Thoracic Aortic Aneurysm Formation Research Articles

Bioengineered vascular grafts with a pathogenic TGFBR1 variant model aneurysm formation in vivo and reveal underlying collagen defects.

Thoracic aortic aneurysm (TAA) is a life-threatening vascular disease frequently associated with underlying genetic causes. An inadequate understanding of human TAA pathogenesis highlights the need for better disease models. Here, we established a functional human TAA model in an animal host by combining human induced pluripotent stem cells (hiPSCs), bioengineered vascular grafts (BVGs), and gene editing. We generated BVGs from isogenic control hiPSC-derived vascular smooth muscle cells (SMCs) and mutant SMCs gene-edited to carry a Loeys-Dietz syndrome (LDS)-associated pathogenic variant (TGFBR1A230T). We also generated hiPSC-derived BVGs using cells from a patient with LDS (PatientA230T/+) and using genetically corrected cells (Patient+/+). Control and experimental BVGs were then implanted into the common carotid arteries of nude rats. The TGFBR1A230T variant led to impaired mechanical properties of BVGs, resulting in lower burst pressure and suture retention strength. BVGs carrying the variant dilated over time in vivo, resembling human TAA formation. Spatial transcriptomics profiling revealed defective expression of extracellular matrix (ECM) formation genes in PatientA230T/+ BVGs compared with Patient+/+ BVGs. Histological analysis and protein assays validated quantitative and qualitative ECM defects in PatientA230T/+ BVGs and patient tissue, including decreased collagen hydroxylation. SMC organization was also impaired in PatientA230T/+ BVGs as confirmed by vascular contraction testing. Silencing of collagen-modifying enzymes with small interfering RNAs reduced collagen proline hydroxylation in SMC-derived tissue constructs. These studies demonstrated the utility of BVGs to model human TAA formation in an animal host and highlighted the role of reduced collagen modifying enzyme activity in human TAA formation.

Integrative multi-omics analyses reveal vesicle transport as a potential target for thoracic aortic aneurysm

BackgroundThoracic aortic aneurysm (TAA) refers to dilation and enlargement of the thoracic aorta caused by various reasons. Most patients have no apparent symptoms in the early stage and are subject to a poor prognosis once the aneurysm ruptures. It is crucial to identify individuals who are predisposed to TAA and to discover effective therapeutic targets for early intervention. MethodsWe conducted a label-free quantitative proteomic analysis among aorta tissue samples from TAA patients to screen differentially expressed proteins (DEPs) and key co-expression modules. Two datasets from Gene Expression Omnibus (GEO) database were included for integrative analysis, and the identified genes were subjected to immunohistochemistry (IHC) validation. Detailed vesicle transport related enrichment analysis was conducted and two FDA-approved drugs, chlorpromazine (CPZ) and chloroquine (CQ), were selected for in vivo inhibition of vesicle transport in mice TAA model. The diameter of thoracic aorta, mortality and histological differences after interventions were evaluated. ResultsWe found significant enrichments in functions involved with vesicle transport, extracellular matrix organizing, and infection diseases in TAA. Endocytosis was the most essential vesicle transport process in TAA formation. Interventions with CPZ and CQ significantly reduced the aneurysm diameter and elastin degradation in vivo and enhanced the survival rates of TAA mice. ConclusionsWe systematically screened the aberrantly regulated bioprocesses in TAA based on integrative multi-omics analyses, identified and demonstrated the importance of vesicle transport in the TAA formation. Our study provided pilot evidence that vesicular transport was a potential and promising target for the treatment of TAA.

From Natural History to Contemporary Management of Aortic Diseases: A State-of-the-Art Review of Thoracic Aortic Aneurysm

Thoracic aortic aneurysms (TAAs) are commonly seen in cardiovascular practice. Acquired and genetic conditions contribute to TAA formation. The natural history of genetically mediated TAA underscores the importance of early detection, regular monitoring, and prompt treatment to prevent complications, including dissection or rupture. The prognosis is poor in the event of acute dissection, with high rates of in-hospital mortality. Healthcare providers need to remain vigilant in their efforts to identify and surveil TAA to reduce the risk of complications. In this manuscript, we review the natural history of TAA, discuss the most common causes leading to the development of TAA, assess the value and limitations of diagnostic modalities, and review the management and long-term surveillance of patients with aortic disease.

