Progression Of Thoracic Aortic Aneurysms Research Articles

Age- and sex-specific biomechanics and extracellular matrix remodeling of the ascending aorta in a mouse model of severe Marfan syndrome.

Thoracic aortic aneurysm (TAA) is associated with Marfan syndrome (MFS), a connective tissue disorder caused by mutations in fibrillin-1. Sexual dimorphism has been recorded for TAA outcomes in MFS, but detailed studies on the differences in TAA progression in males and females and their relationships to outcomes have not been performed. The aims of this study were to determine sex differences in the diameter dilatation, mechanical properties, and extracellular matrix (ECM) remodeling over time in a severe mouse model (Fbn1mgR/mgR = MU) of MFS-associated TAA that has a shortened life span. Male and female MU and wildtype (WT) mice were used at 1-4 mo of age. Blood pressure and in vivo diameters of the ascending thoracic aorta were recorded using a tail-cuff system and ultrasound imaging, respectively. Ex vivo mechanics and ECM remodeling of the aorta were characterized using a biaxial test system and multiphoton imaging, respectively. We showed that mechanical properties, such as structural and material stiffness, and ECM remodeling, such as elastic and collagen fiber content, correlated with diameter dilatation during TAA progression. Male MU mice had accelerated rates of diameter dilatation, stiffening, and ECM remodeling compared with female MU mice which may have contributed to their decreased life span. The correlation of mechanical properties and ECM remodeling with diameter dilatation suggests that they may be useful biomarkers for TAA progression. The differences in diameter dilatation and life spans in male and female MU mice indicate that sex is an important consideration for managing thoracic aortic aneurysm in MFS. NEW & NOTEWORTHY Using a mouse model (Fbn1mgR/mgR = MU) of severe thoracic aortic aneurysm in Marfan syndrome (MFS), we found that male MU aorta had an accelerated time line and increased amounts of dilatation, stiffening, and extracellular matrix (ECM) remodeling compared with female MU aorta that may have contributed to an increased risk of fatigue failure with cyclic loading over time and a reduced life span. We suggest that aortic stiffness may provide useful information for clinical management of aneurysms in MFS.

TRIM25 activates Wnt/β-catenin signalling by destabilising MAT2A mRNA to drive thoracic aortic aneurysm development.

This study explored the roles of methionine adenosyltransferase 2A (MAT2A) and tripartite motif containing 25 (TRIM25) in the progression of thoracic aortic aneurysm (TAA). The TAA model was established based on the β-aminopropionitrile method. The effects of MAT2A on thoracic aortic lesions and molecular levels were analyzed by several pathological staining assays (hematoxylin-eosin, Verhoeff-Van Gieson, TUNEL) and molecular biology experiments (qRT-PCR, Western blot). Angiotensin II (Ang-II) was used to induce injury in vascular smooth muscle cells (VSMCs) in vitro. The effects of MAT2A, shMAT2A, shTRIM25 and/or Wnt inhibitor (IWR-1) on the viability, apoptosis and protein expressions of VSMCs were examined by CCK-8, Annexin V-FITC/PI and Western blot assays. In TAA mice, overexpression of MAT2A alleviated thoracic aortic injury, inhibited the aberrant expressions of aortic contractile proteins and dedifferentiation markers, and blocked the activation of Wnt/β-catenin pathway. In Ang-II-induced VSMCs, up-regulation of MAT2A increased cellular activity and repressed the expression of β-catenin protein. TRIM25 knockdown promoted activity of VSMCs, inhibited apoptosis, and blocked the Wnt/β-catenin pathway activation by binding to MAT2A. IWR-1 partially counteracted the regulatory effects of shMAT2A. Collectively, TRIM25 destabilises the mRNA of MAT2A to activate Wnt/β-catenin signaling and ultimately exacerbate TAA injury.

Exploiting the anti-fibrotic effects of statins on thoracic aortic aneurysm progression: results from a meta-analysis and experimental data.

