Monocytes and macrophages in abdominal aortic aneurysm

Intense impact of IL-1β expressing inflammatory macrophages in acute aortic dissection

There is no treatment for acute aortic dissection (AAD) targeting inflammatory cells. We aimed to identify the new therapeutic targets associated with inflammatory cells. We characterized the specific distribution of myeloid cells of both human type A AAD samples and a murine AAD model generated using angiotensin II (ANGII) and β-aminopropionitrile (BAPN) by single-cell RNA sequencing (scRNA-seq). We also examined the effect of an anti-interleukin-1β (IL-1β) antibody in the murine AAD model. IL1B+ inflammatory macrophages and classical monocytes were increased in human AAD samples. Trajectory analysis demonstrated that IL1B+ inflammatory macrophages differentiated from S100A8/9/12+ classical monocytes uniquely observed in the aorta of AAD. We found increased infiltration of neutrophils and monocytes with the expression of inflammatory cytokines in the aorta and accumulation of inflammatory macrophages before the onset of macroscopic AAD in the murine AAD model. In blocking experiments using an anti-IL-1β antibody, it improved survival of murine AAD model by preventing elastin degradation. We observed the accumulation of inflammatory macrophages expressing IL-1β in both human AAD samples and in a murine AAD model. Anti-IL-1β antibody could improve the mortality rate in mice, suggesting that it may be a treatment option for AAD.

A Dual-Targeting, Multi-Faceted Biocompatible Nanodrug Optimizes the Microenvironment to Ameliorate Abdominal Aortic Aneurysm

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.

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.

Innovation in pathogenesis and management of aortic aneurysm

Aortic aneurysm (AA) refers to the persistent dilatation of the aorta, exceeding three centimeters. Investigating the pathophysiology of this condition is important for its prevention and management, given its responsibility for more than 25000 deaths in the United States. AAs are classified based on their location or morphology. various pathophysiologic pathways including inflammation, the immune system and atherosclerosis have been implicated in its development. Inflammatory markers such as transforming growth factor β, interleukin-1β, tumor necrosis factor-α, matrix metalloproteinase-2 and many more may contribute to this phenomenon. Several genetic disorders such as Marfan syndrome, Ehler-Danlos syndrome and Loeys-Dietz syndrome have also been associated with this disease. Recent years has seen the investigation of novel management of AA, exploring the implication of different immune suppressors, the role of radiation in shrinkage and prevention, as well as minimally invasive and newly hypothesized surgical methods. In this narrative review, we aim to present the new contributing factors involved in pathophysiology of AA. We also highlighted the novel management methods that have demonstrated promising benefits in clinical outcomes of the AA.

Myeloid Cell mPGES-1 Deletion Attenuates Calcium Phosphate-induced Abdominal Aortic Aneurysm in Male Mice

Microsomal PGE2 synthase (mPGES)-1 is the key enzyme responsible for synthesizing inflammatory prostaglandin E2 (PGE2). Our previous studies have shown that deletion mPGES-1 in myeloid cells hinders atherogenesis, suppresses vascular proliferative response to injury and enhances survival after myocardial infarction. Here we aimed to further explore the influence of myeloid cell mPGES-1 deletion in abdominal aortic aneurysm (AAA) formation. The AAA was triggered by applying 0.5 M calcium phosphate (CaPO4) to the infrarenal aorta of both myeloid mPGES-1 knockout (Mac-mPGES-1-KO) and their littermate control Mac-mPGES-1-WT mice. AAA induction was assessed by calculating the expansion of the infrarenal aortic diameter 4 weeks after CaPO4 application. The maximum diameters of the aortas were measured by morphometry and the mean maximal diameters were calculated. Paraffin sections of the infrarenal aortas were examined for morphological analysis and immunohistochemical staining. The results showed that myeloid cell mPGES-1 deletion significantly mitigated AAA formation, including reducing expansion of the infrarenal aorta, preventing elastic lamellar degradation, and decreasing aortic calcium deposition. Immunohistochemical staining further indicated that macrophage infiltration and matrix metalloproteinase 2 (MMP2) expression was attenuated in the Mac-mPGES-1-KO aortas. Consistently, in vitro experiments showed that expression of pro-inflammatory cytokines and MMPs was significantly reduced when mPGES-1 was lacking in the primary cultured peritoneal macrophages. These data altogether demonstrated that deletion of mPGES-1 in myeloid cells may attenuate AAA formation and targeting myeloid cell mPGES-1 could potentially offer an effective strategy for the treatment and prevention of vascular inflammatory diseases.

Epigenetic modifications in abdominal aortic aneurysms: from basic to clinical

Abdominal Aortic Aneurysm (AAA) is a disease characterized by localized dilation of the abdominal aorta, involving multiple factors in its occurrence and development, ultimately leading to vessel rupture and severe bleeding. AAA has a high mortality rate, and there is a lack of targeted therapeutic drugs. Epigenetic regulation plays a crucial role in AAA, and the treatment of AAA in the epigenetic field may involve a series of related genes and pathways. Abnormal expression of these genes may be a key factor in the occurrence of the disease and could potentially serve as promising therapeutic targets. Understanding the epigenetic regulation of AAA is of significant importance in revealing the mechanisms underlying the disease and identifying new therapeutic targets. This knowledge can contribute to offering AAA patients better clinical treatment options beyond surgery. This review systematically explores various aspects of epigenetic regulation in AAA, including DNA methylation, histone modification, non-coding RNA, and RNA modification. The analysis of the roles of these regulatory mechanisms, along with the identification of relevant genes and pathways associated with AAA, is discussed comprehensively. Additionally, a comprehensive discussion is provided on existing treatment strategies and prospects for epigenetics-based treatments, offering insights for future clinical interventions.

Macrophages in cardiovascular diseases: molecular mechanisms and therapeutic targets

The immune response holds a pivotal role in cardiovascular disease development. As multifunctional cells of the innate immune system, macrophages play an essential role in initial inflammatory response that occurs following cardiovascular injury, thereby inducing subsequent damage while also facilitating recovery. Meanwhile, the diverse phenotypes and phenotypic alterations of macrophages strongly associate with distinct types and severity of cardiovascular diseases, including coronary heart disease, valvular disease, myocarditis, cardiomyopathy, heart failure, atherosclerosis and aneurysm, which underscores the importance of investigating macrophage regulatory mechanisms within the context of specific diseases. Besides, recent strides in single-cell sequencing technologies have revealed macrophage heterogeneity, cell-cell interactions, and downstream mechanisms of therapeutic targets at a higher resolution, which brings new perspectives into macrophage-mediated mechanisms and potential therapeutic targets in cardiovascular diseases. Remarkably, myocardial fibrosis, a prevalent characteristic in most cardiac diseases, remains a formidable clinical challenge, necessitating a profound investigation into the impact of macrophages on myocardial fibrosis within the context of cardiac diseases. In this review, we systematically summarize the diverse phenotypic and functional plasticity of macrophages in regulatory mechanisms of cardiovascular diseases and unprecedented insights introduced by single-cell sequencing technologies, with a focus on different causes and characteristics of diseases, especially the relationship between inflammation and fibrosis in cardiac diseases (myocardial infarction, pressure overload, myocarditis, dilated cardiomyopathy, diabetic cardiomyopathy and cardiac aging) and the relationship between inflammation and vascular injury in vascular diseases (atherosclerosis and aneurysm). Finally, we also highlight the preclinical/clinical macrophage targeting strategies and translational implications.

High-density lipoprotein mimetic nano-therapeutics targeting monocytes and macrophages for improved cardiovascular care: a comprehensive review

The prevalence of cardiovascular diseases continues to be a challenge for global health, necessitating innovative solutions. The potential of high-density lipoprotein (HDL) mimetic nanotherapeutics in the context of cardiovascular disease and the intricate mechanisms underlying the interactions between monocyte-derived cells and HDL mimetic showing their impact on inflammation, cellular lipid metabolism, and the progression of atherosclerotic plaque. Preclinical studies have demonstrated that HDL mimetic nanotherapeutics can regulate monocyte recruitment and macrophage polarization towards an anti-inflammatory phenotype, suggesting their potential to impede the progression of atherosclerosis. The challenges and opportunities associated with the clinical application of HDL mimetic nanotherapeutics, emphasize the need for additional research to gain a better understanding of the precise molecular pathways and long-term effects of these nanotherapeutics on monocytes and macrophages to maximize their therapeutic efficacy. Furthermore, the use of nanotechnology in the treatment of cardiovascular diseases highlights the potential of nanoparticles for targeted treatments. Moreover, the concept of theranostics combines therapy and diagnosis to create a selective platform for the conversion of traditional therapeutic medications into specialized and customized treatments. The multifaceted contributions of HDL to cardiovascular and metabolic health via highlight its potential to improve plaque stability and avert atherosclerosis-related problems. There is a need for further research to maximize the therapeutic efficacy of HDL mimetic nanotherapeutics and to develop targeted treatment approaches to prevent atherosclerosis. This review provides a comprehensive overview of the potential of nanotherapeutics in the treatment of cardiovascular diseases, emphasizing the need for innovative solutions to address the challenges posed by cardiovascular diseases.