Balloon-expandable cheatham-platinum stents versus self-expandable nitinol stents in coarctation of aorta: 3-year outcome of a randomized clinical trial

Abstract Introduction Although stenting showed early promising results in the treatment of patients with coarctation of aorta (CoA), its long-term benefit it is scarcely studied. Previously, we have shown, balloon-expandable stents (BES) and self-expandable (SES) stents were both effective and safe during 12-month follow up in the treatment of native CoA. Purpose To report the 3-year outcomes of BES versus SES stents in patients with native CoA. Methods Adult patients with de novo native CoA were randomized into Cheatham-platinum BES and uncovered nitinol SES groups in this parallel-group, open-label, blinded endpoint randomized clinical trial. All randomized patients were assigned to the 3-year structural follow up, consisted of clinical examination (including blood pressure measurement), exercise test for detecting masked hypertension, aortic CT angiography and transthoracic echocardiography. The 3-year incidence of recoarctation of aorta, thoracic aortic aneurysm formation, and residual hypertension were reported as the main long-term outcomes. Results Of the 92 patients initially randomized, 71 patients were participated in 3-year structural follow-up (Figure 1). Residual hypertension, defined as a persistent need for antihypertensive drugs at 3-year were significantly higher in BES (25 (71.4%) versus 17 (47.2%) patients (risk ratio (RR), 1.51, 95% confidence interval (CI), [1.00 to 2.26], p= 0.03) (Figure 2). Apart from five patients diagnosed with recoarctation during the first year of follow-up, no new cases of recoarctation were detected between 1 to 3-year follow up. Of note 2 of 3 patients with recorctation in the BES group, needed a second reintervention during the long-term follow up. Thoracic aortic aneurysm formation was not different in both stent types (4 (11.4%) versus 2 (5.6%) patients (RR, 2.06, 95% CI, [0.40 to 10.52], p= 0.37). Three-year median differences of ascending aorta and aortic arch were not different between the two groups. Conclusion Overall, both BES and SES were safe and effective in the long-term follow up. The rate of recoarctation was low even in the long-term follow up, which were safely reintervene. A hypothesis-generating difference were detected between two types of stents on residual hypertension which needs to be verified in larger studies.Baseline Characteristics and Study Flow3-year Outcomes

Abstract P3151: A Unique Profile Of Extracellular Vesicles In Marfan Patients With Thoracic Aortic Aneurysm

Objectives: Extracellular vesicles (EVs) [exosomes and microvesicles] have significant diagnostic and therapeutic potential, but clinical application is limited by disparate methods of data collection. Exosomes are 30-100nm, and microvesicles are 100-300nm lipid bilayer vesicles that originate from all cell types. Marfan Syndrome (MFS) is a connective tissue disorder. Thoracic aortic aneurysm (TAA) formation and dissection are the leading causes of death in MFS patients. Early identification of TAAs in MFS patients is imperative and will mitigate morbidity and mortality. This study’s goal was to develop a reproducible workflow for isolation and quantification of EVs 30-300nm and test the hypothesis that number and size distribution are altered in MFS patients with TAA. Methods: A method of standardized reproducible measurement of EVs isolated from plasma was developed. This includes isolation by automated size exclusion chromatography and quantification of size distribution by tunable resistive pulse sensing. Characteristic markers specific to both EV subtypes were confirmed by immunoblot. Results: EVs isolated from control plasma (n=12) and Marfan TAA plasma (n=6) were measured for concentration (control 0.60 x 10 11 particles/mL, MFS TAA 1.47 x 10 11 particles/mL), mean diameter (control 77.75nm, MFS TAA 69.92nm), mode diameter (control 65.50nm, MFS TAA 60.50nm), and d90/d10 ratio (control 1.68, MFS TAA 271 1.57). Conclusion: MFS patients with TAA have more EVs with a smaller diameter, suggesting increased export and a shift in ratio of microvesicles:exosomes. This may be used as a diagnostic tool or potential therapeutic target. This scalable protocol ensures recovery of intact EVs suitable for downstream biochemical and functional analyses. Simultaneous measurement quantifies EV concentration and size distribution absolutely, correcting for variations, providing a novel method of standardization.