Thoracic aortic aneurysm (TAA) that progress to acute aortic dissection is often fatal and there is no pharmacological treatment that can reduce TAA progression. We aim to evaluate statins' effects on TAA growth rate and outcomes using a meta-analysis approach. A detailed search related to the effects of statins on TAA was conducted according to PRISMA guidelines. The analyses of statins' effects on TAA growth rate were performed on 4 studies (n = 1850), while the impact on outcomes was evaluated on 3 studies (n = 2,867). Patients under statin treatment showed a reduced TAA growth rate (difference in means = -0.36cm/year; 95%CI: -0.64, -0.08; p = 0.013) when compared to controls, patients not taking statins. Regarding the outcomes (death, dissection, or rupture of the aorta, and the need for operative repair), statins exhibited a protective effect reducing the number of events (log odds ratio = -0.56; 95%CI: -1.06, -0.05; p = 0.030). In vitro, the anti-fibrotic effect of atorvastatin was tested on vascular smooth muscle cells (VMSC) isolated from patients with TAA. Our results highlighted that, in transforming growth factor beta 1 (TGF-β1) pro-fibrotic condition, VSMC expressed a significant lower amount of collagen type I alpha 1 chain (COL1A1) when treated with atorvastatin (untreated = +2.66 ± 0.23 fold-change vs. treated = +1.63 ± 0.09 fold-change; p = 0.014). Statins show a protective effect on TAA growth rate and adverse outcomes in patients with TAA, possibly via their anti-fibrotic properties on VSMC. Given the current lack of effective drug treatments for TAA, we believe our findings highlight the need for more in-depth research to explore the potential benefits of statins in this context.

Inhibition of alphaV integrins with cilengitide downregulates in vitro pro-fibrotic events in aortic smooth muscle cells and limits in vivo thoracic aortic aneurysm progression

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Italian Ministry of Health "Ricerca Finalizzata - Giovani Ricercatori" Background The ‘greatest artery’, i.e., the aorta, can be affected by either acute conditions or chronic disorders, such as the aneurysm, which is the segmental aortic dilation with at least 50% increase in the normal diameter. Aortic dilation can often lead to lethal events, such as aortic dissection and/or vessel rupture. The aneurysms occurring in the thoracic trait of the aorta (TAA) may depend on comorbidities, such as hypertension (i.e., sporadic non-syndromic TAA, sTAA), or on genetically determined conditions, such as Marfan syndrome (MFS). To date, the surgical replacement of aorta represents the most effective therapeutic approach in all TAA patients, since an etiologic pharmacological treatment is still lacking. Thus, the identification of novel disease targets is mandatory. Integrin receptors are key players in cellular mechanotransduction responses. Specifically, integrins containing αV subunit have been described as important mechanotransduction mediators and responsible for pro-fibrotic molecular events. Recently, it has been reported the effectiveness of a broad αV integrin inhibitor in limiting the TAA progression by acting on FAK/AKT/mTORC signaling pathway in a MFS in vivo model. However, the specific αV integrin subgroup directly involved in this detrimental process is yet not known. Purpose We evaluated the effectiveness of a specific αVβ3 and αVβ5 integrin inhibitor (i.e., cilengitide) in downregulating pro-fibrotic in vitro events on vascular smooth muscle cells (VSMC) isolated from TAA patients’ aortic wall, and in limiting in vivo thoracic aortic dilation on a MFS mice model. Results By comparison with healthy control (HC)-VSMC, both sTAA-VSMC and MFS-VSMC showed higher levels of αVβ3 and αVβ5 integrins as well as pro-fibrotic collagen I. The in vitro inhibition of these two αV integrins mediated by cilengitide resulted more effective in collagen I downregulation when compared with GLPG0187 (pan αV inhibitor). Noteworthy, the cilengitide-mediated αV integrin inhibition consistently tempered pro-fibrotic phenotype of sTAA- and MFS-VSMC by directly acting on both canonical (p-SMAD2/3) and non-canonical (p-ERK1/2) TGF-β downstream pathways and by downregulating mechanotransduction mediators (e.g., RhoA GTPase, ROCK1, talin-1). The 2D-echocardiographic results on MFS mice treated with cilengitide confirmed the greater effectiveness of this drug in limiting the TAA progression, in comparison not only with vehicle but also with the broad integrin inhibitor GLPG0187. Conclusion Altogether, our results improve the know-how on αV integrin inhibition, highlighting the role of cilengitide as potential target for future therapeutic approaches to limit TAA progression, both in sporadic and in MFS patients.

Analysis of Vascular Smooth Muscle Cells from Thoracic Aortic Aneurysms Reveals DNA Damage and Cell Cycle Arrest as Hallmarks in Bicuspid Aortic Valve Patients.

