Clinical Interpretation of Genetic Variants in the Evaluation and Management of Thoracic Aortic Aneurysm and Dissection

BACKGROUND

We aimed to elucidate clinical implications of genetic variant interpretation in assessing disease severity and progression in thoracic aortic aneurysm and dissection (TAAD) patients.

METHODS

Consecutive TAAD patients with aortic root and/or ascending aortic aneurysms seen between 2011 and 2020 were included. Serial echocardiography, family history of TAAD, and management information were retrospectively collected and analyzed. Patients were classified into gene-positive (Gen-P), variants of uncertain significance, and gene-negative (Gen-N) groups.

RESULTS

A total of 407 patients were included: mean age 53.7±15.4 years, 64.4% women, and 38% with reported family history of TAAD. Thirty-seven (9.1%) were Gen-P; 147 (36.1%) had a variant of uncertain significance. Maximal aneurysm diameter was 4.78 mm larger in Gen-P than the other groups (P=.0003). In 162 unoperated TAAD patients with serial echocardiographic measurements, aneurysms enlarged at a significantly higher rate in the Gen-P (1.36 mm/year, 95% CI: 0.77-1.95) than variants of uncertain significance and Gen-N groups (0.83 mm/year vs 0.89 mm/year, respectively; P<.001). Aneurysms were 20% more likely to require surgical intervention for every millimeter increase in diameter. When considered on an individual basis, the highest growth rates were found in the variants of uncertain significance group.

CONCLUSION

While aneurysms linked to variants of uncertain significance demonstrate average growth rates comparable to those in Gen-N, close follow-up and genetic counseling in the variants of uncertain significance group are recommended for assessment of pathogenicity on a case-by-case basis. Early familial gene testing in TAAD is important to develop individualized preventive and therapeutic criteria.

Enhancer of zeste homolog 2 facilitates phenotypic transition of vascular smooth muscle cells leading to aortic aneurysm/dissection

Thoracic aortic aneurysms (TAAs) are a major cause of death owing to weaker blood vessel walls and higher rupture rates in affected individuals. Vascular smooth muscle cells (VSMCs) are the predominant cell type within the aortic wall and their dysregulation may contribute to TAA progression. Enhancer of zeste homolog 2 (EZH2), a histone methyltransferase, is involved in several pathological processes; however, the biological functions and mechanisms underlying VSMC phenotype transition and vascular intimal hyperplasia remain unclear. The present study aimed to determine the involvement of EZH2 in mediating VSMC function in the development of TAAs. The expression of EZH2 was revealed to be elevated in patients with thoracic aortic dissection and TAA mouse model through western blotting and reverse transcription-quantitative PCR experiments. Subsequently, a mouse model was established using β-aminopropionitrile. In vitro, EdU labeling, Transwell assay, wound healing assay and hematoxylin-eosin staining revealed that knocking down the Ezh2 gene could reduce the proliferation, invasion, migration, and calcification of mouse primary aortic smooth muscle cells. Flow cytometry analysis found that EZH2 deficiency increased cell apoptosis. Depletion of Ezh2 in mouse primary aortic VSMCs promoted the transformation of VSMCs from a synthetic to a contractile phenotype. Using RNA-sequencing analysis, it was demonstrated that Ezh2 regulated a group of genes, including integrin β3 (Itgb3), which are critically involved in the extracellular matrix signaling pathway. qChIP found Ezh2 occupies the Itgb3 promoter, thereby suppressing the expression of Itgb3. Ezh2 promotes the invasion and calcification of VSMCs, and this promoting effect is partially reversed by co-knocking down Itgb3. In conclusion, the present study identified a previously unrecognized EZH2-ITGB3 regulatory axis and thus provides novel mechanistic insights into the pathophysiological function of EZH2. EZH2 may thus serve as a potential target for the management of TAAs.