SIRT6 is an epigenetic repressor of thoracic aortic aneurysms via inhibiting inflammation and senescence

Thoracic aortic aneurysms (TAAs) develop asymptomatically and are characterized by dilatation of the aorta. This is considered a life-threating vascular disease due to the risk of aortic rupture and without effective treatments. The current understanding of the pathogenesis of TAA is still limited, especially for sporadic TAAs without known genetic mutation. Sirtuin 6 (SIRT6) expression was significantly decreased in the tunica media of sporadic human TAA tissues. Genetic knockout of Sirt6 in mouse vascular smooth muscle cells accelerated TAA formation and rupture, reduced survival, and increased vascular inflammation and senescence after angiotensin II infusion. Transcriptome analysis identified interleukin (IL)-1β as a pivotal target of SIRT6, and increased IL-1β levels correlated with vascular inflammation and senescence in human and mouse TAA samples. Chromatin immunoprecipitation revealed that SIRT6 bound to the Il1b promoter to repress expression partly by reducing the H3K9 and H3K56 acetylation. Genetic knockout of Il1b or pharmacological inhibition of IL-1β signaling with the receptor antagonist anakinra rescued Sirt6 deficiency mediated aggravation of vascular inflammation, senescence, TAA formation and survival in mice. The findings reveal that SIRT6 protects against TAA by epigenetically inhibiting vascular inflammation and senescence, providing insight into potential epigenetic strategies for TAA treatment.

The role of transforming growth factor beta in bicuspid aortic valve aortopathy

A bicuspid aortic valve (BAV) is the most prevalent congenital cardiac deformity, which is associated with an increased risk to develop a thoracic aortic aneurysm and/or an aortic dissection as compared to persons with a tricuspid aortic valve. Due to the high prevalence of a BAV in the general population and the associated life-long increased risk for adverse vascular events, BAV disease places a considerable burden on the public health. The aim of the present review is to discuss the role of transforming growth factor beta (TGF-β) signaling in the development of the vascular wall and on how this complex signaling pathway may be involved in thoracic aortic aneurysm formation in tricuspid and BAV patients.

Abstract 286: Identification Of Microrna Regulators Of Cell Signalling In Marfan Aorta Using Machine Learning

Marfan syndrome (MFS), due to FBN1 mutations, is associated with thoracic aortic aneurysm (TAA). The TGFß and other signalling pathways have been implicated in TAA formation, however, regulators of cell signalling in MFS are yet to be defined. We hypothesized that distinct microRNA (miRNA) expression profiles occur in MFS aorta and that these can illuminate novel cell signalling targets contributing to TAA. MiRNAs were extracted from MFS (n=15) and controls (n=11) ascending aortic tissue, for discovery open-array panel profiling of miRNA expression. Individual miRNA expression profiles were compared between MFS and controls by random forest machine learning algorithm (Python). The miRNAs identified with a significant importance value were selected for gene target prediction (score >90) through miRDB, followed by KEGG analysis. Any miRNA with more than 2000 predicted targets in the genome was excluded. P=0.05 was used as a cut-off value for KEGG analysis. The random forest classifier identified 53 miRNAs with differential expression between MFS and controls, contributing to the model (predictive accuracy 73%). The five most significant miRNAs were miR-181a-3p, miR-144-3p, miR-545-5p, miR-27a-5p and miR-181c-3p. 2984 unique target genes were identified from 53 significant miRNAs. KEGG analysis of these target genes identified multiple pathways as having potential differential regulation by miRNAs between MFS and controls. The most significant and relevant pathways identified were PI3K/AKT (p<0.00001) and the downstream FOXO (p<0.0004) pathways. Others include the MAPK (p<0.00001), mTOR (p<0.00002), RAP1 (p<0.005), ErbB (p<0.003) and RAS (p<0.001) pathways, in addition to TGFß (p<0.01). Mapping miRNA targets to KEGG pathways identified potential regulatory points, e.g., miR-29c-3p affecting FBN1, AKT3, PTEN (within the TGFß and PI3K/AKT pathways); miR-19a-3p affecting RAF1 , FMR1, RIN2 (within the MAPK, fragile X and adherens junction pathways); miR-27a-5p affecting LTBP1 (within the TGFß pathway). In conclusion, machine learning analysis identifies differential expression of multiple miRNAs in aortic tissue from MFS, which map to cell signalling pathways implicated in the pathogenesis of TAA in MFS.

Urate-Lowering Therapy Inhibits Thoracic Aortic Aneurysm and Dissection Formation in Mice.

