Hepatic macrophages but not dendritic cells contribute to liver fibrosis by promoting the survival of activated hepatic stellate cells in mice

Liver sinusoidal endothelial cells in hepatic fibrosis: opportunities for future strategies

Liver sinusoidal endothelial cells (LSECs) are highly specialized endothelial cells that form the interface between the hepatic vasculature and parenchymal cells, playing a crucial role in maintaining hepatic homeostasis. Under pathological conditions, LSECs undergo capillarization, marked by the loss of fenestrae and formation of a basement membrane, thereby impairing microcirculation and promoting fibrosis. Beyond capillarization, LSECs experience a spectrum of pathological changes-including angiogenesis, endothelial-to-mesenchymal transition (EndMT), autophagy, and senescence-all of which contribute to fibrogenesis through distinct molecular pathways. Moreover, LSECs orchestrate liver fibrotic remodeling through dynamic crosstalk with hepatic stellate cells (HSCs), hepatocytes, Kupffer cells, and immune cells, exerting both pro- and anti-fibrotic effects. This review comprehensively summarizes LSECs dysfunction in hepatic fibrosis, with a particular focus on intercellular communication and emerging therapeutic strategies. Elucidating the regulatory networks that govern LSECs behavior may uncover new opportunities for the diagnosis and treatment of chronic liver disease.

New insights into therapeutic strategies for targeting hepatic macrophages to alleviate liver fibrosis

Liver fibrosis is a wound-healing response induced by persistent liver damage, resulting from complex multicellular interactions and multifactorial networks. Without intervention, it can progress to cirrhosis and even liver cancer. Current understanding suggests that liver fibrosis is reversible, making it crucial to explore effective therapeutic strategies for its alleviation. Chronic inflammation serves as the primary driver of liver fibrosis, with hepatic macrophages playing a dual role depending on their polarization state. This review summarizes various prevention and therapeutic strategies targeting hepatic macrophages in the context of liver fibrosis. These strategies include inhibition of macrophage recruitment, modulation of macrophage activation and polarization, regulation of macrophage metabolism, and induction of phagocytosis and autophagy in hepatic macrophages. Additionally, we discuss the communication between hepatic macrophages, hepatocytes, and hepatic stellate cells (HSCs), as well as the current clinical application of anti-fibrotic drugs targeting macrophages. The goal is to identify effective therapeutic targets at each stage of macrophage participation in liver fibrosis development, with the aim of using hepatic macrophages as a target for liver fibrosis treatment.

Deficiency of myeloid NPC1 exacerbates liver injury and fibrosis by impairing macrophage efferocytosis

INTRODUCTION

Niemann-Pick C1 (NPC1), a lysosomal cholesterol transport protein, is required for efficient efferocytosis. Patients with Npc1 mutation are frequently accompanied with hepatic symptoms, including hepatomegaly, elevated liver transaminases, or even acute liver failure, but the pathogenic mechanism remains unknown.

OBJECTIVES

Our work aims to characterize the functional role of myeloid NPC1 in liver injury and elucidate its underlying mechanism.

METHODS

Analyses of injured livers from patients with liver diseases and mouse models were conducted to examine NPC1 expression. Myeloid cell-specific Npc1 knockout mice were constructed to determine the functional role of macrophage NPC1 in liver injury. Isolated macrophages were subjected to in vitro mechanistical assays.

RESULTS

We found that NPC1 is mainly expressed in hepatic macrophages. Its mRNA and protein expression are significantly elevated in injured livers from both patients and mouse models. Tissue-specific deletion of myeloid Npc1 increased liver inflammation, levels of serum liver function enzymes, and liver fibrosis in mouse models of liver injury induced by carbon tetrachloride (CCl4) injection and methionine-and-choline-deficient (MCD) diets. Further analyses indicate that Npc1 deficiency in mouse models of liver injury resulted in increased levels of serum HMGB1 and mitochondrial DNA, promoted hepatic macrophage proinflammatory activation, M1 polarization, led to overproduction of hepatic inflammatory cytokines/chemokines, e.g. CCL2 and STING/NFκB pathway activation. In vitro mechanistical studies reveal that Npc1-deficient macrophages exhibited inefficient efferocytosis, partly due to impaired cargo degradation.

CONCLUSIONS

These findings indicate that elevated expression of myeloid NPC1 in liver diseases protects liver from injury by promoting macrophage efferocytosis of damaged cells. Dysfunction of NPC1 aggravates liver injury, suggesting that NPC1 may be a potential therapeutic target for treating liver diseases.

Crosstalk between Hepatic Stellate Cells and Hepatic Macrophages in Metabolic Dysfunction-Associated Steatohepatitis

Metabolic dysfunction-associated steatotic liver disease is the most prevalent liver condition worldwide. Its more severe manifestation, metabolic dysfunction-associated steatohepatitis (MASH), is accompanied by distinctive hepatocellular injury and inflammation with fibrosis. The involvement of chronic inflammation and accompanying immune cell activation in the maturation phases of MASH progression, mediated through hepatic stellate cells (HSCs), plays a central role. This review highlights the detailed molecular and cellular mechanisms of MASH, with special attention to the dynamic dialogue between HSCs and hepatic macrophages. This review will help narrow the existing gaps, with a summary of key roles HSCs and hepatic macrophages play within liver immunity to inflammation, discussing critical intercellular communication pathways as well as proposing new venues for research toward a better understanding of MASH pathobiology, which could pave ways toward breakthroughs in the clinical condition.

Extracellular vesicle-dependent crosstalk between hepatic stellate cells and Kupffer cells promotes their mutual activation

BACKGROUND & AIMS

Hepatic fibrosis results from hepatic stellate cell (HSC) activation and excessive extracellular matrix (ECM) deposition, driven by chronic inflammation. Kupffer cells (KCs) play a central role in HSC activation. We previously showed that HSC-secreted factors, particularly extracellular vesicles (EVs), activate KCs. However, the reciprocal effects of activated KCs on HSCs remain poorly understood. This study investigates the bidirectional crosstalk between HSCs and KCs, focusing on the role of KC-derived EVs in regulating HSC activation and fibrosis progression.

METHODS

Primary HSCs and KCs were isolated from male Wistar rats. HSCs were co-cultured with KCs for 24 h to assess inflammatory and activation markers. LPS-stimulated KC-derived EVs and controls were administered to HSCs on day 1. LPS and the Toll-like receptor 4 (TLR4) inhibitor TAK-242 were used to investigate the intercellular communication in detail.

RESULTS

Co-cultured HSCs and KCs showed mutual activation, demonstrated by elevated inflammatory markers in both cell types and enhanced HSC pro-fibrotic activation. Pro-inflammatory (LPS)-activated KCs amplified HSC activation in a TLR4-dependent fashion. Part of this augmented HSC activation was attributed to EVs.

CONCLUSIONS

In co-culture, KCs and HSCs show mutual activation in a TLR4-dependent fashion. This bidirectional activation is augmented by pro-inflammatory mediators. KC-derived EVs (partially) activate HSCs, which might contribute to progression of liver fibrosis in vivo. Modulating KC activation, such as by blocking TLR4 signaling, may alter EV secretion or cargo composition, reducing HSC activation and fibrosis progression. Targeting this EV-mediated crosstalk could provide novel therapeutic strategies for liver fibrosis.

Hepatic stellate cells: balancing homeostasis, hepatoprotection and fibrogenesis in health and disease

In the past decades, the pathogenic role of hepatic stellate cells (HSCs) in the development of liver fibrosis and its complications has been deeply characterized, rendering HSCs a primary target for antifibrotic therapies. By contrast, the beneficial roles of HSCs in liver homeostasis and liver disease are only beginning to emerge, revealing critical regulatory and fibrosis-independent functions in hepatic zonation, metabolism, injury, regeneration and non-parenchymal cell identity. Here, we review how HSC mediators, such as R-spondin 3, hepatocyte growth factor and bone morphogenetic proteins, regulate critical and homeostatic liver functions in health and disease via cognate receptors in hepatocytes, Kupffer cells and endothelial cells. We highlight how the balance shifts from protective towards fibropathogenic HSC mediators during the progression of chronic liver disease (CLD) and the impact of this shifted balance on patient outcomes. Notably, the protective roles of HSCs are not accounted for in current therapeutic concepts for CLD. We discuss the concept that reverting the HSC balance from fibrogenesis towards hepatoprotection might represent a novel holistic treatment approach to inhibit fibrogenesis and restore epithelial health in CLD simultaneously.

