Aortic Aneurysm Formation Research Articles

Montelukast inhibits abdominal aortic aneurysm formation in mice via activating the AMPK/mTOR signalling pathway

ObjectiveTo investigate the mechanism by which Montelukast inhibits abdominal aortic aneurysm (AAA) formation through the AMPK/mTOR signaling pathway in mice.MethodsMice were randomly assigned to the Normal group, Model group, Montelukast group, and Montelukast + compound C (C.C) group. The Model, Montelukast, and Montelukast + C.C groups were induced with AAA by continuous infusion of 1000 ng/kg/min of Ang II. The Montelukast group received daily oral administration of 10 mg/kg Montelukast, while the Montelukast + C.C group received 10 mg/kg Montelukast and 10 mg/kg C.C orally for 28 days. Abdominal aortas were isolated, and their diameters and AAA occurrence were measured using a micrometer. Histological analysis was performed using Hematoxylin-Eosin (HE) staining to assess the morphological changes. TUNEL staining was conducted to measure cell apoptosis levels in the abdominal aortas. Western Blot was employed to evaluate protein expressions of Bax, Bcl-2, MMP-2, MMP-9, α1-AT, p-AMPK, AMPK, p-mTOR, mTOR in the abdominal aortic tissues. qRT-PCR was used to assess the expression of IL-6, TNF-α, IFN-γ in the mouse abdominal aortas.ResultsCompared to the Normal group, the Model group showed significantly increased abdominal aortic diameter, AAA occurrence, TUNEL positivity, Bax/Bcl-2 ratio, IL-6, TNF-α, IFN-γ, MMP-2, MMP-9, p-mTOR/mTOR, and decreased α1-AT, p-AMPK/AMPK (P < 0.05). The Montelukast group exhibited significant decreases in abdominal aortic diameter, AAA occurrence, TUNEL positivity, Bax/Bcl-2 ratio, IL-6, TNF-α, IFN-γ, MMP-2, MMP-9, p-mTOR/mTOR, and increases in α1-AT, p-AMPK/AMPK compared to the Model group (P < 0.05). The Montelukast + C.C group showed opposite trends compared to the Montelukast group (P < 0.05). The Normal group exhibited intact abdominal aortic wall structure with orderly arranged cells. The Model group showed thickened aortic walls, plaque formation, and inflammatory cell infiltration. The Montelukast group demonstrated reduced aortic wall thickening, approaching a morphology closer to the Normal group. The Montelukast + C.C group exhibited a morphology between the Model and Montelukast groups.ConclusionMontelukast can inhibit AAA formation in mice, possibly through the downregulation of cell apoptosis, inflammatory response, and matrix metalloproteinase levels via the AMPK/mTOR signaling pathway.

Genetic Manipulation of Caveolin-1 in a Transgenic Mouse Model of Aortic Root Aneurysm: Sex-Dependent Effects on Endothelial and Smooth Muscle Function

Marfan syndrome (MFS) is a systemic connective tissue disorder stemming from mutations in the gene encoding Fibrillin-1 (Fbn1), a key extracellular matrix glycoprotein. This condition manifests with various clinical features, the most critical of which is the formation of aortic root aneurysms. Reduced nitric oxide (NO) production due to diminished endothelial nitric oxide synthase (eNOS) activity has been linked to MFS aortic aneurysm pathology. Caveolin-1 (Cav1), a structural protein of plasma membrane caveolae, is known to inhibit eNOS activity, suggesting its involvement in MFS aneurysm progression by modulating NO levels. In this study, we examined the role of Cav1 in aortic smooth muscle and endothelial function, aortic wall elasticity, and wall strength in male and female MFS mice (FBN1+/Cys1041Gly) by generating developing Cav1-deficient MFS mice (MFS/Cav1KO). Our findings reveal that Cav1 ablation leads to a pronounced reduction in aortic smooth muscle contraction in response to phenylephrine, attributable to an increase in NO production in the aortic wall. Furthermore, we observed enhanced aortic relaxation responses to acetylcholine in MFS/Cav1KO mice, further underscoring Cav1’s inhibitory impact on NO synthesis within the aorta. Notably, van Gieson staining and chamber myography analyses showed improved elastin fiber structure and wall strength in male MFS/Cav1KO mice, whereas these effects were absent in female counterparts. Cav1’s regulatory influence on aortic root aneurysm development in MFS through NO-mediated modulation of smooth muscle and endothelial function, with notable sex-dependent variations.