Incorporating machine learning and PPI networks to identify mitochondrial fission-related immune markers in abdominal aortic aneurysms

Purpose

The aim of this study is to investigate abdominal aortic aneurysm (AAA), a disease characterised by inflammation and progressive vasodilatation, for novel gene-targeted therapeutic loci.

Methods

To do this, we used weighted co-expression network analysis (WGCNA) and differential gene analysis on samples from the GEO database. Additionally, we carried out enrichment analysis and determined that the blue module was of interest. Additionally, we performed an investigation of immune infiltration and discovered genes linked to immune evasion and mitochondrial fission. In order to screen for feature genes, we used two PPI network gene selection methods and five machine learning methods. This allowed us to identify the most featrue genes (MFGs). The expression of the MFGs in various cell subgroups was then evaluated by analysis of single cell samples from AAA. Additionally, we looked at the expression levels of the MFGs as well as the levels of inflammatory immune-related markers in cellular and animal models of AAA. Finally, we predicted potential drugs that could be targeted for the treatment of AAA.

Results

Our research identified 1249 up-regulated differential genes and 3653 down-regulated differential genes. Through WGCNA, we also discovered 44 genes in the blue module. By taking the point where several strategies for gene selection overlap, the MFG (ITGAL and SELL) was produced. We discovered through single cell research that the MFG were specifically expressed in T regulatory cells, NK cells, B lineage, and lymphocytes. In both animal and cellular models of AAA, the MFGs' mRNA levels rose.

Conclusion

We searched for the AAA novel targeted gene (ITGAL and SELL), which most likely function through lymphocytes of the B lineage, NK cells, T regulatory cells, and B lineage. This analysis gave AAA a brand-new goal to treat or prevent the disease.

The JMJD family of histone demethylase and their intimate links to cardiovascular disease

The incidence rate and mortality rate of cardiovascular disease rank first in the world. It is associated with various high-risk factors, and there is no single cause. Epigenetic modifications, such as DNA methylation or histone modification, actively participate in the initiation and development of cardiovascular diseases. Histone lysine methylation is a type of histone post-translational modification. The human Jumonji C domain (JMJD) protein family consists of more than 30 members. JMJD proteins participate in many key nuclear processes and play a key role in the specific regulation of gene expression, DNA damage and repair, and DNA replication. Importantly, increasing evidence shows that JMJD proteins are abnormally expressed in cardiovascular diseases, which may be a potential mechanism for the occurrence and development of these diseases. Here, we discuss the key roles of JMJD proteins in various common cardiovascular diseases. This includes histone lysine demethylase, which has been studied in depth, and less-studied JMJD members. Furthermore, we focus on the epigenetic changes induced by each JMJD member, summarize recent research progress, and evaluate their relationship with cardiovascular diseases and therapeutic potential.

Calprotectin as a new inflammatory marker of abdominal aortic aneurysm: A pilot study

INTRODUCTION

Abdominal aortic aneurysm (AAA) is a relevant clinical problem due to the risk of rupture of progressively dilated infrarenal aorta. It is characterized by degradation of elastic fibers, extracellular matrix, and inflammation of the arterial wall. Though neutrophil infiltration is a known feature of AAA, markers of neutrophil activation are scarcely analyzed; hence, the main objective of this study.

METHODS

Plasma levels of main neutrophil activation markers were quantified in patients with AAA and a double control group (CTL) formed by healthy volunteers (HV) and patients with severe atherosclerosis submitted for carotid endarterectomy (CE). Calprotectin, a cytoplasmic neutrophil protein, was quantified, by Western blot, in arterial tissue samples from patients with AAA and organ donors. Colocalization of calprotectin and neutrophil elastase was assessed by immunofluorescence.

RESULTS

Plasma calprotectin and IL-6 were both elevated in patients with AAA compared with CTL (p ⩽ 0.0001) and a strong correlation was found between both molecules (p < 0.001). This difference was maintained when comparing with HV and CE for calprotectin but only with HV for IL-6. Calprotectin was also elevated in arterial tissue samples from patients with AAA compared with organ donors (p < 0.0001), and colocalized with neutrophils in the arterial wall.

CONCLUSIONS

Circulating calprotectin could be a specific AAA marker and a potential therapeutical target. Calprotectin is related to inflammation and neutrophil activation in arterial wall and independent of other atherosclerotic events.

The occurrence and development of abdominal aortic aneurysm may be related to the energy metabolism disorder and local inflammation

Background

The cellular mechanism of the formation of abdominal aortic aneurysm (AAA) is very complicated. A series of sophisticated events eventually led to significant pathological changes in the anatomical structure and function of the arterial wall and they are still not clear nowadays.

Methods

We pooled publicly available GEO datasets (GSE57691 and GSE47472) to get a comprehensive comparisons between normal tissues and AAA tissues to try to reveal molecular mechanism underlying the disease. Total 63 AAA samples and 18 normal tissue samples were compared and we fond that there were 784 significantly different gene (DEGs, threshold set as adjusted P < 0.05 and Log FC < 1) were identified. At the same time, we validate the possible signaling factor expression of AAA by comparing the normal tissue of the human body with the AAA tissue.

Results

In the pathway enrichment, we found that FOXP3 related signaling pathways, inflammation-related cytokine signaling pathways, interleukin-8-CXCR1 related signaling pathways and VEGFA and FGFR1 related signal pathway were significantly enrichmented. In Weighted gene co-expression network analysis (WGCNA), we found that the key hub genes were significantly related to lipid catabolic metabolism, which further verified the possibility that AAA might relate to energy metabolism disorders.

Conclusion

Based on the comprehensive analysis of previous high-throughput data and the validation of basic experiments, we found that the occurrence of AAA may be related to energy metabolism disorders and local inflammation.

The molecular mechanism of thrombospondin family members in cardiovascular diseases

Cardiovascular diseases have been identified as vital factors in global morbidity and mortality in recent years. The available evidence suggests that various cytokines and pathological proteins participate in these complicated and changeable diseases. The thrombospondin (TSP) family is a series of conserved, multidomain calcium-binding glycoproteins that cause cell-matrix and cell-cell effects via interactions with other extracellular matrix components and cell surface receptors. The TSP family has five members that can be divided into two groups (Group A and Group B) based on their different structures. TSP-1, TSP-2, and TSP-4 are the most studied proteins. Among recent studies and findings, we investigated the functions of several family members, especially TSP-5. We review the basic concepts of TSPs and summarize the relevant molecular mechanisms and cell interactions in the cardiovascular system. Targeting TSPs in CVD and other diseases has a remarkable therapeutic benefit.

Predicting feature genes correlated with immune infiltration in patients with abdominal aortic aneurysm based on machine learning algorithms

Abdominal aortic aneurysm (AAA) is a condition characterized by a pathological and progressive dilatation of the infrarenal abdominal aorta. The exploration of AAA feature genes is crucial for enhancing the prognosis of AAA patients. Microarray datasets of AAA were downloaded from the Gene Expression Omnibus database. A total of 43 upregulated differentially expressed genes (DEGs) and 32 downregulated DEGs were obtained. Function, pathway, disease, and gene set enrichment analyses were performed, in which enrichments were related to inflammation and immune response. AHR, APLNR, ITGA10 and NR2F6 were defined as feature genes via machine learning algorithms and a validation cohort, which indicated high diagnostic abilities by the receiver operating characteristic curves. The cell-type identification by estimating relative subsets of RNA transcripts (CIBERSORT) method was used to quantify the proportions of immune infiltration in samples of AAA and normal tissues. We have predicted AHR, APLNR, ITGA10 and NR2F6 as feature genes of AAA. CD8 + T cells and M2 macrophages correlated with these genes may be involved in the development of AAA, which have the potential to be developed as risk predictors and immune interventions.

Single-cell transcriptomics reveal the remodeling landscape of bladder in patients with obstruction-induced detrusor underactivity

Detrusor underactivity (DUA) is a common and thorny problem in urology, which severely impairs patients' bladder function and quality of life. However, its underlying pathophysiological mechanism remains unclear. Hence, we sequenced 69,973 cells from five controls and nine patients with bladder dysfunction using single-cell RNA sequencing. Twelve distinct cell types were identified and they showed high cellular and functional heterogeneity among each group. Among them, fibroblasts, macrophages, and epithelial cells had the most intercellular communications. Their aberrant gene expressions and altered intercellular interactions were mainly involved in extracellular matrix organization, inflammation/immune regulation, and cellular injury. Further re-cluster analysis revealed an accumulation of the RBFOX1+ fibroblasts and RIPOR2+ macrophages in dysfunctional bladder wall, which mediated bladder remodeling through dysfunctional extracellular matrix organization and inflammation/immune reaction. Besides, the subtype of the epithelial cells was significantly altered. They underwent an intricate process including inflammation, damage, and repair during bladder remodeling. Overall, this work constructed the first single-cell atlas for obstruction-induced DUA, which could provide a valuable resource for deciphering the cellular heterogeneity and function changes in DUA, as well as potential strategies for bladder function improvement.

