Endothelial Dysfunction in the Pathogenesis of Abdominal Aortic Aneurysm

Endothelial miR-34a deletion guards against aneurysm development despite endothelial dysfunction

We previously reported a link between NRF2, a cytoprotective transcription factor, and the ageing of endothelial cells (ECs) and aorta. We also found that NRF2 KO mice are more susceptible to the development of abdominal aortic aneurysm (AAA), which is an age-associated condition. Since miR-34a is a marker of ageing, we explored its relationship with NRF2 and its role in vascular function and AAA formation. Here, we demonstrate that premature NRF2-dependent ageing of ECs is mediated by miR-34a. Infusion of hypertensive angiotensin II (Ang II) in mice increases miR-34a in the aortic endothelial layer and serum, particularly in mice developing AAA. Mice lacking endothelial miR-34a exhibit severe EC dysfunction. Despite that, they are protected from AAA, also on the NRF2 KO background. This protective effect is reversed by rapamycin, which suppresses Ang II-induced EC proliferation. We identified MTA2, but not SIRT1, as a target of miR-34a that inhibits EC proliferation stimulated by Ang II. These findings suggest that fine-tuning of EC proliferation could have potential therapeutic implications for the treatment of aneurysms.

Endothelial Cell Senescence in Marfan Syndrome: Pathogenesis and Therapeutic Potential of TGF-β Pathway Inhibition

BACKGROUND

Marfan syndrome (MFS) is a heritable connective tissue disorder caused by mutations in the Fibrillin-1 gene, which encodes the extracellular matrix protein fibrillin-1. Patients with MFS are predisposed to aortic aneurysms and dissections, significantly contributing to mortality. Emerging evidence suggests that endothelial cell (EC) senescence plays a critical role in the pathogenesis of aortic aneurysms in MFS. This study aims to elucidate the role of EC senescence in the development of aortic aneurysms in MFS using a vascular model derived from human induced pluripotent stem cells.

METHODS AND RESULTS

We generated human induced pluripotent stem cells lines from 2 patients with MFS carrying specific Fibrillin-1 mutations and differentiated these into ECs. These MFS-hiPSC-derived ECs were characterized using immunofluorescence, reverse transcription-quantitative polymerase chain reaction, and Western blotting. Functional assays including cell proliferation, scratch wound, tube formation, NO content detection, and senescence-associated β-galactosidase staining were conducted. RNA sequencing was performed to elucidate underlying signaling pathways, and pharmacological inhibition of the transforming growth factor-beta pathway was assessed for its therapeutic potential. MFS-hiPSC-derived ECs recapitulated the pathological features observed in Marfan aortas, particularly pronounced cellular senescence, decreased cell proliferation, and abnormal transforming growth factor-beta and NF-κB signaling. These senescent ECs exhibited diminished proliferative and migratory capacities, reduced NO signaling, increased production of inflammatory cytokines, and attenuated responses to inflammatory stimuli. Importantly, senescence and dysfunction in MFS-hiPSCderived ECs were ameliorated by transforming growth factor-beta signaling pathway inhibitor, SB-431542, suggesting a potential therapeutic strategy.

CONCLUSIONS

This study highlights the pivotal role of endothelial cell senescence in the pathogenesis of aortic aneurysms in MFS. Our human induced pluripotent stem cells-based disease model provides new insights into the disease mechanisms and underscores the potential of targeting the transforming growth factor-beta pathway to mitigate endothelial dysfunction and senescence, offering a promising therapeutic avenue for MFS.

Inhibition of bone morphogenetic protein 4 alleviates angiotensin II-induced abdominal aortic aneurysm by reducing inflammation and endothelial-mesenchymal transition

BACKGROUND AND AIMS

Abdominal aortic aneurysm (AAA) is one of the most common fatal macrovascular diseases worldwide which pathogenesis is still not well clarified. In this study, we systematically investigated the alternations of endothelial cell (ECs) functions and phenotypes by single-cell RNA sequencing in angiotensin (Ang) II-induced AAA mice models.

METHOD AND RESULTS

According to 10 × single-cell sequencing analysis, we revealed that ECs inflammation and endothelial-mesenchymal transition (EndoMT) were involved in the progress of Ang II-induced AAA. Three types of ECs, including Mature ECs (uninjured ECs), EndoMT ECs and Injury & inflammation ECs successively emerged during the progression of AAA. By using pseudotime-trajectory analysis, we speculated bone morphogenetic protein 4 (BMP4) as a candidate gene, participating in Ang II-induced AAA by regulating EndoMT and vascular inflammation. We found that inhibition of BMP4 ameliorated EndoMT and vascular inflammation in Ang II-induced AAA in vivo. In addition, we found that exogenous BMP4 directly promoted the phenotypic transition, inflammation, cell migration and invasion of mouse aortic endothelial cells via PI3K/AKT/mTOR pathways in vitro. Finally, Protein-protein interaction (PPI) analysis and co-immunoprecipitation (Co-IP) revealed that biglycan (BGN) directly combined with BMP4 and promoted the conversion of EndoMT.

CONCLUSION

Our findings firstly revealed a critical role of BMP4 in AAA progression, which promoted disease progression by inducing EndoMT and reprogramming ECs from anti-inflammatory to proinflammatory phenotype.

Right-sided Aortic Torsion in Patients with Abdominal Aortic Aneurysms

OBJECTIVES

Altered flow dynamics within abdominal aortic aneurysms (AAA) may lead to changes in aneurysmal geometry, intraluminal thrombus (ILT) deposition, or aneurysmal progression. Aortic torsion is one geometric deviation that has been clinically observed but has not been formally evaluated in pre-operative AAAs. This pilot retrospective cohort study investigates the degree and directionality of aortic torsion in patients with and without AAAs.

METHODS

The inferior mesenteric artery (IMA-Angle) outlet angle was used to assess aortic torsion. Angles were measured with respect to the anterior-posterior axis in both aneurysmal (370) and non-aneurysmal (120) patients. Patient age, gender, maximum infrarenal aortic/AAA diameter (DMax), and presence/percentage of ILT were calculated.

RESULTS

370 AAA patients (Age: 74 [65:83], %Male: 88%, DMax: 50.1 mm [41.9 - 57.0 mm]) were retrospectively identified. ILT was present in 65% of cases and comprised 26.2% of the aneurysmal sac [18.6 - 36.7%]. Similarly, 120 patients without aneurysmal disease were identified (Age: 70 [63:81], %Male: 79%, DMax: 23.3 mm [21.5 - 25.6]). Median IMA-Angle [25th-75th%] in the aneurysmal cohort was 17.0° [8.6° - 25.3°] and closer to the AP axis compared to controls (38.5° [34.3° - 44.9°], p < 0.001). Presence, percentage, and classification of ILT (r = 0.01, p = 0.93) had negligible impact on IMA outlet angle.

