Autophagy inhibition and ferroptosis activation during atherosclerosis: Hypoxia-inducible factor 1α inhibitor PX-478 alleviates atherosclerosis by inducing autophagy and suppressing ferroptosis in macrophages

Berberine Inhibits Ferroptosis and Stabilizes Atherosclerotic Plaque through NRF2/SLC7A11/GPX4 Pathway

OBJECTIVE

To investigate potential mechanisms of anti-atherosclerosis by berberine (BBR) using ApoE-/- mice.

METHODS

Eight 8-week-old C57BL/6J mice were used as a blank control group (normal), and 56 8-week-old AopE-/- mice were fed a high-fat diet for 12 weeks, according to a completely random method, and were divided into the model group, BBR low-dose group (50 mg/kg, BBRL), BBR medium-dose group (100 mg/kg, BBRM), BBR high-dose group (150 mg/kg, BBRH), BBR+nuclear factor erythroid 2-related factor 2 (NRF2) inhibitor group (100 mg/kg BBR+30 mg/kg ML385, BBRM+ML385), NRF2 inhibitor group (30 mg/kg, ML385), and positive control group (2.5 mg/kg, atorvastatin), 8 in each group. After 4 weeks of intragastric administration, samples were collected and serum, aorta, heart and liver tissues were isolated. Biochemical kits were used to detect serum lipid content and the expression levels of malondialdehyde (MDA) and superoxide dismutase (SOD) in all experimental groups. The pathological changes of atherosclerosis (AS) were observed by aorta gross Oil Red O, aortic sinus hematoxylin-eosin (HE) and Masson staining. Liver lipopathy was observed in mice by HE staining. The morphology of mitochondria in aorta cells was observed under transmission electron microscope. Flow cytometry was used to detect reactive oxygen species (ROS) expression in aorta of mice in each group. The content of ferrous ion Fe2+ in serum of mice was detected by biochemical kit. The mRNA and protein relative expression levels of NRF2, glutathione peroxidase 4 (GPX4) and recombinant solute carrier family 7 member 11 (SLC7A11) were detected by quantitative real time polymerase chain reaction (RT-qPCR) and Western blot, respectively.

RESULTS

BBRM and BBRH groups delayed the progression of AS and reduced the plaque area (P<0.01). The characteristic morphological changes of ferroptosis were rarely observed in BBR-treated AS mice, and the content of Fe2+ in BBR group was significantly lower than that in the model group (P<0.01). BBR decreased ROS and MDA levels in mouse aorta, increased SOD activity (P<0.01), significantly up-regulated NRF2/SLC7A11/GPX4 protein and mRNA expression levels (P<0.01), and inhibited lipid peroxidation. Compared with the model group, the body weight, blood lipid level and aortic plaque area of ML385 group increased (P<0.01); the morphology of mitochondria showed significant ferroptosis characteristics; the serum Fe2+, MDA and ROS levels increased (P<0.05 or P<0.01), and the activity of SOD decreased (P<0.01). Compared with BBRM group, the iron inhibition effect of BBRM+ML385 group was significantly weakened, and the plaque area significantly increased (P<0.01).

CONCLUSION

Through NRF2/SLC7A11/GPX4 pathway, BBR can resist oxidative stress, inhibit ferroptosis, reduce plaque area, stabilize plaque, and exert anti-AS effects.

Emerging role of tumor microenvironmental nutrients and metabolic molecules in ferroptosis: Mechanisms and clinical implications

In recent years, ferroptosis has gradually attracted increasing attention because of its important role in tumors. Ferroptosis resistance is an important cause of tumor metastasis, recurrence and drug resistance. Exploring the initiating factors and specific mechanisms of ferroptosis has become a key strategy to block tumor progression and improve drug sensitivity. As the external space in direct contact with tumor cells, the tumor microenvironment has a great impact on the biological function of tumor cells. The relationships between abnormal environmental characteristics (hypoxia, lactic acid accumulation, etc.) in the microenvironment and ferroptosis of tumor cells has not been fully characterized. This review focuses on the characteristics of the tumor microenvironment and summarizes the mechanisms of ferroptosis under different environmental factors, aiming to provide new insights for subsequent targeted therapy. Moreover, considering the presence of anticancer drugs in the microenvironment, we further summarize the mechanisms of ferroptosis to provide new strategies for the sensitization of tumor cells to drugs.