The perspective of cAMP/cGMP signaling and cyclic nucleotide phosphodiesterases in aortic aneurysm and dissection

Aortic aneurysm (AA) and dissection (AD) are aortic diseases caused primarily by medial layer degeneration and perivascular inflammation. They are lethal when the rupture happens. Vascular smooth muscle cells (SMCs) play critical roles in the pathogenesis of medial degeneration, characterized by SMC loss and elastin fiber degradation. Many molecular pathways, including cyclic nucleotide signaling, have been reported in regulating vascular SMC functions, matrix remodeling, and vascular structure integrity. Intracellular cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) are second messengers that mediate intracellular signaling transduction through activating effectors, such as protein kinase A (PKA) and PKG, respectively. cAMP and cGMP are synthesized by adenylyl cyclase (AC) and guanylyl cyclase (GC), respectively, and degraded by cyclic nucleotide phosphodiesterases (PDEs). In this review, we will discuss the roles and mechanisms of cAMP/cGMP signaling and PDEs in AA/AD formation and progression and the potential of PDE inhibitors in AA/AD, whether they are beneficial or detrimental. We also performed database analysis and summarized the results showing PDEs with significant expression changes under AA/AD, which should provide rationales for future research on PDEs in AA/AD.

Revealing PPP1R12B and COL1A1 as piRNA pathway genes contributing to abdominal aortic aneurysm through integrated analysis and experimental validation

BACKGROUND

Abdominal aortic aneurysm (AAA) is a permanent dilation of the abdominal aorta, with a high mortality rate when rupturing. Although lots of piRNA pathway genes (piRPGs) have recently been linked to both neoplastic and non-neoplastic illnesses, their role in AAA is still unknown. Utilizing integrative bioinformatics methods, this research discovered piRPGs as biomarkers for AAA and explore possible molecular mechanisms.

METHODS

The datasets were obtained from the Gene Expression Omnibus and piRPGs were identified from the Genecards database. The "limma" and "clusterProfiler" R-packages were used to discover differentially expressed genes and perform enrichment analysis, respectively. Hub piRPGs were further filtered using least absolute shrinkage and selection operator regression, random forests, as well as receiver operating characteristic curve. Additionally, multi-factor logistic regression (MLR), extreme gradient boosting (XGboost), and artificial neural network (ANN) were employed to construct prediction models. The relationship between hub piRPGs and immune infiltrating cells and sgGSEA were further studied. The expression of hub piRPGs was verified by qRT-PCR, immunohistochemistry, and western blotting in AAA and normal vascular tissues and analyzed by scRNA-seq in mouse AAA model. SRAMP and cMAP database were utilized for the prediction of N6-methyladenosine (m6A) targets therapeutic drug.

RESULTS

34 differentially expressed piRPGs were identified in AAA and enriched in pathways of immune regulation and gene silence. Three piRPGs (PPP1R12B, LRP10, and COL1A1) were further screened as diagnostic genes and used to construct prediction model. Compared with MLR and ANN, Xgboost showed better predictive ability, and PPP1R12B might have the ability to distinguish small and large AAA. Furthermore, the expression levels of PPP1R12B and COL1A1 were consistent with the results of bioinformatics analysis, and PPP1R12B showed a downward trend that may be related to m6A.

CONCLUSION

The results suggest that piRPGs might serve a significant role in AAA. PPP1R12B, COL1A1, and LRP10 had potential as diagnostic-specific biomarkers for AAA and performed better in XGboost model. The expression and localization of PPP1R12B and COL1A1 were experimentally verified. Besides, downregulation of PPP1R12B caused by m6A might contribute to the formation of AAA.

Trained Innate Immunity in Animal Models of Cardiovascular Diseases

Acquisition of immunological memory is an important evolutionary strategy that evolved to protect the host from repetitive challenges from infectious agents. It was believed for a long time that memory formation exclusively occurs in the adaptive part of the immune system with the formation of highly specific memory T cells and B cells. In the past 10-15 years, it has become clear that innate immune cells, such as monocytes, natural killer cells, or neutrophil granulocytes, also have the ability to generate some kind of memory. After the exposure of innate immune cells to certain stimuli, these cells develop an enhanced secondary response with increased cytokine secretion even after an encounter with an unrelated stimulus. This phenomenon has been termed trained innate immunity (TI) and is associated with epigenetic modifications (histone methylation, acetylation) and metabolic alterations (elevated glycolysis, lactate production). TI has been observed in tissue-resident or circulating immune cells but also in bone marrow progenitors. Risk-factors for cardiovascular diseases (CVDs) which are associated with low-grade inflammation, such as hyperglycemia, obesity, or high salt, can also induce TI with a profound impact on the development and progression of CVDs. In this review, we briefly describe basic mechanisms of TI and summarize animal studies which specifically focus on TI in the context of CVDs.

Multimodality magnetic resonance evaluating the effect of enhanced physical exercise on the growth rate, flow haemodynamics, aneurysm wall and ventricular-aortic coupling of patients with small abdominal aortic aneurysms (AAA MOVE trial): a study protocol for an open-label randomised controlled trial

INTRODUCTION

The best lifestyle for small abdominal aortic aneurysms (sAAA) is essential for its conservative management. Physical exercise can improve the cardiopulmonary function of the patients, but it remains unclear which specific type of exercise is most beneficial for individuals with sAAA. The current study was designed to investigate the effect of physician-guided enhanced physical exercise programme on the aorto-cardiac haemodynamic environment, aneurysm sac wall, cardiac function and growth rate of sAAA by multimodality MRI.

METHODS AND ANALYSIS

AAA MOVE study is a prospective, parallel, equivalence, randomised controlled trial. Eligible individuals will be recruited if they are diagnosed with sAAA (focal dilation of abdominal aorta with maximum diameter <5 cm), without contraindication for MRI scanning, or severe heart failure, or uncontrolled arrhythmia. Participants will be randomly allocated to intervention group (physician-guided enhanced physical exercise programme: mainly aerobic training) and control group (standard clinical care) separately in a 1:1 ratio. The primary outcome is 12-month growth rate of sAAA. The first set of secondary outcomes involve multimodality MRI parameters covering flow haemodynamics, aortic wall inflammation and cardiac function. The other secondary outcome (safety end point) is a composite of exercise-related injury, aneurysm rupture and aneurysm intervention. Follow-up will be conducted at 6 and 12 months after intervention.

ETHICS AND DISSEMINATION

This study was approved by the Ethics Committee on Biomedical Research of West China Hospital (approval number: 2023-783) on 16 June 2023. Main findings from the trial will be disseminated through presentations at conferences, peer-reviewed publications and directly pushed to smartphone of participants.

TRIAL REGISTRATION NUMBER

ChiCTR2300073334.

The Preoperative Lymphocyte-To-Monocyte Ratio Predicts Mortality Among Patients Undergoing Endovascular Aortic Repair for Abdominal Aortic Aneurysm

PURPOSE

The purpose of this study was to investigate the preoperative lymphocyte-to-monocyte ratio (LMR) as a potential surrogate biomarker predictive of overall mortality in patients undergoing endovascular aortic repair (EVAR) for abdominal aortic aneurysm (AAA).

METHODS

Data on patients with AAA treated by EVAR between March 2012 and December 2016 were obtained from a prospectively maintained EVAR database at Tokyo Medical University Hospital, Tokyo, Japan. The LMR was calculated by dividing the absolute lymphocyte count by the absolute monocyte count.

RESULTS

One hundred seventy-six patients were included in this study after selection based on the exclusion criteria. The subjects consisted of 148 males and 28 females with a mean age of 78.5 years (range, 51-89 years). The median follow-up period was 4.98 years (range, .03-9.28). A receiver operating characteristic curve analysis determined the optimal cut-off value of the preoperative LMR for predicting overall mortality with 3.21 (area under the curve, .71; 95% confidence interval [CI], .62-.79; sensitivity, 57.4%; specificity, 77.0%; P < .001). On univariable and multivariable analyses, octogenarian (hazard ratio [HR], 1.89; 95%CI, 1.10-3.22; P = .020), poor nutritional status (HR, 2.95; 95%CI, 1.73-5.03; P < .001), chronic obstructive pulmonary disease (HR, 1.79; 95%CI, 1.06-3.03; P = .031), active cancer (HR, 2.60; 95%CI, 1.53-4.41; P < .001), and low preoperative LMR (HR, 2.56; 95%CI, 1.53-4.30; P < .001) were identified as independent predictors for overall mortality.

CONCLUSION

This study showed that a low preoperative LMR (<3.21) is an independent predictor of overall mortality after EVAR for AAA. The LMR may help in decision-making regarding the prediction of poor prognosis after EVAR.

Innate immunity of vascular smooth muscle cells contributes to two-wave inflammation in atherosclerosis, twin-peak inflammation in aortic aneurysms and trans-differentiation potential into 25 cell types

Introduction

Vascular smooth muscle cells (VSMCs) are the predominant cell type in the medial layer of the aorta, which plays a critical role in aortic diseases. Innate immunity is the main driving force for cardiovascular diseases.

Methods

To determine the roles of innate immunity in VSMC and aortic pathologies, we performed transcriptome analyses on aortas from ApoE-/- angiotensin II (Ang II)-induced aortic aneurysm (AAA) time course, and ApoE-/- atherosclerosis time course, as well as VSMCs stimulated with danger-associated molecular patterns (DAMPs).

