Immune and inflammatory mechanisms of abdominal aortic aneurysm

IRF8 Drives Conventional Type 1 Dendritic Cell Differentiation and CD8+ T Cell Activation to Aggravate Abdominal Aortic Aneurysm Development

Abdominal aortic aneurysm (AAA) is the most common true aneurysm worldwide, and recent studies suggest that dendritic cells (DCs) play a key role in its development, though the specific subtypes and underlying mechanisms remain unclear. In this study, the role of interferon regulatory factor 8 (IRF8) in AAA is investigated by focusing on its effect on the differentiation of DC precursors into conventional type 1 dendritic cells (cDC1s). It is found significant infiltration of HLA-DR+ IRF8+ cells in human AAA tissue samples. In mice, DC-specific overexpression of Irf8 exacerbates aneurysm expansion following periadventitial elastase application, while DC-specific Irf8 deletion attenuates AAA development. Batf3-/- mice, which lack cDC1s, exhibit AAA characteristics similar to the Irf8-deleted mice. Additionally, an increased population of activated CD8+ T cells is observed in the DC-Irf8 overexpressed mice, while the DC-Irf8 deletion mice show a decrease in these cells. Blocking antigen cross-presentation to CD8+ T cells also reduces AAA progression. Tissue microarray analysis of human aortic samples further confirms a correlation between IRF8 expression and AAA development. These findings suggest that IRF8 activation promotes cDC1 differentiation, leading to the recruitment of CD8+ T cells, which contribute to aortic wall destruction and AAA formation.

Vascular architecture-on-chip: engineering complex blood vessels for reproducing physiological and heterogeneous hemodynamics and endothelial function

Human circulation exhibits significant diversity and heterogeneity of blood vessel shapes. The complex architecture of these vessels may be physiological or pathological resulting in unique hemodynamics and endothelial cell phenotypes that may determine the regulation and alteration of cell signaling pathways and vascular function. While human microphysiological systems of blood vessels (vessel-chips) have mimicked several aspects of vascular pathophysiology, engineering of these tools is still limited to the fabrication of homogeneous tubular structures, especially when living endothelial cell culture is also included. Here, a common unifying approach based on gravitational lumen patterning (GLP) is presented to create non-uniform, living 3D and closed vascular lumens embedded in a collagen matrix and lined with endothelial cells, resulting in reproduction of the architecture of straight vessels, stenosis, bifurcations, aneurysms and tortuous vessels. Upon blood perfusion, these systems reveal the nature of altered flow dynamics and corresponding endothelial cell morphology. These vessel-chips closely mimic the structural variations and resulting endothelial responses often observed in vivo and may be used to investigate vascular complications like aortic and cerebral aneurysm, arterial tortuosity syndrome, atherosclerosis, carotid artery disease, etc., where architecture plays a crucial role in disease onset and progression.

AKAP1-STABILIZED TIMP-4 ATTENUATES ANG-II-INDUCED OXIDATIVE STRESS AND INFLAMMATION IN VASCULAR SMOOTH MUSCLE CELLS BY INACTIVATING THE NF-ΚB SIGNALING

ABSTRACT

Background: Oxidative stress and inflammation are key factors contributing to the complex pathogenesis of abdominal aortic aneurysm (AAA). Tissue inhibitor of metalloproteinases-4 (TIMP-4) expression is reduced in AAA patients. In this study, we investigated the impact of TIMP-4 on the phenotype alterations induced by angiotensin II (Ang-II) in human vascular smooth muscle cells (VSMCs). Methods: The expression profiling of TIMP-4 and A-kinase anchoring protein (AKAP1) in AAA samples was analyzed using the GSE7084 and GSE140947 datasets. Levels of TIMP-4 and AKAP1 in Ang-II-exposed VSMCs and AAA tissues and serum samples were detected. RNA immunoprecipitation (RIP) experiment and mRNA stability analysis were used to examine the interaction between AKAP1 and TIMP-4 mRNA. The impact of the AKAP1/TIMP-4 cascade on Ang-II-induced VSMC phenotype alterations was determined by evaluating cell viability, apoptosis, oxidative stress, and inflammation. Results: TIMP-4 and AKAP1 levels were decreased in Ang-II-exposed VSMCs. Increased TIMP-4 expression protected VSMCs against Ang-II-evoked growth impairment in vitro . Moreover, TIMP-4 upregulation diminished Ang-II-evoked oxidative stress and inflammation in VSMCs. Mechanistically, RNA binding protein (RBP) AKAP1 stabilized TIMP-4 mRNA to elevate TIMP-4 expression. TIMP-4 reduction partially abrogated AKAP1-driven suppression on oxidative stress, inflammation, matrix metalloproteinase (MMP9) expression, and nuclear factor kappa B (NF-κB) pathway activation in Ang-II-exposed VSMCs. Additionally, TIMP-4 and AKAP1 levels were downregulated in AAA patients in their AAA tissues and serum samples. TIMP-4 and AKAP1 had good diagnostic values for AAA with high area under the ROC curve. Conclusion: Our study provides evidence for the role of the AKAP1/TIMP-4/NF-κB pathway in Ang-II-induced VSMC inflammation and oxidative stress.

Factors Influencing Early Diagnosis of Ruptured Abdominal Aortic Aneurysms: The Role of Neutrophils

Background

Currently, there is no effective and convenient indicator for the early differential diagnosis of ruptured abdominal aortic aneurysms (rAAAs) from unruptured abdominal aortic aneurysms (AAAs).

Objective

The aim of this study was to explore indicators for the early differential diagnosis of rAAAs in a clinical setting.

Methods

This case‒control study included 276 subjects within the last 5 years (220 patients with unruptured AAAs; 56 patients with rAAAs) in the initial analysis and 229 subjects (186 patients with unruptured AAA's; 43 patients with rAAA's) after subgroup analysis. The meaningful indicators were screened via univariate analysis and logistic regression analysis. The diagnostic performance and clinical usefulness of the indicators were assessed and compared using receiver operating characteristic (ROC) curve analysis, decision curve analysis (DCA) and clinical impact curve (CIC).

Results

A high venous blood neutrophil counts (OR = 1.316, P = 0.007) was found to be a risk factor for rAAAs in the initial model. After subgroup analysis, the levels of neutrophils (OR = 1.394, P = 0.017) and D-dimer (OR = 1.023, P = 0.043) were both significantly greater in patients with a rAAA. Abdominal pain (OR = 32.613, P = 0.044) and back pain (OR=91.946, P = 0.036) were strongly associated with the rupture of AAA. The results of the receiver operating characteristic (ROC) analysis revealed that neutrophils (AUC: 0.847, 95% CI: 0.774-0.921) and NLR (AUC: 0.795, 95% CI: 0.717-0.873) had good diagnostic performance for rAAA. DCA demonstrated that the net benefit of neutrophils was greater than that of other indicators. The CIC confirmed that the model has good clinical usefulness.

Conclusion

The use of neutrophils may enhance the early diagnostic accuracy for identifying rAAAs and holds potential for clinical and scientific applications.

Identification of a Gene Expression Signature to Predict the Risk of Abdominal Aortic Aneurysm in Psoriasis Patients

Background 

Psoriasis is an immune-mediated, hereditary condition that presents itself in the skin or joints, or even both. Increasing evidence indicates that psoriasis is connected to an elevated risk of abdominal aortic aneurysm (AAA), owing to their shared inflammatory pathogenesis. Nevertheless, the interplay between psoriasis and AAA lacks sufficient documentation.

Methods

 Through WGCNA and DEGs, psoriasis and AAA phenotype-related genes were identified. Identifying risk genes involved in both psoriasis and AAA involved generating candidate genes by finding the common intersection of hub genes, followed by using LASSO regression. Following this, a nomogram was created to forecast the development of psoriasis alongside AAA, and was then assessed through a ROC curve, DCA, calibration curve, and PR curve. Five algorithms, namely CIBERSORT, ssGSEA, ESTIMATE, MCPcounter, and QuanTIseq, were utilized to assess immune infiltration differences between high and low-risk groups. Simultaneously, we verified the differential gene expression in different tissues.

Results

A total of 1073 psoriasis hub genes and 128 AAA hub genes were generated. A Venn diagram revealed 20 candidate genes that were common to both hub genes of psoriasis and AAA. Of these, six genes (CCR7, CD3D, GBP5, HCLS1, IL7R, and ITGAL) were identified as risk genes. The gene signature generated by these genes demonstrated high accuracy in predicting psoriasis and AAA. Using five algorithms for immune infiltration analysis, an abundance of inflammatory cells was observed in high-risk subgroups. The above six genes were found to be highly expressed in both psoriasis tissue and abdominal aortic aneurysm tissue.

