Adipocyte GPX4 protects against inflammation, hepatic insulin resistance and metabolic dysregulation

Adipocyte-derived ferroptotic signaling mitigates obesity

Ferroptosis is characterized as an iron-dependent and lipophilic form of cell death. However, it remains unclear what role ferroptosis has in adipose tissue function and activity. Here, we find a lower ferroptotic signature in the adipose tissue of individuals and mice with obesity. We further find that activation of ferroptotic signaling by a non-lethal dose of ferroptosis agonists significantly reduces lipid accumulation in primary adipocytes and high-fat diet (HFD)-fed mice. Notably, adipocyte-specific overexpression of acyl-coenzyme A synthetase long-chain family member 4 (Acsl4) or deletion of ferritin heavy chain (Fth) protects mice from HFD-induced adipose expansion and metabolic disorders via activation of ferroptotic signaling. Mechanistically, we find that 5,15-dihydroxyeicosatetraenoic acid (5,15-DiHETE) activates ferroptotic signaling, resulting in the degradation of hypoxia-inducible factor-1α (HIF1α), thereby derepressing a thermogenic program regulated by the c-Myc-peroxisome proliferator-activated receptor gamma coactivator-1 beta (Pgc1β) pathway. Our findings suggest that activating ferroptosis signaling in adipose tissues might help to prevent and treat obesity and its related metabolic disorders.

Ferroptosis in adipose tissue: A promising pathway for treating obesity?

Using a high-fat-diet (HFD) mouse model and clinical samples, Wang et al.1 in this issue of Cell Metabolism report that ferroptotic signaling is involved in the expansion of adipose tissue and promotes adaptive thermogenesis in beige adipocytes. This finding may represent a promising new avenue for treating obesity.

Double-edged sword effect of GPX4 in skin homeostasis and diseases

Glutathione peroxidase 4 (GPX4) is a crucial antioxidant enzyme that plays a vital role in protecting cells from oxidative damage and lipid peroxidation. In the context of skin diseases, GPX4 serves as a key regulator of oxidative stress and inflammation, both of which are significant features of various skin conditions. By preventing lipid peroxidation and maintaining membrane integrity, GPX4 acts as a safeguard against cell death pathways, particularly ferroptosis, in skin diseases. Dysregulation of GPX4 in conditions such as dermatitis, psoriasis, and skin cancer is linked to heightened oxidative stress, inflammation, and tissue damage. Understanding the role of GPX4 and its intricate interactions in skin disease pathogenesis can aid in more effectively targeting oxidative stress and inflammation, leading to promising therapeutic interventions. This review summarizes the role of GPX4 in maintaining skin homeostasis and its involvement in disease, proposing strategies to target GPX4, including its post-translational modifications. Investigate the precise mechanism through which GPX4 influences the onset of skin diseases, and utilize GPX4 agonists or inhibitors as potential treatments.

Molecular mechanisms of ferroptosis in cardiovascular disease

Ferroptosis is a newly recognized type of regulated cell death that is characterized by the accumulation of iron and lipid peroxides in cells. Studies have shown that ferroptosis plays a significant role in the pathogenesis of various diseases, including cardiovascular diseases. In cardiovascular disease, ferroptosis is associated with ischemia-reperfusion injury, myocardial infarction, heart failure, and atherosclerosis. The molecular mechanisms underlying ferroptosis include the iron-dependent accumulation of lipid peroxidation products, glutathione depletion, and dysregulation of lipid metabolism, among others. This review aims to summarize the current knowledge of the molecular mechanisms of ferroptosis in cardiovascular disease and discuss the potential therapeutic strategies targeting ferroptosis as a treatment for cardiovascular disease.

