Loss-of-function mutations in TGFB2 cause a syndromic presentation of thoracic aortic aneurysm

Recommendations for Design, Execution, and Reporting of Studies on Experimental Thoracic Aortopathy in Preclinical Models

There is a recent dramatic increase in research on thoracic aortic diseases that includes aneurysms, dissections, and rupture. Experimental studies predominantly use mice in which aortopathy is induced by chemical interventions, genetic manipulations, or both. Many parameters should be deliberated in experimental design in concert with multiple considerations when providing dimensional data and characterization of aortic tissues. The purpose of this review is to provide recommendations on guidance in (1) the selection of a mouse model and experimental conditions for the study, (2) parameters for standardizing detection and measurements of aortic diseases, (3) meaningful interpretation of characteristics of diseased aortic tissue, and (4) reporting standards that include rigor and transparency.

Intrinsic disorder in protein interaction networks linking cancer with metabolic diseases

Complex diseases are usually driven by numerous proteins that operate as intricate network systems. Deciphering of their signals is required for more advanced level understanding of the cellular processes driven by protein interactions. Therefore, placing diseases into a framework, where they can be viewed together, represents an important and fruitful approach. The goal of this study was to assess the intrinsic disorder present in the proteins forming PPI networks linking cancer with different human diseases. To this end, we used a set of bioinformatics tools to explore intrinsic disorder and liquid-liquid phase separation predispositions of 340 proteins reported earlier by Hirsch et al. (Cancer Cell (2010) 17(4), 348-361; doi: 10.1016/j.ccr.2010.01.022) as differently expressed in common chronic diseases, such as cancer, obesity, diabetes, and cardiovascular diseases. We further examined selected proteins from this set for their interactability and intrinsic disorder-based functionality. Our analyses demonstrated that intrinsically disordered proteins and proteins with intrinsically disordered regions may act as active network promoters and operate as highly connected hubs, which further enables them to play key roles in the disease pathways. The study also indicated that differently expressed proteins involved in disease progression could be characterized by diverse degrees of intrinsic disorder and LLPS propensity. We hope that our findings in combination with the outputs of the proteomic and functional genomic analyses contain essential clues that can be used in further medical research leading to the design of better therapies.

Distinctive Amelogenesis Imperfecta in Loeys-Dietz Syndrome Type II

Loeys-Dietz syndrome (LDS1-6) is caused by mutations along the transforming growth factor-β (TGF-β) signaling pathway and features aortic aneurysms and craniofacial dysmorphology. Mutations that cause LDS can be found in the genes encoding transforming growth factor-β (TGF-β) ligands (TGFB2 and TGFB3), receptors (TGFBR1 and TGFBR2), and signal transducers (SMAD2 and SMAD3). Variable enamel anomalies are seen in patients with LDS, but the most severe enamel defects with advanced attrition have been observed specifically in some patients with mutation in the TGFBR2 gene (LDS2). We used human specimens as well as a mouse model to further characterize enamel defects in LDS2 and to investigate the mechanism that leads to this phenotype. Deciduous teeth from patients with LDS2 exhibited normal enamel thickness, normal or localized reduction in enamel mineral density, impaired enamel ultrastructure, and impaired biomechanical properties, with some changes likely associated with environmental and systemic effects. Mice with mutation in the Tgfbr2 gene exhibited no significant changes in the amount of enamel produced or degree of mineralization. However, they presented with unique disruption of enamel rod decussation (crisscross pattern), resulting in impaired biomechanical properties. This phenotype is caused by impaired coordinated movement of ameloblasts (enamel-producing cells) during matrix deposition. Molecular analyses revealed that mutation in Tgfbr2 in ameloblasts does not significantly affect pSMAD2/3 levels in vivo and has a minimal effect on gene expression in the enamel organ when compared with the aorta, in which hundreds of genes were differentially expressed and consistent with aortic aneurysm. However, we identified changes in the distribution and activation of the metastasis suppressor NDRG1, Rac1/Cdc42, and Myosin II that appear consistent with the disruption of ameloblast coordinated movement, although the exact mechanism through which mutation in Tgfbr2 causes this unique enamel phenotype remains to be elucidated.

Abdominal Aortic Aneurysm and Liver Fibrosis: Clinical Evidence and Molecular Pathomechanisms

To stimulate further research, this review summarizes studies linking liver fibrosis with the risk of abdominal aortic aneurysms (AAA). AAA is defined as a permanently weakened and dilated abdominal aorta, which develops due to inflammation of the tunica media, activation of the renin-angiotensin-aldosterone system, immune system activation, and coagulation disorders. Typically asymptomatic, AAA is often incidentally detected through imaging done for abdominal symptoms or as part of screening programs. AAA follows a variable course and has a mortality rate strongly dependent on age and sex. Risk factors for AAA include age, male sex, ethnicity, family history of AAA, lifestyle habits, arterial hypertension, dyslipidemia, and comorbid atherosclerotic cardiovascular disease. Conversely, individuals with type 2 diabetes, female sex, and certain ethnicities are at a reduced risk of AAA. Liver fibrosis, resulting from chronic liver diseases owing to varying etiologies, is increasingly recognized as a potential contributor to AAA development. Evidence increasingly indicates that metabolic dysfunction-associated steatotic liver disease (MASLD) and other chronic liver conditions may intensify inflammatory pathways shared with AAA, thereby potentially exacerbating AAA progression. This review specifically examines the epidemiology and risk factors associated with the link between AAA and liver fibrosis. It also highlights potential pathomechanisms, including systemic inflammation, oxidative stress, and extracellular matrix remodeling, which may contribute to both conditions. Although these findings underscore significant overlaps in risk profiles, additional research is needed to clarify whether type 2 diabetes, female sex, and certain ethnicities truly confer protection against AAA or if this association is influenced by other confounding variables. Ultimately, addressing these open questions will help guide targeted therapeutic interventions and the identification of novel biomarkers to predict disease progression.

Mechanisms of aortic dissection: From pathological changes to experimental and in silico models

Aortic dissection continues to be responsible for significant morbidity and mortality, although recent advances in medical data assimilation and in experimental and in silico models have improved our understanding of the initiation and progression of the accumulation of blood within the aortic wall. Hence, there remains a pressing necessity for innovative and enhanced models to more accurately characterize the associated pathological changes. Early on, experimental models were employed to uncover mechanisms in aortic dissection, such as hemodynamic changes and alterations in wall microstructure, and to assess the efficacy of medical implants. While experimental models were once the only option available, more recently they are also being used to validate in silico models. Based on an improved understanding of the deteriorated microstructure of the aortic wall, numerous multiscale material models have been proposed in recent decades to study the state of stress in dissected aortas, including the changes associated with damage and failure. Furthermore, when integrated with accessible patient-derived medical data, in silico models prove to be an invaluable tool for identifying correlations between hemodynamics, wall stresses, or thrombus formation in the deteriorated aortic wall. They are also advantageous for model-guided design of medical implants with the aim of evaluating the deployment and migration of implants in patients. Nonetheless, the utility of in silico models depends largely on patient-derived medical data, such as chosen boundary conditions or tissue properties. In this review article, our objective is to provide a thorough summary of medical data elucidating the pathological alterations associated with this disease. Concurrently, we aim to assess experimental models, as well as multiscale material and patient data-informed in silico models, that investigate various aspects of aortic dissection. In conclusion, we present a discourse on future perspectives, encompassing aspects of disease modeling, numerical challenges, and clinical applications, with a particular focus on aortic dissection. The aspiration is to inspire future studies, deepen our comprehension of the disease, and ultimately shape clinical care and treatment decisions.

