X Marks the Spot: The Profound Impact of Sex on Aortic Disease

Transcriptome analysis of the aortic coarctation area

Background

Coarctation of the aorta (CoA) is a relatively common congenital heart defect. The underlying causes are not known, but a combination of genetic factors and abnormalities linked to embryonic development is suspected. There are only a few studies of the underlying molecular mechanisms in CoA. The aim of the current study was to expand our understanding of the pathogenesis of CoA by characterizing the transcriptome of the coarctation area.

Methods

Tissue samples from 21 pediatric patients operated for CoA were dissected into separate biopsies consisting of the localized coarctation itself, proximal/distal tissue and ductus. RNA was sequenced to evaluate gene expression in the different biopsies.

Results

We observed an activation of acute phase response in samples from the localized coarctation compared to samples from distal or proximal tissue. However, we observed even bigger differences for patient age and sex than compared to biopsy location. A cluster of genes located at 1q21, including the S100 gene family, displayed contrasting expression depending on patient sex, and appeared to affect the balance between inflammatory and interferon pathways. Biopsies from patients <3 months old were characterized by a significantly higher fibrotic activity compared to samples from older patients. The ductus tissue was characterized by an upregulation of factors associated with proliferation.

Conclusions

The ongoing processes in the coarctation area are influenced by the age and sex of the patient, and possibly by differences in etiology between different patients. The impact of patient attributes must be taken into consideration when performing future studies.

Sex-related Outcomes After Thoracic Endovascular Repair for Intact Isolated Descending Thoracic Aortic Aneurysm: A Retrospective Cohort Study

OBJECTIVE

The aim of this study was to evaluate the association between sex and outcomes following thoracic endovascular aortic repair (TEVAR) for intact isolated descending thoracic aortic aneurysms (iiDTAA).

BACKGROUND

Data regarding sex-related long-term outcomes after TEVAR for iiDTAA are limited and conflicting results regarding perioperative outcomes have been reported.

METHODS

We included all TEVAR for iiDTAA between 2014 and 2019 in the Vascular Quality Initiative linked to Medicare claims, allowing reliable assessment of long-term outcome data. Primary outcomes included 5-year mortality, reinterventions, and ruptures of the thoracic aorta. Secondarily, we assessed perioperative outcomes.

RESULTS

We identified 685 patients, of which 54% were females. Females had higher aortic size index {females vs males: 3.31 [interquartile range (IQR), 2.81-3.85] cm/m 2 vs 2.93 (IQR, 2.42-3.36) cm/m 2 ; P <0.001}, were more frequently symptomatic (31% vs 20%; P =0.001), had longer procedure time [111 (IQR, 72-165) minutes vs 97 (IQR, 70-146) minutes] and more iliac procedures (16% vs 7.6%; P =0.001). Compared with males, females had similar rates of 5-year mortality [58% vs 53%; hazard ratio (HR), 0.93; 95% CI: 0.71-1.22; P =0.61), reinterventions (39% vs 30%; HR, 1.12; 95% CI: 0.73-1.73; P =0.60), and late ruptures (0.6% vs 1.2%; HR, 0.87; 95% CI: 0.12-6.18; P =0.89). After adjustment, these outcomes remained similar through 5 years. Furthermore, perioperative mortality was not significantly different between sexes (4.1% vs 2.2%; P =0.25), as were rates of any complication as a composite outcome (16% vs 21%; P =0.16), as well as of individual complications (all P >0.05).

CONCLUSION

Our findings suggest that females who undergo TEVAR for iiDTAA have similar 5-year and perioperative outcomes as compared with males.

Aortic Cellular Diversity and Quantitative Genome-Wide Association Study Trait Prioritization Through Single-Nuclear RNA Sequencing of the Aneurysmal Human Aorta

BACKGROUND

Mural cells in ascending aortic aneurysms undergo phenotypic changes that promote extracellular matrix destruction and structural weakening. To explore this biology, we analyzed the transcriptional features of thoracic aortic tissue.

