Decreased autophagosome biogenesis, reduced NRF2, and enhanced ferroptotic cell death are underlying molecular mechanisms of non-alcoholic fatty liver disease

ELANE enhances KEAP1 protein stability and reduces NRF2-mediated ferroptosis inhibition in metabolic dysfunction-associated fatty liver disease

Neutrophil elastase (Elane) is upregulated in metabolic-associated fatty liver disease (MAFLD) and has the capacity to promote disease progression. However, the mechanism by which Elane promotes MAFLD development remains unclear. Ferroptosis, which is an iron-dependent nonapoptotic form of cell death characterized by the iron-induced accumulation of lipid reactive oxygen species (ROS), has been recently considered as an important mechanism for the development of MAFLD. In this study, we used mice of Elane-knockout (Elane-KO) and wild-type (WT), and their primary mouse hepatocytes to establish MAFLD models in vivo and vitro for elucidating the role of Elane in ferroptosis of hepatocytes and MAFLD development. Elane-KO in vivo reduced high-fat diet (HFD) induced hepatic lipid peroxidation levels and the proportion of hepatocyte death, upregulated the expression of Nrf2 and Gpx4, and downregulated Keap1 expression. Treatment with recombinant Elane increased the lipid peroxidation level of hepatocytes, increased the ferroptosis rate of hepatocytes, upregulated the expression of Keap1, enhanced the ubiquitination of Nrf2, and downregulated the expression of Nrf2 and Gpx4 in an FFA-induced MAFLD in vitro model. However, primary hepatocytes from Elane-KO mice presented opposite changes. Furthermore, an in vitro experiment revealed that Elane enhanced the protein stability of Keap1 and thus increased Keap1 expression in hepatocytes by inhibiting the lysosomal degradation of the Keap1 protein. Finally, in vitro Co-IP experiments revealed that Elane increased the protein stability of Keap1 by weakening the binding between P62 and Keap1 and ultimately promoted hepatocyte Nrf2 ubiquitination and ferroptosis in MAFLD. In conclusion, our results suggested that Elane promoted hepatocyte ferroptosis in MAFLD through the P62-Keap1-Nrf2-Gpx4 axis. Elane promotes ferroptosis in hepatocytes from fatty livers. Elane reduces the binding of P62 to Keap1, thereby increasing Keap1 protein stability and subsequently inhibiting the Nrf2/Gpx4 pathway, ultimately leading to ferroptosis in hepatocytes.

Pharmacological targeting of the mitochondrial phosphatase PTPMT1 sensitizes hepatocellular carcinoma to ferroptosis

Protein tyrosine phosphatase mitochondrial 1 (PTPMT1), is a member of the protein tyrosine phosphatase superfamily localized on the mitochondrial inner membrane, and regulates the biosynthesis of cardiolipin. Given the important position of PTPMT1 in mitochondrial function and metabolism, pharmacological targeting of PTPMT1 is considered a promising manner in disease treatments. In this study, we mainly investigated the role of PTPMT1 in hepatocellular carcinoma (HCC) ferroptosis, a new type of cell death accompanied by significant iron accumulation and lipid peroxidation. Herein, the pharmacological inhibition of PTPMT1 was induced by alexidine dihydrochloride (AD, a dibiguanide compound). Human HCC cell lines with PTPMT1 knockout and PTPMT1 overexpression were established using CRISPR/Cas9 and lentiviral transduction methods, respectively. The position of PTPMT1 in regulating HCC ferroptosis was evaluated in vitro and in vivo. Our results indicated that pharmacological inhibition of PTPMT1, facilitated by AD treatment, heightens the susceptibility of HCC to cystine deprivation-ferroptosis, and AD treatment promoted the conversion from ferritin-bound Fe3+ to free Fe2+, which contributed to the labile iron pool in cytoplasm. Meanwhile, pharmacological inhibition of PTPMT1 also induced the formation of both swollen mitochondria and donut mitochondria, and enhanced the metabolism process form succinate to fumarate in mitochondrial tricarboxylic acid (TCA) cycle, which increased the sensitivity of HCC cells to cystine deprivation-induced ferroptosis. In total, our work reveals the close association of PTPMT1 with cysteine deprivation-induced ferroptosis, providing a novel insight into chemotherapy strategies against human HCC.

Thirty years of NRF2: advances and therapeutic challenges

Over the last 30 years, NRF2 has evolved from being recognized as a transcription factor primarily involved in redox balance and detoxification to a well-appreciated master regulator of cellular proteostasis, metabolism and iron homeostasis. NRF2 plays a pivotal role in diverse pathologies, including cancer, and metabolic, inflammatory and neurodegenerative disorders. It exhibits a Janus-faced duality, safeguarding cellular integrity in normal cells against environmental insults to prevent disease onset, whereas in certain cancers, constitutively elevated NRF2 levels provide a tumour survival advantage, promoting progression, therapy resistance and metastasis. Advances in understanding the mechanistic regulation of NRF2 and its roles in human pathology have propelled the investigation of NRF2-targeted therapeutic strategies. This Review dissects the mechanistic intricacies of NRF2 signalling, its cross-talk with biological processes and its far-reaching implications for health and disease, highlighting key discoveries that have shaped innovative therapeutic approaches targeting NRF2.

Hepatic Deletion of Carbohydrate Response Element Binding Protein Impairs Hepatocarcinogenesis in a High-Fat Diet-Induced Mouse Model

The transcription factor carbohydrate response element binding protein (ChREBP) has emerged as a crucial regulator of hepatic glucose and lipid metabolism. The increased ChREBP activity involves the pro-oncogenic PI3K/AKT/mTOR signaling pathway that induces aberrant lipogenesis, thereby promoting hepatocellular carcinomas (HCC). However, the molecular pathogenesis of ChREBP-related hepatocarcinogenesis remains unexplored in the high-fat diet (HFD)-induced mouse model. Male C57BL/6J (WT) and liver-specific (L)-ChREBP-KO mice were maintained on either a HFD or a control diet for 12, 24, and 48 weeks, starting at the age of 4 weeks. At the end of the feeding period, mice were perfused, and liver tissues were formalin-fixed, paraffin-embedded, sectioned, and stained for histological and immunohistochemical analysis. Biochemical and gene expression analysis were conducted using serum and frozen liver tissue. Mice fed with HFD showed a significant increase (p < 0.05) in body weight from 8 weeks onwards compared to the control. WT and L-ChREBP-KO mice also demonstrated a significant increase (p < 0.05) in liver-to-body weight ratio in the 48-week HFD group. HFD mice exhibited a gradual rise in hepatic lipid accumulation over time, with 24-week mice showing a 20-30% increase in fat content, which further advanced to 80-100% fat accumulation at 48 weeks. Both dietary source and the increased expression of lipogenic pathways at transcriptional and protein levels induced steatosis and steatohepatitis in the HFD group. Moreover, WT mice on a HFD exhibited markedly higher inflammation compared to the L-ChREBP-KO mice. The enhanced lipogenesis, glycolysis, persistent inflammation, and activation of the AKT/mTOR pathway collectively resulted in significant metabolic disturbances, thereby promoting HCC development and progression in WT mice. In contrast, hepatic loss of ChREBP resulted in reduced hepatocyte proliferation in the HFD group, which significantly contributed to the impaired hepatocarcinogenesis and a reduced HCC occurrence in the L-ChREBP-KO mice. Our present study implicates that prolonged HFD feeding contributes to NAFLD/NASH, which in turn progresses to HCC development in WT mice. Collectively, hepatic ChREBP deletion ameliorates hepatic inflammation and metabolic alterations, thereby impairing NASH-driven hepatocarcinogenesis.