Conclusions 

The study resulted in the identification of a novel gene signature, including six high-risk genes, that has enhanced our knowledge of the common causes and control mechanisms of psoriasis and AAA. These findings are anticipated to pave the way for promising therapeutic targets in mitigating the comorbidities of cardiovascular disease.

Deficiency of IL-7R attenuates abdominal aortic aneurysms in mice by inhibiting macrophage polarization towards M1 phenotype through the NF-κB pathway

BACKGROUND

Abdominal aortic aneurysm (AAA) is a common degenerative disease of the abdominal aorta, which can result in extremely high mortality owing to the rupture of the abdominal aorta. The activation of IL-7R has been shown to modulate the inflammatory responses, which play an important role in the progression of AAAs. However, the mechanism of IL-7/IL-7R axis in AAAs is still unclear.

AIMS

This study aims to investigate the effects of IL-7R on AAAs and the underlying mechanisms involved.

METHODS

Wild-type C57BL/6 and IL-7R knockout mice were used as experimental subjects. ELISA analysis, histological staining, western blotting and qPCR were performed to explore effects of IL-7R deficiency in the formation and development of elastase-induced AAAs. Transwell, CCK8, and immunofluorescence assays detected the migration and polarization of RAW264.7 macrophages in vitro.

RESULT

We demonstrated that IL-7R was elevated in mice with AAAs. Blocking IL-7R can inhibit the formation of AAAs and reduce aortic dilatation, elastic layer degradation, and inflammatory cell infiltration. Knockout of IL-7R suppressed the migration, infiltration and M1 polarization of macrophages. Moreover, inhibition of the NF-κB signaling pathway by BAY 11-7082 attenuated the macrophage-mediated inflammatory responses caused by IL-7R overexpression.

CONCLUSION

In short, this study showed that IL-7R promotes the infiltration and migration of macrophages by regulating M1 macrophage polarization, possibly in part via activation of the NF-κB pathway, which may be associated with the development of AAAs.

Glycated hemoglobin levels and abdominal aortic aneurysm incidence in primary prevention populations

OBJECTIVE

Abdominal aortic aneurysm (AAA) is a life-threatening condition characterized by the pathological dilation of the abdominal aorta. Diabetes mellitus is a well-established risk factor for cardiovascular diseases, yet its relationship with AAA remains debated. We aimed to identify longitudinal associations between glycated hemoglobin A1c (HbA1c) level and the risk of AAA development.

METHODS

A prospective cohort study was conducted using UK Biobank data, encompassing 326,152 participants aged 39 to 73 years, recruited from 2006 to 2010. Participants provided biological samples and completed questionnaires. AAA cases was identified via International Classification of Diseases, 10th edition, codes from linked health records. HbA1c levels and other covariates were measured. Logistic and Cox regression models were used to assess the associations between HbA1c levels and AAA prevalence and incidence. Restricted cubic spline models were applied to examine dose-response relationships. Subgroup, interaction, and sensitivity analyses were also performed.

RESULTS

The study revealed a nonlinear inverted U-shaped HbA1c-AAA risk relationship, with hazard ratios for AAA incidence peaking at 5.82% before declining. Compared with the lowest quartile of HbA1c levels, ascending quartiles showed progressively elevated AAA risks: Q2 = 1.14 (95% confidence interval [CI], 1.01-1.29), Q3 = 1.11 (95% CI, 0.98-1.26), Q4 = 1.27 (95% CI, 1.12-1.44; all P for trend < .05). Stratified analyses identified amplified risk escalation in younger age, elevated low-density lipoprotein cholesterol, and nondiabetic subgroups. Sensitivity analyses confirmed association robustness. Notably, younger participants (<65 years) exhibited 2.38-fold higher Q4/Q1 AAA risk (95% CI, 1.89-2.99).

CONCLUSIONS

This study reveals a bidirectional HbA1c-AAA incidence association, underscoring the clinical imperative for optimized glycemic control in primary AAA prevention, particularly among younger adults and hyperlipidemic patients.

Abdominal Aortic Aneurysm and Liver Fibrosis: Clinical Evidence and Molecular Pathomechanisms

To stimulate further research, this review summarizes studies linking liver fibrosis with the risk of abdominal aortic aneurysms (AAA). AAA is defined as a permanently weakened and dilated abdominal aorta, which develops due to inflammation of the tunica media, activation of the renin-angiotensin-aldosterone system, immune system activation, and coagulation disorders. Typically asymptomatic, AAA is often incidentally detected through imaging done for abdominal symptoms or as part of screening programs. AAA follows a variable course and has a mortality rate strongly dependent on age and sex. Risk factors for AAA include age, male sex, ethnicity, family history of AAA, lifestyle habits, arterial hypertension, dyslipidemia, and comorbid atherosclerotic cardiovascular disease. Conversely, individuals with type 2 diabetes, female sex, and certain ethnicities are at a reduced risk of AAA. Liver fibrosis, resulting from chronic liver diseases owing to varying etiologies, is increasingly recognized as a potential contributor to AAA development. Evidence increasingly indicates that metabolic dysfunction-associated steatotic liver disease (MASLD) and other chronic liver conditions may intensify inflammatory pathways shared with AAA, thereby potentially exacerbating AAA progression. This review specifically examines the epidemiology and risk factors associated with the link between AAA and liver fibrosis. It also highlights potential pathomechanisms, including systemic inflammation, oxidative stress, and extracellular matrix remodeling, which may contribute to both conditions. Although these findings underscore significant overlaps in risk profiles, additional research is needed to clarify whether type 2 diabetes, female sex, and certain ethnicities truly confer protection against AAA or if this association is influenced by other confounding variables. Ultimately, addressing these open questions will help guide targeted therapeutic interventions and the identification of novel biomarkers to predict disease progression.

The Molecular Mechanisms of Bergapten Against Abdominal Aortic Aneurysm: Evidence From Network Pharmacology, Molecular Docking/Dynamics, and Experimental Validation

This study endeavors to assess the potential protective role of bergapten (BP) in mitigating abdominal aortic aneurysm (AAA) and to decipher the underlying mechanisms and molecular targets. Network pharmacology was utilized to search for potential targets of BP against AAA. Molecular docking and molecular dynamics simulations were utilized to validate the interaction of BP with core targets, and then the therapeutic effect and mechanism of BP on AAA were verified by using an elastase-induced AAA model. Network pharmacology analysis identified five pharmacological targets for BP, including EGFR, SRC, PIK3CA, PIK3CB, and JAK2. Molecular docking and molecular dynamics simulations further prioritized JAK2 as the most promising candidate for the potential treatment of AAA. The results of animal experiments demonstrated that BP significantly reduced the expression of inflammatory cytokines IL-6, TNF-α, and IL-1β in the aortic tissue of AAA mouse model, and inhibited the phosphorylation of JAK2 and STAT3. BP plays an important role in the treatment of AAA, and it may become a promising drug to combat AAA progression. The inhibitory effect of BP on AAA vascular progression and the attenuation of inflammatory cell infiltration may be related to the regulation of JAK2/STAT3 signaling pathway.

Causal Characteristics of Immune Cells Associated with Aortic Dissection: A Mendelian Randomisation Analysis

Background

This study investigates the causal relationships between 731 immune cell traits and aortic dissection (AD) using Mendelian randomisation (MR). By identifying specific immune cell phenotypes contributing to AD, we explore their clinical implications for risk stratification and therapeutic interventions.

Methods

A bivariate MR framework analysed the causal dynamics between immune cell attributes and AD, using genetic variants as instrumental variables. Summary statistics from a genome-wide association study for 731 immune phenotypes were obtained. Univariable MR analysis was conducted using the inverse-variance weighted method supplemented by sensitivity analyses. Horizontal pleiotropy was assessed using MR-Egger and MR pleiotropy residual sum and outlier. Significant cis-expression quantitative trait loci (eQTL) were identified via the Genotype-Tissue Expression (GTEx) database, followed by tissue-specific expression and pathway analyses.

Results

Four immunophenotypes exhibited positive causal effects on AD, while one showed a negative effect. Pathogenic traits included the median fluorescence intensity of CD19 on transitional B cells, immunoglobulin D- CD38dim B cells, CD3 on CD39+ CD4+ Treg cells, and CD3 on CD39+ activated Treg cells. The protective trait was the absolute count of CD86+ myeloid dendritic cells. Sensitivity analyses validated these associations. Pathway enrichment analysis highlighted significant arterial enrichments and key biological processes, identifying SLAMF6 and CD28 as key genes.

