Hepatocyte-specific TMEM16A deficiency alleviates hepatic ischemia/reperfusion injury via suppressing GPX4-mediated ferroptosis

Gas6/AXL Alleviates Hepatic Ischemia/Reperfusion Injury by Inhibiting Ferroptosis via the PI3K/AKT Pathway

BACKGROUND

Hepatic ischemia/reperfusion (I/R) injury is a major cause of complications in clinical liver surgery. AXL receptor tyrosine kinase (AXL) is a member of the TAM receptor tyrosine kinase family (TYRO3, AXL, and MERTK). Our previous study has shown that AXL expression was markedly upregulated in liver transplantation patients. However, the underlying mechanism of AXL in hepatic I/R injury remains unclear.

METHODS

A mouse liver warm I/R model and a primary hepatocyte hypoxia/reoxygenation model were established to investigate the role of AXL activation and ferroptosis in hepatic I/R injury by pretreating with recombinant mouse growth arrest-specific protein 6 (AXL activator) or R428 (AXL inhibitor). Moreover, we used LY294002 (phosphatidylinositol 3-kinase [PI3K] inhibitor) to evaluate the relationship between the PI3K/AKT (the Ser and Thr kinase AKT) pathway and ferroptosis in hepatic I/R injury.

RESULTS

Hepatic I/R injury decreased phosphorylation AXL expression and enhanced ferroptosis in liver transplantation patients and hepatic I/R-subjected mice. AXL activation attenuated lipid peroxidation and ferroptosis in hepatic I/R injury in vivo and in vitro. Inhibition of AXL activation exacerbated liver pathological damage and liver dysfunction, as well as iron accumulation and lipid peroxidation in hepatic I/R injury. Mechanistically, activated growth arrest-specific protein 6/AXL and its downstream PI3K/AKT signaling pathway inhibited ferroptosis during hepatic I/R injury.

CONCLUSIONS

AXL activation protects against hepatic I/R injury by preventing ferroptosis through the PI3K/AKT pathway. This study is the first investigation on the AXL receptor and ferroptosis, and activating AXL to mitigate ferroptosis may be an innovative therapeutic strategy to combat hepatic I/R injury.

Mitochondria-Associated Organelle Crosstalk in Myocardial Ischemia/Reperfusion Injury

Organelle damage is a significant contributor to myocardial ischemia/reperfusion (I/R) injury. This damage often leads to disruption of endoplasmic reticulum protein regulatory programs and dysfunction of mitochondrial energy metabolism. Mitochondria and endoplasmic reticulum are seamlessly connected through the mitochondrial-associated endoplasmic reticulum membrane (MAM), which serves as a crucial site for the exchange of organelles and metabolites. However, there is a lack of reports regarding the communication of information and metabolites between mitochondria and related organelles, which is a crucial factor in triggering myocardial I/R damage. To address this research gap, this review described the role of crosstalk between mitochondria and the correlative organelles such as endoplasmic reticulum, lysosomal and nuclei involved in reperfusion injury of the heart. In summary, this review aims to provide a comprehensive understanding of the crosstalk between organelles in myocardial I/R injury, with the ultimate goal of facilitating the development of targeted therapies based on this knowledge.

Genetic and pharmacological targeting of XBP1 alleviates hepatic ischemia reperfusion injury by enhancing FoxO1-dependent mitophagy

Hepatic ischemia reperfusion (I/R) injury is a common clinical complication. X-box binding protein 1 (XBP1), as a critical regulator of the endoplasmic reticulum stress, has been implicated in a variety of diseases. In this study, we aimed to investigate the effects and the underlying mechanism of XBP1 in the progression of hepatic I/R injury. Hepatocyte-specific XBP1 knockout mice, multiple viral delivery systems and specific pharmacological inhibitors were applied in vivo in a partial hepatic I/R injury mouse model and in vitro in a cell model of hypoxia-reoxygenation (H/R) injury. Mitophagy and autophagic flux were evaluated and fluorescence resonance energy transfer (FRET) as well as immunoprecipitation were performed. The results demonstrated that reperfusion for 6 h represented a critical timepoint in hepatic I/R injury and resulted in significant intracellular mitochondrial dysfunction; led to the breakdown of hepatocytes accompanied by the highest expression levels of XBP1. Hepatocyte-specific XBP1 knockout alleviated hepatic I/R injury via enhanced mitophagy, as demonstrated by the reduction in hepatocellular damage/necrosis and increased expression of mitophagy markers. Mechanistically, XBP1 interacted with FoxO1 directly and catalyzed the ubiquitination of FoxO1 for proteasomal degradation. Targeting XBP1 by genetic or pharmacological techniques potentiated the protein levels of FoxO1, further promoting the activity of the PINK1/Parkin signaling pathway, thus augmenting mitophagy and exerting hepatoprotective effects upon I/R injury. In conclusion, the inhibition of XBP1 potentiated FoxO1-mediated mitophagy in hepatic I/R injury. Specific genetic and pharmacological treatment targeting XBP1 in the perioperative 6 h prior to reperfusion exerted beneficial effects, thus providing a novel therapeutic approach.