Gaudichaudione H Enhances the Sensitivity of Hepatocellular Carcinoma Cells to Disulfidptosis via Regulating NRF2-SLC7A11 Signaling Pathway

Gaudichaudione H (GH) is a naturally occurring small molecular compound derived from Garcinia oligantha Merr. (Clusiaceae), but the full pharmacological functions remain unclear. Herein, the potential of GH in disulfidptosis regulation, a novel form of programmed cell death induced by disulfide stress is explored. The omics results indicated that NRF2 signaling could be significantly activated by GH. The potential targets are associated with hepatocarcinogenesis and cell death. Moreover, both glutathione (GSH) metabolism and NADP+-NADPH metabolism are affected by GH, indicating the potential in disulfidptosis regulation. It is also observed that GH enhanced the sensitivity of hepatocellular carcinoma (HCC) cells to disulfidptosis, which is dependent on the activation of NRF2-SLC7A11 pathway. GH significantly increased the levels of NRF2 and promoted the transcription of NRF2 target gene, SLC7A11, through autophagy-mediated non-canonical mechanism. Under the condition of glucose starvation, GH-induced upregulation of SLC7A11 aggravated uptake of cysteine, disturbance of GSH synthesis, depletion of NADPH, and accumulation of disulfide molecules, ultimately leading to the formation of disulfide bonds between different cytoskeleton proteins and disulfidptosis eventually. Collectively, the findings underscore the potential role of GH in promoting cancer cell disulfidptosis, thereby offering a promising avenue for the treatment of drug-resistant HCC in clinical settings.

The Role of Mitochondrial Quality Control in Liver Diseases: Dawn of a Therapeutic Era

The liver is a vital metabolic organ that detoxifies substances, produces bile, stores nutrients, and regulates versatile metabolic processes. Maintaining normal liver cell function requires the prompt and delicate modulation of mitochondrial quality control (MQC), which encompasses a spectrum of processes such as mitochondrial fission, fusion, biogenesis, and mitophagy. Recent studies have shown that disruptions to this homeostatic status are closely linked to the advent and progression of a variety of acute and chronic liver diseases, including but not limited to alcohol-associated liver disease and metabolic dysfunction-associated fatty liver disease. However, the explicit mechanisms by which mitochondrial dysfunction impacts inflammatory pathways and cell death in the context of liver diseases remain unclear. In this narrative review, we provide a detailed description of MQC, analyze the mechanisms underpinning mitochondrial dysfunction induced by different detrimental insults, and further elucidate how imbalanced/disrupted MQC promotes the progression and aggravation of liver diseases, ultimately shedding light on the mitochondrion-centric therapeutic strategies for these pathophysiological entities.

Hinokitiol ameliorates MASH in mice by therapeutic targeting of hepatic Nrf2 and inhibiting hepatocyte ferroptosis

BACKGROUND

Metabolic dysfunction-associated steatohepatitis (MASH), an advanced stage of metabolic dysfunction-associated steatotic liver disease (MASLD), still lacks approved effective clinical drugs. Ferroptosis, a form of regulated cell death driven by excessive iron accumulation and uncontrollable lipid peroxidation, has been proven to be a trigger of inflammation and initiation of steatohepatitis. The pathogenic interplay is modulated by oxidative stress, while the Nrf2-mediated antioxidant response plays a regulatory role in ferroptosis. Phytochemical hinokitiol (Hino) has demonstrated positive efficacy in hepatocellular carcinoma (HCC) in the reported work, but it remains unknown whether its therapeutic effect attributes to delaying the progress of steatohepatitis to HCC.

PURPOSE

This work aimed to systemically investigate the significance of ferroptosis in the pathogenesis of MASH and to demonstrate that Hino, a bioactive monoterpene compound, attenuates the primary pathological characteristics of MASH via promotion of Nrf2/GPX4 signaling.

METHODS

In this work, a MASH model was established using the high-fat/high-cholesterol (HFHC) diet-fed in vivo and palmitic acid/oleic acid (PO)-stimulated hepatocytes in vitro. Biochemical indexes, pathological analysis, western blot, PCR assay, energy metabolic phenotype, molecular docking, and confirmatory assays were performed comprehensively to reveal the key link between the Nrf2/GPX4 axis and the treatment of MASH.

RESULTS

Under MASH conditions with increased oxidative stress, we show that Nrf2 was remarkable downregulated in HFHC diet-fed mice and PO-managed hepatocytes. Mechanistically, hepatic upregulation of Nrf2 through phytochemical Hino supplementation inhibited ferroptosis, enhanced lipid metabolism, and thereby alleviated hepatic steatosis, inflammation, and fibrosis. Conversely, silencing Nrf2 in hepatocytes further promoted the accumulation of key markers of ferroptosis and aggravated MASH phenotypes.

CONCLUSION

Increased ferroptosis promoted steatosis which further drove inflammation and hepatic fibrosis. Our results suggested the significance of Nrf2 in ameliorating MASH, which was regulated through Hino. Thus, targeted inhibition of ferroptosis through Hino administration is a feasible and effective approach for treating MASH.

Temsirolimus inhibits FSP1 enzyme activity to induce ferroptosis and restrain liver cancer progression

Ferroptosis is a non-apoptotic mode of cell death characterized by iron-dependent accumulation of lipid peroxidation. While lipid radical elimination reaction catalyzed by glutathione peroxidase 4 (GPX4) is a major anti-ferroptosis mechanism, inhibiting this pathway pharmaceutically shows promise as an antitumor strategy. However, certain tumor cells exhibit redundancy in lipid radical elimination pathways, rendering them unresponsive to GPX4 inhibitors. In this study, we conducted screens across different cancer cell lines and Food and Drug Administration-approved drugs, leading to the identification of temsirolimus in combination with the GPX4 inhibitor RSL3 as a potent inducer of ferroptosis in liver cancer cells. Mechanistically, temsirolimus sensitized liver cancer cells to ferroptosis by directly binding to and inhibiting ferroptosis suppressor protein 1 (FSP1) enzyme. Notably, while temsirolimus is recognized as a potent mammalian target of rapamycin (mTOR) inhibitor, its ferroptosis-inducing effect is primarily attributed to the inhibition of FSP1 rather than mTOR activity. By employing in vitro colony formation assays and in vivo tumor xenograft models, we demonstrated that the combination of temsirolimus and RSL3 effectively suppressed liver tumor progression. This tumoricidal effect was associated with increased lipid peroxidation and induction of ferroptosis. In conclusion, our findings underscore the potential of combining multitarget ferroptosis-inducing agents to circumvent the resistance to ferroptosis of liver cancer cells and highlight temsirolimus as a promising FSP1 inhibitor and ferroptosis inducer, which also deserves further investigation in translational medicine.

A novel small molecule NJH-13 induces pyroptosis via the Ca2+ driven AKT-FOXO1-GSDME signaling pathway in NSCLC by targeting TRPV5

INTRODUCTION

Pyroptosis represents a mode of programmed necrotic cell death (PCD), mediated by members of gasdermin family (GSDMs), such as GSDME. It is emerging as a promising approach for combating cancer. Notably, GSDME is the key modulator for the switch between apoptosis and pyroptosis in cells. However, GSDME is often downregulated in many malignancies, including lung adenocarcinoma.

OBJECTIVE

To identify novel pyroptosis inducers in non-small cell lung cancer (NSCLC) and dissect the underlying mechanism.

METHODS

Pyroptosis was examined by live cell imaging, PI/Hoechst/Annexin V staining, LDH release assay, ELISA, and western blot assays. DARTS, CETSA, molecular docking was used to identify the target of NJH-13. RNA-seq, qPCR, chromatin immunoprecipitation (ChIP), dual luciferase assays were used elucidate the mechanism.