Results

We made significant findings: 1) 95% and 45% of the upregulated innate immune pathways (UIIPs, based on data of 1226 innate immune genes) in ApoE-/- Ang II-induced AAA at 7 days were different from that of 14 and 28 days, respectively; and AAA showed twin peaks of UIIPs with a major peak at 7 days and a minor peak at 28 days; 2) all the UIIPs in ApoE-/- atherosclerosis at 6 weeks were different from that of 32 and 78 weeks (two waves); 3) analyses of additional 12 lists of innate immune-related genes with 1325 cytokine and chemokine genes, 2022 plasma membrane protein genes, 373 clusters of differentiation (CD) marker genes, 280 nuclear membrane protein genes, 1425 nucleoli protein genes, 6750 nucleoplasm protein genes, 1496 transcription factors (TFs) including 15 pioneer TFs, 164 histone modification enzymes, 102 oxidative cell death genes, 68 necrotic cell death genes, and 47 efferocytosis genes confirmed two-wave inflammation in atherosclerosis and twin-peak inflammation in AAA; 4) DAMPs-stimulated VSMCs were innate immune cells as judged by the upregulation of innate immune genes and genes from 12 additional lists; 5) DAMPs-stimulated VSMCs increased trans-differentiation potential by upregulating not only some of 82 markers of 7 VSMC-plastic cell types, including fibroblast, osteogenic, myofibroblast, macrophage, adipocyte, foam cell, and mesenchymal cell, but also 18 new cell types (out of 79 human cell types with 8065 cell markers); 6) analysis of gene deficient transcriptomes indicated that the antioxidant transcription factor NRF2 suppresses, however, the other five inflammatory transcription factors and master regulators, including AHR, NF-KB, NOX (ROS enzyme), PERK, and SET7 promote the upregulation of twelve lists of innate immune genes in atherosclerosis, AAA, and DAMP-stimulated VSMCs; and 7) both SET7 and trained tolerance-promoting metabolite itaconate contributed to twin-peak upregulation of cytokines in AAA.

Discussion

Our findings have provided novel insights on the roles of innate immune responses and nuclear stresses in the development of AAA, atherosclerosis, and VSMC immunology and provided novel therapeutic targets for treating those significant cardiovascular and cerebrovascular diseases.

Current understanding of macrophages in intracranial aneurysm: relevant etiological manifestations, signaling modulation and therapeutic strategies

Macrophages activation and inflammatory response play crucial roles in intracranial aneurysm (IA) formation and progression. The outcome of ruptured IA is considerably poor, and the mechanisms that trigger IA progression and rupture remain to be clarified, thereby developing effective therapy to prevent subarachnoid hemorrhage (SAH) become difficult. Recently, climbing evidences have been expanding our understanding of the macrophages relevant IA pathogenesis, such as immune cells population, inflammatory activation, intra-/inter-cellular signaling transductions and drug administration responses. Crosstalk between macrophages disorder, inflammation and cellular signaling transduction aggravates the devastating consequences of IA. Illustrating the pros and cons mechanisms of macrophages in IA progression are expected to achieve more efficient treatment interventions. In this review, we summarized the current advanced knowledge of macrophages activation, infiltration, polarization and inflammatory responses in IA occurrence and development, as well as the most relevant NF-κB, signal transducer and activator of transcription 1 (STAT1) and Toll-Like Receptor 4 (TLR4) regulatory signaling modulation. The understanding of macrophages regulatory mechanisms is important for IA patients' clinical outcomes. Gaining insight into the macrophages regulation potentially contributes to more precise IA interventions and will also greatly facilitate the development of novel medical therapy.

The future for the therapeutics of abdominal aortic aneurysm: engineered nanoparticles drug delivery for abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a severe cardiovascular disease with a high mortality rate. Several screening and diagnostic methods have been developed for AAA early diagnosis. Open surgery and endovascular aortic repair (EVAR) are clinically available for patients who meet the indications for surgery. However, for non-surgical patients, limited drugs exist to inhibit or reverse the progression of aneurysms due to the complex pathogenesis and biological structure of AAA, failing to accumulate precisely on the lesion to achieve sufficient concentrations. The recently developed nanotechnology offers a new strategy to address this problem by developing drug-carrying nanoparticles with enhanced water solubility and targeting capacity, prolonged duration, and reduced side effects. Despite the rising popularity, limited literature is available to highlight the progression of the field. Herein, in this review, we first discuss the pathogenesis of AAA, the methods of diagnosis and treatment that have been applied clinically, followed by the review of research progressions of constructing different drug-loaded nanoparticles for AAA treatment using engineered nanoparticles. In addition, the feasibility of extracellular vesicles (EVs) and EVs-based nanotechnology for AAA treatment in recent years are highlighted, together with the future perspective. We hope this review will provide a clear picture for the scientists and clinicians to find a new solution for AAA clinical management.

IRF5 governs macrophage adventitial infiltration to fuel abdominal aortic aneurysm formation

Abdominal aortic aneurysm (AAA) is a chronic inflammatory disease characterized by the expansion of the aortic wall. One of the most significant features is the infiltration of macrophages in the adventitia, which drives vasculature remodeling. The role of macrophage-derived interferon regulatory factor 5 (IRF5) in macrophage infiltration and AAA formation remains unknown. RNA sequencing of AAA adventitia identified Irf5 as the top significantly increased transcription factor that is predominantly expressed in macrophages. Global and myeloid cell-specific deficiency of Irf5 reduced AAA progression, with a marked reduction in macrophage infiltration. Further cellular investigations indicated that IRF5 promotes macrophage migration by direct regulation of downstream phosphoinositide 3-kinase γ (PI3Kγ, Pik3cg). Pik3cg ablation hindered AAA progression, and myeloid cell-specific salvage of Pik3cg restored AAA progression and macrophage infiltration derived from Irf5 deficiency. Finally, we found that IRF5 and PI3Kγ expression in the adventitia is significantly increased in patients with AAA. These findings reveal that the IRF5-dependent regulation of PI3Kγ is essential for AAA formation.

Antioxidants and azd0156 Rescue Inflammatory Response in Autophagy-Impaired Macrophages

Autophagy is a lysosomal degradation system that eliminates and recycles damaged intracellular organelles and proteins. Inflammatory macrophages play a critical role in the development of various age-related inflammatory illnesses such as abdominal aortic aneurysm, atherosclerosis, and rheumatoid arthritis; therefore, identifying the mechanisms that cause macrophage inflammation is crucial for a better understanding of and developing therapeutics for inflammatory diseases. Previous research has linked autophagy to macrophage inflammation; Atg16L1-deficient macrophages increase IL-1 and IL-18 production via inflammasome activation. In this study, however, we show an alternative pathway of macrophage inflammation in an autophagy-deficient environment. We found that inhibiting autophagy in THP1 macrophages progressively increased the expression of p65-mediated inflammatory genes. This effect was reversed by treatment with antioxidants or azd0156, an ataxia telangiectasia mutated (ATM) inhibitor. In addition, our results showed that M1 macrophages inhibit autophagy and induce DNA damage, whereas M2 macrophages activate autophagy and reduce DNA damage. Importantly, the chemical activation of autophagy or ATM inhibition during M1 polarization reduced the M1 phenotype and inflammation, whereas inhibiting autophagy during M2 polarization also reduced the M2 phenotype. Thus, our findings highlight the importance of the autophagy-ATM pathway in driving macrophage inflammation.

Diagnostic Utility of a Combined MPO/D-Dimer Score to Distinguish Abdominal Aortic Aneurysm from Peripheral Artery Disease

Abdominal aortic aneurysm (AAA) and peripheral artery disease (PAD) share pathophysiological mechanisms including the activation of the fibrinolytic and innate immune system, which explains the analysis of D-dimer and myeloperoxidase (MPO) in both conditions. This study evaluates the diagnostic marker potential of both variables separately and as a combined MPO/D-dimer score for identifying patients with AAA versus healthy individuals or patients with PAD. Plasma levels of MPO and D-dimer were increased in PAD and AAA compared to healthy controls (median for MPO: 13.63 ng/mL [AAA] vs. 11.74 ng/mL [PAD] vs. 9.16 ng/mL [healthy], D-dimer: 1.27 μg/mL [AAA] vs. 0.58 μg/mL [PAD] vs. 0.38 μg/mL [healthy]). The combined MPO/D-dimer score (median 1.26 [AAA] vs. -0.19 [PAD] vs. -0.93 [healthy]) showed an improved performance in distinguishing AAA from PAD when analysed using the receiver operating characteristic curve (area under the curve) for AAA against the pooled data of healthy controls + PAD: 0.728 [MPO], 0.749 [D-dimer], 0.801 [score]. Diagnostic sensitivity and specificity ranged at 82.9% and 70.2% (for score cut-off = 0). These findings were confirmed for a separate collective of AAA patients with 35% simultaneous PAD. Thus, evaluating MPO together with D-dimer in a simple score may be useful for diagnostic detection and the distinction of AAA from athero-occlusive diseases like PAD.

