Genetics of bicuspid aortic valve aortopathy

miR-130a expression is related to aortic dilation in bicuspid aortic valve children

BACKGROUND

Bicuspid aortic valve disease (BAV) is present in 0.5-2% of the population and can promote aortic dilation, eventually leading to fatal consequences. Although some biomarkers have been proposed in adults, no studies have tested these candidates in children. We aimed to evaluate four miRNAs previously described to be related to BAV disease and aortic dilation in adults in a paediatric cohort.

METHODS

Eighty participants ≤17 years old (4-17; mean 12) were included. From the BAV group, 40% had a dilated aorta (z score >2). RT‒qPCR were performed in plasma samples to quantify miR-122, miR-130a, miR-486, and miR-718 using the delta-delta Ct method. Functional and enrichment analyses of miR-130a were also performed.

RESULTS

miR-130a expression in plasma was found to be significantly lower in BAV patients with a dilated aorta versus nondilated patients (p = 0.008) and healthy TAV controls (p = 0.004). Furthermore, miR-130a expression in plasma was inversely correlated with ascending aorta (r = 0.318, p = 0.004) and aortic root z scores (r = 0.322; p = 0.004). Enrichment analysis showed that miR-130a target genes are related to the TGFβ signalling pathway.

CONCLUSIONS

miR-130a expression in plasma is decreased in aortic-dilated BAV children compared to nondilated BAV children, helping differentiate low- to high-risk patients.

IMPACT

miR-130a expression in plasma is related to aortic dilation in bicuspid aortic valve (BAV) children. To our knowledge, this is the first study that analyses miRNA patterns in bicuspid aortic valve children with aortic dilation. miR-130a expression in plasma could be a biomarker in order to help differentiate low-to high-risk BAV children, which is vitally important for advanced care planning.

Transcatheter Aortic Valve Therapy for Bicuspid Aortic Valve Stenosis

Transcatheter aortic valve implantation (TAVI) has become first-line treatment for older adults with severe aortic stenosis (AS), however, patients with bicuspid aortic valve (BAV) have been traditionally excluded from randomised trials and guidelines. As familiarity and proficiency of TAVI operators have improved, case-series and observational data have demonstrated the feasibility of successful TAVI in bicuspid aortic valve aortic stenosis (BAV-AS), however, patients with BAV-AS have several distinct characteristics that influence the likelihood of TAVI success. This review aims to summarise the pathophysiology and classification of BAV, published safety data, anatomical challenges and procedural considerations essential for pre-procedural planning, patient selection and procedural success of TAVI in BAV.

Coarctation of the Aorta: Modern Paradigms Across the Lifespan

While coarctation of the aorta varies greatly in both severity and age at presentation, all patients are at increased risk of hypertension both before and after repair. Despite advances in knowledge about genetic etiologies, pathophysiologic mechanisms, and optimal repair strategies, patients with repaired coarctation of the aorta remain at increased risk of acquired cardiovascular disease. The aims of this review are to describe the management of coarctation of the aorta at all ages before and after repair, highlight pathophysiologic mechanisms of hypertension, and review long-term follow-up considerations.

Mechanisms of Aortic Dilation in Patients With Bicuspid Aortic Valve: JACC State-of-the-Art Review

Bicuspid aortic valve is the most common congenital heart disease and exposes patients to an increased risk of aortic dilation and dissection. Aortic dilation is a slow, silent process, leading to a greater risk of aortic dissection. The prevention of adverse events together with optimization of the frequency of the required lifelong imaging surveillance are important for both clinicians and patients and motivated extensive research to shed light on the physiopathologic processes involved in bicuspid aortic valve aortopathy. Two main research hypotheses have been consolidated in the last decade: one supports a genetic basis for the increased prevalence of dilation, in particular for the aortic root, and the second supports the damaging impact on the aortic wall of altered flow dynamics associated with these structurally abnormal valves, particularly significant in the ascending aorta. Current opinion tends to rule out mutually excluding causative mechanisms, recognizing both as important and potentially clinically relevant.

Bicuspid aortic valve with associated aortopathy, significant left ventricular hypertrophy or concomitant hypertrophic cardiomyopathy: A diagnostic and therapeutic challenge

Due to its prevalence of 0.5% to 2% in the general population, with a 75% predominance among men, bicuspid aortic valve is the most common congenital heart defect. It is frequently accompanied by other cardiac congenital anomalies, and clinical presentation can vary significantly, with stenosis being the most common manifestation, often resulting in mild to moderate concentric hypertrophy of the left ventricle. Echocardiography is the primary diagnostic modality utilized for establishing the diagnosis, and it is often the sole diagnostic tool relied upon by clinicians. However, due to the heterogeneous clinical presentation and possible associated anomalies (which are often overlooked in clinical practice), it is necessary to employ various diagnostic methods and persist in finding the accurate diagnosis if multiple inconsistencies exist. By employing this approach, we can effectively manage these patients and provide them with appropriate treatment. Through a clinical case from our practice, we provide an overview of the literature on bicuspid aortic valve with aortophaty and the possible association with hypertrophic cardiomyopathy, diagnostic methods, and treatment options. This review article highlights the critical significance of achieving an accurate diagnosis in patients with bicuspid aortic valve and significant left ventricular hypertrophy. It is crucial to exclude other possible causes of left ventricular outflow tract obstruction, such as sub- or supra-aortic obstructions, and hypertrophic cardiomyopathy.

Glycoprotein and Lipoprotein Profiles Assessed by 1H-NMR and Its Relation to Ascending Aortic Dilatation in Bicuspid Aortic Valve Disease

INTRODUCTION

The bicuspid aortic valve (BAV) confers a high risk of ascending aorta dilatation (AAoD), although its progression seems highly variable. Furthermore, the implication of lipoprotein metabolism and inflammation in the mechanisms that underlie AAoD is not fully established. The aim of this study consisted of evaluating the impact of the lipoprotein and glycoprotein profiles in AAOD as well as its progression in BAV aortopathy.

METHODS

Using 1H-nuclear magnetic resonance (1H-NMR), we analyzed and compared the lipoprotein and glycoprotein profiles of plasma samples from 152 BAV patients with dilated and nondilated ascending aorta. Additionally, these profiles were also compared for 119 of these patients who were prospectively followed-up clinically and by echocardiography in the long-term (5 years). Ascending aorta dilation velocity (mm/year) was calculated for this analysis.

RESULTS

Several parameters related to the lipoprotein profile including remnant cholesterol, small LDL and IDL-cholesterol were found to be significantly increased in the dilated group compared to those in the nondilated group. The glycoprotein A-nuclear magnetic resonance (NMR) signal, a novel inflammation biomarker, was also observed to be increased in the dilated group. After performing multivariate analysis, remnant cholesterol remained an independent variable related to AAoD. In the long-term follow-up, proatherogenic lipoprotein parameters were related to ascending aorta dilatation velocity ascending. After a lineal regression analysis, non-HDL particles remained as an independent predictor of ascending aorta dilation velocity.

CONCLUSIONS

Patients with BAV and AAoD presented a more pro-atherogenic profile assessed by 1H-NMR, especially related to triglyceride-rich lipoproteins. This pro-atherogenic profile seems to contribute to the higher growth rate of ascending aorta diameter.

