Cell Death in Liver Diseases: A Review

Metabolic dysfunction: The silenced connection with fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) represents a global public health burden. Despite the increase in its prevalence, the disease has not received sufficient attention compared to the associated diseases such as diabetes mellitus and obesity. In 2020 it was proposed to rename NAFLD to metabolic dysfunction-associated fatty liver disease (MAFLD) in order to recognize the metabolic risk factors and the complex pathophysiological mechanisms associated with its development. Furthermore, along with the implementation of the proposed diagnostic criteria, the aim is to address the whole clinical spectrum of the disease, regardless of BMI and the presence of other hepatic comorbidities. As would it be expected with such a paradigm shift, differing viewpoints have emerged regarding the benefits and disadvantages of renaming fatty liver disease. The following review aims to describe the way to the MAFLD from a historical, pathophysiological and clinical perspective in order to highlight why MAFLD is the approach to follow.

Immunogenic necroptosis in liver diseases: mechanisms and therapeutic potential

Necroptosis has received increasing attention and is extensively studied as a recently discovered mode of cell death distinct from necrosis and apoptosis. It is a programmed cell death with a necrotic morphology that occurs in various biological processes, including inflammation, immune response, embryonic development, and metabolic abnormalities. Necroptosis is indispensable in maintaining tissue homeostasis in vivo and closely correlates with the occurrence and development of various diseases. First, we outlined the etiology of necroptosis and how it affects the onset and development of prevalent liver diseases in this review. Additionally, we reviewed the therapeutic strategy by targeting the necroptosis pathway in related liver diseases. We conclude that the necroptosis signaling pathway is critical in the physiological control of liver diseases' onset, progression, and prognosis. It will likely be used as a therapeutic target in the future. Further research is required to determine the mechanisms governing the necroptosis signaling pathway and the effector molecules.

Differences in hepatocellular iron metabolism underlie sexual dimorphism in hepatocyte ferroptosis

Males show higher incidence and severity than females in hepatic injury and many liver diseases, but the mechanisms are not well understood. Ferroptosis, an iron-mediated lipid peroxidation-dependent death, plays an important role in the pathogenesis of liver diseases. We determined whether hepatocyte ferroptosis displays gender difference, accounting for sexual dimorphism in liver diseases. Compared to female hepatocytes, male hepatocytes were much more vulnerable to ferroptosis by iron and pharmacological inducers including RSL3 and iFSP1. Male but not female hepatocytes exhibited significant increases in mitochondrial Fe2+ and mitochondrial ROS (mtROS) contents. Female hepatocytes showed a lower expression of iron importer transferrin receptor 1 (TfR1) and mitochondrial iron importer mitoferrin 1 (Mfrn1), but a higher expression of iron storage protein ferritin heavy chain 1 (FTH1). It is well known that TfR1 expression is positively correlated with ferroptosis. Herein, we showed that silencing FTH1 enhanced while knockdown of Mfrn1 decreased ferroptosis in HepG2 cells. Removing female hormones by ovariectomy (OVX) did not dampen but rather enhanced hepatocyte resistance to ferroptosis. Mechanistically, OVX potentiated the decrease in TfR1 and increase in FTH1 expression. OVX also increased FSP1 expression in ERK-dependent manner. Elevation in FSP1 suppressed mitochondrial Fe2+ accumulation and mtROS production, constituting a novel mechanism of FSP1-mediated inhibition of ferroptosis. In conclusion, differences in hepatocellular iron handling between male and female account, at least in part, for sexual dimorphism in induced ferroptosis of the hepatocytes.

The mechanism of ferroptosis and its related diseases

Ferroptosis, a regulated form of cellular death characterized by the iron-mediated accumulation of lipid peroxides, provides a novel avenue for delving into the intersection of cellular metabolism, oxidative stress, and disease pathology. We have witnessed a mounting fascination with ferroptosis, attributed to its pivotal roles across diverse physiological and pathological conditions including developmental processes, metabolic dynamics, oncogenic pathways, neurodegenerative cascades, and traumatic tissue injuries. By unraveling the intricate underpinnings of the molecular machinery, pivotal contributors, intricate signaling conduits, and regulatory networks governing ferroptosis, researchers aim to bridge the gap between the intricacies of this unique mode of cellular death and its multifaceted implications for health and disease. In light of the rapidly advancing landscape of ferroptosis research, we present a comprehensive review aiming at the extensive implications of ferroptosis in the origins and progress of human diseases. This review concludes with a careful analysis of potential treatment approaches carefully designed to either inhibit or promote ferroptosis. Additionally, we have succinctly summarized the potential therapeutic targets and compounds that hold promise in targeting ferroptosis within various diseases. This pivotal facet underscores the burgeoning possibilities for manipulating ferroptosis as a therapeutic strategy. In summary, this review enriched the insights of both investigators and practitioners, while fostering an elevated comprehension of ferroptosis and its latent translational utilities. By revealing the basic processes and investigating treatment possibilities, this review provides a crucial resource for scientists and medical practitioners, aiding in a deep understanding of ferroptosis and its effects in various disease situations.

Mitochondrial Dysfunction-Associated Mechanisms in the Development of Chronic Liver Diseases

The liver is a major metabolic organ that performs many essential biological functions such as detoxification and the synthesis of proteins and biochemicals necessary for digestion and growth. Any disruption in normal liver function can lead to the development of more severe liver disorders. Overall, about 3 million Americans have some type of liver disease and 5.5 million people have progressive liver disease or cirrhosis, in which scar tissue replaces the healthy liver tissue. An estimated 20% to 30% of adults have excess fat in their livers, a condition called steatosis. The most common etiologies for steatosis development are (1) high caloric intake that causes non-alcoholic fatty liver disease (NAFLD) and (2) excessive alcohol consumption, which results in alcohol-associated liver disease (ALD). NAFLD is now termed "metabolic-dysfunction-associated steatotic liver disease" (MASLD), which reflects its association with the metabolic syndrome and conditions including diabetes, high blood pressure, high cholesterol and obesity. ALD represents a spectrum of liver injury that ranges from hepatic steatosis to more advanced liver pathologies, including alcoholic hepatitis (AH), alcohol-associated cirrhosis (AC) and acute AH, presenting as acute-on-chronic liver failure. The predominant liver cells, hepatocytes, comprise more than 70% of the total liver mass in human adults and are the basic metabolic cells. Mitochondria are intracellular organelles that are the principal sources of energy in hepatocytes and play a major role in oxidative metabolism and sustaining liver cell energy needs. In addition to regulating cellular energy homeostasis, mitochondria perform other key physiologic and metabolic activities, including ion homeostasis, reactive oxygen species (ROS) generation, redox signaling and participation in cell injury/death. Here, we discuss the main mechanism of mitochondrial dysfunction in chronic liver disease and some treatment strategies available for targeting mitochondria.

Future directions in acute liver failure

Acute liver failure (ALF) describes a clinical syndrome of rapid hepatocyte injury leading to liver failure manifested by coagulopathy and encephalopathy in the absence of pre-existing cirrhosis. The hallmark diagnostic features are a prolonged prothrombin time (ie, an international normalized ratio of prothrombin time of ≥1.5) and any degree of mental status alteration (HE). As a rare, orphan disease, it seemed an obvious target for a multicenter network. The Acute Liver Failure Study Group (ALFSG) began in 1997 to more thoroughly study and understand the causes, natural history, and management of ALF. Over the course of 22 years, 3364 adult patients were enrolled in the study registry (2614 ALF and 857 acute liver injury-international normalized ratio 2.0 but no encephalopathy-ALI) and >150,000 biosamples collected, including serum, plasma, urine, DNA, and liver tissue. Within the Registry study sites, 4 prospective substudies were conducted and published, 2 interventional ( N -acetylcysteine and ornithine phenylacetate), 1 prognostic [ 13 C-methacetin breath test (MBT)], and 1 mechanistic (rotational thromboelastometry). To review ALFSG's accomplishments and consider next steps, a 2-day in-person conference was held at UT Southwestern Medical Center, Dallas, TX, entitled "Acute Liver Failure: Science and Practice," in May 2022. To summarize the important findings in the field, this review highlights the current state of understanding of ALF and, more importantly, asks what further studies are needed to improve our understanding of the pathogenesis, natural history, and management of this unique and dramatic condition.

