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Invasion and adhesion of neutrophils into tissues and their concomitant secretion play an important role in the development of vascular pathologies, including abdominal aortic aneurysm (AAA). Chronic administration of angiotensin II is used to initiate AAA formation in mice. The role of aldosterone in this process is being studied. We conducted for the first time a complex comparative study of the effects of angiotensin II and aldosterone on the adhesion of human neutrophils to fibronectin and the concomitant secretion of proteins, free amino acids as well as reactive oxygen (ROS) and nitrogen (NO) species. Neither angiotensin II nor aldosterone affected the attachment of neutrophils to fibronectin and the concomitant production of ROS. We showed for the first time that aldosterone stimulated the release of amino acid hydroxylysine, a product of lysyl hydroxylase, the activity of which is positively correlated with cell invasiveness. Aldosterone also initiates the secretion of matrix metalloproteinase 9 (MMP-9) and cathepsin G, which may reorganize the extracellular matrix and stimulate the recruitment and adhesion of neutrophils to the aortic walls. Angiotensin II did not affect protein secretion. It may contribute to neutrophil-induced vascular injury by inhibiting the production of NO or by increasing the secretion of isoleucine. Our results suggest that it is aldosterone-induced neutrophil secretion that may play a significant role in neutrophil-induced vascular wall destruction in angiotensin II-induced AAA or other vascular complications., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Aims: Abdominal aortic aneurysm (AAA) is a common, serious vascular disease with no effective pharmacological treatment. The nucleoside adenosine plays an important role in modulating vascular homeostasis, which prompted us to determine whether adenosine kinase (ADK), an adenosine metabolizing enzyme, modulates AAA formation via control of the intracellular adenosine level, and to investigate the underlying mechanisms., Methods and Results: We used a combination of genetic and pharmacological approaches in murine models of AAA induced by calcium chloride (CaCl2) application or angiotensin II (Ang II) infusion to study the role of ADK in the development of AAA. In vitro functional assays were performed by knocking down ADK with adenovirus-short hairpin RNA in human vascular smooth muscle cells (VSMCs), and the molecular mechanisms underlying ADK function were investigated using RNA-sequencing, isotope tracing, and chromatin immunoprecipitation quantitative polymerase chain reaction (ChIP-qPCR). The heterozygous deficiency of ADK protected mice from CaCl2- and Ang II-induced AAA formation. Moreover, specific knockout of ADK in VSMCs prevented Ang II-induced AAA formation, as evidenced by reduced aortic extracellular elastin fragmentation, neovascularization, and aortic inflammation. Mechanistically, ADK knockdown in VSMCs markedly suppressed the expression of inflammatory genes associated with AAA formation, and these effects were independent of adenosine receptors. The metabolic flux and ChIP-qPCR results showed that ADK knockdown in VSMCs decreased S-adenosylmethionine (SAM)-dependent transmethylation, thereby reducing H3K4me3 binding to the promoter regions of the genes that are associated with inflammation, angiogenesis, and extracellular elastin fragmentation. Furthermore, the ADK inhibitor ABT702 protected mice from CaCl2-induced aortic inflammation, extracellular elastin fragmentation, and AAA formation., Conclusion: Our findings reveal a novel role for ADK inhibition in attenuating AAA via epigenetic modulation of key inflammatory genes linked to AAA pathogenesis., Competing Interests: Conflict of interest: none declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Obstructive sleep apnea (OSA), characterized by episodes of intermittent hypoxia (IH), is highly prevalent in patients with abdominal aortic aneurysm (AAA). However, whether IH serves as an independent risk factor for AAA development remains to be investigated. Here, we determined the effects of chronic (6 mo) IH on angiotensin (Ang II)-induced AAA development in C57BL/6J male mice and investigated the underlying mechanisms of IH in cultured vascular smooth muscle cells (SMCs). IH increased the susceptibility of mice to develop AAA in response to Ang II infusion by facilitating the augmentation of the abdominal aorta's diameter as assessed by transabdominal ultrasound imaging. Importantly, IH with Ang II augmented aortic elastin degradation and the expression of matrix metalloproteinases (MMPs), mainly MMP8, MMP12, and a disintegrin and metalloproteinase-17 (ADAM17) as measured by histology and immunohistochemistry. Mechanistically, IH increased the activities of MMP2, MMP8, MMP9, MMP12, and ADAM17, while reducing the expression of the MMP regulator reversion-inducing cysteine-rich protein with Kazal motifs (RECK) in cultured SMCs. Aortic samples from human AAA were associated with decreased RECK and increased expression of ADAM17 and MMPs. These data suggest that IH facilitates AAA development when additional stressors are superimposed and that this occurs in association with an increased presence of aortic MMPs and ADAM17, potentially due to IH-induced modulation of RECK expression. These findings support a plausible synergistic link between OSA and AAA and provide a better understanding of the molecular mechanisms underlying the pathogenesis of AAA. NEW & NOTEWORTHY IH facilitates Ang II-induced abdominal aortic diameter expansion and AAA development in C57BL/6J male mice. IH upregulates the expression of specific MMPs such as MMP8, MMP12, and ADAM17. IH directly suppresses RECK expression and increases MMPs activity in SMCs. Human AAA tissues exhibit a downregulation of RECK and an upregulation of ADAM17 and MMPs.

Background: Inflammation is a key component in the development of abdominal aortic aneurysm (AAA), yet insights into the roles of immune cells and their interactions in this process are limited., Methods: Using single-cell RNA transcriptomic analysis, we deconstructed the CD45 + cell population in elastase-induced murine AAA at the single-cell level. We isolated each group of immune cells from murine AAA tissue at different time points and divided them into several subtypes, listed the remarkable differentially expressed genes, explored the developmental trajectories of immune cells, and demonstrated the interactions among them., Results: Our findings reveal significant differences in several immune cell subsets, including macrophages, dendritic cells, and T cells, within the AAA microenvironment compared with the normal aorta. Especially, conventional dendritic cell type 1 exclusively existed in the AAA tissue rather than the normal aortas. Via CellChat analysis, we identified several intercellular communication pathways like visfatin, which targets monocyte differentiation and neutrophil extracellular trap-mediated interaction between neutrophils and dendritic cells, which might contribute to AAA development. Some of these pathways were validated in human AAA., Conclusions: Despite the absence of external pathogenic stimuli, AAA tissues develop a complex inflammatory microenvironment involving numerous immune cells. In-depth studies of the inflammatory network shall provide new strategies for patients with AAA., Competing Interests: None.

Background: Abdominal aortic aneurysms expand over time and increase the risk of fatal ruptures. To predict expansion, the isolated assessment of 18 F-fluorodeoxyglucose (FDG) and sodium fluoride (NaF) uptake or calcification volume in aneurysms has been investigated with variability in results. We systematically evaluated whether 18 F-FDG and 18 F-NaF uptake was predictive of abdominal aortic aneurysm expansion., Methods: Seventy-four male Sprague-Dawley rat abdominal aortic aneurysm models were imaged using positron emission tomography-computed tomography with 18 F-FDG and 18 F-NaF at 1, 2, 4, 6, and 8 weeks after CaCl 2 or saline stimulation. In the 1-week cohort (n=25), the correlation between 18 F-FDG or 18 F-NaF uptake and pathological markers was investigated. In the time course cohort (n=49), animals received either atorvastatin, losartan, aldactone, or risedronate to assess the effect of these drugs, and the relationship between aortic size and sequential 18 F-FDG and 18 F-NaF uptake or calcification volume was examined., Results: In the 1-week cohort, the maximum standard unit value of 18 F-FDG and 18 F-NaF uptake correlated with CD68- (r=0.82; P =0.001) and von Kossa staining-positive areas (r=0.89; P <0.001), respectively. In the time course cohort, 18 F-FDG and 18 F-NaF uptake changed in a time-dependent manner and drugs attenuated this uptake. Specifically, 18 F-FDG showed high uptake at weeks 1 and 2, whereas a high 18 F-NaF uptake was noted throughout the study period. Atorvastatin and risedronate showed a decreased and increased aortic size, respectively. The final aortic area correlated well with 18 F-FDG and 18 F-NaF uptake and calcification volume, especially at 1 and 2 weeks ( 18 F-NaF [1 week]: r=0.61, 18 F-FDG [2 weeks]: r=0.51, calcification volume [1 week]: r=0.59; P <0.001). Multiple linear regression analysis showed that the combination of these factors predicted the final aortic size, with 18 F-NaF uptake at 1 week being the strongest predictor., Conclusions: The uptake of 18 F-NaF and 18 F-FDG and the calcification volume at appropriate times correlated with the development of abdominal aortic aneurysms, with 18 F-NaF uptake being the strongest predictor., Competing Interests: None.