Thoracic aortic aneurysm (TAA) is mainly sporadic and with higher incidence in the presence of a bicuspid aortic valve (BAV) for unknown reasons. The lack of drug therapy to delay TAA progression lies in the limited knowledge of pathophysiology. We aimed to identify the molecular hallmarks that differentiate the aortic dilatation associated with BAV and tricuspid aortic valve (TAV). Aortic vascular smooth muscle cells (VSMCs) isolated from sporadic TAA patients with BAV or TAV were analyzed by mass spectrometry. DNA oxidative damage assay and cell cycle profiling were performed in three independent cohorts supporting proteomics data. The alteration of secreted proteins was confirmed in plasma. Stress phenotype, oxidative stress, and enhanced DNA damage response (increased S-phase arrest and apoptosis) were found in BAV-TAA patients. The increased levels of plasma C1QTNF5, LAMA2, THSB3, and FAP confirm the enhanced stress in BAV-TAA. Plasma FAP and BGN point to an increased inflammatory condition in TAV. The arterial wall of BAV patients shows a limited capacity to counteract drivers of sporadic TAA. The molecular pathways identified support the need of differential molecular diagnosis and therapeutic approaches for BAV and TAV patients, showing specific markers in plasma which may serve to monitor therapy efficacy.

Murine double minute 2-mediated estrogen receptor 1 degradation activates macrophage migration inhibitory factor to promote vascular smooth muscle cell dedifferentiation and oxidative stress during thoracic aortic aneurysm progression

Estrogen receptor 1 (ESR1) has been recently demonstrated as a potential diagnostic biomarker for thoracic aortic aneurysm (TAA). However, its precise role in the progression of TAA remains unclear. In this study, TAA models were established in ApoE-knockout mice and primary mouse vascular smooth muscle cells (VSMCs) through treatment with angiotensin (Ang) II. Our findings revealed a downregulation of ESR1 in Ang II-induced TAA mice and VSMCs. Upregulation of ESR1 mitigated expansion and cell apoptosis in the mouse aorta, reduced pathogenetic transformation of VSMCs, and reduced inflammatory infiltration and oxidative stress both in vitro and in vivo. Furthermore, we identified macrophage migration inhibitory factor (MIF) as a biological target of ESR1. ESR1 bound to the MIF promoter to suppress its transcription. Artificial MIF restoration negated the mitigating effects of ESR1 on TAA. Additionally, we discovered that murine double minute 2 (MDM2) was highly expressed in TAA models and mediated protein degradation of ESR1 through ubiquitination modification. Silencing of MDM2 reduced VSMC dedifferentiation and suppressed oxidative stress. However, these effects were reversed upon further silencing of ESR1. In conclusion, this study demonstrates that MDM2 activates MIF by mediating ESR1 degradation, thus promoting VSMC dedifferentiation and oxidative stress during TAA progression.

Silencing COQ8B in Aortic Smooth Muscle Cells Reveals Cellular Dysfunction Related to Changes in Cell Proliferation

Background/Objective: Thoracic aortic aneurysm (TAA) is a prevalent disorder that predisposes to aortic dissection. Prior work identified the ubiquinone biosynthesis gene COQ8B as a genetic modifier of TAA progression. We sought to determine the impact of decreased COQ8B on global transcription in aortic smooth muscle cells (SMCs).
 Methods: Primary human aortic SMCs from a healthy donor were seeded in 12-well plates. Six experimental conditions were created, each with 3 replicates: 1) siRNA targeting COQ8B (siCOQ8B); 2) siRNA targeting the dominant TAA gene SMAD3 (siSMAD3); 3) negative controlsiRNA (siNeg); 4) siCOQ8B and siSMAD3; 5) siCOQ8B with Angiotensin II (AngII) stimulation (siCOQ8B+AngII); 6) siNeg+AngII. RNA was extracted approximately 48 hours post-siRNA transfection and, for AngII conditions, after 1 hour of incubation with AngII (100 nM). mRNAsequencing was performed and downstream analysis utilized R packages EdgeR and topGO.
 Results: Multidimensional scaling identified distinct clustering of samples by experimental condition. Downregulated genes in siCOQ8B were enriched for Gene Ontology pathways related to cell proliferation including cell cycle regulators, DNA replication, and mitosis. MYOCD, a master regulator of SMC homeostasis, was downregulated. Similar proliferation-related pathways were enriched in siCOQ8B+siSMAD3 and siCOQ8B+AngII compared to siNeg. Pathways related to cell proliferation in siCOQ8B+AngII cells were downregulated when compared to siCOQ8B which indicates that AngII infusion in the context of COQ8B silencing may further dysregulate cell proliferation pathways.
 Conclusion: The results indicate that COQ8B has an important role in cell cycle processes in aortic SMCs, including when SMCs are exposed to stressors associated with TAA development. Stimulation of angiotensin receptors may exacerbate the effects of decreased COQ8B in these processes. To investigate these experimental results in human pathology, bulk RNA samples and intact nuclei have been isolated from frozen human aortic specimens and prepared for transcriptomic analysis.