Comparison of nickel oxide nano and microparticles toxicity in rat liver: molecular, biochemical, and histopathological study

The unique properties of nickel oxide nanoparticles distinguish it from classical nickel compounds, increasing its use in agriculture, industry, and many industrial areas. The aim of this study is to investigate the possible toxicity of nickel oxide and nickel oxide nanoparticles in the liver. For this purpose, Wistar rats were given nickel oxide and nickel oxide nanoparticles orally, intraperitoneally, and intravenously for 21 days. Liver organ weight, biochemical and hematological parameters, oxidative stress (malondialdehyde, catalase, superoxide dismutase, glutathione peroxidase, and glutathione S transferase), acetylcholinesterase activities, inflammation levels, apoptotic markers, and histopathological changes were evaluated comparatively. When the data obtained were examined in general, it was observed that nickel oxide nanoparticles caused more hepatotoxicity in liver tissue than nickel oxide in terms of oxidative stress parameters, apoptotic markers, inflammation indicators, and other parameters examined. The results suggest that toxicity induced by both nickel oxide and nickel oxide nanoparticles plays an important role in hepatocyte apoptosis.

Mitochondrial IRG1 traps MCL-1 to induce hepatocyte apoptosis and promote carcinogenesis

Hepatocarcinogenesis is initiated by repeated hepatocyte death and liver damage, and the underlying mechanisms mediating cell death and the subsequent carcinogenesis remain to be fully investigated. Immunoresponsive gene 1 (IRG1) and its enzymatic metabolite itaconate are known to suppress inflammation in myeloid cells, and its expression in liver parenchymal hepatocytes is currently determined. However, the potential roles of IRG1 in hepatocarcinogenesis are still unknown. Here, using the diethylnitrosamine (DEN)-induced hepatocarcinogenesis mouse model, we found that IRG1 expression in hepatocytes was markedly induced upon DEN administration. The DEN-induced IRG1 was then determined to promote the intrinsic mitochondrial apoptosis of hepatocytes and liver damage, thus enhancing the subsequent hepatocarcinogenesis. Mechanistically, the mitochondrial IRG1 could associate and trap anti-apoptotic MCL-1 to inhibit the interaction between MCL-1 and pro-apoptotic Bim, thus promoting Bim activation and downstream Bax mitochondrial translocation, and then releasing cytochrome c and initiating apoptosis. Thus, the inducible mitochondrial IRG1 promotes hepatocyte apoptosis and the following hepatocarcinogenesis, which provides mechanistic insight and a potential target for preventing liver injury and HCC.

Hepatocytic Ballooning in Non-alcoholic Steatohepatitis: Bridging the Knowledge Gap and Charting Future Avenues

Non-alcoholic steatohepatitis (NASH) is emerging as a significant global health concern, characterized by hepatic lipid accumulation, inflammation, and hepatocellular injury. Hepatocytic ballooning, a histological feature of NASH, has gained prominence for its role in disease progression and potential as a therapeutic target. This review provides an overview of the current knowledge regarding hepatocytic ballooning in NASH, highlighting the key molecular and cellular mechanisms implicated in its development. We delve into the intricate interplay of metabolic dysregulation, oxidative stress, and lipid toxicity as drivers of hepatocytic ballooning, shedding light on the pathways responsible for its initiation and perpetuation. Furthermore, we explore the diagnostic challenges associated with hepatocytic ballooning and its significance as a prognostic indicator in NASH patients. While hepatocytic ballooning holds promise as a therapeutic target, this abstract discusses the various experimental and clinical approaches to ameliorate this histological hallmark. Potential interventions, including lifestyle modifications, pharmacological agents, and emerging therapies, are evaluated in terms of their efficacy and safety profiles. In conclusion, this review underscores the need to bridge the knowledge gap surrounding hepatocytic ballooning in NASH and emphasizes its importance in understanding disease pathogenesis and progression. By charting future research avenues and clinical strategies, we aspire to advance our comprehension of NASH and ultimately improve patient outcomes in this rapidly evolving field of hepatology.

Preventive Effect of 6-shogaol on D-galactosamine Induced Hepatotoxicity Through NF-?B/MAPK Signaling Pathway in Rats

This analysis aims to see whether 6-shogaol could protect rats against D-galactosamine (D-GalN)-induced Hepatotoxicity. The Wistar rats were divided into four groups (n=6). Group 1 received a standard diet, Group 2 received an oral administration of 6-shogaol (20 mg/kg b.wt), Group 3 received an intraperitoneal injection of D-GalN (400 mg/kg b.wt) on 21st day, and Group 4 received an oral administration of 6-shogaol (20mg/kg b.wt) for 21 days and D-GalN (400 mg/kg b.wt) injection only on 21st day. The hepatic marker enzymes activity, lipid peroxidative markers level increased significantly and antioxidant activity/level significantly reduced in D-GalN-induced rats. 6-shogaol Pretreatment effectively improves the above changes in D-GalN-induced rats. Further, inflammatory marker expression and MAPK signaling molecules were downregulated by 6-shogaol. These findings showed that 6-shogaol exerts hepatoprotective effects via the enhanced antioxidant system and attenuated the inflammation and MAPK signaling pathway in D-GalN-induced rats.

GAS5-inhibited hepatocyte pyroptosis contributes to hepatic stellate cell inactivation via microRNA-684 and AHR

Hepatocyte pyroptosis has been shown to be involved in liver damage progression. Previously, we found that growth arrest-specific 5 (GAS5) is a regulator of hepatic stellate cell (HSC) activation. However, whether GAS5 plays a role in hepatocyte pyroptosis remains unclear. In this study, reduced GAS5 was shown in CCl₄-treated mice and restoration of GAS5-inhibited liver fibrosis in vivo. Hepatocyte pyroptosis participated in the effects of GAS5-inhibited liver fibrosis, associated with reduced caspase-1, NLRP3, and IL-1β (hepatocyte pyroptosis markers). Notably, AHR expression, a suppressor of NLRP3, was enhanced by GAS5. Silencing AHR inhibited GAS5-mediated hepatocyte pyroptosis. GAS5 and AHR were targets of microRNA-684 (miR-684). In addition, the effects of GAS5 on hepatocyte pyroptosis could be inhibited by miR-684. Interestingly, GAS5-mediated hepatocyte pyroptosis contributed to HSC inactivation. In conclusion, we demonstrate that GAS5 inhibits hepatocyte pyroptosis and HSC activation, at least in part, via regulation of miR-684 and AHR.

Pyroptosis and gasdermins-Emerging insights and therapeutic opportunities in metabolic dysfunction-associated steatohepatitis

In recent years, there has been a rapid expansion in our understanding of regulated cell death, leading to the discovery of novel mechanisms that govern diverse cell death pathways. One recently discovered type of cell death is pyroptosis, initially identified in the 1990s as a caspase-1-dependent lytic cell death. However, further investigations have redefined pyroptosis as a regulated cell death that relies on the activation of pore-forming proteins, particularly the gasdermin family. Among the key regulators of pyroptosis is the inflammasome sensor NOD-like receptor 3 (NLRP3), a critical innate immune sensor responsible for regulating the activation of caspase-1 and gasdermin D. A deeper understanding of pyroptosis and its interplay with other forms of regulated cell death is emerging, shedding light on a complex regulatory network controlling pore-forming proteins and cell fate. Cell death processes play a central role in diseases such as metabolic dysfunction-associated steatotic liver disease, metabolic dysfunction-associated steatohepatitis, autoinflammatory disorders, and cancer. Cell death often acts as a starting point in these diseases, making it an appealing target for drug development. Yet, the complete molecular mechanisms are not fully understood, and new discoveries reveal promising novel avenues for therapeutic interventions. In this review, we summarize recent evidence on pathways and proteins controlling pyroptosis and gasdermins. Furthermore, we will address the role of pyroptosis and the gasdermin family in metabolic dysfunction-associated steatotic liver disease and steatohepatitis. Additionally, we highlight new potential therapeutic targets for treating metabolic dysfunction-associated steatohepatitis and other inflammatory-associated diseases.

Ferroptosis and mitochondrial dysfunction in acute central nervous system injury

Acute central nervous system injuries (ACNSI), encompassing traumatic brain injury (TBI), non-traumatic brain injury like stroke and encephalomeningitis, as well as spinal cord injuries, are linked to significant rates of disability and mortality globally. Nevertheless, effective and feasible treatment plans are still to be formulated. There are primary and secondary injuries occurred after ACNSI. Most ACNSIs exhibit comparable secondary injuries, which offer numerous potential therapeutic targets for enhancing clinical outcomes. Ferroptosis, a newly discovered form of cell death, is characterized as a lipid peroxidation process that is dependent on iron and oxidative conditions, which is also indispensable to mitochondria. Ferroptosis play a vital role in many neuropathological pathways, and ACNSIs may induce mitochondrial dysfunction, thereby indicating the essentiality of the mitochondrial connection to ferroptosis in ACNSIs. Nevertheless, there remains a lack of clarity regarding the involvement of mitochondria in the occurrence of ferroptosis as a secondary injuries of ACNSIs. In recent studies, anti-ferroptosis agents such as the ferroptosis inhibitor Ferrostain-1 and iron chelation therapy have shown potential in ameliorating the deleterious effects of ferroptosis in cases of traumatic ACNSI. The importance of this evidence is extremely significant in relation to the research and control of ACNSIs. Therefore, our review aims to provide researchers focusing on enhancing the therapeutic outcomes of ACNSIs with valuable insights by summarizing the physiopathological mechanisms of ACNSIs and exploring the correlation between ferroptosis, mitochondrial dysfunction, and ACNSIs.