Immunological mechanisms and emerging therapeutic targets in alcohol-associated liver disease

Alcohol-associated liver disease (ALD) is a major global health challenge, with inflammation playing a central role in its progression. As inflammation emerges as a critical therapeutic target, ongoing research aims to unravel its underlying mechanisms. This review explores the immunological pathways of ALD, highlighting the roles of immune cells and their inflammatory mediators in disease onset and progression. We also examine the complex interactions between inflammatory cells and non-parenchymal liver cells, as well as their crosstalk with extra-hepatic organs, including the gut, adipose tissue, and nervous system. Furthermore, we summarize current clinical research on anti-inflammatory therapies and discuss promising therapeutic targets. Given the heterogeneity of ALD-associated inflammation, we emphasize the need for precision medicine to optimize treatment strategies and improve patient outcomes.

Knowledge landscape of macrophage research in liver fibrosis: a bibliometric review of the literature from WoSCC

Recent insights into the immune response in fibrosis have provided valuable perspectives for the treatment of liver fibrosis. Macrophages, as the most abundant immune cells in the liver, are key drivers of liver fibrosis. They are extensively involved in tissue damage, chronic inflammation, and the progression and regression of liver fibrosis. This study aims to conduct a bibliometric analysis and literature review on the mechanisms by which macrophages contribute to liver fibrosis. Specifically, we analyzed a bibliometric dataset comprising 1,312 papers from 59 countries, 1,872 institutions, and 9,784 authors. Keyword co-occurrence analysis identified key research hotspots, including the role of macrophage subtypes in obesity-related metabolic disorders, the crosstalk between macrophages and hepatic stellate cells through mechanoimmunology, emerging strategies for immune modulation targeting macrophages to promote fibrosis regression and liver regeneration, and new discoveries regarding macrophage crosstalk with other immune cells. In conclusion, this study provides a visual analysis of the current research landscape, hotspots, and trends in the field of macrophages and liver fibrosis, and discusses future directions for further exploration in this area.

The role of hepatic sinusoidal microenvironment in NASH: pathogenesis, animal models, and therapeutic prospects

The incidence of nonalcoholic steatohepatitis (NASH) is increasing annually, posing a significant threat to human health. NASH is typified by hepatic steatosis, inflammation, and hepatocellular injury, frequently culminating in fibrosis and cirrhosis. Yet, the precise pathogenesis of NASH remains to be fully elucidated. The hepatic sinusoid, which serves as the fundamental structural and functional unit of the liver, is intricately composed of endothelial cells, Kupffer cells, and hepatic stellate cells. Consequently, the homeostasis of the hepatic sinusoidal microenvironment may exert a pivotal influence on the progression and prognosis of NASH. However, the limitations of current NASH animal models have significantly impeded advancements in understanding the disease's pathogenesis and the development of effective therapeutic interventions. In light of these challenges, this review endeavors to delve deeper into the critical role of hepatic sinusoidal microenvironment homeostasis in the pathogenesis of NASH, critically analyze the commonly employed animal models, and comprehensively summarize the most recent and promising developments in drug research and development. It is anticipated that these efforts will collectively expedite the advancement of the field of NASH research and therapeutic innovation.

LncRNA gm40262 promotes liver fibrosis and parasite growth through the gm40262-miR-193b-5p-TLR4/Col1α1 axis

Alveolar echinococcosis (AE) is a severe and life-threatening parasitic disease caused by Echinococcus multilocularis. Liver fibrosis is a significant pathological feature of advanced AE, characterized by the excessive production and accumulation of extracellular matrix (ECM). However, the precise underlying mechanism remains largely unknown. In this study, we show that the long noncoding RNA gm40262, predominantly expressed in hepatic stellate cells (HSCs), is upregulated in AE. Interestingly, its knockdown leads to liver fibrosis resolution, accompanied by a substantial suppression of parasite growth. Gm40262 functions by targeting miR-193b-5p to activate HSCs and stimulate their proliferation in a TGF-β-dependent manner, thereby promoting ECM production by upregulating Col1α1. Moreover, gm40262 is also involved in inflammation through the gm40262-miR-193b-5p-TLR4 axis. Our findings suggest that gm40262 plays a pivotal role in parasite-induced liver fibrosis through multiple mechanisms, highlighting its potential as a therapeutic target for hepatic fibrosis.

IMPORTANCE

Echinococcus multilocularis is a tiny parasite with significant medical implications. The chronic parasitism of E. multilocularis in the liver generally leads to liver fibrosis, but the underlying mechanisms are poorly understood. We herein show that gm40262, a long noncoding RNA predominantly expressed in hepatic stellate cells (HSCs), is involved in hepatic fibrogenesis during infection by activating HSCs and promoting extracellular matrix production. The gm40262-orchestrating fibrogenesis occurs through the gm40262-miR-193b-5p-TLR4 and gm40262-miR-193b-5p-Col1α1 axes. The knockdown of gm40262 remarkably alleviates liver fibrosis, with decreased parasite growth. Our findings reveal a key role of gm40262 in liver fibrosis during E. multilocularis infection, rendering it a therapeutic target for hepatic fibrosis.

Mindin orchestrates the macrophage-mediated resolution of liver fibrosis in mice

BACKGROUND & AIMS

Liver disease that progresses to cirrhosis is an enormous health problem worldwide. The extracellular matrix protein Mindin is known to have immune functions, but its role in liver homeostasis remains largely unexplored. We aimed to characterize the role of Mindin in the regulation of liver fibrosis.

APPROACH & RESULTS

Mindin was upregulated in mice with carbon tetrachloride (CCl4) or thioacetamide (TAA)-induced liver fibrosis, and was primarily expressed in hepatocytes. Global Mindin knockout mice were generated, which were susceptible to liver fibrosis. Notably, Mindin failed to activate hepatic stellate cells directly; however, it played a role in promoting the recruitment and phagocytosis of macrophages, and caused a phenotypic switch toward restorative macrophages during liver fibrosis. Furthermore, Mindin was found to bind to the αM-I domain of CD11b/CD18 heterodimeric receptors. To further explore this mechanism, we created Mindin and CD11b double-knockout (DKO) mice. In DKO mice, phagocytosis was further reduced, and liver fibrosis was markedly exacerbated.

CONCLUSIONS

Mindin promotes the resolution of liver fibrosis and the Mindin/CD11b axis might represent a novel target for the macrophage-mediated regression of liver 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.

Platelet C3G protects from liver fibrosis, while enhancing tumor growth through regulation of the immune response

Primary liver cancer usually occurs in the context of chronic liver disease (CLD), in association with fibrosis. Platelets have emerged as important regulators of CLD and liver cancer, although their precise function and mechanism of action need to be clarified. C3G (RapGEF1) regulates platelet activation, adhesion, and secretion. Here we evaluate the role of platelet C3G in chemically induced fibrosis and liver cancer associated with fibrosis using genetically modified mouse models. We found that while overexpression of full-length C3G in platelets decreased liver fibrosis induced by chronic treatment with CCl4, overexpressed C3G lacking the catalytic domain did not, although in both cases platelet recruitment to the liver was similar. In addition, C3G deletion in platelets (PF4-C3GKO mouse model) increased CCl4-induced liver damage and hepatic fibrosis, reducing liver platelets and macrophages. Moreover, early liver immune response to CCl4 was altered in PF4-C3GKO mice, with a remarkable lower activation of macrophages and increased monocyte-derived macrophages compared to WT mice. On the other hand, in response to DEN+CCl4, PF4-C3G WT mice exhibited more and larger liver tumors than PF4-C3GKO mice, accompanied by the presence of more platelets, despite having less fibrosis in previous steps. Liver immune cell populations were also differentially regulated in PF4-C3GKO mice, highlighting the higher number of macrophages, likely with a pro-inflammatory phenotype, present in the liver in response to chronic DEN+CCl4 treatment. Proteins upregulated or downregulated in platelet-rich plasma from PF4-C3GKO compared to WT mice might regulate the immune response and tumor development. In this regard, enrichment analyses using proteomic data showed changes in several proteins involved in platelet activation and immune response pathways. Additionally, the higher secretion of CD40L by PF4-C3GKO platelets could contribute to their antitumor effect. Therefore, platelet C3G presents antifibrotic and protumor effects in the liver, likely mediated by changes in the immune response. © 2025 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Tissue macrophages: origin, heterogenity, biological functions, diseases and therapeutic targets

Macrophages are immune cells belonging to the mononuclear phagocyte system. They play crucial roles in immune defense, surveillance, and homeostasis. This review systematically discusses the types of hematopoietic progenitors that give rise to macrophages, including primitive hematopoietic progenitors, erythro-myeloid progenitors, and hematopoietic stem cells. These progenitors have distinct genetic backgrounds and developmental processes. Accordingly, macrophages exhibit complex and diverse functions in the body, including phagocytosis and clearance of cellular debris, antigen presentation, and immune response, regulation of inflammation and cytokine production, tissue remodeling and repair, and multi-level regulatory signaling pathways/crosstalk involved in homeostasis and physiology. Besides, tumor-associated macrophages are a key component of the TME, exhibiting both anti-tumor and pro-tumor properties. Furthermore, the functional status of macrophages is closely linked to the development of various diseases, including cancer, autoimmune disorders, cardiovascular disease, neurodegenerative diseases, metabolic conditions, and trauma. Targeting macrophages has emerged as a promising therapeutic strategy in these contexts. Clinical trials of macrophage-based targeted drugs, macrophage-based immunotherapies, and nanoparticle-based therapy were comprehensively summarized. Potential challenges and future directions in targeting macrophages have also been discussed. Overall, our review highlights the significance of this versatile immune cell in human health and disease, which is expected to inform future research and clinical practice.