Effects of COL1A1 and SYTL2 on inflammatory cell infiltration and poor extracellular matrix remodeling of the vascular wall in thoracic aortic aneurysm.

Thoracic aortic aneurysm (TAA) is a fatal cardiovascular disease, the pathogenesis of which has not yet been clarified. This study aimed to identify and validate the diagnostic markers of TAA to provide a strong theoretical basis for developing new methods to prevent and treat this disease. Gene expression profiles of the GSE9106, GSE26155, and GSE155468 datasets were acquired from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were identified using the "limma" package in R. Least absolute shrinkage and selection operator (LASSO), support vector machine-recursive feature elimination (SVM-RFE), random forest, and binary logistic regression analyses were used to screen the diagnostic marker genes. Single-sample gene set enrichment analysis (ssGSEA) was used to estimate immune cell infiltration in TAA. A total of 16 DEGs were identified. The enrichment and functional correlation analyses showed that DEGs were mainly associated with inflammatory response pathways and collagen-related diseases. Collagen type I alpha 1 chain ( COL1A1 ) and synaptotagmin like 2 ( SYTL2 ) were identified as diagnostic marker genes with a high diagnostic value for TAA. The expression of COL1A1 and SYTL2 was considerably higher in TAA vascular wall tissues than in the corresponding normal tissues, and there were significant differences in the infiltration of immune cells between TAA and normal vascular wall tissues. Additionally, COL1A1 and SYTL2 expression were associated with the infiltration of immune cells in the vascular wall tissue. Single-cell analysis showed that COL1A1 in TAA was mainly derived from fibroblasts and SYTL2 mainly from cluster of differentiation (CD)8 + T cells. In addition, single-cell analysis indicated that fibroblasts and CD8 + T cells in TAA were significantly higher than those in normal arterial wall tissue. COL1A1 and SYTL2 may serve as diagnostic marker genes for TAA. The upregulation of SYTL2 and COL1A1 may be involved in the inflammatory infiltration of the vessel wall and poor extracellular matrix remodeling, promoting the progression of TAA.

Changes in transmural mass transport correlate with ascending thoracic aortic aneurysm diameter in a fibulin-4 E57K knockin mouse model.

Thoracic aortic aneurysm is characterized by dilation of the aortic diameter by greater than 50%, which can lead to dissection or rupture. Common histopathology includes extracellular matrix remodeling that may affect transmural mass transport, defined as the movement of fluids and solutes across the wall. We measured in vitro ascending thoracic aorta mass transport in a mouse model with partial aneurysm phenotype penetration due to a mutation in the extracellular matrix protein fibulin-4 [Fbln4E57K/E57K, referred to as MU-A (aneurysm) or MU-NA (no aneurysm)]. To push the aneurysm phenotype, we also included MU mice with reduced levels of lysyl oxidase [Fbln4E57K/E57K;Lox+/-, referred to as MU-XA (extreme aneurysm)] and compared all groups to wild-type (WT) littermates. The phenotype variation allows investigation of how aneurysm severity correlates with mass transport parameters and extracellular matrix organization. We found that MU-NA ascending thoracic aortae have similar hydraulic conductance (Lp) to WT, but 397% higher solute permeability (ω) for 4 kDa FITC-dextran. In contrast, MU-A and MU-XA ascending thoracic aortae have 44-68% lower Lp and similar ω to WT. The results suggest that ascending thoracic aortic aneurysm progression involves an initial increase in ω, followed by a decrease in Lp after the aneurysm has formed. All MU ascending thoracic aortae are longer and have increased elastic fiber fragmentation in the extracellular matrix. There is a negative correlation between diameter and Lp or ω in MU ascending thoracic aortae. Changes in mass transport due to elastic fiber fragmentation could contribute to aneurysm progression or be leveraged for treatment.NEW & NOTEWORTHY Transmural mass transport is quantified in the ascending thoracic aorta of mice with a mutation in fibulin-4 that is associated with thoracic aortic aneurysms. Fluid and solute transport depend on aneurysm severity, correlate with elastic fiber fragmentation, and may be affected by proteoglycan deposition. Transport properties of the ascending thoracic aorta are provided and can be used in computational models. The changes in mass transport may contribute to aneurysm progression or be leveraged for aneurysm treatment.