Disruption of PCSK9 Suppresses Inflammation and Attenuates Abdominal Aortic Aneurysm Formation.

Abdominal aortic aneurysm (AAA) is a chronic vascular inflammatory disease without effective medications. PCSK9 (proprotein convertase subtilisin/kexin 9), a serine protease from the proprotein convertase family, has recently been associated with AAA in human genome-wide association studies. However, its role in AAA is unknown. Transcriptional and histological expression of PCSK9 was examined in AAA tissues and healthy controls. The impact of PCSK9 deletion and inhibition on AAA formation was assessed in mice with hyperlipidemia and Ang II (angiotensin II) overproduction. AAA lesion morphology was assessed by tissue staining. MMP (matrix metalloproteinase) activity was evaluated by gelatin zymography, and leukocyte-vessel wall interaction was monitored by intravital microscopy. RNA sequencing was used to characterize the downstream signaling of PCSK9. PCSK9 expression was upregulated and colocalized with macrophages in human and mouse AAAs. Pcsk9 deletion attenuated AAA formation, improved survival, and decreased systemic inflammation, without altering circulating cholesterol levels. Pcsk9 deficiency reduced aortic infiltration of macrophages and elastin degradation, without affecting vascular smooth muscle cell apoptosis and proliferation. Mechanistically, PCSK9 was essential in leukocyte-endothelium adhesion and expression of proinflammatory cytokines and MMP9 by macrophages. RNA sequencing of stimulated macrophages revealed that Pcsk9 deficiency upregulated histone deacetylase SIRT1 (sirtuin-1) and suppressed NF-κB (nuclear factor-κB) inflammatory signaling. SIRT1 inhibition attenuated the proinflammatory actions of PCSK9. Furthermore, administration of PCSK9 small interfering RNA or antibody constrained AAA formation/progression and inhibited vascular inflammation. PCSK9 critically mediates macrophage inflammation and elastin degradation, promoting AAA formation. PCSK9 inhibitors bear a promise to curtail AAA, beyond being used as cholesterol-lowering drugs.

Abstract 4135035: Liver kinase B1 (LKB1) loss links vascular smooth muscle cell fate switch to aortic aneurysm formation

Background: Acquisition and maintenance of vascular smooth muscle cell (VSMC) fate are important for vascular development and homeostasis; however, little is known about the key determinant for VSMC fate and vascular homeostasis. Methods: Lkb1 flox/flox ; Tagln- Cre, Lkb1 flox /flox ; Myh11-Cre/ERT2 , and lineage tracing Lkb1 flox/flox ; Myh11-Cre/ERT2 ; ROSA mT/mG mice were generated to study the impact of Lkb1 on VSMC and vascular function in vivo . Single aortic cells isolated from wild-type and Lkb1 flox/flox ; Myh11-Cre/ERT2 mice were analyzed by single-cell RNA sequencing (sc-RNA seq). The dynamic changes of vascular morphology and VSMC fate were investigated using high-frequency ultrasound and various histological techniques. In addition, VSMC phenotype and molecular mechanisms were further explored by mouse arterial ring assay ex vivo , in cultured human aortic VSMC in vitro, and in human aneurysmal aortic tissues. Results: We found that SMC-specific Lkb1 ablation in Lkb1 flox/flox ; Tagln-Cre mice caused severe vascular abnormalities and embryonic lethality. SMC-specific deletion of Lkb1 in tamoxifen-inducible Lkb1 flox/flox ; Myh11-Cre/ERT2 mice spontaneously and progressively induced aortic/arterial dilation, aneurysm, rupture, and premature death. Sc-RNA seq and imaging-based lineage tracing showed that Lkb1 -deficient VSMCs transdifferentiated gradually from early modulated VSMCs to fibroblast-like and chondrocyte-like cells, leading to ossification and blood-vessel rupture. Moreover, we found that SMC-specific Lkb1 ablation resulted in decreased vascular contractility and hypotension in vivo . Mechanistically, Lkb1 regulates polypyrimidine tract binding protein 1 (Ptbp1) expression and controls alternative splicing of pyruvate kinase muscle (PKM) isoforms 1 and 2. Lkb1 loss in VSMC results in an increased PKM2/PKM1 ratio and alters the metabolic profile by promoting aerobic glycolysis. Treatment with PKM2 activator TEPP-46 rescues VSMC transformation and aortic dilation in Lkb1 flox/flox ; Myh11-Cre/ERT2 mice. Furthermore, we found that Lkb1 expression decreased in human aortic aneurysm tissue compared to control tissue, along with changes in markers of VSMC fate. Conclusions: Lkb1, via its regulation of Ptbp1-dependent alterative splicing of PKM, maintains VSMC in contractile states and sustains vascular homeostasis. Our findings have important implications for understanding the pathogenesis of aortic aneurysm.