CONCLUSION

This study highlights the right-sided IMA preference in AAA patients compared to non-aneurysmal controls. The pathophysiology underlying this rotation may be associated with a right-sided helical flow pattern in expanding aneurysmal sacs. This sets the foundation for future investigations.

Blood Eosinophil Count in Asthma Is Associated With Increased Abdominal Aortic Diameter and Increased Vascular Stiffness

Background

Asthma is associated with atherosclerosis and abdominal aortic aneurysm (AAA). However, the underlying pathomechanisms remain elusive. Blood eosinophil count (BEC) is implicated in both eosinophilic asthma and arterial wall inflammation.

Objective

To explore the possible association of BEC in asthma and abdominal aortic artery changes.

Methods

112 outpatients were prospectively enrolled in this exploratory study. Abdominal aortic diameter was measured using ultrasonography imaging, while vascular speckle tracking was utilized to evaluate vascular strains. Patients were stratified into two groups, with n=66 patients with a BEC of ≥300 n/µL and n=46 patients with <300 n/µL. Both groups exhibited no significant disparities in cardiovascular risk factors; however, the high BEC group was more frequently male.

Results

The aortic diameter was wider in patients with a BEC ≥300 n/µL (1.46 ± 0.25 cm vs 1.67 ± 0.63 cm, p=0.018). Three patients were diagnosed with an AAA, all had a BEC ≥300 n/µL. Patients with a BEC ≥300 n/µL exhibited lower strain values, indicative of higher vascular stiffness, including radial strain (2.65 ± 1.38% vs 4.46 ± 2.59%; p<0.001). BEC exhibited a positive correlation with abdominal aortic diameter (R²=0.131, b=0.000, p<0.001), and a negative correlation with radial strain values (R²=0.131, b=-0.002, p=0.001) in sex-adjusted linear regression.

Conclusion

In patients with asthma, blood eosinophil count (BEC) is correlated with a wider aortic diameter and heightened vascular stiffness in the abdominal aorta. Hence, they may be at an elevated risk of developing an AAA.

Aneurysm Is Restricted by CD34+ Cell-Formed Fibrous Collars Through the PDGFRb-PI3K Axis

Aortic aneurysm is a life-threatening disease caused by progressive dilation of the aorta and weakened aortic walls. Its pathogenesis involves an imbalance between connective tissue repair and degradation. CD34+ cells comprise a heterogeneous population that exhibits stem cell and progenitor cell properties. However, the role of CD34+ cells in abdominal aortic aneurysm (AAA) remains unclear. In this study, downregulated CD34 expression is observed in aneurysmal aortas from both patients and mouse models compared to that in non-dilated aortas. Furthermore, by combining Cd34-CreERT2;Rosa26-tdTomato;(Apoe-/-) lineage tracing, bone marrow transplantation, and single-cell sequencing, it is found that during AAA development, non-bone marrow CD34+ cells are activated to transdifferentiate into Periostin+ myofibroblasts, thereby contributing to the formation of fibrotic collars. Dual recombinase-based lineage tracing confirms the presence and involvement of CD34+/Periostin+ myofibroblasts in fibrotic collar formation during AAA development. Functionally, selective depletion of systemic or non-bone marrow CD34+ cells, as well as CD34+/Periostin+ myofibroblasts, by diphtheria toxin significantly exacerbates AAA progression and increases disease mortality. Mechanistically, it is identified that the PDGF-PDGFRb-PI3K axis is indispensable for Periostin+ myofibroblast generation from non-bone marrow CD34+ cells in AAA, offering a new therapeutic target for patients with AAA at a high risk of rupture.

Inhibition of GPR4 Attenuates the Formation of Abdominal Aortic Aneurysm Through Inhibiting the SP-1/VEGF-A Signaling

Abdominal aortic aneurysm (AAA) is a severe cardiovascular disease (CVD) that is partly attributable to endothelial dysfunction, inflammatory response, and angiogenesis. G protein-coupled receptor 4 (GPR4), a proton-sensitive G protein-coupled receptor that is abundantly expressed in vascular endothelial cells, has been associated with numerous physiological functions. Nevertheless, its potential involvement in the development of AAA remains unexplored. In this study, we examined the impact of GPR4 deletion on the development of AAA in ApoE-deficient mice. The mice were categorized into four distinct groups: the ApoE-/- with saline group, the ApoE-/-GPR4-/- with saline group, the ApoE-/- with Ang II group, and the ApoE-/-GPR4-/- with Ang II group. AAA were induced in the ApoE-/- mice through the perfusion of angiotensin II (Ang II). Notably, GPR4 was substantially elevated in the AAA tissues from both human subjects and experimental mice. The deletion of GPR4 substantially decreased the formation of Ang II-induced AAA, damages to elastin, and the expression of aortic inflammatory cytokines interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α), as well as vascular endothelial growth factor A/vascular endothelial growth factor receptor 2 (VEGF-A/VEGF-R2), in ApoE-/- mice. Human aortic endothelial cells (HAECs) were transfected with lenti-viral GPR4 shRNA and subsequently stimulated with Ang II. Our findings indicate that the knockout of GPR4 attenuated Ang II-induced angiogenic tube formation in HAECs by decreasing the expression of VEGF-A and VEGF-R2. Furthermore, GPR4 knockout also hindered the activation of specificity protein-1 (SP-1) by reducing its expression and transcriptional activity. Notably, the overexpression of SP-1 reversed the inhibitory effects of GPR4 knockout on angiogenic tube formation and the expression of VEGF-A/VEGF-R2. This suggests that the protective effects of GPR4 knockout are achieved through the inhibition of SP-1. In summary, the absence of GPR4 impeded AAA formation, indicating that GPR4 could potentially serve as a therapeutic target for AAA.

Impact of Vein Wall Hyperelasticity and Blood Flow Turbulence on Hemodynamic Parameters in the Inferior Vena Cava with a Filter

Inferior vena cava (IVC) filters are vital in preventing pulmonary embolism (PE) by trapping large blood clots, especially in patients unsuitable for anticoagulation. In this study, the accuracy of two common simplifying assumptions in numerical studies of IVC filters-the rigid wall assumption and the laminar flow model-is examined, contrasting them with more realistic hyperelastic wall and turbulent flow models. Using fluid-structure interaction (FSI) and computational fluid dynamics (CFD) techniques, the investigation focuses on three hemodynamic parameters: time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and relative residence time (RRT). Simulations are conducted with varying sizes of clots captured in the filter. The findings show that, in regions of high wall shear stress, the rigid wall model predicted higher TAWSS values, suggesting an increased disease risk compared to the hyperelastic model. However, the laminar and turbulent flow models did not show significant differences in TAWSS predictions. Conversely, in areas of low wall shear stress, the rigid wall model indicated lower OSI and RRT, hinting at a reduced risk compared to the hyperelastic model, with this discrepancy being more evident with larger clots. While the predictions for OSI and TAWSS were closely aligned for both laminar and turbulent flows, divergences in RRT predictions became apparent, especially in scenarios with very large clots.