SYK promotes the formation of neutrophil extracellular traps by inducing PKM2 nuclear translocation and promoting STAT3 phosphorylation to exacerbate hepatic ischemia-reperfusion injury and tumor recurrence

BACKGROUND

At present, hepatic ischemia-reperfusion injury (IRI) is an important complication of partial hepatectomy and liver transplantation, and it is an important cause of poor prognosis. Spleen tyrosine kinase(SYK) plays an important role in a variety of signaling pathways in the liver, but its role in hepatic IRI is still unclear. This study aims to investigate the role and mechanism of SYK in hepatic IRI and tumor recurrence.

METHODS

We first observed the activation of SYK in the liver of mice in response to hepatic IRI. Subsequently, Pharmacological inhibitions of SYK were used to evaluated the effect of SYK on neutrophil recruitment and NETosis, and further explored the effect of SYK on IRI and tumor recurrence.

RESULTS

Our study shows that SYK is activated in response to hepatic IRI and aggravates liver injury. On the one hand, neutrophils SYK during the early stage of liver reperfusion increases neutrophil extracellular traps (NETs) production by promoting Pyruvate kinase M2(PKM2) nuclear translocation leading to upregulation of phosphorylated STAT3, thereby exacerbating liver inflammation and tumor recurrence. On the other hand, macrophages SYK can promote the recruitment of neutrophils and increase the activation of NLRP3 inflammasome and IL1β, which further promotes the formation of NETs.

CONCLUSIONS

Our study demonstrates that neutrophil and macrophage SYK synergistically promote hepatic IRI and tumor recurrence, and SYK may be a potential target to improve postoperative hepatic IRI and tumor recurrence.

Ferroptosis-based advanced therapies as treatment approaches for metabolic and cardiovascular diseases

Ferroptosis has attracted attention throughout the last decade because of its tremendous clinical importance. Here, we review the rapidly growing body of literature on how inhibition of ferroptosis may be harnessed for the treatment of common diseases, and we focus on metabolic and cardiovascular unmet medical needs. We introduce four classes of preclinically established ferroptosis inhibitors (ferrostatins) such as iron chelators, radical trapping agents that function in the cytoplasmic compartment, lipophilic radical trapping antioxidants and ninjurin-1 (NINJ1) specific monoclonal antibodies. In contrast to ferroptosis inducers that cause serious untoward effects such as acute kidney tubular necrosis, the side effect profile of ferrostatins appears to be limited. We also consider ferroptosis as a potential side effect itself when several advanced therapies harnessing small-interfering RNA (siRNA)-based treatment approaches are tested. Importantly, clinical trial design is impeded by the lack of an appropriate biomarker for ferroptosis detection in serum samples or tissue biopsies. However, we discuss favorable clinical scenarios suited for the design of anti-ferroptosis clinical trials to test such first-in-class compounds. We conclude that targeting ferroptosis exhibits outstanding treatment options for metabolic and cardiovascular diseases, but we have only begun to translate this knowledge into clinically relevant applications.

CircRNA-Phf21a_0002 promotes pyroptosis to aggravate hepatic ischemia/ reperfusion injury by sponging let-7b-5p

Hepatic ischemia‒reperfusion injury is a common injury in liver surgery and liver transplantation that can lead to liver function damage, including oxidative stress, apoptosis, autophagy and inflammatory reactions. Pyroptosis is a type of inflammatory programmed cell death that has been implicated in ischemia‒reperfusion injury-associated inflammatory reactions. Although circular RNAs can regulate cell death in hepatic ischemia‒reperfusion injury, their relationship with pyroptosis remains unclear. Therefore, this study aimed to investigate the effect of circular RNA on pyroptosis in hepatic ischemia‒reperfusion injury. We constructed a mouse hepatic ischemia‒reperfusion injury model for circular RNA sequencing and obtained 40 circular RNAs with significant differential expression, of which 39 were upregulated and 1 was downregulated. Subsequently, the endogenous competitive RNA network was constructed using TarBase, miRTarBase, TargetScan, RNAhybrid, and miRanda. Gene Set Enrichment Analysis, Kyoto Encyclopedia of Genes and Genomes and Gene Ontology functional analyses of downstream target genes revealed that circRNA-Phf21a_0002 might affect pyroptosis by regulating the mTOR signaling pathway and Bach1 by sponging let-7b-5p. The overexpression plasmid upregulated the expression of circRNA-Phf21a_0002 in a hypoxia/reoxygenation model, which aggravated pyroptosis in AML12 cells and apoptosis and necrosis of hepatocytes. Next, we investigated the underlying mechanism and found that circRNA-Phf21a_0002 enabled the expression of Bach1 through sponging of let-7b-5p. The aggravation of pyroptosis via overexpression of circRNA-Phf21a_0002 was reversed by let-7b-5p mimics in hypoxia/reoxygenation-subjected AML12 cells. Collectively, our study clarifies that circRNA-Phf21a_0002 aggravates the pyroptosis of hepatocytes related to ischemia-reperfusion by sponging let-7b-5p. These findings provide new molecular mechanisms and novel biomarkers for follow-up treatment.