Anti-tumor immunity relies on targeting tissue homeostasis through monocyte-driven responses rather than direct tumor cytotoxicity

Background

Metabolic dysfunction-associated fatty liver disease (MAFLD) can progress to hepatocellular carcinoma (HCC), yet the immune mechanisms driving this transition remain unclear.

Methods

In a chronic Western diet (WD) mouse model, we performed single-nuclei RNA sequencing to track MAFLD progression into HCC and subsequent tumor inhibition upon dietary correction.

Results

Carcinogenesis begins during MAFLD, with tumor cells entering dormancy when HCC is mitigated. Rather than purely tolerogenic, the liver actively engages immune responses targeting myofibroblasts, fibroblasts and hepatocytes to maintain tissue homeostasis. Cytotoxic cells contribute to turnover of liver cells but do not primarily target the tumor. NKT cells predominate under chronic WD, while monocytes join them in HCC progression on a WD. Upon dietary correction, monocyte-driven immunity confers protection against HCC through targeting tissue homeostatic pathways and antioxidant mechanisms. Crucially, liver tissue response-not merely immune activation-dictates whether tumors grow or regress, emphasizing the importance of restoring liver tissue integrity. Also, protection against HCC is linked to a distinct immunological pattern, differing from healthy controls, underscoring the need for immune reprogramming.

Conclusion

These findings reveal the dual roles of similar pathways, where immune patterns targeting different cells shape distinct outcomes. Restoring tissue homeostasis and regeneration creates a tumor-hostile microenvironment, whereas tumor-directed approaches fail to remodel the TME. This underscores the need for tissue remodeling strategies in cancer prevention and treatment.

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.

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.

EGF receptor in organ development, tissue homeostasis and regeneration

The epidermal growth factor receptor (EGFR) is a protein embedded in the outer membrane of epithelial and mesenchymal cells, bone cells, blood and immune cells, heart cells, glia and stem neural cells. It belongs to the ErbB family, which includes three other related proteins: HER2/ErbB2/c-neu, HER3/ErbB3, and HER4/ErbB4. EGFR binds to seven known signaling molecules, including epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-α). This binding triggers the formation of receptor pairs (dimers), self-phosphorylation of EGFR, and the activation of several signaling pathways within the cell. These pathways influence various cellular processes like proliferation, differentiation, migration, and survival. EGFR plays a critical role in both development and tissue homeostasis, including tissue repair and adult organ regeneration. Altered expression of EGFR is linked to disruption of tissue homeostasis and various diseases, among which cancer. This review focuses on how EGFR contributes to the development of different organs like the placenta, gut, liver, bone, skin, brain, T cell regulation, pancreas, kidneys, mammary glands and lungs along with their associated pathologies. The involvement of EGFR in organ-specific branching morphogenesis process is also discussed. The level of EGFR activity and its impact vary across different organs. Factors as the affinity of its ligands, recycling or degradation processes, and transactivation by other proteins or environmental factors (such as heat stress and smoking) play a role in regulating EGFR activity. Understanding EGFR's role and regulatory mechanisms holds promise for developing targeted therapeutic strategies.

Inhibition of RAC1 activator DOCK2 ameliorates cholestatic liver injury via regulating macrophage polarisation and hepatic stellate cell activation

BACKGROUND

The Rho GTPase Rac family small GTPase 1 (RAC1) is considered a promising fibrotic therapeutic target, but the role of its activator, dedicator of cytokinesis 2 (DOCK2), in liver fibrosis is largely unknown. This study aimed to investigate the expression and role of DOCK2 in cholestasis-induced liver fibrosis and to further explore the potential mechanisms.

RESULTS

Cholestasis was induced in male C57BL/6 mice by bile duct ligation (BDL). DOCK2 knockdown was achieved by tail vein injection of adenovirus containing DOCK2-targeting shRNA. The effect of DOCK2 knockdown on cholestatic liver injury was evaluated at different time points after BDL. Hepatic DOCK2 expression gradually increased after BDL. Knockdown of DOCK2 reduced the necrotic area in BDL liver and downregulated serum levels of liver injury indicators. At 3d post-BDL (acute phase), DOCK2 knockdown alleviated M1 macrophage inflammation in the liver, as evidenced by reduced infiltrating iNOS + macrophages and inflammatory cytokines and mitigated NLRP3 inflammasome activation. At 14d post-BDL (chronic phase), DOCK2 knockdown suppressed hepatic stellate cell (HSC) activation and liver fibrosis as indicated by decreased α-SMA + HSCs and extracellular matrix deposition. In vitro experiments further demonstrated that DOCK2 knockdown suppressed M1 macrophage polarisation and HSC to myofibroblast transition, accompanied by inhibition of RAC1 activation.

CONCLUSIONS

In summary, this study demonstrates for the first time that the RAC1 activator DOCK2 regulates M1 macrophage polarisation and hepatic stellate cell activation to promote cholestasis-induced liver inflammation and fibrosis, suggesting that DOCK2 may be a potential therapeutic target in cholestatic liver injury.

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

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

AdipoRon mitigates liver fibrosis by suppressing serine/glycine biosynthesis through ATF4-dependent glutaminolysis

AdipoRon has been validated for its ability to reverse liver fibrosis, yet the underlying mechanisms remain to be thoroughly investigated. Collagen, predominantly synthesized and secreted in hepatic stellate cells (HSCs), relies on glycine as a crucial constituent. Activating transcription factor 4 (ATF4) serves as a pivotal transcriptional regulator in amino acid metabolism. Therefore, our objective is to explore the impact of AdipoRon on ATF4-mediated endoplasmic reticulum stress and amino acid metabolism in HSCs. We induced liver fibrosis in mice through intraperitoneal injection of CCl4 and administered AdipoRon (50 mg/kg) via gavage. In vitro studies were predominantly conducted using LX-2 cells. Our findings demonstrated that AdipoRon effectively suppressed ATF4-mediated endoplasmic reticulum stress in HSCs and assumed a crucial role in hindering serine/glycine biosynthesis. Interestingly, this inhibitory effect of AdipoRon on serine/glycine biosynthesis is regulated by PSAT1-mediated glutaminolysis, resulting in a subsequent decrease in collagen synthesis within HSCs. This study provides potential mechanistic insights into the treatment of liver fibrosis with AdipoRon.

Immunoregulation of Liver Fibrosis: New Opportunities for Antifibrotic Therapy

Liver fibrosis develops in response to chronic liver injury and is characterized by a sustained inflammatory response that leads to excessive collagen deposition by myofibroblasts. The fibrogenic response is governed by the release of inflammatory mediators from innate, adaptive, and innate-like lymphoid cells and from nonprofessional immune cells (i.e., epithelial cells, hepatic myofibroblasts, and liver sinusoidal endothelial cells). Upon removal of the underlying cause, liver fibrosis can resolve via activation of specific immune cell subsets. Despite major advances in the understanding of fibrosis pathogenesis, there is still no approved antifibrotic therapy. This review summarizes our current knowledge of the immune cell landscape and the inflammatory mechanisms underlying liver fibrosis progression and regression. We discuss how reprogramming immune cell phenotype, in particular through targeting selective inflammatory pathways or modulating cell-intrinsic metabolism, may be translated into antifibrogenic therapies.