Interaction between macrophages and ferroptosis: Metabolism, function, and diseases

ABSTRACT

Ferroptosis, an iron-dependent programmed cell death process driven by reactive oxygen species-mediated lipid peroxidation, is regulated by several metabolic processes, including iron metabolism, lipid metabolism, and redox system. Macrophages are a group of innate immune cells that are widely distributed throughout the body, and play pivotal roles in maintaining metabolic balance by its phagocytic and efferocytotic effects. There is a profound association between the biological functions of macrophage and ferroptosis. Therefore, this review aims to elucidate three key aspects of the unique relationship between macrophages and ferroptosis, including macrophage metabolism and their regulation of cellular ferroptosis; ferroptotic stress that modulates functions of macrophage and promotion of inflammation; and the effects of macrophage ferroptosis and its role in diseases. Finally, we also summarize the possible mechanisms of macrophages in regulating the ferroptosis process at the global and local levels, as well as the role of ferroptosis in the macrophage-mediated inflammatory process, to provide new therapeutic insights for a variety of diseases.

The complex interplay between ferroptosis and atherosclerosis

Atherosclerosis, characterized by the accumulation of plaque within the arterial walls, is an intricate cardiovascular disease that often results in severe health issues. Recent studies have emphasized the importance of ferroptosis, a controlled type of cell death dependent on iron, as a critical factor in this disease state. Ferroptosis, distinguished by its reliance on iron and the accumulation of lipid hydroperoxides, offers a unique insight into the pathology of atherosclerotic lesions. This summary encapsulates the current knowledge of the intricate role ferroptosis plays in the onset and progression of atherosclerosis. It explores the molecular processes through which lipid peroxidation and iron metabolism contribute to the development of atheromatous plaques and evaluates the possibility of utilizing ferroptosis as a novel treatment approach for atherosclerosis. By illuminating the intricate relationship between ferroptosis-related processes and atherosclerosis, this review paves the way for future clinical applications and personalized medicine approaches aimed at alleviating the effects of atherosclerosis.

Bioactive polysaccharides mediate ferroptosis to modulate tumor immunotherapy

Polysaccharides from diverse origins exhibit notable bioactivities, particularly their capacity to exert antitumor and immune-enhancing effects. Concurrently, ferroptosis emerges as a distinctive form of regulated cell death characterized by iron-dependent lipid peroxidation, potentially influencing the demise of specific tumor cells and organismal homeostasis. Recent scholarly attention has increasingly focused on utilizing polysaccharides to modulate tumor cell ferroptosis and manipulate cellular immune responses. This article provides an in-depth analysis of contemporary research concerning using polysaccharides to augment antitumor immunity and combat malignancies. Central to our discourse is examining the pivotal role of polysaccharides in mediating ferroptosis, bolstering immune surveillance, and elucidating the interplay between polysaccharides and antitumor immunity. Furthermore, a comprehensive synthesis of the multifaceted roles of polysaccharides in antitumor and immunomodulatory contexts is provided. Recent advances in understanding how polysaccharides enhance immune function by inducing ferroptosis cell death are explained. Lastly, unresolved inquiries are outlined, and potential avenues for future research are proposed, focusing on the translational applications of polysaccharides in antitumor immunotherapy.

A novel mechanism of ferroptosis inhibition-enhanced atherosclerotic plaque stability: YAP1 suppresses vascular smooth muscle cell ferroptosis through GLS1