Genotype-Phenotype Correlation Insights Through Molecular Modeling Analysis in a Patient with Loeys-Dietz Syndrome

BACKGROUND

Pathogenic variants within the gene encoding transforming growth factor β (TGF-β) are responsible for Loeys-Dietz syndrome (LDS), a heritable thoracic aortic disease sharing clinical features with Marfan syndrome, including craniofacial and skeletal abnormalities as well as aortic root aneurysms and dissections. In contrast to Marfan syndrome patients, who rarely develop aneurysms or dissections beyond the aortic root, LDS patients frequently exhibit vessel aneurysms in locations other than the aortic root. Here, we report the case of a 61-year-old patient who initially presented with marfanoid characteristics and an aortic root aneurysm and was presumed to have Marfan syndrome two decades ago. Later, the patient developed an abdominal aorta aneurysm, necessitating endovascular repair and stent placement. That fact raised doubts regarding the initial diagnosis of Marfan syndrome, and we decided to investigate the genetic cause of the disorder.

METHODS

Genetic testing was performed using WES analysis and Sanger sequencing.

RESULTS

The genetic analysis detected a de novo heterozygous pathogenic variant c.896G>A in exon 5 of the TGFB2 gene, resulting in the amino acid substitution p. Arg299Gln that has devastating destabilizing structural effects on 3D folding of the protein, as demonstrated by the molecular modeling study we performed. This variant is pathogenic for LDS type 4, partially consistent with the patient's clinical presentation.

CONCLUSIONS

Our case emphasizes the significance of precise clinical assessment and genetic verification in patients exhibiting marfanoid characteristics. Furthermore, our findings contribute to the understanding of the diverse clinical spectrum associated with this specific pathogenic variant of TGFB2, underscoring the importance of detailed clinical assessment in expanding knowledge of genotype-phenotype correlations. Accurate diagnosis is crucial for tailored and appropriate management of individuals with heritable thoracic aortic diseases.

TGFBR3 dependent mechanism of TGFB2 in smooth muscle cell differentiation and implications for TGFB2-related aortic aneurysm

INTRODUCTION

Pathogenic variants in canonical transforming growth factor β (TGFβ) signaling genes predispose patients to thoracic aortic aneurysm and dissection (TAAD), predominantly in aortic root. Although TAAD pathogenesis associated with TGFβ receptor defects is well characterized, distinct and redundant mechanisms of TGFβ isoforms in TAAD incidence and severity remain elusive.

OBJECTIVE

Here we examined the biological role of TGFB2 in smooth muscle cell (SMC) differentiation and investigated how TGFB2 defects can lead to regional TAAD manifestations.

METHODS

To characterize the role of TGFB2 in SMC differentiation and function, we employed human-induced pluripotent stem cell (hiPSC)-derived SMC differentiation, CRISPR/Cas9 gene editing, three-dimensional SMC constructs, and human aortic tissue samples.

RESULTS

Despite the similar effects of different TGFβ isoforms on hiPSC-derived SMC differentiation, siRNA experiments revealed that TGFB2 distinctively displays TGFBR3 dependence for signal transduction, an understudied TGFβ receptor in TAAD. Molecular evaluation of different thoracic aorta regions suggested TGFB2 and TGFBR3 enrichment in the aortic root tunica media. TGFB2 haploinsufficiency (TGFB2KO/+) and TGFB2 neutralization impaired the differentiation of second heart field-derived SMCs. TGFBR3KO/KO prevented the molecular rescue of TGFB2KO/+ by TGFB2 supplementation indicating the involvement of TGFBR3 in TGFB2-mediated SMC differentiation. Lastly, a missense TGFB2 variant (TGFB2G276R/+) caused mechanical defects in SMC tissue ring constructs that were rescued by TGFB2 supplementation or genetic correction.

CONCLUSION

Our data suggests the distinct regulation and action of TGFB2 in SMCs populating the aortic root, while redundant activities of TGFβ isoforms provide implications about the milder TAAD aggressiveness of pathogenic TGFB2 variants.

The genetics of hyper IgE syndromes

Hyper IgE syndromes (HIES) form a rare group of primary immunodeficiency disorders (PIDs) distinguished by persistent skin abscesses, dermatitis, allergies, and infections, in addition to their characteristic high serum IgE levels. Autosomal dominant (AD) and autosomal recessive (AR) genetic defects have been reported in HIES. From a clinical perspective, AD-HIES cases generally exhibit several non-immunologic features, including connective tissue, dental and skeletal abnormalities, whilst AR-HIES conditions have a higher incidence of neurologic complications and cutaneous viral infections. Genetic defects associated with HIES lead to impaired immune signaling, affecting pathways crucial for immune cell development, function, and immune response to pathogens/allergens. As a result, HIES patients are predisposed to recurrent bacterial and/or fungal infections, as well as atopic allergic responses. In many cases, the exact biological mechanisms responsible for the variations observed in the clinical phenotypes between the two inherited forms of HIES are still unclear. In this review, we describe the genetic basis of HIES with a distinction between the AR-HIES and AD-HIES forms, to better comprehend the different underlying molecular mechanisms, a distinction which is imperative for the accurate diagnosis, management, and development of targeted therapies for HIES patients.

Two-staged repair of a giant iliac aneurysm and open repair of a true deep femoral artery aneurysm in Loeys-Dietz syndrome type V: a case report and review of literature

BACKGROUND

The syndrome of Loeys-Dietz (LDS) is a rare connective tissue disorder. A classic triad of symptoms is seen: hypertelorism, atypical uvula or clef palate, and multiple tortuous arteries and aneurysms of the aorta and main arterial branches. Mutations in genes involving the transforming growth factor-beta (TGFB) signaling pathway are the cause of this syndrome. There are six subtypes of LDS, categorized based on the gene mutation that is involved. LDS type V and VI, concerning the TGFB3 and SMAD2 gene respectively, are the two subtypes that are least frequently seen. Mostly, in the patients with LDS type V non-cardiovascular symptoms are most prominent and there is a lower prevalence of vascular abnormalities.

METHODS AND RESULTS

This case report illustrates extensive vascular disease in Loeys-Dietz syndrome type V. We present open repair of a true deep femoral artery aneurysm and two-staged repair of a giant common iliac aneurysm with coiling of an ipsilateral internal iliac artery aneurysm and subsequent endovascular aortic repair (EVAR).

CONCLUSION

Loeys-Dietz syndrome type V is a rare connective tissue disorder, that was thought to have non-cardiovascular symptoms at the forefront. However, this case represents multiple vascular abnormalities, including arterial tortuosity and iliac and femoral artery aneurysms, as the main symptom in LDS type V, presents our multi-stage treatment and discusses the different therapeutic strategies.

Case studies in heritable vascular disease: Proceedings of the UTHealth Houston Multidisciplinary Aortic Conference

Heritable thoracic aortic disease is caused by dominantly inherited mutations in more than a dozen genes, including TGFB2 mutations that cause Loeys-Dietz syndrome. McGovern Medical School at UTHealth Houston convenes a regular conference that includes cardiothoracic and vascular surgeons, cardiologists, geneticists, radiologists, and pathologists to formulate multidisciplinary approaches for the management of complex heritable thoracic aortic disease cases. In this report, we highlight the unique management of individuals with distinct presentations of Loeys-Dietz syndrome owing to TGFB2 mutations.

A novel TGFBR2 mutation causes Loeys-Dietz syndrome in a Chinese infant: A case report

Introduction

Loeys-Dietz syndrome (LDS) is a rare autosomal dominant disorder with extensive connective tissue involvement. The diagnosis of this disease is mainly based on clinical features combined with the detection of pathogenic gene mutations, mainly mutations in the transforming growth factor-beta (TGF-β) signaling pathway.

Methods

The molecular pathogenesis of a LDS syndrome proband and his family members was analyzed using whole exome sequencing and validated using Sanger sequencing. Molecular dynamics simulations and in vitro cell experiments further analyzed the structural changes and functional abnormalities of the variation.

