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The current understanding of the genetic determinants of thoracic aortic aneurysms and dissections (TAAD) has largely been informed through studies of rare, Mendelian forms of disease. Here, we conducted a genome-wide association study (GWAS) of TAAD, testing ~25 million DNA sequence variants in 8,626 participants with and 453,043 participants without TAAD in the Million Veteran Program, with replication in an independent sample of 4,459 individuals with and 512,463 without TAAD from six cohorts. We identified 21 TAAD risk loci, 17 of which have not been previously reported. We leverage multiple downstream analytic methods to identify causal TAAD risk genes and cell types and provide human genetic evidence that TAAD is a non-atherosclerotic aortic disorder distinct from other forms of vascular disease. Our results demonstrate that the genetic architecture of TAAD mirrors that of other complex traits and that it is not solely inherited through protein-altering variants of large effect size. A genome-wide association study of thoracic aortic aneurysms and dissections (TAAD) in the Million Veteran Program identifies 17 new risk loci and demonstrates that the genetic architecture of TAAD mirrors that of other complex traits.

Ascending thoracic aortic aneurysm (ATAA) remains a significant medical concern, with its asymptomatic nature posing diagnostic and monitoring challenges, thereby increasing the risk of aortic wall dissection and rupture. Current management of aortic repair relies on an aortic diameter threshold. However, this approach underestimates the complexity of aortic wall disease due to important knowledge gaps in understanding its underlying pathologic mechanisms.Since traditional risk factors cannot explain the initiation and progression of ATAA leading to dissection, local vascular factors such as extracellular matrix (ECM) and vascular smooth muscle cells (VSMCs) might harbor targets for early diagnosis and intervention. Derived from diverse embryonic lineages, VSMCs exhibit varied responses to genetic abnormalities that regulate their contractility. The transition of VSMCs into different phenotypes is an adaptive response to stress stimuli such as hemodynamic changes resulting from cardiovascular disease, aging, lifestyle, and genetic predisposition. Upon longer exposure to stress stimuli, VSMC phenotypic switching can instigate pathologic remodeling that contributes to the pathogenesis of ATAA.This review aims to illuminate the current understanding of cellular and molecular characteristics associated with ATAA and dissection, emphasizing the need for a more nuanced comprehension of the impaired ECM–VSMC network.

Thoracic aortic aneurysm and dissection (TAAD) affects many patients globally and has high mortality rates if undetected. Once thought to be solely a degenerative disease that afflicted the aorta due to high pressure and biomechanical stress, extensive investigation of the heritability and natural history of TAAD has shown a clear genetic basis for the disease. Here, we review both the cellular mechanisms and clinical manifestations of syndromic and non-syndromic TAAD. We particularly focus on genes that have been linked to dissection at diameters <5.0 cm, the current lower bound for surgical intervention. Genetic screening tests to identify patients with TAAD associated mutations that place them at high risk for dissection are also discussed.

Genetic factors are fundamental in the etiology of thoracic aortic aneurysm and dissection (TAAD), but the genetic cause is detected in only about 30% of cases. To define unreported TAAD-associated sequence variants, exome and gene panel sequencing was performed in 323 patients. We identified heterozygous CDKL1 variants [c.427T>C p.(Cys143Arg), c.617C>T p.(Ser206Leu), and c.404C>T p.(Thr135Met)] in 6 patients from 3 families with TAAD spectrum disorders. CDKL1 encodes a protein kinase involved in ciliary biology. Amino acid substitutions were predicted to affect CDKL1 catalytic activity or protein binding properties. CDKL1 was expressed in vascular smooth muscle cells in normal and diseased human aortic wall tissue. Cdkl1 knockdown and transient knockout in zebrafish resulted in intersomitic vessel (ISV) malformations and aortic dilation. Coinjection of human CDKL1wild-type RNA, but not CDKL1Cys143Arg and CDKL1Ser206Leu RNA, rescued ISV malformations. All variants affected CDKL1 kinase function and profiling data, and altered protein-protein binding properties, particularly with ciliary transport molecules. Expression of CDKL1 variants in heterologous cells interfered with cilia formation and length, CDKL1 localization, and p38 MAPK and Vegf signaling. Our data suggest a role of CDKL1 variants in the pathogenesis of TAAD spectrum disorders. The association between primary cilia dysregulation and TAAD expands our knowledge of the underlying molecular pathophysiology.