Identifying specific functional roles for senescence across cell types

Cellular senescence plays critical roles in aging, regeneration, and disease; yet, the ability to discern its contributions across various cell types to these biological processes remains limited. In this study, we generated an in vivo genetic toolbox consisting of three p16Ink4a-related intersectional genetic systems, enabling pulse-chase tracing (Sn-pTracer), Cre-based tracing and ablation (Sn-cTracer), and gene manipulation combined with tracing (Sn-gTracer) of defined p16Ink4a+ cell types. Using liver injury and repair as an example, we found that macrophages and endothelial cells (ECs) represent distinct senescent cell populations with different fates and functions during liver fibrosis and repair. Notably, clearance of p16Ink4a+ macrophages significantly mitigates hepatocellular damage, whereas eliminating p16Ink4a+ ECs aggravates liver injury. Additionally, targeted reprogramming of p16Ink4a+ ECs through Kdr overexpression markedly reduces liver fibrosis. This study illuminates the functional diversity of p16Ink4a+ cells and offers insights for developing cell-type-specific senolytic therapies in the future.

ATG16L1 Depletion-Mediated Activation of the TRAF1 Signaling in Macrophages Aggravates Liver Fibrosis

Background: Hepatic macrophages play an indispensable role in liver pathophysiology, serving as key orchestrators of both liver injury and repair processes. ATG16L1 (autophagy-related 16 like 1) has emerged as a novel and critical autophagy marker. In macrophages, ATG16L1 assumes a particularly crucial role. The current understanding of how macrophage ATG16L1 regulates liver inflammation in the context of liver fibrosis is unclear. Methods: This study included clinical patient samples of liver fibrosis and established a murine model with myeloid-specific Atg16l1 knockout, creating a mouse model of liver fibrosis. Employing RNA sequencing, we sought to elucidate the mechanisms of macrophage ATG16L1 in liver fibrosis by identifying critical signaling pathways. To assess the influence of macrophage ATG16L1 on hepatocyte apoptosis and hepatic stellate cell (HSC) activation, we constructed a dedicated culture system. Ultimately, the introduction of mice with myeloid-specific Atg16l1 knock-in substantiated the protective role of myeloid-specific Atg16l1 against inflammatory signaling, hepatocyte apoptosis, and activation of HSCs. Results: An upregulation of the ATG16L1 signal was observed in the liver tissues of patients with liver fibrosis and in fibrotic mice, predominantly localized to hepatic macrophages. In Atg16l1 ΔMφ mice afflicted with liver fibrosis, we detected exacerbated liver damage, evidenced by heightened inflammatory signal expression, increased hepatocyte apoptosis, and enhanced activation of HSCs. The absence of macrophage Atg16l1 was found to result in elevated TNF receptor-associated factor 1 (TRAF1) signaling, triggering inflammatory activation, intensifying hepatocyte apoptosis, and facilitating HSC activation through the transforming growth factor beta 1 (TGF-β1) signaling. The detrimental effects of macrophage Atg16l1 depletion were demonstrated to be mitigated upon Atg16l1 reintroduction. Conclusions: This research delved into the mechanisms by which the macrophage ATG16L1 signal influences inflammatory signaling, hepatocyte apoptosis, and activation of HSCs in liver fibrosis. Consequently, it offers theoretical substantiation and an experimental groundwork for the identification of biological targets for therapeutic intervention in liver fibrosis.

The role of macrophages in liver fibrosis: composition, heterogeneity, and therapeutic strategies

Macrophages, the predominant immune cells in the liver, are essential for maintaining hepatic homeostasis and responding to liver injury caused by external stressors. The hepatic macrophage population is highly heterogeneous and plastic, mainly comprised of hepatic resident kuffer cells (KCs), monocyte-derived macrophages (MoMφs), lipid-associated macrophages (LAMs), and liver capsular macrophages (LCMs). KCs, a population of resident macrophages, are localized in the liver and can self-renew through in situ proliferation. However, MoMφs in the liver are recruited from the periphery circulation. LAMs are a self-renewing subgroup of liver macrophages near the bile duct. While LCMs are located in the liver capsule and derived from peripheral monocytes. LAMs and LCMs are also involved in liver damage induced by various factors. Hepatic macrophages exhibit distinct phenotypes and functions depending on the specific microenvironment in the liver. KCs are critical for initiating inflammatory responses after sensing tissue damage, while the MoMφs infiltrated in the liver are implicated in both the progression and resolution of chronic hepatic inflammation and fibrosis. The regulatory function of liver macrophages in hepatic fibrosis has attracted significant interest in current research. Numerous literatures have documented that the MoMφs in the liver have a dual impact on the progression and resolution of liver fibrosis. The MoMφs in the liver can be categorized into two subtypes based on their Ly-6C expression level: inflammatory macrophages with high Ly-6C expression (referred to as Ly-6Chi subgroup macrophages) and reparative macrophages with low Ly-6C expression (referred to as Ly-6Clo subgroup macrophages). Ly-6Chi subgroup macrophages are conducive to the occurrence and progression of liver fibrosis, while Ly-6Clo subgroup macrophages are associated with the degradation of extracellular matrix (ECM) and regression of liver fibrosis. Given this, liver macrophages play a pivotal role in the occurrence, progression, and regression of liver fibrosis. Based on these studies, treatment therapies targeting liver macrophages are also being studied gradually. This review aims to summarize researches on the composition and origin of liver macrophages, the macrophage heterogeneity in the progression and regression of liver fibrosis, and anti-fibrosis therapeutic strategies targeting macrophages in the liver.

Plasma MERTK Is a Promising Biomarker for the Diagnosis and Prognosis of Hepatitis B Virus-Related Acute-on-Chronic Liver Failure

BACKGROUND

Hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) has a high short-term mortality. This study aimed to determine the diagnostic and prognostic role of MER tyrosine kinase (MERTK) in patients with HBV-ACLF.

METHODS

Transcriptomics analysis evaluated MERTK expression and function during disease progression. The diagnostic and prognostic significance of MERTK for patients with HBV-ACLF were verified by enzyme-linked immunosorbent assay, area under the receiver operating characteristic curve (AUROC) analysis, and immunohistochemistry (IHC) of liver tissues.

RESULTS

MERTK mRNA was highly expressed in patients with HBV-ACLF compared to those with liver cirrhosis (LC), chronic hepatitis B (CHB), and normal controls (NC). Elevated MERTK mRNA predicted poor prognosis for HBV-ACLF at 28 and 90 days (AUROC = 0.814 and 0.731, respectively). Functional analysis showed MERTK was significantly associated with toll-like receptor and inflammatory signaling and several key biological processes. External validation with 285 plasma subjects confirmed the high diagnostic accuracy of plasma MERTK for HBV-ACLF (AUROC = 0.859) and potential prognostic value for 28- and 90-day mortality rates (AUROC = 0.673 and 0.644, respectively). Risk stratification analysis indicated higher mortality risk for patients with plasma MERTK level above the cutoff value. Moreover, IHC staining showed increasing MERTK expression from NC, CHB, and LC to HBV-ACLF.

CONCLUSIONS

MERTK shows promise as a candidate biomarker for early diagnosis and prognosis of HBV-ACLF.

A double-blind, randomized control trial to investigate the therapeutic potential of garlic scapes for high apoprotein E levels in a high-Fat diet-induced hypercholesteremic rat model

Hypercholesteremia is the main contributor to metabolic diseases, including obesity, hypertension, and diabetes, which are the primary global sources of morbidity and death rates. Garlic scapes, a member of the Allium sativum family and a rich source of antioxidants, are utilized in various cuisine preparations due to their unique flavors and tastes. The current study examined garlic scape powder's effect on apoprotein E and its ability to decrease cholesterol. In an in vivo experiment, normal, healthy Wistar albino rats (weeks) were divided into a negative control group (NC, n = 10) and a high-fat diet-raised group (n = 50) until they achieved cholesterol ≥250 mg/dL. Hypercholesteremic rats were further divided randomly into five groups: positive control (PC), standard group (fenofibrate 20 mg/kg bwt), and treatment groups G1, G2, and G3 that were administered with garlic scape powder 400 mg, 800 mg, and 1200 mg/kg bwt orally, respectively, for 3 months. The blood samples were examined for cholesterol, triglycerides, high-density lipoproteins (HDLs), low-density lipoproteins, apoprotein E, albumin levels, alanine aminotransferase (ALT), and aspartate aminotransferase (AST). The liver tissues of the rats were subjected to histopathology. The lipid profile was assessed using serum kit techniques, whereas an ELISA kit was used to evaluate apoprotein E, and a serum kit was used to estimate ALT and AST. In comparison to all other groups except NC, the highest dose of 1200 mg/kg bwt of garlic scapes significantly (p ≤ .05) increased serum insulin (13.66 ± 0.72 μU/mL), apoprotein E levels (6.08 ± 0.10 mg/dL), HDL (42.1 ± 1.81 mg/dL), and reduce TG (88.7 ± 1.64 mg/dL) and decreased overall cholesterol levels (67.9 ± 1.17 mg/dL). Except for NC, all treatment groups had significantly (p ≤ .05) lower ALT and AST values than PC. To sum up, powdered garlic scapes may be a great way to avoid hyperlipidemia, which raises the risk of cardiovascular illnesses. ALT and AST levels were significantly (p ≤ .05) reduced in all treatment groups compared to PC, except for NC. In conclusion, garlic scape powder may be an excellent source to prevent hyperlipidemia, a risk factor for cardiovascular diseases. In addition, powdered garlic scapes supplementation at high doses may be used as an alternative natural source in functional foods to halt hyperlipidemia without liver toxicity in the long term.