Olfactory Receptors and Aortic Aneurysm: Review of Disease Pathways

Aortic aneurysm, the pathological dilatation of the aorta at distinct locations, can be attributed to many different genetic and environmental factors. The resulting pathobiological disturbances generate a complex interplay of processes affecting cells and extracellular molecules of the tunica interna, media and externa. In short, aortic aneurysm can affect processes involving the extracellular matrix, lipid trafficking/atherosclerosis, vascular smooth muscle cells, inflammation, platelets and intraluminal thrombus formation, as well as various endothelial functions. Many of these processes are interconnected, potentiating one another. Newer discoveries, including the involvement of odorant olfactory receptors in these processes, have further shed light on disease initiation and pathology. Olfactory receptors are a varied group of G protein coupled-receptors responsible for the recognition of chemosensory information. Although they comprise many different subgroups, some of which are not well-characterized or identified in humans, odorant olfactory receptors, in particular, are most commonly associated with recognition of olfactory information. They can also be ectopically localized and thus carry out additional functions relevant to the tissue in which they are identified. It is thus the purpose of this narrative review to summarize and present pathobiological processes relevant to the initiation and propagation of aortic aneurysm, while also incorporating evidence associating these ectopically functioning odorant olfactory receptors with the overall pathology.

Role of inflammasomes in endothelial dysfunction

The vascular endothelium dynamically responds to environmental cues and plays a pivotal role in maintaining vascular homeostasis by regulating vasomotor tone, blood cell trafficking, permeability and immune responses. However, endothelial dysfunction results in various pathological conditions. Inflammasomes are large intracellular multimeric complexes activated by pathogens or cellular damage. Inflammasomes in vascular endothelial cells (ECs) initiate innate immune responses, which have emerged as significant mediators in endothelial dysfunction, contributing to the pathophysiology of an array of diseases. This review summarizes the mechanisms and ramifications of inflammasomes in ECs and related vascular diseases such as atherosclerosis, abdominal aortic aneurysm, stroke, and lung and kidney diseases. We also discuss potential drugs targeting EC inflammasomes and their applications in treating vascular diseases.

Spontaneous rupture of an ovarian artery aneurysm complicated by postpartum hypertensive disorders of pregnancy after caesarean section: a case report and literature review

BACKGROUND

The spontaneous rupture of an artery aneurysm during the perinatal period is considered a serious complication associated with the physiological alteration by pregnancy and delivery. The rupture of an ovarian artery aneurysm is rare and leads to rapid retroperitoneal hemorrhage. Here, we report one case complicated by postpartum hypertensive disorder of pregnancy associated with massive bleeding into retroperitoneal cavity by the spontaneous rupture of ovarian artery aneurysm after caesarean section, and reviewed previous literature.

CASE PRESENTATION

A 41-year-old Japanese woman was referred to our hospital four days after undergoing cesarean delivery because of hemorrhagic shock with abdominal and right flank pain. Contrast-enhanced computed tomography revealed a large retroperitoneal hematoma. Angiography showed a ruptured right ovarian artery aneurysm, anastomosing with a dilated uterine artery. She was successfully treated with transcatheter arterial embolization. She was diagnosed with postpartum hypertensive disorder of pregnancy 3 days after the embolization.

CONCLUSION

The rupture of ovarian aneurysm can occur during the perinatal period, although it has not been widely understood among obstetricians. Multiparity and hypertensive disorder of pregnancy might be risk factors for the rupture of an ovarian aneurysm. Early diagnosis and therapy, such as transcatheter arterial embolization in preparation for an emergency laparotomy, are crucially important for the management of this fatal disease.

Site-specific genetic and functional signatures of aortic endothelial cells at aneurysm predilection sites in healthy and AngII ApoE-/- mice

Aortic aneurysm is characterized by a pathological dilation at specific predilection sites of the vessel and potentially results in life-threatening vascular rupture. Herein, we established a modified "Häutchen method" for the local isolation of endothelial cells (ECs) from mouse aorta to analyze their spatial heterogeneity and potential role in site-specific disease development. When we compared ECs from aneurysm predilection sites of healthy mice with adjacent control segments we found regulation of genes related to extracellular matrix remodeling, angiogenesis and inflammation, all pathways playing a critical role in aneurysm development. We also detected enhanced cortical stiffness of the endothelium at these sites. Gene expression of ECs from aneurysms of the AngII ApoE-/- model when compared to sham animals mimicked expression patterns from predilection sites of healthy animals. Thus, this work highlights a striking genetic and functional regional heterogeneity in aortic ECs of healthy mice, which defines the location of aortic aneurysm formation in disease.

Iron Overload and Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is a chronic vascular degenerative disease characterized by progressive segmental dilation of the abdominal aorta. The rupture of an AAA represents a leading cause of death in cardiovascular diseases. Despite numerous experimental and clinical studies examining potential drug targets and therapies, currently there are no pharmaceutical treatment to prevent AAA growth and rupture. Iron is an essential element in almost all living organisms and has important biological functions. Epidemiological studies have indicated that both iron deficiency and overload are associated with adverse clinical outcomes, particularly an increased risk of cardiovascular events. Recent evidence indicates that iron overload is involved in the pathogenesis of abdominal aortic aneurysms. In this review, we provide an overview of the role of iron overload in AAA progression and explore its potential pathological mechanisms. Although the exact molecular mechanisms of iron overload in the development of AAA remain to be elucidated, the inhibition of iron deposition may offer a promising strategy for preventing these aneurysms.

Differential effects of angiotensin II and aldosterone on human neutrophil adhesion and concomitant secretion of proteins, free amino acids and reactive oxygen and nitrogen species

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

Highly sensitive magnetic particle imaging of abdominal aortic aneurysm NETosis with anti-Ly6G iron oxide nanoparticles

Abdominal aortic aneurysms (AAA) are a significant health concern in developed countries due to their considerable mortality rate. The crucial factor of the progression of AAA is the release of neutrophils and neutrophil extracellular traps (NETs). Magnetic particle imaging (MPI) is a new imaging technique that offers the capability to detect superparamagnetic iron oxide nanoparticles (SPION) with exceptional sensitivity. We aimed to investigate the functional imaging of MPI for the detection and monitoring of neutrophil infiltration within AAA. A novel multimodal imaging agent targeting neutrophils, PEG-Fe3O4-Ly6G-Cy7 nanoparticles (Ly6G NPs), were designed by coupling Fe3O4 nanoparticles with Ly6G antibodies and Cy7. The targeting and sensitivity of Ly6G NPs were assessed using MPI and fluorescence imaging (FLI) in the AAA mouse model. After the inhibition of NETosis, the degree of neutrophil infiltration and AAA severity were assessed using MPI with Ly6G NPs. Ly6G NPs accurately localized and quantitatively analyzed AAA lesion sites in mice using MPI/FLI/CT. Compared to the control group, elevated MPI and FLI signal intensities were detected at the abdominal aortic lesion site, and neutrophil infiltration and NETs accumulation were detected by histological analysis in the AAA models. After the inhibition of NETs accumulation in vivo, pathological damage in the abdominal aorta was significantly reduced, along with a decrease in the accumulation of Ly6G NPs and MPI signals. This multimodal MPI strategy revealed that nanoparticles targeting Ly6G can be used to detect neutrophil infiltration within AAA and monitor AAA severity.