Exosomes derived from Baicalin-pretreated bone mesenchymal stem cells improve Th17/Treg imbalance after hepatic ischemia-reperfusion via FGF21 and the JAK2/STAT3 pathway

Baicalin is an active compound extracted from Scutellaria baicalensis with antioxidant and anti-inflammatory properties. Bone mesenchymal stem cells (BMSCs)-derived exosomes have shown promise for the treatment of hepatic ischemia-reperfusion (I/R) injury. This study aims to investigate the role of Baicalin-pretreated BMSCs-derived exosomes in hepatic I/R injury and its mechanisms. BMSCs were pretreated with or without Baicalin, and their exosomes (Ba-Exo and Exo) were collected and characterized. These exosomes were administered to mice via tail vein injection. Treatment with Exo and Ba-Exo significantly suppressed the elevation of ALT and AST induced by hepatic injury. Additionally, both Exo and Ba-Exo treatments resulted in a reduction in the liver weight-to-body weight ratio. RT-PCR results revealed a significant downregulation of pro-inflammatory cytokines with Exo and Ba-Exo treatment. Both Exo and Ba-Exo treatment improved the Th17/Treg cell imbalance induced by I/R and reduced hepatic injury. Additionally, exosomes were cocultured with normal liver cells, and the expression of fibroblast growth factor 21 (FGF21) in liver cells was elevated through Ba-Exo treatment. After treatment, the JAK2/STAT3 pathway was inhibited, and FOXO1 expression was upregulated. Finally, recombinant FGF21 was injected into mouse tail veins to assess its effects. Recombinant FGF21 injection further inhibited the JAK2/STAT3 pathway, increased FOXO1 expression, and improved the Th17/Treg cell imbalance. In conclusion, this study confirms the protective effects of Exo and Ba-Exo against hepatic I/R injury. Ba-Exo mitigates hepatic I/R injury, achieved through inducing FGF21 expression in liver cells, inhibiting the JAK2/STAT3 pathway, and activating FOXO1 expression. Therefore, baicalin pretreatment emerges as a promising strategy to enhance the therapeutic capability of BMSCs-derived exosomes for hepatic I/R.

Insights into the function and regulation of the calcium-activated chloride channel TMEM16A

The TMEM16A channel, a member of the TMEM16 protein family comprising chloride (Cl-) channels and lipid scramblases, is activated by the free intracellular Ca2+ increments produced by inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ release after GqPCRs or Ca2+ entry through cationic channels. It is a ubiquitous transmembrane protein that participates in multiple physiological functions essential to mammals' lives. TMEM16A structure contains two identical 10-segment monomers joined at their transmembrane segment 10. Each monomer harbours one independent hourglass-shaped pore gated by Ca2+ ligation to an orthosteric site adjacent to the pore and controlled by two gates. The orthosteric site is created by assembling negatively charged glutamate side chains near the pore´s cytosolic end. When empty, this site generates an electrostatic barrier that controls channel rectification. In addition, an isoleucine-triad forms a hydrophobic gate at the boundary of the cytosolic vestibule and the inner side of the neck. When the cytosolic Ca2+ rises, one or two Ca2+ ions bind to the orthosteric site in a voltage (V)-dependent manner, thus neutralising the electrostatic barrier and triggering an allosteric gating mechanism propagating via transmembrane segment 6 to the hydrophobic gate. These coordinated events lead to pore opening, allowing the Cl- flux to ensure the physiological response. The Ca2+-dependent function of TMEM16A is highly regulated. Anions with higher permeability than Cl- facilitate V dependence by increasing the Ca2+ sensitivity, intracellular protons can replace Ca2+ and induce channel opening, and phosphatidylinositol 4,5-bisphosphate bound to four cytosolic sites likely maintains Ca2+ sensitivity. Additional regulation is afforded by cytosolic proteins, most likely by phosphorylation and protein-protein interaction mechanisms.