RESULTS

In this study, NJH-13, an N-containing heterocycle, was screened out and identified to possess the ability to activate GSDME, consequently triggering pyroptosis in NSCLC cells. By using the DARTS strategy, transient receptor potential cation channel subfamily V member 5 (TRPV5) was identified as a potential target of NJH-13. NJH-13 increased intracellular calcium level and triggered oxidative stress, both of which are critical events leading to pyroptosis mediated by GSDME. Mechanistically, NJH-13 enhanced the transcription of GSDME via the protein kinase B (AKT)/forkhead box transcription factor O1 (FOXO1) signaling pathway. ChIP revealed that FOXO1 bound directly to the promoter region of GSDME, thus triggering the GSDME-mediated pyroptosis. Pharmacological and genetic activation of AKT or inhibition of FOXO1 partially rescued NJH-13-induced pyroptotic cell death. Moreover, NJH-13 treatment suppressed tumor growth in vivo.

CONCLUSION

Taken together, our results revealed that TRPV5 is a distinctive target for manipulating pyroptosis and provided evidence that NJH-13 functions as a potential anti-cancer agent capable of triggering pyroptosis in NSCLC cells.

Thiostrepton: multifaceted biological activities and its applications in treatment of inflammatory diseases

Thiostrepton (TST) is a naturally occurring oligopeptide antibiotic with a demonstrated capacity to antagonize a broad spectrum of Gram-positive bacteria. It has been utilized as a safe antimicrobial agent in veterinary medicine. Despite its therapeutic potential, the clinical application of TST has been constrained by its poor solubility and bioavailability. However, an increasing number of studies indicate that TST possesses diverse pharmacological activities, including its significant role in microbe resistance and cancer countering. Notably, recent studies have pointed out that TST also possesses anti-inflammatory potential. It has exhibited promising therapeutic efficacy across various in vivo and in vitro disease models, including non-alcoholic fatty liver disease, inflammatory bowel disease, sepsis, psoriasis-like inflammation, and periodontitis. In this review, we describe the various pharmacological activities of TST, particularly its anti-inflammatory activity demonstrated in a variety of inflammatory diseases and the underlying mechanisms. These effects highlight the potential of TST as an anti-inflammatory agent for the treatment of inflammation diseases and for enhancing cellular therapies.

Vitamin D supplementation alleviates high fat diet-induced metabolic associated fatty liver disease by inhibiting ferroptosis pathway

PURPOSE

Recently, a significant negative correlation has been found between vitamin D (VD) and metabolic associated fatty liver disease (MAFLD), suggesting a potential beneficial role of VD in preventing of MAFLD, while underscoring the importance of exploring its mechanisms.

METHODS

The experiment comprised two parts: male C57BL/6J mice (6 weeks) were fed a high-fat diet (HFD) and intraperitoneally injected with vitamin D3 (VD3) (1.68 IU/g/week) for 16 weeks. Meanwhile, palmitic acid (PA)-induced HepG2 cells were treated with 1,25(OH)2D3 (10 nM). The general conditions of the mice were evaluated by measuring body weight, liver/body weight, serum biochemical parameters, and inflammation indices. Additionally, injury-associated indices and histopathology were used to assess the severity of liver injury. Furthermore, indicators of ferroptosis, including lipid peroxidation, iron aggregation, and the aberrant expression of related proteins, were determined using Prussian blue staining, ELISA assay, and Western blot.

RESULTS

Long-term VD3 administration significantly reduced body weight gain and the liver/body weight ratio of HFD-induced MAFLD mice, while also improving serum lipid metabolism dysregulation and enhancing insulin sensitivity. The changes in the expressions of liver injury indices and histological manifestations due to VD3 treatment indicated that VD3 may exerts beneficial effects on liver injury through inhibiting inflammatory cell infiltration and vacuolation. Importantly, VD3 supplementation also inhibited ferroptosis by enhancing the body's antioxidant capacity, reducing local iron aggregation, and modulating the expression levels of ferroptosis-related proteins. These findings were further confirmed in a PA-induced HepG2 steatosis cell model, highlighting the pharmacological effects of VD.

CONCLUSIONS

VD shows promise in mitigating HFD -induced liver injury by improving metabolic dysregulation and inhibiting ferroptosis, suggesting therapeutic potential in MAFLD.

Bibliometric analysis of autophagy in NAFLD from 2004 to 2023

BACKGROUND

Autophagy is a cellular process in which damaged organelles or unnecessary proteins are encapsulated into double-membrane structures and transported to lysosomes for degradation. Autophagy plays a crucial role in various liver diseases, including nonalcoholic fatty liver disease. This study aims to elucidate the role of autophagy in nonalcoholic fatty liver disease through bibliometric analysis.

METHODS

Literature was retrieved from Web of Science CoreCollection database, and the search time was from January 01, 2004 to December 31, 2023. Data retrieval was performed using the Bibliometrix package in R software. VOSviewer and CiteSpace were utilized to visualize the research hotspots and trends related to the effect of autophagy on nonalcoholic fatty liver disease.

RESULTS

A total of 966 papers were obtained, published in 343 journals from 1385 institutions across 57 countries. The journals with the most publications were the "International Journal of Molecular Sciences" and "Scientific Reports." China had the highest number of published papers. The most productive authors were Yen Paul M and Jung Tae Woo, while Singh R was the most frequently co-cited author. Emerging research hotspots were associated with keywords such as insulin resistance, ferroptosis, endoplasmic reticulum stress, and mitochondrial function.

CONCLUSION

Research on autophagy in nonalcoholic fatty liver disease is still in its early stages, with a growing body of literature. This study is the first to provide a comprehensive bibliometric analysis, synthesizing research trends and advancements. It identifies current development trends, global cooperation models, foundational knowledge, research hotspots, and emerging frontiers in the field.

High-fat diet led to testicular inflammation and ferroptosis via dysbiosis of gut microbes

The disorder of gut microbiota has negative impact on male reproductive, and testicular damage is associated with obesity. However, the detailed mechanism of gut microbiota on the obesity-induced testis injury are still unknown. Therefore, we constructed a mouse model to investigate the effects of obesity on testis injury. In this study, we found that HFD-induced obesity could disorder gut microbiota homeostasis, which increased the abundance of Brevundimonas, Desulfovibrionaceae_unclassified and Ralstonia, ultimately leading to the overproduction of lipopolysaccharides (LPS). Meanwhile, HFD-feeding promoted intestinal permeability via inhibiting expression of tight junction proteins (ZO-1, Occludin and Claudin) and reducing excretion of mucus, leading to translocation of LPS. The over-accumulation of LPS in the bloodstream triggered an inflammatory response by activating TLR4/NF-κB pathway in testis. On the other hand, the gut microbiota produced-LPS also could induce ferroptosis in testis, as reflected by enhancing iron content and lipid peroxidation (MDA), as well as decreasing ferroptosis-related proteins, including GPX4, FTH1 and SLC1A11. Moreover, inhibition of LPS ligand (TLR4) with Resatorvid (TAK-242) alleviated obesity-induced testis injury through suppression of inflammation and ferroptosis. In conclusion, this study provides novel insights into the underlying mechanisms of obesity-related testis injury induced by gut microbiota disorder via the gut-testis axis, thus offering potential targets to counteract obesity-induced male reproductive disorder.