Abdominal aortic aneurysm (AAA) is a dangerous condition affecting the aorta. Macrophage pyroptosis, phenotypic transformation, and apoptosis of aortic smooth muscle cells (ASMCs) are pivotal mechanisms in AAA pathogenesis. This study explores how Gasdermin B (GSDMB) regulates macrophage non-canonical pyroptosis and its impact on the phenotypic transformation and apoptosis of ASMCs, thereby unveiling the role of GSDMB in AAA pathogenesis. Immunofluorescence analysis was used to assess the expression levels and localization of GSDMB, cysteinyl aspartate-specific protease-4 (Caspase-4), and N-terminal of cleaved GSDMD (N-GSDMD) in AAA tissues. A cell model that mimics macrophage non-canonical pyroptosis was established by treating THP-1 cells with lipopolysaccharide (LPS). THP-1 cells with reduced or increased GSDMB were generated using small interfering RNA (siRNA) or plasmids. Co-culture experiments involving THP-1 cells and HASMCs were conducted to explore the impact of GSDMB on HASMCs. The mitochondrial reactive oxygen species (mtROS) scavenger Mito-TEMPO lowered mtROS levels in THP-1 cells. Our findings revealed that GSDMB was significantly upregulated in AAA macrophages, which was accompanied by robust non-canonical pyroptosis. THP-1 cells showed non-canonical pyroptosis in response to LPS, which was accompanied by an increase in GSDMB. Further research demonstrated that altering GSDMB, either by knockdown or overexpression, can affect macrophage non-canonical pyroptosis as well as the phenotypic transformation and apoptosis of HASMCs. LPS-induced non-canonical pyroptosis in THP-1 cells was associated with an increase in mtROS, whereas Mito-TEMPO effectively decreased non-canonical pyroptosis and the expression of GSDMB. These findings suggest that GSDMB plays a role in AAA macrophage non-canonical pyroptosis, which influences the phenotypic transformation and apoptosis of HASMCs. The mtROS-Dynamin-Related Protein 1 (Drp1) axis is likely to regulate the GSDMB-mediated non-canonical pyroptosis., Competing Interests: Declaration of competing interest None., (Copyright © 2024. Published by Elsevier Inc.)

Imbalance of proinflammatory and anti-inflammatory responses plays a crucial role in the progression of abdominal aortic aneurysms. ILF3, a known modulator of the innate immune response, is involved in cardiovascular diseases. This study aims to investigate the role of ILF3 in abdominal aortic aneurysm formation. Here, we use multi-omics analyzes, transgenic male mice, and multiplex immunohistochemistry to unravel the underlying involvement of ILF3 in abdominal aortic aneurysms. The results show that macrophage ILF3 deficiency attenuates abdominal aortic aneurysm progression, while elevated macrophage ILF3 exacerbates abdominal aortic aneurysm lesions. Mechanistically, we reveal that macrophagic ILF3 increases NF-κB activity by hastening the decay of p105 mRNA, leading to amplified inflammation in macrophages. Meanwhile, ILF3 represses the anti-inflammatory action by inhibiting the Keap1-Nrf2 signaling pathway through facilitating the ILF3/eIF4A1 complex-mediated enhancement of Keap1 translational efficiency. Moreover, Bardoxolone Methyl treatment alleviates the severity of abdominal aortic aneurysm lesions in the context of elevated ILF3 expression. Together, our findings underscore the significance of macrophage ILF3 in abdominal aortic aneurysm development and suggest its potential as a promising therapeutic target for abdominal aortic aneurysms., (© 2024. The Author(s).)

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., Competing Interests: Conflict of interest The authors have declared no conflict of interest., (Copyright © 2024 Elsevier Inc. All rights reserved.)

This study unveils the pivotal roles of taurine metabolic reprogramming and its implications in the development and progression of Abdominal Aortic Aneurysm (AAA). Leveraging an integrated approach that combines single-cell RNA sequencing (scRNA-seq) and Weighted Gene Co-expression Network Analysis (WGCNA), our research investigates the intricate transcriptional and gene expression dynamics crucial to AAA. Our findings uniquely link metabolic shifts to the integrity of the extracellular matrix (ECM) and the functionality of smooth muscle cells (SMCs), key elements in the pathology of AAA. Utilizing scRNA-seq data from a mouse model (GSE152583 dataset), we identified critical alterations in cellular composition during AAA progression, particularly highlighting shifts in fibroblasts and inflammatory cells. Concurrently, WGCNA of human AAA tissue samples has outlined distinct gene expression patterns correlated with disease severity and progression, offering comprehensive insights into both molecular and cellular disease mechanisms. Moreover, this study introduces innovative metabolic profiling techniques to identify differential metabolites in AAA, integrating extensive metabolomic analyses with pathway enrichment strategies. This novel approach has pinpointed potential biomarkers and therapeutic targets, notably within taurine metabolism pathways, crucial for crafting non-surgical interventions. By merging state-of-the-art bioinformatics with thorough molecular analysis, our study not only enhances the understanding of AAA's complex pathophysiology but also catalyzes the development of targeted therapeutic strategies. This research represents a significant advancement in the molecular characterization of AAA, with substantial implications for its future diagnosis and treatment strategies., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Background: Mesenchymal stromal cell (MSC)-derived exosomes (MSC-Exo) have been recognized for their significant role in regulating macrophage polarization, a process crucial to the pathogenesis of abdominal aortic aneurysm (AAA). However, the therapeutic effects of MSC-Exo on AAA remain largely unexplored. Therefore, this study aimed to investigate the functional and mechanistic aspects of MSC-Exo in the progression of AAA., Methods: The MSC-derived exosomes were characterized using Transmission Electron Microscopy, Nanoparticle Tracking Analysis, and Western blotting. An experimental mouse model of AAA was established through the administration of angiotensin II (Ang II) in male apoe -/- mice and calcium chloride (CaCl 2 ) in male C57/B6 mice, with subsequent tail vein injection of exosomes to evaluate their efficacy against AAA. Macrophage polarization was assessed using immunofluorescence staining and WB analysis. Mechanistic analysis was performed using 4D Label-free Proteomics analysis., Results: We found that intravenous administration of MSC-Exo induced M2 polarization of macrophages within an inflammatory environment, effectively impeding AAA development in Ang II or CaCl 2 -induced AAA model. The therapeutic efficacy of MSC-Exo treatment was dependent on the presence of macrophages. Mechanistically, MSC-Exo suppressed the levels of cluster of differentiation 74 (CD74), modulating macrophage polarization through the TSC2-mTOR-AKT pathway. These findings highlight the potential of MSC-Exo as a therapeutic strategy for AAA by modulating macrophage polarization., (© 2024. The Author(s).)

Background: The long isoform of the Wnk1 (with-no-lysine [K] kinase 1) is a ubiquitous serine/threonine kinase, but its role in vascular smooth muscle cells (VSMCs) pathophysiology remains unknown., Methods: AngII (angiotensin II) was infused in Apoe -/- to induce experimental aortic aneurysm. Mice carrying an Sm22-Cre allele were cross-bred with mice carrying a floxed Wnk1 allele to specifically investigate the functional role of Wnk1 in VSMCs., Results: Single-cell RNA-sequencing of the aneurysmal abdominal aorta from AngII-infused Apoe -/- mice revealed that VSMCs that did not express Wnk1 showed lower expression of contractile phenotype markers and increased inflammatory activity. Interestingly, WNK1 gene expression in VSMCs was decreased in human abdominal aortic aneurysm. Wnk1 -deficient VSMCs lost their contractile function and exhibited a proinflammatory phenotype, characterized by the production of matrix metalloproteases, as well as cytokines and chemokines, which contributed to local accumulation of inflammatory macrophages, Ly6C hi monocytes, and γδ T cells. Sm22Cre+Wnk1 lox/lox mice spontaneously developed aortitis in the infrarenal abdominal aorta, which extended to the thoracic area over time without any negative effect on long-term survival. AngII infusion in Sm22Cre+Wnk1 lox/lox mice aggravated the aortic disease, with the formation of lethal abdominal aortic aneurysms. Pharmacological blockade of γδ T-cell recruitment using neutralizing anti-CXCL9 (anti-CXC motif chemokine ligand 9) antibody treatment, or of monocyte/macrophage using Ki20227, a selective inhibitor of CSF1 receptor, attenuated aortitis. Wnk1 deletion in VSMCs led to aortic wall remodeling with destruction of elastin layers, increased collagen content, and enhanced local TGF-β (transforming growth factor-beta) 1 expression. Finally, in vivo TGF-β blockade using neutralizing anti-TGF-β antibody promoted saccular aneurysm formation and aorta rupture in Sm22 Cre+ Wnk1 lox/lox mice but not in control animals., Conclusion: Wnk1 is a key regulator of VSMC function. Wnk1 deletion promotes VSMC phenotype switch toward a pathogenic proinflammatory phenotype, orchestrating deleterious vascular remodeling and spontaneous severe aortitis in mice., Competing Interests: None.

Aortic aneurysms, particularly abdominal aortic aneurysms (AAAs), exhibit sex differences, with higher prevalence and severity in males than females, both in humans and experimental mouse models. In fact, male sex has been considered as the most potent nonmodifiable risk factor for AAA. Currently, there are no medications approved for the treatment of aortic aneurysms, despite the high lethality of ruptured aneurysms, which account for nearly 2% of all deaths. Moreover, the underlying molecular mechanisms mediating the sexual dimorphism of aortic aneurysms remain largely unknown. In this issue of the JCI, Mu et al. revealed a mechanism by which androgens, male sex hormones, exacerbate aortic aneurysms by suppressing programmed cell death protein 1 (PD-1) expression in T cells in an aldosterone and high salt-induced aortic aneurysm mouse model.

