Lytic cell death in metabolic liver disease

Ferroptosis promotes valproate-induced liver steatosis in vitro and in vivo

Valproic acid (VPA), a common antiepileptic drug, can cause liver steatosis after long-term therapy. However, an impact of ferroptosis on VPA-induced liver steatosis has not been investigated. In the study, treatment with VPA promoted ferroptosis in the livers of mice by elevating ferrous iron (Fe2+) levels derived from the increased absorption by transferrin receptor 1 (TFR1) and the decreased storage by ferritin (FTH1 and FTL), disrupting the redox balance via reduced levels of solute carrier family 7 member 11 (SLC7A11), glutathione (GSH), and glutathione peroxidase 4 (GPX4), and augmenting acyl-CoA synthetase long-chain family member 4 (ACSL4) -mediated lipid peroxide generation, accompanied by enhanced liver steatosis. All the changes were significantly reversed by co-treatment with an iron-chelating agent, deferoxamine mesylate (DFO) and a ferroptosis inhibitor, ferrostatin-1 (Fer-1). Similarly, the increases in Fe2+, TFR1, and ACSL4 levels, as well as the decreases in GSH, GPX4, and ferroportin (FPN) levels, were detected in VPA-treated HepG2 cells. These changes were also attenuated after co-treatment with Fer-1. It demonstrates that ferroptosis promotes VPA-induced liver steatosis through iron overload, inhibition of the GSH-GPX4 axis, and upregulation of ACSL4. It offers a potential therapy targeting ferroptosis for patients with liver steatosis following VPA treatment.

New perspective for pathomechanism and clinical applications of animal toxins: Programmed cell death

Various animal toxins pose a significant threat to human safety, necessitating urgent attention to their treatment and research. The clinical potential of programmed cell death (PCD) is widely regarded as a target for envenomation, given its crucial role in regulating physiological and pathophysiological processes. Current research on animal toxins examines their specific components in pathomechanisms and injuries, as well as their clinical applications. This review explores the relationship between various toxins and several types of PCD, such as apoptosis, necroptosis, autophagy, ferroptosis, and pyroptosis, to provide a reference for future understanding of the pathophysiology of toxins and the development of their potential clinical value.

Isobavachalcone induces hepatotoxicity in zebrafish embryos and HepG2 cells via the System Xc--GSH-GPX4 signaling pathway in ferroptosis response

Isobavachalcone (IBC) is a flavonoid component of the traditional Chinese medicine Psoraleae Fructus, with a range of pharmacological properties. However, IBC causes some hepatotoxicity, and the mechanism of toxicity is unclear. The purpose of this paper was to investigate the possible mechanism of toxicity of IBC on HepG2 cells and zebrafish embryos. The results showed that exposure to IBC increased zebrafish embryo mortality and decreased hatchability. Meanwhile, IBC induced liver injury and increased expression of ALT and AST activity. Further studies showed that IBC caused the increase of ROS and MDA the decrease of CAT, GSH, and GSH-Px; the increase of Fe2+ content; and the changes of ferroptosis related genes (acsl4, gpx4, and xct) and iron storage related genes (tf, fth, and fpn) in zebrafish embryos. Through in vitro verification, it was found that IBC also caused oxidative stress and increased Fe2+ content in HepG2 cells. IBC caused depolarization of mitochondrial membrane potential (MMP) and reduction of mitochondrial ATP, as well as altered expression of ACSl4, SLC7A11, GPX4, and FTH1 proteins. Treatment of HepG2 cells with ferrostatin-1 could reverse the effect of IBC. Targeting the System Xc--GSH-GPX4 pathway of ferroptosis and preventing oxidative stress damage might offer a theoretical foundation for practical therapy and prevention of IBC-induced hepatotoxicity.

Mechanism of PANoptosis in metabolic dysfunction-associated steatotic liver disease

In recent years, the incidence of metabolic dysfunction-associated steatotic liver disease (MASLD) has been steadily rising, emerging as a major chronic liver disease of global concern. The course of MASLD is varied, spanning from MASLD to metabolic dysfunction associated steatohepatitis (MASH). MASH is an important contributor to cirrhosis, which may subsequently lead to hepatocellular carcinoma. It has been found that PANoptosis, an emerging inflammatory programmed cell death (PCD), is involved in the pathogenesis of MASLD and facilitates the development of NASH, eventually resulting in inflammatory fibrosis and hepatocyte death. This paper reviews the latest research progress on PANoptosis and MASLD to understand the mechanism of MASLD and provide new directions for future treatment and drug development.

Ferroptosis is a targetable detrimental factor in metabolic dysfunction-associated steatotic liver disease

There is an unmet clinical need for pharmacologic treatment for metabolic dysfunction-associated steatotic liver disease (MASLD). Hepatocyte cell death is a hallmark of this highly prevalent chronic liver disease, but the dominant type of cell death remains uncertain. Here we report that ferroptosis, an iron-catalyzed mode of regulated cell death, contributes to MASLD. Unsupervised clustering in a cohort of biopsy-proven MASLD patients revealed a subgroup with hepatic ferroptosis signature and lower glutathione peroxidase 4 (GPX4) levels. Likewise, a subgroup with reduced ferroptosis defenses was discerned in public transcriptomics datasets. Four weeks of choline-deficient L-amino acid-defined high-fat diet (CDAHFD) induced MASLD with ferroptosis in mice. Gpx4 overexpression did not affect steatohepatitis, instead CDAHFD protected from morbidity due to hepatocyte-specific Gpx4 knockout. The ferroptosis inhibitor UAMC-3203 attenuated steatosis and alanine aminotransferase in CDAHFD and a second model, i.e., the high-fat high-fructose diet (HFHFD). The effect of monounsaturated and saturated fatty acids supplementation on ferroptosis susceptibility was assessed in human HepG2 cells. Fat-laden HepG2 showed a drop in ferroptosis defenses, increased phosphatidylglycerol with two polyunsaturated fatty acid (PUFA) lipid tails, and sustained ferroptosis sensitivity. In conclusion, this study identified hepatic ferroptosis as a detrimental factor in MASLD patients. Unexpectedly, non-PUFA supplementation to hepatocytes altered lipid bilayer composition to maintain ferroptosis sensitivity. Based on findings in in vivo models, ferroptosis inhibition represents a promising therapeutic target in MASLD.

Lipopolysaccharide-Induced Lysosomal Cell Death Through Reactive Oxygen Species in Rat Liver Cell Clone 9

In sepsis, bacterial components, particularly lipopolysaccharide (LPS), trigger organ injuries such as liver dysfunction. Although sepsis induces hepatocyte damage, the mechanisms underlying sepsis-related hepatic failure remain unclear. In this study, we demonstrated that the LPS-treated rat hepatocyte cell line Clone 9 not only induced reactive oxygen species (ROS) generation and apoptosis but also increased the expression of the autophagy marker proteins LC3-II and p62, and decreased the expression of intact Lamp2A, a lysosomal membrane protein. Additionally, LPS increased lysosomal membrane permeability and galectin-3 puncta formation, and promoted lysosomal alkalization in Clone 9 cells. Pharmacological inhibition of caspase-8 and cathepsin D (CTSD) suppressed the activation of caspase-3 and rescued the viability of LPS-treated Clone 9 cells. Furthermore, LPS induced CTSD release associated with lysosomal leakage and contributed to caspase-8 activation. Pretreatment with the antioxidant N-acetylcysteine (NAC) not only diminished ROS generation and increased the cell survival rate, but also decreased the expression of activated caspase-8 and caspase-3 and increased the protein level of Lamp2A in LPS-treated Clone 9 cells. These results demonstrate that LPS-induced ROS causes lysosomal membrane permeabilization and lysosomal cell death, which may play a crucial role in hepatic failure in sepsis. Our results may facilitate the development of new strategies for sepsis management.

Hepatocyte programmed cell death: the trigger for inflammation and fibrosis in metabolic dysfunction-associated steatohepatitis

By replacing and removing defective or infected cells, programmed cell death (PCD) contributes to homeostasis maintenance and body development, which is ubiquitously present in mammals and can occur at any time. Besides apoptosis, more novel modalities of PCD have been described recently, such as necroptosis, pyroptosis, ferroptosis, and autophagy-dependent cell death. PCD not only regulates multiple physiological processes, but also participates in the pathogenesis of diverse disorders, including metabolic dysfunction-associated steatotic liver disease (MASLD). MASLD is mainly classified into metabolic dysfunction-associated steatotic liver (MASL) and metabolic dysfunction-associated steatohepatitis (MASH), and the latter putatively progresses to cirrhosis and hepatocellular carcinoma. Owing to increased incidence and obscure etiology of MASH, its management still remains a tremendous challenge. Recently, hepatocyte PCD has been attracted much attention as a potent driver of the pathological progression from MASL to MASH, and some pharmacological agents have been proved to exert their salutary effects on MASH partly via the regulation of the activity of hepatocyte PCD. The current review recapitulates the pathogenesis of different modalities of PCD, clarifies the mechanisms underlying how metabolic disorders in MASLD induce hepatocyte PCD and how hepatocyte PCD contributes to inflammatory and fibrotic progression of MASH, discusses several signaling pathways in hepatocytes governing the execution of PCD, and summarizes some potential pharmacological agents for MASH treatment which exert their therapeutic effects partly via the regulation of hepatocyte PCD. These findings indicate that hepatocyte PCD putatively represents a new therapeutic point of intervention for MASH.