TXNIP knockdown ameliorates hepatic ischemia/reperfusion injury by inhibiting apoptosis and improving mitochondrial dysfunction via HIF-1α

This study aims to investigate whether thioredoxin-interacting protein (TXNIP) regulates cell viability, cell apoptosis and mitochondrial damage in OGD/R-induced hepatocytes and to explore its underlying mechanism. AML12 cells were cultured under oxygen-glucose deprivation/reperfusion (OGD/R) conditions. TXNIP mRNA was detected using qRT-PCR, and the TXNIP protein was analyzed using western blotting. TXNIP-targeted short hairpin RNA (sh-TXNIP) lentivirus was used to infect the AML12 cells. CCK8 and TUNEL assays were applied to detect cell viability and apoptosis, respectively. DCFH-DA probe was used to determine reactive oxygen species (ROS) release level, and JC-1 probe was used to evaluate mitochondrial membrane potential (MMP). The localization of TXNIP and HIF-1α was observed using immunofluorescence. Our results showed that TXNIP markedly increased in AML12 cells treated with OGD/R. TXNIP knockdown increased cell viability and reduced cell apoptosis under OGD/R treatment. Moreover, MMP significantly increased and ROS release decreased in cells after TXNIP knockdown under OGD/R treatment. Additionally, TXNIP knockdown markedly increased the expression of HIF-1α. HIF-1α exhibited nuclear translocation following OGD/R induction, and TXNIP knockdown further promoted it. Compared with the OGD/R + sh-TXNIP group, HIF-1α agonist ML228 inhibited cell apoptosis and ROS release, and increased MMP. However, HIF-1α inhibitor PX478 had the opposite effect. In summary, TXNIP deletion ameliorated AML12 cell injury caused by OGD/R via promoting HIF-1α expression and nuclear translocation, manifested by inhibiting cell apoptosis and alleviating mitochondrial dysfunction.

ERRFI1 exacerbates hepatic ischemia reperfusion injury by promoting hepatocyte apoptosis and ferroptosis in a GRB2-dependent manner

BACKGROUND

Programmed cell death is an important mechanism for the development of hepatic ischemia and reperfusion (IR) injury, and multiple novel forms of programmed cell death are involved in the pathological process of hepatic IR. ERRFI1 is involved in the regulation of cell apoptosis in myocardial IR. However, the function of ERRFI1 in hepatic IR injury and its modulation of programmed cell death remain largely unknown.

METHODS

Here, we performed functional and molecular mechanism studies in hepatocyte-specific knockout mice and ERRFI1-silenced hepatocytes to investigate the significance of ERRFI1 in hepatic IR injury. The histological severity of livers, enzyme activities, hepatocyte apoptosis and ferroptosis were determined.

RESULTS

ERRFI1 expression increased in liver tissues from mice with IR injury and hepatocytes under oxygen-glucose deprivation/reoxygenation (OGD/R) conditions. Hepatocyte-specific ERRFI1 knockout alleviated IR-induced liver injury in mice by reducing cell apoptosis and ferroptosis. ERRFI1 knockdown reduced apoptotic and ferroptotic hepatocytes induced by OGD/R. Mechanistically, ERRFI1 interacted with GRB2 to maintain its stability by hindering its proteasomal degradation. Overexpression of GRB2 abrogated the effects of ERRFI1 silencing on hepatocyte apoptosis and ferroptosis.

CONCLUSIONS

Our results revealed that the ERRFI1-GRB2 interaction and GRB2 stability are essential for ERRFI1-regulated hepatic IR injury, indicating that inhibition of ERRFI1 or blockade of the ERRFI1-GRB2 interaction may be potential therapeutic strategies in response to hepatic IR injury.

FTO deficiency in older livers exacerbates ferroptosis during ischaemia/reperfusion injury by upregulating ACSL4 and TFRC

Older livers are more prone to hepatic ischaemia/reperfusion injury (HIRI), which severely limits their utilization in liver transplantation. The potential mechanism remains unclear. Here, we demonstrate older livers exhibit increased ferroptosis during HIRI. Inhibiting ferroptosis significantly attenuates older HIRI phenotypes. Mass spectrometry reveals that fat mass and obesity-associated gene (FTO) expression is downregulated in older livers, especially during HIRI. Overexpressing FTO improves older HIRI phenotypes by inhibiting ferroptosis. Mechanistically, acyl-CoA synthetase long chain family 4 (ACSL4) and transferrin receptor protein 1 (TFRC), two key positive contributors to ferroptosis, are FTO targets. For ameliorative effect, FTO requires the inhibition of Acsl4 and Tfrc mRNA stability in a m6A-dependent manner. Furthermore, we demonstrate nicotinamide mononucleotide can upregulate FTO demethylase activity, suppressing ferroptosis and decreasing older HIRI. Collectively, these findings reveal an FTO-ACSL4/TFRC regulatory pathway that contributes to the pathogenesis of older HIRI, providing insight into the clinical translation of strategies related to the demethylase activity of FTO to improve graft function after older donor liver transplantation.