Conclusion

This study suggests potential causal roles for specific immune cell traits in AD pathogenesis, although these findings should be interpreted with caution due to study limitations. The identified immune cell types and associated eQTL genes offer promising targets for clinical risk stratification and therapeutic interventions. Future research should focus on translating these findings into practical strategies for patient care.

Identifying nexilin as a central gene in neutrophil-driven abdominal aortic aneurysm pathogenesis

OBJECTIVES

Abdominal aortic aneurysm (AAA) is an inflammation-driven disease in which neutrophil infiltration is critical to its progression. This study aims to explore the molecular mechanisms behind neutrophil infiltration in AAA and identify key regulatory genes.

METHODS

We utilized weighted gene co-expression network analysis (WGCNA) and differential gene expression analysis to compare AAA and healthy abdominal aortic tissues. Functional enrichment analysis and a protein-protein interaction (PPI) network were constructed to understand gene functions. Machine learning algorithms were applied to identify key hub genes, followed by in vivo validation using an ApoE-/- mouse model.

RESULTS

Neutrophils, NK cells, and pDCs were significantly increased in AAA tissues. WGCNA identified 234 genes associated with neutrophil infiltration, of which 39 were significantly differentially expressed. Functional enrichment analysis highlighted roles in actin-related processes and pathways. Nexilin (NEXN) was consistently identified as a key hub gene negatively correlated with immune cell infiltration. In vivo validation confirmed that NEXN inhibits AAA progression in ApoE-/- mice by regulating immune cell infiltration.

CONCLUSION

NEXN plays a crucial role in modulating neutrophil infiltration in AAA. These findings provide new molecular insights into AAA pathogenesis and suggest NEXN as a potential target for AAA therapy.

Causal relationship between mental disorders and abdominal aortic aneurysm: Insights from the genetic perspective

BACKGROUND

This study aims to investigate the genetic link between mental disorders-depression, schizophrenia (SCZ), and bipolar disorder (BIP)-and abdominal aortic aneurysm (AAA).

METHODS

We first examined the genetic associations between AAA and mental disorders by analyzing global and local genetic correlations as well as shared genomic loci. Global genetic correlation was assessed using linkage disequilibrium score regression (LDSC) and the GeNetic cOVariance Analyzer (GNOVA), while local genetic correlation was analyzed using the SUPERGNOVA approach. To identify shared genetic variants, the pleiotropy-informed conditional and conjunctional false discovery rate (pleioFDR) method was applied. Subsequently, the univariate Mendelian Randomization (UMR) was employed to evaluate the causal relationship, complemented by multivariate MR (MVMR) to account for potential confounding biases. Additionally, mediation analysis was performed to determine whether known risk factors mediate the identified causal relationships.

RESULTS

Global correlations showed positive links between depression, SCZ, and AAA, but not BIP. Local analyses identified specific genomic regions of correlation. We found 26, 141, and 10 shared loci for AAA with depression, SCZ, and BIP, respectively. UMR indicated significant associations between genetically predicted depression (OR 1.270; 95 % CI 1.071-1.504; p = 0.006) and SCZ (OR 1.047; 95 % CI 1.010-1.084; p = 0.011) with AAA, but not BIP. These results were confirmed by MVMR analyses. Mediation analyses showed that smoking, hypertension, hyperlipidemia, and coronary atherosclerosis mediated the impact of depression on AAA while smoking mediated SCZ's impact.

CONCLUSION

This study provides evidence that genetically predicted depression and SCZ are linked to an increased risk of AAA, mediated by traditional AAA risk factors.

Unraveling Novel Subsets of Lymphocytes Involved in Sac Expansion in the Tertiary Lymphoid Structure Within an Abdominal Aortic Aneurysm

BACKGROUND

Chronic inflammation is involved in the development of abdominal aortic aneurysm (AAA). A tertiary lymphoid structure (TLS) within vascular lesions has recently been focused on for its role in modulation of inflammation in local tissues. We aimed to elucidate the relationships between TLS and pathophysiology of AAA.

METHODS

Abdominal aortic samples obtained from 37 patients with AAA (men/women: 34/3, age: 72.8±9.9 years) and 15 autopsied patients who died from non-aortic events (men/women: 11/4, age: 65.5±9.8 years) were investigated.

RESULTS

TLSs in AAA lesions were confirmed by focal infiltration of CD3-positive cells surrounding germinal center-like structures containing CD20-positive cells between the tunica adventitia and tunica media layers. The formation of a TLS was significantly more prevalent in AAA patients than in autopsied patients. The number of TLSs in AAA lesions was positively correlated with sac diameter (r=0.357, P=0.035) and the amount of intraluminal thrombosis (r=0.466, P=0.005). T cells and B cells were predominant cellular populations among CD45+ cells in AAA lesions. There was a significantly positive correlation between the proportions of interfollicular T follicular helper (CD3+CD4+CD45RA-CXCR5+PD-1+) cells and double negative B (CD3-CD19+IgD-CD27-) cells, and they were positively correlated with sac diameter, intraluminal thrombosis, and serum lipids. Deposited single-cell RNA-sequencing data for AAA showed that T follicular helper cells and double negative B cells were associated with lipid metabolism, T cell activation/proliferation and inflammation.

CONCLUSIONS

The formation of a TLS in AAA lesions is associated with sac diameter and intraluminal thrombosis in connection with interfollicular T follicular helper cells and double negative B cells, which may contribute to the pathophysiology of AAA and might be novel therapeutic targets for the development of AAA.

Chemokine Receptor 2 Is a Theranostic Biomarker for Abdominal Aortic Aneurysms

Abdominal aortic aneurysm (AAA) is a degenerative vascular disease with a high mortality upon rupture. There is no diagnosis to predict the rupture nor effective medical therapies to prevent rupture. Here we demonstrate that the C-C chemokine receptor type 2 (CCR2) is a theranostic biomarker for AAA. In rat AAA models, we determined the potential of a CCR2-targeted positron emission tomography radiotracer [64Cu]Cu-DOTA-ECL1i predicting AAA rupture. Using a CCR2 inhibitor, we observed the effective prevention of rupture in AAA rat models. In humans, CCR2 positron emission tomography showed intense radiotracer uptake along the AAA wall in patients while little signal was observed in healthy volunteers.

Remnant cholesterol and risk of aortic aneurysm and dissection: a prospective cohort Study from the UK biobank study and mendelian randomization analysis

AIM

This study aimed to examine the relationships between remnant cholesterol (RC) and the risk of aortic aneurysm and dissection (AAD).

METHODS

This prospective cohort study included 368,139 European adults from the UK Biobank. Additionally, the causal relationship between RC and AAD was investigated using Mendelian randomization (MR) analyses.

RESULTS

During a median follow-up of 13.65 years, 1,634 cases of abdominal aortic aneurysm (AAA), 698 cases of thoracic aortic aneurysm (TAA), and 184 cases of aortic dissection (AD) were identified. Elevated RC levels were associated with an increased risk of AAA compared to the reference group ([highest vs. lowest RC levels]: adjusted hazard ratio (HR) = 1.65, 95% CI: 1.36-1.99). However, no significant association was observed between high RC levels and the risk of either TAA or AD. Two-sample MR analyses supported a significant causal effect of RC on AAA risk (odds ratio (OR) = 2.08, 95% CI: 1.70-2.56). The association between RC and AAA persisted after adjusting for the effects of RC-associated genetic variants on low-density lipoprotein cholesterol (LDL-C). In contrast, MR analyses did not indicate any causal associations between RC and TAA or AD.

CONCLUSIONS

Elevated RC was linked to a greater risk of developing AAA, with MR analyses confirming a causal relationship. These findings suggest that RC may function as a new biomarker for AAA and could be integral to strategies aimed at preventing AAA.