The role and mechanism of pyroptosis and potential therapeutic targets in non-alcoholic fatty liver disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) is a clinical pathological syndrome characterized by the excessive accumulation of fat within liver cells, which can progress to end-stage liver disease in severe cases, posing a threat to life. Pyroptosis is a distinct, pro-inflammatory form of cell death, differing from traditional apoptosis. In recent years, there has been growing research interest in the association between pyroptosis and NAFLD, encompassing the mechanisms and functions of pyroptosis in the progression of NAFLD, as well as potential therapeutic targets. Controlled pyroptosis can activate immune cells, eliciting host immune responses to shield the body from harm. However, undue activation of pyroptosis may worsen inflammatory responses, induce cellular or tissue damage, disrupt immune responses, and potentially impact liver function. This review elucidates the involvement of pyroptosis and key molecular players, including NOD-like receptor thermal protein domain associated protein 3(NLRP3) inflammasome, gasdermin D (GSDMD), and the caspase family, in the pathogenesis and progression of NAFLD. It emphasizes the promising prospects of targeting pyroptosis as a therapeutic approach for NAFLD and offers valuable insights into future directions in the field of NAFLD treatment.

Astragaloside IV ameliorates cisplatin-induced liver injury by modulating ferroptosis-dependent pathways

ETHNOPHARMACOLOGICAL RELEVANCE

The use of antineoplastic drugs, such as cisplatin, in clinical practice can cause adverse effects in patients, such as liver injury, which limits their long-term use. Therefore, there is an urgent need to develop alternative therapeutic strategies or drugs to minimize cisplatin-induced liver injury. Huangqi, the root of Astragalus membranaceus, is extensively used in traditional Chinese medicine (TCM) and has been employed in treating diverse liver injuries. Astragalus membranaceus contains several bioactive constituents, including triterpenoid saponins, one of which, astragaloside IV (ASIV), has been reported to have anti-inflammatory and antioxidant stress properties. However, its potential in ameliorating cisplatin-induced liver injury has not been explored.

AIM OF THE STUDY

The objective of this study was to examine the mechanism by which ASIV protects against cisplatin-induced liver injury.

MATERIALS AND METHODS

This study established a model of cisplatin-induced liver injury in mice, followed by treatment with various doses of astragaloside IV (40 mg/kg, 80 mg/kg). In addition, a model of hepatocyte ferroptosis in AML-12 cells was established using RSL3. The mechanism of action of astragaloside IV was investigated using a range of methods, including Western blot assay, qPCR, immunofluorescence, histochemistry, molecular docking, and high-content imaging system.

RESULTS

The findings suggested a significant improvement in hepatic injury, inflammation and oxidative stress phenotypes with the administration of ASIV. Furthermore, network pharmacological analyses provided evidence that a major pathway for ASIV to attenuate cisplatin-induced hepatic injury entailed the cell death cascade pathway. It was observed that ASIV effectively inhibited ferroptosis both in vivo and in vitro. Subsequent experimental outcomes provided further validation of ASIV's ability to hinder ferroptosis through the inhibition of PPARα/FSP1 signaling pathway. The current findings suggest that ASIV could function as a promising phytotherapy composition to alleviate cisplatin-induced liver injury.

CONCLUSIONS

The current findings suggest that astragaloside IV could function as a promising phytotherapy composition to alleviate cisplatin-induced liver injury.

Esculin inhibits hepatic stellate cell activation and CCl4-induced liver fibrosis by activating the Nrf2/GPX4 signaling pathway

BACKGROUND

Liver fibrosis (LF) is a pathological process of the liver that threatens human health. Currently, effective treatments are still lacking. Esculin, a prominent constituent found in the Fraxinus rhynchophylla. (bark), Aesculus hippocastanum. (bark), and Cichorium intybus. (herb), has been shown to possess significant anti-inflammatory, antioxidant, and antibacterial properties. However, to date, there have been no studies investigating its potential efficacy in the treatment of LF.

OBJECTIVE

The study aims to investigate the therapeutic effect of esculin on LF and elucidate its potential molecular mechanism.

METHODS

Carbon tetrachloride (CCl4) was injected intraperitoneally to induce LF in mice, and transforming growth factor β1 (TGF-β1) was injected to induce LX-2 cells to investigate the improvement effect of esculin on LF. Kit, histopathological staining, immunohistochemistry (IHC), immunofluorescence (IF), polymerase chain reaction (PCR), and western blot (WB) were used to detect the expression of fiber markers and nuclear factor erythroid 2-related factor 2 (Nrf2)/glutathione peroxidase 4 (GPX4) signaling pathway in liver tissue and LX-2 cells. Finally, molecular docking, cellular thermal shift assay (CETSA), and drug affinity responsive target stability (DARTS) were used to verify the targeting between Nrf2 and esculin.

RESULTS

Esculin significantly inhibited CCl4-induced hepatic fibrosis and inflammation in mice. This was evidenced by the improvement of liver function indexes, fibrosis indicators, and histopathology. Additionally, esculin treatment prominently reduced the levels of pro-inflammatory factors, oxidative stress, and liver Fe2+ in CCl4-induced mice. In vitro studies also showed that esculin treatment significantly inhibited TGF-β1-induced LX-2 cell activation and decreased alpha-smooth muscle actin (α-SMA) and collagen I expression. Mechanism experiments proved that esculin can activate the Nrf2/GPX4 signaling pathway and inhibit liver ferroptosis. However, when LX-2 cells were treated with the Nrf2 inhibitor (ML385), the therapeutic effect of esculin significantly decreased.

CONCLUSION

This study is the first to demonstrate that esculin is a potential natural active ingredient in the treatment of LF, which can inhibit the activation of hepatic stellate cells (HSC) and improve LF. Its therapeutic effect is related to the activation of the Nrf2/GPX4 signaling pathway.

FAdV-4-induced ferroptosis affects fat metabolism in LMH cells

Ferroptosis is a form of controlled cell death that was first described relatively recently and that is dependent on the formation and accumulation of lipid free radicals through an iron-mediated mechanism. A growing body of evidence supports the close relationship between pathogenic infections and ferroptotic cell death, particularly for viral infections. Ferroptosis is also closely tied to the pathogenic development of hepatic steatosis and other forms of liver disease. Fowl adenovirus serotype 4 (FAdV-4) is a hepatotropic aviadenovirus causing hydropericardium syndrome (HPS) that is capable of impacting fat metabolism. However, it remains uncertain as to what role, if any, ferroptotic death plays in the context of FAdV-4 infection. Here, FAdV-4 was found to promote ferroptosis via the p53-SLC7A11-GPX4 axis, while ferrostain-1 was capable of inhibiting this FAdV-4-mediated ferroptotic death through marked reductions in lipid peroxidation. The incidence of FAdV-4-induced fatty liver was also found to be associated with the activation of ferroptotic activity. Together, these results offer novel insights regarding potential approaches to treating HPS.

Necroptosis induced by ruthenium (II) complexes as mitochondrial disruptors

Inducing necroptosis in cancer cells has emerged as an effective strategy to overcome drug resistance. However, while organic small molecules have been extensively studied for this purpose, metal-based compounds have received relatively little attention as triggers of necroptosis. The development of ruthenium (II) hybrid compounds, particularly those containing triazene (Ru-TRZ), highlights a novel avenue for modulating necroptotic cell death. Here we show that incorporating a methyltriazene moiety, a known alkylating warhead, confers superior mitochondrial-targeting properties and enhances cell death compared to amide-containing counterparts. Ru-hybrid TRZ2 exhibits also antitumor efficacy against in vivo drug-resistant cancer cells. Mechanistically, we demonstrate that Ru-TRZ hybrids induce apoptosis. In addition, by activating downstream RIPK3-driven cell death, TRZ2 proficiently restrains normal mitochondrial function and activity, leading to cancer cell necroptosis. Finally, TRZ2 synergizes anti-proliferative activity and cell death effects induced by conventional drugs. In conclusion, Ru-TRZ2 stands as a promising ruthenium-based chemotherapeutic agent inducing necroptosis in drug resistant cancer cells.