Chemokine Receptor 2 Is A Theranostic Biomarker for Abdominal Aortic Aneurysms

Abdominal aortic aneurysm (AAA) is a degenerative vascular disease impacting aging populations with a high mortality upon rupture. There are no effective medical therapies to prevent AAA expansion and rupture. We previously demonstrated the role of the monocyte chemoattractant protein-1 (MCP-1) / C-C chemokine receptor type 2 (CCR2) axis in rodent AAA pathogenesis via positron emission tomography/computed tomography (PET/CT) using CCR2 targeted radiotracer 64 Cu-DOTA-ECL1i. We have since translated this radiotracer into patients with AAA. CCR2 PET showed intense radiotracer uptake along the AAA wall in patients while little signal was observed in healthy volunteers. AAA tissues collected from individuals scanned with 64 Cu-DOTA-ECL1i and underwent open-repair later demonstrated more abundant CCR2+ cells compared to non-diseased aortas. We then used a CCR2 inhibitor (CCR2i) as targeted therapy in our established male and female rat AAA rupture models. We observed that CCR2i completely prevented AAA rupture in male rats and significantly decreased rupture rate in female AAA rats. PET/CT revealed substantial reduction of 64 Cu-DOTA-ECL1i uptake following CCR2i treatment in both rat models. Characterization of AAA tissues demonstrated decreased expression of CCR2+ cells and improved histopathological features. Taken together, our results indicate the potential of CCR2 as a theranostic biomarker for AAA management.

Comprehensive bioinformatics analysis revealed potential key genes and pathways underlying abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a permanent, asymptomatic segmental dilatation of the abdominal aorta, with a high mortality risk upon rupture. Identification of potential key genes and pathways may help to develop curative drugs for AAA. We conducted RNA-seq on abdominal aortic tissues from both AAA patients and normal individuals as a control group. Integrated bioinformatic analysis was subsequently performed to comprehensively reveal potential key genes and pathways. A total of 1148 differential expressed genes (DEGs) (631 up-regulated and 517 down-regulated) were identified in our study. Gene Ontology (GO) analysis revealed enrichment in terms related to extracellular matrix organization, while KEGG analysis indicated enrichment in hematopoietic cell lineage and ECM-receptor interaction. Protein-protein interaction (PPI) network analysis revealed several candidate key genes, and differential expression of 6 key genes (CXCL8, CCL2, PTGS2, SELL, CCR7, and CXCL1) was validated by Gene Expression Omnibus (GEO) datasets. Receiver operating characteristic curve (ROC) analysis demonstrated these genes' high discriminatory ability between AAA and normal tissues. Immunohistochemistry indicated that several key genes were highly expressed in AAA tissues. Single-cell RNA sequencing revealed differential distribution patterns of these identified key genes among various cell types. 26 potential drugs linked to our key genes were found through DGIdb. Overall, our study provides a comprehensive evaluation of potential key genes and pathways in AAA, which could pave the way for the development of curative pharmacological therapies.

3, 4-Benzopyrene (Bap) aggravated abdominal aortic aneurysm formation by targeting pyroptosis in smooth muscle cells through ET-1 mediated NLRP3-inflammasome activation

According to epidemiological studies, smoking is one of the leading causes of the high incidence of abdominal aortic aneurysms (AAA).3,4-Benzopyrene (Bap) is a by-product of coal tar and tobacco combustion produced by the incomplete combustion of organic fuels. It is an essential component of both automobile exhaust and tobacco smoke, it is also an important member of the air pollutants. However, the exact mechanism by which Bap can worsen the condition of patients with AAA and increase the mortality of patients with AAA remains unknown. This research aims to investigate the role of Bap in inducing pyroptosis in AAA. In vitro experiments, we revealed that pyroptosis-Gasdermin D (GSDMD) increased when Bap was used. Additionally, the release of inflammatory factors, such as IL-1β and IL-18 were also rising. An mRNA sequencing analysis revealed that macrophages expressed a high level of the endothelin gene when cells were stimulated by Bap. It seemed that smooth muscle cells pyroptosis was related to macrophages. Experiments revealed that endothelin could increase the calcium ion concentration in smooth muscle cells, resulting in a large amount of ROS and activation of NLRP3 inflammasomes. We discovered that treatment with endothelin receptor antagonist (ABT-546) in vivo and calcium ion chelator (BAPTA) in vitro decreased AAA diameter, downregulated NLRP3 inflammasomes and ROS, and significantly reduced the number of activated GSDMD. Inflammatory mediators were released at a lower level. These findings suggest that Bap-induced pyroptosis may be mediated by the ET-1-Ca2+-inflammasome pathway, providing a new way to reduce mortality in AAA patients.

CD73 deficiency does not aggravate angiotensin II-induced aortic inflammation in mice

Vascular inflammation plays a key role in the development of aortic diseases. A potential novel target for treatment might be CD73, an ecto-5'-nucleotidase that generates anti-inflammatory adenosine in the extracellular space. Here, we investigated whether a lack of CD73 results in enhanced aortic inflammation. To this end, angiotensin II was infused into wildtype and CD73-/- mice over 10 days. Before and after infusion, mice were analyzed using magnetic resonance imaging, ultrasound, flow cytometry, and histology. The impact of age and gender was investigated using female and male mice of three and six months of age, respectively. Angiotensin II infusion led to increased immune cell infiltration in both genotypes' aortae, but depletion of CD73 had no impact on immune cell recruitment. These findings were not modified by age or sex. No substantial difference in morphological or functional characteristics could be detected between wildtype and CD73-/- mice. Interestingly, the expression of CD73 on neutrophils decreased significantly in wildtype mice during treatment. In summary, we have found no evidence that CD73 deficiency affects the onset of aortic inflammation. However, as CD73 expression decreased during disease induction, an increase in CD73 by pharmaceutical intervention might result in lower vascular inflammation and less vascular disease.

Machine Learning and Omics Analysis in Aortic Aneurysm

Aortic aneurysm is a life-threatening condition and mechanisms underlying its formation and progression are still incompletely understood. Omics approach has brought new insights to identify a broad spectrum of biomarkers and better understand cellular and molecular pathways involved. Omics generate a large amount of data and several studies have highlighted that artificial intelligence (AI) and techniques such as machine learning (ML)/deep learning (DL) can be of use in analyzing such complex datasets. However, only a few studies have so far reported the use of ML/DL for omics analysis in aortic aneurysms. The aim of this study is to summarize recent advances on the use of ML/DL for omics analysis to decipher aortic aneurysm pathophysiology and develop patient-tailored risk prediction models. In the light of current knowledge, we discuss current limits and highlight future directions in the field.

C-reactive protein deficiency ameliorates experimental abdominal aortic aneurysms

Background

C-reactive protein (CRP) levels are elevated in patients with abdominal aortic aneurysms (AAA). However, it has not been investigated whether CRP contributes to AAA pathogenesis.

Methods

CRP deficient and wild type (WT) male mice were subjected to AAA induction via transient intra-aortic infusion of porcine pancreatic elastase. AAAs were monitored by in situ measurements of maximal infrarenal aortic external diameters immediately prior to and 14 days following elastase infusion. Key AAA pathologies were assessed by histochemical and immunohistochemical staining procedures. The influence of CRP deficiency on macrophage activation was evaluated in peritoneal macrophages in vitro.

Results

CRP protein levels were higher in aneurysmal than that in non-aneurysmal aortas. Aneurysmal aortic dilation was markedly suppressed in CRP deficient (aortic diameter: 1.08 ± 0.11 mm) as compared to WT (1.21 ± 0.08 mm) mice on day 14 after elastase infusion. More medial elastin was retained in CRP deficient than in WT elastase-infused mice. Macrophage accumulation was significantly less in aneurysmal aorta from CRP deficient than that from WT mice. Matrix metalloproteinase 2 expression was also attenuated in CRP deficient as compared to WT aneurysmal aortas. CRP deficiency had no recognizable influence on medial smooth muscle loss, lymphocyte accumulation, aneurysmal angiogenesis, and matrix metalloproteinase 9 expression. In in vitro assays, mRNA levels for tumor necrosis factor α and cyclooxygenase 2 were reduced in lipopolysaccharide activated peritoneal macrophages from CRP deficient as compared to wild type mice.

Conclusion

CRP deficiency suppressed experimental AAAs by attenuating aneurysmal elastin destruction, macrophage accumulation and matrix metalloproteinase 2 expression.

A role of inflammaging in aortic aneurysm: new insights from bioinformatics analysis

Introduction

Aortic aneurysms (AA) are prevalent worldwide with a notable absence of drug therapies. Thus, identifying potential drug targets is of utmost importance. AA often presents in the elderly, coupled with consistently raised serum inflammatory markers. Given that ageing and inflammation are pivotal processes linked to the evolution of AA, we have identified key genes involved in the inflammaging process of AA development through various bioinformatics methods, thereby providing potential molecular targets for further investigation.

Methods

The transcriptome data of AA was procured from the datasets GSE140947, GSE7084, and GSE47472, sourced from the NCBI GEO database, whilst gene data of ageing and inflammation were obtained from the GeneCards Database. To identify key genes, differentially expressed analysis using the "Limma" package and WGCNA were implemented. Protein-protein intersection (PPI) analysis and machine learning (ML) algorithms were employed for the screening of potential biomarkers, followed by an assessment of the diagnostic value. Following the acquisition of the hub inflammaging and AA-related differentially expressed genes (IADEGs), the TFs-mRNAs-miRNAs regulatory network was established. The CIBERSORT algorithm was utilized to investigate immune cell infiltration in AA. The correlation of hub IADEGs with infiltrating immunocytes was also evaluated. Lastly, wet laboratory experiments were carried out to confirm the expression of hub IADEGs.