New murine model of alcoholic hepatitis in obesity-induced metabolic-associated fatty liver disease

Metabolic-associated fatty liver disease (MAFLD) and alcoholic hepatitis (AH) are among the most prevalent liver diseases worldwide, and their coexistence is common in clinical practice. However, currently established models of MAFLD-AH coexistence do not fully replicate their pathological characteristics and require sophisticated experimental techniques. Therefore, we aimed to develop an easily replicable model that mimics obesity-induced MAFLD-AH in patients. Our goal was to establish a murine model that replicates MAFLD and AH coexistence, resulting in significant liver injury and inflammation. To this end, we administered a single ethanol gavage dose to ob/ob mice on a chow diet. The administration of a single dose of ethanol led to elevated serum transaminase levels, increased liver steatosis, and apoptosis in ob/ob mice. Furthermore, ethanol binge caused a significant increase in oxidative stress in ob/ob mice, as measured via 4-hydroxynonenal. Importantly, the single dose of ethanol also markedly exacerbated liver neutrophil infiltration and upregulated the hepatic mRNA expression of several chemokines and neutrophil-related proteins, including Cxcl1, Cxcl2, and Lcn2. Whole-liver transcriptomic analysis revealed that ethanol-induced changes in gene expression profile shared similar features with AH and MAFLD. In ob/ob mice, a single dose of ethanol binge caused significant liver injury and neutrophil infiltration. This easy-to-replicate murine model successfully mimics the pathological and clinical features of patients with coexisting MAFLD and AH and closely resembles the transcriptional regulation seen in human disease.

Mitochondria-associated programmed cell death as a therapeutic target for age-related disease

Mitochondria, ubiquitous double-membrane-bound organelles, regulate energy production, support cellular activities, harbor metabolic pathways, and, paradoxically, mediate cell fate. Evidence has shown mitochondria as points of convergence for diverse cell death-inducing pathways that trigger the various mechanisms underlying apoptotic and nonapoptotic programmed cell death. Thus, dysfunctional cellular pathways eventually lead or contribute to various age-related diseases, such as neurodegenerative, cardiovascular and metabolic diseases. Thus, mitochondrion-associated programmed cell death-based treatments show great therapeutic potential, providing novel insights in clinical trials. This review discusses mitochondrial quality control networks with activity triggered by stimuli and that maintain cellular homeostasis via mitohormesis, the mitochondrial unfolded protein response, and mitophagy. The review also presents details on various forms of mitochondria-associated programmed cell death, including apoptosis, necroptosis, ferroptosis, pyroptosis, parthanatos, and paraptosis, and highlights their involvement in age-related disease pathogenesis, collectively suggesting therapeutic directions for further research.

Atractylodin alleviates nonalcoholic fatty liver disease by regulating Nrf2-mediated ferroptosis

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide. Oxidative stress is one of the main inducers of NAFLD. Atractylodin (ART), a major active ingredient of Atractylodes lancea, possesses potential antioxidant and anti-inflammatory activity in many types of disease. In the current study, the underlying mechanism by which ART alleviates the progression of NAFLD was explored. The function of ART in facilitating NAFLD was investigated in vitro and in vivo. Functionally, ART attenuated high-fat diet (HFD)-induced NAFLD in mice and palmitic acid (PA)-induced oxidative stress in HepG2 cells. Furthermore, our data verified that ART attenuated HFD-induced NAFLD by inhibiting ferroptosis of hepatocyte cells, as evidenced by decreased Fe2+ concentration, reactive oxygen species (ROS) level, malondialdehyde (MDA) content, and increased glutathione (GSH) content. The protective effect of ART on the cell viability of hepatocytes was blocked by a specific ferroptosis inhibitor (ferrostatin-1). Mechanistically, ART treatment promoted the translocation of nuclear factor erythroid 2-related Factor 2 (NFE2L2/NRF2) and thus increased glutathione peroxidase 4 (GPX4), ferritin heavy chain 1 (FTH1), and solute carrier family 7 member 11 (SLC7A11) expression. Taken together, ART alleviates NAFLD by regulating Nrf2-mediated ferroptosis.

Differences in Hepatocellular Iron Metabolism Underlie Sexual Dimorphism in Hepatocyte Ferroptosis

Males show higher incidence and severity than females in hepatic injury and many liver diseases, but the mechanisms are not well understood. Ferroptosis, an iron-mediated lipid peroxidation-dependent death, plays an important role in the pathogenesis of liver diseases. We determined whether hepatocyte ferroptosis displays gender difference, accounting for sexual dimorphism in liver diseases. Compared to female hepatocytes, male hepatocytes were much more vulnerable to ferroptosis by iron and pharmacological inducers including RSL3 and iFSP1. Male but not female hepatocytes exhibited significant increases in mitochondrial Fe 2+ and mitochondrial ROS (mtROS) contents. Female hepatocytes showed a lower expression of iron importer transferrin receptor 1 (TfR1) and mitochondrial iron importer mitoferrin 1 (Mfrn1), but a higher expression of iron storage protein ferritin heavy chain 1 (FTH1). It is well known that TfR1 expression is positively correlated with ferroptosis. Herein, we showed that silencing FTH1 enhanced while knockdown of Mfrn1 decreased ferroptosis in HepG2 cells. Removing female hormones by ovariectomy (OVX) did not dampen but rather enhanced hepatocyte resistance to ferroptosis. Mechanistically, OVX potentiated the decrease in TfR1 and increase in FTH1 expression. OVX also increased FSP1 expression in ERK-dependent manner. Elevation in FSP1 suppressed mitochondrial Fe 2+ accumulation and mtROS production, constituting a novel mechanism of FSP1-mediated inhibition of ferroptosis. In conclusion, differences in hepatocellular iron handling between male and female account, at least in part, for sexual dimorphism in induced ferroptosis of the hepatocytes.

Unfolded protein response inhibits KAT2B/MLKL-mediated necroptosis of hepatocytes by promoting BMI1 level to ubiquitinate KAT2B

Unfolded protein response (UPR) plays an important role in the pathogenesis of many liver diseases. BMI1 has a liver protection effect, but whether it participates in the regulation of hepatocyte death through UPR is not well defined. Herein, the endoplasmic reticulum stress model was established by inducing hepatocyte line (MIHA) with tunicamycin (TM, 5 µg/ml). Cell counting kit-8 assay and flow cytometry were used to evaluate the viability and apoptosis of hepatocytes. The expression levels of BMI1, KAT2B, and proteins related to UPR (p-eIF2α, eIF2α, ATF4, and ATF6), NF-κB (p65 and p-p65), apoptosis (cleaved caspase-3, bcl-2, and bax) and necroptosis (p-MLKL and MLKL) were determined by Western blot. The relationship between KAT2B and BMI1 was determined by co-immunoprecipitation and ubiquitination assay. The results showed that TM not only promoted UPR, apoptosis, and necroptosis in hepatocytes but also upregulated the expression levels of BMI1 and KAT2B and activated NF-κB pathway. BAY-117082 reversed the effects of TM on viability, apoptosis, NF-κB pathway, and BMI1 but strengthened the effects of TM on KAT2B/MLKL-mediated necroptosis. BMI1 promoted the ubiquitination of KAT2B, and BMI1 overexpression reversed the effects of TM on viability, apoptosis, and KAT2B/MLKL-mediated necroptosis. In summary, overexpression of BMI1 promotes the ubiquitination of KAT2B to block the MLKL-mediated necroptosis of hepatocytes.

How to Preserve Steatotic Liver Grafts for Transplantation

Liver allograft steatosis is a significant risk factor for postoperative graft dysfunction and has been associated with inferior patient and graft survival, particularly in the case of moderate or severe macrovesicular steatosis. In recent years, the increasing incidence of obesity and fatty liver disease in the population has led to a higher proportion of steatotic liver grafts being used for transplantation, making the optimization of their preservation an urgent necessity. This review discusses the mechanisms behind the increased susceptibility of fatty livers to ischemia-reperfusion injury and provides an overview of the available strategies to improve their utilization for transplantation, with a focus on preclinical and clinical evidence supporting donor interventions, novel preservation solutions, and machine perfusion techniques.