The role of forkhead box M1-methionine adenosyltransferase 2 A/2B axis in liver inflammation and fibrosis

Methionine adenosyltransferase 2 A (MAT2A) and MAT2B are essential for hepatic stellate cells (HSCs) activation. Forkhead box M1 (FOXM1) transgenic mice develop liver inflammation and fibrosis. Here we examine if they crosstalk in male mice. We found FOXM1/MAT2A/2B are upregulated after bile duct ligation (BDL) and carbon tetrachloride (CCl4) treatment in hepatocytes, HSCs and Kupffer cells (KCs). FDI-6, a FOXM1 inhibitor, attenuates the development and reverses the progression of CCl4-induced fibrosis while lowering the expression of FOXM1/MAT2A/2B, which exert reciprocal positive regulation on each other transcriptionally. Knocking down any of them lowers HSCs and KCs activation. Deletion of FOXM1 in hepatocytes, HSCs, and KCs protects from BDL-mediated inflammation and fibrosis comparably. Interestingly, HSCs from Foxm1Hep-/-, hepatocytes from Foxm1HSC-/-, and HSCs and hepatocytes from Foxm1KC-/- have lower FOXM1/MAT2A/2B after BDL. This may be partly due to transfer of extracellular vesicles between different cell types. Altogether, FOXM1/MAT2A/MAT2B axis drives liver inflammation and fibrosis.

Sphingosine Kinase 1 Aggravates Liver Fibrosis by Mediating Macrophage Recruitment and Polarization

BACKGROUND & AIMS

Sphingosine kinase 1 (SphK1) has distinct roles in the activation of Kupffer cells and hepatic stellate cells in liver fibrosis. Here, we aim to investigate the roles of SphK1 on hepatic macrophage recruitment and polarization in liver fibrosis.

METHODS

Liver fibrosis was induced by carbon tetrachloride in wild-type and SphK1-/- mice to study the recruitment and polarization of macrophages. The effects of SphK1 originated from macrophages or other liver cell types on liver fibrosis were further strengthened by bone marrow transplantation. The direct effects of SphK1 on macrophage polarization were also investigated in vitro. Expression analysis of SphK1 and macrophage polarization index was conducted with human liver samples.

RESULTS

SphK1 deletion attenuated the recruitment of hepatic macrophages along with reduced M1 and M2 polarization in mice induced by carbon tetrachloride. SphK1 deficiency in endogenous liver cells attenuated macrophage recruitment via C-C motif chemokine ligand 2. Macrophage SphK1 activated the ASK1-JNK1/2-p38 signaling pathway to promote M1 polarization. Furthermore, macrophage SphK1 downregulated small ubiquitin-like modifier-specific peptidase1 to decrease de-SUMOylation of Kruppel-like factor 4 to promote M2 polarization. Finally, we confirmed that SphK1 expression was elevated and positively correlated with macrophage M1 and M2 polarization in human fibrosis livers.

CONCLUSIONS

Our findings demonstrated that SphK1 aggravated liver fibrosis by promoting macrophage recruitment and M1/M2 polarization. SphK1 in macrophages is a potential therapeutic target for the treatment of liver fibrosis.

Oxysophoridine inhibits oxidative stress and inflammation in hepatic fibrosis via regulating Nrf2 and NF-κB pathways

BACKGROUND

Hepatic fibrosis (HF) runs through multiple stages of liver diseases and promotes these diseases progression. Oxysophoridine (OSR), derived from Sophora alopecuroides l., is a bioactive alkaloid that has been reported to antagonize alcoholic hepatic injury. However, whether OSR suppresses HF and the mechanisms involved in Nrf2 remain unknown.

PURPOSE

Since the dysregulation of inflammation and oxidative stress is responsible for the excessive accumulation of extracellular matrix (ECM) and fibrosis in the liver. We hypothesized that OSR may attenuate HF by inhibiting inflammation and oxidative stress through activating Nrf2 signaling.

METHODS

In this study, we employed LPS-stimulated HSC-T6 cells, RAW264.7 cells, and a CCl4-induced C57BL/6 mouse fibrotic model to evaluate its suppressing inflammation and oxidative stress, as well as fibrosis.

RESULTS

The result showed that OSR significantly reduced α-SMA and TGF-β1 at a low dose of 10 μM in vitro and at a dose of 50 mg/kg in vivo, which is comparable to Silymarin, the only Chinese herbal active ingredient that has been marketed for anti-liver fibrosis. Moreover, OSR effectively suppressed the expression of iNOS at a dose of 10 μM and COX-2 at a dose of 40 μM, respectively. Furthermore, OSR demonstrated inhibitory effects on the IL-1β, IL-6, and TNF-α in vitro and almost extinguished cytokine storm in vivo. OSR exhibited antioxidative effects by reducing MDA and increasing GSH, thereby protecting the cell membrane against oxidative damage and reducing LDH release. Moreover, OSR effectively upregulated the protein levels of Nrf2, HO-1, and p62, but decreased p-NF-κB p65, p-IκBα, and Keap1. Alternatively, mechanisms involved in Nrf2 were verified by siNrf2 interference, siNrf2 interference revealed that the anti-fibrotic effect of OSR was attributed to its activation of Nrf2.

CONCLUSION

The present study provided an effective candidate for HF involved in both activation of Nrf2 and blockage of NF-κB, which has not been reported in the published work. The present study provides new insights for the identification of novel drug development for HF.

Progranulin: A promising biomarker and therapeutic target for fibrotic diseases

Progranulin (PGRN), a multifunctional growth factor-like protein expressed by a variety of cell types, serves an important function in the physiologic and pathologic processes of fibrotic diseases, including wound healing and the inflammatory response. PGRN was discovered to inhibit pro-inflammation effect by competing with tumor necrosis factor-alpha (TNF-α) binding to TNF receptors. Notably, excessive tissue repair in the development of inflammation causes tissue fibrosis. Previous investigations have indicated the significance of PGRN in regulating inflammatory responses. Recently, multiple studies have shown that PGRN was linked to fibrogenesis, and was considered to monitor the formation of fibrosis in multiple organs, including liver, cardiovascular, lung and skin. This paper is a comprehensive review summarizing our current knowledge of PGRN, from its discovery to the role in fibrosis. This is followed by an in-depth look at the characteristics of PGRN, consisting of its structure, basic function and intracellular signaling. Finally, we will discuss the potential of PGRN in the diagnosis and treatment of fibrosis.

Crosstalk in extrahepatic and hepatic system in NAFLD/NASH

Non-alcoholic fatty liver disease (NAFLD) has emerged as the most prevalent chronic liver disease globally. Non-alcoholic steatohepatitis (NASH) represents an extremely progressive form of NAFLD, which, without timely intervention, may progress to cirrhosis or hepatocellular carcinoma. Presently, a definitive comprehension of the pathogenesis of NAFLD/NASH eludes us, and pharmacological interventions targeting NASH specifically remain constrained. The aetiology of NAFLD encompasses a myriad of external factors including environmental influences, dietary habits and gender disparities. More significantly, inter-organ and cellular interactions within the human body play a role in the development or regression of the disease. In this review, we categorize the influences affecting NAFLD both intra- and extrahepatically, elaborating meticulously on the mechanisms governing the onset and progression of NAFLD/NASH. This exploration delves into progress in aetiology and promising therapeutic targets. As a metabolic disorder, the development of NAFLD involves complexities related to nutrient metabolism, liver-gut axis interactions and insulin resistance, among other regulatory functions of extraneous organs. It further encompasses intra-hepatic interactions among hepatic cells, Kupffer cells (KCs) and hepatic stellate cells (HSCs). A comprehensive understanding of the pathogenesis of NAFLD/NASH from a macroscopic standpoint is instrumental in the formulation of future therapies for NASH.

