Induction of ferroptosis promotes vascular smooth muscle cell phenotypic switching and aggravates neointimal hyperplasia in mice

Neutrophil extracellular trap-induced ferroptosis promotes abdominal aortic aneurysm formation via SLC25A11-mediated depletion of mitochondrial glutathione

BACKGROUND

Neutrophil extracellular traps (NETs) induce oxidative stress, which may initiate ferroptosis, an iron-dependent programmed cell death, during abdominal aortic aneurysm (AAA) formation. Mitochondria regulate the progression of ferroptosis, which is characterized by the depletion of mitochondrial glutathione (mitoGSH) levels. However, the mechanisms are poorly understood. This study examined the role of mitoGSH in regulating NET-induced ferroptosis of smooth muscle cells (SMCs) during AAA formation.

METHODS

Concentrations of NET markers were tested in plasma samples. Western blotting and immunofluorescent staining were performed to detect the expression and localization of NET and ferroptosis markers in tissue samples. The role of NETs and SMC ferroptosis during AAA formation was investigated using peptidyl arginine deiminase 4 gene (Padi4) knockout or treatment with a PAD4 inhibitor, ferroptosis inhibitor or activator in an angiotensin II-induced AAA mouse model. The regulatory effect of SLC25A11, a mitochondrial glutathione transporter, on mitoGSH and NET-induced ferroptosis of SMCs was investigated using in vitro and in vivo experiments. Transmission electron microscopy was used to detect mitochondrial damage. Blue native polyacrylamide gel electrophoresis was used to analyze the dimeric and monomeric forms of the protein.

RESULTS

Significantly elevated levels of NETosis and ferroptosis markers in aortic tissue samples were observed during AAA formation. Specifically, NETs promoted AAA formation by inducing ferroptosis of SMCs. Subsequently, SLC25A11 was identified as a potential biomarker for evaluating the clinical prognosis of patients with AAA. Furthermore, NETs decreased the stability and dimerization of SLC25A11, leading to the depletion of mitoGSH. This depletion induced the ferroptosis of SMCs and promoted AAA formation.

CONCLUSION

During AAA formation, NETs regulate the stability of the mitochondrial carrier protein SLC25A11, leading to the depletion of mitoGSH and subsequent activation of NET-induced ferroptosis of SMCs. Preventing mitoGSH depletion and ferroptosis in SMCs is a potential strategy for treating AAA.

LncRNA MIR210HG promotes phenotype switching of pulmonary arterial smooth muscle cells through autophagy-dependent ferroptosis pathway

Hypoxic pulmonary hypertension (HPH) is a pathophysiological syndrome in which pulmonary vascular pressure increases under hypoxic stimulation and there is an urgent need to develop emerging therapies for the treatment of HPH. LncRNA MIR210HG is a long non-coding RNA closely related to hypoxia and has been widely reported in a variety of tumor diseases. But its mechanism in hypoxic pulmonary hypertension is not clear. In this study, we identified for the first time the potential effect of MIR210HG on disease progression in HPH. Furthermore, we investigated the underlying mechanism through which elevated levels of MIR210HG promotes the transition from a contractile phenotype to a synthetic phenotype in PASMCs under hypoxia via activation of autophagy-dependent ferroptosis pathway. While overexpression of HIF-2α in PASMCs under hypoxia significantly reversed the phenotypic changes induced by MIR210HG knockdown. We further investigated the potential positive regulatory relationship between STAT3 and the transcription of MIR210HG in PASMCs under hypoxic conditions. In addition, we established both in vivo and in vitro models of HPH to validate the differential expression of specific markers associated with hypoxia. Our findings suggest a potential mechanism of LncRNA MIR210HG in the progression of HPH and offer potential targets for disease intervention and treatment.

Ganglioside GM3 Protects Against Abdominal Aortic Aneurysm by Suppressing Ferroptosis

BACKGROUND

Abdominal aortic aneurysm (AAA) is a potentially life-threatening vascular condition, but approved medical therapies to prevent AAA progression and rupture are currently lacking. Sphingolipid metabolism disorders are associated with the occurrence and development of AAA. It has been discovered that ganglioside GM3, a sialic acid-containing type of glycosphingolipid, plays a protective role in atherosclerosis, which is an important risk factor for AAA; however, the potential contribution of GM3 to AAA development has not been investigated.

METHODS

We performed a metabolomics study to evaluated GM3 level in plasma of human patients with AAA. We profiled GM3 synthase (ST3GAL5) expression in the mouse model of aneurysm and human AAA tissues through Western blotting and immunofluorescence staining. RNA sequencing, affinity purification and mass spectrometry, proteomic analysis, surface plasmon resonance analysis, and functional studies were used to dissect the molecular mechanism of GM3-regulating ferroptosis. We conditionally deleted and overexpressed St3gal5 in smooth muscle cells (SMCs) in vivo to investigate its role in AAA.