Background: Exposure to ionizing radiation has been linked to cardiovascular diseases. However, the impact of moderate doses of radiation on abdominal aortic aneurysm (AAA) remains unknown., Methods: Angiotensin II-infused Apoe-/- mice were irradiated (acute, 1 Gray) either 3 days before (Day-3) or 1 day after (Day+1) pomp implantation. Isolated primary aortic vascular smooth muscle cells (VSMCs) were irradiated (acute 1 Gray) for mechanistic studies and functional testing in vitro., Results: Day-3 and Day+1 irradiation resulted in a significant reduction in aorta dilation (Control: 1.39+/-0.12; Day-3: 1.12+/-0.11; Day+1: 1.15+/-0.08 mm, P<0.001) and AAA incidence (Control: 81.0%; Day-3: 33.3%, Day+1: 53.3%) compared to the non-irradiated group. Day-3 and Day+1 irradiation led to an increase in collagen content in the adventitia (Thickness control: 23.64+/-2.9; Day-3: 54.39+/-15.5; Day+1 37.55+/-10.8 mm, P = 0.006). However, the underlying protective mechanisms were different between Day-3 and Day+1 groups. Irradiation before Angiotensin II (AngII) infusion mainly modulated vascular smooth muscle cell (VSMC) phenotype with a decrease in contractile profile and enhanced proliferative and migratory activity. Irradiation after AngII infusion led to an increase in macrophage content with a local anti-inflammatory phenotype characterized by the upregulation of M2-like gene and IL-10 expression., Conclusion: Moderate doses of ionizing radiation mitigate AAA either through VSCM phenotype or inflammation modulation, depending on the time of irradiation., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Riazi et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Abdominal aortic aneurysm (AAA) is a highly lethal cardiovascular disease that currently lacks effective pharmacological treatment given the complex pathophysiology of the disease. Here, single-cell RNA-sequencing data from patients with AAA and a mouse model are analyzed, which reveals pivotal pathological changes, including the M1-like polarization of macrophages and the loss of contractile function in smooth muscle cells (SMCs). Both cell types express the integrin αvβ3, allowing for their dual targeting with a single rationally designed molecule. To this end, a biocompatible nanodrug, which is termed EVMS@R-HNC, that consists of the multifunctional drug everolimus (EVMS) encapsulated by the hepatitis B virus core protein modifies to contain the RGD sequence to specifically bind to integrin αvβ3 is designed. Both in vitro and in vivo results show that EVMS@R-HNC can target macrophages as well as SMCs. Upon binding of the nanodrug, the EVMS is released intracellularly where it exhibits multiple functions, including inhibiting M1 macrophage polarization, thereby suppressing the self-propagating inflammatory cascade and immune microenvironment imbalance, while preserving the normal contractile function of SMCs. Collectively, these results suggest that EVMS@R-HNC presents a highly promising therapeutic approach for the management of AAA., (© 2024 Wiley‐VCH GmbH.)

Abdominal aortic aneurysm (AAA) is a common and potentially life-threatening condition. Chronic aortic inflammation is closely associated with the pathogenesis of AAA. Nerve injury-induced protein 1 (NINJ1) is increasingly acknowledged as a significant regulator of the inflammatory process. However, the precise involvement of NINJ1 in AAA formation remains largely unexplored. The present study finds that the expression level of NINJ1 is elevated, along with the specific expression level in macrophages within human and angiotensin II (Ang II)-induced murine AAA lesions. Furthermore, Ninj1 flox/flox and Ninj1 flox/flox Lyz2-Cre mice on an ApoE -/- background are generated, and macrophage NINJ1 deficiency inhibits AAA formation and reduces macrophage infiltration in mice infused with Ang II. Consistently, in vitro suppressing the expression level of NINJ1 in macrophages significantly restricts macrophage adhesion and migration, while attenuating macrophage pro-inflammatory responses. Bulk RNA-sequencing and pathway analysis uncover that NINJ1 can modulate macrophage infiltration through the TLR4/NF-κB/CCR2 signaling pathway. Protein-protein interaction analysis indicates that NINJ1 can activate TLR4 by competitively binding with ANXA2, an inhibitory interacting protein of TLR4. These findings reveal that NINJ1 can modulate AAA formation by promoting macrophage infiltration and pro-inflammatory responses, highlighting the potential of NINJ1 as a therapeutic target for AAA., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

Background: Abdominal aortic aneurysm (AAA) is a life-threatening aortic disease, and to date, there are currently no effective pharmacological treatments to address this condition. Activation of cytosolic DNA sensing adaptor stimulator of interferon genes (STING) signaling is a crucial mechanism in AAA formation., Purpose: This study investigated pterostilbene (Pt), a naturally occurring polyphenol and resveratrol analogue, as a STING inhibitor for preventing AAA., Methods: We evaluated the effect of Pt on AAA formation in angiotensin II (AngII)-infused apolipoprotein E-deficient (ApoE -/- ) mice. We used histological analysis, MMP activity measurement, western blot, and immunohistochemistry to detect AAA formation and development. We applied RNA sequencing, molecular docking, cellular thermal shift assay (CETSA) and functional studies to dissect the molecular mechanism of Pt-regulating KEAP1-Nrf2-STING signaling. We conditionally knocked down Nrf2 in vascular smooth muscle cells (VSMCs) in vivo to investigate its role in Pt-mediated protective effects on AAA., Results: Pt effectively blocked the formation of AAA in AngII-infused ApoE -/- mice. Whole transcriptome sequencing analysis revealed that nuclear factor erythroid 2-related factor 2 (Nrf2) and STING pathway in VSMCs were linked to the anti-AAA effects of pterostilbene. Mechanistically, Pt upregulated Nrf2 target genes (e.g., HO-1 and NQO1) through activation of the KEAP1/Nrf2 signaling, which restricted the immunostimulatory axis of mtDNA-STING-TBK1-NF-κB, thereby alleviating VSMC inflammation and preserving the VSMC contractile phenotype. Subsequently, molecular docking and CETSA revealed a binding mode between Pt and KEAP1/Nrf2. Intriguingly, the inhibitory effect of Pt on STING signaling and the protective role of Pt in AAA were largely abrogated by VSMC-specific Nrf2 knockdown in mice., Conclusion: Collectively, naturally derived Pt shows promising efficacy for the treatment of AAA by targeting the KEAP1-Nrf2-STING axis in VSMCs., Competing Interests: Declaration of competing interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Elsevier GmbH. All rights reserved.)

Abdominal aortic aneurysm (AAA) is one of the most life-threatening cardiovascular diseases; however, effective drug treatments are still lacking. The formation of neutrophil extracellular traps (NETs) has been shown to be a crucial trigger of AAA, and identifying upstream regulatory targets is thus key to discovering therapeutic agents for AAA. We revealed that phosphoinositide-3-kinase γ (PI3Kγ) acted as an upstream regulatory molecule and that PI3Kγ inhibition reduced NET formation and aortic wall inflammation, thereby markedly ameliorating AAA. However, the mechanism of NET formation regulated by PI3Kγ remains unclear. In this study, we showed that PI3Kγ deficiency inactivated the noncanonical pyroptosis pathway, which suppressed downstream NET formation. In addition, PI3Kγ regulation of noncanonical pyroptosis was dependent on cyclic AMP/protein kinase A signaling. These results clarify the molecular mechanism and crosstalk between PI3Kγ and NETosis in the development of AAA, potentially facilitating the discovery of therapeutic options for AAA.

Abdominal aortic aneurysm (AAA) is a life-threatening disease characterized by extensive membrane destruction in the vascular wall that is closely associated with vascular smooth muscle cell (VSMC) phenotypic switching. A thorough understanding of the changes in regulatory factors during VSMC phenotypic switching is essential for managing AAA therapy. In this study, we revealed the impact of NRF2 on the modulation of VSMC phenotype and the development of AAA based on single-cell RNA sequencing analysis. By utilizing a murine model of VSMC-specific knockout of nuclear factor E2-related factor 2 (NRF2), we observed that the absence of NRF2 in VSMCs exacerbated AAA formation in an angiotensin II-induced AAA model. The downregulation of NRF2 promoted VSMC phenotypic switching, leading to an enhanced inflammatory response. Through genome-wide transcriptome analysis and loss- or gain-of-function experiments, we discovered that NRF2 upregulated the expression of VSMC contractile phenotype-specific genes by facilitating microRNA-145 (miR-145) expression. Our data identified NRF2 as a novel regulator involved in maintaining the VSMC contractile phenotype while also influencing AAA formation through an miR-145-dependent regulatory mechanism., (© 2024 Federation of American Societies for Experimental Biology.)