Enlargement of the aorta is an important risk factor for aortic aneurysm and dissection, a leading cause of morbidity in the developed world. Here we performed automated extraction of ascending aortic diameter from cardiac magnetic resonance images of 36,021 individuals from the UK Biobank, followed by genome-wide association. We identified lead variants across 41 loci, including genes related to cardiovascular development ( HAND2 , TBX20 ) and Mendelian forms of thoracic aortic disease ( ELN , FBN1 ). A polygenic score significantly predicted prevalent risk of thoracic aortic aneurysm and the need for surgical intervention for patients with thoracic aneurysm across multiple ancestries within the UK Biobank, FinnGen, the Penn Medicine Biobank and the Million Veterans Program (MVP). Additionally, we highlight the primary causal role of blood pressure in reducing aortic dilation using Mendelian randomization. Overall, our findings provide a roadmap for using genetic determinants of human anatomy to understand cardiovascular development while improving prediction of diseases of the thoracic aorta. Trans-ancestry genome-wide analyses identify multiple loci associated with ascending aortic diameter. A polygenic score constructed from these loci predicted prevalent risk of thoracic aortic aneurysm in independent populations.

The mechanism by which aging induces aortic aneurysm and dissection (AAD) remains unclear. A total of 430 participants were recruited for the screening of differentially expressed plasma microRNAs (miRNAs). We found that miR-1204 is significantly increased in both the plasma and aorta of elder patients with AAD and is positively correlated with age. Cell senescence induces the expression of miR-1204 through p53 interaction with plasmacytoma variant translocation 1, and miR-1204 induces vascular smooth muscle cell (VSMC) senescence to form a positive feedback loop. Furthermore, miR-1204 aggravates angiotensin II-induced AAD formation, and inhibition of miR-1204 attenuates β-aminopropionitrile monofumarate-induced AAD development in mice. Mechanistically, miR-1204 directly targets myosin light chain kinase (MYLK), leading to the acquisition of a senescence-associated secretory phenotype (SASP) by VSMCs and loss of their contractile phenotype. MYLK overexpression reverses miR-1204-induced VSMC senescence, SASP and contractile phenotypic changes, and the decrease of transforming growth factor-β signaling pathway. Our findings suggest that aging aggravates AAD via the miR-1204-MYLK signaling axis. How aging induces aortic aneurysm and dissection (AAD) remains unclear. Here, the authors show that aging induces miR-1204 to inhibit MYLK, promoting vascular smooth muscle cells to acquire senescence-associated secretory phenotype, resulting in vascular inflammation, and the aggravation of AAD formation.

Metabolic disturbances are hallmarks of vascular smooth muscle cell (VSMC) phenotypic transitions, which play a critical role in the pathogenesis of aortic dissection (AD). In this study, we identify and characterize glucose metabolism regulatory protein (GMRSP), a protein encoded by lncRNA H19. Using VSMC-specific GMRSP induction in knock-in mice, adeno-associated virus-mediated GMRSP overexpression, and exosomal GMRSP delivery, we demonstrate significant improvements in AD and mitochondrial dysfunction. Mechanistically, GMRSP inhibits heterogeneous nuclear ribonucleoprotein (hnRNP) A2B1-mediated alternative splicing of pyruvate kinase M (PKM) pre-mRNA, leading to reduced PKM2 production and glycolysis. This reprogramming preserves the contractile phenotype of VSMCs and prevents their transition to a proliferative state. Importantly, pharmacological activation of PKM2 via TEPP-46 abrogates the protective effects of GMRSP in vivo and in vitro. Clinical relevance is shown by elevated plasma PKM2 levels in AD patients, which correlate with poor prognosis. Collectively, these findings indicate GMRSP as a key regulator of VSMC metabolism and phenotypic stability, highlighting its potential as a therapeutic target for AD. Metabolic dysfunction is an important characteristic of vascular smooth muscle cells (VSMCs) phenotypic transition in aortic dissection. Here, the authors show lncRNA H19 could encode a peptide, GMRSP. GMRSP regulates the glycolysis by counteracting hnRNP A2B1-mediated pyruvate kinase M pre-mRNA alternative splicing and control the phenotypic transition of VSMCs.