Dysfunctions of the C-type natriuretic peptide signaling pathway involved in the development of thoracic aortic aneurysm in Marfan patients

Marfan Syndrome (MFS) is an autosomal dominant inherited connective tissue disorder affecting the cardio-vascular system. Development of thoracic aortic aneurysms (TAA) leading to dissections and ruptures is the primary cause of morbidity and mortality in these patients. No treatment really cures Marfan patients. Interestingly, in humans, mutations in the gene coding for the C-type natriuretic peptide (CNP) or its receptors lead to a “Marfan-like syndrome”. CNP is a local regulator of skeletal growth and of vascular homeostasis, remodeling and angiogenesis. CNP binds to NPR-B or NPR-C receptors, both expressed on endothelial and vascular smooth muscle cells (vSMCs) and modulates the intracellular cGMP and cAMP levels. The aim of this project is to determine whether altered CNP signaling pathway contributes to TAA development and progression to rupture in Marfan patients. Plasma and aorta biopsies were taken from Marfan patients and from Fbn1C1039G/+ mice. The CNP, TGF-beta, cAMP and cGMP concentrations were measured in the plasma. mRNA and protein levels evaluated by qRT-PCR, and Western blot analysis in aortic tissue. Male and female mice studied and alterations of the aorta structure analyzed by ultrasound imaging. Plasma proCNP level in Marfan patients depends on the age and the TAA development. Increased levels found in young patients presenting no or reduced TAA and decreased levels in patients with TAA compared to age and sex-matched non-Marfan patients. CNP and NPR-C decreased at the mRNA and protein levels in the aorta of Marfan patients when compared to the same aorta in non-Marfan patients. In Fbn1+/- mice, aortic structure alterations are detected from 10 weeks in males and 34 weeks in females. CNP and NPR-C mRNA and protein levels drastically decreased in the thoracic aorta in 2–7 week-old male mice and in 34 week-old female mice. In 52-week old Fbn1+/- mice, the plasma cAMP level is increased in males and not in females, whereas the plasma cGMP protein level is increased in females but not in males. CNP injections in 3-week old Fbn1+/- male mice partially prevented the aorta structure alterations. A deficit in CNP protein level or in the expression of the NPR-C receptor contributes to the development and progression of TAA.

Effects of PTSD-Dependent Neurogenic Hypertension and Inflammation on Thoracic Aortic Wall Homeostasis

Objective: Post-traumatic stress disorder (PTSD) in patients is associated with hypertension, increased heart rate, and elevated plasma proinflammatory cytokines, which also are risk factors for the development of cardiovascular conditions, such as thoracic aortic aneurysm (TAA). Although the association between stress and aortic pathology has been suggested, the exact mechanism linking the two is unknown. Our hypothesis is that PTSD-induced changes in mechanical and inflammatory signaling alter thoracic aortic wall homeostasis, which can predispose to aortic disease. Methods: Adult male and female C57BL/6 mice (n=7) underwent PTSD induction consisting of inescapable foot shock (five x 1 sec, 1 mA foot shocks over 6 min paired with a 20 sec 80 db tone (conditioned stimulus)) followed by single prolonged stress events. Mice were subjected to behavioral testing at 4-week intervals over a 16-week paradigm to determine their PTSD-like phenotype. The behavioral tests were chosen to assess for each of the human criteria of PTSD based on the DSM-5. A composite t-score was generated for each mouse derived from their mean individual z-score for each parameter, of each behavioral test. Mice with a composite t-score above 1.96 were considered to have a PTSD-like phenotype. Blood pressure was measured (CODA, tail-cuff) at baseline and at 4-week intervals. At terminal study, thoracic aortic diameter was measured by digital microscopy. Plasma was collected to measure circulating cytokines and aortic tissue was harvested for biochemistry and histology. Aortic structure was examined for changes in elastic lamellae, collagen deposition, and cellular content. Control mice (n=8) underwent the same procedures except for PTSD induction. Results: Our protocol generated a PTSD-like phenotype in 71% (5 of 7) of the mice. PTSD mice had significantly higher systolic blood pressures following a conditioned stimulus (PTSD (n=5), 153 ± 8mmHg; control (n=8), 129 ± 7mmHg, p<0.05). PTSD mice also had increased plasma proinflammatory cytokines (IL1-α, IL-3, IL-5, IL-7, IL-9, all p<0.05), enhanced extracellular matrix remodeling (ECM), and larger aortic diameters than control mice (PTSD (n=5), 712.9 ± 97.6μm; control (n=8), 584.2 ± 102.7μm, p <0.05). Conclusion: Our PTSD-like mouse model recapitulated the human phenotype showing elevated systolic blood pressure and increased circulating proinflammatory cytokines. Increase thoracic aortic diameter and changes in the ECM suggest that PTSD can alter structural homeostasis in the aortic wall, predisposing the thoracic aorta to development of further pathology. Future studies will examine PTSD effects on TAA progression in a mouse model. NIH-NCATS TL1 TR00145-08 & UL1TR001450-08 (HH) and VA Merit Award I01-BX000904-08A1 (JAJ) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Influence of aortic aneurysm on the local distribution of NO and O2 using image-based computational fluid dynamics