CIDEC/FSP27 exacerbates obesity-related abdominal aortic aneurysm by promoting perivascular adipose tissue inflammation

Abdominal aortic aneurysm (AAA) is strongly correlated with obesity, partially due to the abnormal expansion of abdominal perivascular adipose tissue (PVAT). Cell death-inducing DNA fragmentation factor-like effector C (CIDEC), also known as fat-specific protein 27 (FSP27) in rodents, is specifically expressed in adipose tissue where it mediates lipid droplet fusion and adipose tissue expansion. Whether and how CIDEC/FSP27 plays a role in AAA pathology remains elusive. Here, we show that FSP27 exacerbates obesity and angiotensin Ⅱ (Ang Ⅱ)-induced AAA progression. FSP27 deficiency in mice inhibited high-fat diet-induced PVAT expansion and inflammation. Both global and adipose tissue-specific FSP27 ablation significantly decreased obesity-related AAA incidence. Deficiency of FSP27 in adipocytes abrogated matrix metalloproteinase-12 (MMP12) expression in aortic tissues. Infiltrated macrophages, which partially colocalize with MMP12, were significantly decreased in the FSP27-deficient aorta. Mechanistically, knockdown of Fsp27 in 3T3-L1 adipocytes inhibited C-C motif chemokine ligand 2 (CCL2) expression and secretion through a c-Jun N-terminal kinase (JNK)-dependent pathway, thereby leading to reduced induction of macrophage migration, while Cidec overexpression rescued this effect. Overall, our study demonstrates that CIDEC/FSP27 in adipose tissue contributes to obesity-related AAA formation, at least in part, by enhancing PVAT inflammation and macrophage infiltration, thus shedding light on its significance as a key regulator in the context of obesity-related AAA.

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.

Atractylenolide-I prevents abdominal aortic aneurysm formation through inhibiting inflammation

Background

Abdominal aortic aneurysm (AAA) is a degenerative disease with high mortality. Chronic inflammation plays a vital role in the formation of AAA. Atractylenolide-I (ATL-I) is a major bioactive component of Rhizoma Atractylodis Macrocephalae that exerts anti-inflammatory effects in various diseases. The purpose of this study is to investigate the role of ATL-I in the progression of AAA.

Methods

AAA was constructed in C57BL/6 mice by porcine pancreatic elastase (PPE)-incubation, and the diameter of the aorta was measured by ultrasound. ATL-I was administered by gavage on the second day after modeling to explore its significance in AAA. The pathological and molecular alteration was investigated by immunostaining, ELISA, qRT-PCR and Western blotting.

Results

ATL-I inhibited the dilatation of the abdominal aorta and decreased the incidence of AAA. ATL-I alleviated the infiltration of macrophages in the adventitia and reduced the levels of proinflammatory factor IL-1β and IL-6 in the aorta and circulatory system, while increasing the expression of anti-inflammatory factor IL-10. Moreover, ATL-I restrained loss of smooth muscle cells and elastic fiber degradation by suppressing MMP-2 and MMP-9 expression. Mechanistically, phospho-AMPK expression was elevated in AAA groups, and ATL-I administration suppressed its expression to improve the pathological damage of aorta.

Conclusions

ATL-I meliorated vascular inflammation by targeting AMPK signaling, ultimately inhibiting AAA formation, which provided an alternative agent for AAA treatment.

Prediction of the need for surgery in patients with unruptured abdominal aortic aneurysm based on SOFA score

OBJECTIVE

This retrospective study aimed to explore the association and clinical value of sequential organ failure assessment (SOFA) score on the predictors of adverse events in patients with unruptured abdominal aortic aneurysms (AAA).

METHODS

A total of 322 patients from Medical Information Mart for Intensive Care IV database were enrolled. Logistic regression was conducted to explore the association between SOFA and primary outcome (need for surgery, NFS). Receiver operating characteristic (ROC) and nomogram analyses were used to assess its performance for predicting NFS. We also explored the association and clinical value of SOFA on secondary outcomes including hospital length of stay (LOS), ICU-LOS, and in-hospital mortality by linear and logistic regression analyses, generalized additive model, ROC, and decision curve analysis.

RESULTS

Totally 291 patients underwent the surgery. High SOFA score significantly correlated with NFS both in crude and adjusted models (all P<0.05). SOFA had a relatively favorable prediction performance on NFS (AUC = 0.701, 95%CI: 0.596-0.802). After adjusting for related diseases, its prediction performance was increased. When SOFA was combined with lactate and gender, the model showed an AUC of 0.888 (95%CI: 0.759-1.000) and 0.3-0.9 prediction possibility. Further, the SOFA also showed significant relationship with hospital-LOS, ICU-LOS, and in-hospital mortality (all P<0.05), and exerted some value in the prediction of 7-day hospital-LOS (AUC = 0.637, 95%CI: 0.575-0.686) and in-hospital mortality (AUC = 0.637, 95%CI: 0.680-0.845).

CONCLUSIONS

SOFA score was related to the NFS and can be regarded as a useful indicator for predicting the NFS in patients with AAA.

The Association between Plasma Proinflammatory Cytokine Concentrations and Endoleak after Endovascular Aortic Aneurysm Repair

BACKGROUND

The most common complication after endovascular aortic aneurysm repair (EVAR) is continuous sac perfusion, known as endoleak. Evaluating markers released from the aneurysm wall into circulation has been suggested as a possible alternative for detecting endoleaks. The aim of this study was to examine whether circulating concentrations of different proinflammatory interleukins (IL-1β, IL-2, IL-6, IL-8), monocyte chemoattractant protein-1 (MCP-1), and tumor necrosis factor alpha (TNF-α) were elevated in patients with endoleak after EVAR.

METHODS

A prospective observational study with 100 patients undergoing elective EVAR was conducted. Blood samples were taken before surgery, at 7 days, 6 months, and 12 months after EVAR to quantify the mentioned cytokines using a Bio-Plex assay. Patients were followed up for 12 months to detect endoleak occurrence.

RESULTS

In patients with endoleak, mean concentrations of certain cytokines in plasma differed significantly from those without endoleak: preoperative IL-8 (9.83; P < 0.001), preoperative MCP-1 (75.94; P = 0.003), preoperative TNF-α (5.46; P = 0.05), among others. A binary logistic regression analysis revealed that preoperative IL-8 (P = 0.003), MCP-1 at 7 days postoperative (P = 0.002), and IL-1 at 12 months postoperative were significantly associated with endoleak, with IL-1 being the most influential biomarker (odds ratio = 2.2). A receiver operating characteristic curve showed an area under the curve of 0.7, with cutoff points of 33.4 for preoperative IL-8, 145 for MCP-1 at 7 days postoperative, and 2.3 for IL-1 at 12 months postoperative.

CONCLUSIONS

This study suggests that inflammatory biomarkers such as IL-1, IL-8, MCP-1, and TNF-α have the potential to serve as important adjuncts to conventional imaging techniques in monitoring patients post-EVAR. These biomarkers may help identify individuals at higher risk of developing endoleaks, guiding more focused and timely imaging follow-up. However, their practical applicability requires further investigation.

CXCL8 upregulation mediates inflammatory cell infiltration and accelerates abdominal aortic aneurysm progression

OBJECTIVE

To explore abdominal aortic aneurysm (AAA) pathogenesis and identify early diagnostic markers, providing a theoretical basis for novel preventive and therapeutic strategies.

METHODS

Gene expression profiles were retrieved from the Gene Expression Omnibus database (datasets: GSE7084, GSE47472, and GSE57691) comprising messenger RNA data from the aortic samples of 69 patients with AAA and 25 non-AAA controls. Data were merged and normalized; bioinformatics analysis was conducted on upregulated differentially expressed genes.

RESULTS

C-X-C motif chemokine ligand 8 (CXCL8) was prominently involved in regulating the chemokine signaling pathway. CXCL8 expression was significantly higher in the aortic walls of patients with AAA than that of controls. NLRP3, interleukin (IL)-18, and IL-1β expression levels were upregulated in patients with AAA and positively correlated with CXCL8 expression. CXCL8 may directly or indirectly interact with NLRP3.

CONCLUSIONS

CXCL8 was upregulated in patients with AAA and induced inflammatory cell infiltration and cytokine secretion. CXCL8-induced NLRP3 inflammasome regulation triggered pyroptosis in vascular smooth muscle cells, exacerbating inflammation and tissue damage in the aortic wall. This degeneration of the aortic media accelerated AAA progression.