Abstract 4137735: Chronic Oxidative Stress Induces Hypertension and Abdominal Aortic Aneurysm in Chemogenetic Mice Model

Background: Aortic aneurysms account for ~10,000 deaths annually in the USA. Oxidative stress is implicated in both abdominal (AAA) and thoracic (TAA) aneurysm formation, but the mechanisms are incompletely understood. We used a chemogenetic approach to modulate oxidative stress in the vascular wall by creating a transgenic mouse (DAAO-TG Tie2 ) that expresses yeast D-amino acid oxidase (DAAO) driven by the endothelial Tie2 promoter. DAAO generates the reactive oxygen species hydrogen peroxide from D-amino acids. Vascular tissues contain L-amino acids, so yeast DAAO is quiescent until DAAO-TG Tie2 mice are provided with D-amino acids. Here we characterize the cellular and molecular consequences of vascular oxidative stress in DAAO-TG Tie2 mice. Hypothesis: Chronic oxidative stress in the vascular wall causes arterial dysfunction. Aim: To characterize the phenotype of DAAO-TG Tie2 mice after oxidative stress induction in vascular endothelium. To identify the mechanisms whereby vascular oxidative stress causes arterial dysfunction and hypertension. Methods: Systolic blood pressure and aortic sonography were measured weekly in D-alanine-fed DAAO-TG Tie2 . Proteomic analyses were used to identify mechanistic targets, which were validated using biochemical and immunohistochemical methods. Results: D-alanine-fed DAAO-TG Tie2 mice develop systolic hypertension and abdominal but not thoracic aortic aneurysms; treated mice die in &gt;3 months with burst abdominal aortic aneurysms. Transgene expression is similar in abdominal and thoracic endothelium. Levels of oxidative stress markers (oxidized proteins, lipid, and DNA) were similar in thoracic and abdominal aorta. Proteomic analyses established phenotypic switching in abdominal but not thoracic aorta, and also revealed activation of the oxidant-activated kinase ASK1 and of the MAP kinase cascade in abdominal but not thoracic aorta. Immunoblot analyses showed a marked decrease in JNK1 phosphorylation by phosphatase DUSP3 and an increase in vascular KLF4, leading to phenotypic switching of contractile to synthetic VSMCs. Conclusion: Chronic chemogenetic oxidative stress induces hypertension and abdominal aortic aneurysm formation caused by KLF4-dependent VSMC phenotypic switching.

ANK Deficiency-Mediated Cytosolic Citrate Accumulation Promotes Aortic Aneurysm.

Disturbed metabolism and transport of citrate play significant roles in various pathologies. However, vascular citrate regulation and its potential role in aortic aneurysm (AA) development remain poorly understood. Untargeted metabolomics by mass spectrometry was applied to identify upregulated metabolites of the tricarboxylic acid cycle in AA tissues of mice. To investigate the role of citrate and its transporter ANK (progressive ankylosis protein) in AA development, vascular smooth muscle cell (VSMC)-specific Ank-knockout mice were used in both Ang II (angiotensin II)- and CaPO4-induced AA models. Citrate was abnormally increased in both human and murine aneurysmal tissues, which was associated with downregulation of ANK, a citrate membrane transporter, in VSMCs. The knockout of Ank in VSMCs promoted AA formation in both Ang II- and CaPO4-induced AA models, while its overexpression inhibited the development of aneurysms. Mechanistically, ANK deficiency in VSMCs caused abnormal cytosolic accumulation of citrate, which was cleaved into acetyl coenzyme A and thus intensified histone acetylation at H3K23, H3K27, and H4K5. Cleavage under target and tagmentation analysis further identified that ANK deficiency-induced histone acetylation activated the transcription of inflammatory genes in VSMCs and thus promoted a citrate-related proinflammatory VSMC phenotype during aneurysm diseases. Accordingly, suppressing citrate cleavage to acetyl coenzyme A downregulated inflammatory gene expression in VSMCs and restricted ANK deficiency-aggravated AA formation. Our studies define the pathogenic role of ANK deficiency-induced cytosolic citrate accumulation in AA pathogenesis and an undescribed citrate-related proinflammatory VSMC phenotype. Targeting ANK-mediated citrate transport may emerge as a novel diagnostic and therapeutic strategy in AA.