Phenotypes of Cardiovascular Diseases: Current Status and Future Perspectives

Cardiovascular diseases (CVDs) are a large group of diseases and have become the leading cause of morbidity and mortality worldwide. Although considerable progresses have been made in the diagnosis, treatment and prognosis of CVD, communication barriers between clinicians and researchers still exist because the phenotypes of CVD are complex and diverse in clinical practice and lack of unity. Therefore, it is particularly important to establish a standardized and unified terminology to describe CVD. In recent years, there have been several studies, such as the Human Phenotype Ontology, attempting to provide a standardized description of the disease phenotypes. In the present article, we outline recent advances in the classification of the major types of CVD to retrospectively review the current progresses of phenotypic studies in the cardiovascular field and provide a reference for future cardiovascular research.

Aortic root aortopathy in bicuspid aortic valve associated with high genetic risk

Background

The bicuspid aortic valve (BAV) is prone to ascending aortic dilatation (AAD) involving both the tubular segment and the aortic root. The genetic factor was proposed as one of the most important mechanisms for AAD. We hypothesized that the rare genetic variants mainly contribute to the pathogenesis of aortic roots in affected individuals.

Methods

The diameter of aortic root or ascending aorta ≥ 40 mm was counted as AAD. The targeted next-generation sequencing of 13 BAV-associated genes were performed on a continuous cohort of 96 unrelated BAV patients. The rare variants with allele frequency < 0.05% were selected and analyzed. Variants frequency was compared against the Exome aggregation consortium database. The pathogenicity of the genetic variants was evaluated according to the American College of Medical Genetics and Genomics guidelines.

Results

A total of 27 rare nonsynonymous coding variants involving 9 genes were identified in 25 individuals. The burden analysis revealed that variants in GATA5, GATA6, and NOTCH1 were significantly associated with BAV. Eighty percent of the pathogenic variants were detected in root group. The detection rate of rare variants was higher in root dilatation group (71.4%) compared with normal aorta (29.0%) and tubular dilatation groups (29.6%) (P = 0.018). The rare variant was identified as the independent risk factor of root dilatation [P = 0.014, hazard ratio = 23.9, 95% confidence interval (1.9–302.9)].

Conclusions

Our results presented a broad genetic spectrum in BAV patients. The rare variants of BAV genes contribute the most to the root phenotype among BAV patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02215-y.

MicroRNAs involve in bicuspid aortic aneurysm: pathogenesis and biomarkers

The incidence of bicuspid aortic valves (BAV) is high in the whole population, BAV-related thoracic aortic aneurysm (TAA) is accompanied by many adverse vascular events. So far, there are two key points in dealing with BAV-related TAA. First is fully understanding on its pathogenesis. Second is optimizing surgical intervention time. This review aims to illustrate the potential role of miRNAs in both aspects, that is, how miRNAs are involved in the occurrence and progression of BAV-related TAA, and the feasibilities of miRNAs as biomarkers.

Extent of Coronary Artery Disease in Patients With Stenotic Bicuspid Versus Tricuspid Aortic Valves

Background Bicuspid aortic valve (BAV) is the most common congenital cardiac malformation, which is often complicated by aortic valve stenosis (AoS). In tricuspid aortic valve (TAV), AoS strongly associates with coronary artery disease (CAD) with common pathophysiological factors. Yet, it remains unclear whether AoS in patients with BAV is also associated with CAD. This study investigated the association between the aortic valve morphological features and the extent of CAD. Methods and Results A single-center study was performed, including all patients who underwent an aortic valve replacement attributable to AoS between 2006 and 2019. Coronary sclerosis was graded on preoperative coronary angiographies using the coronary artery greater even than scoring method, which divides the coronaries in 28 segments and scores nonobstructive (20%-49% sclerosis) and obstructive coronary sclerosis (>49% sclerosis) in each segment. Multivariate analyses were performed, controlling for age, sex, and CAD risk factors. A total of 1296 patients (931 TAV and 365 BAV) were included, resulting in 548 matched patients. Patients with TAV exhibited more CAD risk factors (odds ratio [OR], 2.66; 95% CI, 1.79-3.96; P<0.001). Patients with BAV had lower coronary artery greater even than 20 (1.61±2.35 versus 3.60±2.79) and coronary artery greater even than 50 (1.24±2.43 versus 3.37±3.49) scores (P<0.001), even after correcting for CAD risk factors (P<0.001). Patients with TAV more often needed concomitant coronary revascularization (OR, 3.50; 95% CI, 2.42-5.06; P<0.001). Conclusions Patients with BAV who are undergoing surgery for AoS carry a lower cardiovascular risk profile, correlating with less coronary sclerosis and a lower incidence of concomitant coronary revascularization compared with patients with TAV.

Assessing the methodology used to study the ascending aorta haemodynamics in bicuspid aortic valve

Aims

Modern imaging techniques provide evermore-detailed anatomical and physiological information for use in computational fluid dynamics to predict the behaviour of physiological phenomena. Computer modelling can help plan suitable interventions. Our group used magnetic resonance imaging and computational fluid dynamics to study the haemodynamic variables in the ascending aorta in patients with bicuspid aortic valve before and after isolated tissue aortic valve replacement. Computer modelling requires turning a physiological model into a mathematical one, solvable by equations that undergo multiple iterations in four dimensions. Creating these models involves several steps with manual inputs, making the process prone to errors and limiting its inter- and intra-operator reproducibility. Despite these challenges, we created computational models for each patient to study ascending aorta blood flow before and after surgery.

Methods and results

Magnetic resonance imaging provided the anatomical and velocity data required for the blood flow simulation. Patient-specific in- and outflow boundary conditions were used for the computational fluid dynamics analysis. Haemodynamic variables pertaining to blood flow pattern and derived from the magnetic resonance imaging data were calculated. However, we encountered problems in our multi-step methodology, most notably processing the flow data. This meant that other variables requiring computation with computational fluid dynamics could not be calculated.

Conclusion

Creating a model for computational fluid dynamics analysis is as complex as the physiology under scrutiny. We discuss some of the difficulties associated with creating such models, along with suggestions for improvements in order to yield reliable and beneficial results.

Update in Biomolecular and Genetic Bases of Bicuspid Aortopathy

Bicuspid aortic valve (BAV) associated with aortopathy is the most common congenital heart disease in the general population. Far from being a simple harmless valve malformation, it can be a complex and heterogeneous disease and a source of chronic and acute pathology (early valvular disease, aneurysm, dissection). In the previous years, intense research has been carried out to find out and understand its mechanisms, but the pathophysiology of the disease is still not fully understood and many questions remain open. Recent studies have discovered several genetic mutations involved in the development of valvular and aortic malformations, but still cannot explain more than 5–10% of cases. Other studies have also focused on molecular alterations and cellular processes (TGF-β pathway, microRNAs, degradation of the extracellular matrix, metalloproteinases, etc.), being a field in constant search and development, looking for a therapeutic target to prevent the development of the disease. Increased knowledge about this multifaceted disorder, derived from both basic and clinical research, may influence the diagnosis, follow-up, prognosis, and therapies of affected patients in the near future. This review focuses on the latest and outstanding developments on the molecular and genetic investigations of the bicuspid aortopathy.