Neutrophil extracellular traps induce intrahepatic thrombotic tendency and liver damage in cholestatic liver disease

BACKGROUND

Cholestatic liver diseases induce local and systemic hypercoagulation, with neutrophil extracellular traps (NETs) serving as major drivers. These NETs have been linked to decreased liver function in patients with obstructive jaundice. However, the impact of NETs on liver hypercoagulation in cholestatic liver disease remains unknown.

METHODS

We utilized bile duct ligation to create experimental mice and analyzed NETs formation in the liver. Fibrin deposition, tissue factor expression, and inflammation in the liver were visualized through western blot and immunohistochemical techniques. LSECs were incubated with isolated NETs, and we detected endothelial procoagulant activity using coagulation protein production assays and measuring endothelial permeability. In both in vivo and in vitro settings, DNase I was applied to clarify the effect of NETs on intrahepatic hypercoagulability, hepatotoxicity, LSEC, and macrophage activation or injury.

RESULTS

Bile duct ligation mice exhibited significantly increased levels of NETs in liver tissue, accompanied by neutrophil infiltration, tissue necrosis, fibrin deposition, and thrombophilia compared to sham mice. Notably, NETs resulted in phosphatidylserine and tissue factor exposure on LSEC, enhancing coagulation Factor Xa and thrombin production. The enhanced procoagulant activity could be reversed by degrading NETs with DNase I. Additionally, NETs-induced permeability changes in LSECs, characterized by increased VE-cadherin expression and F-actin retraction, which could be rescued by DNase I. Meanwhile, NET formation is associated with KC activation and the formation of inflammatory factors.

CONCLUSIONS

NETs promote intrahepatic activation of coagulation and inflammation, leading to liver tissue injury. Strategies targeting NET formation may offer a potential therapeutic approach for treating cholestatic liver disease.

Targeting chronic liver diseases: Molecular markers, drug delivery strategies and future perspectives

Chronic liver inflammation, a pervasive global health issue, results in millions of annual deaths due to its progression from fibrosis to the more severe forms of cirrhosis and hepatocellular carcinoma (HCC). This insidious condition stems from diverse factors such as obesity, genetic conditions, alcohol abuse, viral infections, autoimmune diseases, and toxic accumulation, manifesting as chronic liver diseases (CLDs) such as metabolic dysfunction-associated steatotic liver disease (MASLD), metabolic dysfunction-associated steatohepatitis (MASH), alcoholic liver disease (ALD), viral hepatitis, drug-induced liver injury, and autoimmune hepatitis. Late detection of CLDs necessitates effective treatments to inhibit and potentially reverse disease progression. However, current therapies exhibit limitations in consistency and safety. A potential breakthrough lies in nanoparticle-based drug delivery strategies, offering targeted delivery to specific liver cell types, such as hepatocytes, Kupffer cells, and hepatic stellate cells. This review explores molecular targets for CLD treatment, ongoing clinical trials, recent advances in nanoparticle-based drug delivery, and the future outlook of this research field. Early intervention is crucial for chronic liver disease. Having a comprehensive understanding of current treatments, molecular biomarkers and novel nanoparticle-based drug delivery strategies can have enormous impact in guiding future strategies for the prevention and treatment of CLDs.

Microbial-derived Urolithin A Targets GLS1 to Inhibit Glutaminolysis and Attenuate Cirrhotic Portal Hypertension

BACKGROUND & AIMS

Cirrhotic portal hypertension (CPH) is the leading cause of mortality in patients with cirrhosis. Over 50% of patients with CPH treated with current clinical pharmacotherapy still present variceal bleeding or sometimes death owing to insufficient reduction in portal pressure. Elevated intrahepatic vascular resistance (IHVR) plays a fundamental role in increasing portal pressure. Because of its potent effect in reducing portal pressure and maintaining normal portal inflow to preserve liver function, lowering the IHVR is acknowledged as an optimal anti-CPH strategy but without clinical drugs. We aimed to investigate the protective effect of microbial-derived Urolithin A (UroA) in IHVR and CPH.

METHODS

Carbon tetrachloride or bile duct ligation surgery was administered to mice to induce liver fibrosis and CPH. 16S rRNA gene sequencing was used for microbial analysis. Transcriptomics and metabolomics analyses were employed to study the host and cell responses.

RESULTS

UroA was remarkably deficient in patients with CPH and was negatively correlated with disease severity. UroA deficiency was also confirmed in CPH mice and was associated with a reduced abundance of UroA-producing bacterial strain (Lactobacillus murinus, L. murinus). Glutaminolysis of hepatic stellate cells (HSCs) was identified as a previously unrecognized target of UroA. UroA inhibited the activity of glutaminase1 to suppress glutaminolysis, which counteracted fibrogenesis and contraction of HSCs and ameliorated CPH by relieving IHVR. Supplementation with UroA or L. murinus effectively ameliorated CPH in mice.

CONCLUSIONS

We for the first time identify the deficiency of gut microbial metabolite UroA as an important cause of CPH. We demonstrate that UroA exerts an excellent anti-CPH effect by suppressing HSC glutaminolysis to lower the IHVR, which highlighted its great potential as a novel therapeutic agent for CPH.

Roles and therapeutic targeting of dendritic cells in liver fibrosis

Liver fibrosis is a common pathological condition marked by excessive accumulation of extracellular matrix proteins, resulting in irreversible cirrhosis and cancer. Dendritic cells (DCs) act as the crucial component of hepatic immunity and are believed to affect fibrosis by regulating the proliferation and differentiation of hepatic stellate cells (HSCs), a key mediator of fibrogenesis, and by interplaying with immune cells in the liver. This review concisely describes the process of fibrogenesis, and the phenotypic and functional characteristics of DCs in the liver. Besides, it focuses on the interaction between DCs and HSCs, T cells, and natural killer (NK) cells, as well as the dual roles of DCs in liver fibrosis, for the sake of exploring the potential of targeting DCs as a therapeutic strategy for the disease.

Differential cell type-specific function of the aryl hydrocarbon receptor and its repressor in diet-induced obesity and fibrosis

OBJECTIVE

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor regulating xenobiotic responses as well as physiological metabolism. Dietary AhR ligands activate the AhR signaling axis, whereas AhR activation is negatively regulated by the AhR repressor (AhRR). While AhR-deficient mice are known to be resistant to diet-induced obesity (DIO), the influence of the AhRR on DIO has not been assessed so far.

METHODS

In this study, we analyzed AhRR-/- mice and mice with a conditional deletion of either AhRR or AhR in myeloid cells under conditions of DIO and after supplementation of dietary AhR ligands. Moreover, macrophage metabolism was assessed using Seahorse Mito Stress Test and ROS assays as well as transcriptomic analysis.

RESULTS

We demonstrate that global AhRR deficiency leads to a robust, but not as profound protection from DIO and hepatosteatosis as AhR deficiency. Under conditions of DIO, AhRR-/- mice did not accumulate TCA cycle intermediates in the circulation in contrast to wild-type (WT) mice, indicating protection from metabolic dysfunction. This effect could be mimicked by dietary supplementation of AhR ligands in WT mice. Because of the predominant expression of the AhRR in myeloid cells, AhRR-deficient macrophages were analyzed for changes in metabolism and showed major metabolic alterations regarding oxidative phosphorylation and mitochondrial activity. Unbiased transcriptomic analysis revealed increased expression of genes involved in de novo lipogenesis and mitochondrial biogenesis. Mice with a genetic deficiency of the AhRR in myeloid cells did not show alterations in weight gain after high fat diet (HFD) but demonstrated ameliorated liver damage compared to control mice. Further, deficiency of the AhR in myeloid cells also did not affect weight gain but led to enhanced liver damage and adipose tissue fibrosis compared to controls.

CONCLUSIONS

AhRR-deficient mice are resistant to diet-induced metabolic syndrome. Although conditional ablation of either the AhR or AhRR in myeloid cells did not recapitulate the phenotype of the global knockout, our findings suggest that enhanced AhR signaling in myeloid cells deficient for AhRR protects from diet-induced liver damage and fibrosis, whereas myeloid cell-specific AhR deficiency is detrimental.