Iron homeostasis and ferroptosis in human diseases: mechanisms and therapeutic prospects

Iron, an essential mineral in the body, is involved in numerous physiological processes, making the maintenance of iron homeostasis crucial for overall health. Both iron overload and deficiency can cause various disorders and human diseases. Ferroptosis, a form of cell death dependent on iron, is characterized by the extensive peroxidation of lipids. Unlike other kinds of classical unprogrammed cell death, ferroptosis is primarily linked to disruptions in iron metabolism, lipid peroxidation, and antioxidant system imbalance. Ferroptosis is regulated through transcription, translation, and post-translational modifications, which affect cellular sensitivity to ferroptosis. Over the past decade or so, numerous diseases have been linked to ferroptosis as part of their etiology, including cancers, metabolic disorders, autoimmune diseases, central nervous system diseases, cardiovascular diseases, and musculoskeletal diseases. Ferroptosis-related proteins have become attractive targets for many major human diseases that are currently incurable, and some ferroptosis regulators have shown therapeutic effects in clinical trials although further validation of their clinical potential is needed. Therefore, in-depth analysis of ferroptosis and its potential molecular mechanisms in human diseases may offer additional strategies for clinical prevention and treatment. In this review, we discuss the physiological significance of iron homeostasis in the body, the potential contribution of ferroptosis to the etiology and development of human diseases, along with the evidence supporting targeting ferroptosis as a therapeutic approach. Importantly, we evaluate recent potential therapeutic targets and promising interventions, providing guidance for future targeted treatment therapies against human diseases.

Aerobic Exercise Training Protects Against Insulin Resistance, Despite Low-Sodium Diet-Induced Increased Inflammation and Visceral Adiposity

Dietary sodium restriction increases plasma triglycerides (TG) and total cholesterol (TC) concentrations as well as causing insulin resistance and stimulation of the renin-angiotensin-aldosterone system (RAAS) and the sympathetic nervous system. Stimulation of the angiotensin II type-1 receptor (AT1) is associated with insulin resistance, inflammation, and the inhibition of adipogenesis. The current study investigated whether aerobic exercise training (AET) mitigates or inhibits the adverse effects of dietary sodium restriction on adiposity, inflammation, and insulin sensitivity in periepididymal adipose tissue. LDL receptor knockout mice were fed either a normal-sodium (NS; 1.27% NaCl) or a low-sodium (LS; 0.15% NaCl) diet and were either subjected to AET for 90 days or kept sedentary. Body mass, blood pressure (BP), hematocrit, plasma TC, TG, glucose and 24-hour urinary sodium (UNa) concentrations, insulin sensitivity, lipoprotein profile, histopathological analyses, and gene and protein expression were determined. The results were evaluated using two-way ANOVA. Differences were not observed in BP, hematocrit, diet consumption, and TC. The LS diet was found to enhance body mass, insulin resistance, plasma glucose, TG, LDL-C, and VLDL-TG and reduce UNa, HDL-C, and HDL-TG, showing a pro-atherogenic lipid profile. In periepididymal adipose tissue, the LS diet increased tissue mass, TG, TC, AT1 receptor, pro-inflammatory macro-phages contents, and the area of adipocytes; contrarily, the LS diet decreased anti-inflammatory macrophages, protein contents and the transcription of genes related to insulin sensitivity. The AET prevented insulin resistance, but did not protect against dyslipidemia, adipose tissue pro-inflammatory profile, increased tissue mass, AT1 receptor expression, TG, and TC induced by the LS diet.