There is a pressing need for alternative medical treatments for abdominal aortic aneurysms (AAAs). Mesenchymal regenerative cells derived from adipose tissue (ADRCs) have shown potential in modulating the inflammation and immune responses that drive AAA progression. We hypothesized that ADRCs could reduce inflammation and preserve vascular integrity, potentially slowing the progression of AAA. In our study, subcutaneous adipose tissue was harvested from male Sprague Dawley rats, from which ADRCs were isolated. AAA was induced in these rats using intraluminal porcine pancreatic elastase, followed by intravenous administration of either ADRCs (10 6 cells) or saline (0.1 mL). We monitored the progression of AAA through weekly ultrasound, and the rats were sacrificed on day 28 for histological analysis. Our results showed no significant difference in the inner abdominal aortic diameter at day 28 between the control group (172% ± 73%, n = 17) and the ADRC-treated group (181% ± 75%, n = 15). Histological analyses of AAA cross-sections also revealed no significant difference in the infiltration of neutrophils or macrophages between the two groups. Furthermore, the integrity and content of elastin in the tunica media were similar between groups. These findings indicate that a single injection of ADRCs does not inhibit the development of AAA in rats in a randomized blinded study.

Abdominal aortic aneurysm has a high heritability and often co-occurs with other cardiometabolic disorders, suggesting shared genetic susceptibility. We investigate this commonality leveraging recent GWAS studies of abdominal aortic aneurysm and 32 cardiometabolic traits. We find significant genetic correlations between abdominal aortic aneurysm and 21 of the cardiometabolic traits investigated, including causal relationships with coronary artery disease, hypertension, lipid traits, and blood pressure. For each trait pair, we identify shared causal variants, genes, and pathways, revealing that cholesterol metabolism and inflammation are shared most prominently. Additionally, we show the tissue and cell type specificity in the shared signals, with strong enrichment across traits in the liver, arteries, adipose tissues, macrophages, adipocytes, and fibroblasts. Finally, we leverage drug-gene databases to identify several lipid-lowering drugs and antioxidants with high potential to treat abdominal aortic aneurysm with comorbidities. Our study provides insight into the shared genetic mechanism between abdominal aortic aneurysm and cardiometabolic traits, and identifies potential targets for pharmacological intervention., (© 2024. The Author(s).)

Tumor endothelial marker 1 (TEM1), an activated mesenchymal cell marker, is implicated in tissue remodeling and repair. Herein, we investigated the role and therapeutic implications of TEM1 in abdominal aortic aneurysm (AAA), a potentially life-threatening aortic disease characterized by vascular inflammation and matrix turnover. Characterization of human AAA revealed increased TEM1 expression derived mainly from medial vascular smooth muscle cells (VSMCs) and adventitial fibroblasts. Bioinformatics analysis demonstrated the association between TEM1-expressing VSMCs and fibroblasts and collagen gene expression. Consistently, collagen content and TEM1 expressed by VSMCs and fibroblasts were increased during CaCl 2 -induced AAA formation in mice. TEM1 silencing in VSMCs and fibroblasts inhibited transforming growth factor-β1-induced phenotypic change, SMAD2 phosphorylation, and COL1A1 gene expression. Also, Tem1 deficiency reduced collagen synthesis and exacerbated CaCl 2 -induced AAA formation in mice without disturbing elastin destruction and inflammatory responses. In contrast, rTEM1 promoted phenotypic change and COL1A1 gene expression through SMAD2 phosphorylation in VSMCs and fibroblasts. Treatment with rTEM1 enhanced collagen synthesis, attenuated elastin fragmentation, and inhibited CaCl 2 -induced and angiotensin II-infused AAA formation. In summary, TEM1 in resident stromal cells regulates collagen synthesis to counteract aortic wall failure during AAA formation. Matrix integrity restored by rTEM1 treatment may hold therapeutic potential against AAA., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Background: Abdominal aortic aneurysm (AAA) is a severe aortic disease without effective pharmacological approaches. The nuclear hormone receptor LXRα (liver X receptor α), encoded by the NR1H3 gene, serves as a critical transcriptional mediator linked to several vascular pathologies, but its role in AAA remains elusive., Methods: Through integrated analyses of human and murine AAA gene expression microarray data sets, we identified NR1H3 as a candidate gene regulating AAA formation. To investigate the role of LXRα in AAA formation, we used global Nr1h3 -knockout and vascular smooth muscle cell-specific Nr1h3 -knockout mice in 2 AAA mouse models induced with angiotensin II (1000 ng·kg·min; 28 days) or calcium chloride (CaCl 2 ; 0.5 mol/L; 42 days)., Results: Upregulated LXRα was observed in the aortas of patients with AAA and in angiotensin II- or CaCl 2 -treated mice. Global or vascular smooth muscle cell-specific Nr1h3 knockout inhibited AAA formation in 2 mouse models. Loss of LXRα function prevented extracellular matrix degeneration, inflammation, and vascular smooth muscle cell phenotypic switching. Uhrf1 , an epigenetic master regulator, was identified as a direct target gene of LXRα by integrated analysis of transcriptome sequencing and chromatin immunoprecipitation sequencing. Susceptibility to AAA development was consistently enhanced by UHRF1 (ubiquitin-like containing PHD and RING finger domains 1) in both angiotensin II- and CaCl 2 -induced mouse models. We then determined the CpG methylation status and promoter accessibility of UHRF1-mediated genes using CUT&Tag (cleavage under targets and tagmentation), RRBS (reduced representation bisulfite sequencing), and ATAC-seq (assay for transposase-accessible chromatin with sequencing) in vascular smooth muscle cells, which revealed that the recruitment of UHRF1 to the promoter of miR-26b led to DNA hypermethylation accompanied by relatively closed chromatin states, and caused downregulation of miR-26b expression in AAA. Regarding clinical significance, we found that underexpression of miR-26b-3p correlated with high risk in patients with AAA. Maintaining miR-26b-3p expression prevented AAA progression and alleviated the overall pathological process., Conclusions: Our study reveals a pivotal role of the LXRα/UHRF1/miR-26b-3p axis in AAA and provides potential biomarkers and therapeutic targets for AAA., Competing Interests: Disclosures None.

Purpose of Review: Abdominal aortic aneurysm refers to a serious medical condition that can cause the irreversible expansion of the abdominal aorta, which can lead to ruptures that are associated with up to 80% mortality. Currently, surgical and interventional procedures are the only treatment options available for treating abdominal aortic aneurysm patients. In this review, we focus on the upstream and downstream molecules of the microRNA-related signaling pathways and discuss the roles, mechanisms, and targets of microRNAs in abdominal aortic aneurysm modulation to provide novel insights for precise and targeted drug therapy for the vast number of abdominal aortic aneurysm patients., Recent Findings: Recent studies have highlighted that microRNAs, which are emerging as novel regulators of gene expression, are involved in the biological activities of regulating abdominal aortic aneurysms. Accumulating studies suggested that microRNAs modulate abdominal aortic aneurysm development through various signaling pathways that are yet to be comprehensively summarized. A total of six signaling pathways (NF-κB signaling pathway, PI3K/AKT signaling pathway, MAPK signaling pathway, TGF-β signaling pathway, Wnt signaling pathway, and P53/P21 signaling pathway), and a total of 19 miRNAs are intimately associated with the biological properties of abdominal aortic aneurysm through targeting various essential molecules. MicroRNAs modulate the formation, progression, and rupture of abdominal aortic aneurysm by regulating smooth muscle cell proliferation and phenotype change, vascular inflammation and endothelium function, and extracellular matrix remodeling. Because of the broad crosstalk among signaling pathways, a comprehensive analysis of miRNA-mediated signaling pathways is necessary to construct a well-rounded upstream and downstream regulatory network for future basic and clinical research of AAA therapy., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Peroxynitrite (ONOO - ) and cell plasma membrane (CPM) are two key factors in cell pyroptosis during the progression of abdominal aortic aneurysm (AAA). However, their combined temporal and spatial roles in initiating AAA pathogenesis remain unclear. Herein, we developed a two-photon fluorescence probe, BH-Vis, enabling real-time dynamic detection of CPM and ONOO - changes, and revealing their interplay in AAA. BH-Vis precisely targets CPM with reduced red fluorescence intensity correlating with diminished CPM tension. Concurrently, a blue shift of the fluorescence signal of BH-Vis occurs in response to ONOO - offering a reliable ratiometric detection mode with enhanced accuracy by minimizing external testing variables. More importantly, two photon confocal imaging with palmitic acid (PA) and ganglioside (GM1) manipulation, which modulating cell pyroptosis, showcases reliable fluorescence fluctuations. This groundbreaking application of BH-Vis in a mouse AAA model demonstrates its significant potential for accurately identifying cell pyroptosis levels during AAA development., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Background: Abdominal aortic aneurysm (AAA) is a complex vascular disorder characterized by the progressive dilation of the abdominal aorta, with a high risk of rupture and mortality. Understanding the cellular interactions and molecular mechanisms underlying AAA development is critical for identifying potential therapeutic targets., Methods: This study utilized datasets GSE197748, GSE164678 and GSE183464 from the GEO database, encompassing bulk and single-cell RNA sequencing data from AAA and control samples. We performed principal component analysis, differential expression analysis, and functional enrichment analysis to identify key pathways involved in AAA. Cell-cell interactions were investigated using CellPhoneDB, focusing on fibroblasts, vascular smooth muscle cells (VSMCs), and macrophages. We further validated our findings using a mouse model of AAA induced by porcine pancreatic enzyme infusion, followed by gene expression analysis and co-immunoprecipitation experiments., Results: Our analysis revealed significant alterations in gene expression profiles between AAA and control samples, with a pronounced immune response and cell adhesion pathways being implicated. Single-cell RNA sequencing data highlighted an increased proportion of pro-inflammatory macrophages, along with changes in the composition of fibroblasts and VSMCs in AAA. CellPhoneDB analysis identified critical ligand-receptor interactions, notably collagen type I alpha 1 chain (COL1A1)/COL1A2-CD18 and thrombospondin 1 (THBS1)-CD3, suggesting complex communication networks between fibroblasts and VSMCs. In vivo experiments confirmed the upregulation of these genes in AAA mice and demonstrated the functional interaction between COL1A1/COL1A2 and CD18., Conclusion: The interaction between fibroblasts and VSMCs, mediated by specific ligand-receptor pairs such as COL1A1/COL1A2-CD18 and THBS1-CD3, plays a pivotal role in AAA pathogenesis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