Atherosclerosis is a leading cause of cardiovascular diseases (CVDs), often resulting in major adverse cardiovascular events (MACEs), such as myocardial infarction and stroke due to the rupture or erosion of vulnerable plaques. Ferroptosis, an iron-dependent form of cell death, has been implicated in the development of atherosclerosis. Despite its involvement in CVDs, the specific role of ferroptosis in atherosclerotic plaque stability remains unclear. In this study, we confirmed the presence of ferroptosis in unstable atherosclerotic plaques and demonstrated that the ferroptosis inhibitor ferrostatin-1 (Fer-1) stabilizes atherosclerotic plaques in apolipoprotein E knockout (Apoe-/-) mice. Using bioinformatic analysis combining RNA sequencing (RNA-seq) with single-cell RNA sequencing (scRNA-seq), we identified Yes-associated protein 1 (YAP1) as a potential key regulator of ferroptosis in vascular smooth muscle cells (VSMCs) of unstable plaques. In vitro, we found that YAP1 protects against oxidized low-density lipoprotein (oxLDL)-induced ferroptosis in VSMCs. Mechanistically, YAP1 exerts its anti-ferroptosis effects by regulating the expression of glutaminase 1 (GLS1) to promote the synthesis of glutamate (Glu) and glutathione (GSH). These findings establish a novel mechanism where the inhibition of ferroptosis promotes the stabilization of atherosclerotic plaques through the YAP1/GLS1 axis, attenuating VSMC ferroptosis. Thus, targeting the YAP1/GLS1 axis to suppress VSMC ferroptosis may represent a novel strategy for preventing and treating unstable atherosclerotic plaques.

Mastoparan M promotes functional recovery in stroke mice by activating autophagy and inhibiting ferroptosis

Neuronal ferroptosis and autophagy are crucial in the pathogenesis of cerebral ischemia-reperfusion injury (CIRI). Mastoparan M (Mast-M), extracted from the crude venom of Vespa magnifica (Smith), comprises 14 amino acid residues. Previous studies suggested that Mast-M reduces neuronal damage following global CIRI, but its protective mechanisms remain unclear. The present study examined the effect of Mast-M on middle cerebral artery occlusion/reperfusion (MCAO/R) induced neurological deficits using Grip, Rotarod, Longa test, and TTC staining, followed by treating the mice for three days with Mast-M (20, 40, and 80 μg/kg, subcutaneously). The results demonstrate that Mast-M promotes functional recovery in mice post-ischemic stroke, evidenced by improved neurological impairment, reduced infarct volume and neuronal damage. Meanwhile, the level of iron (Fe2+) and malonyldialdehyde was decreased in the ischemic hemisphere of MCAO/R mice at 24 hours or 48 hours by Mast-M (80 μg/kg) treatment, while the expression of NRF2, x-CT, GPX4, and LC3B protein was increased. Furthermore, these findings were validated in three models-oxygen-glucose deprivation/ reoxygenation, H2O2-induced peroxidation, and erastin-induced ferroptosis-in hippocampal neuron HT22 cells or primary neurons. These data suggested that Mast-M activates autophagy as well as inhibits ferroptosis. Finally, autophagy inhibitors were introduced to determine the relationship between the autophagy and ferroptosis, indicating that Mast-M alleviates ferroptosis by activating autophagy. Taken together, this study described that Mast-M alleviates cerebral infarction, neurologic impairment, and neuronal damage by activating autophagy and inhibiting ferroptosis, presenting a potential therapeutic approach for CIRI.

The dance of macrophage death: the interplay between the inevitable and the microenvironment

Macrophages are highly plastic cells ubiquitous in various tissues, where they perform diverse functions. They participate in the response to pathogen invasion and inflammation resolution following the immune response, as well as the maintenance of homeostasis and proper tissue functions. Macrophages are generally considered long-lived cells with relatively strong resistance to numerous cytotoxic factors. On the other hand, their death seems to be one of the principal mechanisms by which macrophages perform their physiological functions or can contribute to the development of certain diseases. In this review, we scrutinize three distinct pro-inflammatory programmed cell death pathways - pyroptosis, necroptosis, and ferroptosis - occurring in macrophages under specific circumstances, and explain how these cells appear to undergo dynamic yet not always final changes before ultimately dying. We achieve that by examining the interconnectivity of these cell death types, which in macrophages seem to create a coordinated and flexible system responding to the microenvironment. Finally, we discuss the complexity and consequences of pyroptotic, necroptotic, and ferroptotic pathway induction in macrophages under two pathological conditions - atherosclerosis and cancer. We summarize damage-associated molecular patterns (DAMPs) along with other microenvironmental factors, macrophage polarization states, associated mechanisms as well as general outcomes, as such a comprehensive look at these correlations may point out the proper methodologies and potential therapeutic approaches.