Results

342 and 715 AA-related DEGs (ADEGs) recognized from GSE140947 and GSE7084 datasets were procured by intersecting the results of "Limma" and WGCNA analyses. After 83 IADEGs were obtained, PPI analysis and ML algorithms pinpointed 7 and 5 hub IADEGs candidates respectively, and 6 of them demonstrated a high diagnostic value. Immune cell infiltration outcomes unveiled immune dysregulation in AA. In the wet laboratory experiments, 3 hub IADEGs, including BLNK, HLA-DRA, and HLA-DQB1, finally exhibited an expression trend in line with the bioinformatics analysis result.

Discussion

Our research identified three genes - BLNK, HLA-DRA, and HLA-DQB1- that play a significant role in promoting the development of AA through inflammaging, providing novel insights into the future understanding and therapeutic intervention of AA.

Micro- and Macrovascular Effects of Inflammation in Peripheral Artery Disease-Pathophysiology and Translational Therapeutic Approaches

Inflammation has a critical role in the development and progression of atherosclerosis. On the molecular level, inflammatory pathways negatively impact endothelial barrier properties and thus, tissue homeostasis. Conformational changes and destruction of the glycocalyx further promote pro-inflammatory pathways also contributing to pro-coagulability and a prothrombotic state. In addition, changes in the extracellular matrix composition lead to (peri-)vascular remodelling and alterations of the vessel wall, e.g., aneurysm formation. Moreover, progressive fibrosis leads to reduced tissue perfusion due to loss of functional capillaries. The present review aims at discussing the molecular and clinical effects of inflammatory processes on the micro- and macrovasculature with a focus on peripheral artery disease.

Targeted PERK inhibition with biomimetic nanoclusters confers preventative and interventional benefits to elastase-induced abdominal aortic aneurysms

Abdominal aortic aneurysm (AAA) is a progressive aortic dilatation, causing ∼80% mortality upon rupture. Currently, there is no approved drug therapy for AAA. Surgical repairs are invasive and risky and thus not recommended to patients with small AAAs which, however, account for ∼90% of the newly diagnosed cases. It is therefore a compelling unmet clinical need to discover effective non-invasive strategies to prevent or slow down AAA progression. We contend that the first AAA drug therapy will only arise through discoveries of both effective drug targets and innovative delivery methods. There is substantial evidence that degenerative smooth muscle cells (SMCs) orchestrate AAA pathogenesis and progression. In this study, we made an exciting finding that PERK, the endoplasmic reticulum (ER) stress Protein Kinase R-like ER Kinase, is a potent driver of SMC degeneration and hence a potential therapeutic target. Indeed, local knockdown of PERK in elastase-challenged aorta significantly attenuated AAA lesions in vivo. In parallel, we also conceived a biomimetic nanocluster (NC) design uniquely tailored to AAA-targeting drug delivery. This NC demonstrated excellent AAA homing via a platelet-derived biomembrane coating; and when loaded with a selective PERK inhibitor (PERKi, GSK2656157), the NC therapy conferred remarkable benefits in both preventing aneurysm development and halting the progression of pre-existing aneurysmal lesions in two distinct rodent models of AAA. In summary, our current study not only establishes a new intervention target for mitigating SMC degeneration and aneurysmal pathogenesis, but also provides a powerful tool to facilitate the development of effective drug therapy of AAA.

Dysregulations of Key Regulators of Angiogenesis and Inflammation in Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is a chronic vascular disease caused by localized weakening and broadening of the abdominal aorta. AAA is a clearly underdiagnosed disease and is burdened with a high mortality rate (65-85%) from AAA rupture. Studies indicate that abnormal regulation of angiogenesis and inflammation contributes to progression and onset of this disease; however, dysregulations in the molecular pathways associated with this disease are not yet fully explained. Therefore, in our study, we aimed to identify dysregulations in the key regulators of angiogenesis and inflammation in patients with AAA in peripheral blood mononuclear cells (using qPCR) and plasma samples (using ELISA). Expression levels of ANGPT1, CXCL8, PDGFA, TGFB1, VEGFB, and VEGFC and plasma levels of TGF-alpha, TGF-beta 1, VEGF-A, and VEGF-C were found to be significantly altered in the AAA group compared to the control subjects without AAA. Associations between analyzed factors and risk factors or biochemical parameters were also explored. Any of the analyzed factors was associated with the size of the aneurysm. The presented study identified dysregulations in key angiogenesis- and inflammation-related factors potentially involved in AAA formation, giving new insight into the molecular pathways involved in the development of this disease and providing candidates for biomarkers that could serve as diagnostic or therapeutic targets.

Association of HIV Infection and Incident Abdominal Aortic Aneurysm Among 143 001 Veterans

BACKGROUND

People with HIV (PWH) have an increased risk of cardiovascular disease. Previous cross-sectional data suggest there is a higher prevalence of abdominal aortic aneurysm (AAA) in PWH than in those without HIV. Whether PWH have an increased risk of incident AAA compared with those without HIV is unknown.

METHODS

We analyzed data among participants without prevalent AAA from the Veterans Aging Cohort Study, a prospective, observational, longitudinal cohort of veterans with HIV matched 1:2 with veterans without HIV infection. We calculated AAA rates by HIV status and assessed the association between HIV infection and incident AAA using Cox proportional hazards models. We defined AAA using the International Classification of Diseases, 9th or 10th revision, or Current Procedural Terminology codes and adjusted all models for demographic characteristics, cardiovascular disease risk factors, and substance use. Secondary analyses examined the association between time-varying CD4+ T-cell count or HIV viral load and incident AAA.

RESULTS

Among 143 001 participants (43 766 with HIV), over a median follow-up of 8.7 years, there were 2431 incident AAA events (26.4% among PWH). Rates of incident AAA per 1000 person-years were similar among PWH (2.0 [95% CI, 1.9-2.2]) and people without HIV (2.2 [95% CI, 2.1-2.3]). There was no evidence that HIV infection increased the risk of incident AAA compared with no HIV infection (adjusted hazard ratio, 1.02 [95% CI, 0.92-1.13]). In adjusted analyses with time-varying CD4+ T-cell counts or HIV viral load, PWH with CD4+ T-cell counts <200 cells/mm3 (adjusted hazard ratio, 1.29 [95% CI, 1.02-1.65]) or HIV viral load ≥500 copies/mL (adjusted hazard ratio, 1.29 [95% CI, 1.09-1.52]) had an increased risk of AAA compared with those without HIV.

CONCLUSIONS

HIV infection is associated with an increased risk of AAA among those with low CD4+ T-cell counts or elevated HIV viral load over time.

The presence of activating IgG Fc receptors in macrophages aggravates the development of experimental abdominal aortic aneurysm

INTRODUCTION

Abdominal aortic aneurysm (AAA) is a multifactorial, degenerative disease characterized by progressive aortic dilation and chronic activation of inflammation, proteolytic activity, and oxidative stress in the aortic wall. The immune response triggered by antibodies against antigens present in the vascular wall participates in the formation and progression of AAA through mechanisms not completely understood. This work analyses the function of specific IgG receptors (FcγR), especially those expressed by monocytes/macrophages, in the development of experimental AAA.

METHODS

In the elastase-induced AAA model, the abdominal aortas from wildtype and FcγR deficient mice with/without macrophage adoptive transfer were analysed by histology and quantitative PCR. In vitro, mouse macrophages were transfected with RNA interference of FcγRIV/CD16.2 or treated with Syk kinase inhibitor before stimulation with IgG immune complexes.

RESULTS

Macrophage adoptive transfer in FcγR deficient mice increased the susceptibility to AAA development. Mice receiving macrophages with functional FcγR exhibited higher aortic diameter increase, higher content of macrophages and B lymphocytes, and upregulated expression of chemokine CCL2, cytokines (TNF-α and IL-17), metalloproteinase MMP2, prooxidant enzyme NADPH oxidase-2, and the isoforms FcγRIII/CD16 and FcγRIV/CD16.2. In vitro, both FcγRIV/CD16.2 gene silencing and Syk inhibition reduced cytokines and reactive oxygen species production induced by immune complexes in macrophages.

CONCLUSIONS

Activation of macrophage FcγR contributes to AAA development by inducing mediators of inflammation, proteolysis, and oxidative stress. Modulation of FcγR or effector molecules may represent a potential target for AAA treatment.

Macrophage scavenger receptor A1 antagonizes abdominal aortic aneurysm via upregulating IRG1

AIMS

Abdominal aortic aneurysm (AAA) is a common, usually asymptomatic disease with high mortality and limited therapeutic options. Extensive extracellular matrix (ECM) fragmentation and transmural inflammation act as major pathological processes of AAA. However, the underlying regulatory mechanisms remain incompletely understood. Herein, we aimed to investigate the role of scavenger receptor A1 (SR-A1), a key pattern recognition receptor modulating macrophage activity, in pathogenesis of AAA.