Mesenchymal stromal cell-derived extracellular vesicles therapy openings new translational challenges in immunomodulating acute liver inflammation

Inflammation plays a critical role in conditions such as acute liver failure, acute-on-chronic liver failure, and ischemia-reperfusion-induced liver injury. Various pathogenic pathways contribute to liver inflammation, involving inflammatory polarization of macrophages and Küpffer cells, neutrophil infiltration, dysregulation of T cell subsets, oxidative stress, and activation of hepatic stellate cells. While mesenchymal stromal cells (MSCs) have demonstrated beneficial properties, their clinical translation is limited by their cellular nature. However, MSC-derived extracellular vesicles (MSC-EVs) have emerged as a promising cell-free therapeutic approach for immunomodulation. MSC-EVs naturally mirror their parental cell properties, overcoming the limitations associated with the use of MSCs. In vitro and in vivo preclinical studies have demonstrated that MSC-EVs replicate the beneficial effects of MSCs in liver injury. This includes the reduction of cell death and oxidative stress, improvement of hepatocyte function, induction of immunomodulatory effects, and mitigation of cytokine storm. Nevertheless, MSC-EVs face challenges regarding the necessity of defining consistent isolation methods, optimizing MSCs culture conditions, and establishing quality control measures for EV characterization and functional assessment. By establishing standardized protocols, guidelines, and affordable cost mass production, clinicians and researchers will have a solid foundation to conduct further studies, validate the therapeutic efficacy of MSC-EVs, and ultimately pave the way for their clinical implementation in acute liver injury.

Elucidating cuproptosis in metabolic dysfunction-associated steatotic liver disease

Emerging research into metabolic dysfunction-associated steatotic liver disease (MASLD) up until January 2024 has highlighted the critical role of cuproptosis, a unique cell death mechanism triggered by copper overload, in the disease's development. This connection offers new insights into MASLD's complex pathogenesis, pointing to copper accumulation as a key factor that disrupts lipid metabolism and insulin sensitivity. The identification of cuproptosis as a significant contributor to MASLD underscores the potential for targeting copper-mediated pathways for novel therapeutic approaches. This promising avenue suggests that managing copper levels could mitigate MASLD progression, offering a fresh perspective on treatment strategies. Further investigations into how cuproptosis influences MASLD are essential for unraveling the detailed mechanisms at play and for identifying effective interventions. The focus on copper's role in liver health opens up the possibility of developing targeted therapies that address the underlying causes of MASLD, moving beyond symptomatic treatment to tackle the root of the problem. The exploration of cuproptosis in the context of MASLD exemplifies the importance of understanding metal homeostasis in metabolic diseases and represents a significant step forward in the quest for more effective treatments. This research direction lights path for innovative MASLD management and reversal.

Crosstalk between cancer-associated fibroblasts and regulated cell death in tumors: insights into apoptosis, autophagy, ferroptosis, and pyroptosis

Cancer-associated fibroblasts (CAFs), the main stromal component of the tumor microenvironment (TME), play multifaceted roles in cancer progression through paracrine signaling, exosome transfer, and cell interactions. Attractively, recent evidence indicates that CAFs can modulate various forms of regulated cell death (RCD) in adjacent tumor cells, thus involving cancer proliferation, therapy resistance, and immune exclusion. Here, we present a brief introduction to CAFs and basic knowledge of RCD, including apoptosis, autophagy, ferroptosis, and pyroptosis. In addition, we further summarize the different types of RCD in tumors that are mediated by CAFs, as well as the effects of these modes of RCD on CAFs. This review will deepen our understanding of the interactions between CAFs and RCD and might offer novel therapeutic avenues for future cancer treatments.

Updated mechanisms of MASLD pathogenesis

Metabolic dysfunction-associated steatotic liver disease (MASLD) has garnered considerable attention globally. Changing lifestyles, over-nutrition, and physical inactivity have promoted its development. MASLD is typically accompanied by obesity and is strongly linked to metabolic syndromes. Given that MASLD prevalence is on the rise, there is an urgent need to elucidate its pathogenesis. Hepatic lipid accumulation generally triggers lipotoxicity and induces MASLD or progress to metabolic dysfunction-associated steatohepatitis (MASH) by mediating endoplasmic reticulum stress, oxidative stress, organelle dysfunction, and ferroptosis. Recently, significant attention has been directed towards exploring the role of gut microbial dysbiosis in the development of MASLD, offering a novel therapeutic target for MASLD. Considering that there are no recognized pharmacological therapies due to the diversity of mechanisms involved in MASLD and the difficulty associated with undertaking clinical trials, potential targets in MASLD remain elusive. Thus, this article aimed to summarize and evaluate the prominent roles of lipotoxicity, ferroptosis, and gut microbes in the development of MASLD and the mechanisms underlying their effects. Furthermore, existing advances and challenges in the treatment of MASLD were outlined.

Naringenin alleviates liver fibrosis by triggering autophagy-dependent ferroptosis in hepatic stellate cells

Inhibition of activated hepatic stellate cells (HSCs) is a promising approach for treating liver fibrosis, and the ferroptosis has emerged as a pivotal mechanism to achieve this inhibition. The effects of naringenin, a flavonoid with anti-inflammatory properties, have not been thoroughly examined in liver fibrosis. Therefore, we used cholestasis model to study the effect of naringenin on liver fibrosis. Our findings demonstrated a significant exacerbation of liver tissue damage and fibrosis in mice subjected to bile duct ligation (BDL), accompanied by a substantial upregulation of fibrogenesis-related gene expression. Notably, naringenin administration markedly alleviated liver injury and fibrosis in these mice. Furthermore, naringenin exhibited inhibitory effects on the activation of HSCs, concurrently inducing ferroptosis. Importantly, naringenin significantly increased autophagic activity in HSCs. This effect was counteracted by co-administration of the autophagy inhibitor 3-MA, leading to a notable reduction in naringenin-induced HSC ferroptosis. In BDL model mice, naringenin demonstrated a mitigating effect on liver fibrosis, suggesting a potential correlation with naringenin-induced ferroptosis of HSCs. These results provide novel insights into the molecular mechanisms of naringenin-induced ferroptosis and highlight autophagy-dependent ferroptosis as a promising therapeutic strategy for liver fibrosis.

Necroptosis contributes to non-alcoholic fatty liver disease pathoetiology with promising diagnostic and therapeutic functions

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent type of chronic liver disease. However, the disease is underappreciated as a remarkable chronic disorder as there are rare managing strategies. Several studies have focused on determining NAFLD-caused hepatocyte death to elucidate the disease pathoetiology and suggest functional therapeutic and diagnostic options. Pyroptosis, ferroptosis, and necroptosis are the main subtypes of non-apoptotic regulated cell deaths (RCDs), each of which represents particular characteristics. Considering the complexity of the findings, the present study aimed to review these types of RCDs and their contribution to NAFLD progression, and subsequently discuss in detail the role of necroptosis in the pathoetiology, diagnosis, and treatment of the disease. The study revealed that necroptosis is involved in the occurrence of NAFLD and its progression towards steatohepatitis and cancer, hence it has potential in diagnostic and therapeutic approaches. Nevertheless, further studies are necessary.

Emerging role of ferroptosis in metabolic dysfunction-associated steatotic liver disease: revisiting hepatic lipid peroxidation

Metabolic dysfunction-associated steatohepatitis (MASH) is characterised by cell death of parenchymal liver cells which interact with their microenvironment to drive disease activity and liver fibrosis. The identification of the major death type could pave the way towards pharmacotherapy for MASH. To date, increasing evidence suggest a type of regulated cell death, named ferroptosis, which occurs through iron-catalysed peroxidation of polyunsaturated fatty acids (PUFA) in membrane phospholipids. Lipid peroxidation enjoys renewed interest in the light of ferroptosis, as druggable target in MASH. This review recapitulates the molecular mechanisms of ferroptosis in liver physiology, evidence for ferroptosis in human MASH and critically appraises the results of ferroptosis targeting in preclinical MASH models. Rewiring of redox, iron and PUFA metabolism in MASH creates a proferroptotic environment involved in MASH-related hepatocellular carcinoma (HCC) development. Ferroptosis induction might be a promising novel approach to eradicate HCC, while its inhibition might ameliorate MASH disease progression.

NK-cell-elicited gasdermin-D-dependent hepatocyte pyroptosis induces neutrophil extracellular traps that facilitate HBV-related acute-on-chronic liver failure

BACKGROUND AND AIMS

HBV infection is a major etiology of acute-on-chronic liver failure (ACLF). At present, the pattern and regulation of hepatocyte death during HBV-ACLF progression are still undefined. Evaluating the mode of cell death and its inducers will provide new insights for developing therapeutic strategies targeting cell death. In this study, we aimed to elucidate whether and how immune landscapes trigger hepatocyte death and lead to the progression of HBV-related ACLF.