Results

This study describes the case of a 6-month-old infant diagnosed with LDS with typical craniofacial abnormalities, developmental delay, and a dilated aortic sinus (19 mm; Z-score 3.5). Genetic analysis showed the patient carried a novel de novo TGF-β receptor 2 (TGFBR2) mutation (NM_003242: c.1005_1007delGTA (p.Glu335_Tyr336delinsAsp)). Molecular dynamics simulation showed that the TGFBR2 c.1005_1007delGTA mutation changed the protein conformation, making the protein conformation more stable. The p.Glu335_Tyr336delinsAsp mutation significantly reduced TGF-β-induced gene transcription and phosphorylation of SMAD Family Member 2 (SMAD2) in vitro.

Conclusions

Our comprehensive genetic analysis suggested that the p.Glu335_Tyr336delinsAsp variant of TGFBR2 caused aberrant TGF-β signaling and contributed to LDS in the patient.

Aortic and arterial manifestations and clinical features in TGFB3-related heritable thoracic aortic disease: results from the Montalcino Aortic Consortium

BACKGROUND

Pathogenic variants in TGFB3 may lead to a syndromic genetic aortopathy. Heritable thoracic aortic disease (HTAD) and arterial events may occur in TGFB3-related disease but there are limited outcomes data on vascular events in this condition.

METHODS

Clinical data, phenotypical features and aortic outcomes in individuals with pathogenic/likely pathogenic (P/LP) TGFB3 variants enrolled in the Montalcino Aortic Consortium registry were reviewed.

RESULTS

34 individuals (56% male, median age 42 years, IQR 17-49, range 3-74 years) with P/LP TGFB3 variants were studied. Craniofacial, cutaneous and musculoskeletal features seen in Loeys-Dietz syndrome were variably present. Extra-aortic cardiovascular features included arterial tortuosity (25%), extra-aortic arterial aneurysms (6%) and mitral valve prolapse (21%).Aortic dilation (Z-Score>2) was present in 10 individuals (29%) and aortic dissection occurred in 2 (6%). Type A aortic dissection occurred in two patients (aged between 55 years and 60 years), and one of these patients experienced a type B aortic dissection 6 years later. Seven adults (median age 62 years, range 32-69 years) with aortic root dilation (41-49 mm) are being followed. No patients have undergone prophylactic aortic surgery. Twenty-five per cent of children have aortic dilation. Sixty-eight per cent of the entire cohort remains free of aortic disease. No deaths have occurred.

CONCLUSIONS

TGFB3-related HTAD is characterised by late-onset and less penetrant thoracic aortic and arterial disease compared with other transforming growth factor β HTAD. Based on our data, a larger aortic size threshold for prophylactic aortic surgery is appropriate in patients with TGFB3-related HTAD compared with HTAD due to TGFBR1 or TGFBR2 variants.

Immunotherapy resistance in solid tumors: mechanisms and potential solutions

While the emergence of immunotherapies has fundamentally altered the management of solid tumors, cancers exploit many complex biological mechanisms that result in resistance to these agents. These encompass a broad range of cellular activities - from modification of traditional paradigms of immunity via antigen presentation and immunoregulation to metabolic modifications and manipulation of the tumor microenvironment. Intervening on these intricate processes may provide clinical benefit in patients with solid tumors by overcoming resistance to immunotherapies, which is why it has become an area of tremendous research interest with practice-changing implications. This review details the major ways cancers avoid both natural immunity and immunotherapies through primary (innate) and secondary (acquired) mechanisms of resistance, and it considers available and emerging therapeutic approaches to overcoming immunotherapy resistance.

Intrinsic GATA4 expression sensitizes the aortic root to dilation in a Loeys-Dietz syndrome mouse model

Loeys-Dietz syndrome (LDS) is a connective tissue disorder caused by mutations that decrease transforming growth factor-β signaling. LDS-causing mutations increase the risk of aneurysm throughout the arterial tree, yet the aortic root is a site of heightened susceptibility. Here we investigate the heterogeneity of vascular smooth muscle cells (VSMCs) in the aorta of Tgfbr1M318R/+ LDS mice by single-cell transcriptomics to identify molecular determinants of this vulnerability. Reduced expression of components of the extracellular matrix-receptor apparatus and upregulation of stress and inflammatory pathways were observed in all LDS VSMCs. However, regardless of genotype, a subset of Gata4-expressing VSMCs predominantly located in the aortic root intrinsically displayed a less differentiated, proinflammatory profile. A similar population was also identified among aortic VSMCs in a human single-cell RNA sequencing dataset. Postnatal VSMC-specific Gata4 deletion reduced aortic root dilation in LDS mice, suggesting that this factor sensitizes the aortic root to the effects of impaired transforming growth factor-β signaling.

Genetic Problems, Diagnosis, and Cardiovascular Manifestations of Loeys-Dietz Syndrome

Loeys-Dietz Syndrome (LDS) is an autosomal dominant connective tissue disorder with multisystem involvement of wide spectrum, found to be associated with transforming growth factor-β pathway. LDS is characterized by craniofacial, skeletal, cutaneous, vascular abnormalities along with aortic aneurysm and aortic dissection contributing to mortality and morbidity at a young age. Therefore, timely diagnosis and intervention in patients with LDS is vital. Several gene mutations have been described as contributing factors of LDS, causing widespread and aggressive vascular disease. Based on these gene mutations, 5 types of LDS have been described so far. Besides aortic aneurysm and dissection, some of the other cardiac manifestations of LDS involve cardiomyopathy, valvular abnormality, atrial fibrillation, patent ductus arteriosus, atrial septal defects, etc. Routine imaging of patients' vasculatures and aggressive medical and surgical management are key factors in managing patients with LDS.

Elucidating the roles of SOD3 correlated genes and reactive oxygen species in rare human diseases using a bioinformatic-ontology approach

Superoxide Dismutase 3 (SOD3) scavenges extracellular superoxide giving a hydrogen peroxide metabolite. Both Reactive Oxygen Species diffuse through aquaporins causing oxidative stress and biomolecular damage. SOD3 is differentially expressed in cancer and this research utilises Gene Expression Omnibus data series GSE2109 with 2,158 cancer samples. Genome-wide expression correlation analysis was conducted with SOD3 as the seed gene. Categorical SOD3 Pearson Correlation gene lists incrementing in correlation strength by 0.01 from ρ≥|0.34| to ρ≥|0.41| were extracted from the data. Positively and negatively SOD3 correlated genes were separated for each list and checked for significance against disease overlapping genes in the ClinVar and Orphanet databases via Enrichr. Disease causal genes were added to the relevant gene list and checked against Gene Ontology, Phenotype Ontology, and Elsevier Pathways via Enrichr before the significant ontologies containing causal and non-overlapping genes were reviewed with a literature search for possible disease and oxidative stress associations. 12 significant individually discriminated disorders were identified: Autosomal Dominant Cutis Laxa (p = 6.05x10-7), Renal Tubular Dysgenesis of Genetic Origin (p = 6.05x10-7), Lethal Arteriopathy Syndrome due to Fibulin-4 Deficiency (p = 6.54x10-9), EMILIN-1-related Connective Tissue Disease (p = 6.54x10-9), Holt-Oram Syndrome (p = 7.72x10-10), Multisystemic Smooth Muscle Dysfunction Syndrome (p = 9.95x10-15), Distal Hereditary Motor Neuropathy type 2 (p = 4.48x10-7), Congenital Glaucoma (p = 5.24x210-9), Megacystis-Microcolon-Intestinal Hypoperistalsis Syndrome (p = 3.77x10-16), Classical-like Ehlers-Danlos Syndrome type 1 (p = 3.77x10-16), Retinoblastoma (p = 1.9x10-8), and Lynch Syndrome (p = 5.04x10-9). 35 novel (21 unique) genes across 12 disorders were identified: ADNP, AOC3, CDC42EP2, CHTOP, CNN1, DES, FOXF1, FXR1, HLTF, KCNMB1, MTF2, MYH11, PLN, PNPLA2, REST, SGCA, SORBS1, SYNPO2, TAGLN, WAPL, and ZMYM4. These genes are proffered as potential biomarkers or therapeutic targets for the corresponding rare diseases discussed.