The association between ferroptosis and autophagy in cardiovascular diseases

Autophagy is a process in which cells degrade intracellular substances and play a variety of roles in cells, such as maintaining intracellular homeostasis, preventing cell overgrowth, and removing pathogens. It is highly conserved during the evolution of eukaryotic cells. So far, the study of autophagy is still a hot topic in the field of cytology. Ferroptosis is an iron-dependent form of cell death, accompanied by the accumulation of reactive oxygen species and lipid peroxides. With the deepening of research, it has been found that ferroptosis, like autophagy, is involved in the occurrence and development of cardiovascular diseases. The relationship between autophagy and ferroptosis is complex, and the association between the two in cardiovascular disease remains to be clarified. This article reviews the mechanism of autophagy and ferroptosis and their correlation, and discusses the relationship between them in cardiovascular diseases, which is expected to provide new and important treatment strategies for cardiovascular diseases.

TMT quantitative proteomics analysis reveals molecular mechanism of ferroptosis during beef refrigeration

Ferroptosis is a recently identified cell death process in refrigerated beef, and its mediated protein oxidation and cell death may reduce muscle quality, but the mechanism of ferroptosis is unclear. In the study, free iron accumulation reached 19.670 ± 0.482 μg/g after 6 days refrigeration, the levels of apoptosis, ROS, and lipid peroxidation increased significantly (P < 0.05), and muscle tissue cells exhibited typical ferroptosis characteristics. A total of 377 differentially expressed proteins (DEPs) were identified by TMT quantitative proteomics. 15 DEPs, including transferrin, ferritin, glutathione peroxidase (GPX) 4, and heme oxygenase 1, were involved in lipid peroxidation, Fe2+ and Fe3+ conversion, iron ion accumulation, and mitochondrial oxidative stress to induce ferroptosis. In addition, signalling pathways, such as chemical carcinogenesis-ROS, glutathione metabolism, HIF-1, and PPAR may promote ferroptosis by affecting free iron overload and GPX4 inactivation.

The mechanisms of ferroptosis and its role in atherosclerosis

Ferroptosis is a newly identified form of non-apoptotic programmed cell death, characterized by the iron-dependent accumulation of lethal lipid reactive oxygen species (ROS) and peroxidation of membrane polyunsaturated fatty acid phospholipids (PUFA-PLs). Ferroptosis is unique among other cell death modalities in many aspects. It is initiated by excessive oxidative damage due to iron overload and lipid peroxidation and compromised antioxidant defense systems, including the system Xc-/ glutathione (GSH)/glutathione peroxidase 4 (GPX4) pathway and the GPX4-independent pathways. In the past ten years, ferroptosis was reported to play a critical role in the pathogenesis of various cardiovascular diseases, e.g., atherosclerosis (AS), arrhythmia, heart failure, diabetic cardiomyopathy, and myocardial ischemia-reperfusion injury. Studies have identified dysfunctional iron metabolism and abnormal expression profiles of ferroptosis-related factors, including iron, GSH, GPX4, ferroportin (FPN), and SLC7A11 (xCT), as critical indicators for atherogenesis. Moreover, ferroptosis in plaque cells, i.e., vascular endothelial cell (VEC), macrophage, and vascular smooth muscle cell (VSMC), positively correlate with atherosclerotic plaque development. Many macromolecules, drugs, Chinese herbs, and food extracts can inhibit the atherogenic process by suppressing the ferroptosis of plaque cells. In contrast, some ferroptosis inducers have significant pro-atherogenic effects. However, the mechanisms through which ferroptosis affects the progression of AS still need to be well-known. This review summarizes the molecular mechanisms of ferroptosis and their emerging role in AS, aimed at providing novel, promising druggable targets for anti-AS therapy.