APPROACH AND RESULTS

We identified that pyroptosis represented the main cell death pattern in the liver of patients with HBV-related ACLF. Deficiency of MHC-I in HBV-reactivated hepatocytes activated cytotoxic NK cells, which in turn operated in a perforin/granzyme-dependent manner to trigger GSDMD/caspase-8-dependent pyroptosis of hepatocytes. Neutrophils selectively accumulated in the pyroptotic liver, and HMGB1 derived from the pyroptotic liver constituted an important factor triggering the generation of pathogenic extracellular traps in neutrophils (NETs). Clinically, elevated plasma levels of myeloperoxidase-DNA complexes were a promising prognostic biomarker for HBV-related ACLF. More importantly, targeting GSDMD pyroptosis-HMGB1 release in the liver abrogates NETs that intercept the development of HBV-related ACLF.

CONCLUSIONS

Studying the mechanisms that selectively modulate GSDMD-dependent pyroptosis, as well as its immune landscapes, will provide a novel strategy for restoring the liver function of patients with HBV-related ACLF.

Poria cocos polysaccharides improve alcoholic liver disease by interfering with ferroptosis through NRF2 regulation

The active ingredient in Poria cocos, a parasitic plant belonging to the family Polyporaceae, is Poria cocos polysaccharide (PCP). PCP exhibits liver protection and anti-inflammatory effects, although its effect on alcoholic liver disease (ALD) remains unstudied. This study investigated the mechanism of PCP in improving ALD by regulating the Nrf2 signaling pathway. After daily intragastric administration of high-grade liquor for 4 hours, each drug group received PCPs or the ferroptosis inhibitor ferrostatin-1. The Nrf2 inhibitor ML385 (100 mg/kg/day) group was intraperitoneally injected, after which PCP (100 mg/kg/day) was administered by gavage. Samples were collected after 6 weeks for liver function and blood lipid analysis using an automatic biochemical analyzer. In the alcoholic liver injury cell model established with 150 mM alcohol, the drug group was pretreated with PCP, Fer-1, and ML385, and subsequent results were analyzed. The results revealed that PCP intervention significantly reduced liver function and blood lipid levels in alcohol-fed rats, along with decreased lipid deposition. PCP notably enhanced Nrf2 signaling expression, regulated oxidative stress levels, inhibited NF-κβ, and its downstream inflammatory signaling pathways. Furthermore, PCP upregulated FTH1 protein expression and reduced intracellular Fe2+, suggesting an improvement in ferroptosis. In vitro studies yielded similar results, indicating that PCP can reduce intracellular ferroptosis by regulating oxidative stress and improve alcoholic liver injury by inhibiting the production of inflammatory factors.

Mesenchymal stem cells and ferroptosis: Clinical opportunities and challenges

Objective

This review discusses recent experimental and clinical findings related to ferroptosis, with a focus on the role of MSCs. Therapeutic efficacy and current applications of MSC-based ferroptosis therapies are also discussed.

Background

Ferroptosis is a type of programmed cell death that differs from apoptosis, necrosis, and autophagy; it involves iron metabolism and is related to the pathogenesis of many diseases, such as Parkinson's disease, cancers, and liver diseases. In recent years, the use of mesenchymal stem cells (MSCs) and MSC-derived exosomes has become a trend in cell-free therapies. MSCs are a heterogeneous cell population isolated from a diverse range of human tissues that exhibit immunomodulatory functions, regulate cell growth, and repair damaged tissues. In addition, accumulating evidence indicates that MSC-derived exosomes play an important role, mainly by carrying a variety of bioactive substances that affect recipient cells. The potential mechanism by which MSC-derived exosomes mediate the effects of MSCs on ferroptosis has been previously demonstrated. This review provides the first overview of the current knowledge on ferroptosis, MSCs, and MSC-derived exosomes and highlights the potential application of MSCs exosomes in the treatment of ferroptotic conditions. It summarizes their mechanisms of action and techniques for enhancing MSC functionality. Results obtained from a large number of experimental studies revealed that both local and systemic administration of MSCs effectively suppressed ferroptosis in injured hepatocytes, neurons, cardiomyocytes, and nucleus pulposus cells and promoted the survival and regeneration of injured organs.

Methods

We reviewed the role of ferroptosis in related tissues and organs, focusing on its characteristics in different diseases. Additionally, the effects of MSCs and MSC-derived exosomes on ferroptosis-related pathways in various organs were reviewed, and the mechanism of action was elucidated. MSCs were shown to improve the disease course by regulating ferroptosis.

Iron, Oxidative Stress, and Metabolic Dysfunction-Associated Steatotic Liver Disease

Excess free iron is a substrate for the formation of reactive oxygen species (ROS), thereby augmenting oxidative stress. Oxidative stress is a well-established cause of organ damage in the liver, the main site of iron storage. Ferroptosis, an iron-dependent mechanism of regulated cell death, has recently been gaining attention in the development of organ damage and the progression of liver disease. We therefore summarize the main mechanisms of iron metabolism, its close connection to oxidative stress and ferroptosis, and its particular relevance to disease mechanisms in metabolic-dysfunction-associated fatty liver disease and potential targets for therapy from a clinical perspective.

Salvianolic acid B attenuates liver fibrosis by targeting Ecm1 and inhibiting hepatocyte ferroptosis

Hepatocyte ferroptosis promotes the pathogenesis and progression of liver fibrosis. Salvianolic acid B (Sal B) exerts antifibrotic effects. However, the pharmacological mechanism and target has not yet been fully elucidated. In this study, liver fibrosis was induced by CCl4 in wild-type mice and hepatocyte-specific extracellular matrix protein 1 (Ecm1)-deficient mice, which were separately treated with Sal B, ferrostatin-1, sorafenib or cilengitide. Erastin- or CCl4-induced hepatocyte ferroptosis models with or without Ecm1 gene knockdown were evaluated in vitro. Subsequently, the interaction between Ecm1 and xCT and the binding kinetics of Sal B and Ecm1 were determined. We found that Sal B significantly attenuated liver fibrosis in CCl4-induced mice. Ecm1 deletion in hepatocytes abolished the antifibrotic effect of Sal B. Mechanistically, Sal B protected against hepatocyte ferroptosis by upregulating Ecm1. Further research revealed that Ecm1 as a direct target for treating liver fibrosis with Sal B. Interestingly, Ecm1 interacted with xCT to regulate hepatocyte ferroptosis. Hepatocyte ferroptosis in vitro was significantly attenuated by Sal B treatment, which was abrogated after knockdown of Ecm1 in LO2 cells. Therefore, Sal B alleviates liver fibrosis in mice by targeting up-regulation of Ecm1 and inhibiting hepatocyte ferroptosis. The interaction between Ecm1 and xCT regulates hepatocyte ferroptosis.

Calenduloside E ameliorates non-alcoholic fatty liver disease via modulating a pyroptosis-dependent pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Non-alcoholic fatty liver disease (NAFLD) is a prevalent chronic liver condition that can have multiple underlying causes. There are no satisfactory chemical or biological drugs for the treatment of NAFLD. Longyasongmu, the bark and root of Aralia elata (Miq.) Seem, is used extensively in traditional Chinese medicine (TCM) and has been used in treating diverse liver diseases including NAFLD. Based on Aralia elata (Miq.) Seem as the main ingredient, Longya Gantai Capsules have been approved for use in China for the treatment of acute hepatitis and chronic hepatitis. Calenduloside E (CE), a natural pentacyclic triterpenoid saponin, is a significant component of saponin isolated from the bark and root of Aralia elata (Miq.) Seem. However, the role and mechanism of anti-NAFLD effects of CE is still unclear.

AIM OF THE STUDY

The objective of this study was to examine the potential mechanisms underlying the protective effect of CE on NAFLD.

MATERIALS AND METHODS

In this study, an NAFLD model was established by Western diet in apoE-/- mice, followed by treatment with various doses of CE (5 mg/kg, 10 mg/kg). The anti-NAFLD effect of CE was assessed by the liver injury, lipid accumulation, inflammation, and pro-fibrotic phenotype. The mechanism of CE in ameliorating NAFLD was studied through transcriptome sequencing (RNA-seq). In vitro, the mouse hepatocytes (AML-12) were stimulated in lipid mixtures with CE and performed the exploration and validation of the relevant pathways using Western blot, immunofluorescence, etc. RESULTS: The findings revealed a significant improvement in liver injury, lipid accumulation, inflammation, and pro-fibrotic phenotype upon CE administration. Furthermore, RNAseq analysis indicated that the primary pathway through which CE alleviates NAFLD involves pyroptosis-related inflammatory cascade pathways. Furthermore, it was observed that CE effectively suppressed inflammasome-mediated pyroptosis both in vivo and in vitro. Remarkably, the functional enrichment analysis of RNA-seq data revealed that the PI3K-Akt signaling pathway is the primarily Signaling transduction pathway modulated by CE treatment. Subsequent experimental outcomes provided further validation of CE's ability to hinder inflammasome-mediated pyroptosis through the inhibition of PI3K/AKT/NF-κB signaling pathway.