The plant extract PNS mitigates atherosclerosis via promoting Nrf2-mediated inhibition of ferroptosis through reducing USP2-mediated Keap1 deubiquitination

BACKGROUND AND PURPOSE

Atherosclerosis is the basis of cardiovascular disease. Ferroptosis is a form of programmed cell death characterized by lipid peroxidation, which contributes to atherogenesis. The plant extract PNS (Panax notoginseng saponins), containing the main active ingredients of Panax notoginseng, exhibits anti-atherogenic properties. Herein, we determined whether PNS and its major components could attenuate atherosclerosis by suppressing ferroptosis and revealed the underlying mechanism(s).

EXPERIMENTAL APPROACH

The anti-atherogenic effects of PNS and their association with inhibition of ferroptosis was determined in apoE-/- mice. In vitro, the anti-ferroptotic effect and mechanism(s) of PNS components were demonstrated in the presence of ferroptosis inducers. Expression of ferroptosis markers and the ubiquitination of Keap1 were evaluated in USP2-/- macrophages. Finally, the anti-atherogenic effect of USP2 knockout was determined by using USP2-/- mice treated with high-fat diet (HFD) and AAV-PCSK9.

KEY RESULTS

PNS inhibited ferroptosis and atherosclerosis in vivo. PNS suppressed ferroptosis and ferroptosis-aggravated foam cell formation and inflammation in vitro. Mechanistically, PNS and its components activated Nrf2 by antagonizing Keap1, which was attributed to the inhibition of USP2 expression. USP2 knockout antagonized ferroptosis and ferroptosis-aggravated foam cell formation and inflammation, thus mitigating atherosclerosis. USP2 knockout abolished inhibitory effects of PNS on foam cell formation and inflammation in vitro.

CONCLUSION AND IMPLICATIONS

PNS reduced USP2-mediated Keap1 de-ubiquitination and promoted Keap1 degradation, thereby activating Nrf2, improving iron metabolism and reducing lipid peroxidation, thus contributing to an anti-atherosclerotic outcome. Our study revealed the mechanism(s) underlying inhibition of ferroptosis and atherosclerosis by PNS.

Protocatechuic acid relieves ferroptosis in hepatic lipotoxicity and steatosis via regulating NRF2 signaling pathway

Ferroptosis represents a newly programmed cell death, and the process is usually accompanied with iron-dependent lipid peroxidation. Importantly, ferroptosis is implicated in a myriad of diseases. Recent literature suggests a potential position of ferroptosis in the pathogenesis of metabolic dysfunction-associated fatty liver disease (MAFLD), the most widespread liver ailment worldwide. Intriguingly, several functional genes and metabolic pathways central to ferroptosis are regulated by nuclear factor erythroid-derived 2-like 2 (NRF2). In current work, we aim to identify protocatechuic acid (PCA), a primary metabolite of antioxidant polyphenols, as a potent NRF2 activator and ferroptosis inhibitor in the hepatic lipotoxicity and steatosis models. Herein, both NRF2+/+ and NRF2-/- cell lines and mice were used to analyze the importance of NRF2 in PCA function, and hepatic lipotoxicity and steatosis models were induced by palmitic acid and high-fat diet respectively. Our results indicated that ferroptosis was mitigated by PCA intervention in hepatic cells. Furthermore, PCA exhibited therapeutic efficacy against ferroptosis, as well as hepatic lipotoxicity and steatosis. The protective role of PCA was predominantly mediated through NRF2 activation, potentially elucidating a pivotal mechanism underlying PCA's therapeutic impact on MAFLD. Additionally, the augmented mitochondrial TCA cycle activity observed in hepatic lipotoxicity and steatosis models was ameliorated by PCA, in part via NRF2-dependent pathways, further bolstering PCA's anti-ferroptosis properties. Collectively, our findings underscore PCA's potential in alleviating hepatic ferroptosis, lipotoxicity and steatosis via inducing activation of NRF2 signaling pathway, offering a promising strategy for the therapy of MAFLD as well as related lipid metabolic disorders.

The Crosstalk between Autophagy and Nrf2 Signaling in Cancer: from Biology to Clinical Applications

Autophagy is a catabolic process that has been conserved throughout evolution, serving to degrade and recycle cellular components and damaged organelles. Autophagy is activated under various stress conditions, such as nutrient deprivation, viral infections, and genotoxic stress, and operates in conjunction with other stress response pathways to mitigate oxidative damage and maintain cellular homeostasis. One such pathway is the Nrf2-Keap1-ARE signaling axis, which functions as an intrinsic antioxidant defense mechanism and has been implicated in cancer chemoprevention, tumor progression, and drug resistance. Recent research has identified a link between impaired autophagy, mediated by the autophagy receptor protein p62, and the activation of the Nrf2 pathway. Specifically, p62 facilitates Keap1 degradation through selective autophagy, leading to the translocation of Nrf2 into the nucleus, where it transcriptionally activates downstream antioxidant enzyme expression, thus safeguarding cells from oxidative stress. Furthermore, Nrf2 regulates p62 transcription, so a positive feedback loop involving p62, Keap1, and Nrf2 is established, which amplifies the protective effects on cells. This paper aims to provide a comprehensive review of the roles of Nrf2 and autophagy in cancer progression, the regulatory interactions between the Nrf2 pathway and autophagy, and the potential applications of the Nrf2-autophagy signaling axis in cancer therapy.

Gaudichaudione H ameliorates liver fibrosis and inflammation by targeting NRF2 signaling pathway

Gaudichaudione H (GH) is a natural small molecular compound isolated from Garcinia oligantha Merr. (Clusiaceae). Being an uncommon rare caged polyprenylated xanthone, the potential pharmacological functions of GH remain to be fully elucidated currently. In this study, we primarily focused on identifying potential bioavailable targets and elucidating related therapeutic actions. Herein, the network pharmacology analysis, metabolomics analysis and genome-wide mRNA transcription assay were performed firstly to predict the major pharmacological action and potential targets of GH. To confirm the hypothesis, gene knockout model was created using CRISPR/Cas9 method. The pharmacological action of GH was evaluated in vitro and in vivo. Firstly, our results of network pharmacology analysis and omics assay indicated that GH significantly activated NRF2 signaling pathway, and the function could be associated with liver disease treatment. Then, the pharmacological action of GH was evaluated in vitro and in vivo. The treatment with GH significantly increased the protein levels of NRF2 and promoted the transcription of NRF2 downstream genes. Further analysis suggested that GH regulated NRF2 through an autophagy-mediated non-canonical mechanism. Additionally, the administration of GH effectively protected the liver from carbon tetrachloride (CCl4)-induced liver fibrosis and inflammation, which depended on the activation of NRF2 in hepatic stellate cells and inflammatory cells respectively. Collectively, our findings underscore the potential therapeutic effect of GH on alleviating hepatic fibrosis and inflammation through the augmentation of NRF2 signaling pathway, providing a promising avenue for the treatment of liver fibrosis and inflammation in clinical settings.

tBHQ mitigates fatty liver ischemia-reperfusion injury by activating Nrf2 to attenuate hepatocyte mitochondrial damage and macrophage STING activation

BACKGROUND

Liver ischemia-reperfusion (IR) injury is an inevitable pathophysiological process in various liver surgeries. Previous studies have found that IR injury is exacerbated in fatty liver due to significant hepatocellular damage and macrophage inflammatory activation, though the underlying mechanisms are not fully understood. In this study, we aim to explore the role and mechanism of Nrf2 (Nuclear factor erythroid 2-related factor 2) signaling in regulating hepatocellular damage and macrophage immune response in fatty liver IR injury.