Marfan syndrome (MFS) is an inherited connective tissue disorder, with aortic root aneurysm and/or dissection being the most severe and life-threatening complication. These conditions have been linked to pathogenic variants in the FBN1 gene and dysregulated TGFβ signaling. Our objective was to evaluate the mRNA expression of FBN1, TGFBR1, TGFBR2, and TGFB2 in aortic tissue from MFS patients undergoing surgery for aortic dilation. This prospective study (2014–2023) included 20 MFS patients diagnosed according to the 2010 Ghent criteria, who underwent surgery for aneurysm or dissection based on Heart Team recommendations, along with 20 non-MFS controls. RNA was extracted, and mRNA levels were quantified using RT-qPCR. Patients with dissection showed significantly higher FBN1 mRNA levels [79 (48.1–110.1)] compared to controls [37.2 (25.1–79)] (p = 0.03). Conversely, TGFB2 expression was significantly lower in MFS patients [12.17 (6.54–24.70)] than in controls [44.29 (25.85–85.36)] (p = 0.029). A positive correlation was observed between higher FBN1 expression and a larger sinotubular junction diameter (r = 0.42, p = 0.07), while increased FBN1 expression was particularly evident in MFS patients with dissection. Additionally, TGFB2 expression showed an inverse correlation with ascending aortic diameter (r = 0.53, p = 0.01). In aortic tissue, we found decreased TGFB2 and receptor levels alongside increased FBN1 mRNA levels. These molecular alterations may reflect compensatory mechanisms in response to tissue damage caused by mechanical stress, leading to dysregulation of physiological signaling pathways and ultimately contributing to aortic dilation in MFS.

Familial thoracic aortic aneurysm and dissection (FTAAD), caused by the pathogenic Myh11 K1256del variant, is characterized by impaired aortic contractility; however, how reduced contractility predisposes the aorta to dissection remains incompletely understood. In this study, we performed a data-driven trans-omic upstream analysis using Genome Enhancer to identify key regulatory mechanisms in aortas from Myh11 K1256del mice under baseline conditions, without exposure to exogenous pathological stimuli. Transcriptome analysis revealed enrichment of genes related to smooth muscle contraction and regulation of myosin light chain phosphatase activity. Upstream computational analysis of regulatory regions identified nuclear factor of activated T cells 1 and lymphoid enhancer-binding factor 1 as major transcription factors, and further highlighted Rho-associated, coiled-coil-containing protein kinase 1 (ROCK1) as a predicted central regulator of the dysregulated transcriptional network. Druggability analysis suggested ROCK1 and the JunB proto-oncogene AP-1 transcription factor subunit as potential therapeutic targets. Furthermore, it predicted 51 candidate therapeutants, including atorvastatin, GSK-269962A, and atovaquone. These findings indicate that even in the absence of overt pathological stimulation, aortic tissue carrying the Myh11 K1256del variant exhibits a transcriptional program centered on ROCK signaling, which may prime the aorta for maladaptive responses to additional stress and may enhance susceptibility to dissection. This computational analysis requires experimental validation, but may provide a hypothesis-generating framework for development of preventive pharmacological interventions against FTAAD.

Background Thoracic aortic dissection (TAD) is an irreversible cardiovascular disorder with high mortality and morbidity. However, the molecular mechanisms remain elusive. Thus, identifying an effective therapeutic target to prevent TAD is especially critical. The purpose of this study is to elucidate the potential mechanism of inflammation and vascular smooth muscle cell (VSMCs) phenotypic switch in β-aminopropionitrile fumarate (BAPN)-induced TAD. Methods A mouse model of TAD induced by BAPN and IL-1β -stimulated HVSMCs in vivo and in vitro models, respectively. ACE2 Knockdown mice treated with BAPN or without, and the TAD mouse model was treated with or without AAV-ACE2. Transthoracic ultrasound was conducted for assessment the maximum internal diameter of the thoracic aorta arch. RNA sequencing analysis was performed to recapitulate transcriptome profile changes. Western blot were used to detect the expression of MMP2, MMP9, ACE2, SIRT3, OPN, SM22α and other inflammatory markers. The circulating levels of ACE2 was measured by ELISA assay. Histological changes of thoracic aorta tissues were assessed by H&E, EVG and IHC analysis. Results We found that circulating levels of and the protein levels of ACE2 were increased in the TAD mouse model and in patients with TAD. For further evidence, ACE2 deficiency decelerated the formation of TAD. However, overexpression of ACE2 aggravated BAPN-induced aortic injury and VSMCs phenotypic switch via lowered SIRT3 expression and elevated inflammatory cytokine expression. Conclusion ACE2 deficiency prevented the development of TAD by inhibiting inflammation and VSMCs phenotypic switch in a SIRT3-dependent manner, suggesting that the ACE2/SIRT3 signaling pathway played a pivotal role in the pathological process of TAD and might be a potential therapeutical target. Highlights This study demonstrated for the first time that ACE2 deficiency attenuates the development of TAD induced by BAPN. The inhibitory effect of ACE2 deficiency on phenotypic transformation of VSMCs and inflammation may be through SIRT3 signaling pathway. Specific inhibition of SIRT3 can speed the exacerbation of TAD induced by BAPN and SIRT3 may be an important target for drug therapy of TAD.