METHODS AND RESULTS

The AAA model was generated by administration of angiotensin II (Ang II) into apolipoprotein E knockout mice or peri-arterial application of calcium phosphate in C57BJ/6L mice. We found that SR-A1 was markedly down-regulated in the macrophages isolated from murine AAA aortas. Global or myeloid-specific ablation of SR-A1 aggravated vascular inflammation, loss of vascular smooth muscle cells and degradation of the extracellular matrix. These effects of SR-A1 deficiency on AAA development were mediated by suppressed immunoresponsive gene 1 (IRG1) and increased inflammatory response in macrophages. Mechanically, binding of SR-A1 with Lyn led to STAT3 phosphorylation and translocation into the nucleus, in which STAT3 promoted IRG1 transcription through directly binding to its promoter. Restoration of macrophage SR-A1 in SR-A1-deficient mice by bone marrow transplantation or administration of 4-octyl itaconate, the derivate of IRG1 product itaconate, could relieve murine AAA.

CONCLUSION

Our study reveals a protective effect of macrophage SR-A1-STAT3-IRG1 axis against aortic aneurysm formation via inhibiting inflammation.

Exploring the expression and potential function of follicle stimulating hormone receptor in extragonadal cells related to abdominal aortic aneurysm

INTRODUCTION

Follicle stimulating hormone (FSH) is identified to play a role in postmenopausal disease and hypothesized to affect abdominal aortic aneurysm (AAA) onset/progression in postmenopausal women. We aimed to detect FSHR gene expression in AAA tissue and cell types involved in AAA formation.

METHODS

FSH stimulation of human umbilical cord endothelial cells (HUVECs), smooth muscle cells (HUCs) and PMA-differentiated macrophages to assess gene expression of FSHR and various markers. Human macrophages activated with various stimuli were assessed for FSHR gene expression. AAA dataset, AAA tissue samples and AAA-derived smooth muscle cells (SMC) obtained from elderly female donors were assessed for FSHR gene expression. AAA-SMCs were stimulated with FSH to assess its effect on gene expression. Lastly, oxidized low-density-lipoprotein (ox-LDL) uptake and abundance of cell surface protein markers were assessed by flow cytometry after FSH stimulation of human monocytes.

RESULTS

FSH stimulation showed similar levels of gene expression in HUVECs and HUCs. Only ACTA2 was downregulated in HUCs. In PMA-differentiated macrophages, gene expression of inflammation markers was unchanged after FSH stimulation. FSHR gene expression was found to be low in the AAA datasets. Female AAA-SMCs show occasional FSHR gene expression at a very low level, yet stimulation with FSH did not affect gene expression of SMC- or inflammation markers. FSH stimulation did not impact ox-LDL uptake or alter cell surface protein expression in monocytes. While FSHR gene expression was detected in human testis tissue, it was below quantification level in all other investigated cell types, even upon activation of macrophages with various stimuli.

CONCLUSION

Despite previous reports, we did not detect FSHR gene expression in various extragonadal cell types, except in occasional female AAA-SMCs. No clear effect on cell activation was observed upon FSH stimulation in any cell type. Our data suggest that a direct effect of FSH in AAA-related extragonadal cells is unlikely to influence AAA.

lncRNA MIR503HG Targets miR-191-5p/PLCD1 Axis and Negatively Modulates Apoptosis, Extracellular Matrix Disruption, and Inflammation in Abdominal Aortic Aneurysm

As the most prevalent subtype of aortic aneurysm, abdominal aortic aneurysm (AAA) features the apoptosis, extracellular matrix (ECM) disruption, and inflammation response of vascular smooth muscle cells (VSMCs). Noncoding RNAs (ncRNAs) are crucial factors in AAA progression, while the investigations have not been fully explained. miR-191-5p upregulation is found in aortic aneurysm. However, its role in AAA has not been addressed. This research purposed to excavate the possible and associated molecular axis of miR-191-5p in AAA. In our study, miR-191-5p level was detected to be high in the tissues from AAA patients in comparison with the control group. After miR-191-5p expression was enhanced, cell viability was repressed, cell apoptosis was boosted, and ECM disruption and the inflammation response were fortified. Furthermore, the relationship among MIR503HG, miR-191-5p, and phospholipase C delta 1 (PLCD1) in VSMCs was disclosed via mechanism assays. Decreased MIR503HG lacked the inhibition on miR-191-5p targeting PLCD1, resulting in downregulation of PLCD1, which facilitated the progression of AAA. Thus, targeting MIR503HG/miR-191-5p/PLCD1 pathway will provide an additional method for the cure of AAA patients.

Glucagon-Like Peptide-1 Inhibits the Progression of Abdominal Aortic Aneurysm in Mice: The Earlier, the Better

OBJECTIVES

Glucagon-like peptide-1 (GLP-1) has a cardiovascular protective effect by preventing abdominal aortic aneurysm (AAA) formation. However, it is unclear at what point the agent should be administered to achieve the optimal effect. In this study, we aimed to determine whether administering the GLP-1 receptor agonist liraglutide during the earlier stages would more efficiently inhibit AAA progression in mice.

METHODS

Depending on the group, mice were given a daily dose of 300 μg/kg liraglutide for 28 days at 7, 14, and 28 days after aneurysm induction. The morphology of the abdominal aorta was monitored using 7.0 T magnetic resonance imaging (MRI) during the administration of liraglutide. After 28 days of administration, the AAA dilatation ratio was calculated, and histopathological examination was performed. Oxidative stress levels were evaluated by the expression of malondialdehyde (MDA) and matrix metalloproteinases (MMPs). The inflammatory response was also evaluated.

RESULTS

Liraglutide treatment led to a decrease in AAA formation, including a reduction in abdominal aorta expansion, elastin degradation in the elastic laminae, and vascular inflammation caused by leukocyte infiltration. The expression of MDA and the activity of MMPs (MMP-2, MMP-9) also decreased. Notably, administering liraglutide during the early stages resulted in a significant reduction in the dilatation rate of the aortic wall, as well as in MDA expression, leukocyte infiltration, and MMP activity in the vascular wall.

CONCLUSIONS

The GLP-1 receptor agonist liraglutide was found to inhibit AAA progression in mice by exerting anti-inflammatory and antioxidant effects, particularly during the early stages of AAA formation. Therefore, liraglutide may represent a potential pharmacological target for the treatment of AAA.

Tributyrin Intake Attenuates Angiotensin II-Induced Abdominal Aortic Aneurysm in LDLR-/- Mice

Abdominal aortic aneurysm (AAA) is a multifactorial cardiovascular disease with a high risk of death, and it occurs in the infrarenal aorta with vascular dilatation. High blood pressure acts on the aortic wall, resulting in rupture and causing life-threatening intra-abdominal hemorrhage. Vascular smooth muscle cell (VSMC) dysregulation and extracellular matrix (ECM) degradation, especially elastin breaks, contribute to structural changes in the aortic wall. The pathogenesis of AAA includes the occurrence of oxidative stress, inflammatory cell infiltration, elastic fiber fragmentation, VSMC apoptosis, and phenotypic transformation. Tributyrin (TB) is decomposed by intestinal lipase and has a function similar to that of butyrate. Whether TB has a protective effect against AAA remains uncertain. In the present study, we established an AAA murine model by angiotensin II (AngII) induction in low-density lipoprotein receptor knockout (LDLR^-/-) mice and investigated the effects of orally administered TB on the AAA size, ratio of macrophage infiltration, levels of matrix metalloproteinase (MMP) expression, and epigenetic regulation. TB attenuates AngII-induced AAA size and decreases elastin fragmentation, macrophage infiltration, and MMP expression in the medial layer of the aorta and reduces the levels of SBP (systolic blood pressure, p < 0.001) and MMP-2 (p < 0.02) in the serum. TB reduces the AngII-stimulated expression levels of MMP2 (p < 0.05), MMP9 (p < 0.05), MMP12, and MMP14 in human aortic smooth muscle cells (HASMCs). Moreover, TB and valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, suppress AngII receptor type 1 (AT1R, p < 0.05) activation and increase the expression of acetyl histone H3 by HDAC activity inhibition (p < 0.05). Our findings suggest that TB exerts its protective effect by suppressing the activation of HDAC to attenuate the AngII-induced AT1R signaling cascade.

Histopathological Characterization of Abdominal Aortic Aneurysms from Patients with Multiple Aneurysms Compared to Patients with a Single Abdominal Aortic Aneurysm

The aim of this study was to investigate histopathological differences in abdominal aortic aneurysms (AAAs) between patients with multiple and single arterial aneurysms, as we suspect that there are different underlying mechanisms in aneurysm formation. Analysis was based on a previous retrospective study on patients with multiple arterial aneurysms (mult-AA; defined as at least four, n = 143) and a single AAA (sing-AAA, n = 972) who were admitted to our hospital for treatment between 2006 and 2016. Available paraffin-embedded AAA wall specimens were derived from the Vascular Biomaterial Bank Heidelberg (mult-AA, n = 12 vs. sing-AAA, n = 19). Sections were analyzed regarding structural damage of the fibrous connective tissue and inflammatory cell infiltration. Alterations to the collagen and elastin constitution were assessed by Masson-Goldner trichrome and Elastica van Gieson staining. Inflammatory cell infiltration, response and transformation were assessed by CD45 and IL-1β immunohistochemistry and von Kossa staining. The extent of aneurysmal wall alterations was assessed by semiquantitative gradings and was compared between the groups using Fisher's exact test. IL-1β was significantly more present in the tunica media in mult-AA compared to sing-AAA (p = 0.022). The increased expression of IL-1β in mult-AA compared to sing-AAA indicates inflammatory processes play a role in aneurysm formation in patients with multiple arterial aneurysms.