Nrf-2/HO-1 activation protects against oxidative stress and inflammation induced by metal welding fume UFPs in 16HBE cells

As one of the main occupational hazards, welding fumes can cause oxidative damage and induce series of diseases, such as COPD or asthma. To clarify the effects of the metal fume ultrafine particulates (MF-UFPs) of welding fumes on oxidative damage, UFPs were collected by melt inert gas (MIG) and manual metal arc (MMA) welding, and the composition was confirmed. Human bronchial epithelial 16HBE cells were treated with 0-1000 µg/cm2 MF-UFPs to analyse the cytotoxicity, oxidative stress and cytokines. The protein and mRNA expression of Keap1-Nrf-2/antioxidant response elements (AREs) signalling pathway components were also analysed. After 4 h of treatment, the cell viability decreased 25% after 33.85 and 32.81 µg/cm2 MIG/MMA-UFPs treated. The intracellular ATP concentrations were also decreased significantly, while LDH leakage was increased. The decreased mitochondrial membrane potential and increased ROS suggested the occurrence of oxidative damage, and the results of proteome profiling arrays also showed a significant increase in IL-6 and IL-8. The expression of AREs which related to antioxidant and anti-inflammatory were also increased. These results indicate that the MF-UFPs can cause oxidative stress in 16HBE cells and activate the Nrf-2/ARE signalling pathway to against oxidative damage.

Targeted genetic analysis in a cohort of sporadic death from spontaneous rupture of thoracic aortic dissection in Han Chinese population

PURPOSE

Thoracic aortic dissection (TAD) is a life-threatening cardiovascular disease that often results in sudden cardiac death (SCD). However, the genetic characteristics of individuals with TAD confirmed at autopsy have been rarely studied. Our objective was to determine the prevalence of pathogenic variants in TAD-associated genes in a cohort of sporadic deaths resulting from spontaneous rupture of TAD and identify relevant genotype-phenotype relationships in Han Chinese population.

METHODS

We included sixty-one consecutive sporadic decedents whose primary cause of death was spontaneous rupture of TAD, and performed a whole exome sequencing based strategy comprising 26 known TAD-associated genes.

RESULTS

We identified 7 pathogenic or likely pathogenic (P/LP) variants in 7 cases (11.48 %) and 22 variants of uncertain significance (VUS) in 22 cases (36.07 %). The FBN1 gene was found to be the major disease-causing gene. Notably, TAD decedents with P/LP variant exhibited significantly earlier mortality. Moreover, we reported for the first time that TAD decedents with P/LP variant had a shorter diagnosis and treatment time.

CONCLUSION

Our study investigated the genetic characteristics of TAD individuals confirmed until autopsy in Han Chinese population. The findings enhanced the understanding of the genetic underpinnings of TAD and have significant implications for clinical management and forensic investigations.

Targeted next-generation sequencing reveals the genetic mechanism of Chinese Marfan syndrome cohort with ocular manifestation

BACKGROUND

Marfan syndrome (MFS) is a hereditary connective tissue disorder involving multiple systems, including ophthalmologic abnormalities. Most cases are due to heterozygous mutations in the fibrillin-1 gene (FBN1). Other associated genes include LTBP2, MYH11, MYLK, and SLC2A10. There is significant clinical overlap between MFS and other Marfan-like disorders.

PURPOSE

To expand the mutation spectrum of FBN1 gene and validate the pathogenicity of Marfan-related genes in patients with MFS and ocular manifestations.

METHODS

We recruited 318 participants (195 cases, 123 controls), including 59 sporadic cases and 88 families. All patients had comprehensive ophthalmic examinations showing ocular features of MFS and met Ghent criteria. Additionally, 754 cases with other eye diseases were recruited. Panel-based next-generation sequencing (NGS) screened mutations in 792 genes related to inherited eye diseases.

RESULTS

We detected 181 mutations with an 84.7% detection rate in sporadic cases and 87.5% in familial cases. The overall detection rate was 86.4%, with FBN1 accounting for 74.8%. In cases without FBN1 mutations, 23 mutations from seven Marfan-related genes were identified, including four pathogenic or likely pathogenic mutations in LTBP2. The 181 mutations included 165 missenses, 10 splicings, three frameshifts, and three nonsenses. FBN1 accounted for 53.0% of mutations. The most prevalent pathogenic mutation was FBN1 c.4096G>A. Additionally, 94 novel mutations were detected, with 13 de novo mutations in 14 families.

CONCLUSION

We expanded the mutation spectrum of the FBN1 gene and provided evidence for the pathogenicity of other Marfan-related genes. Variants in LTBP2 may contribute to the ocular manifestations in MFS, underscoring its role in phenotypic diversity.

Hereditary Aortic Aneurysms and Dissections: Clinical Diagnosis and Genetic Testing

Hereditary aortic aneurysms and dissections, such as Marfan syndrome, differ in that they occur in younger patients without generally recognized risk factors, have a predilection for the thoracic rather than the abdominal aorta, and are at risk for dissection even at smaller aortic diameters. Early diagnosis, careful follow-up, and early intervention, such as medication to reduce aortic root growth and prophylactic aortic replacement to prevent fatal aortic dissection, are essential for a better prognosis. Molecular genetic testing is extremely useful for early diagnosis. However, in actual clinical practice, the question often arises as to when and to which patient genetic testing should be offered since the outcome of the tests can have important implications for the patient and the relatives. Pre- and post-test genetic counseling is essential for early intervention to be effective. (This article is a secondary translation of Jpn J Vasc Surg 2023; 32: 261-267.).

Intrinsic Gata4 expression sensitizes the aortic root to dilation in a Loeys-Dietz syndrome mouse model

Loeys-Dietz syndrome (LDS) is an aneurysm disorder caused by mutations that decrease transforming growth factor-β (TGF-β) signaling. Although aneurysms develop throughout the arterial tree, the aortic root is a site of heightened risk. To identify molecular determinants of this vulnerability, we investigated the heterogeneity of vascular smooth muscle cells (VSMCs) in the aorta of Tgfbr1 M318R/+ LDS mice by single cell and spatial transcriptomics. Reduced expression of components of the extracellular matrix-receptor apparatus and upregulation of stress and inflammatory pathways were observed in all LDS VSMCs. However, regardless of genotype, a subset of Gata4-expressing VSMCs predominantly located in the aortic root intrinsically displayed a less differentiated, proinflammatory profile. A similar population was also identified among aortic VSMCs in a human scRNAseq dataset. Postnatal VSMC-specific Gata4 deletion reduced aortic root dilation in LDS mice, suggesting that this factor sensitizes the aortic root to the effects of impaired TGF-β signaling.

Genetic testing in cardiovascular disease

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality globally and is responsible for an estimated one-third of deaths as well as significant morbidity and health care utilisation. Technological and bioinformatic advances have facilitated the discovery of pathogenic germline variants for some specific CVDs, including familial hypercholesterolaemia, cardiomyopathies and arrhythmic syndromes. Use of these genetic tests for earlier disease identification is increasing due, in part, to decreasing costs, Medicare rebates, and consumer comfort with genetic testing. However, CVDs that occur more commonly, including coronary artery disease and atrial fibrillation, do not display monogenic inheritance patterns. Genetically, these diseases have generally been associated with many genetic variants each with a small effect size. This complexity can be expressed mathematically as a polygenic risk score. Genetic testing kits that provide polygenic risk scoring are becoming increasingly available directly to private-paying consumers outside the traditional clinical setting. An improved understanding of the evidence of genetics in CVD will offer clinicians new opportunities for individualised risk prediction and preventive therapy.