METHODS

The study used high-fat diet-induced fatty liver mice to establish an IR model, alongside an in vitro co-culture system of primary hepatocytes and macrophages. This approach was used to examine mitochondrial dysfunction, oxidative stress, mitochondrial DNA (mtDNA) release, and activation of macrophage STING (Stimulator of interferon genes) signaling. We also conducted recovery verification using H-151 (a STING inhibitor) and tBHQ (an Nrf2 activator).

RESULTS

Compared to the control group, mice on a high-fat diet demonstrated more severe liver IR injury, as evidenced by increased histological damage, elevated liver enzyme levels, and heightened inflammatory markers. The HFD group showed significant oxidative stress and mitochondrial dysfunction and damage post-IR, as indicated by elevated levels of ROS and lipid peroxidation markers, and decreased antioxidant enzyme activity. Elevated mtDNA release from hepatocytes post-IR activated macrophage STING signaling, worsening inflammation and liver damage. However, STING signaling inhibition with H-151 in vivo or employing STING knockout macrophages significantly reduced these injuries. In-depth mechanism studies have found that the transfer of Nrf2 protein into the nucleus of liver cells after IR in fatty liver is reduced. Pre-treatment with tBHQ ameliorated liver oxidative stress, mitochondrial damage and suppressed the macrophage STING signaling activation.

CONCLUSIONS

Our study reveals a novel mechanism where the interaction between hepatocellular damage and macrophage inflammation intensifies liver IR injury in fatty liver. Enhancing Nrf2 activation to protect mitochondrial from oxidative stress damage and inhibiting macrophage STING signaling activation emerge as promising strategies for clinical intervention in fatty liver IR injury.

Ferroptosis at the nexus of metabolism and metabolic diseases

Ferroptosis, an iron-dependent form of regulated cell death, is emerging as a crucial regulator of human physiology and pathology. Increasing evidence showcases a reciprocal relationship between ferroptosis and dysregulated metabolism, propagating a pathogenic vicious cycle that exacerbates pathology and human diseases, particularly metabolic disorders. Consequently, there is a rapidly growing interest in developing ferroptosis-based therapeutics. Therefore, a comprehensive understanding of the intricate interplay between ferroptosis and metabolism could provide an invaluable resource for mechanistic insight and therapeutic development. In this review, we summarize the important metabolic substances and associated pathways in ferroptosis initiation and progression, outline the cascade responses of ferroptosis in disease development, overview the roles and mechanisms of ferroptosis in metabolic diseases, introduce the methods for ferroptosis detection, and discuss the therapeutic perspectives of ferroptosis, which collectively aim to illustrate a comprehensive view of ferroptosis in basic, translational, and clinical science.

Nobiletin restores HFD-induced enteric nerve injury by regulating enteric glial activation and the GDNF/AKT/FOXO3a/P21 pathway

BACKGROUND

To explore whether nobiletin has a protective effect on high-fat diet (HFD)-induced enteric nerve injury and its underlying mechanism.

METHODS

An obesity model was induced by a HFD. Nobiletin (100 mg/kg and 200 mg/kg) and vehicle were administered by gastric gavage for 4 weeks. Lee's index, body weight, OGTT and intestinal propulsion assays were performed before sacrifice. After sampling, lipids were detected using Bodipy 493/503; lipid peroxidation was detected using MDA and SOD kits and the expression of PGP 9.5, Trem2, GFAP, β-tubulin 3, Bax, Bcl2, Nestin, P75 NTR, SOX10 and EDU was detected using immunofluorescence. The GDNF, p-AKT, AKT, p-FOXO3a, FOXO3a and P21 proteins were detected using western blotting. The relative mRNA expression levels of NOS2 were detected via qPCR. Primary enteric neural stem cells (ENSCs) were cultured. After ENSCs were treated with palmitic acid (PA) and nobiletin, CCK-8 and caspase-3/7 activity assays were performed to evaluate proliferation and apoptosis.

RESULTS

HFD consumption caused colon lipid accumulation and peroxidation, induced enteric nerve damage and caused intestinal motor dysfunction. However, nobiletin reduced lipid accumulation and peroxidation in the colon; promoted Trem2, β-tubulin 3, Nestin, P75NTR, SOX10 and Bcl2 expression; inhibited Bax and GFAP expression; reduced NOS2 mRNA transcription; and regulated the GDNF/AKT/FOXO3a/P21 pathway. Nobiletin also promoted PA-induced impairment of ENSCs.

CONCLUSIONS

Nobiletin restored HFD-induced enteric nerve injury, which may be associated with inhibiting enteric nerve apoptosis, promoting enteric nerve survival and regulating the GDNF/AKT/FOXO3a/P21 pathway.

Targeting the regulation of iron homeostasis as a potential therapeutic strategy for nonalcoholic fatty liver disease

With aging and the increasing incidence of obesity, nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease worldwide. NAFLD mainly includes simple hepatic steatosis, nonalcoholic steatohepatitis (NASH), liver fibrosis and hepatocellular carcinoma (HCC). An imbalance in hepatic iron homeostasis is usually associated with the progression of NAFLD and induces iron overload, reactive oxygen species (ROS) production, and lipid peroxide accumulation, which leads to ferroptosis. Ferroptosis is a unique type of programmed cell death (PCD) that is characterized by iron dependence, ROS production and lipid peroxidation. The ferroptosis inhibition systems involved in NAFLD include the solute carrier family 7 member 11 (SLC7A11)/glutathione (GSH)/glutathione peroxidase 4 (GPX4) and ferroptosis suppressor protein 1 (FSP1)/coenzyme Q10 (CoQ10)/nicotinamide adenine dinucleotide phosphate (NADPH) regulatory axes. The main promotion system involved is the acyl-CoA synthetase long-chain family (ACSL4)/arachidonic lipoxygenase 15 (ALOX15) axis. In recent years, an increasing number of studies have focused on the multiple roles of iron homeostasis imbalance and ferroptosis in the progression of NAFLD. This review highlights the latest studies about iron homeostasis imbalance- and ferroptosis-associated NAFLD, mainly including the physiology and pathophysiology of hepatic iron metabolism, hepatic iron homeostasis imbalance during the development of NAFLD, and key regulatory molecules and roles of hepatic ferroptosis in NAFLD. This review aims to provide innovative therapeutic strategies for NAFLD.

BACH1 inhibits senescence, obesity, and short lifespan by ferroptotic FGF21 secretion

Ferroptosis is a type of regulated cell death characterized by iron-dependent lipid peroxidation. A model cell system is constructed to induce ferroptosis by re-expressing the transcription factor BACH1, a potent ferroptosis inducer, in immortalized mouse embryonic fibroblasts (iMEFs). The transfer of the culture supernatant from ferroptotic iMEFs activates the proliferation of hepatoma cells and other fibroblasts and suppresses cellular senescence-like features. The BACH1-dependent secretion of the longevity factor FGF21 is increased in ferroptotic iMEFs. The anti-senescent effects of the culture supernatant from these iMEFs are abrogated by Fgf21 knockout. BACH1 activates the transcription of Fgf21 by promoting ferroptotic stress and increases FGF21 protein expression by suppressing its autophagic degradation through transcriptional Sqstm1 and Lamp2 repression. The BACH1-induced ferroptotic FGF21 secretion suppresses obesity in high-fat diet-fed mice and the short lifespan of progeria mice. The inhibition of these aging-related phenotypes can be physiologically significant regarding ferroptosis.

PIM1 alleviated liver oxidative stress and NAFLD by regulating the NRF2/HO-1/NQO1 pathway

AIMS

Non-alcoholic fatty liver disease (NAFLD) has risen as a significant global public health issue, for which vertical sleeve gastrectomy (VSG) has become an effective treatment method. The study sought to elucidate the processes through which PIM1 mitigates the advancement of NAFLD. The Pro-viral integration site for Moloney murine leukemia virus 1 (PIM1) functions as a serine/threonine kinase. Bioinformatics analysis revealed that reduced PIM1 expression in NAFLD.

