerative nodules (RNs). Inflammatory cues contribute to the cirrhotic process in response to chronic damaging agents. Cirrhosis can progress to HCC, the most common and one of the most lethal liver cancers with unmet medical needs. Considering the essential role of inflammatory pathways in the development of cirrhosis, further understanding of the relationship between immune cells and the activation of RNs and fibrosis would guide the design of innovative therapeutic strategies to ameliorate the survival of cirrhotic and HCC patients. In this review, we will summarize the inflammatory mechanisms implicated in the development of cirrhosis.

Rho-Kinase as a Therapeutic Target for Nonalcoholic Fatty Liver Diseases

Nonalcoholic fatty liver disease (NAFLD) is a major public health problem and the most common form of chronic liver disease, affecting 25% of the global population. Although NAFLD is closely linked with obesity, insulin resistance, and type 2 diabetes mellitus, knowledge on its pathogenesis remains incomplete. Emerging data have underscored the importance of Rho-kinase (Rho-associated coiled-coil-containing kinase [ROCK]) action in the maintenance of normal hepatic lipid homeostasis. In particular, pharmacological blockade of ROCK in hepatocytes or hepatic stellate cells prevents the progression of liver diseases such as NAFLD and fibrosis. Moreover, mice lacking hepatic ROCK1 are protected against obesity-induced fatty liver diseases by suppressing hepatic de novo lipogenesis. Here we review the roles of ROCK as an indispensable regulator of obesity-induced fatty liver disease and highlight the key cellular pathway governing hepatic lipid accumulation, with focus on de novo lipogenesis and its impact on therapeutic potential. Consequently, a comprehensive understanding of the metabolic milieu linking to liver dysfunction triggered by ROCK activation may help identify new targets for treating fatty liver diseases such as NAFLD.

Pirfenidone modifies hepatic miRNAs expression in a model of MAFLD/NASH

miRNAs are involved in the development of metabolic associated fatty liver disease (MAFLD) and nonalcoholic steatohepatitis (NASH). We aimed to evaluate modifications by prolonged-release pirfenidone (PR-PFD) on key hepatic miRNAs expression in a MAFLD/NASH model. First, male C57BL/6J mice were randomly assigned into groups and fed with conventional diet (CVD) or high fat and carbohydrate diet (HFD) for 16 weeks. At the end of the eighth week, HFD mice were divided in two and only one half was treated with 300 mg/kg/day of PR-PFD mixed with food. Hepatic expression of miRNAs and target genes that participate in inflammation and lipid metabolism was determined by qRT-PCR and transcriptome by microarrays. Increased hepatic expression of miR-21a-5p, miR-34a-5p, miR-122-5p and miR-103-3p in MAFLD/NASH animals was reduced with PR-PFD. Transcriptome analysis showed that 52 genes involved in lipid and collagen biosynthesis and inflammatory response were downregulated in PR-PFD group. The expression of Il1b, Tnfa, Il6, Tgfb1, Col1a1, and Srebf1 were decreased in PR-PFD treated animals. MAFLD/NASH animals compared to CVD group showed modifications in gene metabolic pathways implicated in lipid metabolic process, inflammatory response and insulin resistance; PR-PFD reversed these modifications.