Age-Disturbed Vascular Extracellular Matrix Links to Abdominal Aortic Aneurysms.

Abdominal aortic aneurysm (AAA) is a common but life-threatening vascular condition in men at an advanced age. However, the underlying mechanisms of age-increased incidence and mortality of AAA remain elusive. Here, we performed RNA sequencing (RNA-seq) of mouse aortas from males (young: 3-month, n = 4 vs old: 23-month, n = 4) and integrated with the data sets of human aortas (young: 20-39, n = 47 vs old: 60-79 years, n = 92) from GTEx project and the data set (GSE183464) for AAA to search for age-shifted aortic aneurysm genes, their relevant biological processes, and signaling pathways. Angiotensin II-induced AAA in mice was used to verify the critical findings. We found 1 001 genes transcriptionally changed with ages in both mouse and human. Most age-increased genes were enriched intracellularly and the relevant biological processes included mitochondrial function and translational controls, whereas the age-decreased genes were largely localized in extracellular regions and cell periphery and the involved biological processes were associated with extracellular matrix (ECM). Fifty-one were known genes for AAA and found dominantly in extracellular region. The common age-shifted vascular genes and known aortic aneurysm genes had shared functional influences on ECM organization, apoptosis, and angiogenesis. Aorta with angiotensin II-induced AAA exhibited similar phenotypic changes in ECM to that in old mice. Together, we present a conserved transcriptional signature for aortic aging and provide evidence that mitochondrial dysfunction and the imbalanced ribosomal homeostasis act likely as driven-forces for aortic aging and age-disturbed ECM is the substrate for developing AAA.

Biogenesis of circRBM33 mediated by N6-methyladenosine and its function in abdominal aortic aneurysm.

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.

MS4A1-PTGS2 axis induces taurine metabolic reprogramming to exacerbate abdominal aortic aneurysm progression.

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.

Deciphering the causal association and underlying transcriptional mechanisms between telomere length and abdominal aortic aneurysm.

Background: The purpose of this study is to investigate the causal effect and potential mechanisms between telomere length and abdominal aortic aneurysm (AAA). Methods: Summary statistics of telomere length and AAA were derived from IEU open genome-wide association studies and FinnGen R9, respectively. Bi-directional Mendelian randomization (MR) analysis was conducted to reveal the causal relationship between AAA and telomere length. Three transcriptome datasets were retrieved from the Gene Expression Omnibus database and telomere related genes was down-loaded from TelNet. The overlapping genes of AAA related differentially expressed genes (DEGs), module genes, and telomere related genes were used for further investigation. Telomere related diagnostic biomarkers of AAA were selected with machine learning algorisms and validated in datasets and murine AAA model. The correlation between biomarkers and immune infiltration landscape was established. Results: Telomere length was found to have a suggestive negative associations with AAA [IVW, OR 95%CI = 0.558 (0.317-0.701), P < 0.0001], while AAA showed no suggestive effect on telomere length [IVW, OR 95%CI = 0.997 (0.990-1.004), P = 0.4061]. A total of 40 genes was considered as telomere related DEGs of AAA. PLCH2, PRKCQ, and SMG1 were selected as biomarkers after multiple algorithms and validation. Immune infiltration analysis and single cell mRNA analysis revealed that PLCH2 and PRKCQ were mainly expressed on T cells, while SMG1 predominantly expressed on T cells, B cells, and monocytes. Murine AAA model experiments further validated the elevated expression of biomarkers. Conclusion: We found a suggestive effect of telomere length on AAA and revealed the potential biomarkers and immune mechanism of telomere length on AAA. This may shed new light for diagnosis and therapeutics on AAA.

Evaluating the cost-effectiveness of polygenic risk score-stratified screening for abdominal aortic aneurysm.

As the heritability of abdominal aortic aneurysm (AAA) is high and AAA partially shares genetic architecture with other cardiovascular diseases, genetic information could help inform AAA screening strategies. Exploiting pleiotropy and meta-analysing summary data from large studies, we construct a polygenic risk score (PRS) for AAA. Leveraging related traits improves PRS performance (R2) by 22.7%, relative to using AAA alone. Compared with the low PRS tertile, intermediate and high tertiles have hazard ratios for AAA of 2.13 (95%CI 1.61, 2.82) and 3.70 (95%CI 2.86, 4.80) respectively, adjusted for clinical risk factors. Using simulation modelling, we compare PRS- and smoking-stratified screening with inviting men at age 65 and not inviting women (current UK strategy). In a futuristic scenario where genomic information is available, our modelling suggests inviting male current smokers with high PRS earlier than 65 and screening female smokers with high/intermediate PRS at 65 and 70 respectively, may improve cost-effectiveness.

Macrophage ILF3 promotes abdominal aortic aneurysm by inducing inflammatory imbalance in male mice.

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.

A nomoscore of four genes for predicting the rupture risk in abdominal aortic aneurysm patients with osteoarthritis.