METHODS

To further prove the role of PIM1 in NAFLD, an in-depth in vivo experiment was performed, in which male C57BL/6 mice were randomly grouped to receive a normal or high-fat diet for 24 weeks. They were operated or delivered the loaded adeno-associated virus which the PIM1 was overexpressed (AAV-PIM1). In an in vitro experiment, AML12 cells were treated with palmitic acid to induce hepatic steatosis.

KEY FINDINGS

The results revealed that the VSG surgery and virus delivery of mice alleviated oxidative stress, and apoptosis in vivo. For AML12 cells, the levels of oxidative stress, apoptosis, and lipid metabolism were reduced via PIM1 upregulation. Moreover, ML385 treatment resulted in the downregulation of the NRF2/HO-1/NQO1 signaling cascade, indicating that PIM1 mitigates NAFLD by targeting this pathway.

SIGNIFICANCE

PIM1 alleviated mice liver oxidative stress and NAFLD induced by high-fat diet by regulating the NRF2/HO-1/NQO1 signaling Pathway.

Sulforaphane prevents diabetes-induced hepatic ferroptosis by activating Nrf2 signaling axis

Recently, we characterized the ferroptotic phenotype in the liver of diabetic mice and revealed nuclear factor (erythroid-derived-2)-related factor 2 (Nrf2) inactivation as an integral part of hepatic injury. Here, we aim to investigate whether sulforaphane, an Nrf2 activator and antioxidant, prevents diabetes-induced hepatic ferroptosis and the mechanisms involved. Male C57BL/6 mice were divided into four groups: control (vehicle-treated), diabetic (streptozotocin-induced; 40 mg/kg, from Days 1 to 5), diabetic sulforaphane-treated (2.5 mg/kg from Days 1 to 42) and non-diabetic sulforaphane-treated group (2.5 mg/kg from Days 1 to 42). Results showed that diabetes-induced inactivation of Nrf2 and decreased expression of its downstream antiferroptotic molecules critical for antioxidative defense (catalase, superoxide dismutases, thioredoxin reductase), iron metabolism (ferritin heavy chain (FTH1), ferroportin 1), glutathione (GSH) synthesis (cystine-glutamate antiporter system, cystathionase, glutamate-cysteine ligase catalitic subunit, glutamate-cysteine ligase modifier subunit, glutathione synthetase), and GSH recycling - glutathione reductase (GR) were reversed/increased by sulforaphane treatment. In addition, we found that the ferroptotic phenotype in diabetic liver is associated with increased ferritinophagy and decreased FTH1 immunopositivity. The antiferroptotic effect of sulforaphane was further evidenced through the increased level of GSH, decreased accumulation of labile iron and lipid peroxides (4-hydroxy-2-nonenal, lipofuscin), decreased ferritinophagy and liver damage (decreased fibrosis, alanine aminotransferase, and aspartate aminotransferase). Finally, diabetes-induced increase in serum glucose and triglyceride level was significantly reduced by sulforaphane. Regardless of the fact that this study is limited by the use of one model of experimentally induced diabetes, the results obtained demonstrate for the first time that sulforaphane prevents diabetes-induced hepatic ferroptosis in vivo through the activation of Nrf2 signaling pathways. This nominates sulforaphane as a promising phytopharmaceutical for the prevention/alleviation of ferroptosis in diabetes-related pathologies.

Updated mechanisms of MASLD pathogenesis

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

Dietary habits in adult Japanese patients with vitiligo

Vitiligo is an autoimmune skin disease with acquired depigmentation. Dietary habits may modulate the pathogenesis of vitiligo. We evaluated dietary habits in adult Japanese patients with nonsegmental vitiligo, and compared their results with those of age- and sex-matched controls. We also examined the relationship between dietary habits and Vitiligo Area Scoring Index (VASI), or vitiligo on different anatomical sites. The intakes of energy, nutrients, and foods in the participants were analyzed using a brief-type self-administered diet history questionnaire. Patients with vitiligo showed higher body mass index (BMI) and lower intakes of manganese, vitamin D, pulses, and confection, compared with controls. Multivariate logistic regression analysis showed that vitiligo was associated with high BMI. VASI was higher in males than in females, and negatively correlated with age or intakes of potatoes and vegetables other than green/yellow vegetables. Linear multivariate regression analysis showed that high VASI was associated with younger age. Multivariate logistic regression analysis showed that moderate to severe vitiligo (VASI ≥ 4.25) was associated with male sex and longer disease duration. Multivariate logistic regression analyses showed the following association with vitiligo on respective anatomical sites: high intake of eggs and dairy products and high VASI on the head or neck, high intake of oils and fats and high VASI on the trunk, high intake of cereals and high VASI on the upper limbs, male sex and high VASI on the lower limbs, and high BMI and high VASI on the hands or feet. In conclusion, the control of obesity might have prophylactic or therapeutic effects on vitiligo.

Insights on E1-like enzyme ATG7: functional regulation and relationships with aging-related diseases

Autophagy is a dynamic self-renovation biological process that maintains cell homeostasis and is responsible for the quality control of proteins, organelles, and energy metabolism. The E1-like ubiquitin-activating enzyme autophagy-related gene 7 (ATG7) is a critical factor that initiates classic autophagy reactions by promoting the formation and extension of autophagosome membranes. Recent studies have identified the key functions of ATG7 in regulating the cell cycle, apoptosis, and metabolism associated with the occurrence and development of multiple diseases. This review summarizes how ATG7 is precisely programmed by genetic, transcriptional, and epigenetic modifications in cells and the relationship between ATG7 and aging-related diseases.

Mechanisms of ferroptosis in nonalcoholic fatty liver disease and therapeutic effects of traditional Chinese medicine: a review

Nonalcoholic fatty liver disease (NAFLD) is characterized by excessive accumulation of fat in hepatocytes (nonalcoholic fatty liver (NAFL)), and lobular inflammation and hepatocyte damage (which characterize nonalcoholic steatohepatitis (NASH) are found in most patients). A subset of patients will gradually develop liver fibrosis, cirrhosis, and eventually hepatocellular carcinoma, which is a deadly disease that threatens human life worldwide. Ferroptosis, a novel nonapoptotic form of programmed cell death (PCD) characterized by iron-dependent accumulation of reactive oxygen radicals and lipid peroxides, is closely related to NAFLD. Traditional Chinese medicine (TCM) has unique advantages in the prevention and treatment of NAFLD due to its multicomponent, multipathway and multitarget characteristics. In this review, we discuss the effect of TCM on NAFLD by regulating ferroptosis, in order to provide reference for the further development and application of therapeutic drugs to treat NAFLD.