Activation of Kupffer cells in NAFLD and NASH: mechanisms and therapeutic interventions

Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are emerging as the leading causes of liver disease worldwide. These conditions can lead to cirrhosis, liver cancer, liver failure, and other related ailments. At present, liver transplantation remains the sole treatment option for end-stage NASH, leading to a rapidly growing socioeconomic burden. Kupffer cells (KCs) are a dominant population of macrophages that reside in the liver, playing a crucial role in innate immunity. Their primary function includes phagocytosing exogenous substances, presenting antigens, and triggering immune responses. Moreover, they interact with other liver cells during the pathogenesis of NAFLD, and this crosstalk may either delay or exacerbate disease progression. Stimulation by endogenous signals triggers the activation of KCs, resulting in the expression of various inflammatory factors and chemokines, such as NLRP3, TNF-α, IL-1B, and IL-6, and contributing to the inflammatory cascade. In the past 5 years, significant advances have been made in understanding the biological properties and immune functions of KCs in NAFLD, including their interactions with tissue molecules, underlying molecular mechanisms, signaling pathways, and relevant therapeutic interventions. Having a comprehensive understanding of these mechanisms and characteristics can have enormous potential in guiding future strategies for the prevention and treatment of NAFLD.

Remove, Refine, Reduce: Cell Death in Biological Systems

Cell death is an important biological phenomenon [...].

Mori fructus aqueous extracts attenuates liver injury by inhibiting ferroptosis via the Nrf2 pathway

BACKGROUND

Liver fibrosis and hepatocellular carcinogenesis secondary to liver fibrosis are serious liver diseases with no effective treatments. Mori fructus aqueous extracts (MFAEs) have served as successful treatments for many types of liver injury including fibrosis although the molecular mechanisms are unknown at present.

PURPOSE

To investigate the effect of MFAEs in alleviating acute and chronic liver injury and tried to decipher the underlying mechanism.

METHODS AND RESULTS

Mice were divided into 5 groups (n = 8) for acute (groups: control, 0.3% CCl₄, bifendate (BD), 100 and 200 mg/kg MFAEs, 7 d) and chronic (groups: control, 10% CCl₄, BD, 100 and 200 mg/kg MFAEs, 4 weeks) liver injury study. Each mouse was injected intraperitoneally with 10 µL/g corn oil containing CCl₄ expect the control group. HepG2 cells were used in vitro study. Eighteen communal components were identified by UPLC-LTQ-Orbitrap-MS. We utilized a mouse model for acute and chronic liver injury using CCl₄ and MFAEs administration effectively blocked fibrosis and significantly inhibited inflammation in the liver. MFAEs activated the nuclear factor erythroid derived 2 like 2/heme oxygenase 1 (Nrf2/HO-1) pathway and promoted the synthesis of the antioxidants glutathione (GSH), superoxidedismutase (SOD) and glutathione peroxidase (GSH-Px) that resulted in reduced levels of CCl₄-induced oxidative stress molecules including reactive oxygen species. These extracts administered to mice also inhibited ferroptosis in the liver by regulating the expression of Acyl-CoA synthetase long chain family member 4 (ACSL4), solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4), thus reducing the occurrence of liver fibrosis. Both in vivo and in vitro tests indicated that the mechanism of MFAEs protection against liver fibrosis was linked to activation of Nrf2 signaling. These effects were blocked in vitro by the addition of a specific Nrf2 inhibitor.

CONCLUSION

MFAEs inhibited oxidative stress, ferroptosis and inflammation of the liver by activating Nrf2 signal pathway and provided a significant protective effect against CCl₄-induced liver fibrosis.

Dissecting the potential role of ferroptosis in liver diseases: an updated review

Ferroptosis is a novel form of cell death, manifested by iron-dependent, non-apoptotic manner resulting from the intracellular accumulation of large clusters of reactive oxygen species (ROS) and lipid peroxides due to abnormal iron metabolism. Since the liver is the main organ of human body for storing iron, it is essential to perform in-depth investigation on the role and mechanistic basis of ferroptosis in the context of divergent liver diseases. We previously summarized the emerging role of ferroptosis among various liver diseases, however, the past few years have been a surge in research establishing ferroptosis as the molecular basis or treatment option. This review article concentrated on the accumulating research progress of ferroptosis in a range of liver diseases such as acute liver injury/failure (ALI/ALF), immune-mediated hepatitis, alcoholic liver disease (ALD), nonalcoholic fatty liver disease and liver fibrosis. Ferroptosis may be a promising target for the prevention and treatment of various liver diseases, providing a strategy for exploring new therapeutic avenues for these entities.

Yes-associated protein inhibition ameliorates liver fibrosis and acute and chronic liver failure by decreasing ferroptosis and necroptosis

Background/aims

This study aims to determine which cell death modes contribute most in the progression of cirrhosis and acute-on-chronic liver failure (ACLF), and to investigate whether Yes associated protein (YAP) affects the disease process by regulating cell death.

Materials and methods

30C57BL/6 male mice were divided into five groups: control, carbon tetrachloride (CCl4)-induced liver fibrosis model, CCl4+verteporfin, CCl4+lipopolysaccharides (LPS) combined with the D-(+)-Galactosamine (LPS/D-GalN)-induced ACLF model, and ACLF + verteporfin. Patients with chronic hepatitis B (CHB), hepatitis B virus (HBV) related liver cirrhosis or ACLF were enrolled. Histology, immunohistochemistry, transmission electron microscopy, Western blot and ELISA were conducted to assess the roles of YAP and cell death in liver cirrhosis and ACLF, and to explore the effect of YAP inhibition on cell deaths.

Results

YAP was markedly increased in mice with liver fibrosis and ACLF, along with ferroptosis and necroptosis. Furthermore, YAP inhibition significantly suppressed fibrosis in CCl4-mediated liver fibrosis and ACLF-associated liver injury. Notably, CCl4 induced up-regulation of ACSL4 and RIPK3 and down-regulation of SLC7A11, key factors in ferroptosis and necroptosis. This was significantly abrogated by verteporfin treatment. Similar changes in ferroptosis and necroptosis were found in ACLF and ACLF + verteporfin groups. Consistent with the above findings in mice, we found that plasma YAP levels were gradually increased with the development of HBV-related liver fibrosis and ACLF.

Conclusion

Ferroptosis and necroptosis are involved in the development of liver cirrhosis and ACLF. Inhibition of YAP improved liver fibrosis and liver damage in ACLF through a reduction in ferroptosis and necroptosis. Our findings may help better understanding the role of YAP in liver fibrosis and ACLF.

Inaugurating a novel adjuvant therapy in urological cancers: Ferroptosis

Ferroptosis, a distinctive form of programmed cell death, is involved in numerous diseases with specific characteristics, including certain cell morphology, functions, biochemistry, and genetics, that differ from other forms of programmed cell death, such as apoptosis. Many studies have explored ferroptosis and its associated mechanisms, drugs, and clinical applications in diseases such as kidney injury, stroke, ischemia-reperfusion injury, and prostate cancer. In this review, we summarize the regulatory mechanisms of some ferroptosis inducers, such as enzalutamide and erastin. These are current research focuses and have already been studied extensively. In summary, this review focuses on the use of ferroptosis induction as a therapeutic strategy for treating tumors of the urinary system.

Involvement of Intracellular TAGE and the TAGE-RAGE-ROS Axis in the Onset and Progression of NAFLD/NASH

The repeated excessive intake of sugar, a factor that contributes to the onset of nonalcoholic fatty liver disease (NAFLD) and its progression to the chronic form of nonalcoholic steatohepatitis (NASH), markedly increases the hepatocyte content of glyceraldehyde (GA), a glucose/fructose metabolic intermediate. Toxic advanced glycation end-products (toxic AGEs, TAGE) are synthesized by cross-linking reactions between the aldehyde group of GA and the amino group of proteins, and their accumulation has been implicated in the development of NAFLD/NASH and hepatocellular carcinoma (HCC). Our previous findings not only showed that hepatocyte disorders were induced by the intracellular accumulation of TAGE, but they also indicated that extracellular leakage resulted in elevated TAGE concentrations in circulating fluids. Interactions between extracellular TAGE and receptor for AGEs (RAGE) affect intracellular signaling and reactive oxygen species (ROS) production, which may, in turn, contribute to the pathological changes observed in NAFLD/NASH. RAGE plays a role in the effects of the extracellular leakage of TAGE on the surrounding cells, which ultimately promote the onset and progression of NAFLD/NASH. This review describes the relationships between intracellular TAGE levels and hepatocyte and hepatic stellate cell (HSC) damage as well as the TAGE-RAGE-ROS axis in hepatocytes, HSC, and HCC cells. The "TAGE theory" will provide novel insights for future research on NAFLD/NASH.