Advances and Challenges in Targeting TGF-β Isoforms for Therapeutic Intervention of Cancer: A Mechanism-Based Perspective

The TGF-β family is a group of 25 kDa secretory cytokines, in mammals consisting of three dimeric isoforms (TGF-βs 1, 2, and 3), each encoded on a separate gene with unique regulatory elements. Each isoform plays unique, diverse, and pivotal roles in cell growth, survival, immune response, and differentiation. However, many researchers in the TGF-β field often mistakenly assume a uniform functionality among all three isoforms. Although TGF-βs are essential for normal development and many cellular and physiological processes, their dysregulated expression contributes significantly to various diseases. Notably, they drive conditions like fibrosis and tumor metastasis/progression. To counter these pathologies, extensive efforts have been directed towards targeting TGF-βs, resulting in the development of a range of TGF-β inhibitors. Despite some clinical success, these agents have yet to reach their full potential in the treatment of cancers. A significant challenge rests in effectively targeting TGF-βs' pathological functions while preserving their physiological roles. Many existing approaches collectively target all three isoforms, failing to target just the specific deregulated ones. Additionally, most strategies tackle the entire TGF-β signaling pathway instead of focusing on disease-specific components or preferentially targeting tumors. This review gives a unique historical overview of the TGF-β field often missed in other reviews and provides a current landscape of TGF-β research, emphasizing isoform-specific functions and disease implications. The review then delves into ongoing therapeutic strategies in cancer, stressing the need for more tools that target specific isoforms and disease-related pathway components, advocating mechanism-based and refined approaches to enhance the effectiveness of TGF-β-targeted cancer therapies.

Diagnosis and treatment of cardiovascular disease in patients with heritable connective tissue disorders or heritable thoracic aortic diseases

Patients with heritable connective tissue disorders (HCTDs), represented by Marfan syndrome, can develop fatal aortic and/or arterial complications before age 50. Therefore, accurate diagnosis, appropriate medical treatment, and early prophylactic surgical treatment of aortic and arterial lesions are essential to improve prognosis. Patients with HCTDs generally present with specific physical features due to connective tissue abnormalities, while some patients with heritable thoracic aortic diseases (HTADs) have few distinctive physical characteristics. The development of genetic testing has made it possible to provide accurate diagnoses for patients with HCTDs/HTADs. This review provides an overview of the diagnosis and treatment of HCTDs/HTADs, including current evidence on cardiovascular interventions for this population.

Expanding the clinical spectrum of biglycan-related Meester-Loeys syndrome

Pathogenic loss-of-function variants in BGN, an X-linked gene encoding biglycan, are associated with Meester-Loeys syndrome (MRLS), a thoracic aortic aneurysm/dissection syndrome. Since the initial publication of five probands in 2017, we have considerably expanded our MRLS cohort to a total of 18 probands (16 males and 2 females). Segregation analyses identified 36 additional BGN variant-harboring family members (9 males and 27 females). The identified BGN variants were shown to lead to loss-of-function by cDNA and Western Blot analyses of skin fibroblasts or were strongly predicted to lead to loss-of-function based on the nature of the variant. No (likely) pathogenic missense variants without additional (predicted) splice effects were identified. Interestingly, a male proband with a deletion spanning the coding sequence of BGN and the 5' untranslated region of the downstream gene (ATP2B3) presented with a more severe skeletal phenotype. This may possibly be explained by expressional activation of the downstream ATPase ATP2B3 (normally repressed in skin fibroblasts) driven by the remnant BGN promotor. This study highlights that aneurysms and dissections in MRLS extend beyond the thoracic aorta, affecting the entire arterial tree, and cardiovascular symptoms may coincide with non-specific connective tissue features. Furthermore, the clinical presentation is more severe and penetrant in males compared to females. Extensive analysis at RNA, cDNA, and/or protein level is recommended to prove a loss-of-function effect before determining the pathogenicity of identified BGN missense and non-canonical splice variants. In conclusion, distinct mechanisms may underlie the wide phenotypic spectrum of MRLS patients carrying loss-of-function variants in BGN.

TGF-β signaling in health, disease, and therapeutics

Transforming growth factor (TGF)-β is a multifunctional cytokine expressed by almost every tissue and cell type. The signal transduction of TGF-β can stimulate diverse cellular responses and is particularly critical to embryonic development, wound healing, tissue homeostasis, and immune homeostasis in health. The dysfunction of TGF-β can play key roles in many diseases, and numerous targeted therapies have been developed to rectify its pathogenic activity. In the past decades, a large number of studies on TGF-β signaling have been carried out, covering a broad spectrum of topics in health, disease, and therapeutics. Thus, a comprehensive overview of TGF-β signaling is required for a general picture of the studies in this field. In this review, we retrace the research history of TGF-β and introduce the molecular mechanisms regarding its biosynthesis, activation, and signal transduction. We also provide deep insights into the functions of TGF-β signaling in physiological conditions as well as in pathological processes. TGF-β-targeting therapies which have brought fresh hope to the treatment of relevant diseases are highlighted. Through the summary of previous knowledge and recent updates, this review aims to provide a systematic understanding of TGF-β signaling and to attract more attention and interest to this research area.

Inducing aortic aneurysm/dissection in zebrafish: evaluating the efficacy of β-Aminopropionic Nitrile as a model

Aortic aneurysm/dissection (AAD) poses a life-threatening cardiovascular emergency with complex mechanisms and a notably high mortality rate. Zebrafish (Danio rerio) serve as valuable models for AAD due to the conservation of their three-layered arterial structure and genome with that of humans. However, the existing studies have predominantly focused on larval zebrafish, leaving a gap in our understanding of adult zebrafish. In this study, we utilized β-Aminopropionic Nitrile (BAPN) impregnation to induce AAD in both larval and adult zebrafish. Following induction, larval zebrafish exhibited a 28% widening of the dorsal aortic diameter (p < 0.0004, n = 10) and aortic arch malformations, with a high malformation rate of 75% (6/8). Conversely, adult zebrafish showed a 41.67% (5/12) mortality rate 22 days post-induction. At this time point, the dorsal aortic area had expanded by 2.46 times (p < 0.009), and the vessel wall demonstrated significant thickening (8.22 ± 2.23 μM vs. 26.38 ± 10.74 μM, p < 0.05). Pathological analysis revealed disruptions in the smooth muscle layer, contributing to a 58.33% aneurysm rate. Moreover, the expression levels of acta2, tagln, cnn1a, and cnn1b were decreased, indicating a weakened contractile phenotype. Transcriptome sequencing showed a significant overlap between the molecular features of zebrafish tissues post-BAPN treatment and those of AAD patients. Our findings present a straightforward and practical method for generating AAD models in both larval and adult zebrafish using BAPN.

Pectus excavatum and carinatum: a narrative review of epidemiology, etiopathogenesis, clinical features, and classification

Background and Objective

A wide variety of congenital chest wall deformities that manifest in infants, children and adolescents exists, among which are pectus excavatum and pectus carinatum. Numerous studies have been conducted over the years aiming to better understand these deformities. This report provides a brief overview of what is currently known about the epidemiology, etiopathogenesis, clinical presentation, and classification of these deformities, and highlights the gaps in knowledge.

Methods

A search was conducted for all the above-described domains in the PubMed and Embase databases.

Key Content and Findings

A total of 147 articles were included in this narrative review. Estimation of the true incidence and prevalence of pectus excavatum and carinatum is challenging due to lacking consensus on a definition of both deformities. Nowadays, several theories for the development of pectus excavatum and carinatum have been suggested which focus on intrinsic or extrinsic pathogenic factors, with the leading hypothesis focusing on overgrowth or growth disturbance of costal cartilages. Furthermore, genetic predisposition to the deformities is likely to exist. Pectus excavatum is frequently associated with cardiopulmonary symptoms, while pectus carinatum patients mostly present with cosmetic complaints. Both deformities are classified based on the shape or severity of the deformity. However, each classification system has its limitations.

Conclusions

Substantial progress has been made in the past few decades in understanding the development and symptomatology of pectus excavatum and carinatum. Current hypotheses on the etiology of the deformities should be confirmed by biomedical and genetic studies. For clinical purposes, the establishment of a clear definition and classification system for both deformities based on objective morphologic features is eagerly anticipated.