This study aimed to explore whether m6A modification affects the biogenesis of circRBM33, which is involved in the progression of abdominal aortic aneurysm (AAA). For in vitro experiments, vascular smooth muscle cells (VSMCs) were treated with Ang II. MeRIP‒PCR was used to assess m6A modification of circRBM33. Gene expression was measured using RT‒qPCR and Western blotting. For in vivo experiments, a mouse model of AAA was established via Ang II infusion. HE, Sirius Red and TUNEL staining was performed to evaluate pathological changes and cell apoptosis in aortic vessels. The results showed that the m6A level of circRBM33 was abnormally increased in Ang II-induced VSMCs. In addition, METTL3 positively regulated circRBM33 expression. YTHDC1 deficiency decreased circRBM33 expression but had no effect on RBM33 mRNA expression. Notably, neither METTL3 nor YTHDC1 influenced the stability of circRBM33 or RBM33 mRNA. The interaction between circRBM33 and METTL3/YTHDC1 was verified by RIP analysis. Moreover, the Ang II-induced increase in circRBM33 expression was reversed by cycloleucine (an inhibitor of m6A methylation). Importantly, the m6A modification and expression of circRBM33 in the circRBM33-m6A-mut2-expressing VSMCs were not altered by METTL3 silencing. Mechanistically, METTL3/YTHDC1 modulates the biogenesis of circRBM33 in an m6A-dependent manner. In addition, circRBM33 knockdown alleviated AAA by reducing ECM degradation in the Ang II-infused mice. In conclusion, this study demonstrated that METTL3/YTHDC1-mediated m6A modification modulates the biogenesis of circRBM33 from exons of the RBM33 gene. Moreover, knockdown of circRBM33 alleviated AAA by reducing ECM degradation, which may provide a novel therapeutic strategy for treating AAA.

Purpose of Review: There are no current drug therapies to limit abdominal aortic aneurysm (AAA) growth. This review summarizes evidence suggesting that inhibiting proprotein convertase subtilisin/kexin type 9 (PCSK9) may be a drug target to limit AAA growth., Recent Findings: Mendelian randomization studies suggest that raised LDL and non-HDL-cholesterol are causal in AAA formation. PCSK9 was reported to be upregulated in human AAA samples compared to aortic samples from organ donors. PCSK9 gain of function viral vectors promoted aortic expansion in C57BL/6 mice infused with angiotensin II. The effect of altering PCSK9 expression in the aortic perfusion elastase model was reported to be inconsistent. Mutations in the gene encoding PCSK9, which increase serum cholesterol, were associated with increased risk of human AAA. Patients with AAA also have a high risk of cardiovascular death, myocardial infarction and stroke. Recent research suggests that PCSK9 inhibition would substantially reduce the risk of these events., Summary: Past research suggests that drugs that inhibit PCSK9 have potential as a novel therapy for AAA to both limit aneurysm growth and reduce risk of cardiovascular events. A large multinational randomized controlled trial is needed to test if PCSK9 inhibition limits AAA growth and cardiovascular events., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Objectives: Inflammatory proteins are implicated in the progression of abdominal aortic aneurysms (AAA); however, it remains debated whether they are causal or consequential. This study aimed to assess the influence of circulating inflammatory proteins on AAA via two-sample Mendelian randomization (MR) and colocalization analysis., Methods: Summary data on 91 circulating inflammatory protein levels were extracted from a comprehensive protein quantitative trait loci (pQTL) study involving 14,824 individuals. Genetic associations with AAA were derived from the FinnGen study (3,869 cases and 381,977 controls). MR analysis was conducted to assess the relationships between proteins and AAA risk. Colocalization analysis was employed to explore potential shared causal variants between identified proteins and AAA., Results: Using a two-sample bidirectional MR study, our findings suggested that genetically predicted elevated levels of TGFB1 (OR = 1.21, P = 0.003), SIRT2 (OR = 1.196, P = 0.031) and TNFSF14 (OR = 1.129, P = 0.034) were linked to an increased risk of AAA. Conversely, genetically predicted higher levels of CD40 (OR = 0.912, P = 0.049), IL2RB (OR = 0.839, P = 0.028) and KITLG (OR = 0.827, P = 0.008) were associated with a decreased risk of AAA. Colocalization analyses supported the association of TGFB1 and SIRT2 levels with AAA risk., Conclusions: The proteome-wide MR and colocalization study identified TGFB1 and SIRT2 as being associated with the risk of AAA, warranting further investigation as potential therapeutic targets., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Abdominal aortic aneurysm (AAA) is a cardiovascular disease that seriously threatens human health and brings huge economic burden. At present, its pathogenesis remains unclear and its treatment is limited to surgical treatment. With the deepening and analysis of studies on the mechanism of ferroptosis, a new idea has been provided for the clinical management of AAA patients, including diagnosis, treatment and prevention. Therefore, this paper aims to construct a competitive endogenous RNA (ceRNA) regulatory axis based on ferroptosis to preliminarily explore the pathogenesis and potential therapeutic targets of AAA. We obtained upregulated and downregulated ferroptosis-related DEGs (FRGs) from GSE144431 dataset and 60 known ferroptosis-related genes. Pearson correlation analysis was used to find aldoketone reductase 1C (AKR1C1) in AAA samples. Enrichment analysis of these genes was performed via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Correlation test between immune cells and AKR1C1 was investigated through single-sample gene set enrichment analysis (ssGSEA). The AKR1C1-miRNA pairs were predicted by the TargetScan database and miRWalk database. Circular RNA (CircRNA)-miRNA pairs were selected by the CircInteractome database. Overlapping miRNA between circRNA-miRNA and AKR1C1-miRNA pairs was visualized by Venn diagram. Finally, the circRNA-miRNA-mRNA axis was constructed by searching for upstream circRNA and downstream mRNA of overlapping miRNA. Only one downregulated AKR1C1 gene was found in GSE144431 and 60 ferroptosis-related genes. Functional Enrichment and Pathway Analysis of AKR1C1-related genes were further explored, and it was observed that they were mainly enriched in "response to oxidative stress," "glutathione biosynthetic process" and "nonribosomal peptide biosynthetic process," "Ferroptosis," "Glutathione metabolism" and "Chemical carcinogenesis-reactive oxygen species." They were also found to be significantly associated with most immune cells, including Activated Dendritic cells, CD56dim Natural killer cells, Gamma Delta T cells, Immature B cells, Plasmacytoid dendritic cell, Type 2 T helper cell, Activated CD4 T cell and Type 1 T helper cell. Has&#95;circ&#95;0005073-miRNA-543 and AKR1C1-miRNA-543 were identified by Online Database analysis. Therefore, we have established the has&#95;circ&#95;0005073/miRNA-543/AKR1C1 axis in AAA. We found AKR1C1 was differentially expressed between normal and AAA groups. Based on AKR1C1, we constructed the has&#95;circ&#95;0005073/miRNA-543/AKR1C1 axis to analyze AAA., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.)