The key role of miRNA in syndromic and sporadic forms of ascending aortic aneurysms as biomarkers and targets of novel therapeutic strategies

Increasing evidence shows that epigenetics also plays a key role in regulating the pathogenetic mechanism of all types of aortic aneurysms. It is well-known that epigenetic factors modulate gene expression. This mechanism appears to be of interest especially knowing the relevance of genetic susceptibility and genetic factors in the complex pathophysiology of aortic aneurysms, and of sporadic forms; in fact, the latter are the result of a close interaction between genetic and modifiable lifestyle factors (i.e., nutrition, smoking, infections, use of drugs, alcohol, sedentary lifestyle, etc.). Epigenetic factors include DNA methylation, post-translational histone modifications, and non-coding RNA. Here, our attention is focused on the role of miRNA in syndromic and sporadic forms of thoracic aortic aneurysms. They could be both biomarkers and targets of novel therapeutic strategies.

miR-632 Induces DNAJB6 Inhibition Stimulating Endothelial-to-Mesenchymal Transition and Fibrosis in Marfan Syndrome Aortopathy

Marfan syndrome (MFS) is a connective tissue disorder caused by FBN1 gene mutations leading to TGF-β signaling hyperactivation, vascular wall weakness, and thoracic aortic aneurysms (TAAs). The pathogenetic mechanisms are not completely understood and patients undergo early vascular surgery to prevent TAA ruptures. We previously reported miR-632 upregulation in MFS TAA tissues compared with non-genetic TAA tissues. DNAJB6 is a gene target of miR-632 in cancer and plays a critical role in blocking epithelial-to-mesenchymal transition by inhibiting the Wnt/β catenin pathway. TGF-β signaling also activates Wnt/β catenin signaling and induces endothelial-to-mesenchymal transition (End-Mt) and fibrosis. We documented that miR-632 upregulation correlated with DNAJB6 expression in both the endothelium and the tunica media of MFS TAA (p < 0.01). Wnt/β catenin signaling, End-Mt, and fibrosis markers were also upregulated in MFS TAA tissues (p < 0.05, p < 0.01 and p < 0.001). Moreover, miR-632 overexpression inhibited DNAJB6, inducing Wnt/β catenin signaling, as well as End-Mt and fibrosis exacerbation (p < 0.05 and p < 0.01). TGF-β1 treatment also determined miR-632 upregulation (p < 0.01 and p < 0.001), with the consequent activation of the aforementioned processes. Our study provides new insights about the pathogenetic mechanisms in MFS aortopathy. Moreover, the high disease specificity of miR-632 and DNAJB6 suggests new potential prognostic factors and/or therapeutic targets in the progression of MFS aortopathy.

Structural genomic variants in thoracic aortic disease

PURPOSE OF REVIEW

Structural genomic variants have emerged as a relevant cause for several disorders, including intellectual disability, neuropsychiatric disorders, cancer and congenital heart disease. In this review, we will discuss the current knowledge about the involvement of structural genomic variants and, in particular, copy number variants in the development of thoracic aortic and aortic valve disease.

RECENT FINDINGS

There is a growing interest in the identification of structural variants in aortopathy. Copy number variants identified in thoracic aortic aneurysms and dissections, bicuspid aortic valve related aortopathy, Williams-Beuren syndrome and Turner syndrome are discussed in detail. Most recently, the first inversion disrupting FBN1 has been reported as a cause for Marfan syndrome.

SUMMARY

During the past 15 years, the knowledge on the role of copy number variants as a cause for aortopathy has grown significantly, which is partially due to the development of novel technologies including next-generation sequencing. Although copy number variants are now often investigated on a routine basis in diagnostic laboratories, more complex structural variants such as inversions, which require the use of whole genome sequencing, are still relatively new to the field of thoracic aortic and aortic valve disease.

Assessment of Pseudocoarctation of the Aorta with Saccular Aneurysms by Four-Dimensional Flow Magnetic Resonance Imaging and Histological Analysis

In this study, we present the case of a 21-year-old woman with pseudocoarctation of the aorta with saccular aneurysms that were evaluated by four-dimensional flow magnetic resonance imaging and histological analysis. We observed complete occupation of the aneurysm sacs by vortex flow and high peak wall shear stress in the proximal region of the kinked aorta. The aortic replacement was performed for the thoracic aortic aneurysms and the clinical course was uneventful. The aneurysms were histopathologically diagnosed as pseudoaneurysms based on the disappearance of all three layers and their replacement with collagen-rich connective tissues. These findings indicate that abnormal flow dynamics and the resulting abnormal shear stress in the aorta may play central roles in the formation and development of a saccular aneurysm.