Severity of Autism Spectrum Disorder Symptoms Associated with de novo Variants and Pregnancy-Induced Hypertension

Genetic factors, particularly, de novo variants (DNV), and an environment factor, exposure to pregnancy-induced hypertension (PIH), were reported to be associated with risk of autism spectrum disorder (ASD); however, how they jointly affect the severity of ASD symptom is unclear. We assessed the severity of core ASD symptoms affected by functional de novo variants or PIH. We selected phenotype data from Simon's Simplex Collection database, used genotypes from previous studies, and created linear regression models. We found that ASD patients carrying DNV with PIH exposure had increased adaptive and cognitive ability, decreased social problems, and enhanced repetitive behaviors; however, there was no difference in patients without DNV between those with or without PIH exposure. In addition, the DNV genes carried by patients exposed to PIH were enriched in ubiquitin-dependent proteolytic processes, highlighting how candidate genes in pathways and environments interact. The results indicate the joint contribution of DNV and PIH to ASD.

The roles and regulatory mechanisms of TGF-β and BMP signaling in bone and cartilage development, homeostasis and disease

Transforming growth factor-βs (TGF-βs) and bone morphometric proteins (BMPs) belong to the TGF-β superfamily and perform essential functions during osteoblast and chondrocyte lineage commitment and differentiation, skeletal development, and homeostasis. TGF-βs and BMPs transduce signals through SMAD-dependent and -independent pathways; specifically, they recruit different receptor heterotetramers and R-Smad complexes, resulting in unique biological readouts. BMPs promote osteogenesis, osteoclastogenesis, and chondrogenesis at all differentiation stages, while TGF-βs play different roles in a stage-dependent manner. BMPs and TGF-β have opposite functions in articular cartilage homeostasis. Moreover, TGF-β has a specific role in maintaining the osteocyte network. The precise activation of BMP and TGF-β signaling requires regulatory machinery at multiple levels, including latency control in the matrix, extracellular antagonists, ubiquitination and phosphorylation in the cytoplasm, nucleus-cytoplasm transportation, and transcriptional co-regulation in the nuclei. This review weaves the background information with the latest advances in the signaling facilitated by TGF-βs and BMPs, and the advanced understanding of their diverse physiological functions and regulations. This review also summarizes the human diseases and mouse models associated with disordered TGF-β and BMP signaling. A more precise understanding of the BMP and TGF-β signaling could facilitate the development of bona fide clinical applications in treating bone and cartilage disorders.

Using Genomics to Identify Novel Therapeutic Targets for Aortic Disease

Aortic disease, including dissection, aneurysm, and rupture, carries significant morbidity and mortality and is a notable cause of sudden cardiac death. Much of our knowledge regarding the genetic basis of aortic disease has relied on the study of individuals with Mendelian aortopathies and, until recently, the genetic determinants of population-level variance in aortic phenotypes remained unclear. However, the application of machine learning methodologies to large imaging datasets has enabled researchers to rapidly define aortic traits and mine dozens of novel genetic associations for phenotypes such as aortic diameter and distensibility. In this review, we highlight the emerging potential of genomics for identifying causal genes and candidate drug targets for aortic disease. We describe how deep learning technologies have accelerated the pace of genetic discovery in this field. We then provide a blueprint for translating genetic associations to biological insights, reviewing techniques for locus and cell type prioritization, high-throughput functional screening, and disease modeling using cellular and animal models of aortic disease.

Current understanding of the genetics of thoracic aortic disease

Thoracic aortic dissection is a feared, highly lethal condition most commonly developing from aneurysmal dilation of the thoracic aorta. Elective prophylactic replacement of thoracic aortic aneurysms dramatically mitigates this risk. However, diagnosis of a thoracic aortic aneurysm can be challenging. Thoracic aortic disease - horacic aortic aneurysm and dissection (TAAD) - can be sporadic or heritable. Patients with syndromic heritable TAAD present with classic phenotype and clinical features correlating to their disease. In contrast, patients with non-syndromic heritable disease are harder to diagnose due to their lack of defining uniform phenotypes. Recent advances in genomics have begun to elucidate the genetic underpinnings of non-syndromic TAAD (ns-TAAD) for better understanding this complex disease and improve diagnosis and management. Herein, we review the foundation of knowledge in ns-TAAD heritability and key research studies identifying gene mutations in vascular smooth muscle cells, the extracellular matrix, and TGF-beta signaling present in ns-TAAD. We summarize the current guidelines for the diagnosis, screening, and surgical management of ns-TAAD including recommendations for genetic testing of high-risk individuals. Finally, we highlight areas of future research that will continue to advance our understanding of the complex genetic and epigenetic factors in TAAD.

Animal Models, Pathogenesis, and Potential Treatment of Thoracic Aortic Aneurysm

Thoracic aortic aneurysm (TAA) has a prevalence of 0.16-0.34% and an incidence of 7.6 per 100,000 person-years, accounting for 1-2% of all deaths in Western countries. Currently, no effective pharmacological therapies have been identified to slow TAA development and prevent TAA rupture. Large TAAs are treated with open surgical repair and less invasive thoracic endovascular aortic repair, both of which have high perioperative mortality risk. Therefore, there is an urgent medical need to identify the cellular and molecular mechanisms underlying TAA development and rupture to develop new therapies. In this review, we summarize animal TAA models including recent developments in porcine and zebrafish models: porcine models can assess new therapeutic devices or intervention strategies in a large mammal and zebrafish models can employ large-scale small-molecule suppressor screening in microwells. The second part of the review covers current views of TAA pathogenesis, derived from recent studies using these animal models, with a focus on the roles of the transforming growth factor-beta (TGFβ) pathway and the vascular smooth muscle cell (VSMC)-elastin-contractile unit. The last part discusses TAA treatment options as they emerge from recent preclinical studies.

Human Genetics of Semilunar Valve and Aortic Arch Anomalies

Lesions of the semilunar valve and the aortic arch can occur either in isolation or as part of well-described clinical syndromes. The polygenic cause of calcific aortic valve disease will be discussed including the key role of NOTCH1 mutations. In addition, the complex trait of bicuspid aortic valve disease will be outlined, both in sporadic/familial cases and in the context of associated syndromes, such as Alagille, Williams, and Kabuki syndromes. Aortic arch abnormalities particularly coarctation of the aorta and interrupted aortic arch, including their association with syndromes such as Turner and 22q11 deletion, respectively, are also discussed. Finally, the genetic basis of congenital pulmonary valve stenosis is summarized, with particular note to Ras-/mitogen-activated protein kinase (Ras/MAPK) pathway syndromes and other less common associations, such as Holt-Oram syndrome.

Genetic architecture of thoracic aortic dissection in the female population

BACKGROUND

Sex-related differences in cardiovascular disease are now gaining much more attention and their importance is increasingly being recognized, but little is known about the genetic distribution, genotype-phenotype correlation, and outcomes in the female population with thoracic aortic dissection (TAD).

METHODS

One hundred seventy-nine Chinese female probands with TAD were enrolled from Tongji Hospital between October 2009 and October 2020. Genetic analysis was performed among 12 genes, and participants were subsequently followed up for a median of 38.2 months for TAD-related death.

RESULTS

We identified 18 pathogenic or likely pathogenic variants among 18 (10.1%) probands and 21 variants of uncertain significance in 21 (11.7%) patients. Individuals with positive variants presented with a significant risk of TAD (OR: 12.0, 95% CI: 5.87-26.8), and an association between FBN1 (p = 2.60E-11, OR = 19.8), MYLK (p = 0.006, OR = 14.0) variants and an increased risk for female TAD was identified as well. Furthermore, nearly half of the variants were found in the FBN1 gene, which was significantly linked to early aortic dissection and tended to cause death at a young age.

CONCLUSION

This study revealed the monogenic contribution of known TAD genes to the female TAD population with East Asian ancestry. Patients who tested positive for FBN1 were significantly younger at the time of aortic dissection and had a higher probability of dying at an early age.