Relationship between indexed aortic area and aortic diameter in bicuspid aortic valve aortopathy: A retrospective cohort study

BACKGROUND

Aortic dissection is a life-threatening complication of bicuspid aortic valve (BAV)-associated aortopathy. In these populations, whilst prophylactic replacement of proximal thoracic aortic aneurysms (TAAs) is generally recommended at threshold diameters ≥5.5 cm, dissection may occur in smaller aortas. An alternative size-based parameter, the cross-sectional aortic area/patient height ratio (indexed aortic area, IAA), correlates with increased dissection risk at abnormal values > 10 cm2/m. We sought to assess the utility of the IAA in identifying at-risk BAV-associated TAAs with abnormal IAA, albeit with sub-threshold aortic diameter.

MATERIALS AND METHODS

We retrospectively identified 69 patients with BAV-associated TAAs who underwent surgical repair between 2010 and 2016. Aortic diameter was measured on pre-operative imaging, and IAA calculated, at the mid-sinus of Valsalva, sino-tubular junction and mid-ascending aorta for each patient. We determined proportions of aneurysms with IAA >10 cm2/m, median IAAs corresponding to aortic diameters <4.0 cm, 4.0-4.5 cm, 4.5-5.0 cm, 5.0-5.5 cm and >5.5 cm, and median aortic diameters corresponding to an abnormal IAA.

RESULTS

50.9%, 12.5% and 64.6% of aneurysms at the sinus of Valsalva, sino-tubular junction and mid-ascending aorta, respectively, had an abnormal IAA. 51.9% and 88.9% of patients with aortic diameter 4.5-5.0 cm and 5.0-5.5 cm, respectively, had an abnormal IAA. In aneurysms with abnormal IAA involving the sinus of Valsalva, sino-tubular junction, and mid-ascending aorta, median aortic diameters were 4.98 cm, 5.04 cm and 5.11 cm, respectively. Overall, 57/72 (79.2%) at-risk aneurysms with IAA >10 cm2/m had diameters smaller than the 5.5 cm guideline cut-off for surgical intervention.

CONCLUSION

Significant proportions of BAV-associated TAAs are at increased risk of aortic dissection attending an IAA >10 cm2/m, whilst not fulfilling the size criteria indicating aortic surgery in contemporary guidelines. Further analysis of IAA in larger BAV cohorts is necessary to clarify its role in patient selection and optimal timing for prophylactic aortic replacement.

Prevalence of Bicuspid Aortic Valve and Associated Aortopathy in Newborns in Copenhagen, Denmark

IMPORTANCE

The prevalence and characteristics of bicuspid aortic valve (BAV) are mainly reported from selected cohorts. BAV is associated with aortopathy, but it is unclear if it represents a fetal developmental defect or is secondary to abnormal valve dynamics.

OBJECTIVE

To determine the prevalence of BAV and BAV subtypes and to describe the associated aortopathy in a large, population-based cohort of newborns.

DESIGN, SETTING, AND PARTICIPANTS

The Copenhagen Baby Heart Study was a cross-sectional, population-based study open to all newborns born in Copenhagen between April 1, 2016, and October 31, 2018. Newborns with BAV were matched 1:2 to newborns with a tricuspid aortic valve (non-BAV group) on sex, singleton/twin pregnancy, gestational age, weight, and age at time of examination.

EXPOSURES

Transthoracic echocardiography within 60 days after birth.

MAIN OUTCOMES AND MEASURES

Primary outcome was BAV prevalence and types, ie, number of raphes and spatial orientation of raphes or cusps (no raphes), according to the classification system of Sievers and Schmidtke (classified as type 0, 1, or 2, with numbers indicating the number of raphes). Secondary outcome was valve function and BAV-associated aortopathy, defined as aortic diameter z score of 3 or greater or coarctation.

RESULTS

In total, 25 556 newborns (51.7% male; mean age, 12 [SD, 8] days) underwent echocardiography. BAV was diagnosed in 196 newborns (prevalence, 0.77% [95% CI, 0.67%-0.88%]), with male-female ratio 2.1:1. BAV was classified as type 0 in 17 newborns (8.7% [95% CI, 5.5%-13.5%]), type 1 in 178 (90.8% [95% CI, 86.0%-94.1%]) (147 [75.0% {95% CI, 68.5%-80.5%}] right-left coronary raphe, 27 [13.8% {95% CI, 9.6%-19.3%}] right coronary-noncoronary raphe, 4 [2.0% {95% CI, 0.8%-5.1%}] left coronary-noncoronary raphe), and type 2 in 1 (0.5% [95% CI, 0.1%-2.8%]). Aortic regurgitation was more prevalent in newborns with BAV (n = 29 [14.7%]) than in those without BAV (1.3%) (absolute % difference, 13.4% [95% CI, 7.8%-18.9%]; P < .001). Newborns with BAV had higher flow velocities across the valve (0.67 [95% CI, 0.65-0.69] m/s vs 0.61 [95% CI, 0.60-0.62] m/s; mean difference, 0.06 m/s [95% CI, 0-0.1]) and larger aortic root and tubular ascending aortic diameters than those without BAV (10.7 [95% CI, 10.7-10.9] mm vs 10.3 [95% CI, 10.2-10.4] mm; mean difference, 0.43 mm [95% CI, 0.2-0.6 mm] and 9.8 [95% CI, 9.6-10.0] mm vs 9.4 [95% CI, 9.3-9.5] mm; mean difference, 0.46 mm [95% CI, 0.30-0.70], respectively) (P < .001 for all). Aortopathy was seen in 65 newborns (33.2%) with BAV (62 with aortic z score ≥3; 3 with coarctation).

CONCLUSIONS AND RELEVANCE

Among newborns in Copenhagen, the prevalence of BAV was 0.77%. Aortopathy was common in newborns with BAV, suggesting that it also represents a fetal malformation.

Proteomic Analysis Reveals that Di Dang Decoction Protects Against Acute Intracerebral Hemorrhage Stroke in Rats by Regulating S100a8, S100a9 Col1a1, and Col1a2

OBJECTIVE

The present study aimed to explore the neuroprotective mechanism of Di Dang decoction (DDD) during acute intracerebral hemorrhage (AICH) stroke in Sprague Dawley rats through proteomic analysis.

METHODS

A total of 135 healthy Sprague Dawley rats were randomly divided into five groups: control (n = 27), model (n = 27), DDD low-dose (n = 27), DDD medium-dose (n = 27), and DDD high-dose (n = 27). AICH stroke in rats was induced by injecting autologous blood into the caudate nucleus. The modified Neurological Severity Score (mNSS) was used to evaluate the cerebral nerve function deficit. Hematoxylin and eosin (HE) staining was performed to observe the brain tissue at the lesion site. Albumin concentration was assessed on obvious blood-brain barrier damaged and brain water content was used to evaluate the brain injury. For quantitative proteomics, proteins were extracted from the cerebral cortices. Target proteins were identified using mass spectrometer-based targeted proteomic quantification.

RESULTS

mNSS score, HE staining results, albumin concentration, and brain water content showed the most significant improvements in the neuroprotective in the high-dose group 7 days after DDD exposure. Furthermore, quantitative proteomics analysis showed that, relative to the control group, S100a8 and S100a9 were downregulated by 0.614 (p = 0.033702) and 0.506 times (p = 0.000024) in the high-dose group. Compared with the control group, Col1a1 and Col1a2 were upregulated by 1.319 (p = 0.000184) and 1.348 (p = 0.014097) times in the high-dose group. These results were confirmed using mass spectrometer-based targeted proteomic quantification.