Myeloid-Specific Thrombospondin-1 Deficiency Exacerbates Aortic Rupture via Broad Suppression of Extracellular Matrix Proteins

Rationale

Rupture of abdominal aortic aneurysms (AAA) is associated with high mortality. However, the precise molecular and cellular drivers of AAA rupture remain elusive. Our prior study showed that global and myeloid-specific deletion of matricellular protein thrombospondin-1 (TSP1) protects mice from aneurysm formation primarily by inhibiting vascular inflammation.

Objective

To investigate the cellular and molecular mechanisms that drive AAA rupture by testing how TSP1 deficiency in different cell populations affects the rupture event.

Methods and Results

We deleted TSP1 in endothelial cells and macrophages --- the major TSP1-expressing cells in aneurysmal tissues ---- by crossbreeding Thbs1 flox/flox mice with VE-cadherin Cre and Lyz2-cre mice, respectively. Aortic aneurysm and rupture were induced by angiotensin II in mice with hypercholesterolemia. Myeloid-specific Thbs1 knockout, but not endothelial-specific knockout, increased the rate of lethal aortic rupture by more than 2 folds. Combined analyses of single-cell RNA sequencing and histology showed a unique cellular and molecular signature of the rupture-prone aorta that was characterized by a broad suppression in inflammation and extracellular matrix production. Visium spatial transcriptomic analysis on human AAA tissues showed a correlation between low TSP1 expression and aortic dissection.

Conclusions

TSP1 expression by myeloid cells negatively regulates aneurysm rupture, likely through promoting the matrix repair phenotypes of vascular smooth muscle cells thereby increasing the strength of the vascular wall.

The Impact of COVID-19 Infection on Abdominal Aortic Aneurysms: Mechanisms and Clinical Implications

Background: The COVID-19 virus not only has significant pathogenicity but also influences the progression of many diseases, altering patient prognosis. Cardiovascular diseases, particularly aortic aneurysms, are among the most life-threatening conditions. Main Idea: COVID-19 infection is reported to accelerate the progression of abdominal aortic aneurysms (AAAs) and increase the risk of rupture; however, a comprehensive understanding of the underlying mechanisms remains elusive. This article primarily reviews the relevant foundational research, focusing on disruptions in the renin-angiotensin-aldosterone system (RAAS), immune system activation, and coagulation disorders. Furthermore, we summarize related clinical research, including the epidemiology of aortic aneurysms during the pandemic and specific case studies. Conclusion: COVID-19 infection can influence the onset and progression of aortic aneurysms by affecting the RAAS, triggering inflammation and immune dysregulation in the arterial wall, and inducing a hypercoagulation state. It is crucial to comprehensively understand the impact of pandemic viral infections on aortic diseases at the foundational and clinical levels, thereby identifying potential preventative or therapeutic approaches and preparing for potential future outbreaks.

Therapeutic potential of natural products and underlying targets for the treatment of aortic aneurysm

Aortic aneurysm is a vascular disease characterized by irreversible vasodilatation that can lead to dissection and rupture of the aortic aneurysm, a life-threatening condition. Thoracic aortic aneurysm (TAA) and abdominal aortic aneurysm (AAA) are two main types. The typical treatments for aortic aneurysms are open surgery and endovascular aortic repair, which are only indicated for more severe patients. Most patients with aneurysms have an insidious onset and slow progression, and there are no effective drugs to treat this stage. The inability of current animal models to perfectly simulate all the pathophysiological states of human aneurysms may be the key to this issue. Therefore, elucidating the molecular mechanisms of this disease, finding new therapeutic targets, and developing effective drugs to inhibit the development of aneurysms are the main issues of current research. Natural products have been applied for thousands of years to treat cardiovascular disease (CVD) in China and other Asian countries. In recent years, natural products have combined multi-omics, computational biology, and integrated pharmacology to accurately analyze drug components and targets. Therefore, the multi-component and multi-target complexity of natural products have made them a potentially ideal treatment for multifactorial diseases such as aortic aneurysms. Natural products have regained popularity worldwide. This review provides an overview of the known natural products for the treatment of TAA and AAA and searches for potential cardiovascular-targeted natural products that may treat TAA and AAA based on various cellular molecular mechanisms associated with aneurysm development.

Assessing trans-endothelial transport of nanoparticles for delivery to abdominal aortic aneurysms

Abdominal aortic aneurysms (AAAs) are localized, rupture-prone expansions of the abdominal aorta wall. In this condition, structural extracellular matrix (ECM) proteins of the aorta wall, elastic fibers and collagen fibers, that impart elasticity and stiffness respectively, are slowly degraded by overexpressed matrix metalloproteinases (MMPs) following an injury stimulus. We are seeking to deliver therapeutics to the AAA wall using polymer nanoparticles (NPs) that are capable of stimulating on-site matrix regeneration and repair. This study aimed to determine how NP shape and size impacts endocytosis and transmigration past the endothelial cell (EC) layer from circulation into the medial layer of the AAA wall. First, rod-shaped NPs were shown to be created based mechanical stretching of PLGA NPs while embedded in a PVA film with longer rod-shaped NPs created based of the degree in which the PVA films are stretched. Live/dead assay reveals that our PLGA NPs are safe and do not cause cell death. Immunofluorescence staining reveal cytokine activation causes endothelial dysfunction in ECs by increasing expression of inflammatory marker Integrin αVβ3 and decreasing expression of adhesion protein vascular endothelial (VE)-cadherin. We showed this disruption enable greater EC uptake and translocation of NPs. Fluorescence studies demonstrate high endothelial transmigration and endocytosis with rod-shaped NPs in cytokine activated ECs compared to healthy control cells, arguing for the benefits of using higher aspect ratio (AR) NPs for accumulation at the aneurysm site. We also demonstrated that the mechanisms of NP transmigration across an activated EC layer depend on NP AR. These results show the potential of using shape as a modality for enhancing permeation of NPs into the aneurysm wall. These studies are also significance to understanding the mechanisms that are likely engaged by NPs for penetrating the endothelial lining of aneurysmal wall segments.