Thoracic aortic aneurysm and dissection (TAAD) is a highly lethal vascular disease without effective drug therapy. Whether elevated serum concentrations of uric acid are involved in TAAD development remains unclear. Serum uric acid levels were detected in different TAAD mouse models and patients. The urate-lowering drug allopurinol was administered in the drinking water of TAAD mice. Adenine diet-induced mice were established to investigate the role of hyperuricemia in TAAD formation and RNA-sequencing of thoracic aortas from these mice was performed. We found serum uric acid levels were elevated in various mouse TAAD models, including mice fed a β-aminopropionitrile diet, Marfan mice with fibrillin-1 haploinsufficiency (Fbn1C1041G/+), and ApoE-/- mice infused with Ang II (angiotensin II), as well as in patients with TAAD. Administration of urate-lowering drug allopurinol in the drinking water significantly alleviated TAAD formation in β-aminopropionitrile-treated mice, Fbn1C1041G/+ mice, and Ang II-infused ApoE-/- mice. Moreover, an adenine diet was used to induce hyperuricemia in mice. Intriguingly, a 4-week adenine diet feeding directly induced TAAD formation characterized by increased maximal thoracic aortic diameters and severe elastin degradation, which were ameliorated by allopurinol. Unbiased RNA-sequencing in mouse thoracic aortas suggested that FcγR (Fc gamma receptor) was upregulated upon adenine diet, but reciprocally repressed by allopurinol. Mechanistically, hyperuricemia activated FcγR-mediated ERK1/2 (extracellular signal-regulated kinase 1/2) phosphorylation to induce macrophage inflammation and TAAD development, which was abrogated by allopurinol or FcγR deficiency. This study uncovered an important and previously unrecognized role of hyperuricemia in mediating the pathogenesis of TAAD, and uric acid-lowering drug may represent a promising therapeutic approach for TAAD.

340 The Effects of PTSD-Dependent Neurogenic Hypertension and Inflammation on Thoracic Aortic Aneurysm Progression

OBJECTIVES/GOALS: Nearly all thoracic aortic aneurysm patients suffer from hypertension leading to elevated wall tension and abnormal extracellular matrix remodeling. PTSD patients have higher blood pressure both at rest and in response to stimuli. Although stress is associated with cardiovascular disease, the exact mechanism linking the two is still unknown. METHODS/STUDY POPULATION: Adult C57BL/6 mice underwent a PTSD induction protocol consisting of inescapable foot shock followed by single prolonged stress. The mice were assessed incrementally for their PTSD-like phenotype using specific behavioral tests chosen to assess for each of the human criteria of PTSD according to the DSM-V. Tail cuff blood pressure measurements were taken serially throughout the 16-week protocol. At terminal study, thoracic aortic diameter measurements were obtained through digital microscopy and plasma was harvested for cytokine analysis. Thoracic aortic aneurysms (TAA) were induced through periadventitial application of a calcium chloride solution on the descending thoracic aorta in BPH/2J and BPN/3J adult mice. The thoracic aortic diameter was measured at terminal study through digital microscopy. RESULTS/ANTICIPATED RESULTS: Using our PTSD-like mouse model we have demonstrated that PTSD-like mice have significantly higher systolic blood pressure following a reminder of the traumatic event than control mice recapitulating the human phenotype. They also had increased plasma proinflammatory cytokines and larger thoracic aortic diameters than control mice. Although the increased thoracic aortic diameter is not an aneurysm, it suggests ECM remodeling is occurring predisposing the aorta to aneurysm formation. Finally, we have shown that in neurogenic hypertensive mice, TAA formation was accelerated by 12 weeks with roughly 70% dilation at 4 weeks post-TAA induction surgery as compared to roughly a 20% dilation in control mice. DISCUSSION/SIGNIFICANCE: Altogether, these studies reinforce the link between stress and TAA development, and our mouse model will allow for the underlying mechanism to be elucidated. Better understanding of the mechanism linking PTSD and TAA will allow for the creation of novel therapeutics to treat PTSD symptoms while also delaying TAA progression.

Targeting endothelial tight junctions to predict and protect thoracic aortic aneurysm and dissection.

Whether changes in endothelial tight junctions (TJs) lead to the formation of thoracic aortic aneurysm and dissection (TAAD) and serve as an early indicator and therapeutic target remains elusive. Single-cell RNA sequencing analysis showed aberrant endothelial TJ expressions in the thoracic aortas of patients with TAAD. In a β-aminopropionitrile (BAPN)-induced TAAD mouse model, endothelial TJ function was disrupted in the thoracic aortas at an early stage (5 and 10 days) as observed by a vascular permeability assay, while the intercellular distribution of crucial TJ components was significantly decreased by en face staining. For the non-invasive detection of endothelial TJ function, two dextrans of molecular weights 4 and 70 kDa were conjugated with the magnetic resonance imaging (MRI) contrast agent Gd-DOTA to synthesize FITC-dextran-DOTA-Gd and rhodamine B-dextran-DOTA-Gd. MRI images showed that both probes accumulated in the thoracic aortas of the BAPN-fed mice. Particularly, the mice with increased accumulated signals from 5 to 10 days developed TAAD at 14 days, whereas the mice with similar signals between the two time points did not. Furthermore, the protease-activated receptor 2 inhibitor AT-1001, which seals TJs, alleviated the BAPN-induced impairment of endothelial TJ function and expression and subsequently reduced TAAD incidence. Notably, endothelial-targeted ZO-1 conditional knockout increased TAAD incidence. Mechanistically, vascular inflammation and edema were observed in the thoracic aortas of the BAPN-fed mice, whereas these phenomena were attenuated by AT-1001. The disruption of endothelial TJ function is an early event prior to TAAD formation, herein serving as a potential indicator and a promising target for TAAD.