The role of anoctamin 1 in liver disease

Liver diseases include all types of viral hepatitis, alcoholic liver disease (ALD), nonalcoholic fatty liver disease (NAFLD), cirrhosis, liver failure (LF) and hepatocellular carcinoma (HCC). Liver disease is now one of the leading causes of disease and death worldwide, which compels us to better understand the mechanisms involved in the development of liver diseases. Anoctamin 1 (ANO1), a calcium-activated chloride channel (CaCC), plays an important role in epithelial cell secretion, proliferation and migration. ANO1 plays a key role in transcriptional regulation as well as in many signalling pathways. It is involved in the genesis, development, progression and/or metastasis of several tumours and other diseases including liver diseases. This paper reviews the role and molecular mechanisms of ANO1 in the development of various liver diseases, aiming to provide a reference for further research on the role of ANO1 in liver diseases and to contribute to the improvement of therapeutic strategies for liver diseases by regulating ANO1.

GPX4, ferroptosis, and diseases

GPX4 (Glutathione peroxidase 4) serves as a crucial intracellular regulatory factor, participating in various physiological processes and playing a significant role in maintaining the redox homeostasis within the body. Ferroptosis, a form of iron-dependent non-apoptotic cell death, has gained considerable attention in recent years due to its involvement in multiple pathological processes. GPX4 is closely associated with ferroptosis and functions as the primary inhibitor of this process. Together, GPX4 and ferroptosis contribute to the pathophysiology of several diseases, including sepsis, nervous system diseases, ischemia reperfusion injury, cardiovascular diseases, and cancer. This review comprehensively explores the regulatory roles and impacts of GPX4 and ferroptosis in the development and progression of these diseases, with the aim of providing insights for identifying potential therapeutic strategies in the future.

The Role of Cdo1 in Ferroptosis and Apoptosis in Cancer

Cysteine dioxygenase type 1 (Cdo1) is a tumor suppressor gene. It regulates the metabolism of cysteine, thereby influencing the cellular antioxidative capacity. This function puts Cdo1 in a prominent position to promote ferroptosis and apoptosis. Cdo1 promotes ferroptosis mainly by decreasing the amounts of antioxidants, leading to autoperoxidation of the cell membrane through Fenton reaction. Cdo1 promotes apoptosis mainly through the product of cysteine metabolism, taurine, and low level of antioxidants. Many cancers exhibit altered function of Cdo1, underscoring its crucial role in cancer cell survival. Genetic and epigenetic alterations have been found, with methylation of Cdo1 promoter as the most common mutation. The fact that no cancer was found to be caused by altered Cdo1 function alone indicates that the tumor suppressor role of Cdo1 is mild. By compiling the current knowledge about apoptosis, ferroptosis, and the role of Cdo1, this review suggests possibilities for how the mild anticancer role of Cdo1 could be harnessed in new cancer therapies. Here, developing drugs targeting Cdo1 is considered meaningful in neoadjuvant therapies, for example, helping against the development of anti-cancer drug resistance in tumor cells.

Ferroptosis in liver cancer: a key role of post-translational modifications

Ferroptosis is an emerging form of regulated cell death in an oxidative stress- and iron-dependent manner, primarily induced by the over-production of reactive oxygen species (ROS). Manipulation of ferroptosis has been considered a promising therapeutic approach to inhibit liver tumor growth. Nevertheless, the development of resistance to ferroptosis in liver cancer poses a significant challenge in cancer treatment. Post-translational modifications (PTMs) are crucial enzymatic catalytic reactions that covalently regulate protein conformation, stability and cellular activities. Additionally, PTMs play pivotal roles in various biological processes and divergent programmed cell death, including ferroptosis. Importantly, key PTMs regulators involved in ferroptosis have been identified as potential targets for cancer therapy. PTMs function of two proteins, SLC7A11, GPX4 involved in ferroptosis resistance have been extensively investigated in recent years. This review will summarize the roles of PTMs in ferroptosis-related proteins in hepatocellular carcinoma (HCC) treatment.

A single-chain antibody construct with specificity of a natural IgM antibody reduces hepatic ischemia reperfusion injury in mice

Natural immunoglobulin M (IgM) antibodies have been shown to recognize post-ischemic neoepitopes following reperfusion of tissues and to activate complement. Specifically, IgM antibodies and complement have been shown to drive hepatic ischemia reperfusion injury (IRI). Herein, we investigate the therapeutic effect of C2 scFv (single-chain antibody construct with specificity of a natural IgM antibody) on hepatic IRI in C57BL/6 mice. Compared with PBS-treated mice, C2 scFv-treated mice displayed almost no necrotic areas, significant reduction in serum ALT, AST and LDH levels, and significantly reduced in the number of TUNEL positive cells. Moreover, C2 scFv-treated mice exhibited a notable reduction in inflammatory cells after hepatic IRI than PBS-treated mice. The serum IL-6, IL-1β, TNF-α and MPC-1 levels were also severely suppressed by C2 scFv. Interestingly, C2 scFv reconstituted hepatic inflammation and IRI in Rag1-/- mice. We found that C2 scFv promoted hepatic cell death and increased inflammatory cytokines and infiltration of inflammatory cells after hepatic IRI in Rag1-/- mice. In addition, IgM and complement 3d (C3d) were deposited in WT mice and in Rag1-/- mice reconstituted with C2 scFv, indicating that C2 scFv can affect IgM binding and complement activation and reconstitute hepatic IRI. C3d expression was significantly lower in C57BL/6 mice treated with C2 scFv compared to PBS, indicating that excessive exogenous C2 scFv inhibited complement activation. These data suggest that C2 scFv alleviates hepatic IRI by blocking complement activation, and treatment with C2 scFv may be a promising therapy for hepatic IRI.