Intervention effect of regulating GABA-A receptor activity on the formation of experimental abdominal aortic aneurysm in rats

Abdominal aortic aneurysm is a potentially fatal vascular inflammatory disease characterized by infiltration of various inflammatory cells.The GABA-A receptor is expressed in many inflammatory cells such as macrophages and T cells and has anti-inflammatory and antioxidant effects. Therefore, the GABA-A receptor may become a potential therapeutic target for abdominal aortic aneurysms. The purpose of this study was to investigate the effect of regulating the activity of the GABA-A receptor on the formation of experimental abdominal aortic aneurysm in rats. In this study, the abdominal aortic aneurysm model of rats was established by aorta intracavitary perfusion of elastase combined with aorta extracavitary infiltration of calcium chloride. GABA-A receptor agonist (topiramate) and antagonist (bicuculline) were used to treating the abdominal aortic aneurysm model rats, which were divided into sham operation group, model group, topiramate group, and bicuculline group(n = 10). Histopathology, immunohistochemistry, fluorescence quantitative PCR, Western blotting, ELISA and Gelatine zymogram were used to study. Regulation of GABA-A receptor activity can interfere with the development and severity of abdominal aortic aneurysms in rats. The GABA-A receptor agonist topiramate reduces the infiltration of inflammatory cells, particularly T cells, into the abdominal aortic wall, while also modulating the balance of Th1/Th2 cytokines in peripheral blood, leading to a significant reduction in inflammatory responses. Additionally, topiramate decreases the secretion of matrix metalloproteinases MMP2 and MMP9, thereby inhibiting extracellular matrix degradation and slowing the progression of aneurysms. In contrast, the GABA-A receptor antagonist bicuculline exacerbates inflammation and promotes aneurysm development. At the molecular level, the mechanisms of action of the GABA-A receptor agonist topiramate and the antagonist bicuculline may involve inhibition or activation of the p38 MAPK signaling pathway. Regulation of GABA-A receptor activity can effectively intervene in the occurrence and development of abdominal aortic aneurysms in rats.

Differential Expression Analyses on Human Aortic Tissue Reveal Novel Genes and Pathways Associated With Abdominal Aortic Aneurysm Onset and Progression

BACKGROUND

Abdominal aortic aneurysms (AAAs) are focal dilatations of the abdominal aorta that expand progressively, increasing their risk of rupture. Rupture of an AAA is associated with high mortality rates, but the mechanisms underlying the initiation, expansion, and rupture of AAAs are not yet fully understood. We aimed to characterize the pathophysiology of AAAs and identify new genes associated with AAA initiation and progression.

METHODS AND RESULTS

This study used RNA sequencing data on 140 samples, becoming the largest RNA sequencing data set for differential expression studies of AAAs. We performed differential expression analyses and analyses of differential splicing between dilated and nondilated aortic tissue samples, and between AAAs of different diameters. We identified 3002 differentially expressed genes between AAAs and controls that were independent of ischemic time, 1425 of which were new. Additionally, 8 genes (EXTL3, ZFR, DUSP8, DISP1, USP33, VPS37C, ZNF784, RFX1) were differentially expressed between AAAs of varying diameters and between AAAs and control samples. Finally, 7 genes (SPP1, FHL1, GNAS, MORF4L2, HMGN1, ARL1, RNASE4) with differential splicing patterns were also differentially expressed genes between AAAs and controls, suggesting that splicing differences in these genes may contribute to the observed expression changes and disease development.

CONCLUSIONS

This study identifies new genes and splicing patterns associated with AAAs and validates previous relevant pathways on AAAs. These findings contribute to the understanding of the complex mechanisms underlying AAAs and may provide potential targets to limit AAA progression and mortality risk.

CRP deposition in human abdominal aortic aneurysm is associated with transcriptome alterations toward aneurysmal pathogenesis: insights from in situ spatial whole transcriptomic analysis

Background

We investigated the effects of C-reactive protein (CRP) deposition on the vessel walls in abdominal aortic aneurysm (AAA) by analyzing spatially resolved changes in gene expression. Our aim was to elucidate the pathways that contribute to disease progression.

Methods

AAA specimens from surgically resected formalin-fixed paraffin-embedded tissues were categorized into the AAA-high CRP [serum CRP ≥ 0.1 mg/dL, diffuse and strong immunohistochemistry (IHC); n = 7 (12 cores)] and AAA-low-CRP [serum CRP < 0.1 mg/dL, weak IHC; n = 3 (5 cores)] groups. Normal aorta specimens obtained during heart transplantation were used as the control group [n = 3 (6 cores)]. Spatially resolved whole transcriptomic analysis was performed, focusing on CD68-positive macrophages, CD45-positive lymphocytes, and αSMA-positive vascular smooth muscle cells.

Results

Spatial whole transcriptomic analysis revealed significant differential expression of 1,086, 1,629, and 1,281 genes between high-CRP and low-CRP groups within CD68-, CD45-, and αSMA-positive cells, respectively. Gene ontology (GO) analysis of CD68-positive macrophages identified clusters related to inflammation, apoptosis, and immune response, with signal transducer and activator of transcription 3 implicated across three processes. Notably, genes involved in blood vessel diameter maintenance were significantly downregulated in the high-CRP group. GO analysis of lymphocytes showed upregulation of leukocyte rolling and the apoptosis pathway, whereas, in smooth muscle cells, genes associated with Nuclear factor kappa B (NF-κB) signaling and c-Jun N-terminal Kinase (JNK) pathway were upregulated, and those related to blood pressure regulation were downregulated in the high-CRP group.

Discussion

CRP deposition was associated with significant transcriptomic changes in macrophages, lymphocytes, and vascular smooth muscle cells in AAA, suggesting its potential role in promoting pro-inflammatory and apoptotic processes, as well as contributing to the degradation of vascular structure and elasticity.

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.

Mechanism and clinical implication of gut dysbiosis in degenerative abdominal aortic aneurysm: A systematic review

The gut microbiome is the entirety of microorganisms and their genomes residing in the gut, characterised by diversity, stability, and resilience. Disrupted gut microbiome has been implicated in multiple disease entities. The aim of this paper is to summarise the rapidly evolving contemporary evidence of gut dysbiosis on the development and progression of abdominal aortic aneurysm (AAA), discuss possible mechanisms, and explore potential microbiota-targeted interventions and prognostic markers for AAA. A systematic literature search was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, using PubMed, ScienceDirect, Web of Science, Ovid, Embase. Search terms of "microbiome" OR "dysbiosis" OR "microorganism"; AND "aneurysm" OR "dilatation" OR "aorta" were used. Study endpoints included effects of microbiota on AAA formation, effects of specific type of bacteria and its metabolite on AAA formation, and pre- or post-treatment by novel small-molecules/inhibitors. From May to August 2023, a total of twelve animal studies and eight human studies were included. Akkermansia muciniphila, Lactobacillus acidophilus and species from the Bacteroidetes phylum were associated with lower AAA incidence in both animal and human studies, while Proteobacteria phylum, Campylobacter, Fusobacterium and Faecalibacterium prausnitzii were found to be in abundance in the AAA group and were associated with larger aneurysms. The diversity of gut microbiota was inversely correlated with AAA diameter. Three important mechanisms were identified: including trimethylamine N-oxide pathway, butyric acid pathway, and aberrant tryptophan metabolism. With our expanding knowledge of the downstream pathogenic mechanisms of gut dysbiosis, novel therapeutics such as short-chain fatty acids and spermidine, as well as prognostic biomarkers such as TMAO have yielded promising preclinical results. In conclusion, there is strong evidence corroborating the role of gut dysbiosis in the pathogenesis of AAA, wherein its therapeutic and prognostic potential deserves further exploration.

Cysteine Leukotriene Receptor Antagonist-Montelukast-Treatment Improves Experimental Abdominal Aortic Aneurysms in Mice

Background: Cysteinyl leukotrienes (LTs) and their receptors are involved in the pathogenesis of abdominal aortic aneurysms (AAAs). However, whether CysLT1 receptor antagonists such as montelukast can influence experimental nondissecting AAA remains unclear. Methods: Nondissecting AAAs were induced in C57BL/6J mice by transient aortic luminal infusion of porcine pancreatic elastase (PPE). All animals were administrated montelukast (1 or 10 mg/kg, daily) or vehicle by gavage beginning 1 day before PPE infusion for 14 days. On day 0 (baseline) and day 14 after PPE infusion, abdominal aortic diameters were directly measured. Aortic aneurysmal segment samples were collected, and histopathological analysis was performed. Results: Compared to vehicle treatment, montelukast significantly decreased PPE infusion-induced aortic expansion in a dose-dependent manner (0.09-mm reduction at a low dose and 0.19-mm reduction at a high dose). Histopathological analysis also revealed that compared with vehicle treatment, montelukast treatment, especially in the high-dose group, significantly improved PPE-induced aortic elastin degradation and medial smooth muscle cell depletion. Both doses of montelukast also markedly decreased the number of local leucocytes, including macrophages, CD4+ T cells, CD8+ T cells, and B cells, infiltration and accumulation in aortic aneurysmal lesions. Montelukast treatment also downregulated matrix metalloproteinase 2 (MMP2) and MMP9 expression and inhibited mural angiogenesis in aneurysmal aortas. Conclusion: Montelukast treatment improves experimental nondissected AAAs in mice partly by improving aortic inflammation.