BACKGROUND: Abdominal aortic aneurysm (AAA) represents one of the most life-threatening cardiovascular diseases and is increasingly becoming a significant global public health concern. The aneurysms-osteoarthritis syndrome (AOS) has gained recognition, as patients with this syndrome often exhibit early-stage osteoarthritis (OA) and have a substantially increased risk of rupture, even with mild dilation of the aneurysm. The aim of this study was to discover potential biomarkers that can predict the occurrence of AAA rupture in patients with OA. METHODS: Two gene expression profile datasets (GSE98278, GSE51588) and two single-cell RNA-seq datasets (GSE164678, GSE152583) were obtained from the GEO database. Functional enrichment analysis, PPI network construction, and machine learning algorithms, including LASSO, Random Forest, and SVM-RFE, were utilized to identify hub genes. In addition, a nomogram and ROC curves were generated to predict the risk of rupture in patients with AAA. Moreover, we analyzed the immune cell infiltration in the AAA tissue microenvironment by CIBERSORT and validated key gene expression in different macrophage subtypes through single-cell analysis. RESULTS: A total of 105 intersecting DEGs that showed consistent changes between rAAA and OA dataset were identified. From these DEGs, four hub genes (PAK1, FCGR1B, LOX and PDPN) were selected by machine learning. High predictive performance was observed for the nomogram based on these hub genes, with an AUC of 0.975 (95 % CI: 0.942-1.000). Abnormal immune cell infiltration was detected in rAAA and correlated significantly with the hub genes. Ruptured AAA cases exhibited higher nomoscore values and lower M2 macrophage infiltration compared to stable AAA. Validation in animal models (PPE+BAPN-induced rAAA) confirmed the significant role of these biomarkers in AAA pathology. CONCLUSION: The present study successfully identified four potential hub genes (PAK1, FCGR1B, LOX and PDPN) and developed a robust predictive nomogram to assess the risk of AAA rupture. The findings also shed light on the connection between hub genes and immune cell components in the microenvironment of rAAA. These findings support future research on key genes in AAA patients with OA, providing insights for novel management strategies for AAA.

Investigating the association between gut microbiome and aortic aneurysm diseases: a bidirectional two-sample Mendelian randomization analysis.

Objective: This study aims to investigate the associations between specific bacterial taxa of the gut microbiome and the development of aortic aneurysm diseases, utilizing Mendelian Randomization (MR) to explore these associations and overcome the confounding factors commonly present in observational studies. Methods: Employing the largest available gut microbiome and aortic aneurysm Genome-Wide Association Study databases, including MiBioGen, Dutch Microbiome Project, FinnGen, UK Biobank, and Michigan Genomics Initiative, this study performs two-sample bidirectional MR analyses. Instrumental variables, linked to microbiome taxa at significant levels, were selected for identifying relationships with abdominal aortic aneurysms (AAA), thoracic aortic aneurysms (TAA), and aortic dissection (AD). Methods like inverse variance weighted, MR-PRESSO, MR-Egger, weighted median, simple mode, and mode-based estimate were used for MR analysis. Heterogeneity was assessed with the Cochran Q test. MR-Egger regression and MR-PRESSO addressed potential unbalanced horizontal pleiotropy. Results: The analysis did not find any evidence of statistically significant associations between the gut microbiome and aortic aneurysm diseases after adjusting for the false discovery rate (FDR). Specifically, while initial results suggested correlations between 19 taxa and AAA, 25 taxa and TAA, and 13 taxa with AD, these suggested associations did not hold statistical significance post-FDR correction. Therefore, the role of individual gut microbial taxa as independent factors in the development and progression of aortic aneurysm diseases remains inconclusive. This finding underscores the necessity for larger sample sizes and more comprehensive studies to further investigate these potential links. Conclusion: The study emphasizes the complex relationship between the gut microbiome and aortic aneurysm diseases. Although no statistically significant associations were found after FDR correction, the findings provide valuable insights and highlight the importance of considering gut microbiota in aortic aneurysm diseases research. Understanding these interactions may eventually contribute to identifying new therapeutic and preventive strategies for aortic aneurysm diseases.

Integrative analysis of single-Cell RNA sequencing and experimental validation in the study of abdominal aortic aneurysm progression.

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.

Causal relationship between gut microbiota, plasma metabolites, inflammatory cytokines and abdominal aortic aneurysm: a Mendelian randomization study.