Histologic Features of Mycobacterial Spindle Cell Pseudotumors: A Multi-institutional Clinicopathologic Analysis of 14 Cases

Mycobacterial spindle cell pseudotumors (MSPs) are a rare and diagnostically challenging manifestation of non-tuberculous mycobacterial (NTM) infections. Proper recognition of these pseudotumors is important because they are treatable and benign. In this study, we evaluated the morphologic patterns of MSPs to improve their pathologic identification. Clinical and morphologic features of 14 MSPs were analyzed. Histologic factors evaluated included the architectural growth pattern of spindled or epithelioid macrophages, granulomas and their location within the lesion, neutrophilic microabscesses, multinucleated giant cells, necrosis, and effacement of background tissue. The composition of inflammatory infiltrates, organism density by acid-fast staining, and stromal changes were also assessed. In addition, 8 of 14 cases underwent molecular microbiology identification by a clinical amplicon-sequencing assay for non-tuberculous mycobacteria. MSP sites included 2 bowel, 10 lymph nodes, 1 liver, and 1 extremity. Cases with available clinical history (n=10) all occurred in immunocompromised patients. All demonstrated effacement of normal structures with spindled cells arranged in a storiform or fascicular architectural pattern. In addition, all cases showed lymphocytic inflammation, with prominent concurrent neutrophilic inflammation in 50% (7/14) of cases. Other morphologic findings included foamy histiocytes (64%, 9/14), peripherally situated granulomas (21%, 3/14), and neutrophilic microabscesses (21%, 3/14). All tested cases were positive for NTM by PCR methods. Mycobacterium avium was the most commonly isolated pathogen (6/8). Mycobacterial spindle cell pseudotumors show predominantly spindled morphology that may be mistaken as a neoplasm. Surgical pathologists who evaluate lymph nodes, soft tissue, and gastrointestinal tissues should be aware of this spindled tumefactive phenomenon in the setting of immunocompromised patients. Recognition of key morphologic features of neutrophilic inflammation, peripheral granulomas, or foamy histiocytes within a spindled lesion can help guide the pathologist to a correct diagnosis of an inflammatory process secondary to infection rather than a spindle cell neoplasm. Accurate diagnosis to facilitate appropriate antimicrobial and/or surgical therapy requires a comprehensive evaluation combining clinical, histopathologic, and microbiological findings.

Macrophages and tumor-associated macrophages in the senescent microenvironment: From immunosuppressive TME to targeted tumor therapy

In-depth studies of the tumor microenvironment (TME) have helped to elucidate its cancer-promoting mechanisms and inherent characteristics. Cellular senescence, which acts as a response to injury and can the release of senescence-associated secretory phenotypes (SASPs). These SASPs release various cytokines, chemokines, and growth factors, remodeling the TME. This continual development of a senescent environment could be associated with chronic inflammation and immunosuppressive TME. Additionally, SASPs could influence the phenotype and function of macrophages, leading to the recruitment of tumor-associated macrophages (TAMs). This contributes to tumor proliferation and metastasis in the senescent microenvironment, working in tandem with immune regulation, angiogenesis, and therapeutic resistance. This comprehensive review covers the evolving nature of the senescent microenvironment, macrophages, and TAMs in tumor development. We also explored the links between chronic inflammation, immunosuppressive TME, cellular senescence, and macrophages. Moreover, we compiled various tumor-specific treatment strategies centered on cellular senescence and the current challenges in cellular senescence research. This study aimed to clarify the mechanism of macrophages and the senescent microenvironment in tumor progression and advance the development of targeted tumor therapies.

HIV coinfection exacerbates HBV-induced liver fibrogenesis through a HIF-1α- and TGF-β1-dependent pathway

BACKGROUND & AIMS

Persons with chronic HBV infection coinfected with HIV experience accelerated progression of liver fibrosis compared to those with HBV monoinfection. We aimed to determine whether HIV and its proteins promote HBV-induced liver fibrosis in HIV/HBV-coinfected cell culture models through HIF-1α and TGF-β1 signaling.

METHODS

The HBV-positive supernatant, purified HBV viral particles, HIV-positive supernatant, or HIV viral particles were directly incubated with cell lines or primary hepatocytes, hepatic stellate cells, and macrophages in mono or 3D spheroid coculture models. Cells were incubated with recombinant cytokines and HIV proteins including gp120. HBV sub-genomic constructs were transfected into NTCP-HepG2 cells. We also evaluated the effects of inhibitor of HIF-1α and HIV gp120 in a HBV carrier mouse model that was generated via hydrodynamic injection of the pAAV/HBV1.2 plasmid into the tail vein of wild-type C57BL/6 mice.

RESULTS

We found that HIV and HIV gp120, through engagement with CCR5 and CXCR4 coreceptors, activate AKT and ERK signaling and subsequently upregulate hypoxia-inducible factor-1α (HIF-1α) to increase HBV-induced transforming growth factor-β1 (TGF-β1) and profibrogenic gene expression in hepatocytes and hepatic stellate cells. HIV gp120 exacerbates HBV X protein-mediated HIF-1α expression and liver fibrogenesis, which can be alleviated by inhibiting HIF-1α. Conversely, TGF-β1 upregulates HIF-1α expression and HBV-induced liver fibrogenesis through the SMAD signaling pathway. HIF-1α small-interfering RNA transfection or the HIF-1α inhibitor (acriflavine) blocked HIV-, HBV-, and TGF-β1-induced fibrogenesis.

CONCLUSIONS

Our findings suggest that HIV coinfection exacerbates HBV-induced liver fibrogenesis through enhancement of the positive feedback between HIF-1α and TGF-β1 via CCR5/CXCR4. HIF-1α represents a novel target for antifibrotic therapeutic development in HBV/HIV coinfection.

IMPACT AND IMPLICATIONS

HIV coinfection accelerates the progression of liver fibrosis compared to HBV monoinfection, even among patients with successful suppression of viral load, and there is no sufficient treatment for this disease process. In this study, we found that HIV viral particles and specifically HIV gp120 promote HBV-induced hepatic fibrogenesis via enhancement of the positive feedback between HIF-1α and TGF-β1, which can be ameliorated by inhibition of HIF-1α. These findings suggest that targeting the HIF-1α pathway can reduce liver fibrogenesis in patients with HIV and HBV coinfection.

HIV-1 Structural Proteins or Cell-Signaling Factors? That Is the Question!

The biological activity of structural HIV-1 proteins is not limited to ensuring a productive viral infection but also interferes with cellular homeostasis through intra- and extracellular signaling activation. This interference induces genomic instability, increases the lifespan of the infected cell by inhibiting apoptosis, and subverts cell senescence, resulting in unrestricted cell proliferation. HIV structural proteins are present in a soluble form in the lymphoid tissues and blood of infected individuals, even without active viral replication. The HIV matrix protein p17, the envelope glycoprotein gp120, the transenvelope protein gp41, and the capsid protein p24 interact with immune cells and deregulate the biological activity of the immune system. The biological activity of HIV structural proteins is also demonstrated in endothelial cells and some tumor cell lines, confirming the ability of viral proteins to promote cell proliferation and cancer progression, even in the absence of active viral replication. This review corroborates the hypothesis that HIV structural proteins, by interacting with different cell types, contribute to creating a microenvironment that is favorable to the evolution of cancerous pathologies not classically related to AIDS.

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

Background & Aims

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

Methods

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

Results

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

Conclusions

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

Impact and implications

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

Plasticity, heterogeneity, and multifunctionality of hepatic stellate cells in liver pathophysiology

HSCs, the resident pericytes of the liver, have consistently been at the forefront of liver research due to their crucial roles in various hepatic pathological processes. Prior literature often depicted HSCs in a binary framework, categorizing them as either quiescent or activated. However, recent advances in HSC research, particularly the advent of single-cell RNA-sequencing, have revolutionized our understanding of these cells. This sophisticated technique offers an unparalleled, high-resolution insight into HSC populations, uncovering a spectrum of diversity and functional heterogeneity across various physiological states of the liver, ranging from liver development to the liver aging process. The single-cell RNA-sequencing revelations have also highlighted the intrinsic plasticity of HSCs and underscored their complex roles in a myriad of pathophysiological processes, including liver injury, repair, and carcinogenesis. This review aims to integrate and clarify these recent discoveries, focusing on how the inherent plasticity of HSCs is central to their dynamic roles both in maintaining liver homeostasis and orchestrating responses to liver injury. Future research will clarify whether findings from rodent models can be translated to human livers and guide how these insights are harnessed to develop targeted therapeutic interventions.

Inflammation in Alcohol-Associated Hepatitis: Pathogenesis and Therapeutic Targets

Alcohol-associated hepatitis (AH) is an acute-on-chronic liver injury that occurs in patients with chronic alcohol-associated liver disease (ALD). Patients with severe AH have high short-term mortality and lack effective pharmacologic therapies. Inflammation is believed to be one of the key factors promoting AH progression and has been actively investigated as therapeutic targets over the last several decades, but no effective inflammatory targets have been identified so far. In this review, we discuss how inflammatory cells and the inflammatory mediators produced by these cells contribute to the development and progression of AH, with focus on neutrophils and macrophages. The crosstalk between inflammatory cells and liver nonparenchymal cells in the pathogenesis of AH is elaborated. We also deliberate the application of recent cutting-edge technologies in characterizing liver inflammation in AH. Finally, the potential therapeutic targets of inflammatory mediators for AH are briefly summarized.