Aortic aneurysm is a life-threatening disease with limited interventions that is closely related to vascular smooth muscle cell (VSMC) phenotypic switching. SLC44A2, a member of the solute carrier series 44 (SLC44) family, remains undercharacterized in the context of cardiovascular diseases. Venn diagram analysis based on microarray and single-cell RNA sequencing identified SLC44A2 as a major regulator of VSMC phenotypic switching in aortic aneurysm. Screening for Slc44a2 among aortic cell lineages demonstrated its predominant location in VSMCs. Elevated levels of SLC44A2 were evident in the aorta of both patients with abdominal aortic aneurysm and angiotensin II-infused (Ang II-infused) Apoe-/- mice. In vitro, SLC44A2 silencing promoted VSMCs toward a synthetic phenotype, while SLC44A2 overexpression attenuated VSMC phenotypic switching. VSMC-specific SLC44A2-knockout mice were more susceptible to aortic aneurysm under Ang II infusion, while SLC44A2 overexpression showed protective effects. Mechanistically, SLC44A2's interaction with NRP1 and ITGB3 activates TGF-β/SMAD signaling, thereby promoting contractile gene expression. Elevated SLC44A2 in aortic aneurysm is associated with upregulated runt-related transcription factor 1 (RUNX1). Furthermore, low-dose lenalidomide (LEN; 20 mg/kg/day) suppressed aortic aneurysm progression by enhancing SLC44A2 expression. These findings reveal that the SLC44A2-NRP1-ITGB3 complex is a major regulator of VSMC phenotypic switching and provide a potential therapeutic approach (LEN) for aortic aneurysm treatment.

Abdominal aortic aneurysm (AAA) is a life-threatening disease that remains undetected until it acutely ruptures. Due to lack of effective pharmaceutic therapies, it is urgent to explore new prevention and treatment strategies. Metabolic reprogramming is a cellular process through which cells change their metabolic patterns to meet material and energy requirements, including glucose metabolism, lipid metabolism and amino acid metabolism. Recently, the regulatory role of metabolic reprogramming in cardiovascular diseases, especially AAA, has attracted significant attention. This review article focuses on the research progress regarding the effects of metabolic reprogramming of vascular smooth muscle cells (VSMCs) and macrophages on the occurrence and development of AAA, especially their roles in major pathological processes such as VSMCs apoptosis and phenotype transformation, extracellular matrix remodeling, oxidative stress, and inflammatory response. The aim is to provide new clues for the mechanism research and clinical treatment of AAA from the perspective of metabolism.

Abdominal aortic aneurysm (AAA) is a chronic aortic disease that lacks effective pharmacological therapies. This study was performed to determine the influence of treatment with the gasdermin D inhibitor necrosulfonamide on experimental AAAs. AAAs were induced in male apolipoprotein E-deficient mice by subcutaneous angiotensin II infusion (1000 ng/kg body weight/min), with daily administration of necrosulfonamide (5 mg/kg body weight) or vehicle starting 3 days prior to angiotensin II infusion for 30 days. Necrosulfonamide treatment remarkably suppressed AAA enlargement, as indicated by reduced suprarenal maximal external diameter and surface area, and lowered the incidence and reduced the severity of experimental AAAs. Histologically, necrosulfonamide treatment attenuated medial elastin breaks, smooth muscle cell depletion, and aortic wall collagen deposition. Macrophages, CD4 + T cells, CD8 + T cells, and neovessels were reduced in the aneurysmal aortas of necrosulfonamide- as compared to vehicle-treated angiotensin II-infused mice. Atherosclerosis and intimal macrophages were also substantially reduced in suprarenal aortas from angiotensin II-infused mice following necrosulfonamide treatment. Additionally, the levels of serum interleukin-1β and interleukin-18 were significantly lower in necrosulfonamide- than in vehicle-treated mice without affecting body weight gain, lipid levels, or blood pressure. Our findings indicate that necrosulfonamide reduced experimental AAAs by preserving aortic structural integrity as well as reducing mural leukocyte accumulation, neovessel formation, and systemic levels of interleukin-1β and interleukin-18. Thus, pharmacologically inhibiting gasdermin D activity may lead to the establishment of nonsurgical therapies for clinical AAA disease.

Abdominal aortic aneurysm (AAA) is a progressive dilatation of the aorta that can lead to aortic rupture. The pathophysiology of the disease is not well characterized but is known to be caused by the general breakdown of the extracellular matrix within the aortic wall. In this comprehensive literature review, all current research on proteins that have been investigated for their potential prognostic capabilities in patients with AAA was included. A total of 45 proteins were found to be potential prognostic biomarkers for AAA, predicting incidence of AAA, AAA rupture, AAA growth, endoleak, and post-surgical mortality. The 45 proteins fell into the following seven general categories based on their primary function: (1) cardiovascular health, (2) hemostasis, (3) transport proteins, (4) inflammation and immunity, (5) kidney function, (6) cellular structure, (7) and hormones and growth factors. This is the most up-to-date literature review on current prognostic markers for AAA and their functions. This review outlines the wide pathophysiological processes that are implicated in AAA disease progression.

Abdominal aortic aneurysm (AAA) is a vascular disease characterized by progressive dilation of the abdominal aorta. Previous studies have suggested that dietary components are closely associated with AAA. Among those dietary components, eicosapentaenoic acid (EPA) is considered to have suppressive effects on AAA. In the AAA wall of AAA model animals bred under EPA-rich condition, the distribution of EPA-containing phosphatidylcholine (EPA-PC) has been reported to be similar to that of the markers of mesenchymal stem cells (MSCs) and M2 macrophages. These data suggest that the suppressive effects of EPA on AAA are related to preferential distribution of specific cells in the aortic wall. However, the distribution of EPA-PC in the AAA wall of AAA model animals fed a diet containing small amounts of EPA, which has not been reported to inhibit AAA, has not yet been explored. In the present study, we visualized the distribution of EPA-PCs in the AAA wall of AAA model animals fed a diet containing small amounts of EPA (1.5% EPA in the fatty acid composition) to elucidate the vasoprotective effects of EPA. Positive areas for markers of MSCs were significantly higher in the region where EPA-PC was abundant compared to the regions where EPA-PC was weakly detected, but not for markers of M2 macrophages, matrix metalloproteinase (MMP)-2, and MMP-9. The distribution of MSC markers was similar to that of EPA-PC but not that of M2 macrophages and MMPs. These data suggest preferential incorporation of EPA into MSCs under the conditions used in this study. The incorporation of EPA into certain cells may differ according to dietary conditions, which affect the development of AAA.

Competing Interests: Disclosures A. Daugherty is a consultant for Regeneron. S.M. Damrauer receives research support to his institution from RenalytixAI and in-kind support from Novo Nordisk outside the scope of the current work. The other authors report no conflicts.

Background: Pentamethylquercetin (PMQ) is a natural polymethyl flavonoid that possesses anti-apoptotic and other biological properties. Abdominal aortic aneurysm (AAA), a fatal vascular disease with a high risk of rupture, is associated with phenotypic switching and apoptosis of medial vascular smooth muscle cells (VSMCs). This study aimed to investigate the protective effects of PMQ on the development of AAA and the underlying mechanism., Methods: ApoE -/- mice were continuously infused with angiotensin II (Ang II) for 4 weeks to develop the AAA model. Intragastric administration of PMQ was initiated 5 days before Ang II infusion and continued for 4 weeks. In vitro, VSMCs were cultured and pretreated with PMQ, stimulated with Ang II. Real-time PCR, western blotting, and immunofluorescence staining were used to examine the roles and mechanisms of PMQ on the phenotypic switching and apoptosis of VSMCs., Results: PMQ dose-dependently reduced the incidence of Ang II-induced AAA, aneurysm diameter enlargement, elastin degradation, VSMCs phenotypic switching and apoptosis. Furthermore, PMQ also inhibited phenotypic switching and apoptosis in Ang II-stimulated VSMCs. PMQ exerted protective effects by regulating the C/EBPβ/PTEN/AKT/GSK-3β axis. AAV-mediated overexpression of PTEN reduced the therapeutic effects of PMQ in the AAA model mice, suggesting that the effects of PMQ on Ang II-mediated AAA formation were related to the PTEN/AKT/GSK-3β axis. PMQ inhibited VSMCs phenotypic switching and apoptosis by bounding to C/EBPβ at Lys253 with hydrogen bond to regulate C/EBPβ nuclear translocation and PTEN/AKT/GSK-3β axis, thereby inhibiting Ang II-induced AAA formation., Conclusions: Pentamethylquercetin inhibits angiotensin II-induced abdominal aortic aneurysm formation by bounding to C/EBPβ at Lys253. Therefore, PMQ prevents the formation of AAA and reduces the incidence of AAA., Competing Interests: Declaration of competing interest This manuscript has not been published or presented elsewhere in part or in entirety and is not under consideration by another journal. We have read and understood your journal's policies, and we believe that neither the manuscript nor the study violates any of these. All authors participated declared that they had no anything to disclose regarding funding or conflict of interest with respect to present study., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Abdominal aortic aneurysm (AAA) is a degenerative disease characterized by local abnormal dilation of the aorta accompanied by vascular smooth muscle cell (VSMC) dysfunction and chronic inflammation. VSMC dedifferentiation, transdifferentiation, and increased expression of matrix metalloproteinases (MMPs) are essential causes of AAA formation. Previous studies from us and others have shown that Anemoside B4 (AB4), a saponin from Pulsatilla chinensis , has anti-inflammatory, anti-tumor, and regulatory effects on VSMC dedifferentiation. The current study aimed to investigate whether AB4 inhibits AAA development and its underlying mechanisms. By using an Ang II induced AAA model in vivo and cholesterol loading mediated VSMC to macrophage transdifferentiation model in vitro , our study demonstrated that AB4 could attenuate AAA pathogenesis, prevent VSMC dedifferentiation and transdifferentiation to macrophage-like cells, decrease vascular inflammation, and suppress MMP expression and activity. Furthermore, KLF4 overexpression attenuated the effects of AB4 on VSMC to macrophage-like cell transition and VSMC inflammation in vitro . In conclusion, AB4 protects against AAA formation in mice by inhibiting KLF4 mediated VSMC transdifferentiation and inflammation. Our study provides the first proof of concept of using AB4 for AAA management., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Chu, Shan, He, Yang, Feng, Zhang and Yu.)