Severe Tortuosity of the Distal Descending Thoracic Aorta Affects the Accuracy of Distal Deployment During a Thoracic Endovascular Aortic Repair

PURPOSE

An accurate distal deployment is essential for successful thoracic endovascular aortic repair (TEVAR) of a paradiaphragmatic aortic aneurysm. This study aimed to investigate the anatomical and intraoperative factors that affect the accuracy of distal deployment during TEVAR.

METHODS

We conducted a retrospective review of preoperative and postoperative computed tomography scans of 426 patients undergoing TEVAR at our institution between October 2008 and May 2021, of which the stent-graft was attempted to be deployed just above the celiac axis or the superior mesenteric artery in 56 patients. Based on the anatomical factors related to the malposition (deployed >10 mm away from the target vessel) and the greater curve to the straight-line ratio (G/S ratio), the patients were categorized as severe tortuosity (n=21) and mild tortuosity (n=35) groups to compare the operative and clinical outcomes.

RESULT

Stent-graft malpositioning occurred in 21 cases. Among all anatomical variables, only the G/S ratio was significantly larger in the malpositioned cases (p=0.049). A cutoff G/S ratio value of 1.15 was determined using the receiver operating curve analysis. In the severe tortuosity group, the distal end of the stent-graft was significantly farther (median: 10.0 [interquartile range (IQR): 2.5-19.5] mm vs 3.0 [0-8.0] mm; p=0.015) from the target vessel, and the tilt angle of the stent-graft's distal edge was larger (median: 21.4 [IQR: 15.8-24.5] vs 9.5 [5.5-12.5] degree; p<0.01) than that in the mild tortuosity group. Both groups were comparable for the incidence of a primary type Ib endoleak (p=0.454), a secondary type Ib endoleak (p=1.0), and the rate of distal reintervention (p=0.276).

CONCLUSION

Severe tortuosity in the distal descending thoracic aorta is associated with a malpositioned and tilted distal end of the stent-graft.

CLINICAL IMPACT

Thoracic endovascular aortic repair (TEVAR) for paradiaphragmatic thoracic aortic aneurysms requires accurate distal landing. In this paper, a retrospective CT analysis revealed that the greater curve to the straight-line ratio (G/S ratio) was associated to affects the malposition of the stent graft, defined as being deployed more than 10 mm away from the target vessel. Further, a comparative analysis based on the G/S ratio demonstrated that severe aortic tortuosity was associated with a more distal and tilted deployment of the stent graft.

Multi-Omics Profiling in Marfan Syndrome: Further Insights into the Molecular Mechanisms Involved in Aortic Disease

Thoracic aortic aneurysm is a potentially life-threatening disease with a strong genetic contribution. Despite identification of multiple genes involved in aneurysm formation, little is known about the specific underlying mechanisms that drive the pathological changes in the aortic wall. The aim of our study was to unravel the molecular mechanisms underlying aneurysm formation in Marfan syndrome (MFS). We collected aortic wall samples from FBN1 variant-positive MFS patients (n = 6) and healthy donor hearts (n = 5). Messenger RNA (mRNA) expression levels were measured by RNA sequencing and compared between MFS patients and controls, and between haploinsufficient (HI) and dominant negative (DN) FBN1 variants. Immunohistochemical staining, proteomics and cellular respiration experiments were used to confirm our findings. FBN1 mRNA expression levels were highly variable in MFS patients and did not significantly differ from controls. Moreover, we did not identify a distinctive TGF-β gene expression signature in MFS patients. On the contrary, differential gene and protein expression analysis, as well as vascular smooth muscle cell respiration measurements, pointed toward inflammation and mitochondrial dysfunction. Our findings confirm that inflammatory and mitochondrial pathways play important roles in the pathophysiological processes underlying MFS-related aortic disease, providing new therapeutic options.