Single-cell RNA sequencing reveals the heterogeneity of hepatic non-parenchymal cell responses to chronic PFO5DoDA exposure in male mice

Perfluoroalkyl ether carboxylic acids (PFECA) have emerged as novel alternatives to legacy per- and polyfluoroalkyl substances (PFAS). Existing research has revealed hepatoxicity induced by various PFAS, including PFECA. However, these studies have primarily focused on overall changes in whole liver tissue, particularly in hepatocytes, with the impact of PFAS on diverse liver non-parenchymal cells (NPCs) still inadequately understood. In the present study, we examined the heterogeneous responses of hepatic NPCs following exposure to perfluoro-3,5,7,9,11-pentaoxadodecanoic acid (PFO5DoDA), a type of PFECA, by administering PFO5DoDA (5 μg/L)-contaminated water to male mice for one year. Single-cell RNA sequencing (scRNA-seq) of 15 008 cells from the liver identified 10 distinct NPC populations. Notably, although relative liver weight remained largely unchanged following exposure to 5 μg/L PFO5DoDA, there was an observed increase in proliferating cells, indicating that proliferating NPCs may contribute to the hepatomegaly frequently noted in PFAS-exposed livers. There was also a considerable alteration in the composition of hepatic NPCs. Specifically, the total number of B cells decreased substantially, while many other cells, such as monocytes and macrophages, increased after PFO5DoDA exposure. In addition, interactions among the hepatic NPC populations changed variously after PFO5DoDA exposure. The findings emphasize the heterogeneity in the responses of hepatic NPCs to PFO5DoDA exposure. Taken together, the changes in immune cell populations and their intercellular interactions suggest that PFO5DoDA disrupts immune homeostasis in the liver. These findings offer new insights into the cellular mechanisms of PFAS-induced liver damage.

Diverse potential of secretome from natural killer cells and monocyte-derived macrophages in activating stellate cells

Chronic liver diseases, such as non-alcoholic steatohepatitis (NASH)-induced cirrhosis, are characterized by an increasing accumulation of stressed, damaged, or dying hepatocytes. Hepatocyte damage triggers the activation of resident immune cells, such as Kupffer cells (KC), as well as the recruitment of immune cells from the circulation toward areas of inflammation. After infiltration, monocytes differentiate into monocyte-derived macrophages (MoMF) which are functionally distinct from resident KC. We herein aim to compare the in vitro signatures of polarized macrophages and activated hepatic stellate cells (HSC) with ex vivo-derived disease signatures from human NASH. Furthermore, to shed more light on HSC activation and liver fibrosis progression, we investigate the effects of the secretome from primary human monocytes, macrophages, and NK cells on HSC activation. Interleukin (IL)-4 and IL-13 treatment induced transforming growth factor beta 1 (TGF-β1) secretion by macrophages. However, the supernatant transfer did not induce HSC activation. Interestingly, PMA-activated macrophages showed strong induction of the fibrosis response genes COL10A1 and CTGF, while the supernatant of IL-4/IL-13-treated monocytes induced the upregulation of COL3A1 in HSC. The supernatant of PMA-activated NK cells had the strongest effect on COL10A1 induction in HSC, while IL-15-stimulated NK cells reduced the expression of COL1A1 and CTGF. These data indicate that other factors, aside from the well-known cytokines and chemokines, might potentially be stronger contributors to the activation of HSCs and induction of a fibrotic response, indicating a more diverse and complex role of monocytes, macrophages, and NK cells in liver fibrosis progression.

Dietary glycemic and energy load differentially modulates Schistosoma mansoni-induced granulomatous inflammation and response to antiparasitic chemotherapy

The impact of diet composition and energy content on schistosomiasis evolution and treatment efficacy is still controversial. This study compared the impact of sucrose-rich diet and intermittent fasting on Schistosoma mansoni infection and praziquantel (PZQ)-based chemotherapy response in mice. BALB/c mice were infected with S. mansoni and followed for 15 weeks. The animals were randomized into nine groups receiving high glycemic load (high-sucrose diet - HSD), low caloric load (standard chow alternate-day fasting - ADF), and standard chow ad libitum (AL). Eight weeks after S. mansoni infection, these groups remained untreated or were treated with PZQ (300 mg/kg/day) for 3 days. Our results indicated that parasite load (S. mansoni eggs and parasite DNA levels), granulomatous inflammation (granulomas number and size), and liver microstructural damage (reduction in hepatocytes number, increase in nucleus-cytoplasm ratio, connective stroma expansion and fibrosis) were increased in ADF-treated animals. These animals also showed decreased eggs retention, granulomatous inflammation and collagen accumulation in the small intestine. Conversely, HSD diet and PZQ treatment attenuated all these parameters and stimulated hepatic regenerative response. PZQ also stimulated fibrosis resolution in HSD-treated mice, effect that was limited ADF-exposed mice. Our findings indicate that dietary glycemic and energy load can modulate schistosomiasis progression and the severity of hepatic and intestinal granulomatous inflammation in untreated and PZQ-treated mice. Thus, lower intestinal eggs retention may potentially be linked to worsening liver disease in ADF, while attenuation of hepatic and intestinal granulomatous inflammation is consistent with reduced parasite load in HSD- and PZQ-treated animals.

Recent understanding of the mechanisms of the biological activities of hesperidin and hesperetin and their therapeutic effects on diseases

Flavonoids are natural phytochemicals that have therapeutic effects and act in the prevention of several pathologies. These phytochemicals can be found in lemon, sweet orange, bitter orange, clementine. Hesperidin and hesperetin are citrus flavonoids from the flavanones subclass that have anti-inflammatory, antioxidant, antitumor and antibacterial potential. Preclinical studies and clinical trials demonstrated therapeutical effects of hesperidin and its aglycone hesperetin in various diseases, such as bone diseases, cardiovascular diseases, neurological diseases, respiratory diseases, digestive diseases, urinary tract diseases. This review provides a comprehensive overview of the biological activities of hesperidin and hesperetin, their therapeutic potential in various diseases and their associated molecular mechanisms. This article also discusses future considerations for the clinical applications of hesperidin and hesperetin.

Identification of STAT3 as a biomarker for cellular senescence in liver fibrosis: A bioinformatics and experimental validation study

BACKGROUND

Cellular senescence is associated with a dysregulated inflammatory response, which is an important driver of the development of liver fibrosis (LF). This study aimed to investigate the effect of cellular senescence on LF and identify potential key biomarkers through bioinformatics analysis combined with validation experiments in vivo and in vitro.

METHODS

The Gene Expression Omnibus (GEO) database and GeneCards database were used to download the LF dataset and the aging-related gene set, respectively. Functional enrichment analysis of differential genes was then performed using GO and KEGG. Hub genes were further screened using Cytoscape's cytoHubba. Diagnostic values for hub genes were evaluated with a receiver operating characteristic (ROC) curve. Next, CIBERSORTx was used to estimate immune cell types and ratios. Finally, in vivo and in vitro experiments validated the results of the bioinformatics analysis. Moreover, molecular docking was used to simulate drug-gene interactions.

RESULTS

A total of 44 aging-related differentially expressed genes (AgDEGs) were identified, and enrichment analysis showed that these genes were mainly enriched in inflammatory and immune responses. PPI network analysis identified 6 hub AgDEGs (STAT3, TNF, MMP9, CD44, TGFB1, and TIMP1), and ROC analysis showed that they all have good diagnostic value. Immune infiltration suggested that hub AgDEGs were significantly associated with M1 macrophages or other immune cells. Notably, STAT3 was positively correlated with α-SMA, COL1A1, IL-6 and IL-1β, and was mainly expressed in hepatocytes (HCs). Validation experiments showed that STAT3 expression was upregulated and cellular senescence was increased in LF mice. A co-culture system of HCs and hepatic stellate cells (HSCs) further revealed that inhibiting STAT3 reduced HCs senescence and suppressed HSCs activation. In addition, molecular docking revealed that STAT3 was a potential drug therapy target.

CONCLUSIONS

STAT3 may be involved in HCs senescence and promote HSCs activation, which in turn leads to the development of LF. Our findings suggest that STAT3 could be a potential biomarker for LF.