Vascular Mesenchymal Stromal Cells and Cellular Senescence: A Two-Case Study Investigating the Correlation Between an Inflammatory Microenvironment and Abdominal Aortic Aneurysm Development

An abdominal aortic aneurysm (AAA) is described as a gradual and localized permanent expansion of the aorta resulting from the weakening of the vascular wall. The key aspects of AAA's progression are high proteolysis of the structural elements of the vascular wall, the depletion of vascular smooth muscle cells (VSMCs), and a chronic immunoinflammatory response. The pathological mechanisms underpinning the development of an AAA are complex and still unknown. At present, there are no successful drug treatments available that can slow the progression of an AAA or prevent the rupture of the aneurysmal vascular wall. Recently, it has been suggested that endothelial cellular senescence may be involved in vascular aging and vascular aging diseases, but there is no clear correlation between cellular senescence and AAAs. Therefore, the aim of this study was to identify the presence of senescent cells on the vascular wall of aneurysmatic abdominal aortas and to correlate their distribution with the morphological markers of AAAs. Pathological and healthy segments of abdominal aortas were collected during repair surgery and immediately processed for histological and immunohistochemical analyses. Hematoxylin/eosin, Verhoeff-van Gieson, and Goldner's Masson trichrome staining procedures were carried out to investigate the morphological features related to the pathology. Immunohistochemical investigations for the p21cip1/waf1, p53, and NFkB markers were carried out to selectively identify positive cells in the vascular wall of the AAA samples related to cellular senescence and an inflammatory microenvironment. The results revealed the presence of a few senescent vascular cells on the aneurysmatic wall of the abdominal aortas, surrounded by a highly inflamed microenvironment that was highly expressed in the tunica media and adventitia of both pathological and healthy segments. Our data demonstrate the presence of senescent vascular cells in AAA samples, which could enhance the promotion of a high inflammatory vascular microenvironment, supporting the evolution of the pathology. Although this study was based on only two cases, the results highlight the importance of targeting cellular senescence to reduce an inflammatory microenvironment, which can support the progression of age-related diseases.

Feature genes identification and immune infiltration assessment in abdominal aortic aneurysm using WGCNA and machine learning algorithms

Objective

Abdominal aortic aneurysm (AAA) is a life-threatening vascular condition. This study aimed to discover new indicators for the early detection of AAA and explore the possible involvement of immune cell activity in its development.

Methods

Sourced from the Gene Expression Omnibus, the AAA microarray datasets GSE47472 and GSE57691 were combined to generate the training set. Additionally, a separate dataset (GSE7084) was designated as the validation set. Enrichment analyses were carried out to explore the underlying biological mechanisms using Disease Ontology, Kyoto Encyclopedia of Genes and Genomes, and Gene Ontology. We then utilized weighted gene co-expression network analysis (WGCNA) along with 3 machine learning techniques: least absolute shrinkage and selection operator, support vector machine-recursive feature elimination, and random forest, to identify feature genes for AAA. Moreover, data were validated using the receiver operating characteristic (ROC) curve, with feature genes defined as those having an area under the curve above 85% and a p-value below 0.05. Finally, the single sample gene set enrichment analysis algorithm was applied to probe the immune landscape in AAA and its connection to the selected feature genes.

Results

We discovered 72 differentially expressed genes (DEGs) when comparing healthy and AAA samples, including 36 upregulated and 36 downregulated genes. Functional enrichment analysis revealed that the DEGs associated with AAA are primarily involved in inflammatory regulation and immune response. By intersecting the result of 3 machine learning algorithms and WGCNA, 3 feature genes were identified, including MRAP2, PPP1R14A, and PLN genes. The diagnostic performance of all these genes was strong, as revealed by the ROC analysis. A significant increase in 15 immune cell types in AAA samples was observed, based on the analysis of immune cell infiltration. In addition, the 3 feature genes show a strong linkage with different types of immune cells.

Conclusion

Three feature genes (MRAP2, PPP1R14A, and PLN) related to the development of AAA were identified. These genes are linked to immune cell activity and the inflammatory microenvironment, providing potential biomarkers for early detection and a basis for further research into AAA progression.

A bibliometric and visualization analysis of global trends and frontiers on macrophages in abdominal aortic aneurysms research

BACKGROUND

Macrophages are key regulators of the inflammatory and innate immune responses. Researchers have shown that aberrant expression of macrophages contributes to the development of abdominal aortic aneurysms (AAA). However, a comprehensive bibliometric analysis exploring the research status and knowledge mapping of this area is lacking. This study aimed to explore the research status, knowledge mapping and hotspots of macrophages in AAA research from a bibliometric perspective.

METHODS

In this study, we retrieved articles published between 2000 and 2022 on macrophages associated with AAA research from the Web of Science Core Collection (WoSCC) database. The retrieved literature data were further analyzed using Citespace and VOSviewer software.

RESULTS

A total of 918 qualified publications related to AAA-associated macrophages were retrieved. The number of publications in this field has been increasing annually. China and the United States were the 2 main drivers in this field, contributing to more than 64% of the publications. In addition, the US had the most publications, top institutions, and expert researchers, dominating in research on macrophages in AAA. The Harvard University was the most productive institution, with 60 publications. The journal with the most publications was Arteriosclerosis, Thrombosis, and Vascular Biology (86). Daugherty Alan was the most prolific author (28 publications) and he was also the most cited co- author. Furthermore, the exploration of established animal models, macrophage-related inflammatory-microenvironment, macrophage-related immune mechanism, clinical translation and molecular imaging research remained future research directions in this field.

CONCLUSIONS

Our findings offered new insights for scholars in this field. They will help researchers explore new directions for their work.

Targeting the smooth muscle cell Keap1-Nrf2-GSDMD-pyroptosis axis by cryptotanshinone prevents abdominal aortic aneurysm formation

Rationale: Abdominal aortic aneurysm (AAA) is an inflammatory, fatal aortic disease that currently lacks any effective drugs. Cryptotanshinone (CTS) is a prominent and inexpensive bioactive substance derived from Salvia miltiorrhiza Bunge, a well-known medicinal herb for treating cardiovascular diseases through its potent anti-inflammatory properties. Nevertheless, the therapeutic effect of CTS on AAA formation remains unknown. Methods: To investigate the therapeutic effect of CTS in AAA, variety of experimental approaches were employed, majorly including AAA mouse model establishment, real-time polymerase chain reaction (PCR), RNA sequencing, western blot, co-immunoprecipitation, scanning/transmission electron microscopy (SEM/TEM), enzyme-linked immunosorbent assay (ELISA), seahorse analysis, immunohistochemistry, and confocal imaging. Results: In this study, we demonstrated that CTS suppressed the formation of AAA in apolipoprotein E knock-out (ApoE-/-) mice infused with Ang II. A combination of network pharmacology and whole transcriptome sequencing analysis indicated that activation of the Keap1-Nrf2 pathway and regulation of programmed cell death in vascular smooth muscle cells (VSMCs) are closely linked to the anti-AAA effect of CTS. Mechanistically, CTS promoted the transcription of Nrf2 target genes, particularly Hmox-1, which prevented the activation of NLRP3 and GSDMD-initiated pyroptosis in VSMCs, thereby mitigating VSMC inflammation and maintaining the VSMC contractile phenotype. Subsequently, by utilizing molecular docking, together with the cellular thermal shift assay (CETSA) and isothermal titration calorimetry (ITC), a particular binding site was established between CTS and Keap1 at Arg415. To confirm the binding site, site-directed mutagenesis was performed, which intriguingly showed that the Arg415 mutation eliminated the binding between CTS and the Keap1-Nrf2 protein and abrogated the antioxidant and anti-pyroptosis effects of CTS. Furthermore, VSMC-specific Nrf2 knockdown in mice dramatically reversed the protective action of CTS in AAA and the inhibitory effect of CTS on VSMC pyroptosis. Conclusion: Naturally derived CTS exhibits promising efficacy as a treatment drug for AAA through its targeting of the Keap1-Nrf2-GSDMD-pyroptosis axis in VSMCs.

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.