Demographical and Clinical Factors Predictive for Aortic Dilatation. When should we be Concerned about the Size?

Background

Thoracic aortic aneurysms are often an accidental finding and result from a degenerative process. Medical therapy includes pharmacological control of arterial hypertension and smoking cessation, that slows the growth of aneurysms. An association between the dilatation of the ascending and abdominal aorta has been already reported. The aim of the study was to identify possible demographic and clinical factors that may implicate further imaging diagnostics in patients with ascending aorta dilatation.

Methods

There were 181 (93 (53%) males and 88 (47%) females) patients with a median age of 54 (41-62) years who underwent cardiac magnetic resonance due to non-vascular diseases, were enrolled into retrospective analysis.

Results

Multivariable analysis revealed ascending aorta dilatation (odds ratios (OR) = 7.45, 95% confidence interval (CI): 1.98-28.0, p = 0.003) and co-existence of coronary artery disease (OR = 8.68, 95% CI: 2.15-35.1, p = 0.002) as significant predictors for thoracic descending aorta dilatation. In patients with abdominal aorta dilatation, the multivariable analysis showed a predictive value of ascending aortic dilatation (OR = 14.8, 95% CI: 2.36-92.8, p = 0.004) and age (OR = 1.04, 95% CI: 1.00-1.08, p = 0.027). In addition, cut-off values were established for age groups determining the risk of thoracic aorta dilatation over 49 years and abdominal aorta dilatation over 54 years.

Conclusions

The results of our analysis showed predictive factors, including ascending aorta dilatation and co-existence of coronary artery disease, particularly over 49 years of age for thoracic, while ascending aorta dilatation and age, particularly over 54 years, for abdominal aorta dilatation. These features may be considered to increase clinical vigilance in patients with aortic diameter abnormalities.

Association between metabolic dysfunction-associated fatty liver disease and abdominal aortic aneurysm

BACKGROUND AND AIMS

Abdominal aortic aneurysm (AAA) is the second most common aortic pathological manifestation. Metabolic dysfunction-associated fatty liver disease (MAFLD) has a wide impact on the cardiovascular system and may be a risk factor for AAA. The aim of this study was to investigate whether MAFLD is associated with the risk of AAA.

METHODS AND RESULTS

We used data from the prospective UK Biobank cohort study. MAFLD is defined as hepatic steatosis plus metabolic abnormality, type 2 diabetes, or overweight/obesity. AAA is collected by ICD-10 code. Cox regression was established to analyze the association between MAFLD and AAA. A total of 370203 participants were included; the average age of the participants was 56.7 ± 8.0 years, and 134649 (36.4 %) were diagnosed with MAFLD. During the 12.5 years of follow-up, 1561 (0.4 %) participants developed AAA. After fully adjusting for confounding factors, individuals with MAFLD had a significantly increased risk of AAA (HR 1.521, 95 % CI 1.351-1.712, p < 0.001). Importantly, the risk of AAA increases with the severity of MAFLD as assessed by fibrosis scores. These associations were consistent according to sex, weight, and alcohol consumption but weaker in elderly or diabetics (P for interaction <0.05). The association between the MAFLD phenotype and AAA was independent of the polygenic risk score. Additionally, MAFLD was not associated with thoracic aortic aneurysm or aortic dissection events.

CONCLUSIONS

There was a significant relationship between MAFLD and AAA. These findings strongly recommend early prevention of AAA by intervening in MAFLD.

Identification of abdominal aortic aneurysm subtypes based on mechanosensitive genes

BACKGROUND

Rupture of abdominal aortic aneurysm (rAAA) is a fatal event in the elderly. Elevated blood pressure and weakening of vessel wall strength are major risk factors for this devastating event. This present study examined whether the expression profile of mechanosensitive genes correlates with the phenotype and outcome, thus, serving as a biomarker for AAA development.

METHODS

In this study, we identified mechanosensitive genes involved in AAA development using general bioinformatics methods and machine learning with six human datasets publicly available from the GEO database. Differentially expressed mechanosensitive genes (DEMGs) in AAAs were identified by differential expression analysis. Molecular biological functions of genes were explored using functional clustering, Protein-protein interaction (PPI), and weighted gene co-expression network analysis (WGCNA). According to the datasets (GSE98278, GSE205071 and GSE165470), the changes of diameter and aortic wall strength of AAA induced by DEMGs were verified by consensus clustering analysis, machine learning models, and statistical analysis. In addition, a model for identifying AAA subtypes was built using machine learning methods.

RESULTS

38 DEMGs clustered in pathways regulating 'Smooth muscle cell biology' and 'Cell or Tissue connectivity'. By analyzing the GSE205071 and GSE165470 datasets, DEMGs were found to respond to differences in aneurysm diameter and vessel wall strength. Thus, in the merged datasets, we formally created subgroups of AAAs and found differences in immune characteristics between the subgroups. Finally, a model that accurately predicts the AAA subtype that is more likely to rupture was successfully developed.

CONCLUSION

We identified 38 DEMGs that may be involved in AAA. This gene cluster is involved in regulating the maximum vessel diameter, degree of immunoinflammatory infiltration, and strength of the local vessel wall in AAA. The prognostic model we developed can accurately identify the AAA subtypes that tend to rupture.

Angiotensin II constricts mouse iliac arteries: possible mechanism for aortic aneurysms

Abdominal aortic aneurysms (AAA) result from maladaptive remodeling of the vascular wall and reduces structural integrity. Angiotensin II (AngII) infusion has become a standard laboratory model for studying AAA initiation and progression. We determined the different vasoactive responses of various mouse arteries to Ang II. Ex vivo isometric tension analysis was conducted on 18-week-old male C57BL/6 mice (n = 4) brachiocephalic arteries (BC), iliac arteries (IL), and abdominal (AA) and thoracic aorta (TA). Arterial rings were mounted between organ hooks, gently stretched and an AngII dose response was performed. Rings were placed in 4% paraformaldehyde for immunohistochemistry analysis to quantify peptide expression of angiotensin type 1 (AT1R) and 2 receptors (AT2R) in the endothelium, media, and adventitia. Results from this study demonstrated vasoconstriction responses in IL were significantly higher at all AngII doses when compared to BC, and TA and AA responses (maximum constriction-IL: 68.64 ± 5.47% vs. BC: 1.96 ± 1.00%; TA: 3.13 ± 0.16% and AA: 2.75 ± 1.77%, p < 0.0001). Expression of AT1R was highest in the endothelium of IL (p < 0.05) and in the media and (p < 0.05) adventitia (p < 0.05) of AA. In contrast, AT2R expression was highest in endothelium (p < 0.05), media (p < 0.01, p < 0.05) and adventitia of TA. These results suggest that mouse arteries display different vasoactive responses to AngII, and the exaggerated response in IL arteries may play a role during AAA development.