Visualization of the Ferroptosis in Atherosclerotic Plaques with Nanoprobe Engineered by Macrophage Cell Membranes

Atherosclerosis (AS) is the root cause of cardiovascular diseases. Ferroptosis is characterized by highly iron-dependent lipid peroxidation and has been reported to play an important role in the pathogenesis of AS. Visualization of the ferroptosis process in atherosclerotic plaques is of great importance for diagnosing and treating AS. In this work, the rationally designed fluorescent probe FAS1 exhibited excellent advantages including large Stokes shift, sensitivity to environmental viscosity, good photostability, and improved water solubility. It also could co-locate with commercial lipid droplets (LDs) probes (BODIPY 493/503) well in RAW264.7 cells treated by the ferroptosis inducer. After self-assembly into nanoparticles and then encapsulation with macrophage membranes, the engineered FAS1@MM NPs could successfully target the atherosclerotic plaques in Western diet-induced apolipoprotein E knockout (ApoE-/-) mice and reveal the association of ferroptosis with AS through fluorescence imaging in vivo. This study may provide additional insights into the roles of ferroptosis in the diagnosis and treatment of AS.

Iron and atherosclerosis: Lessons learned from rabbits relevant to human disease

The role of iron in promoting atherosclerosis, and hence the cardiovascular, neurodegenerative and other diseases that result from atherosclerosis, has been fiercely controversial. Many studies have been carried out on various rodent models of atherosclerosis, especially on apoE-knockout (apoE-/-) mice, which develop atherosclerosis more readily than normal mice. These apoE-/- mouse studies generally support a role for iron in atherosclerosis development, although there are conflicting results. The purpose of the current article is to describe studies on another animal model that is not genetically manipulated; New Zealand White (NZW) rabbits fed a high-cholesterol diet. This may be a better model than the apoE-/- mice for human atherosclerosis, although it has been given much less attention. Studies on NZW rabbits support the view that iron promotes atherosclerosis, although some uncertainties remain, which need to be resolved by further experimentation.

Lipid-laden foam cells in the pathology of atherosclerosis: shedding light on new therapeutic targets

INTRODUCTION

Lipid-laden foam cells within atherosclerotic plaques are key players in all phases of lesion development including its progression, necrotic core formation, fibrous cap thinning, and eventually plaque rupture. Manipulating foam cell biology is thus an attractive therapeutic strategy at early, middle, and even late stages of atherosclerosis. Traditional therapies have focused on prevention, especially lowering plasma lipid levels. Despite these interventions, atherosclerosis remains a major cause of cardiovascular disease, responsible for the largest numbers of death worldwide.

AREAS COVERED

Foam cells within atherosclerotic plaques are comprised of macrophages, vascular smooth muscle cells, and other cell types which are exposed to high concentrations of lipoproteins accumulating within the subendothelial intimal layer. Macrophage-derived foam cells are particularly well studied and have provided important insights into lipid metabolism and atherogenesis. The contributions of foam cell-based processes are discussed with an emphasis on areas of therapeutic potential and directions for drug development.

EXERT OPINION

As key players in atherosclerosis, foam cells are attractive targets for developing more specific, targeted therapies aimed at resolving atherosclerotic plaques. Recent advances in our understanding of lipid handling within these cells provide insights into how they might be manipulated and clinically translated to better treat atherosclerosis.

Hypoxia inducible factor-1α is an important regulator of macrophage biology

Hypoxia-inducible factor-1 (HIF-1), a heterodimeric transcription factor composed of the α and β subunits, regulates cellular adaptive responses to hypoxia. Macrophages, which are derived from monocytes, function as antigen-presenting cells that activate various immune responses. HIF-1α regulates the immune response, viability, migration, phenotypic plasticity, and metabolism of macrophages. Specifically, macrophage-derived HIF-1α can prevent excessive pro-inflammatory responses by attenuating the transcriptional activity of nuclear factor-kappa B in vivo and in vitro. HIF-1α modulates macrophage migration by inducing the release of various chemokines and providing necessary energy. HIF-1α promotes macrophage M1 polarization by targeting glucose metabolism. Additionally, HIF-1α induces the upregulation of glycolysis-related enzymes and intermediates of the tricarboxylic acid cycle and pentose phosphate pathway. HIF-1α promotes macrophage apoptosis, necroptosis and reduces autophagy. The current review highlights the mechanisms associated with the regulation of HIF-1α stabilization in macrophages as well as the role of HIF-1α in modulating the physiological functions of macrophages.