GSTO2 ameliorates human neuroblastoma cell apoptosis, inflammation, ferroptosis, and oxidative stress by upregulating GPX4 expression in intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a severe hemorrhagic stroke and induces severe secondary neurological injury. However, its pathogenesis remains to be explored. The present work investigates the role of glutathione S-transferase omega 2 (GSTO2) in ICH and the underlying mechanism. Human neuroblastoma cells (SK-N-SH) were stimulated using hemin to mimic ICH-like injury. Protein expression levels of GSTO2 and glutathione peroxidase 4 (GPX4) were detected by western blot analysis assay. Cell viability was assessed by cell counting kit-8 assay. Cell proliferation was investigated by 5-ethynyl-2'-deoxyuridine assay. Cell apoptosis was analyzed by flow cytometry. Interleukin-6 and tumor necrosis factor-α levels were quantified by enzyme-linked immunosorbent assays. Fe2+ colorimetric assay kit was used to detect Fe2+ level. A cellular reactive oxygen species (ROS) assay kit was used to detect ROS levels. Malondialdehyde (MDA) level was assessed using the MDA content assay kit. GSH level was quantified using the GSH assay kit. Co-immunoprecipitation assay was performed to identify the association between GSTO2 and GPX4. Hemin stimulation suppressed SK-N-SH cell proliferation and promoted cell apoptosis, cell inflammation, ferroptosis, and oxidative stress. GSTO2 expression was downregulated in hemin-treated SK-N-SH cells in comparison with the control group. In addition, ectopic GSTO2 expression counteracted hemin-induced inhibitory effect on cell proliferation and promoting effects on cell apoptosis, inflammation, ferroptosis, and oxidative stress. Moreover, GSTO2 was associated with GPX4 in SK-N-SH cells. GPX4 silencing attenuated GSTO2 overexpression-induced effects on hemin-stimulated SK-N-SH cell injury. GSTO2 ameliorated SK-N-SH cell apoptosis, inflammation, ferroptosis, and oxidative stress by upregulating GPX4 expression in ICH, providing a therapeutic strategy for ICH.

Role of hypoxia-inducible-factor-1α (HIF-1α) in ferroptosis of adipose tissue during ketosis

Postpartum cows experience lipolysis in adipose tissue due to negative energy balance (NEB), and accumulation of free fatty acids (FFA) leads to metabolic stress in adipose tissue. Ferroptosis is a type of cell death triggered by excessive buildup of iron-dependent lipid peroxides, which is involved in the occurrence and development of various metabolic diseases in nonruminants. However, it is still unclear whether ferroptosis occurs in the adipose tissue of ketotic cows and the regulatory mechanisms behind ferroptosis. Despite multiple studies demonstrating the significant involvement of hypoxia-inducible-factor-1α (HIF-1α) in regulating cellular dysfunction, its specific function in adipose tissue of ketotic dairy cows remains uncertain, particularly its regulation of oxidative stress and ferroptosis. The study aimed to explore the impact of HIF-1α on oxidative stress and ferroptosis in bovine subcutaneous adipose tissue and isolated adipocytes. The adipose tissue of clinical ketosis cows (n = 15) with a serum BHB concentration of 3.13 mM (interquartile range = 0.14) and healthy cows (n = 15) with a serum BHB concentration of and 0.58 mM (interquartile range = 0.13) was collected. The results showed that the concentrations of lipid peroxidation malondialdehyde (MDA), reactive oxygen species (ROS), Fe2+ and total iron were increased in adipose tissue of cows with ketosis, while the contents of glutathione (GSH) were reduced. Furthermore, the protein levels of HIF-1α, heme oxygenase 1 (HMOX1), catalase (CAT), superoxide dismutase 1 (SOD1), acyl-CoA synthetase 4 (ACSL4), and nuclear factor erythroid-derived 2-like 2 (NFE2L2) exhibited higher abundance in adipose tissue obtained from cows with ketosis, whereas the protein abundance of solute carrier family 7 member 11 (SLC7A11), glutamate cysteine ligase catalytic subunit (GCLC), kelch-like ECH-associated protein 1 (KEAP1), glutamate cysteine ligase regulatory subunit (GCLM) and glutathione peroxidase 4 (GPX4) were lower. To simulate the ferroptosis state of adipose tissue in ketotic cows, primary bovine adipocytes were isolated from the adipose tissue of healthy cows and cultured with erastin to construct ferroptosis model. Adipocytes were cultured with either an adenovirus overexpressing HIF-1α or small interfering RNA targeting HIF-for 48 h, followed by exposure to erastin (1 μM) for 24 h. Treatment with erastin led to higher protein abundance of CAT, SOD1, NFE2L2 and HMOX1, while it inhibited the protein expression levels of GCLC, SLC7A11, GCLM, GPX4 and KEAP1. Furthermore, erastin treatment elevated the levels of ROS, MDA, Fe2+, total iron and reduced the content of GSH. The overexpression of HIF-1α reversed the erastin-induced decreases in the protein abundance of GPX4 and SLC7A11, as well as the levels of MDA, ROS, Fe2+ and total iron, while significantly increasing protein abundance and content of CAT, SOD1, NFE2L2, HMOX1, GCLC, GCLM, GPX4, SLC7A11 and GSH. Conversely, the silencing of HIF-1α further exacerbated the erastin-induced levels of MDA, ROS, Fe2+ and total iron, while inhibiting the upregulation of SOD1, CAT, NFE2L2 and HMOX1. Collectively, these findings suggest that activation of HIF-1α may function as an adaptive mechanism to mitigate ferroptosis and alleviate oxidative stress in adipose tissue.