There is a pressing need to establish novel biomarkers to predict the progression of thoracic aortic aneurysm (TAA) dilatation. Aside from hemodynamics, the roles of oxygen (O2) and nitric oxide (NO) in TAA pathogenesis are potentially significant. As such, it is imperative to comprehend the relationship between aneurysm presence and species distribution in both the lumen and aortic wall. Given the limitations of existing imaging methods, we propose the use of patient-specific computational fluid dynamics (CFD) to explore this relationship. We have performed CFD simulations of O2 and NO mass transfer in the lumen and aortic wall for two cases: a healthy control (HC) and a patient with TAA, both acquired using 4D-flow magnetic resonance imaging (MRI). The mass transfer of O2 was based on active transport by hemoglobin, while the local variations of the wall shear stress (WSS) drove NO production. Comparing hemodynamic properties, the time-averaged WSS was considerably lower for TAA, while the oscillatory shear index and endothelial cell activation potential were notably elevated. O2 and NO showed a non-uniform distribution within the lumen and an inverse correlation between the two species. We identified several locations of hypoxic regions for both cases due to lumen-side mass transfer limitations. In the wall, NO varied spatially, with a clear distinction between TAA and HC. In conclusion, the hemodynamics and mass transfer of NO in the aorta exhibit the potential to serve as a diagnostic biomarker for TAA. Furthermore, hypoxia may provide additional insights into the onset of other aortic pathologies.

Circ_0000595 knockdown alleviates CoCl2-mediated effects in VSMCs by regulating the miR-582-3p/ADAM10 axis.

Thoracic aortic aneurysm (TAA) is a serious vascular disease causing the death of elder people. Accumulating studies have reported that circular RNAs (circRNAs) are implicated in the regulation of aortic aneurysms. However, the role of circ_0000595 in the progression of TAA is still unclear. Quantitative real-time PCR (qRT-PCR) and western blotting were implemented to assess circ_0000595, microRNA (miR)-582-3p, guanine nucleotide-binding protein alpha subunit (ADAM10), PCNA, Bax, and Bcl-2 expression. The proliferation of vascular smooth muscle cells was determined using cell counting kit 8 (CCK-8) and 5-ethynyl-2-deoxyuridine (EdU). Cell apoptosis was measured using flow cytometry, and caspase-3 activity was analyzed using a commercial kit. After bioinformatics analysis, the interaction between miR-582-3p and circ_0000595 or ADAM10 was validated using a dual-luciferase reporter and RNA immunoprecipitation. As compared with controls, TAA tissues and CoCl2-induced VSMCs displayed high expression of circ_0000595 and ADAM10, and low expression of miR-582-3p. CoCl2 treatment evidently suppressed VSMC proliferation and promoted VSMCs apoptosis, and these impacts were reverted by circ_0000595 knockdown. Circ_0000595 acted as a molecular sponge for miR-582-3p, and circ_0000595 silencing-mediated influences in CoCl2-induced VSMCs were overturned by miR-582-3p inhibitor. ADAM10 was confirmed as a target gene of miR-582-3p, and miR-582-3p overexpression-induced influence was almost restored by overexpressed ADAM10 in CoCl2-induced VSMCs. Besides, circ_0000595 contributed to ADAM10 protein expression by sponging miR-582-3p. Our data verified that circ_0000595 silencing might attenuate CoCl2-mediated impacts in VSMCs by regulating the miR-582-3p/ADAM10 axis, providing new potential roads for treating TAA.