CONCLUSION

Application of a high-dose DDD for 7 days in AICH stroke rats showed the most significant improvements in neuroprotective. Mechanistically, this effect was mediated by S100a8 and S100a9 protein downregulation and Col1a1 and Col1a2 upregulation.

Regurgitant Bicuspid Aortopathy: Is Valve-Sparing Root Replacement Equivalent to Bentall Procedure?

BACKGROUND

Repair of aortic root aneurysms with nonstenotic bicuspid valves (NS-BAVs) is achieved either with valve-sparing root replacement (VSRR) or conventional Bentall procedure (ROOT). Procedural and long-term outcomes comparing these 2 techniques are sparse and need investigation.

METHODS

From March 2004 to January 2019, 158 patients with an aortic root aneurysm and NS-BAV underwent VSRR (n = 78, 49.3%) or ROOT (n = 80, 50.6%). VSRR involved optional aortic valve repair (n = 47, 60%), and ROOT was performed with bioprosthetic (81.3%) or mechanical valve replacement (18.7%). Procedural and postoperative outcomes were obtained, and univariate and Kaplan-Meier analyses were performed.

RESULTS

VSRR patients were younger (42.7 ± 12.0 years of age) than ROOT (54.8 ± 13.6 years of age) (P < .001). Cardiopulmonary bypass (CPB) and cross-clamp duration were longer in VSRR (CPB: 228.0 ± 39.1 minutes; cross-clamp: 200.1 ± 36.2 minutes) compared with ROOT (CPB: 199.5 ± 55 minutes; cross-clamp: 170.3 ± 39.5 minutes) (P < .001). Postoperative stroke, renal failure, pneumonia, and reoperation for bleeding were similar, but postoperative atrial and ventricular arrhythmias was lower in VSRR (15% vs 42%; P < .001). Length of stay and 30-day mortality were similar. At discharge, none had greater than trivial aortic insufficiency. Long-term 10-year survival and incidence of moderate-severe aortic insufficiency, aortic stenosis, and reoperation were equivalent between groups.

CONCLUSIONS

Surgery for aortopathy associated with NS-BAV is safe and effective with either VSRR or ROOT. Despite its complexity, VSRR should be considered in the surgical treatment of this population.

Modeling aortic diseases using induced pluripotent stem cells

Induced pluripotent stem cells (iPSCs) offer an effective platform for studies of human physiology and have revealed new possibilities for disease modeling at the cellular level. These cells also have the potential to be leveraged in the practice of precision medicine, including personalized drug testing. Aortic diseases result in significant morbidity and mortality and pose a global burden to healthcare. Their pathogenesis is mostly associated with functional alterations of vascular components, such as endothelial cells and vascular smooth muscle cells. Drugs that have been proven to be effective in animal models often fail to protect patients from adverse aortic events in clinical studies, provoking researchers to develop reliable in vitro models using human cells. In this review, we summarize the patient iPSC-derived aortic cells that have been utilized to model aortic diseases in vitro. In advanced models, hemodynamic factors, such as blood flow-induced shear stress and cyclic strain, have been added to the systems to replicate cellular microenvironments in the aortic wall. Examples of the utility of such factors in modeling various aortopathies, such as Marfan syndrome, Loeys-Dietz syndrome, and bicuspid aortic valve-related aortopathy, are also described. Overall, the iPSC-based in vitro cell models have shown the potential to promote the development and practice of precision medicine in the treatment of aortic diseases.

Genetic Polymorphisms of MMP1, MMP9, COL1A1, and COL1A2 in Polish Patients with Thoracic Aortopathy

BACKGROUND

The pathogenesis of thoracic aortopathy is complex, and much evidence suggests the influence of genetic factors. Some genes with polymorphisms are widely considered critical factors in the initiation and development of aortic aneurysm. The aim of our study was to analyze the association of genetic polymorphisms of MMP1 rs1799750 (c.-1607G>GG), MMP9 rs3918242 (c.-1562C>T), COL1A1 rs1800012 (c.1245G>T), and COL1A2 rs42524 (c.1645G>C) with predisposition to thoracic aortopathy in Polish patients and with clinical characteristics of these patients.

METHODS

The study was carried out with 96 patients with thoracic aortopathy (47 patients with ascending aortic aneurysm and 49 patients with thoracic aortic dissection) and 61 control subjects without thoracic aortopathy. The MMP1, MMP9, COL1A1, and COL1A2 polymorphisms were determined by PCR-RFLP.

RESULTS

No significant differences in the frequency distributions of MMP1, MMP9, COL1A1, and COL1A2 genotypes or alleles were found (1) between the control group and patients with ascending aortic aneurysm (AsAA), (2) between the control group and patients with thoracic aortic dissection (TAD), or (3) between AsAA and TAD patients. Multivariate logistic regression analysis revealed that MMP1 and MMP9 polymorphisms were associated with the degree of aortic valve regurgitation.

CONCLUSION

The results of our study did not support associations between MMP1, MMP9, COL1A1, and COL1A2 genetic variants with the risk of thoracic artery disease in Polish patients. However, rs1799750 MMP1 and rs3918242 MMP9 seem to be associated with the degree of aortic regurgitation.

Bicuspid Aortic Valve and Endothelial Dysfunction: Current Evidence and Potential Therapeutic Targets

Bicuspid aortic valve (BAV), the most frequent congenital heart malformation, is characterized by the presence of a two-leaflet aortic valve instead of a three-leaflet one. BAV disease progression is associated with valvular dysfunction (in the form of stenosis or regurgitation) and aortopathy, which can lead to aneurysm and aortic dissection. This morphological abnormality modifies valve dynamics and promotes eccentric blood flow, which gives rise to alterations of the flow pattern and wall shear stress (WSS) of the ascending aorta. Recently, evidence of endothelial dysfunction (ED) in BAV disease has emerged. Different studies have addressed a reduced endothelial functionality by analyzing various molecular biomarkers and cellular parameters in BAV patients. Some authors have found impaired functionality of circulating endothelial progenitors in these patients, associating it with valvular dysfunction and aortic dilation. Others focused on systemic endothelial function by measuring artery flow-mediated dilation (FMD), showing a reduced FMD in BAV individuals. Novel biomarkers like increased endothelial microparticles (EMP), which are related to ED, have also been discovered in BAV patients. Finally, latest studies indicate that in BAV, endothelial-to-mesenchymal transition (EndoMT) may also be de-regulated, which could be caused by genetic, hemodynamic alterations, or both. Different hypothesis about the pathology of ED in BAV are nowadays being debated. Some authors blamed this impaired functionality just on genetic abnormalities, which could lead to a pathological aorta. Nevertheless, thanks to the development of new and high-resolution imaging techniques like 4D flow MRI, hemodynamics has gained great attention. Based on latest studies, alterations in blood flow seem to cause proper modification of the endothelial cells (ECs) function and morphology. It also seems to be associated with aortic dilation and decreased vasodilators expression, like nitric oxide (NO). Although nowadays ED in BAV has been reported by many, it is not clear which its main cause may be. Comprehending the pathways that promote ED and its relevance in BAV could help further understand and maybe prevent the serious consequences of this disease. This review will discuss the ED present in BAV, focusing on the latest evidence, biomarkers for ED and potential therapeutic targets (Figure 1).