Early Clinical Outcomes of Retrograde In-Situ Branched Stent Grafting for Complex Aortic Arch Aneurysms

OBJECTIVE

To evaluate the early outcomes of retrograde in-situ branched stent grafting (RIBS) using the gutter balloon technique for complex aortic arch aneurysms (CAAs).

METHODS

The RIBS technique is an in-situ needle fenestration procedure during thoracic endovascular aortic repair (TEVAR) with the reconstruction of cervical branches. The Double-RIBS (D-RIBS) for the reconstruction of the left common carotid artery and the brachiocephalic artery using the gutter balloon technique was performed in 30 high-risk patients. We describe the early clinical results of the D-RIBS technique for CAAs. Primary endpoints were technical success and 30-day mortality. Secondary endpoints were postoperative complications, rates of endoleaks, overall survival, aneurysm-related death, and re-interventions.

RESULTS

The mean age was 77.1±6.6 years and the mean maximum minor-axis aneurysmal diameter was 65.9±8.9 mm. Twenty six patients underwent D-RIBS for elective arch aortic aneurysm and four patients were for reintervention after Zone 2 TEVAR failure. Stent graft puncture was performed 60 times from the common carotid arteries and technical success was achieved in all cases (100%). Postoperative complications included cerebral infarction in 2 patients (6.7%), recurrent nerve palsy in one patient (3.3%). The 30-day mortality was 0%. During the median follow-up period of 14 months (6-56), overall survival at 12 months was 92.3% without any aneurysm-related death. Type 1b and type 2 endoleaks were observed in one each and no reintervention was encountered.

CONCLUSION

Early clinical outcomes of the D-RIBS for high-risk patients with CAAs are acceptable. The gutter balloon method enables safe and reliable fenestration. Further studies and dedicated devices are warranted.

Total aortic arch replacement using the thoraflex hybrid prosthesis: early- and medium-term results from a Scandinavian center

OBJECTIVE

The purpose of this study was to assess our early experience with the Thoraflex hybrid prosthesis. Design. This was a retrospective, single-center cohort study.

RESULTS

Between December 2014 and December 2019, 34 patients underwent total aortic arch replacement with the Thoraflex hybrid prosthesis. Fifteen of the patients had pre-operative chronic aortic dissection. The mean cardiopulmonary bypass time was 200 ± 35 min, aortic cross clamp time 114 ± 34 min, deep circulatory arrest time to the lower body 60 ± 22 min, and selective antegrade cerebral perfusion time 67 ± 24 min. The rate of stroke was 11.7% (4/34), paraparesis was 8.8% (3/34) and renal failure was 11.7% (4/34). No patient required permanent dialysis. Three (8.8%) patients died within the first 30 days postoperatively. All early deaths were due to stroke or spinal cord complications. During follow-up, an additional four patients died. Average follow-up was 32.4 ± 19.4 months (1102 patient-months) and was 100% complete. Survival at 12 months and 36 months was 88% ± 7.2% and 75% ± 12.7%, respectively.

CONCLUSIONS

The Thoraflex hybrid prosthesis can be used in the setting of total aortic arch replacement with good early- and medium-term results. Stroke and spinal cord complications remain an important source of early mortality.

Variants of the aortic arch in adult general population and their association with thoracic aortic aneurysm disease

BACKGROUND

Query a single institution computed tomography (CT) database to assess the prevalence of aortic arch anomalies in general adult population and their potential association with thoracic aortopathies.

METHODS

CT chest scan reports of patients aged 50-85 years old performed for any indication at a single health system between 2013 and 2016 were included in the analysis. Characteristics of patients with and without aortic arch anomalies were compared by t test and Fisher exact tests. Logistic regression analysis was performed to assess for independent risk factors of thoracic aortic aneurysm (TAA).

RESULTS

Of 21,336 CT scans, 603 (2.8%) described arch anomalies. Bovine arch (n = 354, 58.7%) was the most common diagnosis. Patients with arch anomalies were more likely to be female (p < .001), non-Caucasian(p < .001), and hypertensive (p < .001). Prevalence of TAA in arch anomalies group was 10.8% (n = 65) compared to 4.1% (n = 844) in the nonarch anomaly cohort (p < .001). The highest prevalence of thoracic aneurysm was associated with right-sided arch combined with aberrant left subclavian configuration (33%), followed by bovine arch (13%), and aberrant right subclavian artery (8.2%). On binary logistic regression, arch anomaly (OR = 2.85 [2.16-3.75]), aortic valve pathology (OR 2.93 [2.31-3.73]), male sex (OR 2.38 [2.01-2.80]), and hypertension (OR 1.47 [1.25-1.73]) were significantly associated with increased risk of thoracic aneurysm disease.