Degenerative mitral regurgitation

Degenerative mitral regurgitation is a major threat to public health and affects at least 24 million people worldwide, with an estimated 0.88 million disability-adjusted life years and 34,000 deaths in 2019. Improving access to diagnostic testing and to timely curative therapies such as surgical mitral valve repair will improve the outcomes of many individuals. Imaging such as echocardiography and cardiac magnetic resonance allow accurate diagnosis and have provided new insights for a better definition of the most appropriate timing for intervention. Advances in surgical techniques allow minimally invasive treatment with durable results that last for ≥20 years. Transcatheter therapies can provide good results in select patients who are considered high risk for surgery and have a suitable anatomy; the durability of such repairs is up to 5 years. Translational science has provided new knowledge on the pathophysiology of degenerative mitral regurgitation and may pave the road to the development of medical therapies that could be used to halt the progression of the disease.

Hippo Signaling Mediates TGFβ-Dependent Transcriptional Inputs in Cardiac Cushion Mesenchymal Cells to Regulate Extracellular Matrix Remodeling

The transforming growth factor beta (TGFβ) and Hippo signaling pathways are evolutionarily conserved pathways that play a critical role in cardiac fibroblasts during embryonic development, tissue repair, and fibrosis. TGFβ signaling and Hippo signaling are also important for cardiac cushion remodeling and septation during embryonic development. Loss of TGFβ2 in mice causes cardiac cushion remodeling defects resulting in congenital heart disease. In this study, we used in vitro molecular and pharmacologic approaches in the cushion mesenchymal cell line (tsA58-AVM) and investigated if the Hippo pathway acts as a mediator of TGFβ2 signaling. Immunofluorescence staining showed that TGFβ2 induced nuclear translocation of activated SMAD3 in the cushion mesenchymal cells. In addition, the results indicate increased nuclear localization of Yes-associated protein 1 (YAP1) following a similar treatment of TGFβ2. In collagen lattice formation assays, the TGFβ2 treatment of cushion cells resulted in an enhanced collagen contraction compared to the untreated cushion cells. Interestingly, verteporfin, a YAP1 inhibitor, significantly blocked the ability of cushion cells to contract collagen gel in the absence or presence of exogenously added TGFβ2. To confirm the molecular mechanisms of the verteporfin-induced inhibition of TGFβ2-dependent extracellular matrix (ECM) reorganization, we performed a gene expression analysis of key mesenchymal genes involved in ECM remodeling in heart development and disease. Our results confirm that verteporfin significantly decreased the expression of α-smooth muscle actin (Acta2), collagen 1a1 (Col1a1), Ccn1 (i.e., Cyr61), and Ccn2 (i.e., Ctgf). Western blot analysis indicated that verteporfin treatment significantly blocked the TGFβ2-induced activation of SMAD2/3 in cushion mesenchymal cells. Collectively, these results indicate that TGFβ2 regulation of cushion mesenchymal cell behavior and ECM remodeling is mediated by YAP1. Thus, the TGFβ2 and Hippo pathway integration represents an important step in understanding the etiology of congenital heart disease.

Aortic aneurysms: current pathogenesis and therapeutic targets

Aortic aneurysm is a chronic disease characterized by localized expansion of the aorta, including the ascending aorta, arch, descending aorta, and abdominal aorta. Although aortic aneurysms are generally asymptomatic, they can threaten human health by sudden death due to aortic rupture. Aortic aneurysms are estimated to lead to 150,000 ~ 200,000 deaths per year worldwide. Currently, there are no effective drugs to prevent the growth or rupture of aortic aneurysms; surgical repair or endovascular repair is the only option for treating this condition. The pathogenic mechanisms and therapeutic targets for aortic aneurysms have been examined over the past decade; however, there are unknown pathogenic mechanisms involved in cellular heterogeneity and plasticity, the complexity of the transforming growth factor-β signaling pathway, inflammation, cell death, intramural neovascularization, and intercellular communication. This review summarizes the latest research findings and current pathogenic mechanisms of aortic aneurysms, which may enhance our understanding of aortic aneurysms.

2022 ACC/AHA guideline for the diagnosis and management of aortic disease: A report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines

AIM

The "2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease" provides recommendations to guide clinicians in the diagnosis, genetic evaluation and family screening, medical therapy, endovascular and surgical treatment, and long-term surveillance of patients with aortic disease across its multiple clinical presentation subsets (ie, asymptomatic, stable symptomatic, and acute aortic syndromes).

METHODS

A comprehensive literature search was conducted from January 2021 to April 2021, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, CINHL Complete, and other selected databases relevant to this guideline. Additional relevant studies, published through June 2022 during the guideline writing process, were also considered by the writing committee, where appropriate.

STRUCTURE

Recommendations from previously published AHA/ACC guidelines on thoracic aortic disease, peripheral artery disease, and bicuspid aortic valve disease have been updated with new evidence to guide clinicians. In addition, new recommendations addressing comprehensive care for patients with aortic disease have been developed. There is added emphasis on the role of shared decision making, especially in the management of patients with aortic disease both before and during pregnancy. The is also an increased emphasis on the importance of institutional interventional volume and multidisciplinary aortic team expertise in the care of patients with aortic disease.

Early clinical outcomes and molecular smooth muscle cell phenotyping using a prophylactic aortic arch replacement strategy in Loeys-Dietz syndrome

OBJECTIVES

Patients with Loeys-Dietz syndrome demonstrate a heightened risk of distal thoracic aortic events after valve-sparing aortic root replacement. This study assesses the clinical risks and hemodynamic consequences of a prophylactic aortic arch replacement strategy in Loeys-Dietz syndrome and characterizes smooth muscle cell phenotype in Loeys-Dietz syndrome aneurysmal and normal-sized downstream aorta.

METHODS

Patients with genetically confirmed Loeys-Dietz syndrome (n = 8) underwent prophylactic aortic arch replacement during valve-sparing aortic root replacement. Four-dimensional flow magnetic resonance imaging studies were performed in 4 patients with Loeys-Dietz syndrome (valve-sparing aortic root replacement + arch) and compared with patients with contemporary Marfan syndrome (valve-sparing aortic root replacement only, n = 5) and control patients (without aortopathy, n = 5). Aortic tissues from 4 patients with Loeys-Dietz syndrome and 2 organ donors were processed for anatomically segmented single-cell RNA sequencing and histologic assessment.

RESULTS

Patients with Loeys-Dietz syndrome valve-sparing aortic root replacement + arch had no deaths, major morbidity, or aortic events in a median of 2 years follow-up. Four-dimensional magnetic resonance imaging demonstrated altered flow parameters in patients with postoperative aortopathy relative to controls, but no clear deleterious changes due to arch replacement. Integrated analysis of aortic single-cell RNA sequencing data (>49,000 cells) identified a continuum of abnormal smooth muscle cell phenotypic modulation in Loeys-Dietz syndrome defined by reduced contractility and enriched extracellular matrix synthesis, adhesion receptors, and transforming growth factor-beta signaling. These modulated smooth muscle cells populated the Loeys-Dietz syndrome tunica media with gradually reduced density from the overtly aneurysmal root to the nondilated arch.

CONCLUSIONS

Patients with Loeys-Dietz syndrome demonstrated excellent surgical outcomes without overt downstream flow or shear stress disturbances after concomitant valve-sparing aortic root replacement + arch operations. Abnormal smooth muscle cell-mediated aortic remodeling occurs within the normal diameter, clinically at-risk Loeys-Dietz syndrome arch segment. These initial clinical and pathophysiologic findings support concomitant arch replacement in Loeys-Dietz syndrome.