Thoracic Aortic Aneurysm Growth in Bicuspid Aortic Valve Patients: Role of Aortic Stiffness and Pulsatile Hemodynamics

Background

Bicuspid aortic valve (BAV) is the most common congenital cardiac abnormality. A thoracic aortic aneurysm (TAA) is present in ≈50% of BAV patients, who also have an 8‐fold higher risk of aortic dissection than the general population. Because the health of the aorta is directly reflected in its stiffness and pulsatile hemodynamics, we hypothesized that measures of aortic stiffness and arterial load would be associated with TAA growth in BAV.

Methods and Results

Twenty‐nine unoperated participants with TAA due to BAV who had serial imaging were recruited. Aortic stiffness and steady and pulsatile arterial load were evaluated with validated methods that integrate arterial tonometry with echocardiography. TAA growth was assessed retrospectively based on available imaging, blinded to hemodynamic status. Multivariable linear regression assessed associations of aortic stiffness and hemodynamic variables with TAA growth, adjusting for potential confounders. Overall, 66% of participants were men. Mean±SD for age, baseline aneurysm size, growth rate, and follow‐up time were 57.2±8.3 years, 46.9±3.6 mm, 0.75±0.81 mm/y, and 2.9±3.3 years, respectively. We found that greater aortic stiffness (β±SE for carotid‐femoral pulse wave velocity: 0.30±0.13. P=0.03) and aortic characteristic impedance (β±SE: 0.46±0.18, P=0.02), as well as lower total arterial and proximal aortic compliance (β±SE: −0.44±0.21, P=0.05, and −0.63±0.16, P=0.001, respectively) were independently associated with faster aneurysm growth.

Conclusions

In patients with TAA due to BAV, measures of greater aortic stiffness and pulsatile arterial load indicate an association with accelerated aneurysm expansion. Assessing arterial hemodynamics may be useful for risk stratification and disease monitoring in TAA patients with BAV.

Aortopathy in Congenital Heart Disease

Aortic dilatation is common in patients with congenital heart disease and is seen in patients with bicuspid aortic valve and those with conotruncal congenital heart defects. It is important to identify patients with bicuspid aortic valve at high risk for aortic dissection. High-risk patients include those with the aortic root phenotype and those with syndromic or familial aortopathies including Marfan syndrome, Loeys-Dietz syndrome, and Turner syndrome. Aortic dilatation is common in patients with conotruncal congenital heart defects and rarely results in aortic dissection.

Genetics in bicuspid aortic valve disease: Where are we?

Bicuspid aortic valve (BAV) is the most common congenital heart defect, found in up to 2% of the population and associated with a 30% lifetime risk of complications. BAV is inherited as an autosomal dominant trait with incomplete penetrance and variable expressivity due to a complex genetic architecture that involves many interacting genes. In this review, we highlight the current state of knowledge about BAV genetics, principles and methods for BAV gene discovery, clinical applications of BAV genetics, and important future directions.

The importance of genetics and genetic counselors in the evaluation of patients with bicuspid aortic valve and aortopathy

PURPOSE OF REVIEW

Bicuspid aortic valve (BAV) is a common congenital heart defect, with an estimated frequency of 1-2% in the general population. BAV may occur as an isolated finding or as a feature of certain syndromes. This article discusses potential genetic causes of BAV, includes a list of current known and candidate genes associated with BAV, provides a hypothetical case demonstrating the importance of genetic testing and cascade screening, and highlights the value of genetic counselors specializing in cardiovascular genetics.

RECENT FINDINGS

Individuals with BAV are at significantly increased risk of progressive aortic valve disease and aortic root aneurysms. There is high heritability associated with BAV, and several specific genes have recently been associated with BAV. There is wide phenotypic variability among BAV malformations, including which cusps are involved and the degree of aortic root involvement. Genotype-phenotype correlations exist that impact treatment recommendations. Genetic testing can reduce morbidity and mortality by guiding management strategies and identifying asymptomatic relatives before significant complications occur.

SUMMARY

Identifying cases of BAV with an identifiable genetic cause can significantly impact patients and family members. The list of associated genes is constantly growing. Genetic counselors have an important role in the evaluation of families at risk of BAV.

Genetic Contribution to Congenital Heart Disease (CHD)

Congenital heart defects (CHD) are the most common congenital problems in neonates. The basis for CHD is multifactorial, involving genetic and environmental components. The elucidation of genetic components remains difficult because it is a genetically heterogeneous disease. Currently, the major identified genetic causes include chromosomal abnormalities, large subchromosomal deletions/duplications, and point mutations. However, much more remains to be unraveled. An important insight from the research on the genetics of CHD is that any change at the genetic level that alters the dosage of genes required in any process during heart development results in a developmental defect. The use of conventional gene identification (linkage analysis and direct targeted sequencing) methods followed by the rapid advancements in high-throughput technologies (copy number variant platforms, SNP arrays, and next-generation sequencing) has identified an extensive list of genetic causes. However, the most common presentation of CHD is in the form of sporadic cases. Therefore, it is important to identify their underlying genetic cause. In this review, we revisit the causal genetic factors of CHD and discuss the clinical implications of research in the field.

Endothelial/Epithelial Mesenchymal Transition in Ascending Aortas of Patients With Bicuspid Aortic Valve

Thoracic aortic aneurysm (TAA) is the progressive enlargement of the aorta due to destructive changes in the connective tissue of the aortic wall. Aneurysm development is silent and often first manifested by the drastic events of aortic dissection or rupture. As yet, therapeutic agents that halt or reverse the process of aortic wall deterioration are absent, and the only available therapeutic recommendation is elective prophylactic surgical intervention. Being born with a bicuspid instead of the normal tricuspid aortic valve (TAV) is a major risk factor for developing aneurysm in the ascending aorta later in life. Although the pathophysiology of the increased aneurysm susceptibility is not known, recent studies are suggestive of a transformation of aortic endothelium into a more mesenchymal state i.e., an endothelial-to-mesenchymal transition in these individuals. This process involves the loss of endothelial cell features, resulting in junction instability and enhanced vascular permeability of the ascending aorta that may lay the ground for increased aneurysm susceptibility. This finding differentiates and further emphasizes the specific characteristics of aneurysm development in individuals with a bicuspid aortic valve (BAV). This review discusses the possibility of a developmental fate shared between the aortic endothelium and aortic valves. It further speculates about the impact of aortic endothelium phenotypic shift on aneurysm development in individuals with a BAV and revisits previous studies in the light of the new findings.

Notch signaling in the pathogenesis of thoracic aortic aneurysms: A bridge between embryonic and adult states

Aneurysms of the thoracic aorta are a "silent killer" with no evident clinical signs until the fatal outcome. Molecular and genetic bases of thoracic aortic aneurysms mainly include transforming growth factor beta signaling, smooth muscle contractile units and metabolism genes, and extracellular matrix genes. In recent studies, a role of Notch signaling, among other pathways, has emerged in disease pathogenesis. Notch is a highly conserved signaling pathway that regulates the development and differentiation of many types of tissues and influences major cellular processes such as cell proliferation, differentiation and apoptosis. Mutations in several Notch signaling components have been associated with a number of heart defects, demonstrating an essential role of Notch signaling both in cardiovascular system development and its maintenance during postnatal life. This review discusses the role of Notch signaling in the pathogenesis of thoracic aortic aneurysms considering development and maintenance of the aortic root and how developmental regulations by Notch signaling may influence thoracic aortic aneurysms.