Human abdominal aortic aneurysms (AAAs) are characterized by increased activity of matrix metalloproteinases (MMP), including MMP-12, alongside macrophage accumulation and elastin degradation, in conjunction with superimposed atherosclerosis. Previous genetic ablation studies have proposed contradictory roles for MMP-12 in AAA development. In this study, we aimed to elucidate if pharmacological inhibition of MMP-12 activity with a phosphinic peptide inhibitor protects from AAA formation and progression in angiotensin (Ang) II-infused Apoe -/- mice. Complimentary studies were conducted in a human ex vivo model of early aneurysm development. Administration of an MMP-12 inhibitor (RXP470.1) protected hypercholesterolemia Apoe -/- mice from Ang II-induced AAA formation and rupture-related death, associated with diminished medial thinning and elastin fragmentation alongside increased collagen deposition. Proteomic analyses confirmed a beneficial effect of MMP-12 inhibition on extracellular matrix remodeling proteins combined with inflammatory pathways. Furthermore, RXP470.1 treatment of mice with pre-existing AAAs exerted beneficial effects as observed through suppressed aortic dilation and rupture, medial thinning, and elastin destruction. Our findings indicate that pharmacological inhibition of MMP-12 activity retards AAA progression and improves survival in mice providing proof-of-concept evidence to motivate translational work for MMP-12 inhibitor therapy in humans.

Background: Abdominal aortic aneurysm (AAA) is a catastrophic disease with little effective therapy, likely due to the limited understanding of the mechanisms underlying AAA development and progression. ATF3 (activating transcription factor 3) has been increasingly recognized as a key regulator of cardiovascular diseases. However, the role of ATF3 in AAA development and progression remains elusive., Methods: Genome-wide RNA sequencing analysis was performed on the aorta isolated from saline or Ang II (angiotensin II)-induced AAA mice, and ATF3 was identified as the potential key gene for AAA development. To examine the role of ATF3 in AAA development, vascular smooth muscle cell-specific ATF3 knockdown or overexpressed mice by recombinant adeno-associated virus serotype 9 vectors carrying ATF3, or shRNA-ATF3 with SM22α (smooth muscle protein 22-α) promoter were used in Ang II-induced AAA mice. In human and murine vascular smooth muscle cells, gain or loss of function experiments were performed to investigate the role of ATF3 in vascular smooth muscle cell proliferation and apoptosis., Results: In both Ang II-induced AAA mice and patients with AAA, the expression of ATF3 was reduced in aneurysm tissues but increased in aortic lesion tissues. The deficiency of ATF3 in vascular smooth muscle cell promoted AAA formation in Ang II-induced AAA mice. PDGFRB (platelet-derived growth factor receptor β) was identified as the target of ATF3, which mediated vascular smooth muscle cell proliferation in response to TNF-alpha (tumor necrosis factor-α) at the early stage of AAA. ATF3 suppressed the mitochondria-dependent apoptosis at the advanced stage by upregulating its direct target BCL2. Our chromatin immunoprecipitation results also demonstrated that the recruitment of NFκB1 and P300/BAF/H3K27ac complex to the ATF3 promoter induces ATF3 transcription via enhancer activation. NFKB1 inhibitor (andrographolide) inhibits the expression of ATF3 by blocking the recruiters NFKB1 and ATF3-enhancer to the ATF3-promoter region, ultimately leading to AAA development., Conclusions: Our results demonstrate a previously unrecognized role of ATF3 in AAA development and progression, and ATF3 may serve as a novel therapeutic and prognostic marker for AAA., Competing Interests: Disclosures None.

Glutamine (Gln), known as the most abundant free amino acid, is widely spread in human body. In this study, we demonstrated the protective effects of glutamine against mouse abdominal aortic aneurysm (AAA) induced by both angiotensin II (AngII) and calcium phosphate (Ca 3 (PO 4 ) 2 ) in vivo , which was characterized with lower incidence of mouse AAA. Moreover, histomorphological staining visually presented more intact elastic fiber and less collagen deposition in abdominal aortas of mice treated by glutamine. Further, we found glutamine inhibited the excessive production of reactive oxide species (ROS), activity of matrix metalloproteinase (MMP), M1 macrophage activation, and apoptosis of vascular smooth muscle cells (VSMCs) in suprarenal abdominal aortas of mice, what's more, the high expressions of MMP-2 protein, MMP-9 protein, pro-apoptotic proteins, and IL-6 as well as TNF-α in protein and mRNA levels in cells treated by AngII were down-regulated by glutamine. Collectively, these results revealed that glutamine protected against mouse AAA through inhibiting apoptosis of VSMCs, M1 macrophage activation, oxidative stress, and extracellular matrix degradation., Competing Interests: Competing Interests: The authors have declared that no competing interest exists., (© The author(s).)

Abdominal aortic aneurysm (AAA) has been recognized as a serious chronic inflammatory degenerative aortic disease in recent years. At present, there is no other effective intervention except surgical treatment for AAA. With the aging of the human population, its incidence is increasing year by year, posing a serious threat to human health. Modern studies suggest that vascular chronic inflammatory response is the core process in AAA occurrence and development. Inflammasome, a multiprotein complex located in the cytoplasm, mediates the expression of various inflammatory cytokines like interleukin (IL)-1β and IL-18, and thus plays a pivotal role in inflammation regulation. Therefore, inflammasome may exert a crucial influence on the progression of AAA. This article reviews some mechanism studies to investigate the role of inflammasome in AAA and then summarizes several potential drugs targeting inflammasome for the treatment of AAA, aiming to provide new ideas for the clinical prevention and treatment of AAA beyond surgical methods.

During resolution of inflammation, specialized proresolving mediators (SPMs), including resolvins, are produced to restore tissue homeostasis. We hypothesized that there might be a dysregulation of SPMs pathways in pathological vascular remodeling and that resolvin D2 (RvD2) might prevent vascular remodeling and contractile and endothelial dysfunction in a model of obesity and hypertension. In aortic samples of patients with or without abdominal aortic aneurysms (AAA), we evaluated gene expression of enzymes involved in SPMs synthesis (ALOXs), SPMs receptors and pro-inflammatory genes. In an experimental model of aortic dilation induced by high fat diet (HFD, 60%, eighteen weeks) and angiotensin II (AngII) infusion (four weeks), we studied the effect of RvD2 administration in aorta and small mesenteric arteries structure and function and markers of inflammation. In human macrophages we evaluated the effects of AngII and RvD2 in macrophages function and SPMs profile. In patients, we found positive correlations between AAA and obesity, and between AAA and expression of ALOX15, RvD2 receptor GPR18, and pro-inflammatory genes. There was an inverse correlation between the expression of aortic ALOX15 and AAA growth rate. In the mice model, RvD2 partially prevented the HFD plus AngII-induced obesity and adipose tissue inflammation, hypertension, aortic and mesenteric arteries remodeling, hypercontratility and endothelial dysfunction, and the expression of vascular proinflammatory markers and cell apoptosis. In human macrophages, RvD2 prevented AngII-induced impaired efferocytosis and switched SPMs profile. RvD2 might represent a novel protective strategy in preventing vascular damage associated to hypertension and obesity likely through effects in vascular and immune cells., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Background and Aims: In this study, we carried out a clinical sample study, and in vivo and in vitro studies to evaluate the effect of SIRT6 and SIRT6-mediated vascular smooth muscle senescence on the development of abdominal aortic aneurysm (AAA)., Method and Results: AAA specimen showed an increased P16, P21 level and a decreased SIRT6 level compared with control aorta. Time curve study of Ang II infusion AAA model showed similar P16, P21 and SIRT6 changes at the early phase of AAA induction. The in vivo overexpression of SIRT6 significantly prevented AAA formation in Ang II infusion model. The expression of P16 and P21 was significantly reduced after SIRT6 overexpression. SIRT6 overexpression also attenuated chronic inflammation and neo-angiogenesis in Ang II infusion model. The overexpression of SIRT6 could attenuate premature senescence, inflammatory response and neo-angiogenesis in human aortic smooth muscle cells (HASMC) under Ang II stimulation., Conclusions: SIRT6 overexpression could limit AAA formation via attenuation of vascular smooth muscle senescence, chronic inflammation and neovascularity., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