Patients with hepatocellular carcinoma that die during the first year of liver transplantation have high blood sFasL concentrations

BACKGROUND

Fas ligand (FasL) is one ligand that activates extrinsic apoptosis pathway. High expression in lymphocytes of FasL have been found in patients with acute rejection of liver transplantation (LT). No high blood concentrations of soluble FasL (sFasL) have been found in patients with acute LT rejection; however, the samples size of those studies was small.

AIM

To determine whether patients with hepatocellular carcinoma (HCC) that dead during the first year of LT have higher blood sFasL concentrations previously to LT that those who that remain alive in a study of higher sample size.

METHODS

Patients underwent LT due to HCC were included in this retrospective study. Serum sFasL levels prior to LT were measured and one-year LT mortality was registered.

RESULTS

Non-surviving patients (n = 14) showed higher serum sFasL levels [477 (269-496) vs 85 (44-382) pg/mL; P < 0.001] than surviving patients (n = 113). Serum sFasL levels (pg/mL) were associated with mortality (OR = 1.006; 95%CI = 1.003-1.010; P = 0.001) independently of age of LT donor in the logistic regression analysis.

CONCLUSION

We report for the first time that HCC patients who die within the first year of HT have higher blood sFasL concentrations prior to HT than those who remain alive.

Inflammasome and pyroptosis in autoimmune liver diseases

Autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC), and IgG4-related sclerosing cholangitis (IgG4-SC) are the four main forms of autoimmune liver diseases (AILDs), which are all defined by an aberrant immune system attack on the liver. Most previous studies have shown that apoptosis and necrosis are the two major modes of hepatocyte death in AILDs. Recent studies have reported that inflammasome-mediated pyroptosis is critical for the inflammatory response and severity of liver injury in AILDs. This review summarizes our present understanding of inflammasome activation and function, as well as the connections among inflammasomes, pyroptosis, and AILDs, thus highlighting the shared features across the four disease models and gaps in our knowledge. In addition, we summarize the correlation among NLRP3 inflammasome activation in the liver-gut axis, liver injury, and intestinal barrier disruption in PBC and PSC. We summarize the differences in microbial and metabolic characteristics between PSC and IgG4-SC, and highlight the uniqueness of IgG4-SC. We explore the different roles of NLRP3 in acute and chronic cholestatic liver injury, as well as the complex and controversial crosstalk between various types of cell death in AILDs. We also discuss the most up-to-date developments in inflammasome- and pyroptosis-targeted medicines for autoimmune liver disorders.

Inhibition of VDAC1 Rescues Aβ 1-42-Induced Mitochondrial Dysfunction and Ferroptosis via Activation of AMPK and Wnt/β-Catenin Pathways

Beta-amyloid (Aβ) accumulation in the brains of Alzheimer's disease (AD) patients leads to mitochondrial dysfunction and ferroptosis in neurons. Voltage-dependent anion channel 1 (VDAC1) is a major protein in the mitochondrial outer membrane. It has been reported that VDAC1 associated with mitochondrial dysfunction and ferroptosis. However, the mechanism by which VDAC1 regulates mitochondrial dysfunction and ferroptosis of neurons in AD remains unclear. This study is aimed at investigating the mechanism of action of VDAC1 in mitochondrial dysfunction and ferroptosis in neurons of the AD model. In this study, we determined cell viability after treatment with Aβ _1-42 via the MTT assay. The SOD, MDA, ROS, and MMP production was measured via the SOD kit, MDA kit, DCFDA staining, and JC-1 staining. The memory abilities of mice were detected via the Morris water maze test. The expression of AMPK/mTOR, Wnt/β-catenin, and GPX4 regulated by VDAC1 was detected via western blotting. Our present study showed that PC12 cells had decreased cell viability, increased LDH release, and decreased GPX4 expression after Aβ _1-42 treatment. Meanwhile, Aβ _1-42 induced MMP and SOD downregulation and increased MDA and ROS generation in PC12 cells. In addition, the expression of VDAC1 is increased in the brain tissue of AD mice and Aβ _1-42-treated PC12 cells. Further investigation of the role of VDAC1 in regulating AD found that all effects induced by Aβ _1-42 were reversed by inhibition of VDAC1. Additionally, inhibition of VDAC1 activates the AMPK/mTOR and Wnt/β-catenin pathways. Taken together, these findings demonstrate that inhibition of VDAC1 alleviates mitochondrial dysfunction and ferroptosis in AD neurons by activating AMPK/mTOR and Wnt/β-catenin.

ADP-ribose-acceptor hydrolase 2 ( Arh2 ) deficiency results in cardiac dysfunction, tumorigenesis, inflammation, and decreased survival

ADP-ribosylation is a reversible reaction with ADP-ribosyltransferases catalyzing the forward reaction and ADP-ribose-acceptor hydrolases (ARHs) hydrolyzing the ADP-ribose acceptor bond. ARH2 is a member of the 39-kDa ARH family (ARH1-3), which is expressed in heart and skeletal muscle. ARH2 failed to exhibit any in vitro enzymatic activity. To determine its possible in vivo activities, Arh2 -knockout (KO) and - heterozygous (Het) mice were generated using CRISPR-Cas9. Arh2 -KO mice exhibited decreased cardiac contractility by MRI, echocardiography and dobutamine stress with cardiomegaly and abnormal motor function. Arh2 -Het mice showed results similar to those seen in Arh2 -KO mice except for cardiomegaly. Arh2 -KO and -Het mice and mouse embryonic fibroblasts (MEFs) developed spontaneous tumors and subcutaneous tumors in nude mice. We identified 13 mutations in Arh2 -Het MEFs and heterozygous tumors, corresponding to human ARH2 mutations in cancers obtained from COSMIC. Of interest, the L116R mutation in Arh2 gene plays a critical role in aggressive tumorigenesis in nude mice, corresponding to human ARH2 mutations in stomach adenocarcinoma. Both genders of Arh2 -KO and -Het mice showed increased unexpectedly deaths and decreased survival rate during a 24-month observation, caused by tumor, inflammation, non-inflammation (e.g., cardiomegaly, dental dysplasia), and congenital diseases. Thus, Arh2 plays a pivotal role in cardiac function, tumorigenesis, inflammation, and overall survival.

Neurotensin modulation of lipopolysaccharide induced inflammation of gut-liver axis: Evaluation using neurotensin receptor agonist and antagonist

Lipopolysaccharide (LPS), a toxic component of the cell wall of Gram-negative bacteria, is a potent immune stressor. LPS-induced inflammation of the gut-liver axis is well demonstrated. Neurotensin (NTS), a tri-decapeptide present in the gastrointestinal tract, has anti-inflammatory, anti-oxidative, and growth-promoting properties. This study elucidated the efficacy of PD149163, the type I NTS receptor agonist (NTS₁) in the modulation of LPS-induced inflammation of the gut-liver axis of mice. Young-adult female mice (Age: 8 weeks; BW: 25 ± 2.5 g) were maintained in six groups (6/group); Group I as control and Group II, III & IV were exposed to LPS (1 mg/kg BW/Day; i.p.) for five days. LPS pre-exposed Group III and Group IV mice were treated with NTS₁ agonist PD149163 (100 μg/kg BW i.p.) and antagonist SR48692 (0.5 mg/kg BW i.p.) respectively for 28 days. Group V and Group VI mice were exposed to only PD149163 and only SR48692 respectively with the doses as mentioned above for 28 days. Group I and LPS-exposed Group II mice were also maintained four weeks without further treatment. Histopathology revealed LPS-induced inflammation of the gut and liver. Significant elevation of plasma TNF-α and IL-6 and serum ALT and AST reflected as biomarkers of inflammation. Oxidative stress on both organs was distinct from decreased glutathione reductase and increased lipid peroxidation. PD149163 but not SR48692 ameliorated LPS-induced inflammation in both gut and liver counteracting inflammatory responses and oxidative stress. The use of NTS agonists including PD149163 could be exploited for therapeutic intervention of inflammatory diseases including that of the gut-liver axis.