The American Association for Thoracic Surgery consensus guidelines on bicuspid aortic valve-related aortopathy: Full online-only version

Bicuspid aortic valve disease is the most common congenital cardiac disorder, being present in 1% to 2% of the general population. Associated aortopathy is a common finding in patients with bicuspid aortic valve disease, with thoracic aortic dilation noted in approximately 40% of patients in referral centers. Several previous consensus statements and guidelines have addressed the management of bicuspid aortic valve-associated aortopathy, but none focused entirely on this disease process. The current guidelines cover all major aspects of bicuspid aortic valve aortopathy, including natural history, phenotypic expression, histology and molecular pathomechanisms, imaging, indications for surgery, surveillance, and follow-up, and recommendations for future research. It is intended to provide clinicians with a current and comprehensive review of bicuspid aortic valve aortopathy and to guide the daily management of these complex patients.

microRNAs in bicuspid aortic valve associated aortopathy: Recent advances and future perspectives

The risk of acute aortic events in patients with bicuspid aortic valve (BAV) constitutes a medical concern in terms of timing and surgical decision. During the past years, there has been a growing interest in the potential of microRNAs (miRNAs) as crucial epigenetic factors in multiple cellular processes associated with BAV aortopathy. Nevertheless, there are still challenges that need to be overcome before miRNAs could enter clinical practice, and further validation studies in larger and well-defined BAV cohorts are now required. This review aims at providing a comprehensive overview of the available data on the expression profiles and function of specific miRNAs in BAV aortopathy, evaluating miRNA signatures as potential molecular markers of disease. We also discuss the role of other novel classes of non-coding RNAs, including long non-coding RNAs and circular RNAs, in BAV-associated aortopathy, mainly regarding their possible implementation as diagnostic and prognostic markers.

Clinical-pathological correlations of BAV and the attendant thoracic aortopathies. Part 2: Pluridisciplinary perspective on their genetic and molecular origins

Bicuspid aortic valve (BAV) arises during valvulogenesis when 2 leaflets/cusps of the aortic valve (AOV) are fused together. Its clinical manifestations pertain to faulty AOV function, the associated aortopathy, and other complications surveyed in Part 1 of the present bipartite-series. Part 2 examines mainly genetic and epigenetic causes of BAV and BAV-associated aortopathies (BAVAs) and disease syndromes (BAVD). Part 1 explored the heterogeneity among subsets of patients with BAV and BAVA/BAVD, and investigated abnormal fluid dynamic stress and strain patterns sustained by the cusps. Specific BAV morphologies engender systolic outflow asymmetries, associated with abnormal aortic regional wall-shear-stress distributions and the expression/localization of BAVAs. Understanding fluid dynamic factors besides the developmental mechanisms and underlying genetics governing these congenital anomalies is necessary to explain patient predisposition to aortopathy and phenotypic heterogeneity. BAV aortopathy entails complex/multifactorial pathophysiology, involving alterations in genetics, epigenetics, hemodynamics, and in cellular and molecular pathways. There is always an interdependence between organismic developmental signals and genes-no systemic signals, no gene-expression; no active gene, no next step. An apposite signal induces the expression of the next developmental gene, which needs be expressed to trigger the next signal, and so on. Hence, embryonic, then post-partum, AOV and thoracic aortic development comprise cascades of developmental genes and their regulation. Interdependencies between them arise, entailing reciprocal/cyclical mutual interactions and adaptive feedback loops, by which developmental morphogenetic processes self-correct responding to environmental inputs/reactions. This Survey can serve as a reference point and driver for further pluridisciplinary BAV/BAVD studies and their clinical translation.

An Exploratory Look at Bicuspid Aortic Valve (Bav) Aortopathy: Focus on Molecular and Cellular Mechanisms

Bicuspid aortic valve (BAV) is the most common congenital heart malformation. BAV patients are at increased risk for aortic valve disease (stenosis/regurgitation), infective endocarditis, thrombi formation and, in particular, aortic dilatation, aneurysm and dissection. This review aims at exploring the possible interplay among genetics, extracellular matrix remodeling, abnormal signaling pathways, oxidative stress and inflammation in contributing to BAV-associated aortopathy (BAV-A-A). Novel circulating biomarkers have been proposed as diagnostic tools able to improve risk stratification in BAV-A-A. However, to date, the precise molecular and cellular mechanisms that lead to BAV-A-A remain unknown. Genetic, hemodynamic and cardiovascular risk factors have been implicated in the development and progression of BAV-A-A. Oxidative stress may also play a role, similarly to what observed in atherosclerosis and vulnerable plaque formation. The identification of common pathways between these 2 conditions may provide a platform for future therapeutic solutions.

Is there a role for autophagy in ascending aortopathy associated with tricuspid or bicuspid aortic valve?

Autophagy is a conserved process by which cytoplasmatic elements are sequestered in vesicles and degraded after their fusion with lysosomes, thus recycling the precursor molecules. The autophagy-mediated removal of redundant/harmful/damaged organelles and biomolecules plays not only a replenishing function, but protects against stressful conditions through an adaptive mechanism. Autophagy, known to play a role in several pathological conditions, is now gaining increasing attention also in the perspective of the identification of the pathogenetic mechanisms at the basis of ascending thoracic aortic aneurysm (TAA), a localized or diffused dilatation of the aorta with an abnormal widening greater than 50 percent of the vessel's normal diameter. TAA is less frequent than abdominal aortic aneurysm (AAA), but is encountered with a higher percentage in patients with congenital heart disease or known genetic syndromes. Several biological aspects of TAA pathophysiology remain to be elucitated and therapeutic needs are still widely unmet. One of the most controversial and epidemiologically important forms of TAA is that associated with the congenital bicuspid malformation of the aortic valve (BAV). Dysregulated autophagy in response, for example, to wall shear stress alterations, has been demonstrated to affect the phenotype of vascular cells relevant to aortopathy, with potential consequences on signaling, remodeling, and angiogenesis. The most recent findings and hypotheses concerning the multiple aspects of autophagy and of its dysregulation are summarized, both in general and in the context of the different vascular cell types and of TAA progression, with particular reference to BAV-related aortopathy.

Segmental aortic stiffness in patients with bicuspid aortic valve compared with first-degree relatives

Aims

To compare the stiffness index in patients with bicuspid aortic valve (BAV) with first-degree relatives at each segment of the thoracic ascending aorta and to compare segmental analysis of aortic stiffness in association with BAV morphotype and function.

Methods

219 patients with BAV and 148 first-degree relatives (without BAV) were consecutively included at a reference centre for BAV. Ultrasound assessment of aortic and carotid stiffness was based on the variation of the segmental arterial diameters during the cardiac cycle and on blood pressure.

Results

Without adjustment, the ascending aorta of patients with BAV seemed stiffer at each segment compared with controls (stiffness index at the sinus of Valsalva: 17.0±10.9 vs 8.9±6.1, p<0.001; tubular aorta: 20.4±31.3 vs 12.7±4.8, p=0.04). However, after adjustment on aortic diameter and age, only the sinus of Valsalva remained stiffer (p<0.001), whereas the tubular aorta no longer differed (p=0.610). In patients with BAV, aortic diameters were not influenced by the valve morphotype, except for the arch, which was more dilated in the case of 1- Non coronary sinus-Right subtype of BAV : 36.1 vs 27.6 mm, p<0.001. Aortic regurgitation was associated with an increase in aortic diameters at the sinus of Valsalva (p<0.001) and the tubular aortic levels (p=0.04).