BCAA-nitrogen flux in brown fat controls metabolic health independent of thermogenesis

Brown adipose tissue (BAT) is best known for thermogenesis. Rodent studies demonstrated that enhanced BAT thermogenesis is tightly associated with increased energy expenditure, reduced body weight, and improved glucose homeostasis. However, human BAT is protective against type 2 diabetes, independent of body weight. The mechanism underlying this dissociation remains unclear. Here, we report that impaired mitochondrial catabolism of branched-chain amino acids (BCAAs) in BAT, by deleting mitochondrial BCAA carriers (MBCs), caused systemic insulin resistance without affecting energy expenditure and body weight. Brown adipocytes catabolized BCAA in the mitochondria as nitrogen donors for the biosynthesis of non-essential amino acids and glutathione. Impaired mitochondrial BCAA-nitrogen flux in BAT resulted in increased oxidative stress, decreased hepatic insulin signaling, and decreased circulating BCAA-derived metabolites. A high-fat diet attenuated BCAA-nitrogen flux and metabolite synthesis in BAT, whereas cold-activated BAT enhanced the synthesis. This work uncovers a metabolite-mediated pathway through which BAT controls metabolic health beyond thermogenesis.

The pathophysiology of MASLD: an immunometabolic perspective

INTRODUCTION

Metabolic-associated liver diseases have emerged pandemically across the globe and are clinically related to metabolic disorders such as obesity and type 2 diabetes. The new nomenclature and definition (i.e. metabolic dysfunction-associated steatotic liver disease - MASLD; metabolic dysfunction-associated steatohepatitis - MASH) reflect the nature of these complex systemic disorders, which are characterized by inflammation, gut dysbiosis and metabolic dysregulation. In this review, we summarize recent advantages in understanding the pathophysiology of MASLD, which we parallel to emerging therapeutic concepts.

AREAS COVERED

We summarize the pathophysiologic concepts of MASLD and its transition to MASH and subsequent advanced sequelae of diseases. Furthermore, we highlight how dietary constituents, microbes and associated metabolites, metabolic perturbations, and immune dysregulation fuel lipotoxicity, hepatic inflammation, liver injury, insulin resistance, and systemic inflammation. Deciphering the intricate pathophysiologic processes that contribute to the development and progression of MASLD is essential to develop targeted therapeutic approaches to combat this escalating burden for health-care systems.

EXPERT OPINION

The rapidly increasing prevalence of metabolic dysfunction-associated steatotic liver disease challenges health-care systems worldwide. Understanding pathophysiologic traits is crucial to improve the prevention and treatment of this disorder and to slow progression into advanced sequelae such as cirrhosis and hepatocellular carcinoma.