Nicotine Potentially Alters Endothelial Inflammation and Cell Adhesion via LGALS9

BACKGROUND

The endothelial cell layer is essential for the maintenance of various blood vessel functions. Major risk factors for endothelial dysfunction that contribute to aortic pathologies such as abdominal aortic aneurysm (AAA) and aortic dissection (AD) include smoking tobacco cigarettes and hypertension. This study explores the effects of nicotine (Nic) and angiotensin II (Ang II) on human aortic endothelial cells (HAoECs) at a transcriptional level.

METHODS

HAoECs were exposed to 100 nM Nic and/or 100 nM Ang II. RNA sequencing (RNA-Seq) was performed to identify regulated genes following exposure. Results were validated applying RT-qPCR. GeneMANIA was used to perform in silico analysis aiming to identify potential downstream interacting genes in inflammatory, cell-adhesion, endothelial cell proliferation, and coagulation pathways.

RESULTS

RNA-Seq identified LGALS9 (Galectin-9) as being potentially regulated following Nic exposure, while subsequent RT-qPCR experiments confirmed the transcriptional regulation (p < 0.05). Subsequent in silico analysis identified potential candidate genes for interacting with LGALS9 in different gene sets. Of the top 100 genes potentially interacting with LGALS9, 18 were inflammatory response genes, 28 were involved in cell adhesion, 2 in cell proliferation, and 6 in coagulation.

CONCLUSION

Nic exposure of HAoECs causes a significant increase in LGALS9 at a transcriptional level. LGALS9 itself may serve as key regulator for essential endothelial cell processes via interfering with various signaling pathways and may thus represent a potentially novel target in the pathogenesis of aortic pathologies.

The protective effects of pirfenidone in preventing abdominal aortic aneurysm formation

Vascular endothelial growth factor (VEGF)-mediated angiogenesis participates in the initiation and progression of abdominal aortic aneurysm (AAA). Pirfenidone is a compound that has anti-inflammatory and antioxidant properties and suppresses angiogenesis. Pirfenidone targets the extracellular matrix (ECM) and has therapeutic effects on fibrotic diseases. Therefore, we speculated that pirfenidone might have meaningful therapeutic effects in AAA, and the current study was designed to investigate this capacity. An AAA model was constructed in mice using a long-term injection of angiotensin II (Ang II), followed by a 28-day administration of 200 mg/kg/day pirfenidone. Increased maximal external diameter of the abdominal artery, promoted levels of VEGF-A and its receptor VEGF-R2, upregulated matrix metallopeptidases (MMP)-2 and MMP-9, and elevated release of pro-inflammatory cytokines were observed in AAA mice, which were extremely repressed by 200 mg/kg pirfenidone. Human aortic endothelial cells (HAECs) were stimulated with Ang II for 1 day, in the presence or absence of pirfenidone (100 nM). Elevated expression of VEGF-A and VEGF-R2, facilitated proliferation, increased tube formation ability, and upregulated MMP-2 and MMP-9 were observed in Ang II-stimulated HAECs, all of which were significantly rescued by 100 nM pirfenidone. Finally, the elevated levels of myeloid differentiation primary response 88 and phosphorylated nuclear factor-kappa-B subunit p65 observed in Ang II-stimulated HAECs were repressed by pirfenidone. Collectively, pirfenidone alleviated AAA by inhibiting ECM degradation and ameliorating endothelial dysfunction.

Irisin: A Potentially Fresh Insight into the Molecular Mechanisms Underlying Vascular Aging

Aging is a natural process that affects all living organisms, including humans. Aging is a complex process that involves the gradual deterioration of various biological processes and systems, including the cardiovascular system. Vascular aging refers to age-related changes in blood vessels. These changes can increase the risk of developing cardiovascular diseases, such as hypertension, atherosclerosis, and stroke. Recently, an exercise-induced muscle factor, irisin, was found to directly improve metabolism and regulate the balance of glucolipid metabolism, thereby counteracting obesity and insulin resistance. Based on a growing body of evidence, irisin modulates vascular aging. Adenosine monophosphate-activated protein kinase (AMPK) serves as a pivotal cellular energy sensor and metabolic modulator, acting as a central signaling cascade to coordinate various cellular processes necessary for maintaining vascular homeostasis. The vascular regulatory effects of irisin are closely intertwined with its interaction with the AMPK pathway. In conclusion, understanding the molecular processes used by irisin to regulate changes in vascular diseases caused by aging may inspire the development of techniques that promote healthy vascular aging. This review sought to describe the impact of irisin on the molecular mechanisms of vascular aging, including inflammation, oxidative stress, and epigenetics, from the perspective of endothelial cell function and vascular macroregulation, and summarize the multiple signaling pathways used by irisin to regulate vascular aging.

Disturbed hemodynamics and oxidative stress interaction in endothelial dysfunction and AAA progression: Focus on Nrf2 pathway

Hemodynamic shear stress is one of the major factors that are involved in the pathogenesis of many cardiovascular diseases including atherosclerosis and abdominal aortic aneurysm (AAA), through its modulatory effect on the endothelial cell's redox homeostasis and mechanosensitive gene expression. Among important mechanisms, oxidative stress, endoplasmic reticulum stress activation, and the subsequent endothelial dysfunction are attributed to disturbed blood flow and low shear stress in the vascular curvature and bifurcations which are considered atheroprone regions and aneurysm occurrence spots. Many pathways were shown to be involved in AAA progression. Of particular interest from recent findings is, the (Nrf2)/Keap-1 pathway, where Nrf2 is a transcription factor that has antioxidant properties and is strongly associated with several CVDs, yet, the exact mechanism by which Nrf2 alleviates CVDs still to be elucidated. Nrf2 expression is closely affected by shear stress and was shown to participate in AAA. In the current review paper, we discussed the link between disturbed hemodynamics and its effect on Nrf2 as a mechanosensitive gene and its role in the development of endothelial dysfunction which is linked to the progression of AAA.

Colchicine protects against the development of experimental abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is characterized by at least 1.5-fold enlargement of the infrarenal aorta, a ruptured AAA is life-threatening. Colchicine is a medicine used to treat gout and familial Mediterranean fever, and recently, it was approved to reduce the risk of cardiovascular events in adult patients with established atherosclerotic disease. With an AAA mice model created by treatment with porcine pancreatic elastase (PPE) and β-aminopropionitrile (BAPN), this work was designed to explore whether colchicine could protect against the development of AAA. Here, we showed that colchicine could limit AAA formation, as evidenced by the decreased total aortic weight per body weight, AAA incidence, maximal abdominal aortic diameter and collagen deposition. We also found that colchicine could prevent the phenotypic switching of vascular smooth muscle cells from a contractile to synthetic state during AAA. In addition, it was demonstrated that colchicine was able to reduce vascular inflammation, oxidative stress, cell pyroptosis and immune cells infiltration to the aortic wall in the AAA mice model. Finally, it was proved that the protective action of colchicine against AAA formation was mainly mediated by preventing immune cells infiltration to the aortic wall. In summary, our findings demonstrated that colchicine could protect against the development of experimental AAA, providing a potential therapeutic strategy for AAA intervention in the clinic.