CONCLUSIONS

These findings present a novel pharmacological role of CE in exerting anti-NAFLD effects by inhibiting pyroptosis signaling pathways.

cGAS-STING, inflammasomes and pyroptosis: an overview of crosstalk mechanism of activation and regulation

BACKGROUND

Intracellular DNA-sensing pathway cGAS-STING, inflammasomes and pyroptosis act as critical natural immune signaling axes for microbial infection, chronic inflammation, cancer progression and organ degeneration, but the mechanism and regulation of the crosstalk network remain unclear. Cellular stress disrupts mitochondrial homeostasis, facilitates the opening of mitochondrial permeability transition pore and the leakage of mitochondrial DNA to cell membrane, triggers inflammatory responses by activating cGAS-STING signaling, and subsequently induces inflammasomes activation and the onset of pyroptosis. Meanwhile, the inflammasome-associated protein caspase-1, Gasdermin D, the CARD domain of ASC and the potassium channel are involved in regulating cGAS-STING pathway. Importantly, this crosstalk network has a cascade amplification effect that exacerbates the immuno-inflammatory response, worsening the pathological process of inflammatory and autoimmune diseases. Given the importance of this crosstalk network of cGAS-STING, inflammasomes and pyroptosis in the regulation of innate immunity, it is emerging as a new avenue to explore the mechanisms of multiple disease pathogenesis. Therefore, efforts to define strategies to selectively modulate cGAS-STING, inflammasomes and pyroptosis in different disease settings have been or are ongoing. In this review, we will describe how this mechanistic understanding is driving possible therapeutics targeting this crosstalk network, focusing on the interacting or regulatory proteins, pathways, and a regulatory mitochondrial hub between cGAS-STING, inflammasomes, and pyroptosis.

SHORT CONCLUSION

This review aims to provide insight into the critical roles and regulatory mechanisms of the crosstalk network of cGAS-STING, inflammasomes and pyroptosis, and to highlight some promising directions for future research and intervention.

Efferocytosis in liver disease

The process of dead cell clearance by phagocytic cells, called efferocytosis, prevents inflammatory cell necrosis and promotes resolution and repair. Defective efferocytosis contributes to the progression of numerous diseases in which cell death is prominent, including liver disease. Many gaps remain in our understanding of how hepatic macrophages carry out efferocytosis and how this process goes awry in various types of liver diseases. Thus far, studies have suggested that, upon liver injury, liver-resident Kupffer cells and infiltrating monocyte-derived macrophages clear dead cells, limit inflammation, and, through macrophage reprogramming, repair liver damage. However, in unusual settings, efferocytosis can promote liver disease. In this review, we will focus on efferocytosis in various types of acute and chronic liver diseases, including metabolic dysfunction-associated steatohepatitis. Understanding the mechanisms and consequences of efferocytosis by hepatic macrophages has the potential to shed new light on liver disease pathophysiology and to guide new treatment strategies to prevent disease progression.

The intersection between alcohol-related liver disease and nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) and alcohol-related liver disease (ALD) are the leading causes of chronic liver disease worldwide. NAFLD and ALD share pathophysiological, histological and genetic features and both alcohol and metabolic dysfunction coexist as aetiological factors in many patients with hepatic steatosis. A diagnosis of NAFLD requires the exclusion of significant alcohol consumption and other causes of liver disease. However, data suggest that significant alcohol consumption is often under-reported in patients classified as having NAFLD and that alcohol and metabolic factors interact to exacerbate the progression of liver disease. In this Review, we analyse existing data on the interaction between alcohol consumption and metabolic syndrome as well as the overlapping features and differences in the pathogenesis of ALD and NAFLD. We also discuss the clinical implications of the coexistence of alcohol consumption, of any degree, in patients with evidence of metabolic derangement as well as the use of alcohol biomarkers to detect alcohol intake. Finally, we summarize the evolving nomenclature of fatty liver disease and describe a recent proposal to classify patients at the intersection of NAFLD and ALD. We propose that, regardless of the presumed aetiology, patients with fatty liver disease should be evaluated for both metabolic syndrome and alcohol consumption to enable better prognostication and a personalized medicine approach.

Hepatic stellate cells activate and avoid death under necroptosis stimuli: Hepatic fibrosis during necroptosis

BACKGROUND AND AIM

Necroptosis is an emerging cell death pathway that allows cells to undergo "cellular suicide" in a caspase-independent manner. We investigated the fate of hepatic stellate cells (HSCs) under necroptotic stimuli.

METHODS AND RESULTS

The RNA level of mixed lineage kinase domain-like protein (MLKL) is higher in patients with non-alcoholic fatty liver disease than in healthy controls. Hepatic fibrosis was significantly lower in MLKL-KO bile duct ligation (KO-BDL) mice than in wild-type-BDL mice. Necroptotic stimuli caused the death of HT-29 and U937 cells. However, necroptotic stimuli activate HSCs instead of inducing cell death. MLKL inhibitors attenuated fibrogenic changes in HSCs during necroptosis. Unlike HT-29 and U937 cells, MLKL phosphorylation and oligomerization were not observed during necroptosis in HSCs. RNA sequencing showed that NF-κB signaling-related genes were upregulated in HSCs following necroptotic stimulation. Necroptotic stimuli in HSCs increased the nuclear expression of NF-κB, which decreased after MLKL inhibitor treatment. Induction of necroptosis in HSCs led to autophagosome activation and formation, which were attenuated by MLKL inhibitor treatment.

CONCLUSION

HSCs avoid necroptosis due to the absence of MLKL phosphorylation and oligomerization and are activated through autophagosome and NF-κB pathways.

Optimization of preparation method of hepatoprotective active components from Coreopsis tinctoria Nutt. and its action mechanism in vivo

Capitula of Coreopsis tinctoria are widely used as a flower tea with great health benefits due to rich content of flavonoids and phenolic acids. The hepatoprotective effect of C. tinctoria and its bioactive basis have seldom been investigated until now. In the present study, capitula of C. tinctoria were extracted with a method optimized by response surface methodology (RSM) and BoxBehnken design (BBD) and further purified by macroporous resin HPD-300 to obtain a fraction (CE) enriched with flavonoids and phenolic acids. The contents of the four most abundant compounds, isookanin-7-O-β-d-glucoside (1), quercetigetin-7-O-β-d-glucoside (2), okanin (3), and marein (4), were determined by HPLC as 9.98, 5.21, 41.78 and 1.85 mg/g, respectively. Seventy-four compounds including fifity-five flavonoids, fifteen organic acids (twelve of them were phenolic compounds), and three coumarins were tentatively identified in CE by LC-HRMS/MS. In vivo hepatoprotective effect and potential mechanism of CE were studied with a high-fat diet-induced NASH mouse model. CE administration decreased the amount of weight gain, hepatic lipid, and sequentially improved dyslipidemia, inflammation, oxidative stress, and IR in HFD-fed mice. Molecular data revealed that CE inhibited hepatic inflammation by reducing NFκB/iNOS/COX-2/NLRP3/MAPK in the liver tissues and ameliorated oxidative stress by activating the Nrf2/HO-1 pathway. Modulation of inflammation and oxidative stress with CE may represent a promising target for the treatment of NAFLD and provide insight into the mechanism by which CE protects against obesity.

ROS/RNS as molecular signatures of chronic liver diseases

The liver can succumb to oxidant damage during the development of chronic liver diseases. Despite their physiological relevance to hepatic homeostasis, excessive reactive oxygen/nitrogen species (ROS/RNS) production under pathological conditions is detrimental to all liver constituents. Chronic oxidative stress coupled to unresolved inflammation sets in motion the activation of profibrogenic hepatic stellate cells (HSCs) and later pathogenesis of liver fibrosis, cirrhosis, and liver cancer. The liver antioxidant and repair systems, along with autophagic and ferroptotic machineries, are implicated in the onset and trajectory of disease development. In this review, we discuss the ROS/RNS-related mechanisms underlying liver fibrosis of distinct etiologies and highlight preclinical and clinical trials of antifibrotic therapies premised on remediating oxidative/nitrosative stress in hepatocytes or targeting HSC activation.

Identification of pyroptosis-related genes in NASH based on bioinformatic analysis

The objective of this research was to investigate whether or if there is a connection between genes associated with pyroptosis and novel approaches to the diagnosis and treatment of NASH. The mRNA expression patterns of the gene expression dataset GSE135251 integrated (GEO) database were analyzed, and a total of 60 genes related to scorch death were extracted and included in the PubMed database. Methods from the field of bioinformatics were utilized to investigate the degrees to which differentially expressed genes and pyroptosis-related genes differed between NASH patients and healthy controls. As a result of this, the Centre for Genetic Research has now come around to accepting enrichment and PPI interaction analyses. GSE89632 and NASH models were evaluated, trained, qualified, and validated by 18 of the links between the expression of hub genes. PLCG1 expression raised NASH in the progress of the disease. PLCG1 expression levels were then validated by Western Blot and qRT-PCR in FFA-induced HepG2 cells and mouse liver tissues. An analysis of mRNA expression of cleaved-caspase 3, GSDMD, and GSDME in NASH models. In addition, the PLCG1based diagnostic model successfully discriminated NASH from normal samples. Collectively, our results imply that PLCG1 is significantly associated with NASH and may be a biomarker for pyroptosis-related disease.