Ciprofloxacin exacerbates dysfunction of smooth muscle cells in a microphysiological model of thoracic aortic aneurysm.

Ciprofloxacin use may be associated with adverse aortic events. However, the mechanism underlying the effect of ciprofloxacin on the progression of thoracic aortic aneurysm (TAA) is not well understood. Using an in vitro microphysiological model, we treated human aortic smooth muscle cells (HASMCs) derived from patients with bicuspid aortic valve (BAV)- or tricuspid aortic valve (TAV)-associated TAAs with ciprofloxacin. TAA C57/BL6 mouse models were utilized to verify the effects of ciprofloxacin exposure. In the microphysiological model, real-time polymerase chain reaction, western blotting, and RNA sequencing showed that ciprofloxacin exposure was associated with a downregulated contractile phenotype, an upregulated inflammatory reaction, and extracellular matrix (ECM) degradation in the normal HASMCs derived from the non-diseased aorta. Ciprofloxacin induced mitochondrial dysfunction in the HASMCs and further increased apoptosis by activating the ERK1/2 and P38 mitogen-activated protein kinase pathways. These adverse effects appeared to be more severe in the HASMCs derived from BAV- and TAV-associated TAAs than in the normal HASMCs when the ciprofloxacin concentration exceeded 100 µg/mL. In the aortic walls of the TAA-induced mice, ECM degradation and apoptosis were aggravated after ciprofloxacin exposure. Therefore, ciprofloxacin should be used with caution in patients with BAV- or TAV-associated TAAs.

Transcriptomics Provides Novel Insights into the Regulatory Mechanism of IncRNA HIF1 A-AS1 on Vascular Smooth Muscle Cells.

Thoracic aortic aneurysm is a potentially fatal disease with a strong genetic contribution. The dysfunction of vascular smooth muscle cells (VSMCs) contributes to the formation of this aneurysm. Although previous studies suggested that long non-coding ribonucleic acid (RNA) hypoxia inducible factor 1 α-antisense RNA 1 (HIF1A-AS1) exerted a vital role in the progression and pathogenesis of thoracic aortic aneurysm, we managed to find a new regulatory mechanism of HIF1A-AS1 in VSMCs via transcriptomics. Cell viability was detected by the cell counting kit-8 assay. Cell apoptosis was assessed by Annexin V-fluorescein isothiocyanate/propidium iodide double staining. Transwell migration assay and wound healing assay were performed to check the migration ability of HIF1A-AS1 on VSMCs. The NextSeq XTen system (Illumina) was used to collect RNA sequencing data. Lastly, reverse transcription-quantitative polymerase chain reaction confirmed the veracity and reliability of RNA-sequencing results. We observed that overexpressing HIF1A-AS1 successfully promoted apoptosis, significantly altered cell cycle distribution, and greatly attenuated migration in VSMCs, further highlighting the robust promoting effects of HIF1A-AS1 to thoracic aortic aneurysm. Moreover, transcriptomics was implemented to uncover its underlying mechanism. A total of 175 differently expressed genes were identified, with some of them enriched in apoptosis, migration, and cell cycle-related pathways. Intriguingly, some differently expressed genes were noted in vascular development or coagulation function pathways. We suggest that HIF1A-AS1 mediated the progression of thoracic aortic aneurysm by not only regulating the function of VSMCs, but also altering vascular development or coagulation function.

Analysis and Interpretation of Pathophysiologic Mechanisms Associated With the Development and Progression of Thoracic Aortic Aneurysms Through Molecular Imaging in Murine Models

Analysis and Interpretation of Pathophysiologic Mechanisms Associated With the Development and Progression of Thoracic Aortic Aneurysms Through Molecular Imaging in Murine Models

Protective Role of Endothelial Fibulin-4 in Valvulo-Arterial Integrity.