BACKGROUND: Complex interconnections are evident among gut microbiota, circulating metabolites, inflammatory cytokines, and the pathogenesis of abdominal aortic aneurysms (AAA), with the causal dynamics yet to be comprehensively elucidated. The primary objective of this study was to elucidate the potential causal relationships involving gut microbiota-mediated plasma metabolites, inflammatory cytokines, and AAA. METHODS: We utilized data from genome-wide association studies predominantly comprising individuals of European ancestry, encompassing four major gut microbiota signatures, 233 plasma metabolite signatures (N = 136,016), 91 inflammatory cytokine signatures (N = 14,824), and AAA signatures (N = 1,458,875). Mendelian randomization (MR), employed in a two-sample format, was utilized as a tool to investigate the potential causal pathways from gut microbiota to the development of AAA. Additionally, a two-step MR approach was employed to dissect the impact of plasma metabolites and inflammatory cytokines on the relationship between gut microbiota and AAA and to ascertain the mediated fractions. RESULTS: Our findings indicate that five phylum or family-identical bacteria, 175 plasma metabolites, and seven inflammatory factors are causally associated with AAA. Among them, five bacterial species from the same phylum or family, identified from different GWAS data, were strongly associated with AAA. Of these, two exhibited negative causality and three exhibited positive causality. We found that the phylum Firmicutes and the families Oscillospiraceae might reduce the risk of AAA, whereas the families Prevotellaceae, Sutterellaceae, and Aminobacteriaceae might increase the risk of AAA. Further screening indicated that phylum Firmicutes id.1672 (GCST90017114) may confer a protective effect against AAA by reducing triglyceride levels in medium/small high-density lipoprotein (HDL). CONCLUSION: MR analysis has delineated a causal pathway from gut microbiota, through plasma circulating metabolites and inflammatory cytokines, to the pathogenesis of AAA. The role of intestinal flora and certain biomarkers may provide a reference for the diagnosis of AAA, and contribute to the prevention, diagnosis, and treatment of AAA disease.

Proprotein convertase subtilisin/kexin type 9 as a drug target for abdominal aortic aneurysm.

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.

Single-Cell RNA Sequencing Deconstructs the Distribution of Immune Cells Within Abdominal Aortic Aneurysms in Mice.

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.

Single-cell RNA sequencing reveals that NRF2 regulates vascular smooth muscle cell phenotypic switching in abdominal aortic aneurysm.

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.

Circulating inflammatory proteins and abdominal aortic aneurysm: A two-sample Mendelian randomization and colocalization analyses.

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.

L-Wnk1 Deletion in Smooth Muscle Cells Causes Aortitis and Inflammatory Shift.

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, Ly6Chi monocytes, and γδ T cells. Sm22Cre+Wnk1lox/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+Wnk1lox/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-ß (transforming growth factor-beta) 1 expression. Finally, in vivo TGF-ß blockade using neutralizing anti-TGF-ß antibody promoted saccular aneurysm formation and aorta rupture in Sm22 Cre+ Wnk1lox/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.

Abdominal aortic aneurysm and cardiometabolic traits share strong genetic susceptibility to lipid metabolism and inflammation.

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.

Single-cell RNA sequencing identifies interferon-inducible monocytes/macrophages as a cellular target for mitigating the progression of abdominal aortic aneurysm and rupture risk.

AIMS: Abdominal aortic aneurysm (AAA) represents a life-threatening condition characterized by medial layer degeneration of the abdominal aorta. Nevertheless, knowledge regarding changes in regulators associated with aortic status remains incomplete. A thorough understanding of cell types and signalling pathways involved in the development and progression of AAAs is essential for the development of medical therapy. METHODS AND RESULTS: We harvested specimens of the abdominal aorta with different pathological features in Angiotensin II (AngII)-infused ApoE-/- mice, conducted scRNA-seq, and identified a unique population of interferon-inducible monocytes/macrophages (IFNICs), which were amply found in the AAAs. Gene set variation analysis revealed that activation of the cytosolic DNA sensing cGAS-STING and JAK-STAT pathways promoted the secretion of type I interferons in monocytes/macrophages and differentiated them into IFNICs. We generated myeloid cell-specific deletion of Sting1 (Lyz2-Cre+/-; Sting1flox/flox) mice and performed bone marrow transplantation and found that myeloid cell-specific deletion of Sting1 or Ifnar1 significantly reduced the incidence of AAA, aortic rupture rate, and diameter of the abdominal aorta. Mechanistically, the activated pyroptosis- and inflammation-related signalling pathways, regulated by IRF7 in IFNICs, play critical roles in the developing AAAs. CONCLUSION: IFNICs are a unique monocyte/macrophage subset implicated in the development of AAAs and aortic rupture.

Construction of the circRNA-miRNA-mRNA axis based on ferroptosis-related gene AKR1C1 to explore the potential pathogenesis of abdominal aortic aneurysm.

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_circ_0005073-miRNA-543 and AKR1C1-miRNA-543 were identified by Online Database analysis. Therefore, we have established the has_circ_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_circ_0005073/miRNA-543/AKR1C1 axis to analyze AAA.

NINJ1 Facilitates Abdominal Aortic Aneurysm Formation via Blocking TLR4-ANXA2 Interaction and Enhancing Macrophage Infiltration.

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, Ninj1flox/flox and Ninj1flox/floxLyz2-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.