Conclusion

Stiffness increase at the sinus of Valsalva level is independent of aortic dilatation in patients with BAV, contrary to the classic relationship between stiffness and dilatation found on the other segments. The relationship between stiffness and clinical impact needs to be assessed at each aortic segment.

Preconception Counseling for Patients With Thoracic Aortic Aneurysms

PURPOSE OF THE REVIEW

Acute aortic dissection is a potentially catastrophic cardiovascular emergency that is associated with a high mortality rate. Pregnancy, with its attendant hormonal and physiological changes, increases the risk of dissection in women with known thoracic aortic aneurysms. In this review, we highlight the importance of preconception counseling to help women with known thoracic aortic aneurysms better understand their risk of dissection and the heritable nature of thoracic aortic disease and its associated syndromes.

RECENT FINDINGS

The risk of aortic dissection during pregnancy differs according to the underlying etiology of thoracic aortic aneurysm and the degree of aortic dilatation at baseline. Guideline-specific management of women with thoracic aortic aneurysms in pregnancy reduces their risk of dissection. Management of pregnant women with thoracic aortic aneurysms requires an intensive multidisciplinary approach to maximize the chances of a successful outcome for both the mother and fetus. Preconception counseling provides an opportunity to optimize patients medically and to consider potential prophylactic aortic repair prior to pregnancy.

Targeted Next-Generation Sequencing in Patients with Non-syndromic Congenital Heart Disease

Congenital heart disease (CHD) is a genetically heterogeneous disease. Targeted next-generation sequencing (NGS) offers a unique opportunity to sequence multiple genes at lower cost and effort compared to Sanger sequencing. We tested a targeted NGS of a specific gene panel in a relatively large population of non-syndromic CHD patients. The patient cohort comprised 68 CHD patients (45 males; 8.3 ± 1.7 years). Amplicon libraries for 16 CHD-strictly related genes were generated using a TruSeq^® Custom Amplicon kit (Illumina, CA) and sequenced using the Illumina MiSeq platform. Sequence data were processed through the MiSeq Reporter and wANNOVAR softwares. After applying stringent filtering criteria, 20 missense variants in 9 genes were predicted to be damaging and were validated by Sanger sequencing with 100% concordance. Fourteen variants were present in public databases with very rare allele frequency, of which four variants (p.Arg25Cys in NKX2-5, p.Val763Ile in ZFPM2, p.Arg1398Gln and Gly1826Asp in MYH6) have been previously linked to CHD or cardiomyopathy. The remaining six variants in four genes (GATA4, NKX2-5, NOTCH1, TBX1) were novel mutations, currently not found in public databases, and absent in 200 control alleles of healthy subjects. Four patients (5.8%) carried two missense variants (1 compound heterozygote in the same gene and 3 double heterozygotes in different genes), with possibly synergistic deleterious effects. Targeted NGS is a powerful and efficient tool to detect DNA sequence variants in multiple genes, providing the opportunity for discovery of the co-occurrence of two or more missense rare variants.

Physiology of Cardiac Development: From Genetics to Signaling to Therapeutic Strategies

The heart is one of the first organs to form and function during embryonic development. It is comprised of multiple cell lineages, each integral for proper cardiac development, and include cardiomyocytes, endothelial cells, epicardial cells and neural crest cells. The molecular mechanisms regulating cardiac development and morphogenesis are dependent on signaling crosstalk between multiple lineages through paracrine interactions, cell-ECM interactions, and cell-cell interactions, which together, help facilitate survival, growth, proliferation, differentiation and migration of cardiac tissue. Aberrant regulation of any of these processes can induce developmental disorders and pathological phenotypes. Here, we will discuss each of these processes, the genetic factors that contribute to each step of cardiac development, as well as the current and future therapeutic targets and mechanisms of heart development and disease. Understanding the complex interactions that regulate cardiac development, proliferation and differentiation is not only vital to understanding the causes of congenital heart defects, but to also finding new therapeutics that can treat both pediatric and adult cardiac disease in the near future.

miRNome Profiling in Bicuspid Aortic Valve-Associated Aortopathy by Next-Generation Sequencing

The molecular mechanisms underlying thoracic aortic aneurysm (TAA) in patients with bicuspid aortic valve (BAV) are incompletely characterized. MicroRNAs (miRNAs) may play a major role in the different pathogenesis of aortopathy. We sought to employ next-generation sequencing to analyze the entire miRNome in TAA tissue from patients with BAV and tricuspid aortic valve (TAV). In the discovery stage, small RNA sequencing was performed using the Illumina MiSeq platform in 13 TAA tissue samples (seven patients with BAV and six with TAV). Gene ontology (GO) and KEGG pathway analysis were used to identify key pathways and biological functions. Validation analysis was performed by qRT-PCR in an independent cohort of 30 patients with BAV (26 males; 59.5 ± 12 years) and 30 patients with TAV (16 males; 68.5 ± 9.5 years). Bioinformatic analysis identified a total of 489 known mature miRNAs and five novel miRNAs. Compared to TAV samples, 12 known miRNAs were found to be differentially expressed in BAV, including two up-regulated and 10 down-regulated (FDR-adjusted p-value ≤ 0.05 and fold change ≥  1.5). GO and KEGG pathway enrichment analysis (FDR-adjusted p-value < 0.05) identified different target genes and pathways linked to BAV and aneurysm formation, including Hippo signaling pathway, ErbB signaling, TGF-beta signaling and focal adhesion. Validation analysis of selected miRNAs confirmed the significant down-regulation of miR-424-3p (p = 0.01) and miR-3688-3p (p = 0.03) in BAV patients as compared to TAV patients. Our study provided the first in-depth screening of the whole miRNome in TAA specimens and identified specific dysregulated miRNAs in BAV patients.

Genetic Disorders of the Thoracic Aorta and Indications for Surgery

Genetic disorders of the aorta are rare but can lead to life-threatening thoracic aortic aneurysms. Although the genetic causes of many of these connective tissue diseases are well defined, others such as familial thoracic aortic aneurysm and bicuspid aortic valve aortopathy are not. The natural history of genetic thoracic aortic aneurysms is not well understood or predictable, and surgical guidelines for treatment remain imprecise. Future research should strive to provide in-depth and detailed genetic profiling to drive clinical management, including medical and surgical therapies.

Different Notch signaling in cells from calcified bicuspid and tricuspid aortic valves

AIMS

Calcific aortic valve disease is the most common heart valve disease in the Western world. Bicuspid and tricuspid aortic valve calcifications are traditionally considered together although the dynamics of the disease progression is different between the two groups of patients. Notch signaling is critical for bicuspid valve development and NOTCH1 mutations are associated with bicuspid valve and calcification. We hypothesized that Notch-dependent mechanisms of valve mineralization might be different in the two groups.

METHODS AND RESULTS

We used aortic valve interstitial cells and valve endothelial cells from patients with calcific aortic stenosis with bicuspid or tricuspid aortic valve. Expression of Notch-related genes in valve interstitial cells by qPCR was different between bicuspid and tricuspid groups. Discriminant analysis of gene expression pattern in the interstitial cells revealed that the cells from calcified bicuspid valves formed a separate group from calcified tricuspid and control cells. Interstitial cells from bicuspid calcified valves demonstrated significantly higher sensitivity to stimuli at early stages of induced proosteogenic differentiation and were significantly more sensitive to the activation of proosteogenic OPN, ALP and POSTIN expression by Notch activation. Notch-activated endothelial-to-mesenchymal transition and the corresponding expression of HEY1 and SLUG were also more prominent in bicuspid valve derived endothelial cells compared to the cells from calcified tricuspid and healthy valves.