Ferroptosis in organ ischemia-reperfusion injuries: recent advancements and strategies

Ferroptosis is a newly discovered type of regulated cell death participated in multiple diseases. Different from other classical cell death programs such as necrosis and apoptosis, ferroptosis involving iron-catalyzed lipid peroxidation is characterized by Fe2+ accumulation and mitochondria alterations. The phenomenon of oxidative stress following organ ischemia-reperfusion (I/R) has recently garnered attention for its connection to the onset of ferroptosis and subsequent reperfusion injuries. This article provides a comprehensive overview underlying the mechanisms of ferroptosis, with a further focus on the latest research progress regarding interference with ferroptotic pathways in organ I/R injuries, such as intestine, lung, heart, kidney, liver, and brain. Understanding the links between ferroptosis and I/R injury may inform potential therapeutic strategies and targeted agents.

Isosteviol plays a protective role on hepatic ischemia and reperfusion injury in mice through MAPK/NF-κB signaling pathway

Background

Hepatic ischemia and reperfusion (I/R) injury is of common occurrence during liver surgery and transplantation, isosteviol (ISV) is an acid hydrolysate of stevioside, the major component of Stevia rebaudiana. Stevioside and its metabolites have been shown to have varieties of pharmacological activities, However, the effect of ISV on hepatic I/R injury has not determined. The purpose of this paper is to study the effect of ISV on mice with hepatic I/R injury and further investigate its underlying mechanism.

Methods

The blood vessels supplying the left/middle lobe of the liver in mice were clamped to cause liver ischemia for 1h, and then removed the clamp to conduct reperfusion for 6 h. ISV or saline was injected intraperitoneally after reperfusion. The expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and IL-10 in serum and tissues were evaluated by enzyme linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction (qRT-PCR). The infiltration of neutrophils and macrophages into the liver tissue was determined by flow cytometry and myeloperoxidase. Liver hematoxylin-eosin (HE) staining, terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling (TUNEL) and Annexin V probe were used to determine liver injury and hepatocyte apoptosis. western blots (WB) was used to investigate the activation of nuclear factor kappa-B (NF-κB) and c-JunNH2 terminal kinase (JNK), p38 and extracellular regulated protein kinase (ERK), while the expression of apoptosis-related proteins B-cell lymphoma-2 (BCL-2), BCL2-associated X protein (BAX), caspase-3 was detected.

Results

ISV reduced aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels to alleviate liver injury. ISV significantly reduced the release of inflammatory cytokines and the accumulation of liver neutrophils and macrophages. Meanwhile, ISV can promote the expression of anti-apoptosis-related protein BCL-2 and inhibit the expression of pro-apoptotic protein BAX and the activation of the protease caspase-3, and reduce the occurrence of hepatocyte apoptosis. Finally, ISV can reduce the phosphorylation level and activation of NF-κB, JNK, p38 and ERK.

Conclusions

ISV inhibits the occurrence of inflammation and hepatocyte apoptosis through mitogen-activated protein kinase (MAPK)/NF-κB signaling pathway to relieve liver injury.

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.

Targeting epigenetic and posttranslational modifications regulating ferroptosis for the treatment of diseases

Ferroptosis, a unique modality of cell death with mechanistic and morphological differences from other cell death modes, plays a pivotal role in regulating tumorigenesis and offers a new opportunity for modulating anticancer drug resistance. Aberrant epigenetic modifications and posttranslational modifications (PTMs) promote anticancer drug resistance, cancer progression, and metastasis. Accumulating studies indicate that epigenetic modifications can transcriptionally and translationally determine cancer cell vulnerability to ferroptosis and that ferroptosis functions as a driver in nervous system diseases (NSDs), cardiovascular diseases (CVDs), liver diseases, lung diseases, and kidney diseases. In this review, we first summarize the core molecular mechanisms of ferroptosis. Then, the roles of epigenetic processes, including histone PTMs, DNA methylation, and noncoding RNA regulation and PTMs, such as phosphorylation, ubiquitination, SUMOylation, acetylation, methylation, and ADP-ribosylation, are concisely discussed. The roles of epigenetic modifications and PTMs in ferroptosis regulation in the genesis of diseases, including cancers, NSD, CVDs, liver diseases, lung diseases, and kidney diseases, as well as the application of epigenetic and PTM modulators in the therapy of these diseases, are then discussed in detail. Elucidating the mechanisms of ferroptosis regulation mediated by epigenetic modifications and PTMs in cancer and other diseases will facilitate the development of promising combination therapeutic regimens containing epigenetic or PTM-targeting agents and ferroptosis inducers that can be used to overcome chemotherapeutic resistance in cancer and could be used to prevent other diseases. In addition, these mechanisms highlight potential therapeutic approaches to overcome chemoresistance in cancer or halt the genesis of other diseases.