CONCLUSIONS

Reported prevalence of aortic arch anomalies by CT imaging in the older adult population is approximately 3%, with high association of TAA (OR = 2.85) incidence in this subgroup. This may warrant a more tailored surveillance strategy for aneurysm disease in this subpopulation.

[Gene mutation analysis of 19 Uighur families with aortic disease in Kashgar, China]

OBJECTIVE

To explore genetic mutation types and their correlation with clinical phenotypes in Uighur patients with aortic disease in Kashgar (Xinjiang Uighur Autonomous Region, China).

METHODS

We examined 37 pathogenic genes in 19 Uighur families with aortic diseases including Marfan syndrome from Kashgar using next generation sequencing, and the results were confirmed by Sanger sequence in the first relatives.

RESULTS

This study included 19 families with aortic diseases, in whom a total of 23 variants were identified, and 11 (57.89%) probands had one or more variants. Among them, definite pathogenic mutation was detected in one patient (5.26%), variants of uncertain significance (VUS) were found in 8 (42.11%), and benign/likely benign variants were detected in 7 (36.84%). The 23 variants identified included one (5.26%) pathogenic variant, 14 (60.87%) VUS, and 8 (34.78%) benign/likely benign variants. The 14 VUS were analyzed by prediction with SIFT and Polyphen2 HDIV, which identified 6 (42.86%) variants as deleterious/possibly damaging; all the 8 benign/likely benign variants were predicted to be deleterious/possibly damaging.

CONCLUSIONS

We detected 23 genetic variants in the 19 Uighur families with aortic diseases, and 22 of these variants remain to be verified by more patient data in future studies.

Synchronous and Metachronous Thoracic Aortic Aneurysms in Patients With Abdominal Aortic Aneurysms: A Systematic Review and Meta-Analysis

Background The prevalence of thoracic aortic aneurysms (TAA) in patients with known abdominal aortic aneurysms (AAA) is not well known and understudied. Our aim was to conduct a systematic review and meta-analysis of the overall prevalence of synchronous and metachronous TAA (SM-TAA) in patients with a known AAA and to understand the characteristics of this sub-population. Methods and Results We searched MEDLINE, EMBASE, and CENTRAL (Cochrane Central Register of Controlled Trials) from inception to November 2019 for all population-based studies reporting on the prevalence of SM-TAAs in a cohort of patients with AAA. Article screening and data extraction were performed by 2 authors and data were pooled using a random-effects model of proportions using Freeman-Tukey double arcsine transformation. The main outcome was the prevalence of SM-TAAs in patients with AAAs. Secondary outcomes were the prevalence of synchronous TAAs, metachronous TAAs, prevalence of TAAs in patients with AAA according to the anatomic location (ascending, arch, and descending) and the differences in prevalence of these aneurysms according to sex and risk factors. Six studies were included. The pooled-prevalence of SM-TAA in AAA patients was 19.2% (95% CI, 12.3-27.3). Results revealed that 15.2% (95% CI, 7.1-25.6) of men and 30.7% (95% CI, 25.2-36.5) of women with AAA had an SM-TAA. Women with AAA had a 2-fold increased risk of having an SM-TAA than men (relative risk [RRs], 2.16; 95% CI, 1.32-3.55). Diabetes mellitus was associated with a 43% decreased risk of having SM-TAA (RRs, 0.57; 95% CI, 0.41-0.80). Conclusions Since a fifth of AAA patients will have an SM-TAA, routine screening of SM-TAA and their clinical impact should be more thoroughly studied in patients with known AAA.