CONCLUSION

Early signaling events including Notch-dependent mechanisms that are responsible for the initiation of aortic valve calcification are different between the patients with bicuspid and tricuspid aortic valves.

Targeted next-generation sequencing identified ADAMTS5 as novel genetic substrate in patients with bicuspid aortic valve

BACKGROUND

Bicuspid Aortic Valve (BAV) is the most common congenital heart disease, affecting >1% of the general population. Up to date, three genes, NOTCH1, GATA5 and SMAD6, have been linked to the isolated form of BAV. However, potential genetic determinants remain largely unknown in most BAV patients.

MATERIAL AND METHODS

Targeted next-generation sequencing of 7 BAV candidate genes (NOTCH1, GATA5, SMAD6, NOS3, ADAMTS5, Alk2 and SMAD2) was performed in 32 BAV patients. Additional 35 BAV patients and 238 tricuspid aortic valve (TAV) patients, consisting of 107 patients from the transcatheter aortic valve implantation (TAVI) registry and 131 patients from the coronary artery disease (CAD) registry, were selected for further genotyping.

RESULTS

We found 2 rare non-synonymous variants in 2/7 genes in 3 BAV patients: one was NOTCH1:c.4297G>A and the other one was ADMTS5:c.935C>A that shared by two patients. NOTCH1:c.4297G>A has not been reported previously. ADMTS5:c.935C>A was predicted to be pathogenic by all applied algorithms. Alignment of protein sequences from all available species revealed that ADMTS5:p.Arg312Leu, produced by ADMTS5:c.935C>A, is located in a highly conserved region. The minor allele frequency of ADMTS5:c.935C>A in BAV patients was significantly higher than the matched population in TAV group (0.015 vs. 0, P=0.048).

CONCLUSION

Our results suggested that ADMTS5:c.935C>A are potentially associated with BAV. Further studies, such as large sample case-control replication test and functional research, are needed to explore the role of this rare variant in the development of BAV.

Genetic Bases of Bicuspid Aortic Valve: The Contribution of Traditional and High-Throughput Sequencing Approaches on Research and Diagnosis

Bicuspid aortic valve (BAV) is a common (0.5-2.0% of general population) congenital heart defect with increased prevalence of aortic dilatation and dissection. BAV has an autosomal dominant inheritance with reduced penetrance and variable expressivity. BAV has been described as an isolated trait or associated with syndromic conditions [e.g., Marfan Marfan syndrome or Loeys-Dietz syndrome (MFS, LDS)]. Identification of a syndromic condition in a BAV patient is clinically relevant to personalize aortic surgery indication. A 4-fold increase in BAV prevalence in a large cohort of unrelated MFS patients with respect to general population was reported, as well as in LDS patients (8-fold). It is also known that BAV is more frequent in patients with thoracic aortic aneurysm (TAA) related to mutations in ACTA2, FBN1, and TGFBR2 genes. Moreover, in 8 patients with BAV and thoracic aortic dilation, not fulfilling the clinical criteria for MFS, FBN1 mutations in 2/8 patients were identified suggesting that FBN1 or other genes involved in syndromic conditions correlated to aortopathy could be involved in BAV. Beyond loci associated to syndromic disorders, studies in humans and animal models evidenced/suggested the role of further genes in non-syndromic BAV. The transcriptional regulator NOTCH1 has been associated with the development and acceleration of calcium deposition. Genome wide marker-based linkage analysis demonstrated a linkage of BAV to loci on chromosomes 18, 5, and 13q. Recently, a role for GATA4/5 in aortic valve morphogenesis and endocardial cell differentiation has been reported. BAV has also been associated with a reduced UFD1L gene expression or involvement of a locus containing AXIN1/PDIA2. Much remains to be understood about the genetics of BAV. In the last years, high-throughput sequencing technologies, allowing the analysis of large number of genes or entire exomes or genomes, progressively became available. The latter issue together with the development of "BigData" analysis methods improving their interpretation and integration with clinical data represents a promising opportunity to increase the disease knowledge and diagnosis in monogenic and multifactorial complex traits. This review summarized the main knowledge on the BAV genetic bases, the role of genetic diagnosis in BAV patient managements and the crucial challenges for the comprehension of genetics of BAV in research and diagnosis.

Mechanisms of Smooth Muscle Cell Differentiation Are Distinctly Altered in Thoracic Aortic Aneurysms Associated with Bicuspid or Tricuspid Aortic Valves

Cellular and molecular mechanisms of thoracic aortic aneurysm are not clear and therapeutic approaches are mostly absent. Thoracic aortic aneurysm is associated with defective differentiation of smooth muscle cells (SMC) of aortic wall. Bicuspid aortic valve (BAV) comparing to tricuspid aortic valve (TAV) significantly predisposes to a risk of thoracic aortic aneurysms. It has been suggested recently that BAV-associated aortopathies represent a separate pathology comparing to TAV-associated dilations. The only proven candidate gene that has been associated with BAV remains NOTCH1. In this study we tested the hypothesis that Notch-dependent and related TGF-β and BMP differentiation pathways are differently altered in aortic SMC of BAV- vs. TAV-associated aortic aneurysms. SMC were isolated from aortic tissues of the patients with BAV- or TAV-associated aortic aneurysms and from healthy donors used as controls. Gene expression was verified by qPCR and Western blotting. For TGF-β induced differentiation SMC were treated with the medium containing TGF-β1. To induce proosteogenic signaling we cultured SMC in the presence of specific osteogenic factors. Notch-dependent differentiation was induced via lentiviral transduction of SMC with activated Notch1 domain. MYOCD expression, a master gene of SMC differentiation, was down regulated in SMC of both BAV and TAV patients. Discriminant analysis of gene expression patterns included a set of contractile genes specific for SMC, Notch-related genes and proosteogenic genes and revealed that control cells form a separate cluster from both BAV and TAV group, while BAV- and TAV-derived SMC are partially distinct with some overlapping. In differentiation experiments TGF-β caused similar patterns of target gene expression for BAV- and TAV derived cells while the induction was higher in the diseased cells than in control ones. Osteogenic induction caused significant change in RUNX2 expression exclusively in BAV group. Notch activation induced significant ACTA2 expression also exclusively in BAV group. We show that Notch acts synergistically with proosteogenic factors to induce ACTA2 transcription and osteogenic differentiation. In conclusion we have found differences in responsiveness of SMC to Notch and to proosteogenic induction between BAV- and TAV-associated aortic aneurysms.

Genetics and Genomics of Congenital Heart Disease

Congenital heart disease is the most common birth defect, and because of major advances in medical and surgical management, there are now more adults living with congenital heart disease (CHD) than children. Until recently, the cause of the majority of CHD was unknown. Advances in genomic technologies have discovered the genetic causes of a significant fraction of CHD, while at the same time pointing to remarkable complexity in CHD genetics. This review will focus on the evidence for genetic causes underlying CHD and discuss data supporting both monogenic and complex genetic mechanisms underlying CHD. The discoveries from CHD genetic studies draw attention to biological pathways that simultaneously open the door to a better understanding of cardiac development and affect clinical care of patients with CHD. Finally, we address clinical genetic evaluation of patients and families affected by CHD.