METHODS

Single-nuclear RNA sequencing was performed on 13 samples from human donors, 6 with thoracic aortic aneurysm, and 7 without aneurysm. Individual transcriptomes were then clustered based on transcriptional profiles. Clusters were used for between-disease differential gene expression analyses, subcluster analysis, and analyzed for intersection with genetic aortic trait data.

RESULTS

We sequenced 71 689 nuclei from human thoracic aortas and identified 14 clusters, aligning with 11 cell types, predominantly vascular smooth muscle cells (VSMCs) consistent with aortic histology. With unbiased methodology, we found 7 vascular smooth muscle cell and 6 fibroblast subclusters. Differentially expressed genes analysis revealed a vascular smooth muscle cell group accounting for the majority of differential gene expression. Fibroblast populations in aneurysm exhibit distinct behavior with almost complete disappearance of quiescent fibroblasts. Differentially expressed genes were used to prioritize genes at aortic diameter and distensibility genome-wide association study loci highlighting the genes JUN, LTBP4 (latent transforming growth factor beta-binding protein 1), and IL34 (interleukin 34) in fibroblasts, ENTPD1, PDLIM5 (PDZ and LIM domain 5), ACTN4 (alpha-actinin-4), and GLRX in vascular smooth muscle cells, as well as LRP1 in macrophage populations.

CONCLUSIONS

Using nuclear RNA sequencing, we describe the cellular diversity of healthy and aneurysmal human ascending aorta. Sporadic aortic aneurysm is characterized by differential gene expression within known cellular classes rather than by the appearance of novel cellular forms. Single-nuclear RNA sequencing of aortic tissue can be used to prioritize genes at aortic trait loci.

Long-term outcomes in heritable thoracic aortic disease

Heritable aortic aneurysm is an increasingly recognized cause of morbidity and mortality. Whilst Marfan syndrome (MFS) is well-known, the clinical presentation and prognosis of more newly described genetic syndromes is less familiar to clinicians. There is a particular lack of knowledge regarding clinical outcomes for non-syndromal heritable aortic disease. This study investigated the presentation, clinical course and survival of patients with syndromal [Loeys-Dietz, aneurysm-osteoarthritis, and aneurysm-cerebral arteriopathy (ACTA2) syndrome] and non-syndromal heritable aortic disease in comparison to MFS. The study group includes 536 individuals (283 Marfan, 176 non-syndromal heritable aortopathy, 36 aneurysm-osteoarthritis, 32 Loeys-Dietz, and 9 ACTA2 aneurysm) enrolled in a longitudinal clinical follow-up between 1990 and 2022. Age at diagnosis differed between groups: Marfan = 22.0 ± 16.6; Loeys-Dietz = 29.6 ± 21.5; aneurysm-osteoarthritis = 36.4 ± 18.8; ACTA2 aneurysm = 43.4 ± 18.6; non-syndromal heritable aortopathy = 47.2 ± 16.6 years (p < 0.001). Aortic dissection was the presenting event in 8% individuals with Marfan compared to 27% with non-syndromal heritable aortopathy and 34% with Loeys-Dietz syndrome (p < 0.01). Mean follow-up duration for the group was 16.4 years (range 0.2–30 years) and 74 individuals died during follow-up (Marfan = 52, Loeys-Dietz = 6, aneurysm-osteoarthritis = 4, ACTA2 aneurysm = 1, heritable non-syndromal aortopathy = 11). At 10 years follow-up, actuarial mean survivals were: aneurysm-osteoarthritis = 77.5 ± 10.4%; Loeys-Dietz = 90.0 ± 6.8%; Marfan = 94.6 ± 1.4%; heritable non-syndromal aortopathy = 95.9 ± 2.1% (NS). There were 60 aortic dissections (24 Type A, 36 Type B) during follow-up. At 10 years, survival free of dissection was comparable between groups: aneurysm-osteoarthritis = 90.7 ± 6.4%; Loeys-Dietz = 94.4 ± 5.4%; Marfan = 96.1 ± 1.2%; heritable non-syndromal aortopathy = 93.9 ± 2.3%, with similar findings at 20 years. Prophylactic aortic surgery was a first event during follow-up for 196 individuals (ACTA2 aneurysm = 3; aneurysm-osteoarthritis = 10; Loeys-Dietz = 19; Marfan = 119; heritable non-syndromal aortopathy = 45). A second surgical intervention was required in 45 individuals and a third intervention in 21 individuals. At 10 years follow-up, survival free of surgery differed between groups: aneurysm-osteoarthritis = 68.5 ± 10.1%; Loeys-Dietz = 40.8 ± 11.2%; Marfan = 75.5 ± 2.7%; heritable non-syndromal aortopathy = 63.8 ± 4.7% (p < 0.001). At 20 years follow-up mean survival free of surgery was: aneurysm-osteoarthritis = 26.6 ± 14.7%; Loeys-Dietz = 9.1 ± 8.2%; Marfan = 57.2 ± 3.4%; heritable non-syndromal aortopathy = 41.6 ± 8.2% (p < 0.001). Diagnosis of newer syndromic and non-syndromal heritable aortopathies is delayed compared to MFS, with associated complications of presentation with aortic dissection. Survival of individuals enrolled in follow-up surveillance is comparable between different genetic aortopathies, however aortic dissections still occur and need for surgical intervention is high.