Redox regulation of the NLRP3-mediated inflammation and pyroptosis

The review considers modern data on the mechanisms of activation and redox regulation of the NLRP3 inflammasome and gasdermins, as well as the role of selenium in these processes. Activation of the inflammasome and pyroptosis represent an evolutionarily conserved mechanism of the defense against pathogens, described for various types of cells and tissues (macrophages and monocytes, microglial cells and astrocytes, podocytes and parenchymal cells of the kidneys, periodontal tissues, osteoclasts and osteoblasts, as well as cells of the digestive and urogenital systems, etc.). Depending on the characteristics of redox regulation, the participants of NLRP3 inflammation and pyroptosis can be subdivided into 2 groups. Members of the first group block the mitochondrial electron transport chain, promote the formation of reactive oxygen species and the development of oxidative stress. This group includes granzymes, the mitochondrial antiviral signaling protein MAVS, and others. The second group includes thioredoxin interacting protein (TXNIP), erythroid-derived nuclear factor-2 (NRF2), Kelch-like ECH-associated protein 1 (Keap1), ninjurin (Ninj1), scramblase (TMEM16), inflammasome regulatory protein kinase NLRP3 (NEK7), caspase-1, gasdermins GSDM B, D and others. They have redox-sensitive domains and/or cysteine residues subjected to redox regulation, glutathionylation/deglutathionylation or other types of regulation. Suppression of oxidative stress and redox regulation of participants in NLRP3 inflammation and pyroptosis depends on the activity of the antioxidant enzymes glutathione peroxidase (GPX) and thioredoxin reductase (TRXR), containing a selenocysteine residue Sec in the active site. The expression of GPX and TRXR is regulated by NRF2 and depends on the concentration of selenium in the blood. Selenium deficiency causes ineffective translation of the Sec UGA codon, translation termination, and, consequently, synthesis of inactive selenoproteins, which can cause various types of programmed cell death: apoptosis of nerve cells and sperm, necroptosis of erythrocyte precursors, pyroptosis of infected myeloid cells, ferroptosis of T- and B-lymphocytes, kidney and pancreatic cells. In addition, suboptimal selenium concentrations in the blood (0.86 μM or 68 μg/l or less) have a significant impact on expression of more than two hundred and fifty genes as compared to the optimal selenium concentration (1.43 μM or 113 μg/l). Based on the above, we propose to consider blood selenium concentrations as an important parameter of redox homeostasis in the cell. Suboptimal blood selenium concentrations (or selenium deficiency states) should be used for assessment of the risk of developing inflammatory processes.

TMEM16A deficiency in alveolar type 2 epithelial cells protected against endoplasmic reticulum stress-induced ferroptosis during acute lung injury

Transmembrane protein 16A (TMEM16A) is one of the members of the ten-member family of "transmembrane protein 16", playing critical roles in infection and solid organ injury. Acute lung injury (ALI) is a devastating disease which could be triggered by sepsis, trauma, and ischemia reperfusion. However, molecular mechanisms contributing to ALI are poorly understood at presently. In this study, we investigated the role of TMEM16A in sepsis-induced ALI using TMEM16A-deficient mice. Sepsis-induced ALI model was established by intratracheal injection of lipopolysaccharide (LPS). Our results showed that LPS stimulation significantly upregulated the expression levels of TMEM16A in lung tissues and in alveolar epithelial type II (AT2) cells. Knockout of TMEM16A in AT2 cells significantly improved pulmonary function and alleviated lung pathological injury in LPS-treated mice. Meanwhile, TMEM16A deficiency also inhibited endoplasmic reticulum (ER) stress and ferroptosis in AT2 cells from LPS-treated mice. In vitro experiments further demonstrated that ER stress and ferroptosis were inhibited after TMEM16A was knocked out. Furthermore, we used ER stress inducer thapsigargin to induce ER stress in TMEM16A-null AT2 cells and found that the induction of ER stress abolished the inhibition of ferroptosis by TMEM16A deficiency in LPS-treated AT2 cells. Finally, we disclosed that pharmacological inhibition of TMEM16A by shikonin also showed similar therapeutic effect on LPS-induced ALI in vivo. In conclusion, TMEM16A deficiency in AT2 cells could alleviate sepsis-induced ALI by decreasing ER stress-induced ferroptosis during ALI.