Intrahepatic Cholangiocarcinoma and Hepatocellular Carcinoma: Real-life Data on Liver Disease, Treatment and Prognosis

Background and Aims

Hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA) have common features and differences. This real-life study investigated their characteristics, treatment modalities, and prognoses.

Methods

This retrospective comparative study was performed in 1,075 patients seen at one tertiary center between January 2008 and December 2020. Overall survival (OS) was estimated by the Kaplan-Meier method. Subclassification of iCCAs after histological and radiological review, and molecular profiling was performed.

Results

HCCs patients were more likely to have early-stage disease than iCCA patients. iCCA patients were more likely to be female, especially those patients without cirrhosis (43% vs. 17%). Cirrhosis was prominent among HCC patients (89% vs. 34%), but no difference in underlying liver disease among cirrhotic patients was found. OS of HCC patients was 18.4 (95% CI: 6.4, 48.3) months, that of iCCA patients was 7.0 (95% CI: 3.4, 20.1) months. OS of Barcelona Clinic Liver Cancer C HCC patients was 7.8 (95% CI: 4.3, 14.2) months, that of advanced/metastatic iCCA patients was 8.5 (95% CI: 5.7, 12.3) months. In patients treated with sorafenib, OS was longer in HCC patients who received subsequent tyrosine kinase inhibitor therapies. No significant OS difference was found between iCCA patients with and without cirrhosis or according to histological subtype. A targetable molecular alteration was detected in 50% of the iCCA patients.

Conclusions

In this French series, cirrhosis was common in iCCA, which showed etiological factors comparable to those of HCC, implying a distinct oncogenic pathway. Both entities had a dismal prognosis at advanced stages. However, systemic therapies sequencing in HCC and molecular profiling in iCCA offer new insights.

Inflammatory signaling in NASH driven by hepatocyte mitochondrial dysfunctions

Liver steatosis, inflammation, and variable degrees of fibrosis are the pathological manifestations of nonalcoholic steatohepatitis (NASH), an aggressive presentation of the most prevalent chronic liver disease in the Western world known as nonalcoholic fatty liver (NAFL). Mitochondrial hepatocyte dysfunction is a primary event that triggers inflammation, affecting Kupffer and hepatic stellate cell behaviour. Here, we consider the role of impaired mitochondrial function caused by lipotoxicity during oxidative stress in hepatocytes. Dysfunction in oxidative phosphorylation and mitochondrial ROS production cause the release of damage-associated molecular patterns from dying hepatocytes, leading to activation of innate immunity and trans-differentiation of hepatic stellate cells, thereby driving fibrosis in NASH.

Serum iron fluctuations link ferroptosis process with mortality and prognosis of acute pancreatitis

Recently, the existence of ferroptosis has been confirmed in chronic pancreatitis. However, its role in acute pancreatitis (AP) process, especially in critical status, has not yet been mentioned. To verify this hypothesis, we included 873 AP patients (training set) and 1,188 NAFLD patients (internal validation set) selected from MIMIC-III (Medical Information Mark for Intensive Care) database and 218 AP patients (external validation set) in Linshui County People's Hospital ICU data. We analyzed the correlation between mortality and ferroptosis associating factors (such as serum iron, ALP, lactate, etc.) in them through regression analysis. In addition, to test the significance of these factors, the nomogram, AUC, and DCA analysis were applied. The results showed that serum iron, IBC, ALP, and lactate (p < 0.05) were independent factors for the mortality and prognosis of these patients. These correlations suggest ferroptosis and follow-up cell programmed death may own an important clinical interference significance among this population.

Liraglutide attenuates type 2 diabetes mellitus-associated non-alcoholic fatty liver disease by activating AMPK/ACC signaling and inhibiting ferroptosis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is one of the most common complications of type 2 diabetes mellitus (T2DM). The pathogenesis of NAFLD involves multiple biological changes, including insulin resistance, oxidative stress, inflammation, as well as genetic and environmental factors. Liraglutide has been used to control blood sugar. But the impact of liraglutide on T2DM-associated NAFLD remains unclear. In this study, we investigated the impact and potential molecular mechanisms of inhibiting ferroptosis for liraglutide improves T2DM-associated NAFLD.

METHODS

Mice were fed on high-fat-diet and injected with streptozotocin to mimic T2DM-associated NAFLD and gene expression in liver was analysed by RNA-seq. The fast blood glucose was measured during the period of liraglutide and ferrostatin-1 administration. Hematoxylin and eosin staining was used to evaluate the pathological changes in the liver. The occurrence of hepatic ferroptosis was measured by lipid peroxidation in vivo. The mechanism of liraglutide inhibition ferroptosis was investigated by in vitro cell culture.

RESULTS

Liraglutide not only improved glucose metabolism, but also ameliorated tissue damage in the livers. Transcriptomic analysis indicated that liraglutide regulates lipid metabolism related signaling including AMPK and ACC. Furthermore, ferroptosis inhibitor rather than other cell death inhibitors rescued liver cell viability in the presence of high glucose. Mechanistically, liraglutide-induced activation of AMPK phosphorylated ACC, while AMPK inhibitor compound C blocked the liraglutide-mediated suppression of ferroptosis. Moreover, ferroptosis inhibitor restored liver function in T2DM mice in vivo.

CONCLUSIONS

These findings indicate that liraglutide ameliorates the T2DM-associated NAFLD, which possibly through the activation of AMPK/ACC pathway and inhibition of ferroptosis.

Recent progress in the effect of ferroptosis of HSCs on the development of liver fibrosis

Fibrosis is a common pathological process that must take place for multiple chronic liver diseases to develop into cirrhosis and liver cancer. Liver fibrosis (LF) is regulated by various cytokines and signaling pathways in its occurrence and development. Ferroptosis is an important mode of cell death caused by iron-dependent oxidative damage and is regulated by iron metabolism and lipid peroxidation signaling pathways. In recent years, numerous studies have shown that ferroptosis is closely related to LF. As the main material secreted by the extracellular matrix, hepatic stellate cells (HSCs) are a general concern in the development of LF. Therefore, targeting HSC ferroptosis against LF is crucial. This review describes the current status of treating LF by inducing HSC ferroptosis that would aid studies in better understanding the current knowledge on ferroptosis in HSCs and the future research direction in this field.

MicroRNAs and Nonalcoholic Steatohepatitis: A Review

Non-alcoholic fatty liver disease (NAFLD) is a clinicopathologic syndrome caused by fat deposition in hepatocytes. Patients with nonalcoholic steatohepatitis (NASH), an advanced form of NAFLD with severe fibrosis, are at high risk for liver-related complications, including hepatocellular carcinoma (HCC). However, the mechanism of progression from simple fat deposition to NASH is complex, and previous reports have linked NAFLD to gut microbiota, bile acids, immunity, adipokines, oxidative stress, and genetic or epigenetic factors. NASH-related liver injury involves multiple cell types, and intercellular signaling is thought to be mediated by extracellular vesicles. MicroRNAs (miRNAs) are short, noncoding RNAs that play important roles as post-transcriptional regulators of gene expression and have been implicated in the pathogenesis of various diseases. Recently, many reports have implicated microRNAs in the pathogenesis of NALFD/NASH, suggesting that exosomal miRNAs are potential non-invasive and sensitive biomarkers and that the microRNAs involved in the mechanism of the progression of NASH may be potential therapeutic target molecules. We are interested in which miRNAs are involved in the pathogenesis of NASH and which are potential target molecules for therapy. We summarize targeted miRNAs associated with the etiology and progression of NASH and discuss each miRNA in terms of its pathophysiology, potential therapeutic applications, and efficacy as a NASH biomarker.

The Role of Tumor Necrosis Factor-Alpha in the Pathogenesis and Treatment of Nonalcoholic Fatty Liver Disease

PURPOSE OF REVIEW

To summarize experimental and clinical evidence on the association between tumor necrosis factor-α (TNF-α) and nonalcoholic fatty liver disease (NAFLD) and discuss potential treatment considerations.