Inhibiting YAP1 reduced abdominal aortic aneurysm formation by suppressing adventitial fibroblast phenotype transformation and migration.

The adventitial fibroblast (AF) is the most abundant cell in the vascular adventitia, a few studies had confirmed that AF contributed to abdominal aortic aneurysm (AAA) development; YAP1 involved in several vascular diseases by promoting AF transformed to myofibroblast, the role of YAP1 in AAA is not clear yet. This study aims to determine whether YAP1 play a role in AAA process by regulating AF function. We found the expression of YAP1was significantly increased in aneurysm tissues of AAA patients compared to normal adjacent vascular tissues and mainly in adventitia. YAP1 also upregulated in elastase-induced and CaCl2-induced mice AAA model. Suppressed YAP1 function with YAP1 inhibitor-Verteporfin declined AAA incident rate remarkably in mice, and the collagen deposition in the adventitia was alleviated obviously. Afterwards, we studied the effect of YAP1 on the function of AF, Verteporfin was used to block YAP1 invitro, the process of AF transforming to myofibroblast and migration were almost completely eliminated after inhibiting YAP1 expression. This study demonstrated that YAP1 may play a key role in AAA development, inhibiting YAP1 significantly reduced AAA formation through suppressed the process of AF transformed to myofibroblast and migration.

Oral low-dose rapamycin treatment prevents aortic aneurysms in marfan mice

Abstract Background/Introduction Marfan syndrome (MFS) is a hereditary connective tissue disorder caused by fibrillin-1 (FBN1) gene mutations. Life-threatening complications are cardiovascular, e.g. thoracic aortic aneurysms and dissections. The pathophysiological cause is the increased release of transforming growth factor β-1 (TGF-β1) from the FBN1-deficient extracellular matrix (ECM) and structural disintegrity. Overactivation of the mechanistic target of rapamycin (mTOR) pathway has been demonstrated in the murine mgR/mgR model of MFS. Short-term administration of rapamycin significantly reduced aortic aneurysm formation and increased the life span in these mice. Purpose To assess the effect of an early continuous oral low-dose rapamycin treatment on the aortic aneurysm formation in the FBN1 hypomorphic mgR/mgR mouse model. Methods Male and female 3-4 week-old mgR/mgR mice were orally administered vehicle or rapamycin through diet (8mg/kg/KG) and sacrificed after 11 weeks. Rapamycin concentration was measured by liquid chromatography-mass spectrometry in whole blood. Aortic diameter was studied using echocardiography. Histopathological and immunofluorescence analyses were performed using aortic tissue sections and techniques. Results Blood rapamycin concentration following oral administration remained below detection level. Rapamycin normalized the aortic wall thickness and the diameter in female mgR/mgR mice to levels of the littermate control mice but not in male mgR/mgR mice. The circumferentially distributed elastin fibres remained significantly intact in sections of the ascending aorta of female mice. Echocardiography revealed that rapamycin-treated female mice stayed below a cut-off value for aortic aneurysms of 2 mm inner aortic diameter eight weeks after starting therapy. In contrast, vehicle-treated female animals already exceeded this value after five weeks. In female but not in male mice, the abundance of the mTOR downstream target phosphorylated ribosomal protein S6 was effectively suppressed by low-dose rapamycin up to levels detected in control animals. At the same time, extracellular matrix proteins like the proteoglycan aggrecan (ACAN) and the related chondroitin sulfate were significantly decreased in female mice. The abundance of ADAMTS5 transglutaminase-2 and xylosyltransferase-1, key enzymes involved in the turnover of proteoglycans and biosynthesis of glycosaminoglycan chains, was improved by the rapamycin treatment in female mice. No decrease in mTOR activity could be detected in male mgR/mgR animals. Here, the ACAN and chondroitin sulphate levels also remained at the level of the vehicle-treated animals. Conclusions Chronic low-dose rapamycin treatment reduced aneurysm formation only in female mgR/mgR mice, since the dose was too low for male mgR/mgR mice, by affecting the composition and organization of key ECM components essential for maintaining aortic homeostasis and mechanical properties.