Dissecting the Heterogeneity of Human Thoracic Aortic Aneurysms Using Single-Cell Transcriptomics

Thoracic aortic aneurysm is a life-threatening condition caused by weakening of the thoracic aorta wall, often developing silently until dissection or rupture occurs. Despite substantial efforts in the past decade, there have been no significant therapeutic advances to prevent or clinically manage diverse forms of thoracic aortic aneurysm and dissection with the only effective treatment being surgical repair. There is an urgent need to understand intra- and inter-aneurysmal heterogeneity underlying thoracic aortic aneurysm and dissection pathogenesis. The human aortic wall consists of many cell types and exhibits significant regional heterogeneity. High-throughput single-cell RNA sequencing has emerged as the principal tool to reveal the complexity in human tissues and clinical specimens. Recent single-cell RNA sequencing studies of different aortic cell populations both in vivo and in vitro began to dissect this complexity and have provided valuable information. In this review, we summarize these findings and discuss the potential applications of single-cell transcriptomics and related high-content technologies in human thoracic aortic aneurysm and dissection research, as well as the challenges associated with it.

Genetic testing for aortopathies: primer for the nongeneticist

PURPOSE OF REVIEW

Although the majority of thoracic aortic aneurysms and dissections (TAD) in the overall population are mainly related to arterial hypertension and atherosclerosis, Heritable Thoracic Aortic Disease (HTAD) are increasingly recognized, especially in younger individuals. As fatal events in the setting of HTAD are preventable with timely detection and appropriate management, this review aims to provide an overview of the genetic basis of HTAD and practical recommendations for genetic evaluation in this setting.

RECENT FINDINGS

Thanks in part to a number of important efforts to set up (inter)national networks and consortia for collecting clinical and genetic data from patients with these rare disorders, significant progress has been made in understanding the natural evolution of these disorders. These insights are now starting to enable the development of recommendations for the management of these patients.In addition, pathogenic variants in a number of new genes have been identified in HTAD patients. On the basis of more extensive genetic screening in cohorts of patients with TAD, it is becoming clear that there is no strict boundary between syndromal and nonsyndromal HTAD entities. It is, therefore, important to at least consider genetic evaluation, not only for patients presenting with syndromic forms but also for more isolated TAD.Finally, there are indications that we will -- up to a certain point -- soon be able to draw up a more precise policy for individual patients, based on the underlying genetic defects SUMMARY: Genetic evaluation in (young) patients with both syndromic and nonsyndromic forms of HTAD should be considered and is helpful for the development of more precise medicine.