Ferroptosis and metabolic syndrome and complications: association, mechanism, and translational applications

Metabolic syndrome is a medical condition characterized by several metabolic disorders in the body. Long-term metabolic disorders raise the risk of cardiovascular disease (CVD) and type 2 diabetes mellitus (T2DM). Therefore, it is essential to actively explore the aetiology of metabolic syndrome (MetS) and its comorbidities to provide effective treatment options. Ferroptosis is a new form of cell death that is characterized by iron overload, lipid peroxide accumulation, and decreased glutathione peroxidase 4(GPX4) activity, and it involves the pathological processes of a variety of diseases. Lipid deposition caused by lipid diseases and iron overload is significant in metabolic syndrome, providing the theoretical conditions for developing ferroptosis. Recent studies have found that the major molecules of ferroptosis are linked to common metabolic syndrome consequences, such as T2DM and atherosclerosis. In this review, we first discussed the mechanics of ferroptosis, the regulatory function of inducers and inhibitors of ferroptosis, and the significance of iron loading in MetS. Next, we summarized the role of ferroptosis in the pathogenesis of MetS, such as obesity, type 2 diabetes, and atherosclerosis. Finally, we discussed relevant ferroptosis-targeted therapies and raised some crucial issues of concern to provide directions for future Mets-related treatments and research.

Primordial Drivers of Diabetes Heart Disease: Comprehensive Insights into Insulin Resistance

Insulin resistance has been regarded as a hallmark of diabetes heart disease (DHD). Numerous studies have shown that insulin resistance can affect blood circulation and myocardium, which indirectly cause cardiac hypertrophy and ventricular remodeling, participating in the pathogenesis of DHD. Meanwhile, hyperinsulinemia, hyperglycemia, and hyperlipidemia associated with insulin resistance can directly impair the metabolism and function of the heart. Targeting insulin resistance is a potential therapeutic strategy for the prevention of DHD. Currently, the role of insulin resistance in the pathogenic development of DHD is still under active research, as the pathological roles involved are complex and not yet fully understood, and the related therapeutic approaches are not well developed. In this review, we describe insulin resistance and add recent advances in the major pathological and physiological changes and underlying mechanisms by which insulin resistance leads to myocardial remodeling and dysfunction in the diabetic heart, including exosomal dysfunction, ferroptosis, and epigenetic factors. In addition, we discuss potential therapeutic approaches to improve insulin resistance and accelerate the development of cardiovascular protection drugs.

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.

Sex-specific effect of P2Y2 purinergic receptor on glucose metabolism during acute inflammation

The sex of an animal impacts glucose sensitivity, but little information is available regarding the mechanisms causing that difference, especially during acute inflammation. We examined sex-specific differences in the role of the P2Y2 receptor (P2Y2R) in glucose flux with and without LPS challenge. Male and female wild-type and P2Y2R knockout mice (P2Y2R-/-) were injected with LPS or saline and glucose tolerance tests (GTT) were performed. P2Y2R, insulin receptor, and GLUT4 transporter gene expression was also evaluated. Female mice had reduced fasting plasma glucose and females had reduced glucose excursion times compared to male mice during GTT. P2Y2R-/- males had significantly decreased glucose flux throughout the GTT as compared to all female mice. Acute inflammation reduced fasting plasma glucose and the GTT area under the curve in both sexes. While both wild-type and P2Y2R-/- male animals displayed reduced fasting glucose in LPS treatment, female mice did not have significant difference in glucose tolerance, suggesting that the effects of P2Y2R are specific to male mice, even under inflammatory conditions. Overall, we conclude that the role for the purinergic receptor, P2Y2R, in regulating glucose metabolism is minimal in females but plays a large role in male mice, particularly in the acute inflammatory state.

Age-related changes in adipose tissue metabolomics and inflammation, cardiolipin metabolism, and ferroptosis markers in female aged rat model