Programmed cell death and lipid metabolism of macrophages in NAFLD

Non-alcoholic fatty liver disease (NAFLD) has now become the leading chronic liver disease worldwide with lifestyle changes. This may lead to NAFLD becoming the leading cause of end-stage liver disease in the future. To date, there are still no effective therapeutic drugs for NAFLD. An in-depth exploration of the pathogenesis of NAFLD can help to provide a basis for new therapeutic agents or strategies. As the most important immune cells of the liver, macrophages play an important role in the occurrence and development of liver inflammation and are expected to become effective targets for NAFLD treatment. Programmed cell death (PCD) of macrophages plays a regulatory role in phenotypic transformation, and there is also a certain connection between different types of PCD. However, how PCD regulates macrophage polarization has still not been systematically elucidated. Based on the role of lipid metabolic reprogramming in macrophage polarization, PCD may alter the phenotype by regulating lipid metabolism. We reviewed the effects of macrophages on inflammation in NAFLD and changes in their lipid metabolism, as well as the relationship between different types of PCD and lipid metabolism in macrophages. Furthermore, interactions between different types of PCD and potential therapeutic agents targeting of macrophages PCD are also explored.

IL-1β neutralization prevents diastolic dysfunction development, but lacks hepatoprotective effect in an aged mouse model of NASH

Interleukin-1β (IL-1β) is a key mediator of non-alcoholic steatohepatitis (NASH), a chronic liver disease, and of systemic inflammation-driven aging. IL-1β contributes to cardio-metabolic decline, and may promote hepatic oncogenic transformation. Therefore, IL-1β is a potential therapeutic target in these pathologies. We aimed to investigate the hepatic and cardiac effects of an IL-1β targeting monoclonal antibody in an aged mouse model of NASH. 24 months old male C57Bl/6J mice were fed with control or choline deficient (CDAA) diet and were treated with isotype control or anti-IL-1β Mab for 8 weeks. Cardiac functions were assessed by conventional-and 2D speckle tracking echocardiography. Liver samples were analyzed by immunohistochemistry and qRT-PCR. Echocardiography revealed improved cardiac diastolic function in anti-IL-1β treated mice with NASH. Marked hepatic fibrosis developed in CDAA-fed group, but IL-1β inhibition affected fibrosis only at transcriptomic level. Hepatic inflammation was not affected by the IL-1β inhibitor. PCNA staining revealed intensive hepatocyte proliferation in CDAA-fed animals, which was not influenced by neutralization of IL-1β. IL-1β inhibition increased hepatic expression of Pd-1 and Ctla4, while Pd-l1 expression increased in NASH. In conclusion, IL-1β inhibition improved cardiac diastolic function, but did not ameliorate features of NASH; moreover, even promoted hepatic immune checkpoint expression, with concomitant NASH-related hepatocellular proliferation.

Ferroptosis As a Mechanism for Health Effects of Essential Trace Elements and Potentially Toxic Trace Elements

Ferroptosis is a unique form of programmed cell death driven by iron-dependent phospholipid peroxidation that was proposed in recent years. It plays an important role in processes of various trace element-related diseases and is regulated by redox homeostasis and various cellular metabolic pathways (iron, amino acids, lipids, sugars), as well as disease-related signaling pathways. Some limited pioneering studies have demonstrated ferroptosis as a mechanism for the health effects of essential trace elements and potentially toxic trace elements, with crosstalk among them. The aim of this review is to bring together research articles and identify key direct and indirect evidence regarding essential trace elements (iron, selenium, zinc, copper, chromium, manganese) and potentially toxic trace elements (arsenic, aluminum, mercury) and their possible roles in ferroptosis. Our review may help determine future research priorities and opportunities.

Polydeoxyribonucleotide ameliorates alcoholic liver injury though suppressing phosphatidylinositol 3-kinase/protein kinase B signaling pathway in mice

Polydeoxyribonucleotide (PDRN), which is adenosine A_2A receptor agonist, facilitates healing and inhibits inflammation and apoptosis. The effect of PDRN on alcoholic liver injury (ALI) was evaluated focusing on the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway. The mice were given daily oral administration of 50% ethanol at a dose of 4 g/kg during 8 weeks. After 4 weeks of alcohol intake, 200 μL of normal saline containing 8-mg/kg PDRN was intraperitoneally administered 3 times a week for 4 weeks. To determine whether the action of PDRN occurs through the adenosine A_2A receptor, 8-mg/kg 3,7-dimethyl-1-propargylxanthine (DMPX) with PDRN was treated. The concentration of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) was detected. For liver histopathological score, hematoxylin and eosin staining was conducted. Enzyme-linked immunoassay was used to measure cyclic adenosine-3',5'-monophosphate (cAMP) concentration. PI3K and Akt expression was determined using Western blot analysis. In the results, PDRN treatment suppressed AST and ALT level in serum and liver tissue, and improved damaged liver tissue and decreased histological score. PDRN application inhibited the expression of phosphorylated PI3K/Akt signaling pathway. The increasing effect of PDRN on cAMP level ats as a mechanism for ALI treatment. Co-treatment of DMPX with PDRN did not reduce apoptosis, causing no improvement in liver function. As a result of this experiment, PDRN has the potential to be selected as a therapeutic agent for ALI.

Obeticholic acid and ferrostatin-1 differentially ameliorate non-alcoholic steatohepatitis in AMLN diet-fed ob/ob mice

Introduction: Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are common chronic liver diseases with limited treatment options. Methods: Ob/ob mice (6 weeks old) were fed with the Control diet or amylin liver NASH (AMLN) diet for 24 weeks to establish the NASH, the AMLN diet-fed mice were treated with obeticholic acid (OCA), ferrostatin-1 (Fer-1) or their combination for 7 weeks. Finally, various clinical profiles were assessed. Results: Our results indicate that Fer-1 exerts better effects on improving body weight, blood glucose levels, transaminase levels and insulin resistance than OCA. OCA has a profound effect on ameliorating lipid accumulation. OCA and Fer-1 differentially inhibit the activation of hepatic Kupffer cells and HSCs. The combination of OCA and Fer-1 significantly reduces inflammation and protects mice against liver oxidative stress. OCA and Fer-1 differentially reshape the intestinal microbiota and affect the hepatic lipidome. Discussion: Our study compares the effects of OCA, Fer-1 and their combination on various clinical profiles in NASH. These data demonstrate that different drug combinations results in different improvements, and these discoveries provide a reference for the use of the OCA, Fer-1 and their combination in the clinical treatment of NAFLD/NASH.

Regulatory Networks, Management Approaches, and Emerging Treatments of Nonalcoholic Fatty Liver Disease

The pathogenesis of NAFLD is complex and diverse, involving multiple signaling pathways and cytokines from various organs. Hepatokines, stellakines, adipokines, and myokines secreted by hepatocytes, hepatic stellate cells, adipose tissue, and myocytes play an important role in the occurrence and development of nonalcoholic fatty liver disease (NAFLD). The nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) contributes to the progression of NAFLD by mediating liver inflammation, immune response, hepatocyte death, and later compensatory proliferation. In this review, we first discuss the crosstalk and interaction between hepatokines, stellakines, adipokines, and myokines and NF-κB in NAFLD. The characterization of the crosstalk of NF-κB with these factors will provide a better understanding of the molecular mechanisms involved in the progression of NAFLD. In addition, we examine new expert management opinions for NAFLD and explore the therapeutic potential of silymarin in NAFLD/NASH.

Multi-Omics Analysis Reveals the Protection of Gasdermin D in Concanavalin A-Induced Autoimmune Hepatitis