An abdominal aortic aneurysm (AAA) is a life-threatening cardiovascular disease. We identified plasma insulin-like growth factor 1 (IGF1) as an independent risk factor in patients with AAA by correlating plasma IGF1 with risk. Smooth muscle cell- or fibroblast-specific knockout of Igf1r , the gene encoding the IGF1 receptor (IGF1R), attenuated AAA formation in two mouse models of AAA induced by angiotensin II infusion or CaCl 2 treatment. IGF1R was activated in aortic aneurysm samples from human patients and mice with AAA. Systemic administration of IGF1C, a peptide fragment of IGF1, 2 weeks after disease development inhibited AAA progression in mice. Decreased AAA formation was linked to competitive inhibition of IGF1 binding to its receptor by IGF1C and modulation of downstream alpha serine/threonine protein kinase (AKT)/mammalian target of rapamycin signaling. Localized application of an IGF1C-loaded hydrogel was developed to reduce the side effects observed after systemic administration of IGF1C or IGF1R antagonists in the CaCl 2 -induced AAA mouse model. The inhibitory effect of the IGF1C-loaded hydrogel administered at disease onset on AAA formation was further evaluated in a guinea pig-to-rat xenograft model and in a sheep-to-minipig xenograft model of AAA formation. The therapeutic efficacy of IGF1C for treating AAA was tested through extravascular delivery in the sheep-to-minipig model with AAA established for 2 weeks. Percutaneous injection of the IGF1C-loaded hydrogel around the AAA resulted in improved vessel flow dynamics in the minipig aorta. These findings suggest that extravascular administration of IGF1R antagonists may have translational potential for treating AAA.

Introduction: Cyclic nucleotide phosphodiesterases (PDEs) of the PDE4 subfamily are responsible for the hydrolysis and subcellular compartmentalization of cAMP, a second messenger that modulates vascular functionality. We had shown that PDE4B is induced in abdominal aortic aneurysms (AAA) and that PDE4 inhibition by rolipram limits experimental aneurysms. In this study we have delved into the mechanisms underlying the beneficial effect of rolipram on AAA., Methods: AAA were induced in ApoE -/- mice by angiotensin II (Ang II) infusion. Aneurysm formation was evaluated by ultrasonography. The expression of enzymes involved in rédox homeostasis was analyzed by real-time RT-PCR and the activation of signaling pathways by Western blot., Results: Induction of PDE4B in human AAA has been confirmed in a second cohort of patients. In Ang II-infused ApoE -/- mice, rolipram increased the percentage of animals free of aneurysms without affecting the percentage of aortic ruptures. Quantitative analyses determined that this drug significantly attenuated aortic collagen deposition. Additionally, rolipram reduced the increased Nox2 expression triggered by Ang II, exacerbated Sod1 induction, and normalized Sod3 expression. Likewise, PDE4 inhibition decreased the activation of both ERK1/2 and the canonical Wnt pathway, while AKT activity was not altered., Conclusions: The inhibition of PDE4 activity modulates the expression of enzymes involved in rédox homeostasis and affects cell signaling pathways involved in the development of AAA., (Copyright © 2023 Sociedad Española de Arteriosclerosis. Publicado por Elsevier España, S.L.U. All rights reserved.)

Background: Abdominal aortic aneurysm is a weakening and expansion of the abdominal aorta. Currently, there is no drug treatment to limit abdominal aortic aneurysm growth. The glycocalyx is the outermost layer of the cell surface, mainly composed of glycosaminoglycans and proteoglycans., Objective: The aim of this review was to identify a potential relationship between glycocalyx disruption and abdominal aortic aneurysm pathogenesis., Methods: A narrative review of relevant published research was conducted., Results: Glycocalyx disruption has been reported to enhance vascular permeability, impair immune responses, dysregulate endothelial function, promote extracellular matrix remodeling and modulate mechanotransduction. All these effects are implicated in abdominal aortic aneurysm pathogenesis. Glycocalyx disruption promotes inflammation through exposure of adhesion molecules and release of proinflammatory mediators. Glycocalyx disruption affects how the endothelium responds to shear stress by reducing nitric oxide availabilty and adversely affecting the storage and release of several antioxidants, growth factors, and antithromotic proteins. These changes exacerbate oxidative stress, stimulate vascular smooth muscle cell dysfunction, and promote thrombosis, all effects implicated in abdominal aortic aneurysm pathogenesis. Deficiency of key component of the glycocalyx, such as syndecan-4, were reported to promote aneurysm formation and rupture in the angiotensin-II and calcium chloride induced mouse models of abdominal aortic aneurysm., Conclusion: This review provides a summary of past research which suggests that glycocalyx disruption may play a role in abdominal aortic aneurysm pathogenesis. Further research is needed to establish a causal link between glycocalyx disruption and abdominal aortic aneurysm development., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this study., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Aims: Abdominal aortic aneurysm (AAA) is a highly lethal disease with progressive dilatation of the abdominal aorta accompanied by degradation and remodelling of the vessel wall due to chronic inflammation. Platelets play an important role in cardiovascular diseases, but their role in AAA is poorly understood., Methods and Results: The present study revealed that platelets play a crucial role in promoting AAA through modulation of inflammation and degradation of the extracellular matrix (ECM). They are responsible for the up-regulation of SPP1 (osteopontin, OPN) gene expression in macrophages and aortic tissue, which triggers inflammation and remodelling and also platelet adhesion and migration into the abdominal aortic wall and the intraluminal thrombus (ILT). Further, enhanced platelet activation and pro-coagulant activity result in elevated gene expression of various cytokines, Mmp9 and Col1a1 in macrophages and Il-6 and Mmp9 in fibroblasts. Enhanced platelet activation and pro-coagulant activity were also detected in AAA patients. Further, we detected platelets and OPN in the vessel wall and in the ILT of patients who underwent open repair of AAA. Platelet depletion in experimental murine AAA reduced inflammation and ECM remodelling, with reduced elastin fragmentation and aortic diameter expansion. Of note, OPN co-localized with platelets, suggesting a potential role of OPN for the recruitment of platelets into the ILT and the aortic wall., Conclusion: In conclusion, our data strongly support the potential relevance of anti-platelet therapy to reduce AAA progression and rupture in AAA patients., Competing Interests: Conflict of interest: None declared., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Abdominal aortic aneurysm (AAA) is a deadly, permanent ballooning of the aortic artery. Pharmacological and genetic studies have pointed to multiple proteins, including microsomal prostaglandin E 2 synthase-1 (mPGES-1), as potentially promising targets. However, it remains unknown whether administration of an mPGES-1 inhibitor can effectively attenuate AAA progression in animal models. There are still no FDA-approved pharmacological treatments for AAA. Current research stresses the importance of both anti-inflammatory drug targets and rigor of translatability. Notably, mPGES-1 is an inducible enzyme responsible for overproduction of prostaglandin E 2 (PGE 2 )-a well-known principal pro-inflammatory prostanoid. Here we demonstrate for the first time that a highly selective mPGES-1 inhibitor (UK4b) can completely block further growth of AAA in the ApoE-/- angiotensin (Ang)II mouse model. Our findings show promise for the use of a mPGES-1 inhibitor like UK4b as interventional treatment of AAA and its potential translation into the clinical setting., (© 2024. The Author(s).)

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., Competing Interests: Disclosures None.

Abdominal aortic aneurysm (AAA) is a fatal cardiovascular disorder with high mortality and morbidity rates. To date, no drug has shown to significantly alleviate the risk of AAA. Previous studies have indicated that hyperhomocysteinemia (HHcy) significantly increases the incidence of AAA by disrupting endothelial cell homeostasis; however, the potential molecular mechanisms require clarification. Herein, we aimed to integrate transcriptomics analysis and molecular biology experiments to explore the potential molecular targets by which HHcy may increase the incidence of AAA. We integrated two AAA data profiles (GSE57691 and GSE7084) based on previously published microarray ribonucleic acid sequencing (RNAseq) data from the GEO database. Additionally, 500 μM homocysteine-treated human aorta endothelium cells microarray dataset (GSE175748) was downloaded and processed. Subsequently, single-cell RNA-seq profiles of the aortic aneurysms (GSE155468) were downloaded, scaled, and processed for further analysis. The microarray profiles analysis demonstrated that the Ras association domain family member 2 (RASSF2) and interleukin (IL)-1β are potentially the target genes involved in the HHcy-mediated aggravation of AAA formation. Single-cell RNAseq analysis revealed that RASSF2 might impair endothelial cell function by increasing inflammatory cell infiltration to participate in AAA formation. Finally, we conducted reverse transcription quantitative polymerase chain reaction and immunofluorescence analysis to validate the up-regulated mRNA expression of RASSF2 (p = 0.008) and IL-1β (p = 0.002) in AAA tissue compared to control tissue. Immunofluorescence staining revealed overexpression of RASSF2 protein in AAA tissue sections compared to control tissue (p = 0.037). Co-localization of RASSF2 and the aortic endothelium cell marker, CD31, was observed in tissue sections, indicating the potential involvement of RASSF2 in aortic endothelial cells. To summarise, our preliminary study revealed that HHcy may worsen AAA formation by up-regulating the expression of RASSF2 and IL-1β in aortic endothelium cells., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)