Toll-Like Receptor 2 Attenuates the Formation and Progression of Angiotensin II-Induced Abdominal Aortic Aneurysm in ApoE−/− Mice

Introduction: We demonstrated Toll-like receptor (TLR) 4 in the pathogenesis of angiotensin II (AngII)-mediated abdominal aortic aneurysm (AAA) formation. Here, we study TLR2 in the AAA formation. Methods: Male ApoE−/− and ApoE−/−TLR2−/− mice were treated with AngII. Mice were injected with the TLR2 agonist Pam3CSK4. The incidence and severity of AAA were determined. MCP-1, MCP-5, RANTES, CXCL10, CCR5, and CXCR3 were analyzed. M1 and M2 macrophages in the aorta were detected by flow cytometry. Results: These studies demonstrated an increase in AAA formation in TLR2−/− mice and a decrease by Pam3CSK4. Pam3CSK4 decreased the ratio of M1/M2 and the levels of RANTES, CXCL10, CCR5, and CXCR3. Furthermore, Pam3CSK4 treatment 1 week following AngII retarded the progression of AAA. Conclusion: These data demonstrated a protective effect of TLR2 signaling on AAA in association with a decrease in the ratio of M1 to M2 macrophages and the expression of chemokines and their receptors. Furthermore, the treatment of Pam3CSK4 after AngII demonstrated a marked retardation of lesion progression. Given the fact that most AAA patients are detected late in the disease process, these findings suggest that TLR2 stimulation may play a therapeutic role in retarding disease progression.

Potential effects of a human milk oligosaccharide 6'-sialyllactose on angiotensin II-induced aortic aneurysm via p90RSK/TGF-β/SMAD2 signaling pathway.

The aberrant phenotypic transformation of vascular smooth muscle cells (VSMCs) is a key factor in the formation of aortic aneurysm (AA). This study aimed to explore theeffects of 6'-sialyllactose (6'-SL), a human milk oligosaccharide, on angiotensin II (Ang II)-induced VSMC dysfunction and AA formation both in vitro and in vivo. An AA model was established in male C57BL/6 mice challenged with Ang II via osmotic pumps and a lysyl oxidase inhibitor, β-aminopropionitrile (BAPN), in drinking water. The mice were administered with 6'-SL, FMK (a p90RSK inhibitor), or losartan (as a positive control). In vitro, VSMCs were pretreated with 6'-SL before Ang II stimulation. We found that p90RSK inhibition abolished Ang II/BAPN-induced thoracic AA and abdominal AA formation. Treatment with 100mg/kg 6'-SL significantly attenuated Ang II/BAPN-induced aortic dilatation. 6'-SL attenuated Ang II-induced collagen deposition, calcification, and immune cell accumulation. Consistently, 6'-SL downregulated p-p90RSK, p90RSK, and p-SMAD2, and mitigated VSMC contractility loss, as indicated by α-SMA expression in vivo. Interestingly, Ang II-induced transforming growth factor-beta (TGF-β) signaling pathway was suppressed by p90RSK inhibition in VSMCs. 6'-SL treatment significantly reduced TGF-β/SMAD2 targets, including dedifferentiation markers such asosteopontin and vimentin, and elastin degradation factors MMP2 and MMP9. Overexpression of p90RSK in VSMCs enhanced TGF-β and abrogated the effects of 6'-SL. Furthermore, 6'-SL co-treatment abolished high phosphate-induced calcification in vitro via p90RSK/TGF-β signaling pathway. Altogether, our findings suggest that 6'-SL could be a potential therapeutic candidate for protecting against Ang II-induced AA formation by inhibiting the p90RSK/TGF-β/SMAD2 signaling pathway.

Porphyromonas gingivalis GroEL accelerates abdominal aortic aneurysm formation by matrix metalloproteinase-2 SUMOylation in vascular smooth muscle cells: A novel finding for the activation of MMP-2.