Promising Novel Therapies in the Treatment of Aortic and Visceral Aneurysms

Aortic and visceral aneurysms affect large arterial vessels, including the thoracic and abdominal aorta, as well as visceral arterial branches, such as the splenic, hepatic, and mesenteric arteries, respectively. Although these clinical entities have not been equally researched, it seems that they might share certain common pathophysiological changes and molecular mechanisms. The yet limited published data, with regard to newly designed, novel therapies, could serve as a nidus for the evaluation and potential implementation of such treatments in large artery aneurysms. In both animal models and clinical trials, various novel treatments have been employed in an attempt to not only reduce the complications of the already implemented modalities, through manufacturing of more durable materials, but also to regenerate or replace affected tissues themselves. Cellular populations like stem and differentiated vascular cell types, large diameter tissue-engineered vascular grafts (TEVGs), and various molecules and biological factors that might target aspects of the pathophysiological process, including cell-adhesion stabilizers, metalloproteinase inhibitors, and miRNAs, could potentially contribute significantly to the treatment of these types of aneurysms. In this narrative review, we sought to collect and present relevant evidence in the literature, in an effort to unveil promising biological therapies, possibly applicable to the treatment of aortic aneurysms, both thoracic and abdominal, as well as visceral aneurysms.

METTL3-METTL14 complex induces necroptosis and inflammation of vascular smooth muscle cells via promoting N6 methyladenosine mRNA methylation of receptor-interacting protein 3 in abdominal aortic aneurysms

Abdominal aortic aneurysms (AAA) have the highest incidence and rupture rate of all aortic aneurysms. The N6 methyladenosine (m6A) modification is closely associated with angiotensin (Ang II)-induced aortic diseases. This study aimed to identify whether the m6A writer METTL3/METTL4 regulates rip3 mRNA expression in AAA. To induce the mouse AAA model, apolipoprotein E-deficient (ApoE-/-) mice were subcutaneously infused with Ang II, and C57BL/6 mice were infused with type I elastase. Vascular smooth muscle cells (VSMCs) were induced with Ang II. Necroptosis was detected using an Annexin V-FITC/PI apoptosis detection kit, and ELISA assays measured inflammatory cytokines. The RNA immunoprecipitation-qPCR determined the methylated rip3 mRNA level. The increased expressions of inflammatory factors, aortic adventitia injury, degradation of elastin, and CD68-positive cells suggested the successful establishment of mouse AAA models. In AAA aorta wall tissues, the m6A modification level and the expression of METTL3/METTL14 were elevated. In Ang II-induced VSMCs, necroptosis and inflammatory cytokines in the supernatants were increased. RNA immunoprecipitation and co-immunoprecipitation assays confirmed the binding between the METTL3-METTL14 complex and rip3 mRNA, the interaction between YTHDF3 and rip3 mRNA, and between the METTL3-METTL14 complex and SMAD2/3. Interference with METTL3/METTL14 attenuated VSMC necroptosis, inflammatory response, and the AAA pathological process in vivo. The METTL3-METTL14 complex, which was increased by the activation of the SMAD2/3, elevated the m6A modification of rip3 mRNA by promoting the binding between YTHDF3 and rip3 mRNA, thus contributing to the progression of AAA. The activation of SMAD2/3 in VSMCs of abdominal aortic wall tissues is stimulated by Ang II. Subsequently, it promotes METTL3 METTL14 complex mediated m6A modification of rip3 mRNA. Meanwhile, the level of rip3 mRNA becomes more stable under the m6A reader of YTHDF3, which increases the protein level of RIP3 and further induces VSMC necroptosis. In addition, cell debris induces inflammatory factors in neighboring VSMCs and recruit monocytes/macrophages to the lesion.

Single-cell RNA sequencing provides novel insights to pathologic pathways in abdominal aortic aneurysm

There is gaining popularity in the use of single-cell technology and analysis in studying the pathogenesis of abdominal aortic aneurysm (AAA). As there are no current pharmacologic therapies for impeding aneurysm growth or preventing AAA rupture, identifying key pathways involved in AAA formation is critical for the development of future therapies. Single-cell RNA sequencing (scRNA-seq) technology provides an unbiased and global view of transcriptomic characteristics within each of the major cell types in aneurysmal tissues. In this brief review, we examine the current literature utilizing scRNA-seq for the analysis of AAA and discuss trends and future utility of this technology.

Perspective of SGLT2i in the Treatment of Abdominal Aortic Aneurysms

ABSTRACT

The incidence of abdominal aortic aneurysm (AAA) in the elderly is increasing year by year with high mortality. Current treatment is mainly through surgery or endovascular intervention, which is not sufficient to reduce future risk. Therefore, we still need to find an effective conservative measure as an adjunct therapy or early intervention to prevent AAA progression. Traditional therapeutic agents, such as β-receptor blockers, calcium channel blockers, and statins, have been shown to have limited effects on the growth of AAA. Recently, sodium-glucose cotransport proteins inhibitors (SGLT2is), a new class hypoglycemic drug, have shown outstanding beneficiary effects on cardiovascular diseases by plasma volume reduction, vascular tone regulation, and various unidentified mechanisms. It has been demonstrated that SGLT2i is abundantly expressed in the aorta, and some studies also showed promising results of SGLT2i in treating animal AAA models. This article aims to summarize the recent progress of AAA studies and look forward to the application of SGLT2i in AAA treatment for early intervention or adjunct therapy after surgical repair or stent graft.

The mechanism and therapy of aortic aneurysms

Aortic aneurysm is a chronic aortic disease affected by many factors. Although it is generally asymptomatic, it poses a significant threat to human life due to a high risk of rupture. Because of its strong concealment, it is difficult to diagnose the disease in the early stage. At present, there are no effective drugs for the treatment of aneurysms. Surgical intervention and endovascular treatment are the only therapies. Although current studies have discovered that inflammatory responses as well as the production and activation of various proteases promote aortic aneurysm, the specific mechanisms remain unclear. Researchers are further exploring the pathogenesis of aneurysms to find new targets for diagnosis and treatment. To better understand aortic aneurysm, this review elaborates on the discovery history of aortic aneurysm, main classification and clinical manifestations, related molecular mechanisms, clinical cohort studies and animal models, with the ultimate goal of providing insights into the treatment of this devastating disease. The underlying problem with aneurysm disease is weakening of the aortic wall, leading to progressive dilation. If not treated in time, the aortic aneurysm eventually ruptures. An aortic aneurysm is a local enlargement of an artery caused by a weakening of the aortic wall. The disease is usually asymptomatic but leads to high mortality due to the risk of artery rupture.