Early outcomes of valve preservation in patients with ascending aortic aneurysm and bicuspid valve disease

Background: Bicuspid aortic valve (BAV) is the most frequent congenital heart disease affecting 1% to 2% of the population, with thoracic aortic aneurysm (TAA) formation being its second most frequent complication after aortic valve dysfunction (stenosis or insufficiency). Aortic valve replacement (AVR) with mechanical or biologic prostheses has long been the procedure of choice. Although prosthetic AVR is effective in correcting the hemodynamic problem, there are important long-term drawbacks. These are particularly present in a younger patient population, such as the majority of individuals with a BAV. Patient and methods: 40 patients underwent aortic valve repair for bicuspid aortic valve disease with ascending aortic aneurysm in the period between June 2020 and February 2022 in Kasr Alainy hospitals. Results: All our patients showed significant improvement regarding left ventricular dimensions and contractility. Two patients had mild to moderate regurge and thirty eight patients had non-significant regurge in the six month follow up echo. One patient complicated by complete heart block required permanent pacemaker implantation, another two patients had postoperative high drainage required revision for bleeding. One patient died from ventilator associated pneumonia after prolonged mechanical ventilation due to disturbed conscious level.

HOXA cluster antisense RNA 2 elevates KIAA1522 expression through microRNA-520d-3p and insulin like growth factor 2 mRNA binding protein 3 to promote the growth of vascular smooth muscle cells in thoracic aortic aneurysm.

Recently, long non-coding RNAs (lncRNAs) have been revealed to mediate smooth muscle dysfunction in thoracic aortic aneurysm (TAA). LncRNA HOXA-AS2 has been proposed to engage in the regulation of diverse diseases. However, its function in TAA remains unknown. This study aimed to reveal the role and mechanism of HOXA-AS2 in VSMCs which were implicated in TAA formation. RT-qPCR or western blot was performed to detect RNA or protein expression levels. The role of HOXA-AS2 in VSMCs was explored by functional assays. The relationship among HOXA-AS2/miR-520d-3p/KIAA1522/IGF2BP3 was analysed via mechanism assays. HOXA-AS2 was detected to have significantly high expression in TAA tissues and function as an oncogene to promote proliferation of VSMCs, while inhibiting cell apoptosis (Figure 1, **P<0.01). HOXA-AS2 was unveiled to bind with miR-520d-3p (Figure 2, *P<0.05, **P<0.01) and further up-regulate KIAA1522 to facilitate the growth of VSMCs (Figure 3-4, *P<0.05, **P<0.01). HOXA-AS2 was also found to recruit IGF2BP3 to stabilize KIAA1522 mRNA (Figure 5, **P<0.01). All data were displayed as mean±standard deviation. HOXA-AS2 up-regulates KIAA1522 through targeting miR-520d-3p/IGF2BP3 to drive VSMC growth in TAA.

Dexamethasone attenuated thoracic aortic aneurysm and dissection in vascular smooth muscle cell Tgfbr2-disrupted mice with CCL8 suppression.