Unraveling the role of TGFβ signaling in thoracic aortic aneurysm and dissection using Fbn1 mutant mouse models

Although abnormal TGFβ signaling is observed in several heritable forms of thoracic aortic aneurysms and dissections including Marfan syndrome, its precise role in aortic disease progression is still disputed. Using a mouse genetic approach and quantitative isobaric labeling proteomics, we sought to elucidate the role of TGFβ signaling in three Fbn1 mutant mouse models representing a range of aortic disease from microdissection (without aneurysm) to aneurysm (without rupture) to aneurysm and rupture. Results indicated that reduced TGFβ signaling and increased mast cell proteases were associated with microdissection. In contrast, increased abundance of extracellular matrix proteins, which could be reporters for positive TGFβ signaling, were associated with aneurysm. Marked reductions in collagens and fibrillins, and increased TGFβ signaling, were associated with aortic rupture. Our data indicate that TGFβ signaling performs context-dependent roles in the pathogenesis of thoracic aortic disease.

Vertebral Tortuosity Is Associated With Increased Rate of Cardiovascular Events in Vascular Ehlers-Danlos Syndrome

Background Arterial tortuosity is associated with adverse events in Marfan and Loeys-Dietz syndromes but remains understudied in Vascular Ehlers-Danlos syndrome. Methods and Results Subjects with a pathogenic COL3A1 variant diagnosed at age <50 years were included from 2 institutions and the GenTAC Registry (National Registry of Genetically Triggered Thoracic Aortic Aneurysms and Cardiovascular Conditions). Height-adjusted vertebral artery tortuosity index (VTI-h) using magnetic resonance or computed tomography angiography was calculated. Associations between VTI-h and outcomes of (1) cardiovascular events (arterial dissection/rupture, aneurysm requiring intervention, stroke), or (2) hollow organ collapse/rupture at age <50 years were evaluated using receiver operator curve analysis (using outcome by age 30 years) and mixed-effects Poisson regression for incidence rate ratios. Of 65 subjects (54% male), median VTI-h was 12 (interquartile range, 8-16). Variants were missense in 46%, splice site in 31%, and null/gene deletion in 14%. Thirty-two subjects (49%) had 59 events, including 28 dissections, 5 arterial ruptures, 4 aneurysms requiring intervention, 4 strokes, 11 hollow organ ruptures, and 7 pneumothoraces. Receiver operator curve analysis suggested optimal discrimination at VTI-h ≥15.5 for cardiovascular events (sensitivity 70%, specificity 76%) and no association with noncardiovascular events (area under the curve, 0.49 [95% CI, 0.22-0.78]). By multivariable analysis, older age was associated with increased cardiovascular event rate while VTI-h ≥15.5 was not (incidence rate ratios, 1.79 [95% CI, 0.76-4.24], P=0.185). However, VTI-h ≥15.5 was associated with events among those with high-risk variants <40 years (incidence rate ratios, 4.14 [95% CI, 1.13-15.10], P=0.032), suggesting effect modification by genotype and age. Conclusions Increased arterial tortuosity is associated with a higher incidence rate of cardiovascular events in Vascular Ehlers-Danlos syndrome. Vertebral tortuosity index may be a useful biomarker for prognosis when evaluated in conjunction with genotype and age.

TGF-β signaling in health and disease

The TGF-β regulatory system plays crucial roles in the preservation of organismal integrity. TGF-β signaling controls metazoan embryo development, tissue homeostasis, and injury repair through coordinated effects on cell proliferation, phenotypic plasticity, migration, metabolic adaptation, and immune surveillance of multiple cell types in shared ecosystems. Defects of TGF-β signaling, particularly in epithelial cells, tissue fibroblasts, and immune cells, disrupt immune tolerance, promote inflammation, underlie the pathogenesis of fibrosis and cancer, and contribute to the resistance of these diseases to treatment. Here, we review how TGF-β coordinates multicellular response programs in health and disease and how this knowledge can be leveraged to develop treatments for diseases of the TGF-β system.

Extracellular Matrix Remodeling in Vascular Disease: Defining Its Regulators and Pathological Influence

Because of structural and cellular differences (ie, degrees of matrix abundance and cross-linking, mural cell density, and adventitia), large and medium-sized vessels, in comparison to capillaries, react in a unique manner to stimuli that induce vascular disease. A stereotypical vascular injury response is ECM (extracellular matrix) remodeling that occurs particularly in larger vessels in response to injurious stimuli, such as elevated angiotensin II, hyperlipidemia, hyperglycemia, genetic deficiencies, inflammatory cell infiltration, or exposure to proinflammatory mediators. Even with substantial and prolonged vascular damage, large- and medium-sized arteries, persist, but become modified by (1) changes in vascular wall cellularity; (2) modifications in the differentiation status of endothelial cells, vascular smooth muscle cells, or adventitial stem cells (each can become activated); (3) infiltration of the vascular wall by various leukocyte types; (4) increased exposure to critical growth factors and proinflammatory mediators; and (5) marked changes in the vascular ECM, that remodels from a homeostatic, prodifferentiation ECM environment to matrices that instead promote tissue reparative responses. This latter ECM presents previously hidden matricryptic sites that bind integrins to signal vascular cells and infiltrating leukocytes (in coordination with other mediators) to proliferate, invade, secrete ECM-degrading proteinases, and deposit injury-induced matrices (predisposing to vessel wall fibrosis). In contrast, in response to similar stimuli, capillaries can undergo regression responses (rarefaction). In summary, we have described the molecular events controlling ECM remodeling in major vascular diseases as well as the differential responses of arteries versus capillaries to key mediators inducing vascular injury.

Variable clinical expression of a Belgian TGFB3 founder variant suggests the presence of a genetic modifier

Background: TGFB3 variants cause Loeys-Dietz syndrome type 5, a syndromic form of thoracic aortic aneurysm and dissection. The exact disease phenotype is hard to delineate because of few identified cases and highly variable clinical representation. Methodology: We provide the results of a haplotype analysis and a medical record review of clinical features of 27 individuals from 5 different families, originating from the Campine region in Flanders, carrying the NM_003239.5(TGFB3):c.787G>C p.(Asp263His) likely pathogenic variant, dbSNP:rs796051886, ClinVar:203492. The Asp263 residue is essential for integrin binding to the Arg-Gly-Asp (RGD) motif of the TGFβ3-cytokine. Results: The haplotype analysis revealed a shared haplotype of minimum 1.92 Mb and maximum 4.14 Mb, suggesting a common founder originating >400 years ago. Variable clinical features included connective tissue manifestations, non-aneurysmal cardiovascular problems such as hypertrophic cardiomyopathy, bicuspid aortic valve, mitral valve disease, and septal defects. Remarkably, only in 4 out of the 27 variant-harboring individuals, significant aortic involvement was observed. In one family, a 31-year-old male presented with type A dissection. In another family, the male proband (65 years) underwent a Bentall procedure because of bicuspid aortic valve insufficiency combined with sinus of Valsalva of 50 mm, while an 80-year-old male relative had an aortic diameter of 43 mm. In a third family, the father of the proband (75 years) presented with ascending aortic aneurysm (44 mm). Conclusion: The low penetrance (15%) of aortic aneurysm/dissection suggests that haploinsufficiency alone by the TGFB3 variant may not result in aneurysm development but that additional factors are required to provoke the aneurysm phenotype.

TGFβ-2 haploinsufficiency causes early death in mice with Marfan syndrome

To assess the contribution of individual TGF-β isoforms to aortopathy in Marfan syndrome (MFS), we quantified the survival and phenotypes of mice with a combined fibrillin1 (the gene defective in MFS) hypomorphic mutation and a TGF-β1, 2, or 3 heterozygous null mutation. The loss of TGF-β2, and only TGF-β2, resulted in 80% of the double mutant animals dying earlier, by postnatal day 20, than MFS only mice. Death was not from thoracic aortic rupture, as observed in MFS mice, but was associated with hyperplastic aortic valve leaflets, aortic regurgitation, enlarged aortic root, increased heart weight, and impaired lung alveolar septation. Thus, there appears to be a relationship between loss of fibrillin1 and TGF-β2 in the postnatal development of the heart, aorta and lungs.