Background Homeostasis of the vessel wall is cooperatively maintained by endothelial cells (ECs), smooth muscle cells, and adventitial fibroblasts. The genetic deletion of fibulin-4 (Fbln4) in smooth muscle cells (SMKO) leads to the formation of thoracic aortic aneurysms with the disruption of elastic fibers. Although Fbln4 is expressed in the entire vessel wall, its function in ECs and relevance to the maintenance of valvulo-arterial integrity are not fully understood. Methods and Results Gene silencing of FBLN4 was conducted on human aortic ECs to evaluate morphological changes and gene expression profile. Fbln4 double knockout (DKO) mice in ECs and smooth muscle cells were generated and subjected to histological analysis, echocardiography, Western blotting, RNA sequencing, and immunostaining. An evaluation of the thoracic aortic aneurysm phenotype and screening of altered signaling pathways were performed. Knockdown of FBLN4 in human aortic ECs induced mesenchymal cell-like changes with the upregulation of mesenchymal genes, including TAGLN and MYL9. DKO mice showed the exacerbation of thoracic aortic aneurysms when compared with those of SMKO and upregulated Thbs1, a mechanical stress-responsive molecule, throughout the aorta. DKO mice also showed progressive aortic valve thickening with collagen deposition from postnatal day 14, as well as turbulent flow in the ascending aorta. Furthermore, RNA sequencing and immunostaining of the aortic valve revealed the upregulation of genes involved in endothelial-to-mesenchymal transition, inflammatory response, and tissue fibrosis in DKO valves and the presence of activated valve interstitial cells. Conclusions The current study uncovers the pivotal role of endothelial fibulin-4 in the maintenance of valvulo-arterial integrity, which influences thoracic aortic aneurysm progression.

Attenuation of Smooth Muscle Cell Phenotypic Switching by Angiotensin 1-7 Protects against Thoracic Aortic Aneurysm.

Thoracic aortic aneurysm (TAA) involves extracellular matrix (ECM) remodeling of the aortic wall, leading to reduced biomechanical support with risk of aortic dissection and rupture. Activation of the renin-angiotensin system, and resultant angiotensin (Ang) II synthesis, is critically involved in the onset and progression of TAA. The current study investigated the effects of angiotensin (Ang) 1-7 on a murine model of TAA. Male 8-10-week-old ApoEKO mice were infused with Ang II (1.44 mg/kg/day) and treated with Ang 1-7 (0.576 mg/kg/day). ApoEKO mice developed advanced TAA in response to four weeks of Ang II infusion. Echocardiographic and histological analyses demonstrated increased aortic dilatation, excessive structural remodelling, perivascular fibrosis, and inflammation in the thoracic aorta. Ang 1-7 infusion led to attenuation of pathological phenotypic alterations associated with Ang II-induced TAA. Smooth muscle cells (SMCs) isolated from adult murine thoracic aorta exhibited excessive mitochondrial fission, oxidative stress, and hyperproliferation in response to Ang II. Treatment with Ang 1-7 resulted in inhibition of mitochondrial fragmentation, ROS generation, and hyperproliferation. Gene expression profiling used for characterization of the contractile and synthetic phenotypes of thoracic aortic SMCs revealed preservation of the contractile phenotype with Ang 1-7 treatment. In conclusion, Ang 1-7 prevented Ang II-induced vascular remodeling and the development of TAA. Enhancing Ang 1-7 actions may provide a novel therapeutic strategy to prevent or delay the progression of TAA.

ANGIOTENSIN 1-7 EXERTS PROTECTIVE EFFECTS IN THORACIC AORTIC ANEURYSM BY ATTENUATING SMOOTH MUSCLE CELL PHENOTYPIC SWITCHING

ANGIOTENSIN 1-7 EXERTS PROTECTIVE EFFECTS IN THORACIC AORTIC ANEURYSM BY ATTENUATING SMOOTH MUSCLE CELL PHENOTYPIC SWITCHING

Neural operator learning of heterogeneous mechanobiological insults contributing to aortic aneurysms.

Thoracic aortic aneurysm (TAA) is a localized dilatation of the aorta that can lead to life-threatening dissection or rupture. In vivo assessments of TAA progression are largely limited to measurements of aneurysm size and growth rate. There is promise, however, that computational modelling of the evolving biomechanics of the aorta could predict future geometry and properties from initiating mechanobiological insults. We present an integrated framework to train a deep operator network (DeepONet)-based surrogate model to identify TAA contributing factors using synthetic finite-element-based datasets. For training, we employ a constrained mixture model of aortic growth and remodelling to generate maps of local aortic dilatation and distensibility for multiple TAA risk factors. We evaluate the performance of the surrogate model for insult distributions varying from fusiform (analytically defined) to complex (randomly generated). We propose two frameworks, one trained on sparse information and one on full-field greyscale images, to gain insight into a preferred neural operator-based approach. We show that this continuous learning approach can predict the patient-specific insult profile associated with any given dilatation and distensibility map with high accuracy, particularly when based on full-field images. Our findings demonstrate the feasibility of applying DeepONet to support transfer learning of patient-specific inputs to predict TAA progression.