What is the central question of this study? What is the relationship of chemokine (C-C motif) ligand 8 (CCL8) to thoracic aortic aneurysm and dissection (TAAD) formation in postnatal mice with vascular smooth muscle cell (VSMC) Tgfbr2 disruption, and is dexamethasone a potential treatment? What is the main finding and its importance? CCL8 was associated with the formation of TAAD in VSMC Tgfbr2-disrupted mice. Dexamethasone reduced TAAD formation and inhibited mitogen-activated protein kinase (p-p38) and nuclear factor-κB (p-p65) signalling pathways. CCL8 might be an important promoter of aortic inflammation. Dexamethasone provided potential therapeutic effects in TAAD treatment. Aortic inflammation plays a vital role in initiation and progression of thoracic aortic aneurysm and dissection (TAAD). Disturbance of the transforming growth factor-β (TGF-β) signalling pathway is believed to be one of the pathogenic mechanisms of TAAD. Initially, Myh11-CreERT2 .Tgfbr2f/f male mice were used to build a TAAD mouse model, and bioinformatic analyses revealed enriched inflammatory signal pathways and upregulated chemokine (C-C motif) ligand 8 (CCL8). So we hypothesized that vascular smooth muscle cell (VSMC) Tgfbr2 disruption in postnatal mice results in aortic inflammation associated with CCL8 secretion. Real-time quantitative PCR and serum enzyme-linked immunosorbent assay (ELISA) results confirmed that CCL8 expression began to increase after VSMC Tgfbr2 disruption. Next, we cultured mouse thoracic aortas ex vivo, and observed that the protein expression of CCL8 in culture supernatants was increased by ELISA. Subsequently, the co-localization of CCL8 with α-smooth muscle actin or CD68 was found to be significantly increased by immunofluorescence. Then, dexamethasone (DEX) was used to treat TAAD in VSMC Tgfbr2-disrupted mice; the results of histochemical, immunofluorescence and immunohistochemical staining indicated that DEX therapy reduced CCL8 secretion, inflammatory cell recruitment, aortic medial thickening, elastic fibre fragmentation, extracellular matrix degradation and contractile apparatus impairment, and thereby ameliorated TAAD formation. Western blotting showed that mitogen-activated protein kinase and nuclear factor-κB signalling pathways in aorta were overactivated after VSMC Tgfbr2 disruption, but inhibited by DEX therapy. Altogether, CCL8 might be an important promoter in TAAD formation of VSMC Tgfbr2-disrupted mice, and DEX provided potential therapeutic effects in TAAD treatment.

Fibrillin-1-regulated miR-122 has a critical role in thoracic aortic aneurysm formation.

Thoracic aortic aneurysms (TAA) in Marfan syndrome, caused by fibrillin-1 mutations, are characterized by elevated cytokines and fragmentated elastic laminae in the aortic wall. This study explored whether and how specific fibrillin-1-regulated miRNAs mediate inflammatory cytokine expression and elastic laminae degradation in TAA. miRNA expression profiling at early and late TAA stages using a severe Marfan mouse model (Fbn1mgR/mgR) revealed a spectrum of differentially regulated miRNAs. Bioinformatic analyses predicted the involvement of these miRNAs in inflammatory and extracellular matrix-related pathways. We demonstrate that upregulation of pro-inflammatory cytokines and matrix metalloproteinasesis a common characteristic of mouse and human TAA tissues. miR-122, the most downregulated miRNA in the aortae of 10-week-old Fbn1mgR/mgR mice, post-transcriptionally upregulated CCL2, IL-1β and MMP12. Similar data were obtained at 70weeks of age using Fbn1C1041G/+ mice. Deficient fibrillin-1-smooth muscle cell interaction suppressed miR-122 levels. The marker for tissue hypoxia HIF-1α was upregulated in the aortic wall of Fbn1mgR/mgR mice, and miR-122 was reduced under hypoxic conditions in cell and organ cultures. Reduced miR-122 was partially rescued by HIF-1α inhibitors, digoxin and 2-methoxyestradiol in aortic smooth muscle cells. Digoxin-treated Fbn1mgR/mgR mice demonstrated elevated miR-122 and suppressed CCL2 and MMP12 levels in the ascending aortae, with reduced elastin fragmentation and aortic dilation. In summary, this study demonstrates that miR-122 in the aortic wall inhibits inflammatory responses and matrix remodeling, which is suppressed by deficient fibrillin-1-cell interaction and hypoxia in TAA.

Integrating Bulk Transcriptome and Single-Cell RNA Sequencing Data Reveals the Landscape of the Immune Microenvironment in Thoracic Aortic Aneurysms.

Thoracic aortic aneurysm (TAA) is a life-threatening cardiovascular disease whose formation is reported to be associated with massive vascular inflammatory responses. To elucidate the roles of immune cell infiltration in the pathogenesis underlying TAA, we utilized multiple TAA datasets (microarray data and scRNA-seq data) and various immune-related algorithms (ssGSEA, CIBERSORT, and Seurat) to reveal the landscapes of the immune microenvironment in TAA. The results exhibited a significant increase in the infiltration of macrophages and T cells, which were mainly responsible for TAA formation among the immune cells. To further reveal the roles of immunocytes in TAA, we inferred the intercellular communications among the identified cells of aortic tissues. Notably, we found that in both normal aortic tissue and TAA tissue, the cells that interact most frequently are macrophages, endothelial cells (ECs), fibroblasts, and vascular smooth muscle cells (VSMCs). Among the cells, macrophages were the most prominent signal senders and receivers in TAA and normal aortic tissue. These findings suggest that macrophages play an important role in both the physiological and pathological conditions of the aorta. The present study provides a comprehensive evaluation of the immune cell composition and reveals the intercellular communication among aortic cells in human TAA tissues. These findings improve our understanding of TAA formation and progression and facilitate the development of effective medications to treat these conditions.