The ubiquitin-proteasome system links NADPH metabolism to ferroptosis

Ferroptosis is the type of cell death arising from uncontrolled and excessive lipid peroxidation. NADPH is essential for ferroptosis regulation because it supplies reducing equivalents for antioxidant defense systems and contributes to the generation of reactive oxygen species. Moreover, NADPH level serves as a biomarker for predicting the sensitivity of cells to ferroptosis. The ubiquitin-proteasome system governs the stability of many ferroptosis effectors. Recent research has revealed MARCHF6, the endoplasmic reticulum ubiquitin ligase, as an unprecedented NADPH sensor in the ubiquitin system and a critical regulator of ferroptosis involved in tumorigenesis and fetal development. This review summarizes the current understanding of NADPH metabolism and the ubiquitin-proteasome system in regulating ferroptosis and highlights the emerging importance of MARCHF6 as a vital connector between NADPH metabolism and ferroptosis.

Ferroptosis in the post-transplantation inflammatory response

Transplantation is a life-saving therapy for patients with end-stage organ disease. Successful outcomes after transplantation require mitigation of the post-transplant inflammatory response, limiting alloreactivity, and prevention of organ rejection. Traditional immunosuppressive regimens aim to dampen the adaptive immune response; however, recent studies have shown the feasibility and efficacy of targeting the innate immune response. Necroinflammation initiated by donor organ cell death is implicated as a critical mediator of primary graft dysfunction, acute rejection, and chronic rejection. Ferroptosis is a form of regulated cell death that triggers post-transplantation inflammation and drives the activation of both innate and adaptive immune cells. There is a growing acceptance of the clinical relevance of ferroptosis to solid organ transplantation. Modulating ferroptosis may be a potentially promising strategy to reduce complications after organ transplantation.

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.

Transaldolase inhibits CD36 expression by modulating glutathione-p38 signaling, exerting protective effects against macrophage foam cell formation

In atherosclerosis, macrophage-derived foam cell formation is considered to be a hallmark of the pathological process; this occurs via the uptake of modified lipoproteins. In the present study, we aim to determine the role of transaldolase in foam cell formation and atherogenesis and reveal the mechanisms underlying its role. Bone marrow-derived macrophages (BMDMs) isolated from mice successfully form foam cells after treatment with oxidized low-density lipoprotein (80 μg/mL). Elevated transaldolase levels in the foam cell model are assessed by quantitative polymerase chain reaction and western blot analysis. Transaldolase overexpression and knockdown in BMDMs are achieved via plasmid transfection and small interfering RNA technology, respectively. We find that transaldolase overexpression effectively attenuates, whereas transaldolase knockdown accelerates, macrophage-derived foam cell formation through the inhibition or activation of cholesterol uptake mediated by the scavenger receptor cluster of differentiation 36 (CD36) in a p38 mitogen-activated protein kinase (MAPK) signaling-dependent manner. Transaldolase-mediated glutathione (GSH) homeostasis is identified as the upstream regulator of p38 MAPK-mediated CD36-dependent cholesterol uptake in BMDMs. Transaldolase upregulates GSH production, thereby suppressing p38 activity and reducing the CD36 level, ultimately preventing foam cell formation and atherosclerosis. Thus, our findings indicate that the transaldolase-GSH-p38-CD36 axis may represent a promising therapeutic target for atherosclerosis.

Molecular mechanisms of ferroptosis and its antitumor applications in natural products

Ferroptosis, an iron-dependent form of regulated cell death, results in lipid peroxidation of polyunsaturated fatty acids in the cell membrane, which is catalyzed by iron ions and accumulated to lethal levels. It is mechanistically distinct from other forms of cell death, such as apoptosis, pyroptosis, and necroptosis, so it may address the problem of cancer resistance to apoptosis and provide new therapeutic strategies for cancer treatment, which has been intensively studied over the past few years. Notably, considerable advances have been made in the antitumor research of natural products due to their multitargets and few side effects. According to research, natural products can also induce ferroptosis in cancer therapies. In this review we summarize the molecular mechanisms of ferroptosis, introduce the key regulatory genes of ferroptosis, and discuss the progress of natural product research in the field of ferroptosis to provide theoretical guidance for research on natural product-induced ferroptosis in tumors.

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.

Ferroptosis Regulated by Hypoxia in Cells

Ferroptosis is an oxidative damage-related, iron-dependent regulated cell death with intracellular lipid peroxide accumulation, which is associated with many physiological and pathological processes. It exhibits unique features that are morphologically, biochemically, and immunologically distinct from other regulated cell death forms. Ferroptosis is regulated by iron metabolism, lipid metabolism, anti-oxidant defense systems, as well as various signal pathways. Hypoxia, which is found in a group of physiological and pathological conditions, can affect multiple cellular functions by activation of the hypoxia-inducible factor (HIF) signaling and other mechanisms. Emerging evidence demonstrated that hypoxia regulates ferroptosis in certain cell types and conditions. In this review, we summarize the basic mechanisms and regulations of ferroptosis and hypoxia, as well as the regulation of ferroptosis by hypoxia in physiological and pathological conditions, which may contribute to the numerous diseases therapies.