CD248+CD8+ T lymphocytes suppress pathological vascular remodeling in human thoracic aortic aneurysms

Aortic aneurysms are characterized by vascular inflammation, neovascularization, and extracellular matrix destruction of the aortic wall. Although experimental studies indicate a potential role of CD248 in microvessel remodeling, the functions of CD248 in human vascular pathologies remain unexplored. Here we aimed to study how CD248 interferes with pathological vascular remodeling of human aortic aneurysms. Immunofluorescent staining showed that CD248 expression was mainly localized in the CD8+ T cells infiltrating in the adventitia and media of aortic walls of patients with ascending thoracic aortic aneurysms. qPCR and immunofluorescent staining analyses revealed increased aortic CD248 expression and infiltrating CD248+CD8+ T cells in aortic aneurysms than in nonaneurysmal aortas. Flow cytometry analysis of human peripheral blood further identified a fraction of circulating CD248+ cells which was confined in the CD8+ T-cell compartment. The increased infiltrating of CD248+CD8+ T cells was coincident with reduced circulating CD248+CD8+ T cells in patients with ascending TAA when compared with patients with coronary artery diseases and healthy donors. The CD248+CD8+ T cells were characterized by upregulated IL-10 and downregulated IL-1β/INF-γ expression when compared with CD248-CD8+ T cells. Moreover, when co-cultured with human aortic endothelial cells, the CD248+CD8+ T cells not only downregulated endothelial expression of ICAM1/VCAM1 and MMP2/3 but also suppressed endothelial migration. This study shows that CD248 reduces pathological vascular remodeling via anti-inflammatory CD248+CD8+ T cells, revealing a CD248-mediated cellular mechanism against human aortic aneurysms.

One-Year Results From the SURPASS Observational Registry of the CTAG Stent-Graft With the Active Control System

Purpose: To report the outcomes from the observational SURPASS registry, which was created to assess the performance of the Conformable TAG (CTAG) stent-graft with the Active Control System (ACS) in patients undergoing thoracic endovascular aortic repair (TEVAR) in a real-world setting. Materials and Methods: The SURPASS registry (ClinicalTrials.gov; identifier NCT03286400) was an observational, prospective, single-arm, post-market, international study that enrolled patients undergoing TEVAR using the CTAG with ACS for both acute and chronic thoracic aortic disease between October 2017 and July 2018. The CTAG with ACS features 2-stage deployment of the stent-graft and an optional angulation mechanism that modifies only the proximal end of the stent-graft. During the observation period, 127 patients (mean age 67.1±12.1 years, range 27–86; 92 men) were enrolled and treated for an array of aortic pathologies, including chronic and acute lesions and 4 ruptured descending thoracic aneurysms. The primary outcome of this study was technical success; secondary outcomes were clinical success and major adverse events at 30 days and 12 months. The numbers of 2-stage device deployments and applications of the angulation mechanism were recorded, along with the reasons for use. Results: Technical success of the TEVAR was 97.6% owing to unintentional partial coverage of supra-aortic branches in 3 cases (the vessels were patent on imaging). The stent-graft was repositioned at its intermediate diameter in 79 patients (62.2%), and the angulation feature was applied in 64 cases (50.4%), mainly to improve proximal wall apposition and orthogonality in the aorta. The desired effect was achieved in 60 cases (93.8%). There was no device compression, bird-beak configuration, fracture, or graft occlusion. The 30-day and 12-month clinical success rates were 97.6% and 92.9%, respectively. There were 3 aorta-related deaths at 30 days and a further 3 at 12 months. Fatalities were due to a retrograde type A dissection (0.8%), paraplegia, bowel ischemia, sepsis in the setting of a mycotic aneurysm, aneurysm rupture post aortoesophageal fistula, and multiorgan dysfunction syndrome. Three endoleaks (2 type Ia and 1 type III) required reintervention. Conclusion: In the SURPASS registry, the use of the CTAG device with ACS showed promising outcomes despite the challenging pathologies. The new delivery system enables a controlled staged delivery with in situ adjustments during positioning, facilitating the treatment of complex aortic disease.