RESULTS

We found significantly reduced plasma levels of GM3 in human patients with AAA. GM3 content and ST3GAL5 expression were decreased in abdominal aortic vascular SMCs in patients with AAA and an AAA mouse model. RNA sequencing analysis showed that ST3GAL5 silencing in human aortic SMCs induced ferroptosis. We showed that GM3 interacted directly with the extracellular domain of TFR1 (transferrin receptor 1), a cell membrane protein critical for cellular iron uptake, and disrupted its interaction with holo-transferrin. SMC-specific St3gal5 knockout exacerbated iron accumulation at lesion sites and significantly promoted AAA development in mice, whereas GM3 supplementation suppressed lipid peroxidation, reduced iron deposition in aortic vascular SMCs, and markedly decreased AAA incidence.

CONCLUSIONS

Together, these results suggest that GM3 dysregulation promotes ferroptosis of vascular SMCs in AAA. Furthermore, GM3 may constitute a new therapeutic target for AAA.

S-propargyl-cysteine promotes the stability of atherosclerotic plaque via maintaining vascular muscle contractile phenotype

Introduction: Plaque rupture in atherosclerosis contributes to various acute cardiovascular events. As a new sulfide-containing donor, S-propargyl-cysteine (SPRC) has been reported to play a beneficial role in cardioprotection, potentially through its anti-inflammatory, anti-oxidative and anti-atherogenic activities. Our previous study observed an increase in eNOS phosphorylation in endothelial cells. However, it remains unclear whether SPRC influences vascular smooth muscle cells (VSMCs) within the plaque and if this effect contributes to plaque stabilization. Methods: An atherosclerotic unstable plaque mouse model was established by subjecting ApoE-/- mice to tandem stenosis of the right carotid artery along with a Western diet. Daily SPRC administration was conducted for 13 weeks. Plaque morphology and stability were assessed using MRI scanning and histopathological staining. In our in vitro studies, we stimulated human artery vascular smooth muscle cells (HAVSMCs) with platelet-derived growth factor-BB (PDGF-BB), both with and without 100 μM SPRC treatment. Cell phenotype was assessed using both Western blot and Real-time PCR. Cell proliferation was assessed using the BrdU cell proliferation kit and immunofluorescence of Ki-67, while cell migration was measured using scratch wound healing and transwell assay. MiR-143-3p overexpression and knockdown experiments were used to investigate whether it mediates the effect of SPRC on VSMC phenotype. Results and Discussion: SPRC treatment reduced plasma lipid levels, increased collagen content and decreased cell apoptosis in atherosclerotic plaques, indicating improved plaque stability. Both in vivo and in vitro studies elucidated the role of SPRC in preserving the contractile phenotype of VSMCs through up-regulation of miR-143-3p expression. Furthermore, SPRC suppressed the pro-proliferation and pro-migration effects of PDGF-BB on HAVSMCs. Overall, these findings suggest that the inhibitory effect of SPRC on phenotype switch from contractile to synthetic VSMCs may contribute to its beneficial role in enhancing plaque stability.

Pharmacological inhibition of MALT1 (mucosa-associated lymphoid tissue lymphoma translocation protein 1) induces ferroptosis in vascular smooth muscle cells

MALT1 (mucosa-associated lymphoid tissue lymphoma translocation protein 1) is a human paracaspase protein with proteolytic activity via its caspase-like domain. The pharmacological inhibition of MALT1 by MI-2, a specific chemical inhibitor, diminishes the response of endothelial cells to inflammatory stimuli. However, it is largely unknown how MALT1 regulates the functions of vascular smooth muscle cells (SMCs). This study aims to investigate the impact of MALT1 inhibition by MI-2 on the functions of vascular SMCs, both in vitro and in vivo. MI-2 treatment led to concentration- and time-dependent cell death of cultured aortic SMCs, which was rescued by the iron chelator deferoxamine (DFO) or ferrostatin-1 (Fer-1), a specific inhibitor of ferroptosis, but not by inhibitors of apoptosis (Z-VAD-fmk), pyroptosis (Z-YVAD-fmk), or necrosis (Necrostatin-1, Nec-1). MI-2 treatment downregulated the expression of glutathione peroxidase 4 (GPX4) and ferritin heavy polypeptide 1 (FTH1), which was prevented by pre-treatment with DFO or Fer-1. MI-2 treatment also activated autophagy, which was inhibited by Atg7 deficiency or bafilomycin A1 preventing MI-2-induced ferroptosis. MI-2 treatment reduced the cleavage of cylindromatosis (CYLD), a specific substrate of MALT1. Notably, MI-2 treatment led to a rapid loss of contractility in mouse aortas, which was prevented by co-incubation with Fer-1. Moreover, local application of MI-2 significantly reduced carotid neointima lesions and atherosclerosis in C57BL/6J mice and apolipoprotein-E knockout (ApoE-/-) mice, respectively, which were both ameliorated by co-treatment with Fer-1. In conclusion, the present study demonstrated that MALT1 inhibition induces ferroptosis of vascular SMCs, likely contributing to its amelioration of proliferative vascular diseases.