Brucellosis relapse causing thoracic aortic ulcers and aneurysm formation: a case report

BackgroundBrucellosis is an infectious disease caused by Brucella spp, which can involve the cardiovascular, digestive, and respiratory systems. Cardiovascular involvement is a rare occurrence, it has an extremely high mortality rate.Case presentationA 67-year-old Chinese man presented with thoracic aortic multiple ulcers and partial aneurysm formation that caused symptoms of left waist and left buttock pain. The man was admitted to our hospital due to abdominal aorta pseudoaneurysms 5 years ago. The diagnosis was made by thoracic computed tomography angiography (CTA), previous history, and positive culture of Brucella, and the patient was successfully treated by thoracic aortic covered stent-graft implantation and specific medical treatment.ConclusionsPeople who have a history of contact with cattle and sheep, should beware of the possibility of Brucella infection. If chest and abdominal pain occur, timely medical treatment is recommended, aortic aneurysm, the disease with a high risk of death, can be identified or excluded by CTA. Early treatment and prevention of disease progression are more beneficial to patients.

Vitamin B Mitigates Thoracic Aortic Dilation in Marfan Syndrome Mice by Restoring the Canonical TGF-β Pathway.

Thoracic aortic aneurysm (TAA) formation is a multifactorial process that results in diverse clinical manifestations and drug responses. Identifying the critical factors and their functions in Marfan syndrome (MFS) pathogenesis is important for exploring personalized medicine for MFS. Methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR), and methionine synthase reductase (MTRR) polymorphisms have been correlated with TAA severity in MFS patients. However, the detailed relationship between the folate-methionine cycle and MFS pathogenesis remains unclear. Fbn1C1039G/+ mice were reported to be a disease model of MFS. To study the role of the folate-methionine cycle in MFS, Fbn1C1039G/+ mice were treated orally with methionine or vitamin B mixture (VITB), including vitamins B6, B9, and B12, for 20 weeks. VITB reduced the heart rate and circumference of the ascending aorta in Fbn1C1039G/+ mice. Our data showed that the Mtr and Smad4 genes were suppressed in Fbn1C1039G/+ mice, while VITB treatment restored the expression of these genes to normal levels. Additionally, VITB restored canonical transforming-growth factor β (TGF-β) signaling and promoted Loxl1-mediated collagen maturation in aortic media. This study provides a potential method to attenuate the pathogenesis of MFS that may have a synergistic effect with drug treatments for MFS patients.

Basigin genetic depletion reduces thoracic aortic aneurysm formation in marfan syndrome mice