Network-based analysis reveals novel gene signatures in the peripheral blood of patients with sporadic nonsyndromic thoracic aortic aneurysm

Thoracic aortic aneurysm (TAA), a serious cardiovascular disease that causes morbidity and mortality worldwide. At present, few biomarkers can accurately diagnose the appearance of TAA before dissection or rupture. Our research has the intention to investigate the developing applicable biomarkers for TAA promising clinically diagnostic biomarkers or probable regulatory targets for TAA. In our research, we built correlation networks utilizing the expression profile of peripheral blood mononuclear cell obtained from a public microarray data set (GSE9106). Furthermore, we chose the turquoise module, which has the strongest significance with TAA and was further analyzed. Fourteen genes that overlapped with differentially expressed proteins in the medial aortic layer were obtained. Subsequently, we verified the results applying quantitative polymerase chain reaction (Q-PCR) to our clinical specimen. In general, the Q-PCR results coincide with the majority of the expression profile. Fascinatingly, a notable change occurred in CLU, DES, MYH10, and FBLN5. In summary, using weighted gene coexpression analysis, our study indicates that CLU, DES, MYH10, and FBLN5 were identified and validated to be related to TAA and might be candidate biomarkers or therapeutic targets for TAA.

Upregulation of lincRNA-p21 in thoracic aortic aneurysms is involved in the regulation of proliferation and apoptosis of vascular smooth muscle cells by activating TGF-β1 signaling pathway

OBJECTIVE

Long intergenic noncoding RNA-p21 (lincRNA-p21) has been proved in the pathogenesis of aortic aneurysms, while its functionality in thoracic aortic aneurysms (TAA) and the mechanism of function remains unclear. Therefore our study aimed to investigate the role of lincRNA-p21 in TAA.

METHODS

Aortic media specimens and blood samples were collected from both patients with TAA and healthy controls. Expression of lincRNA-p21 in those tissues was detected by reverse-transcription quantitative polymerase chain reaction (qRT-PCR). Diagnostic values of lincRNA-p21 in aortic media and blood for TAA were evaluated by receiver operating characteristic curve analysis. LincRNA-p21 overexpression human vascular smooth muscle cells (VSMCs) were prepared and the effects of lincRNA-p21 overexpression on cell proliferation and apoptosis were explored by cell counting kit-8 assay and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, respectively. Expression of lincRNA-p21 and transforming growth factor β1 (TGF-β1) in VSMCs with different treatment was detected by qRT-PCR and Western blot analysis, respectively.

RESULTS

Expression of lincRNA-p21 in aortic media tissues and blood was significantly upregulated in TAA patients than in healthy controls. Expression of lincRNA-p21 in aortic media and blood can be used to effectively distinguish TAA patients form healthy controls. LincRNA-p21 overexpression inhibited proliferation and promoted apoptosis of VSMCs, while TGF-β1 inhibitor reduced those effects. LincRNA-p21 overexpression upregulated TGF-β1 expression, while TGF-β1 activator showed no significant effects on lincRNA-p21 expression in VSMC.

CONCLUSION

LincRNA-p21 participates in TAA by regulating the proliferation and apoptosis of VSMCs through the activation of TGF-β1 signaling pathway.

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.

Vascular disease-causing mutation, smooth muscle α-actin R258C, dominantly suppresses functions of α-actin in human patient fibroblasts

The most common genetic alterations for familial thoracic aortic aneurysms and dissections (TAAD) are missense mutations in vascular smooth muscle (SM) α-actin encoded by ACTA2 We focus here on ACTA2-R258C, a recurrent mutation associated with early onset of TAAD and occlusive moyamoya-like cerebrovascular disease. Recent biochemical results with SM α-actin-R258C predicted that this variant will compromise multiple actin-dependent functions in intact cells and tissues, but a model system to measure R258C-induced effects was lacking. We describe the development of an approach to interrogate functional consequences of actin mutations in affected patient-derived cells. Primary dermal fibroblasts from R258C patients exhibited increased proliferative capacity compared with controls, consistent with inhibition of growth suppression attributed to SM α-actin. Telomerase-immortalized lines of control and R258C human dermal fibroblasts were established and SM α-actin expression induced with adenovirus encoding myocardin-related transcription factor A, a potent coactivator of ACTA2 Two-dimensional Western blotting confirmed induction of both wild-type and mutant SM α-actin in heterozygous ACTA2-R258C cells. Expression of mutant SM α-actin in heterozygous ACTA2-R258C fibroblasts abrogated the significant effects of SM α-actin induction on formation of stress fibers and focal adhesions, filamentous to soluble actin ratio, matrix contraction, and cell migration. These results demonstrate that R258C dominantly disrupts cytoskeletal functions attributed to SM α-actin in fibroblasts and are consistent with deficiencies in multiple cytoskeletal functions. Thus, cellular defects due to this ACTA2 mutation in both aortic smooth muscle cells and adventitial fibroblasts may contribute to development of TAAD and proliferative occlusive vascular disease.