Autoimmune hepatitis (AIH) is a progressive inflammation-associated liver injury. Pyroptosis is a novel inflammatory programmed cell death wherein gasdermin D (GSDMD) serves as the executioner. Our work challenged Gsdmd^-/- mice with concanavalin A (ConA) to try to unveil the actual role of GSDMD in AIH. After ConA injection, Gsdmd^-/- mice exhibited more severe liver damage characterized by a lower survival rate, more extensive hepatocyte necrosis and apoptosis, and higher serum transaminase levels, indicating the protection of GSDMD in ConA-induced AIH. Furthermore, the Gsdmd^-/- mice exhibited higher hepatic expression and serum levels of inflammatory cytokines (gamma interferon [IFN-γ], tumor necrosis factor alpha [TNF-α], and interleukin-17A [IL-17A]) and more infiltration of macrophages and neutrophils after ConA treatment than did wild-type (WT) mice. Gsdmd^-/- mice with AIH showed increased hepatic l-glutamine levels but decreased glycerophospholipid metabolites levels. L-glutamine levels showed positive correlations while glycerophospholipid metabolites showed negative associations with liver injury indexes and inflammation markers. We further observed a destroyed intestinal barrier in Gsdmd^-/- mice after ConA injection as indicated by decreased transcriptional expressions of Tjp1, Ocln, Reg3g, and Muc2. ConA-treated Gsdmd^-/- mice also exhibited higher serum LPS binding protein (LBP) concentrations and hepatic Tlr4 and Cd14 mRNA levels. Further fecal 16S rRNA gene sequencing demonstrated decreased relative abundances of Lactobacillus and Roseburia but increased relative abundances of Allobaculum and Dubosiella in Gsdmd^-/- mice with AIH. Lactobacillus was negatively correlated with liver injury and inflammation indexes and positively associated with Ocln, Muc2, and Reg3g levels. Allobaculum was positively related to liver injury and inflammatory cytokines and negatively correlated with gut barrier indexes. IMPORTANCE Our study provides the first direct clues to the protective role of gasdermin D (GSDMD) in autoimmune hepatitis (AIH). We demonstrated that Gsdmd knockout exacerbated concanavalin A (ConA)-induced AIH in mice. It may be due to the destroyed intestinal barrier and changes in certain intestinal microbes and hepatic metabolites resulting in increased liver injury and inflammation in ConA-treated Gsdmd^-/- mice. This finding suggested a nonnegligible role of GSDMD in AIH and also confirmed its physiological nonpyroptosis effects on the host. The role of GSDMD in autoimmune liver diseases or other liver diseases is complex and intriguing, deserving deep investigation.

Ferroptosis: Shedding Light on Mechanisms and Therapeutic Opportunities in Liver Diseases

Cell death is a vital physiological or pathological phenomenon in the development process of the organism. Ferroptosis is a kind of newly-discovered regulated cell death (RCD), which is different from other RCD patterns, such as apoptosis, necrosis and autophagy at the morphological, biochemical and genetic levels. It is a kind of iron-dependent mode of death mediated by lipid peroxides and lipid reactive oxygen species aggregation. Noteworthily, the number of studies focused on ferroptosis has been increasing exponentially since ferroptosis was first found in 2012. The liver is the organ that stores the most iron in the human body. Recently, it was frequently found that there are different degrees of iron metabolism disorder and lipid peroxidation and other ferroptosis characteristics in various liver diseases. Numerous investigators have discovered that the progression of various liver diseases can be affected via the regulation of ferroptosis, which may provide a potential therapeutic strategy for clinical hepatic diseases. This review aims to summarize the mechanism and update research progress of ferroptosis, so as to provide novel promising directions for the treatment of liver diseases.

Host and immunosuppression-related factors influencing fibrosis occurrence post liver transplantation

Post liver transplantation (LT) fibrosis has a negative impact on graft function. Cytokine production in the host immune response after LT may contribute to the variable CYP3A-dependent immunosuppressive drug disposition, with subsequent impact on liver fibrogenesis, together with host-related factors. We aimed to investigate whether the cytochrome P4503A5*3 (CYP3A5*3) or TBX21 genotypes impact post-LT liver fibrogenesis. Furthermore, the impact of immunosuppressants on cellular apoptosis has been evaluated using human hepatocytes harvested from cirrhotic explanted livers. We have enrolled 98 LT recipients that were followed for occurrence of liver fibrosis for at least 12 months. There was a statistically significant higher trough level of TAC in patients with homozygous CC-TBX21 genotype (7.83 ± 2.84 ng/ml) vs. 5.66 ± 2.16 ng/ml in patients without this genotype (p = 0.009). The following variables were identified as risk factors for fibrosis ≥2: donor age (p = 0.02), neutrophil to lymphocyte ratio (p = 0.04) and TBX21 genotype CC (p = 0.009). In the cell culture model cytometry analysis has indicated the lowest apoptotic cells percentage in human cirrhotic hepatocytes cultures treated with mycophenolate mofetil (MMF) (5%) and TAC + MMF (2%) whereas the highest apoptosis percentage was registered for the TAC alone (11%). The gene expression results are concordant to cytometry study results, indicating the lowest apoptotic effect for MMF and MMF + TAC immunosuppressive regimens. The allele 1993C of the SNP rs4794067 may predispose to the development of late significant fibrosis of the liver graft. MMF-based regimens have a favourable anti-apoptotic profile in vitro, supporting its use in case of LT recipients at high risk for liver graft fibrosis.

Dietary Galla Chinensis tannic acid supplementation in the diets improves growth performance, immune function and liver health status of broiler chicken

This experiment was conducted to investigate the effects of Galla Chinensis tannic acid (TA) on growth performance, immune function, and liver health status in broilers. A total of 288 1-day-old Arbor Acres broiler chickens were randomly divided into two groups in a 42-days study. The two groups were a basal diet (CON group) and a basal diet supplemented with 300 mg/kg Galla Chinensis tannic acid (TA group). The results showed that the TA group had significantly decreased feed-to-gain ratio (F/G) throughout the experiment (P < 0.05). The levels of total protein, albumin, low density lipoprotein, high density lipoprotein, urea, total cholesterol, and glucose in the TA group were significantly higher than in the CON group (P < 0.05). In addition, the serum immunoglobulin G, immunoglobulin M, and complements (C3, C4) levels in the TA group were significantly higher than those in the CON group (P < 0.05). Compared with the CON group, the hepatic interleukin-6, interleukin-18, NLRs family pyrin domain containing 3 (NLRP3), caspase-1, and caspase-3 in the TA group were significantly decreased (P < 0.05). Besides, TA group had significantly lower mRNA expression levels of toll-like receptor 4 (TLR4), myeloid differentiation primary response 88 (MyD88), nuclear factor-kappa B (NF-κB), and NLRP3 in liver (P < 0.05). The TA group had significantly higher the mRNA expression levels of Bcl-2 than CON group in liver (P < 0.05). Moreover, TA group tended to decrease Bax/Bcl-2 ratio in liver (P < 0.10). To sum up, dietary supplemented with microencapsulated TA from Galla Chinensis had beneficial effects on growth performance, immune function, and liver health status in broilers. The protective role of TA from Galla Chinensis in liver health of broilers might be related to the inhibition of hepatic apoptosis and pyroptosis via inactivation of TLR4/MyD88/NF-κB signaling pathway.

Galectin-3 critically mediates the hepatoprotection conferred by M2-like macrophages in ACLF by inhibiting pyroptosis but not necroptosis signalling

We previously documented that M2-like macrophages exert a hepatoprotective effect in acute-on-chronic liver failure (ACLF) by inhibiting necroptosis signalling. Nevertheless, the molecular mechanism behind this hepatoprotection still needs to be further dissected. Galectin-3 (GAL3) has been reported to be critically involved in the pathogenesis of multiple liver diseases, whereas the potential role of GAL3 in ACLF remains to be explored. Herein, we hypothesised that GAL3 plays a pivotal role in the hepatoprotection conferred by M2-like macrophages in ACLF by inhibiting necroptosis. To test this hypothesis, we first assessed the expression of GAL3 in control and fibrotic mice with or without acute insult. Second, loss- and gain-of-function experiments of GAL3 were performed. Third, the correlation between GAL3 and M2-like macrophage activation was analysed, and the potential role of GAL3 in M2-like macrophage-conferred hepatoprotection was confirmed. Finally, the molecular mechanism underlying GAL3-mediated hepatoprotection was dissected. GAL3 was found to be obviously upregulated in fibrotic mice with or without acute insult but not in acutely injured mice. Depletion of GAL3 aggravated hepatic damage in fibrotic mice upon insult. Conversely, adoptive transfer of GAL3 provided normal mice enhanced resistance against acute insult. The expression of GAL3 is closely correlated with M2-like macrophage activation. Through adoptive transfer and depletion experiments, M2-like macrophages were verified to act as a major source of GAL3. Importantly, GAL3 was confirmed to hold a pivotal place in the hepatoprotection conferred by M2-like macrophages through loss- and gain-of-function experiments. Unexpectedly, the depletion and adoptive transfer of GAL3 resulted in significant differences in the expression levels of pyroptosis but not necroptosis signalling molecules. Taken together, GAL3 plays a pivotal role in the hepatoprotection conferred by M2-like macrophages in ACLF by inhibiting pyroptosis but not necroptosis signalling. Our findings provide novel insights into the pathogenesis and therapy of ACLF.