Infection is a known cause of abdominal aortic aneurysm (AAA), and matrix metalloproteases-2 (MMP-2) secreted by vascular smooth muscle cells (SMCs) plays a key role in the structural disruption of the middle layer of the arteries during AAA progression. The periodontal pathogen Porphyromonas gingivalis is highly associated with the progression of periodontitis. GroEL protein of periodontal pathogens is an important virulence factor that can invade the body through either the bloodstream or digestive tract and is associated with numerous systemic diseases. Although P. gingivalis aggravates AAA by increasing the expression of MMP-2 in animal studies, the molecular mechanism through which P. gingivalis regulates the expression of MMP-2 is still unknown and requires further investigation. In this study, we first confirmed through animal experiments that P. gingivalis GroEL promotes MMP-2 secretion from vascular SMCs, thereby aggravating Ang II-induced aortic remodeling and AAA formation. In addition, rat vascular SMCs and A7r5 cells were used to investigate the underlying mechanisms in vitro. The results demonstrated that GroEL can promote the interaction between the K639 site of MMP-2 and SUMO-1, leading to MMP-2 SUMOylation, which inhibits the reoccurrence of non-K639-mediated monoubiquitylation. Hence, the monoubiquitylation-mediated lysosomal degradation of MMP-2 is inhibited, consequently promoting MMP-2 stability and production. SUMOylation may facilitate intra-endoplasmic reticulum (ER) and Golgi trafficking of MMP-2, thereby enhancing its transport capacity. In conclusion, this is the first report demonstrating the presence of a novel posttranslational modification, SUMOylation, in the MMP family, suggesting that P. gingivalis GroEL may exacerbate AAA formation by increasing MMP-2 production through SUMOylation in vascular SMCs. This study also provides a novel perspective on the role of SUMOylation in MMP-2-induced systemic diseases.

Eugenol restrains Angiotensin II-induced death, inflammation and ferroptosis of vascular smooth muscle cells by targeting STAT3/HMGB2 axis.

Eugenol has been found to inhibit a variety of disease processes, including abdominal aortic aneurysm (AAA) formation. However, the specific role and the underlying molecular mechanism of Eugenol in AAA progression need to be further revealed. Vascular smooth muscle cells (VSMCs) were pre-treated with Eugenol, followed by treated with Angiotensin II (Ang-II). VSMCs were transfected with HMGB2 siRNA or overexpression vector and treated with Ang-II to confirm the effect of HMGB2 on AAA progression. Cell proliferation and death were determined using cell counting kit 8 (CCK8) assay, 5-ethynyl-2'-deoxyuridine (EdU) assay and flow cytometry. Inflammatory factors were examined by ELISA. Fe2+, glutathione (GSH) and malondialdehyde (MDA) levels were tested to evaluate cell ferroptosis. The protein levels of ferroptosis-related markers, high mobility group box 2 (HMGB2) and STAT3 were measured using western blot. Human AAA tissues and normal abdominal aortic tissues were collected to detect HMGB2 mRNA expression by quantitative real-time PCR. The interaction between HMGB2 and STAT3 was confirmed by chromatin immunoprecipitation (ChIP) assay and dual-luciferase reporter assay. Eugenol enhanced VSMCs proliferation, while restrained Ang-II-induced death, inflammation and ferroptosis. HMGB2 was upregulated in AAA tissues and Ang-II-induced VSMCs, and Eugenol significantly decreased HMGB2 expression. HMGB2 knockdown reduced Ang-II-induced VSMCs death, inflammation and ferroptosis, Besides, HMGB2 overexpression abolished the effect of Eugenol on Ang-II-induced VSMCs injury. Transcription factor STAT3 bound to HMGB2 promoter region to increase its expression. In addition, Eugenol decreased STAT3 expression to regulate HMGB2. Eugenol could slow down the development of AAA, which might be achieved by regulating STAT3/HMGB2 axis.

Aortic aneurysm: Correlations with phenotypes associated with connective tissue dysplasia

An aortic aneurysm is a localized enlargement that exceeds the normal diameter of the vessel by 50 %, posing a risk due to the likelihood of rupture. The cause of aortic aneurysm, especially in young people, is connective tissue dysplasia, a condition characterized by defects in the assembly of collagen and elastin proteins, leading to changes in elastic properties and disruption of the formation of organs and their systems. The article presents data confirming the relationship between many morphological manifestations of connective tissue dysplasia (e.g., funnel-shaped deformation of the sternum, scoliosis of the thoracic spine, abdominal hernias, arterial tortuosity, striae of atypical localization) and the risk of aortic aneurysm formation. The literature suggests that the identified combinations of some external manifestations of connective tissue dysplasia deserve special attention and may be constitutional markers for the possible development of aortic aneurysm, which is a promising direction for further research in this area.