RECENT FINDINGS

Experimental evidence suggests that TNF-α is a cytokine with a critical role in the pathogenesis of NAFLD. Although, the production of TNF-α may be an early event during the course of nonalcoholic fatty liver (NAFL), TNF-α may play a more substantial role in the pathogenesis of nonalcoholic steatohepatitis (NASH) and NAFLD-associated fibrosis. Moreover, TNF-α may potentiate hepatic insulin resistance, thus interconnecting inflammatory with metabolic signals and possibly contributing to the development of NAFLD-related comorbidities, including cardiovascular disease, hepatocellular carcinoma, and extra-hepatic malignancies. In clinical terms, TNF-α is probably associated with the severity of NAFLD; circulating TNF-α gradually increases from controls to patients with NAFL, and then, to patients with NASH. Given this potential association, various therapeutic interventions (obeticholic acid, peroxisome proliferator-activated receptors, sodium-glucose co-transporter 2 inhibitors, glucagon-like peptide-1 receptor agonists, probiotics, synbiotics, rifaximin, vitamin E, pentoxifylline, ursodeoxycholic acid, fibroblast growth factor-21, n-3 polyunsaturated fatty acids, statins, angiotensin receptor blockers) have been evaluated for their effect on TNF-α and NAFLD. Interestingly, anti-TNF biologics have shown favorable metabolic and hepatic effects, which may open a possible therapeutic window for the management of advanced NAFLD. The potential key pathogenic role of TNF-α in NAFLD warrants further investigation and may have important diagnostic and therapeutic implications.

Oxidative Stress Initiates Receptor-Interacting Protein Kinase-3/Mixed Lineage Kinase Domain-Like-Mediated Corneal Epithelial Necroptosis and Nucleotide-Binding Oligomerization Domain-Like Receptor Protein 3 Inflammasome Signaling during Fungal Keratitis

Fungal keratitis remains a major cause of severe visual loss in developing countries because of limited choices of therapy. The progression of fungal keratitis is a race between the innate immune system and the outgrowth of fungal conidia. Programmed necrosis (necroptosis), a type of proinflammatory cell death, has been recognized as a critical pathologic change in several diseases. However, the role and potential regulatory mechanisms of necroptosis have not been investigated in corneal diseases. The current study showed, for the first time, that fungal infection triggered significant corneal epithelial necroptosis in human/mouse/in vitro models. Moreover, a reduction in excessive reactive oxygen species release effectively prevented necroptosis. NLRP3 knockout did not affect necroptosis in vivo. In contrast, ablation of necroptosis via RIPK3 knockout significantly delayed migration and inhibited the nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome in macrophages, which enhanced the progression of fungal keratitis. Taking these findings together, the study indicated that overproduction of reactive oxygen species in fungal keratitis leads to significant necroptosis in the corneal epithelium. Furthermore, the necroptotic stimuli-mediated NLRP3 inflammasome serves as a driving force in host defense against fungal infection.

GAS5 protects against nonalcoholic fatty liver disease via miR-28a-5p/MARCH7/NLRP3 axis-mediated pyroptosis

Nonalcoholic fatty liver disease (NAFLD) is characterised by hepatic steatosis, inflammation, and insulin resistance. The role of long noncoding RNA (lncRNA)-regulated pyroptosis in NAFLD development remains largely unknown. This study aimed to investigate whether NAFLD development is controlled by lncRNA growth-arrest specific transcript 5 (GAS5)/miR-28a-5p/membrane associated ring-CH-type finger 7 (MARCH7)-mediated pyroptosis using in vivo and in vitro models. First, GAS5 expression was decreased but miR-28a-5p expression was increased in the livers of NAFLD patients, high-fat diet (HFD)-fed mice and leptin-deficient obese (Ob/Ob) mice. Furthermore, GAS5 suppressed while miR-28a-5p promoted NAFLD development, and overexpression of miR-28a-5p reversed the GAS5 overexpression-induced attenuation of NAFLD. Mechanistically, GAS5 served as a sponge of miR-28a-5p, and miR-28a-5p enhanced pyroptosis by targeting the 3' untranslated region (UTR) of the E3 ligase MARCH7 during NAFLD development. MARCH7 interacted with the NOD-like receptor protein 3 (NLRP3) protein, resulting in proteasomal degradation of NLRP3 to inhibit pyroptosis. As expected, MARCH7 knockdown abolished the miR-28a-5p knockdown-induced inhibition of NAFLD development, and the ubiquitin E3 ligase-inactive mutant (W589A/I556A) of MARCH7 failed to inhibit NAFLD development. In conclusion, GAS5 protected against NAFLD development by binding to miR-28a-5p, miR-28a-5p promoted NAFLD development by targeting MARCH7, and MARCH7 ameliorated NAFLD by suppressing NLRP3-mediated pyroptosis. The GAS5/miR-28a-5p/MARCH7/NLRP3 axis plays an important role in NAFLD progression, and it might be a biomarker for NAFLD.

GRP78/BiP alleviates oxLDL-induced hepatotoxicity in familial hypercholesterolemia caused by missense variants of LDLR in a HepG2 cellular model

BACKGROUND AND AIMS

The accumulation of misfolded proteins, encoded by genetic variants of functional genes leads to Endoplasmic Reticulum (ER) stress, which is a critical consequence in human disorders such as familial hypercholesterolemia, cardiovascular and hepatic diseases. In addition to the identification of ER stress as a contributing factor to pathogenicity, extensive studies on the role of oxidized Low-Density Lipoprotein (oxLDL) and its ill effects in expediting cardiovascular diseases and other metabolic comorbidities are well documented. However, the current understanding of its role in hepatic insults needs to be revised. This study elucidates the molecular mechanisms underlying the progression of oxLDL and ER stress-induced cytotoxicity in HepG2.

METHODS

HepG2 cells stably expressing wild-type Low-Density lipoprotein receptor (WT-LDLR) and missense variants of LDLR that are pathogenically associated with familial hypercholesterolemia were used as the in vitro models. The relative mRNA expression and protein profiles of ER stress sensors, inflammatory and apoptotic markers, together with cytotoxic assays and measurement of mitochondrial membrane potential, were carried out in HepG2 cells treated with 100 µg per ml oxLDL for 24 to 48 h. 1-way or 2-way ANOVA was used for statistical analyses of datasets.

RESULTS

ER stress responses are elicited along all three arms of the unfolded protein response (UPR), with adverse cytotoxic and inflammatory responses in oxLDL-treated conditions. Interestingly, oxLDL-treated ER-stressed HepG2 cells manifested intriguingly low expression of BiP- the master regulator of ER stress, as observed earlier by various researchers in liver biopsies of Non-Alcoholic Steatohepatitis (NASH) patients. This study shows that overexpression of BiP rescues hepatic cells from cytotoxic and inflammatory mechanisms instigated by ER stress in combination with oxLDL, along the ER and mitochondrial membrane and restores cellular homeostasis.

CONCLUSION

The data provide interesting leads that identify patients with familial hypercholesterolemia conditions and potentially other Endoplasmic Reticulum Associated Degradation (ERAD) diseases as highly susceptible to developing hepatic insults with molecular signatures like those manifested in Non-Alcoholic Fatty Liver Disease (NAFLD) and NASH.

LIMITATIONS AND FUTURE PERSPECTIVES

Although the use of HepG2 cells as the model is a major caveat of the study, the findings of this research may be used as the pilot study to expand further investigations in primary hepatocytes or iPSC- derived cellular models.

Identification of ferroptosis-related genes in the progress of NASH

Background

Non-alcoholic steatohepatitis (NASH) is becoming more widespread, and some similarities exist between its etiology and ferroptosis. However, there are limited investigations on which ferroptosis-related genes (FRGs) are regulated in NASH and how to regulate them. We screened and validated the pivotal genes linked to ferroptosis in NASH to comprehend the function of ferroptosis in the development of NASH.

Methods

Two mRNA expression data were obtained from the Gene Expression Omnibus (GEO) as the training set and validation set respectively. FRGs were downloaded from FerrDb. The candidate genes were obtained from the intersection between differentially expressed genes (DEGs) and FRGs, and further analyzed using the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). The hub genes were identified by the protein-protein interaction (PPI) network and Cytoscape. Then, FRGs closely related to the severity of NASH were identified and further confirmed using the validation set and mouse models. Ultimately, based on these genes, a diagnostic model was established to differentiate NASH from normal tissues using another data set from GEO.

Results

A total of 327 FRGs in NASH were acquired and subjected to GSEA. And 42 candidate genes were attained by overlapping the 585 FRGs with 2823 DEGs, and enrichment analysis revealed that these genes were primarily engaged in the fatty acid metabolic, inflammatory response, and oxidative stress. A total of 10 hub genes (PTGS2、IL1B、IL6、NQO1、ZFP36、SIRT1、ATF3、CDKN1A、EGR1、NOX4) were then screened by PPI network. The association between the expression of 10 hub genes and the progress of NASH was subsequently evaluated by a training set and verified by a validation set and mouse models. CDKN1A was up-regulated along with the development of NASH while SIRT1 was negatively correlated with the course of the disease. And the diagnostic model based on CDKN1A and SIRT1 successfully distinguished NASH from normal samples.

Conclusion

In summary, our findings provide a new approach for the diagnosis, prognosis, and treatment of NASH based on FRGs, while advancing our understanding of ferroptosis in NASH.