Aging adipose tissue exhibits elevated inflammation and oxidative stress that are major sources of age-related metabolic dysfunction. However, the exact metabolic changes associated with inflammation and oxidative stress are unclear. To address this topic, we assessed variation in metabolic phenotypes of adipose tissue from 18 months adult sedentary (ASED), 26 months old sedentary (OSED), and 8 months young sedentary (YSED). The results of metabolomic analysis showed that ASED and OSED group had higher palmitic acid, elaidic acid, 1-heptadecanol, and α-tocopherol levels than YSED, but lower sarcosine levels. Furthermore, stearic acid was specifically elevated in ASED compared with YSED. Cholesterol was upregulated specifically in the OSED group compared with YSED, whereas linoleic acid was downregulated. In addition, ASED and OSED had more inflammatory cytokines, lower antioxidant capacity, and higher expression of ferroptosis-related genes than YSED. Moreover, mitochondrial dysfunction associated with abnormal cardiolipin synthesis was more pronounced in the OSED group. In conclusion, both ASED and OSED can affect the FA metabolism and increase oxidative stress in adipose tissue, leading to inflammation. In particular, linoleic acid content specifically decreases in OSED, which associated with abnormal cardiolipin synthesis and mitochondrial dysfunction in adipose tissue.

Thermogenic Adipose Redox Mechanisms: Potential Targets for Metabolic Disease Therapies

Metabolic diseases, such as diabetes and non-alcoholic fatty liver disease (NAFLD), have several negative health outcomes on affected humans. Dysregulated energy metabolism is a key component underlying the pathophysiology of these conditions. Adipose tissue is a fundamental regulator of energy homeostasis that utilizes several redox reactions to carry out the metabolism. Brown and beige adipose tissues, in particular, perform highly oxidative reactions during non-shivering thermogenesis to dissipate energy as heat. The appropriate regulation of energy metabolism then requires coordinated antioxidant mechanisms to counterbalance the oxidation reactions. Indeed, non-shivering thermogenesis activation can cause striking changes in concentrations of both oxidants and antioxidants in order to adapt to various oxidative environments. Current therapeutic options for metabolic diseases either translate poorly from rodent models to humans (in part due to the challenges of creating a physiologically relevant rodent model) or tend to have numerous side effects, necessitating novel therapies. As increased brown adipose tissue activity results in enhanced energy expenditure and is associated with beneficial effects on metabolic health, such as decreased obesity, it has gathered great interest as a modulator of metabolic disease. One potential reason for the beneficial health effects may be that although non-shivering thermogenesis is enormously oxidative, it is also associated with decreased oxidant formation after its activation. However, targeting its redox mechanisms specifically to alter metabolic disease remains an underexplored area. Therefore, this review will discuss the role of adipose tissue in energy homeostasis, non-shivering thermogenesis in adults, and redox mechanisms that may serve as novel therapeutic targets of metabolic disease.

Induction mechanism of ferroptosis: A novel therapeutic target in lung disease

Ferroptosis is a newly discovered form of non-apoptotic regulatory cell death driven by iron-dependent lipid peroxidation. Ferroptosis significantly differs from other forms of cell death in terms of biochemistry, genetics, and morphology. Ferroptosis affects many metabolic processes in the body, resulting in disruption of homeostasis, and is related to many types of lung disease. Although current research on ferroptosis remains in the early stage, existing studies have confirmed that ferroptosis is regulated by a variety of genes, mainly involving changes in genes involved in iron homeostasis and lipid peroxidation metabolism. Furthermore, the mechanism of ferroptosis is complex. This review summarizes the confirmed mechanisms that can cause ferroptosis, including activation of glutathione peroxidase 4, synthesis of glutathione, accumulation of reactive oxygen species, and the influence of ferrous ions and p53 proteins. In recent years, the mechanism of ferroptosis in the occurrence and development of many diseases has been studied; the occurrence of ferroptosis will produce an inflammatory storm, and most of the inducing factors and pathological manifestations of lung diseases are also inflammatory reactions. Therefore, we believe that the association between ferroptosis and lung disease deserves further study. This article aims to help readers to better understand the mechanism of ferroptosis, provide new ideas and targets for the treatment of lung diseases, and point out the direction for the development of new targeted drugs for the clinical treatment of lung diseases.