Taxifolin ameliorates abdominal aortic aneurysm by preventing inflammation and apoptosis and extracellular matrix degradation via inactivating TLR4/NF-κB axis

BACKGROUND

Abdominal aortic aneurysm (AAA) is a serious aortic disease with high mortality. Vascular smooth muscle cells (VSMCs) loss is a prominent feature of AAA. Taxifolin (TXL) is a natural antioxidant polyphenol and possesses therapeutic functions in numerous human diseases. This study aimed to investigate TXL's impact on VSMC phenotype in AAA.

METHODS

In vitro and in vivo of VSMC injury model was induced by angiotensin II (Ang II). The potential function of TXL on AAA was determined using Cell Counting Kit-8, flow cytometry, Western blot, quantitative reverse transcription-PCR, and enzyme-linked immunosorbent assay. Meanwhile, TXL mechanism on AAA was checked by a series of molecular experiments. Also, TXL function on AAA in vivo was further evaluated using hematoxylin-eosin staining, TUNEL assay, Picric acid-Sirius red staining and immunofluorescence assay in C57BL/6 mice.

RESULTS

TXL alleviated Ang II-induced VSMC injury mainly by enhancing VSMC proliferation and weakening cell apoptosis, alleviating VSMC inflammation, and reducing extracellular matrix (ECM) degradation of VSMCs. Furthermore, mechanistic studies corroborated that TXL reversed the high levels of Toll-like receptor 4 (TLR4) and p-p65/p65 induced by Ang II. Also, TXL facilitated VSMC proliferation and reduced cell apoptosis, repressed inflammation, and ECM degradation of VSMCs, while these effects were reversed by TLR4 overexpression. In vivo studies further confirmed that TXL owned the function of alleviating AAA, such as alleviating collagen fiber hyperplasia and inflammatory cell infiltration in AAA mice, and repressing inflammation and ECM degradation.

CONCLUSION

TXL protected VSMCs against Ang II-induced injury through activating TLR4/noncanonical nuclear factor-kappaB(NF-κB).

Unpacking the Complexities of a Silent Killer

An abdominal aortic aneurysm (AAA) is a life-threatening condition that affects millions of people worldwide [...].

Purinergic receptor P2 × 7 contributes to abdominal aortic aneurysm development via modulating macrophage pyroptosis and inflammation

The purinergic receptor P2 × 7 has been established as an important mediator of inflammation and participates in a variety of cardiovascular diseases including atherosclerosis, however, its role in abdominal aortic aneurysms (AAA) remains unclear. In this study, we demonstrate that P2 × 7 plays essential roles in AAA development via modulating macrophage pyroptosis and inflammation. P2 × 7 is highly expressed in human AAA specimen, as well as in experimental murine AAA lesions (both CaCl₂-and Angiotensin Ⅱ-induced AAA models), and it mainly confines in macrophages. Furthermore, P2 × 7 deficiency or pharmacological inhibition with its antagonist could significantly attenuate aneurysm formation in experimental murine AAA models, while P2 × 7 agonist could promote AAA development. The caspase-I activity, matrix metalloproteinase (MMP) activity, reactive oxygen species (ROS) production and pro-inflammatory gene expression were significant reduced in experimental AAA lesions in mice with P2 × 7 deficiency or inhibition. Mechanistically, macrophage P2 × 7 can mediate the activation of NLRP3 inflammasome and activate its downstream caspase-1 to initiate the pyroptosis pathway. After caspase-1 activation, it further cleaves pro-interleukin (IL)-1β and gasdermin D (GSDMD). Consequently, the N-terminal fragment of GSDMD forms pores on the cell membrane, leading to macrophage pyroptosis and release of the pro-inflammatory factor IL-1β. The resulting vascular inflammation further leads to the upregulation of MMP and ROS, thereby promoting AAA development. In summary, these data identify P2 × 7-mediated macrophage pyroptosis signaling pathway as a novel contributory mechanism of AAA formation.

The role of long non-coding RNA in abdominal aortic aneurysm

The abdominal aortic aneurysm (AAA) is characterized by segmental expansion of the abdominal aorta and a high mortality rate. The characteristics of AAA suggest that apoptosis of smooth muscle cells, the production of reactive oxygen species, and inflammation are potential pathways for the formation and development of AAA. Long non-coding RNA (lncRNA) is becoming a new and essential regulator of gene expression. Researchers and physicians are focusing on these lncRNAs to use them as clinical biomarkers and new treatment targets for AAAs. LncRNA studies are beginning to emerge, suggesting that they may play a significant but yet unidentified role in vascular physiology and disease. This review examines the role of lncRNA and their target genes in AAA to increase our understanding of the disease’s onset and progression, which is crucial for developing potential AAA therapies.

Group 2 Innate Lymphoid Cells Protect Mice from Abdominal Aortic Aneurysm Formation via IL5 and Eosinophils

Development of abdominal aortic aneurysms (AAA) enhances lesion group-2 innate lymphoid cell (ILC2) accumulation and blood IL5. ILC2 deficiency in Rora^fl/fl Il7r^Cre/+ mice or induced ILC2 depletion in Icos^fl-DTR-fl/+ Cd4^Cre/+ mice expedites AAA growth, increases lesion inflammation, but leads to systemic IL5 and eosinophil (EOS) deficiency. Mechanistic studies show that ILC2 protect mice from AAA formation via IL5 and EOS. IL5 or ILC2 from wild-type (WT) mice, but not ILC2 from Il5^-/- mice induces EOS differentiation in bone-marrow cells from Rora^fl/fl Il7r^Cre/+ mice. IL5, IL13, and EOS or ILC2 from WT mice, but not ILC2 from Il5^-/- and Il13^-/- mice block SMC apoptosis and promote SMC proliferation. EOS but not ILC2 from WT or Il5^-/- mice block endothelial cell (EC) adhesion molecule expression, angiogenesis, dendritic cell differentiation, and Ly6C^hi monocyte polarization. Reconstitution of WT EOS and ILC2 but not Il5^-/- ILC2 slows AAA growth in Rora^fl/fl Il7r^Cre/+ mice by increasing systemic EOS. Besides regulating SMC pathobiology, ILC2 play an indirect role in AAA protection via the IL5 and EOS mechanism.

ADAR1 Non-Editing Function in Macrophage Activation and Abdominal Aortic Aneurysm

BACKGROUND

Macrophage activation plays a critical role in abdominal aortic aneurysm (AAA) development. However, molecular mechanisms controlling macrophage activation and vascular inflammation in AAA remain largely unknown. The objective of the study was to identify novel mechanisms underlying adenosine deaminase acting on RNA (ADAR1) function in macrophage activation and AAA formation.

METHODS

Aortic transplantation was conducted to determine the importance of nonvascular ADAR1 in AAA development/dissection. Ang II (Angiotensin II) infusion of ApoE-/- mouse model combined with macrophage-specific knockout of ADAR1 was used to study ADAR1 macrophage-specific role in AAA formation/dissection. The relevance of macrophage ADAR1 to human AAA was examined using human aneurysm specimens. Moreover, a novel humanized AAA model was established to test the role of human macrophages in aneurysm formation in human arteries.

RESULTS

Allograft transplantation of wild-type abdominal aortas to ADAR1+/- recipient mice significantly attenuated AAA formation, suggesting that nonvascular ADAR1 is essential for AAA development. ADAR1 deficiency in hematopoietic cells decreased the prevalence and severity of AAA while inhibited macrophage infiltration and aorta wall inflammation. ADAR1 deletion blocked the classic macrophage activation, diminished NF-κB (nuclear factor kappa B) signaling, and enhanced the expression of a number of anti-inflammatory microRNAs. Mechanistically, ADAR1 interacted with Drosha to promote its degradation, which attenuated Drosha-DGCR8 (DiGeorge syndrome critical region 8) interaction, and consequently inhibited pri- to pre-microRNA processing of microRNAs targeting IKKβ, resulting in an increased IKKβ (inhibitor of nuclear factor kappa-B) expression and enhanced NF-κB signaling. Significantly, ADAR1 was induced in macrophages and interacted with Drosha in human AAA lesions. Reconstitution of ADAR1-deficient, but not the wild type, human monocytes to immunodeficient mice blocked the aneurysm formation in transplanted human arteries.

CONCLUSIONS

Macrophage ADAR1 promotes aneurysm formation in both mouse and human arteries through a novel mechanism, that is, Drosha protein degradation, which inhibits the processing of microRNAs targeting NF-kB signaling and thus elicits macrophage-mediated vascular inflammation in AAA.