Inhibition of Endothelial Cell-Mediated Efferocytosis Promotes Abdominal Aortic Aneurysm Formation

Inhibition of Endothelial Cell-Mediated Efferocytosis Promotes Abdominal Aortic Aneurysm Formation

Circulating Matrix Metalloproteinases for Prediction of Aortic Dilatation in Children with Bicuspid Aortic Valve: A Single-Center, Observational Study

Circulating biomarkers have been proposed for early identification of aortic dilatation progression associated with bicuspid aortic valve (BAV), but matrix metalloproteinases (MMPs) are distinguished as signatures of increased extracellular matrix degradation, a landmark of aneurysm formation. The current study aims to identify the role of MMP-1, MMP-2, MMP-9, and the MMP inhibitor, TIMP-1, in identifying aortic dilation in children with BAV. We conducted a study on 73 children divided into two study groups, depending on the presence of aortic dilatation (group 1–43 BAV controls and group 2–30 children with BAV and aortic dilatation). Each patient underwent a cardiac ultrasound and, in each case, serum MMP-1, MMP-2, MMP-9, and TIMP-1 were quantified using xMAP technology. Comparison of the MMPs between the two study groups revealed significantly higher values only in the case of TIMP-1, among BAV controls. Moreover, the same TIMP-1 inversely correlated with aortic annulus absolute size and z score, as well as with ascending aorta z score. No particular correlation between the aortic phenotype and the presence of aortic dilatation was found. Future longitudinal research starting at pediatric ages could show the significance of MMPs screening in BAV individuals as predictors of aortic aneurysm formation.

Resolvin D2/GPR18 signaling enhances monocytic myeloid-derived suppressor cell function to mitigate abdominal aortic aneurysm formation.

Abdominal aortic aneurysm (AAA) formation is a chronic vascular pathology characterized by inflammation, leukocyte infiltration, and vascular remodeling. The aim of this study was to delineate the protective role of Resolvin D2 (RvD2), a bioactive isoform of specialized pro-resolving lipid mediators, via G-protein-coupled receptor 18 (GPR18) receptor signaling in attenuating AAAs. Importantly, RvD2 and GPR18 levels were significantly decreased in aortic tissue of AAA patients compared with controls. Furthermore, using an established murine model of AAA in C57BL/6 (WT) mice, we observed that treatment with RvD2 significantly attenuated aortic diameter, pro-inflammatory cytokine production, immune cell infiltration (neutrophils and macrophages), elastic fiber disruption, and increased smooth muscle cell α-actin expression as well as increased TGF-β2 and IL-10 expressions compared to untreated mice. Moreover, the RvD2-mediated protection from vascular remodeling and AAA formation was blocked when mice were previously treated with siRNA for GPR18 signifying the importance of RvD2/GPR18 signaling in vascular inflammation. Mechanistically, RvD2-mediated protection significantly enhanced infiltration and activation of monocytic myeloid-derived suppressor cells (M-MDSCs) by increasing TGF-β2 and IL-10 secretions in a GPR18-dependent manner to attenuate aortic inflammation and vascular remodeling. Collectively, this study demonstrates that RvD2 treatment induces an expansion of myeloid-lineage committed progenitors, such as M-MDSCs, activates GPR18-dependent signaling to enhance TGF-β2 and IL-10 secretion, and mitigates SMC activation that contributes to resolution of aortic inflammation and remodeling during AAA formation.

Olfactory receptor 2 signaling drives abdominal aortic aneurysm formation

Olfactory receptor 2 signaling drives abdominal aortic aneurysm formation

CD8+ T-cell deficiency protects mice from abdominal aortic aneurysm formation in response to calcium chloride2.