Ferroptosis increases obesity: Crosstalk between adipocytes and the neuroimmune system

Ferroptosis requires not only the accumulation of iron ions, but also changes in many ferroptosis-related regulators, including a decrease in GPX4 and inhibition of SLC7A11 for classical ferroptosis, a deletion of FSP1 or GCH1. Surprisingly, adipose tissue (AT) in the obesity conditions is also accompanied by iron buildup, decreased GSH, and increased ROS. On the neurological side, the pro-inflammatory factor released by AT may have first caused ferroptosis in the vagus nerve by inhibiting of the NRF2-GPX4 pathway, resulting in disorders of the autonomic nervous system. On the immune side, obesity may cause M2 macrophages ferroptosis due to damage to iron-rich ATMs (MFe^hi) and antioxidant ATMs (Mox), and lead to Treg cells ferroptosis through reductions in NRF2, GPX4, and GCH1 levels. At the same time, the reduction in GPX4 may also trigger the ferroptosis of B1 cells. In addition, some studies have also found the role of GPX4 in neutrophil autophagy, which is also worth pondering whether there is a connection with ferroptosis. In conclusion, this review summarizes the associations between neuroimmune regulation associated with obesity and ferroptosis, and on the basis of this, highlights their potential molecular mechanisms, proposing that ferroptosis in one or more cells in a multicellular tissue changes the fate of that tissue.

Inhibition of autophagy with chloroquine dysregulates mitochondrial quality control and energetics in adipocytes

Autophagy is a complex degradation pathway through which damaged or dysfunctional proteins and organelles are removed. Its pharmacological modulators have been extensively used in a wide range of basic research and preclinical studies. However, the effects of these inhibitors on metabolism, in addition to autophagy inhibition, are not fully elucidated. Chloroquine is a clinically relevant compound that inhibits autophagy by preventing the fusion of autophagosomes with lysosomes. In this study, we aimed to examine the effect of chloroquine on mitochondrial quality control and respiratory function by utilizing 3T3-L1 mouse adipocytes treated with chloroquine at various time points. We found that chloroquine could disturb genes related to mitochondrial fission, biogenesis, and mitophagy, leading to mitochondrial DNA damage. Although the inhibition of autophagy by chloroquine resulted in an increased prohibitin expression, respiratory function was downregulated in a time-dependent manner. Moreover, chloroquine treatment induced oxidative stress, apoptosis, and metabolic dysregulation. These data demonstrated that chloroquine significantly affected mitochondrial respiratory function and metabolism, which was consistent with impaired mitochondrial quality associated with autophagy inhibition.

Statin-Induced Geranylgeranyl Pyrophosphate Depletion Promotes Ferroptosis-Related Senescence in Adipose Tissue

Statin treatment is accepted to prevent adverse cardiovascular events. However, atorvastatin, an HMG-CoA reductase inhibitor, has been reported to exhibit distinct effects on senescent phenotypes. Whether atorvastatin can induce adipose tissue senescence and the mechanisms involved are unknown. The effects of atorvastatin-induced senescence were examined in mouse adipose tissue explants. Here, we showed that statin initiated higher levels of mRNA related to cellular senescence markers and senescence-associated secretory phenotype (SASP), as well as increased accumulation of the senescence-associated β-galactosidase (SA-β-gal) stain in adipose tissues. Furthermore, we found that the levels of reactive oxygen species (ROS), malondialdehyde (MDA), and Fe²⁺ were elevated in adipose tissues treated with atorvastatin, accompanied by a decrease in the expression of glutathione (GSH), and glutathione peroxidase 4 (GPX4), indicating an iron-dependent ferroptosis. Atorvastatin-induced was prevented by a selective ferroptosis inhibitor (Fer-1). Moreover, supplementation with geranylgeranyl pyrophosphate (GGPP), a metabolic intermediate, reversed atorvastatin-induced senescence, SASP, and lipid peroxidation in adipose tissue explants. Atorvastatin depleted GGPP production, but not Fer-1. Atorvastatin was able to induce ferroptosis in adipose tissue, which was due to increased ROS and an increase in cellular senescence. Moreover, this effect could be reversed by the supplement of GGPP. Taken together, our results suggest that the induction of ferroptosis contributed to statin-induced cell senescence in adipose tissue.