Fluoride exposure confers NRF2 activation in hepatocyte through both canonical and non-canonical signaling pathways

Due to the high abundance in the Earth's crust and industrial application, fluoride is widely present in our living environment. However, excessive fluoride exposure causes toxicity in different organs. As the most important detoxification and excretion organ, liver is more easily involved in fluoride toxicity than other organs, and oxidative stress is considered as the key mechanism related with fluoride hepatotoxicity. In this study, we mainly investigated the role of nuclear factor erythroid-derived 2-like 2 (NRF2, a core transcription factor in oxidative stress) in fluoride exposure-induced hepatotoxicity as well as the related mechanism. Herein, liver cells (BNL CL.2) were treated with fluoride in different concentrations. The hepatotoxicity and NRF2 signaling pathway were analyzed respectively. Our results indicated that excessive fluoride (over 1 mM) resulted in obvious toxicity in hepatocyte and activated NRF2 and NRF2 target genes. The increased ROS generation after fluoride exposure suppressed KEAP1-induced NRF2 ubiquitylation and degradation. Meanwhile, fluoride exposure also led to blockage of autophagic flux and upregulation of p62, which contributed to activation of NRF2 via competitive binding with KEAP1. Both pharmaceutical activation and genetic activation of NRF2 accelerated fluoride exposure-induced hepatotoxicity. Thus, the upregulation of NRF2 in hepatocyte after fluoride exposure can be regarded as a cellular self-defense, and NRF2-KEAP1 system could be a novel molecular target against fluoride exposure-induced hepatotoxicity.

Metabolic dysfunction-associated steatotic liver disease: ferroptosis related mechanisms and potential drugs

Metabolic dysfunction-associated steatotic liver disease (MASLD) is considered a "multisystem" disease that simultaneously suffers from metabolic diseases and hepatic steatosis. Some may develop into liver fibrosis, cirrhosis, and even hepatocellular carcinoma. Given the close connection between metabolic diseases and fatty liver, it is urgent to identify drugs that can control metabolic diseases and fatty liver as a whole and delay disease progression. Ferroptosis, characterized by iron overload and lipid peroxidation resulting from abnormal iron metabolism, is a programmed cell death mechanism. It is an important pathogenic mechanism in metabolic diseases or fatty liver, and may become a key direction for improving MASLD. In this article, we have summarized the physiological and pathological mechanisms of iron metabolism and ferroptosis, as well as the connections established between metabolic diseases and fatty liver through ferroptosis. We have also summarized MASLD therapeutic drugs and potential active substances targeting ferroptosis, in order to provide readers with new insights. At the same time, in future clinical trials involving subjects with MASLD (especially with the intervention of the therapeutic drugs), the detection of serum iron metabolism levels and ferroptosis markers in patients should be increased to further explore the efficacy of potential drugs on ferroptosis.

A state-of-the-art review on the NRF2 in Hepatitis virus-associated liver cancer

According to a paper released and submitted to WHO by IARC scientists, there would be 905,700 new cases of liver cancer diagnosed globally in 2020, with 830,200 deaths expected as a direct result. Hepatitis B virus (HBV) hepatitis C virus (HCV), and hepatitis D virus (HDV) all play critical roles in the pathogenesis of hepatocellular carcinoma (HCC), despite the rising prevalence of HCC due to non-infectious causes. Liver cirrhosis and HCC are devastating consequences of HBV and HCV infections, which are widespread worldwide. Associated with a high mortality rate, these infections cause about 1.3 million deaths annually and are the primary cause of HCC globally. In addition to causing insertional mutations due to viral gene integration, epigenetic alterations and inducing chronic immunological dysfunction are all methods by which these viruses turn hepatocytes into cancerous ones. While expanding our knowledge of the illness, identifying these pathways also give possibilities for novel diagnostic and treatment methods. Nuclear factor erythroid 2-related factor 2 (NRF2) activation is gaining popularity as a treatment option for oxidative stress (OS), inflammation, and metabolic abnormalities. Numerous studies have shown that elevated Nrf2 expression is linked to HCC, providing more evidence that Nrf2 is a critical factor in HCC. This aberrant Nrf2 signaling drives cell proliferation, initiates angiogenesis and invasion, and imparts drug resistance. As a result, this master regulator may be a promising treatment target for HCC. In addition, the activation of Nrf2 is a common viral effect that contributes to the pathogenesis, development, and chronicity of virus infection. However, certain viruses suppress Nrf2 activity, which is helpful to the virus in maintaining cellular homeostasis. In this paper, we discussed the influence of Nrf2 deregulation on the viral life cycle and the pathogenesis associated with HBV and HCV. We summed up the mechanisms for the modulation of Nrf2 that are deregulated by these viruses. Moreover, we describe the molecular mechanism by which Nrf2 is modulated in liver cancer, liver cancer stem cells (LCSCs), and liver cancer caused by HBV and HCV. Video Abstract.

Circadian clock1a coordinates neutrophil recruitment via nfe212a/duox-reactive oxygen species pathway in zebrafish

Neutrophil recruitment to inflammatory sites appears to be an evolutionarily conserved strategy to fight against exogenous insults. However, the rhythmic characteristics and underlying mechanisms of neutrophil migration on a 24-h timescale are largely unknown. Using the advantage of in vivo imaging of zebrafish, this study explored how the circadian gene clock1a dynamically regulates the rhythmic recruitment of neutrophils to inflammatory challenges. We generated a clock1a mutant and found that neutrophil migration is significantly increased in caudal fin injury and lipopolysaccharide (LPS) injection. Transcriptome sequencing, chromatin immunoprecipitation (ChIP), and dual-luciferase reporting experiments suggest that the clock1a gene regulates neutrophil migration by coordinating the rhythmic expression of nfe212a and duox genes to control the reactive oxygen species (ROS) level. This study ultimately provides a visual model to expand the understanding of the rhythmic mechanisms of neutrophil recruitment on a circadian timescale in a diurnal organism from the perspective of ROS.

Gentiopicroside ameliorates CCl4-induced liver injury in mice by regulating the PPAR-γ/Nrf2 and NF-κB/IκB signaling pathways

OBJECTIVE

This study explored the mechanisms by which gentiopicroside protects against carbon tetrachloride (CCl4)-induced liver injury.

METHODS

Male mice were randomly assigned to the control; CCl4; bifendate 100 mg/kg; or gentiopicroside 25, 50, or 100 mg/kg groups. Both vehicle and drugs were administered intragastrically for 7 days. Mice were administered CCl4 intraperitoneally 1 hour after the last drug dose. After 24 hours, we collected blood and liver samples for testing.

RESULTS

Gentiopicroside significantly reduced serum alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase activities with corresponding reductions in hepatocyte denaturation and necrosis. Gentiopicroside enhanced superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and glutathione levels and reduced heme oxygenase 1 (HO-1) activity and malondialdehyde levels in the liver, and these effects were attributed to peroxisome proliferator-activated receptor (PPAR)-γ/nuclear factor erythroid 2-related factor 2 (Nrf2) activation. Meanwhile, gentiopicroside significantly downregulated HO-1 and upregulated SOD and GSH-Px at the mRNA level in the liver. Furthermore, gentiopicroside significantly suppressed serum tumor necrosis factor-α and interleukin-1β secretion, which was associated with the inhibition of nuclear factor-kappa B (NF-κB)/inhibitor of NF-κB (IκB).

CONCLUSIONS

Gentiopicroside ameliorated CCl4-induced liver injury in mice via the PPAR-γ/Nrf2 and NF-κB/IκB pathways.

Recent Insights into the Biomarkers, Molecular Targets and Mechanisms of Non-Alcoholic Steatohepatitis-Driven Hepatocarcinogenesis

Non-alcoholic fatty liver disease (NAFLD) or metabolic dysfunction-associated steatotic liver disease (MASLD) and steatohepatitis (NASH) are chronic hepatic conditions leading to hepatocellular carcinoma (HCC) development. According to the recent "multiple-parallel-hits hypothesis", NASH could be caused by abnormal metabolism, accumulation of lipids, mitochondrial dysfunction, and oxidative and endoplasmic reticulum stresses and is found in obese and non-obese patients. Recent translational research studies have discovered new proteins and signaling pathways that are involved not only in the development of NAFLD but also in its progression to NASH, cirrhosis, and HCC. Nevertheless, the mechanisms of HCC developing from precancerous lesions have not yet been fully elucidated. Now, it is of particular importance to start research focusing on the discovery of novel molecular pathways that mediate alterations in glucose and lipid metabolism, which leads to the development of liver steatosis. The role of mTOR signaling in NASH progression to HCC has recently attracted attention. The goals of this review are (1) to highlight recent research on novel genetic and protein contributions to NAFLD/NASH; (2) to investigate how recent scientific findings might outline the process that causes NASH-associated HCC; and (3) to explore the reliable biomarkers/targets of NAFLD/NASH-associated hepatocarcinogenesis.