Abdominal aortic aneurysm (AAA) is an aneurysm-like dilated and highly fatal cardiovascular disease. CD8+ T cells have been shown to be critical for vascular pathological processes, but the contribution of these lymphocytes to vascular diseases remains elusive. Eight-week-old male wildtype (CD8+/+) and Cd8a knockout (CD8-/-) mice were used in a calcium chloride2 (CaCl2)-induced experimental AAA model. At 6 weeks after surgery, CD8+ T-cell deletion prevented the formation of AAA, accompanied by reductions of the levels of inflammatory (interferon-γ [IFN-γ], interleukin-1β, monocyte chemoattractant protein-1, intracellular adhesion molecule-1, vascular cell adhesion molecule-1, NOD-like receptor protein 3, caspase-1), oxidative stress [NADPH oxidase and gp91phox], and proteolysis (cathepsin S, cathepsin K, matrix metalloproteinase-2 [MMP-2] and MMP-9) proteins and/or genes in plasma and/or AAA tissues. Immunoreactivities of MMP-2 and MMP-9 were observed in macrophages. An injection of IFN-γ and adoptive transfer of CD8+ T cells of IFN-γ+/+ mice diminished CD8-/--mediated vasculoprotective actions in the AAA mice. In vitro, IFN-γ enhanced MMP-2 and MMP-9 gelatinolytic activities in macrophage and/or vascular smooth muscle cells. The vasculoprotective effects of CD8+ T-cell deletion in a mouse CaCl2-induced AAA model were likely attributable to, at least in part, the attenuation of IFN-γ-dependent inflammation action, oxidative stress production, and proteolysis, suggesting a novel therapeutic target for AAA formation by regulating CD8+ T-cell-derived IFN-γ secretion.

Complement C3a/C3aR inhibition alleviates the formation of aortic aneurysm in Marfan syndrome mice

Mutations in fibrillin 1 (FBN1) is the main cause of Marfan syndrome (MFS) with thoracic aortic aneurysm (TAA) as the main complication. Activation of the complement system plays a key role in the formation of thoracic and abdominal aortic aneurysms. However, the role of the complement system in MFS-associated aortic aneurysms remains unclear. In this study, we observed increased levels of complement C3a and C5a in the plasma of MFS patients and mouse, and the increased deposition of the activated complement system product C3b/iC3b was also observed in the elastic fiber rupture zone of 3-month-old MFS mice. The expression of C3a receptor (C3aR) was increased in MFS aortas, and recombinant C3a promoted the expression of cytokines in macrophages. The administration of a C3aR antagonist (C3aRA) attenuated the development of thoracic aortic aneurysms in MFS mice. The increased inflammation response and matrix metalloproteinases activities were also attenuated by C3aRA treatment in MFS mice. Therefore, these findings indicate that the complement C3a/C3aR inhibition alleviates the formation of aortic aneurysm in Marfan syndrome mice.

Effect of FluoRoquinolones on Aortic Growth, aortic stIffness and wave refLEctionS (FRAGILES study).

Background: The widespread use of fluoroquinolones has been associated with the formation, dissection, and rupture of aortic aneurysms. Arterial biomarkers are established predictors of cardiovascular events. The present study was designed to investigate the effect of quinolones on arterial stiffness and aortic size for the first time. Methods: We studied 28 subjects receiving short-term (<15 days) antibiotic therapy involving quinolones and 27 age- and sex-matched subjects receiving an alternative to quinolone antibiotics. The follow-up period was approximately 2 months. The study's primary endpoint was the carotid-femoral pulse wave velocity (cfPWV) difference between the two groups 2 months after therapy initiation. Secondary endpoints were the augmentation index corrected for heart rate (AIx@75) and sonographically assessed aortic diameters 2 months after the initial treatment. Results: Subjects had similar values of arterial biomarkers, blood pressure measurements, and aortic diameters at baseline. At follow-up, no significant change was observed between the two groups regarding the hemodynamic parameters and arterial biomarkers (p > 0.05 for all), i.e., cfPWV (7.9 ± 2.6 m/s for the control group vs. 8.1 ± 2.4 m/s for the fluoroquinolones group; p = 0.79), AIx@75 (22.6 ± 9.0% for the control group vs. 26.6 ± 8.1% for the fluoroquinolones group; p = 0.09), and aortic diameters. Conclusions: To our knowledge, FRAGILES is the first study to provide insights into the possible effects of fluoroquinolones on arterial biomarkers, showing that, at least in the short term, treatment with fluoroquinolones does not affect aortic function and diameter.