Circular RNAs as a Diagnostic and Therapeutic Target in Cardiovascular Diseases

Circular RNAs (circRNAs) are a family of noncoding RNAs (ncRNAs) that are endogenous and widely distributed in different species, performing several functions, mainly their association with microRNAs (miRNAs) and RNA-binding proteins. CVDs remain the leading cause of death worldwide; therefore, the development of new therapies and strategies, such as gene therapies or nonpharmacological therapies, with low cost, such as physical exercise, to alleviate these diseases is of extreme importance for society. With increasing evidence of ncRNA participating in the progression of CVDs, several studies have reported these RNAs as promising targets for diagnosis and treatment. There are several studies of CVDs and the role of miRNAs and lncRNAs; however, little is known about the new class of RNAs, called circRNAs, and CVDs. In this mini review, we focus on the mechanisms of circRNAs and CVDs.

Single-cell transcriptome in silico analysis reveals conserved regulatory programs in macrophages/monocytes of abdominal aortic aneurysm from multiple mouse models and human

Abdominal aortic aneurysm (AAA) is a life-threatening disease and there is currently a lack of effective treatment to prevent it rupturing. ScRNA-seq studies of AAA are still lacking. In the study, we analyzed the published AAA scRNA-seq datasets from the mouse elastase-induced model, CaCl₂ treatment model, Ang II-induced model and human by using bioinformatic approaches and in silico analysis. A total of 26 cell clusters were obtained and 11 cell types were identified from multiple mouse AAA models. Also, the proportion of Mφ/Mo increased in the AAA group and Mφ/Mo was divided into seven subtypes. There were significant differences in transcriptional regulation patterns of Mφ/Mo in different AAA models. The enrichment pathways of upregulated or downregulated genes from Mφ/Mo in the three mouse datasets were different. The actived regulons of Mφ/Mo had strong specificity and the repressed regulons showed high consistency. The co-upregulated genes as well as actived regulons and co-downregulated genes as well as repressed regulons were closely correlated and formed regulatory networks. Mφ/Mo from human AAA dataset was divided into five subtypes. The proportion of three macrophage subpopulations increased but the proportion of two monocyte subpopulations decreased. In the AAA group, the upregulated or downregulated genes of Mφ/Mo were enriched in different pathways. After further analyzing the genes in Mφ/Mo of both mouse and human scRNA-seq datasets, two genes were upregulated in the four datasets, IL-1B and THBS1. In conclusion, in silico analysis of scRNA-seq revealed that Mφ/Mo and their regulatory related genes as well as interaction networks played an important role in the pathogenesis of AAA.

Mechanosignals in abdominal aortic aneurysms

Cumulative evidence has shown that mechanical and frictional forces exert distinct effects in the multi-cellular aortic layers and play a significant role in the development of abdominal aortic aneurysms (AAA). These mechanical cues collectively trigger signaling cascades relying on mechanosensory cellular hubs that regulate vascular remodeling programs leading to the exaggerated degradation of the extracellular matrix (ECM), culminating in lethal aortic rupture. In this review, we provide an update and summarize the current understanding of the mechanotransduction networks in different cell types during AAA development. We focus on different mechanosensors and stressors that accumulate in the AAA sac and the mechanotransduction cascades that contribute to inflammation, oxidative stress, remodeling, and ECM degradation. We provide perspectives on manipulating this mechano-machinery as a new direction for future research in AAA.

Protection of diabetes in aortic abdominal aneurysm: Are antidiabetics the real effectors?

Aortic aneurysms, including abdominal aortic aneurysms (AAAs), is the second most prevalent aortic disease and represents an important cause of death worldwide. AAA is a permanent dilation of the aorta on its infrarenal portion, pathologically associated with oxidative stress, proteolysis, vascular smooth muscle cell loss, immune-inflammation, and extracellular matrix remodeling and degradation. Most epidemiological studies have shown a potential protective role of diabetes mellitus (DM) on the prevalence and incidence of AAA. The effect of DM on AAA might be explained mainly by two factors: hyperglycemia [or other DM-related factors such as insulin resistance (IR)] and/or by the effect of prescribed DM drugs, which may have a direct or indirect effect on the formation and progression of AAAs. However, recent studies further support that the protective role of DM in AAA may be attributable to antidiabetic therapies (i.e.: metformin or SGLT-2 inhibitors). This review summarizes current literature on the relationship between DM and the incidence, progression, and rupture of AAAs, and discusses the potential cellular and molecular pathways that may be involved in its vascular effects. Besides, we provide a summary of current antidiabetic therapies which use could be beneficial for AAA.

Towards Precritical Medical Therapy of the Abdominal Aortic Aneurysm

Pharmacotherapy for abdominal aortic aneurysm (AAA) can be useful for prevention, especially in people at higher risk, for slowing down AAA progression, as well as for post-surgery adjuvant treatment. Our review focuses on novel pharmacotherapy approaches targeted towards slowing down progression of AAA, known also as secondary prevention therapy. Guidelines for AAA are not specific to slow down the expansion rate of an abdominal aortic aneurysm, and therefore no medical therapy is recommended. New ideas are urgently needed to develop a novel medical therapy. We are hopeful that in the future, pharmacologic treatment will play a key role in the prevention and treatment of AAA.

Aortic Aneurysm and Dissection: Heterogeneity and Molecular Mechanisms

Aortic aneurysms and dissections (AAD) are devastating aortic diseases with high risks for aortic rupture, leading to uncontrolled bleeding and death [...].

The role of phosphoinositide 3-kinases in immune-inflammatory responses: potential therapeutic targets for abdominal aortic aneurysm

The pathogenesis of abdominal aortic aneurysm (AAA) includes inflammatory responses, matrix metalloproteinases (MMPs) degradation, VSMC apoptosis, oxidative stress, and angiogenesis, among which the inflammatory response plays a key role. At present, surgery is the only curing treatment, and no effective drug can delay AAA progression in clinical practice. Therefore, searching for a signaling pathway related to the immune-inflammatory response is an essential direction for developing drugs targeting AAA. Recent studies have confirmed that the PI3K family plays an important role in many inflammatory diseases and is involved in regulating various cellular functions, especially in the immune-inflammatory response. This review focuses on the role of each isoform of PI3K in each stage of AAA immune-inflammatory response, making available explorations for a deeper understanding of the mechanism of inflammation and immune response during the formation and development of AAA.