The potential of a nomogram risk assessment model for the diagnosis of abdominal aortic aneurysm: a multicenter retrospective study

The incidence of abdominal aortic aneurysm (AAA) is very high, but there is no risk assessment model for early identification of AAA in clinic. The aim of this study was to develop a nomogram risk assessment model for predicting AAA. The data of 280 patients diagnosed as AAA and 385 controls in The Affiliated Suzhou Hospital of Nanjing Medical University were retrospectively reviewed. The LASSO regression method was applied to filter variables, and multivariate logistic regression was used to construct a nomogram. The discriminatory ability of the model was determined by calculating the area under the curve (AUC). The calibration capability of the model is evaluated by using bootstrap (resampling = 1000) internal validation and Hosmer-Lemeshow test. The clinical utility and clinical application value were evaluated by decision curve analysis (DCA) and clinical impact curve (CIC). In addition, a retrospective review of 133 AAA patients and 262 controls from The First Affiliated Hospital of Soochow University was performed as an external validation cohort. Eight variables are selected to construct the nomogram of AAA risk assessment model. The nomogram predicted AAA with AUC values of 0.928 (95%CI, 0.907-0.950) in the training cohort, and 0.902 (95%CI, 0.865-0.940) in the external validation cohort, the risk prediction model has excellent discriminative ability. The calibration curve and Hosmer-Lemeshow test proved that the nomogram predicted outcomes were close to the ideal curve, the predicted outcomes were consistent with the real outcomes, the DCA curve and CIC curve showed that patients could benefit. This finding was also confirmed in the external validation cohort. In this study, a nomogram was constructed that incorporated eight demographic and clinical characteristics of AAA patients, which can be used as a practical approach for the personalized early screening and auxiliary diagnosis of the potential risk factors.

GSDMB involvement in the pathogenesis of abdominal aortic aneurysm through regulation of macrophage non-canonical pyroptosis

Abdominal aortic aneurysm (AAA) is a dangerous condition affecting the aorta. Macrophage pyroptosis, phenotypic transformation, and apoptosis of aortic smooth muscle cells (ASMCs) are pivotal mechanisms in AAA pathogenesis. This study explores how Gasdermin B (GSDMB) regulates macrophage non-canonical pyroptosis and its impact on the phenotypic transformation and apoptosis of ASMCs, thereby unveiling the role of GSDMB in AAA pathogenesis. Immunofluorescence analysis was used to assess the expression levels and localization of GSDMB, cysteinyl aspartate-specific protease-4 (Caspase-4), and N-terminal of cleaved GSDMD (N-GSDMD) in AAA tissues. A cell model that mimics macrophage non-canonical pyroptosis was established by treating THP-1 cells with lipopolysaccharide (LPS). THP-1 cells with reduced or increased GSDMB were generated using small interfering RNA (siRNA) or plasmids. Co-culture experiments involving THP-1 cells and HASMCs were conducted to explore the impact of GSDMB on HASMCs. The mitochondrial reactive oxygen species (mtROS) scavenger Mito-TEMPO lowered mtROS levels in THP-1 cells. Our findings revealed that GSDMB was significantly upregulated in AAA macrophages, which was accompanied by robust non-canonical pyroptosis. THP-1 cells showed non-canonical pyroptosis in response to LPS, which was accompanied by an increase in GSDMB. Further research demonstrated that altering GSDMB, either by knockdown or overexpression, can affect macrophage non-canonical pyroptosis as well as the phenotypic transformation and apoptosis of HASMCs. LPS-induced non-canonical pyroptosis in THP-1 cells was associated with an increase in mtROS, whereas Mito-TEMPO effectively decreased non-canonical pyroptosis and the expression of GSDMB. These findings suggest that GSDMB plays a role in AAA macrophage non-canonical pyroptosis, which influences the phenotypic transformation and apoptosis of HASMCs. The mtROS-Dynamin-Related Protein 1 (Drp1) axis is likely to regulate the GSDMB-mediated non-canonical pyroptosis.

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.

Relationship between Gut, Blood, Aneurysm Wall and Thrombus Microbiome in Abdominal Aortic Aneurysm Patients

Previous research confirmed gut dysbiosis and translocation of selected intestinal bacteria into the vessel wall in abdominal aortic aneurysm patients. We studied the stool, blood, thrombus and aneurysm microbiomes of 21 abdominal aortic aneurysm patients using 16S rRNA sequencing. Our goals were to determine: 1. whether the microbiome characteristic of an aneurysm differs from that of a healthy vessel, 2. whether bacteria detectable in the aneurysm are translocated from the gut through the bloodstream, 3. whether the enzymatic activity of the aneurysm microbiome can contribute to the destruction of the vessel wall. The abundance of Acinetobacter, Burkholderia, Escherichia, and Sphingobium in the aneurysm samples was significantly higher than that in the microbiome of healthy vessels, but only a part of these bacteria can come from the intestine via the blood. Environmental bacteria due to the oral cavity or skin penetration route, such as Acinetobacter, Sphingobium, Enhydrobacter, and Aquabacterium, were present in the thrombus and aneurysm with a significantly higher abundance compared to the blood. Among the enzymes of the microbiome associated with the healthy vessel wall, Iron-chelate-transporting ATPase and Polar-amino-acid-transporting ATPase have protective effects. In addition, bacterial Peptidylprolyl isomerase activity found in the aneurysm has an aggravating effect on the formation of aneurysm.

PI3Kγ promotes neutrophil extracellular trap formation by noncanonical pyroptosis in abdominal aortic aneurysm

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

A porcine model of thoracic aortic aneurysms created with a retrievable drug infusion stent graft mirrors human aneurysm pathophysiology

Objective

Aneurysm pathophysiology remains poorly understood, in part from the disparity of murine models with human physiology and the requirement for invasive aortic exposure to apply agents used to create aneurysm models. A retrievable drug infusion stent graft (RDIS) was developed to isolate the aortic wall intraluminally for drug exposure. We hypothesized that an RDIS could deliver aneurysm-promoting enzymes to create a porcine model of thoracic aneurysms without major surgical exposure.

Methods

Retrievable nitinol stent graft frames were designed with an isolated drug delivery chamber, covered with polytetrafluoroethylene, and connected to a delivery wire with a drug infusion catheter installed to the outer chamber. Institutional Animal Care and Use Committee-approved Yorkshire pigs (n = 5) underwent percutaneous access of the femoral artery, baseline aortogram and stent placement in the thoracic aorta followed by 30-minute exposure to a cocktail of elastase, collagenase, and trypsin. After aspiration of excess drug, stent retrieval, and femoral artery repair, animals were recovered, with angiograms at 1 and 4 weeks followed by explant. Histological analysis, in situ zymography, and multiplex cytokine assays were performed.

Results

The RDIS isolated a segment of anterior aorta angiographically, while the center lumen preserved distal perfusion during drug treatment (baseline femoral mean arterial pressure, 70 ± 14 mm Hg; after RDIS, 75 ± 12; P = .55). Endovascular induction of thoracic aneurysms did not require prior mechanical injury and animals revealed no evidence of toxicity. Within 1 week, significant aneurysmal growth was observed in all five animals (1.4 ± 0.1 cm baseline to 2.9 ± 0.7 cm; P = .002) and only within the treated region of the aorta. Aneurysms persisted out to 4 weeks. Aneurysm histology demonstrated loss of elastin and collagen that was otherwise preserved in untreated aorta. Proinflammatory cytokines and increased matrix metalloproteinase activity were increased significantly within the aneurysm.

Conclusions

An RDIS achieves isolated drug delivery while preserving distal perfusion to achieve an endovascular porcine model of thoracic aneurysms without major surgery. This model may have value for surgical training, device testing, and to better understand aneurysm pathogenesis. Most important, although the RDIS was used to simulate aortic pathology, this tool offers intriguing horizons for focused therapeutic drug delivery directly to aneurysms and, more broadly, focused locoregional drug delivery to vessels and vascular beds.