Regulating Nrf2-GPx4 axis by bicyclol can prevent ferroptosis in carbon tetrachloride-induced acute liver injury in mice

Hepatocellular death is a sensitive parameter for detecting acute liver injury (ALI) of toxic, viral, metabolic, and autoimmune origin. Ferroptosis has recently been implicated in carbon tetrachloride (CCl₄)-induced ALI. However, the underpinning mechanism and mechanistic basis remain elusive. In this study, bicyclol, a proprietary hepatoprotectant in China, and ferroptosis-specific inhibitor ferrostatin-1 (Fer-1) were administered in CCl₄-injured mice. A panel of ferroptosis-related markers, including mitochondria morphology, reactive oxygen species production, protein adducts in response to lipid peroxidation, and key modulators of ferroptotic process, was determined in vivo. Erastin-treated L-O2 hepatocytes were transfected with glutathione peroxidase 4 (GPx4) or nuclear factor erythroid 2-related factor 2 (Nrf2) siRNA to delineate the pathway of bicyclol against ferroptosis in vitro. As a result, CCl₄ led to iron accumulation, excessive reactive oxygen species production, enhanced lipid peroxidation, and characteristic morphological changes in mitochondria, along with a decrease in GPx4 and xCT protein levels in ALI mice liver, all of which were generally observed in ferroptosis. The use of Fer-1 further corroborated that ferroptosis is responsible for liver damage. Bicyclol exerted its hepatoprotection by preventing the aforesaid ferroptotic process. Furthermore, bicyclol alleviated erastin-induced cellular inviability, destruction, and lipid peroxidation in vitro. Knockdown of GPx4 diminished these protective activities against perturbations associated with ferroptosis in L-O2 hepatocytes. Additionally, Nrf2 silencing drastically reduced GPx4 levels, and further impeded the medicinal effects of bicyclol. In summary, positively regulating Nrf2-GPx4 axis by bicyclol can prevent ferroptosis in CCl₄-induced ALI in mice.

New insights into the mechanism of alcohol-mediated organ damage via its impact on immunity, metabolism, and repair pathways: A summary of the 2021 Alcohol and Immunology Research Interest Group (AIRIG) meeting

On November 19th, 2021, the annual Alcohol and Immunology Research Interest Group (AIRIG) meeting was held at Loyola University Chicago Health Sciences Campus in Maywood, Illinois. The 2021 meeting focused on how alcohol misuse is linked to immune system derangements, leading to tissue and organ damage, and how this research can be translated into improving treatment of alcohol-related disease. This meeting was divided into three plenary sessions: the first session focused on how alcohol misuse affects different parts of the immune system, the second session presented research on mechanisms of organ damage from alcohol misuse, and the final session highlighted research on potential therapeutic targets for treating alcohol-mediated tissue damage. Diverse areas of alcohol research were covered during the meeting, from alcohol's effect on pulmonary systems and neuroinflammation to epigenetic changes, senescence markers, and microvesicle particles. These presentations yielded a thoughtful discussion on how the findings can lead to therapeutic treatments for people suffering from alcohol-related diseases.

Acrylamide induces ferroptosis in HSC-T6 cells by causing antioxidant imbalance of the XCT-GSH-GPX4 signaling and mitochondrial dysfunction

Acrylamide (AA) is a heat-induced food contaminant, mainly metabolized by the liver. Increasing evidences have proved that ferroptosis is linked to the pathogenesis of liver disease. In the current study, the underlying mechanism of AA-induced rat hepatic stellate (HSC-T6) cells ferroptosis was investigated by detecting changes in iron levels, expressions of ferroptosis-related proteins and indicators of mitochondrial dysfunction. The results showed that AA treatment led to iron levels increased and expressions of long-chain acyl-CoA synthase 4 (ACSL4), cyclooxygenase 2 (COX2) and ferritin heavy chain 1 (FTH1) proteins in HSC-T6 cells were all altered. Treatment with the ferroptosis inhibitor ferrostatin-1 (Fer-1) markedly reversed the impact of AA, suggesting that AA induced ferroptosis in HSC-T6 cells. Mechanistically, AA induced the onset of ferroptosis by affecting XCT-GSH-GPX4 antioxidant signaling. Moreover, AA created a peroxidative environment for ferroptosis by inducing oxidative stress in HSC-T6 cells through mitochondrial dysfunction, as evidenced by increased mitochondrial ROS (mtROS) release, mitochondrial membrane potential (MMP) depolarization, and decreased mitochondrial ATP. Our results indicated that AA resulted in mitochondrial dysfunction and ferroptosis, and dysregulation of XCT-GSH-GPX4 antioxidant signaling was a key factor in AA-induced ferroptosis.

Inflammation aggravated the hepatotoxicity of triptolide by oxidative stress, lipid metabolism disorder, autophagy, and apoptosis in zebrafish

Triptolide is a major compound isolated from the Tripterygium wilfordii Hook that is mainly used for the treatment of autoimmune disorders and inflammatory diseases. Though triptolide-induced hepatotoxicity has been widely reported, the hepatic effects when the patients are in an inflammatory state are not clear. In this study, we used low-dose Lipopolysaccharides (LPS) to disrupt the inflammation homeostasis in the liver of zebrafish and explored the hepatotoxicity of triptolide under an inflammatory state. Compared with the Triptolide group, LPS-Triptolide cotreatment exacerbate the liver injury with a remarkable decrease of liver size and liver-specific fluorescence intensity, accompanied by significant elevation of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities. Liver cell damages were further demonstrated by histological staining and scanning electron microscopy observation. Lipid metabolism was severely impaired as indicated by delayed yolk sac absorption, accumulated triglycerides in the liver, and dysregulation of the related genes, such as ppar-α, cpt-1, mgst, srebf1/2, and fasn. Oxidative stress could be involved in the molecular mechanism as the Nrf2/keap1 antioxidant pathways were down-regulated when the zebrafish in an inflammatory state. Moreover, the expression of autophagy-related genes such as beclin, atg5, map1lc3b, and atg3 was also dysregulated. Finally, apoptosis was significantly induced in responses to LPS-Triptolide co-treatment. We speculate that triptolide could exacerbate the immune response and impair lipid metabolism, resulting in enhanced sensitivity of the zebrafish liver to triptolide-induced toxic effects through disruption of the antioxidant system and induction of apoptosis.

Perspectives and mechanisms for targeting ferroptosis in the treatment of hepatocellular carcinoma

Ferroptosis is a novel process of regulated cell death discovered in recent years, mainly caused by intracellular lipid peroxidation. It is morphologically manifested as shrinking of mitochondria, swelling of cytoplasm and organelles, rupture of plasma membrane, and formation of double-membrane vesicles. Work done in the past 5 years indicates that induction of ferroptosis is a promising strategy in the treatment of hepatocellular carcinoma (HCC). System xc^-/GSH/GPX4, iron metabolism, p53 and lipid peroxidation pathways are the main focus areas in ferroptosis research. In this paper, we analyze the ferroptosis-inducing drugs and experimental agents that have been used in the last 5 years in the treatment of HCC. We summarize four different key molecular mechanisms that induce ferroptosis, i.e., system xc^-/GSH/GPX4, iron metabolism, p53 and lipid peroxidation. Finally, we outline the prognostic analysis associated with ferroptosis in HCC. The findings summarized suggest that ferroptosis induction can serve as a promising new therapeutic approach for HCC and can provide a basis for clinical diagnosis and prevention of this disease.

Targeted therapeutics and novel signaling pathways in non-alcohol-associated fatty liver/steatohepatitis (NAFL/NASH)

Non-alcohol-associated fatty liver/steatohepatitis (NAFL/NASH) has become the leading cause of liver disease worldwide. NASH, an advanced form of NAFL, can be progressive and more susceptible to developing cirrhosis and hepatocellular carcinoma. Currently, lifestyle interventions are the most essential and effective strategies for preventing and controlling NAFL without the development of fibrosis. While there are still limited appropriate drugs specifically to treat NAFL/NASH, growing progress is being seen in elucidating the pathogenesis and identifying therapeutic targets. In this review, we discussed recent developments in etiology and prospective therapeutic targets, as well as pharmacological candidates in pre/clinical trials and patents, with a focus on diabetes, hepatic lipid metabolism, inflammation, and fibrosis. Importantly, growing evidence elucidates that the disruption of the gut-liver axis and microbe-derived metabolites drive the pathogenesis of NAFL/NASH. Extracellular vesicles (EVs) act as a signaling mediator, resulting in lipid accumulation, macrophage and hepatic stellate cell activation, further promoting inflammation and liver fibrosis progression during the development of NAFL/NASH. Targeting gut microbiota or EVs may serve as new strategies for the treatment of NAFL/NASH. Finally, other mechanisms, such as cell therapy and genetic approaches, also have enormous therapeutic potential. Incorporating drugs with different mechanisms and personalized medicine may improve the efficacy to better benefit patients with NAFL/NASH.