Supression Thioredoxin reductase 3 exacerbates the progression of liver cirrhosis via activation of ferroptosis pathway

AIMS

In the past decades, Txnrd3 as selenoprotein is considered to be highly expressed in testis and participate in sperm mature; however its role in liver diseases needs further study. Iron is essential for humans and animals, while its overload could damage to multiple organs. However, role of Txnrd3 and iron in cirrhosis is still unclear.

MATERIALS AND METHODS

Forty 8-week-old wild-type and forty Txnrd3-/- mice were selected to build liver cirrhosis model using Thiacetamide solution, deposition of iron in liver was observed via Prussian blue staining. Txnrd3 overexpression/knockdown model in vitro was constructed based on cell transfection techniques in AML12 cells, expression abundance of ferroptosis pathway genes within cells and tissues were determined by qRT-PCR and Western Blot.

KEY FINDINGS

Results showed that Txnrd3-/- mice developed more pronounced liver damage, accompanied by reduced GPX4 expression and iron deposition. A significant decrease in the expression abundance of GPX4 was also detected in Txnrd3 knock-down AML12 cells. In summary, Txnrd3 knockdown could result in iron overload and ferroptosis pathway activation within liver tissues and hepatocytes, ultimately lead to the occurrence of liver injury and cirrhosis.

SIGNIFICANCE

These results will provide biological markers for early diagnosis during cirrhosis and lay a theoretical basis for clinical therapy.

Oleanolic acid inhibits mercury chloride induced-liver ferroptosis by regulating ROS/iron overload

Mercury chloride can cause severe liver injury, which involves multiple mechanisms. Ferroptosis plays an important role in regulating the development and progression of liver pathology. Oleanolic acid (OA), a triterpenoid compound widely exists in fruits, has liver protective properties. In this study, we investigated the role of ferroptosis in mercury chloride-induced liver injury and the intervention effect of OA, and clarified the potential mechanism. We found that mercury chloride-induced oxidative stress in liver tissues and cells, leading to lipid peroxidation and iron overload, thereby reducing the expression levels of GPX4 and SLC7A11, and increasing the expression level of TRF1, OA pretreatment improved the changes of GPX4, SLC7A11 and TRF1 induced by mercury chloride, which were related to its inhibition of oxidative stress. Furthermore, We pretreated cells with OA, VC, and Fer-1, respectively and found that VC pretreatment reduced oxidative stress and significantly reversed the gene and protein expressions of GPX4, SLC7A11, and TRF1 in mercury chloride-exposed cells (P < 0.05, vs. HgCl₂ group), however, the protein expression level of GPX4 in OA pre-treatment group was lower than that in VC pre-treatment group (P < 0.05). Fer-1 pretreatment decreased the level of iron ions in cells, increased the gene and protein expression levels of GPX4 and SLC7A11, and decreased the gene and protein expression levels of TRF1 (P < 0.05, vs. HgCl₂ group), however, the protein expression levels of GPX4 and SLC7A11 in OA pre-treatment group were lower than those in Fer-1 pre-treatment group (P < 0.05). Moreover, vivo experiments also demonstrated that pre-treatment with OA, VC, and Fer-1 reversed the changes in gene expression levels of Nrf2 and SOD1, and protein expression of GPX4 induced by mercury chloride (P < 0.05, vs. HgCl₂ group), meanwhile, the difference was not statistically significant among OA, VC, and Fer-1 pretreatment. The improvement effect of OA pretreatment on the change in TFR1 protein expression caused by mercury chloride was similar to that of Fer-1 and VC, however, the intervention effect of OA on SLC7A11 protein expression was not as good as Fer-1 and VC pre-treatment. To sum up, all these results suggest that ferroptosis is involved in mercury chloride-induced liver injury, OA pretreatment alleviated mercury chloride-induced ferroptosis by inhibiting ROS production and iron ion overload, and then alleviate the liver injury.

Targeting ferroptosis, a novel programmed cell death, for the potential of alcohol-related liver disease therapy

Ferroptosis is a new iron-dependent cell death mode, which is different from the other types of programmed cell death, such as apoptosis, necrosis, and autophagy. Ferroptosis is characterized by a process in which fatal lipids from lipid peroxidation accumulate in cells and eventually lead to cell death. Alcohol-related liver disease (ALD) is a type of liver injury caused by excessive alcohol intake. Alcohol-related liver disease is a broad-spectrum disease category, which includes fatty liver, steatohepatitis, hepatitis, cirrhosis, and hepatocellular tumors. Recent studies have found that ferroptosis is involved in the pathological development of non-viral liver diseases. Therefore, ferroptosis may be an ideal target for the treatment of non-viral liver diseases. In this review article, we will elaborate the molecular mechanism and regulatory mechanism of ferroptosis, explore the key role of ferroptosis in the Alcohol-related liver disease process, and summarize the existing targeted ferroptosis drugs and their feasibility for the treatment of Alcohol-related liver disease.

RIPK3 dampens mitochondrial bioenergetics and lipid droplet dynamics in metabolic liver disease

BACKGROUND AND AIMS

Receptor-interacting protein kinase 3 (RIPK3) mediates NAFLD progression, but its metabolic function is unclear. Here, we aimed to investigate the role of RIPK3 in modulating mitochondria function, coupled with lipid droplet (LD) architecture in NAFLD.

APPROACH AND RESULTS

Functional studies evaluating mitochondria and LD biology were performed in wild-type (WT) and Ripk3-/- mice fed a choline-deficient, amino acid-defined (CDAA) diet for 32 and 66 weeks and in CRISPR-Cas9 Ripk3 -null fat-loaded immortalized hepatocytes. The association between hepatic perilipin (PLIN) 1 and 5, RIPK3, and disease severity was also addressed in a cohort of patients with NAFLD and in PLIN1 -associated familial partial lipodystrophy. Ripk3 deficiency rescued impairment in mitochondrial biogenesis, bioenergetics, and function in CDAA diet-fed mice and fat-loaded hepatocytes. Ripk3 deficiency was accompanied by a strong upregulation of antioxidant systems, leading to diminished oxidative stress upon fat loading both in vivo and in vitro. Strikingly, Ripk3-/- hepatocytes displayed smaller size LD in higher numbers than WT cells after incubation with free fatty acids. Ripk3 deficiency upregulated adipocyte and hepatic levels of LD-associated proteins PLIN1 and PLIN5. PLIN1 upregulation controlled LD structure and diminished mitochondrial stress upon free fatty acid overload in Ripk3-/- hepatocytes and was associated with diminished human NAFLD severity. Conversely, a pathogenic PLIN1 frameshift variant was associated with NAFLD and fibrosis, as well as with increased hepatic RIPK3 levels in familial partial lipodystrophy.

CONCLUSIONS

Ripk3 deficiency restores mitochondria bioenergetics and impacts LD dynamics. RIPK3 inhibition is promising in ameliorating NAFLD.

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.

The novel hepatoprotective mechanisms of silibinin-phospholipid complex against d-GalN/LPS-induced acute liver injury

BACKGROUND & AIMS

Silibinin-phospholipid complex (SPC) has been utilized to treat acute liver injury clinically. Nevertheless, the hepatoprotective mechanism of SPC remains to be further dissected in response to new insights into the pathogenesis of acute liver injury. Very recently, we have documented, for the first time, that M2-like macrophages exert the hepatoprotection against acute insult through inhibiting necroptosis-S100A9-necroinflammation. In the present work, we integrated this new finding into the mechanism of action of SPC, and attempted to dissect the hepatoprotective mechanism of SPC from this new perspective.

METHODS

SPC and corresponding controls were administered intragastrically into control mice subjected to d-GalN/LPS challenge. The hepatic damage was assessed, and the expression of necroptosis-S100A9-necroinflammation signaling molecules was detected. The correlation between SPC and macrophage activation was investigated. The expression of miR-223-3p and its regulation on macrophage activation were analyzed. The targeted inhibitory effects of miR-223-3p on necroptosis and necroinflammation signaling molecules were confirmed.

RESULTS

SPC alleviated remarkably the hepatic damage triggered by d-GalN/LPS. The administration of SPC inhibited the expression of necroptosis-S100A9-necroinflammation signaling molecules. The levels of M2-like macrophage markers were increased significantly in SPC-treated mice or macrophages. miR-223-3p expression was enhanced in SPC-treated mice. miR-223-3p transfer led to up-regulated expression of M2-like macrophage markers. miR-223-3p directly targeted 3' UTR of RIPK3 and NLRP3, and the expression of necroptosis and necroinflammation signaling molecules was inhibited in miR-223-3p-transferred hepatocytes and macrophages.

CONCLUSIONS

SPC alleviates acute liver injury through up-regulating the expression of miR-223-3p. MiR-223-3p further promotes M2-like macrophage activation and the targeted inhibition of necroptosis and necroinflammation. Our findings provide novel insight into the hepatoprotective mechanism of SPC against acute liver injury.