MEK inhibitors: a promising targeted therapy for cardiovascular disease

Cardiovascular disease (CVD) represents the leading cause of mortality and disability all over the world. Identifying new targeted therapeutic approaches has become a priority of biomedical research to improve patient outcomes and quality of life. The RAS-RAF-MEK (mitogen-activated protein kinase kinase)-ERK (extracellular signal-regulated kinase) pathway is gaining growing interest as a potential signaling cascade implicated in the pathogenesis of CVD. This pathway is pivotal in regulating cellular processes like proliferation, growth, migration, differentiation, and survival, which are vital in maintaining cardiovascular homeostasis. In addition, ERK signaling is involved in controlling angiogenesis, vascular tone, myocardial contractility, and oxidative stress. Dysregulation of this signaling cascade has been linked to cell dysfunction and vascular and cardiac pathological remodeling, which contribute to the onset and progression of CVD. Recent and ongoing research has provided insights into potential therapeutic interventions targeting the RAS-RAF-MEK-ERK pathway to improve cardiovascular pathologies. Preclinical studies have demonstrated the efficacy of targeted therapy with MEK inhibitors (MEKI) in attenuating ERK activation and mitigating CVD progression in animal models. In this article, we first describe how ERK signaling contributes to preserving cardiovascular health. We then summarize current knowledge of the roles played by ERK in the development and progression of cardiac and vascular disorders, including atherosclerosis, myocardial infarction, cardiac hypertrophy, heart failure, and aortic aneurysm. We finally report novel therapeutic strategies for these CVDs encompassing MEKI and discuss advantages, challenges, and future developments for MEKI therapeutics.

Gasdermin D Inhibitor Necrosulfonamide Alleviates Angiotensin II-Induced Abdominal Aortic Aneurysms in Apolipoprotein E-Deficient Mice

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

Assessing the causal relationship between circulating immune cells and abdominal aortic aneurysm by bi-directional Mendelian randomization analysis

Although there is an association between abdominal aortic aneurysm (AAA) and circulating immune cell phenotypes, the exact causal relationship remains unclear. This study aimed to explore the causal relationships between immune cell phenotypes and AAA risk using a bidirectional two-sample Mendelian randomization approach. Data from genome-wide association studies pertaining to 731 immune cell traits and AAA were systematically analyzed. Using strict selection criteria, we identified 339 immune traits that are associated with at least 3 single nucleotide polymorphisms. A comprehensive MR analysis was conducted using several methods including Inverse Variance Weighted, Weighted Median Estimator, MR-Egger regression, Weighted Mode, and Simple Median methods. CD24 on switched memory cells (OR = 0.922, 95% CI 0.914-0.929, P = 2.62e-79) at the median fluorescence intensities level, and SSC-A on HLA-DR + natural killer cells (OR = 0.873, 95% CI 0.861-0.885, P = 8.96e-81) at the morphological parameter level, exhibited the strongest causal associations with AAA. In the reverse analysis, no significant causal effects of AAA on immune traits were found. The study elucidates the causal involvement of multiple circulating immune cell phenotypes in AAA development, signifying their potential as diagnostic markers or therapeutic targets. These identified immune traits may be crucial in modulating AAA-related inflammatory pathways.

Causal relationship between immune cells and aortic aneurysms: a Mendelian randomization study

OBJECTIVES

The causal association between immune cell traits and aortic aneurysm remains unknown.

METHODS

We performed a bidirectional two-sample Mendelian randomization analysis to explore the causality between 731 immune cell characteristics and the risk of abdominal aortic aneurysm and thoracic aortic aneurysms through publicly available genetic data, respectively. To examine heterogeneity and horizontal pleiotropy, Cochran's Q test and MR-Egger intercept were utilized. Additionally, multivariable Mendelian randomization analysis and meta-analysis were performed in further analysis.

RESULTS

We found that 20 immune phenotypes had a suggestive causality on abdominal aortic aneurysm, and 15 immune phenotypes had a suggestive causal effect on thoracic aortic aneurysm. After further false discovery rate adjustment (q value <0.1), CD20 on IgD+ CD38- B cell (q = 0.053) and CD127 on CD28+ CD4+ T cell (q = 0.096) were associated with an increased risk of abdominal aortic aneurysm, respectively, indicating a significant causality between them. After adjusting for smoking, there is still statistical significance between CD127 on CD28+ CD4+ T cell and abdominal aortic aneurysm. However, after adjusting for lipids, no statistical significance can be observed between CD127 on CD28+ CD4+ T cells and abdominal aortic aneurysm. Furthermore, there is still statistical significance between CD20 on IgD+ CD38- B cells and abdominal aortic aneurysm after adjusting for lipids and smoking, which was further identified by meta-analysis.

CONCLUSIONS

We found a causal association between immune cell traits and aortic aneurysm by genetic methods, thus providing new avenues for future mechanism studies.

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.

Identification of biomarkers for abdominal aortic aneurysm in Behçet's disease via mendelian randomization and integrated bioinformatics analyses

Behçet's disease (BD) is a complex autoimmune disorder impacting several organ systems. Although the involvement of abdominal aortic aneurysm (AAA) in BD is rare, it can be associated with severe consequences. In the present study, we identified diagnostic biomarkers in patients with BD having AAA. Mendelian randomization (MR) analysis was initially used to explore the potential causal association between BD and AAA. The Limma package, WGCNA, PPI and machine learning algorithms were employed to identify potential diagnostic genes. A receiver operating characteristic curve (ROC) for the nomogram was constructed to ascertain the diagnostic value of AAA in patients with BD. Finally, immune cell infiltration analyses and single-sample gene set enrichment analysis (ssGSEA) were conducted. The MR analysis indicated a suggestive association between BD and the risk of AAA (odds ratio [OR]: 1.0384, 95% confidence interval [CI]: 1.0081-1.0696, p = 0.0126). Three hub genes (CD247, CD2 and CCR7) were identified using the integrated bioinformatics analyses, which were subsequently utilised to construct a nomogram (area under the curve [AUC]: 0.982, 95% CI: 0.944-1.000). Finally, the immune cell infiltration assay revealed that dysregulation immune cells were positively correlated with the three hub genes. Our MR analyses revealed a higher susceptibility of patients with BD to AAA. We used a systematic approach to identify three potential hub genes (CD247, CD2 and CCR7) and developed a nomogram to assist in the diagnosis of AAA among patients with BD. In addition, immune cell infiltration analysis indicated the dysregulation in immune cell proportions.

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.

Dysfunctional regulatory T cell: May be an obstacle to immunotherapy in cardiovascular diseases

Inflammatory responses are linked to cardiovascular diseases (CVDs) in various forms. Tregs, members of CD4+ T cells, play important roles in regulating immune system and suppressing inflammatory response, thus contributing to maintaining immune homeostasis. However, Tregs exert their powerful suppressive function relying on the stable phenotype and function. The stability of Tregs primarily depends on the FOXP3 (Forkhead box P3) expression and epigenetic regulation. Although Tregs are quite stable under physiological conditions, prolonged exposure to inflammatory cues, Tregs may lose suppressive function and require proinflammatory phenotype, namely plastic Tregs or ex-Tregs. There are extensive researches have established the beneficial role of Tregs in CVDs. Nevertheless, the potential risks of dysfunctional Tregs lack deep research. Anti-inflammatory and immunological modulation have been hotspots in the treatment of CVDs. Tregs are appealing because of their crucial role in resolving inflammation and promoting tissue repair. If alleviating inflammatory response through modulating Tregs could be a new therapeutic strategy for CVDs, the next step to consider is how to prevent the formation of dysfunctional Tregs or reverse detrimental Tregs to normal phenotype.

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.

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.

Trimethylamine N-oxide promotes abdominal aortic aneurysm by inducing vascular inflammation and vascular smooth muscle cell phenotypic switching

OBJECTIVE

Inflammation and vascular smooth muscle cell (VSMC) phenotypic switching are implicated in the pathogenesis of abdominal aortic aneurysm (AAA). Trimethylamine N-oxide (TMAO) has emerged as a crucial risk factor in cardiovascular diseases, inducing vascular inflammation and calcification. We aimed to evaluate the effect of TMAO on the formation of AAA.

APPROACH AND RESULTS

Here, we showed that TMAO was elevated in plasma from AAA patients compared with nonaneurysmal subjects by liquid chromatography‒mass spectrometry (LC‒MS) detection. Functional studies revealed that increased TMAO induced by feeding a choline-supplemented diet promoted Ang II-induced AAA formation. Immunohistochemistry, enzyme-linked immunosorbent assay (ELISA), and Western blot analyses revealed that TMAO induced macrophage infiltration and inflammatory factor release. Conversely, inhibition of TMAO by supplementation with DMB suppressed AAA formation and the inflammatory response. Molecular studies revealed that TMAO regulated VSMC phenotypic switching. Flow cytometry analyses showed that TMAO induces macrophage M1-type polarization. Furthermore, pharmacological intervention experiments suggested that the nuclear factor-κB (NF-κB) signaling pathway was critical for TMAO to trigger AAA formation.

CONCLUSIONS

TMAO promotes AAA formation by inducing vascular inflammation and VSMC phenotypic switching through activation of the NF-κB signaling pathway. Thus, TMAO is a prospective therapeutic AAA target.