Liquiritigenin Confers Liver Protection by Enhancing NRF2 Signaling through Both Canonical and Non-canonical Signaling Pathways

Oxidative stress plays a critical role in drug-induced liver injury. In recent years, liquiritigenin (LQ), a natural flavonoid distributed in Glycyrrhizae Radix et Rhizoma (Gan Cao), shows protective effects against oxidative hepatotoxicity. However, the underlying mechanism remains unclear. In this study, we mainly investigated the role of NRF2, a core transcription factor in oxidative stress, in LQ-induced hepatoprotection. Our results indicated that the function of LQ to eliminate reactive oxygen species in liver cells was dependent on NRF2 activation. Both a canonical signaling pathway and a non-canonical signaling pathway are involved in LQ-induced NRF2 activation. LQ induced NRF2 activation in a KEAP1-C151-dependent manner partially. Meanwhile, LQ led to the blockage of autophagic flux and upregulation of p62, which competitively bound with KEAP1 and conferred NRF2 activation in a KEAP1-C151-independent manner. Totally, our study reveals a novel molecular mechanism underlying the hepatoprotection of LQ, providing a new insight into the pathogenesis and therapeutic strategy of oxidative liver injury.

Reduced mitophagy is an early feature of NAFLD and liver-specific PARKIN knockout hastens the onset of steatosis, inflammation and fibrosis

Nonalcoholic fatty liver disease (NAFLD) encompasses a spectrum of pathologies that includes steatosis, steatohepatitis (NASH) and fibrosis and is strongly associated with insulin resistance and type 2 diabetes. Changes in mitochondrial function are implicated in the pathogenesis of NAFLD, particularly in the transition from steatosis to NASH. Mitophagy is a mitochondrial quality control mechanism that allows for the selective removal of damaged mitochondria from the cell via the autophagy pathway. While past work demonstrated a negative association between liver fat content and rates of mitophagy, when changes in mitophagy occur during the pathogenesis of NAFLD and whether such changes contribute to the primary endpoints associated with the disease are currently poorly defined. We therefore undertook the studies described here to establish when alterations in mitophagy occur during the pathogenesis of NAFLD, as well as to determine the effects of genetic inhibition of mitophagy via conditional deletion of a key mitophagy regulator, PARKIN, on the development of steatosis, insulin resistance, inflammation and fibrosis. We find that loss of mitophagy occurs early in the pathogenesis of NAFLD and that loss of PARKIN accelerates the onset of key NAFLD disease features. These observations suggest that loss of mitochondrial quality control in response to nutritional stress may contribute to mitochondrial dysfunction and the pathogenesis of NAFLD.

Anti-Ferroptotic Effects of Nrf2: Beyond the Antioxidant Response

The transcription factor Nrf2 was originally identified as a master regulator of redox homeostasis, as it governs the expression of a battery of genes involved in mitigating oxidative and electrophilic stress. However, the central role of Nrf2 in dictating multiple facets of the cellular stress response has defined the Nrf2 pathway as a general mediator of cell survival. Recent studies have indicated that Nrf2 regulates the expression of genes controlling ferroptosis, an ironand lipid peroxidation-dependent form of cell death. While Nrf2 was initially thought to have anti-ferroptotic function primarily through regulation of the antioxidant response, accumulating evidence has indicated that Nrf2 also exerts anti-ferroptotic effects via regulation of key aspects of iron and lipid metabolism. In this review, we will explore the emerging role of Nrf2 in mediating iron homeostasis and lipid peroxidation, where several Nrf2 target genes have been identified that encode critical proteins involved in these pathways. A better understanding of the mechanistic relationship between Nrf2 and ferroptosis, including how genetic and/or pharmacological manipulation of Nrf2 affect the ferroptotic response, should facilitate the development of new therapies that can be used to treat ferroptosis-associated diseases.

Inhibition of autophagy and MEK promotes ferroptosis in Lkb1-deficient Kras-driven lung tumors

LKB1 and KRAS are the third most frequent co-mutations detected in non-small cell lung cancer (NSCLC) and cause aggressive tumor growth. Unfortunately, treatment with RAS-RAF-MEK-ERK pathway inhibitors has minimal therapeutic efficacy in LKB1-mutant KRAS-driven NSCLC. Autophagy, an intracellular nutrient scavenging pathway, compensates for Lkb1 loss to support Kras-driven lung tumor growth. Here we preclinically evaluate the possibility of autophagy inhibition together with MEK inhibition as a treatment for Kras-driven lung tumors. We found that the combination of the autophagy inhibitor hydroxychloroquine (HCQ) and the MEK inhibitor Trametinib displays synergistic anti-proliferative activity in KrasG12D/+;Lkb1-/- (KL) lung cancer cells, but not in KrasG12D/+;p53-/- (KP) lung cancer cells. In vivo studies using tumor allografts, genetically engineered mouse models (GEMMs) and patient-derived xenografts (PDXs) showed anti-tumor activity of the combination of HCQ and Trametinib on KL but not KP tumors. We further found that the combination treatment significantly reduced mitochondrial membrane potential, basal respiration, and ATP production, while also increasing lipid peroxidation, indicative of ferroptosis, in KL tumor-derived cell lines (TDCLs) and KL tumors compared to treatment with single agents. Moreover, the reduced tumor growth by the combination treatment was rescued by ferroptosis inhibitor. Taken together, we demonstrate that autophagy upregulation in KL tumors causes resistance to Trametinib by inhibiting ferroptosis. Therefore, a combination of autophagy and MEK inhibition could be a novel therapeutic strategy to specifically treat NSCLC bearing co-mutations of LKB1 and KRAS.

Reduced hepatocyte mitophagy is an early feature of NAFLD pathogenesis and hastens the onset of steatosis, inflammation and fibrosis

Nonalcoholic fatty liver disease (NAFLD) encompasses a spectrum of pathologies that includes steatosis, steatohepatitis (NASH) and fibrosis and is strongly associated with insulin resistance and type 2 diabetes. Changes in mitochondrial function are implicated in the pathogenesis of NAFLD, particularly in the transition from steatosis to NASH. Mitophagy is a mitochondrial quality control mechanism that allows for the selective removal of damaged mitochondria from the cell via the autophagy pathway. While past work demonstrated a negative association between liver fat content and rates of mitophagy, when changes in mitophagy occur during the pathogenesis of NAFLD and whether such changes contribute to the primary endpoints associated with the disease are currently poorly defined. We therefore undertook the studies described here to establish when alterations in mitophagy occur during the pathogenesis of NAFLD, as well as to determine the effects of genetic inhibition of mitophagy via conditional deletion of a key mitophagy regulator, PARKIN, on the development of steatosis, insulin resistance, inflammation and fibrosis. We find that loss of mitophagy occurs early in the pathogenesis of NAFLD and that loss of PARKIN hastens the onset but not severity of key NAFLD disease features. These observations suggest that loss of mitochondrial quality control in response to nutritional stress may contribute to mitochondrial dysfunction and the pathogenesis of NAFLD.