Ferroptosis in the post-transplantation inflammatory response

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

Histone acetyltransferase P300 deficiency promotes ferroptosis of vascular smooth muscle cells by activating the HIF-1α/HMOX1 axis

BACKGROUND

E1A-associated 300-kDa protein (P300), an endogenous histone acetyltransferase, contributes to modifications of the chromatin landscape of genes involved in multiple cardiovascular diseases. Ferroptosis of vascular smooth muscle cells (VSMCs) is a novel pathological mechanism of aortic dissection. However, whether P300 regulates VSMC ferroptosis remains unknown.

METHODS

Cystine deprivation (CD) and imidazole ketone erastin (IKE) were used to induce VSMC ferroptosis. Two different knockdown plasmids targeting P300 and A-485 (a specific inhibitor of P300) were used to investigate the function of P300 in the ferroptosis of human aortic smooth muscle cells (HASMCs). Cell counting kit-8, lactate dehydrogenase and flow cytometry with propidium iodide staining were performed to assess the cell viability and death under the treatment of CD and IKE. BODIPY-C11 assay, immunofluorescence staining of 4-hydroxynonenal and malondialdehyde assay were conducted to detect the level of lipid peroxidation. Furthermore, co-immunoprecipitation was utilized to explore the interaction between P300 and HIF-1α, HIF-1α and P53.

RESULTS

Compared with normal control, the protein level of P300 was significantly decreased in HASMCs treated with CD and IKE, which was largely nullified by the ferroptosis inhibitor ferrostatin-1 but not by the autophagy inhibitor or apoptosis inhibitor. Knockdown of P300 by short-hairpin RNA or inhibition of P300 activity by A-485 promoted CD- and IKE-induced HASMC ferroptosis, as evidenced by a reduction in cell viability and aggravation of lipid peroxidation of HASMCs. Furthermore, we found that hypoxia-inducible factor-1α (HIF-1α)/heme oxygenase 1 (HMOX1) pathway was responsible for the impacts of P300 on ferroptosis of HASMCs. The results of co-immunoprecipitation demonstrated that P300 and P53 competitively bound HIF-1α to regulate the expression of HMOX1. Under normal conditions, P300 interacted with HIF-1α to inhibit HMOX1 expression, while reduced expression of P300 induced by ferroptosis inducers would favor HIF-1α binding to P53 to trigger HMOX1 overexpression. Furthermore, the aggravated effects of P300 knockdown on HASMC ferroptosis were largely nullified by HIF-1α knockdown or the HIF-1α inhibitor BAY87-2243.

CONCLUSION

Thus, our results revealed that P300 deficiency or inactivation facilitated CD- and IKE-induced VSMC ferroptosis by activating the HIF-1α/HMOX1 axis, which may contribute to the development of diseases related to VSMC ferroptosis.

Mesenchymal stem cell-derived extracellular vesicles protect against abdominal aortic aneurysm formation by inhibiting NET-induced ferroptosis

Neutrophil extracellular traps (NETs) play an important role in abdominal aortic aneurysm (AAA) formation; however, the underlying molecular mechanisms remain unclear. Mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) may exert therapeutic effects on AAA through their immunomodulatory and regenerative abilities. This study aimed to examine the role and mechanism of MSC-EVs in regulating the development of NET-mediated AAA. Excessive release of NETs was observed in patients with AAA, and the levels of NET components were associated with the clinical outcomes of the patients. Datasets from the Gene Expression Omnibus database were analyzed and revealed that the PI3K/AKT pathway and ferroptosis were strongly associated with NETosis during AAA formation. Further experiments verified that NETs promoted AAA formation by inducing ferroptosis in smooth muscle cells (SMCs) by inhibiting the PI3K/AKT pathway. The PI3K agonist 740 Y-P, the ferroptosis inhibitor ferrostatin-1, and Padi4 deficiency significantly prevented AAA formation. MSC-EVs attenuated AAA formation by reducing NET release in an angiotensin II-induced AAA mouse model. In vitro experiments revealed that MSC-EVs reduced the release of NETs by shifting NETosis to apoptosis. Our study indicates an important role for NET-induced SMC ferroptosis in AAA formation and provides several potential targets for AAA treatment.