Abstract Background Marfan Syndrome (MFS) is a rare genetic disease due to mutations in fibrillin 1 gene [1]. It is characterized by thoracic aortic aneurysm (TAA), whose dissection is the major cause of morbidity and mortality in MFS patients [2]. While pathological mechanisms underlying MFS extracellular matrix remodelling have started to be elucidated, an etiological treatment is not available yet [3,4]. Recently, EMMPRIN has been proposed as new actor in pro-fibrotic processes associated with TAA development in MFS patients [4,5]. Purpose To confirm the role of EMMPRIN (i.e. Basigin in mice, Bsg) in TAA formation and progression in a preclinical setting, we assessed whether Bsg genetic depletion in a mouse model of MFS (Fbn1C1039G/+) [6] had an impact on aortic phenotype. Methods We generated a double transgenic mouse model, Fbn1C1039G/+-Bsg+/−, by crossing commercially available Fbn1C1039G/+ with Bsg+/− mice (provided by Dr. Kadomatsu) [7] and we prospectively measured aortic root size in 12 Fbn1C1039G/+-Bsg+/−, 9 Fbn1C1039G/+, and 15 WT mice every 4 weeks from 12 to 20 weeks of age by 2D-echocardiography. Both qRT-PCR and Western Blot were used to evaluate EMMPRIN downstream pro-fibrotic pathway activation in thoracic aortic tissue obtained from mice sacrificed at 12 weeks. Plasma soluble EMMPRIN (sEMMPRIN) levels were assessed by ELISA. Results Echocardiographic assessment at 12 and 20 weeks of age confirmed significantly dilated aortic root in Fbn1C1039G/+ vs WT (mean±SD at 12 weeks: 1.772±0.081 vs 1.394±0.068 mm, respectively, p&amp;lt;0.0001; 20 weeks: 1.899±0.103 vs 1.520±0.083 mm, respectively, p&amp;lt;0.0001), and revealed that Fbn1C1039G/+-Bsg+/− mice had lower aortic root diameter extent compared to Fbn1C1039G/+ (12 weeks: 1.667±0.109 vs 1.772±0.081 mm, respectively, p=0.026; 20 weeks: 1.752±0.129 vs 1.899±0.103 mm, respectively, p=0.011). Pro-fibrotic gene profiling in a subset of 12 weeks old mice showed that Col1A1, Col3A1 and FN1 genes were more expressed in Fbn1C1039G/+ than in WT mice and that the up-regulation of these genes was mitigated in Fbn1C1039G/+ by Bsg depletion (ANOVA p=0.048, p=0.055, and p=0.0003, respectively). Moreover, we found a significant activation of the EMMPRIN downstream pro-fibrotic ERK1/2 pathway in Fbn1C1039G/+ compared to WT mice which was attenuated in the Fbn1C1039G/+-Bsg+/− model (p=0.030). Plasma sEMMPRIN levels were lower in Fbn1C1039G/+ than in WT mice, consistent with what we previously observed in MFS patients [5], and decreased over time in both Fbn1C1039G/+ and WT mice (2-way ANOVA disease p=0.013, time p=0.012, interaction p=ns). Conclusions Basigin genetic depletion reduces dilatation of the aortic root and pro-fibrotic pathway activation in a preclinical MFS model, confirming previous proof-of-concept findings and paving the way for the development of innovative therapies for MFS patients. Plasma sEMMPRIN levels stand as promising tool to predict the aortic enlargement progression in MFS models and patients. Funding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): Italian Ministery of Health

Abstract P105: Inducible Deletion Of Fibrillin-1 In Smooth Muscle Cells Has Modest Effects On Thoracic Aortic Dilatation In Adult Mice

Introduction: Fibrillin-1 ( Fbn1 ) mutations are associated with thoracic aortic aneurysms (TAAs) in patients with Marfan syndrome. Constitutive deletion of Fbn1 leads to neonatal death due to aortic rupture in mice. However, the role of Fbn1 in maintaining aortic integrity during the adult phase remains unclear. Since smooth muscle cell (SMC) is a major constituent of the aortic media, this study examined whether deletion of Fbn1 in SMCs of adult mice leads to compromise of aortic integrity. Methods and Results: Fbn1 floxed mice were generated that included insertion of tdTomato as a reporter for gene deletion. Female Fbn1 floxed mice were bred with male Fbn1 floxed mice expressing CreER T2 driven by an Acta2 promotor. Tamoxifen was injected intraperitoneally for 5 days into male Fbn1 floxed littermate mice that were either Cre negative or positive (n=6-8/genotype, 5-week-old) to create sm Fbn1 +/+ and -/- mice, respectively. Gene recombination was confirmed by the presence of tdTomato in sm Fbn1 -/- mice using PCR and confocal microscopy. To investigate the impact of SMC-specific Fbn1 deletion, male sm Fbn1 +/+ and -/- littermates terminated at two intervals, 5 and 36 weeks after completion of tamoxifen injections. In situ aortic images were captured, and aortic diameters were measured at ascending, arch, and descending thoracic aortas. Five weeks after tamoxifen injection, aortic diameters of smFbn1+/+ and -/- mice were not different. Despite the long-term deletion of Fbn1 in SMCs, aortic dilatation was not observed in any regions of aortas in sm Fbn1 -/- mice compared to wild type littermates 36 weeks after tamoxifen injection. Next, we investigated whether Fbn1 deletion in SMCs augmented angiotensin II (AngII)-induced aortic dilatation. AngII was infused subcutaneously into male sm Fbn1 +/+ and -/- littermates for 12 weeks (n=11-12/genotype), started 2weeks after completion of tamoxifen injections. AngII-induced aortic dilatations were augmented modestly by SMC-specific Fbn1 deletion (+/+ 1.7±0.0, -/- 1.9±0.1 mm, P=0.047). Conclusion: Deletion of Fbn1 in SMCs did not cause spontaneous TAA formation and had modest effects on AngII-induced TAAs in adult mice. Fbn1 in SMCs does not exert a critical role in mice after the aortic structure has formed.