The use of a new hybrid stentgraft for the repair of extensive thoracic aortic aneurysms with the frozen elephant trunk method - first Polish experiences

The frozen elephant trunk (FET) technique is a modification of the traditional elephant trunk method, which was introduced by Borst in 1983 in order to treat extensive thoracic aortic aneurysms. The crux of the new method is the different type of aortic prosthesis, consisting of a Dacron part (with or without branches leading to the arterial vessels which exit the aortic arch) and a port for extracorporeal circulation with a self-expanding nitinol stentgraft. This combination enables a complete one-stage treatment of the pathologies within the arch and the proximal segment of the descending aorta; moreover, it facilitates the performance of a two-stage hybrid treatment of extensive thoracic aortic aneurysms involving a significant part of the descending aorta. This article presents the cases of four patients with extensive aortic disease, who were implanted with Thoraflex prostheses (Vascutek, Scotland).

Vascular disease-causing mutation R258C in ACTA2 disrupts actin dynamics and interaction with myosin

Point mutations in vascular smooth muscle α-actin (SM α-actin), encoded by the gene ACTA2, are the most prevalent cause of familial thoracic aortic aneurysms and dissections (TAAD). Here, we provide the first molecular characterization, to our knowledge, of the effect of the R258C mutation in SM α-actin, expressed with the baculovirus system. Smooth muscles are unique in that force generation requires both interaction of stable actin filaments with myosin and polymerization of actin in the subcortical region. Both aspects of R258C function therefore need investigation. Total internal reflection fluorescence (TIRF) microscopy was used to quantify the growth of single actin filaments as a function of time. R258C filaments are less stable than WT and more susceptible to severing by cofilin. Smooth muscle tropomyosin offers little protection from cofilin cleavage, unlike its effect on WT actin. Unexpectedly, profilin binds tighter to the R258C monomer, which will increase the pool of globular actin (G-actin). In an in vitro motility assay, smooth muscle myosin moves R258C filaments more slowly than WT, and the slowing is exacerbated by smooth muscle tropomyosin. Under loaded conditions, small ensembles of myosin are unable to produce force on R258C actin-tropomyosin filaments, suggesting that tropomyosin occupies an inhibitory position on actin. Many of the observed defects cannot be explained by a direct interaction with the mutated residue, and thus the mutation allosterically affects multiple regions of the monomer. Our results align with the hypothesis that defective contractile function contributes to the pathogenesis of TAAD.

Endovascular treatment of descending thoracic aneurysms

INTRODUCTION

Current strategies for repair of descending thoracic aortic aneurysms consist of open repair with surgical graft replacement or thoracic endovascular aortic repair. We review and update our overall experience in aortic thoracic diseases and specifically analyzed our outcomes with thoracic endovascular aortic repair in patients with descending thoracic aortic aneurysms.

METHODS

From 1993 to present a total of 1144 patients were treated in our Center for pathology involving the thoracic aorta. Since 1998, 322 patients underwent thoracic endovascular aortic repair, and among this group, in 188 cases the descending aorta was involved. In 74% of patients treated for a descending thoracic aortic lesion, a degenerative aneurysm was observed.

RESULTS

In patients with descending thoracic aortic aneurysms receiving thoracic endovascular aortic repair, our technical success rate, i.e. deployment of endograft with complete exclusion of the lesion/minimal endoleak, was 99.5% (one case required emergent open conversion) with a perioperative mortality of 2.6% (five patients). The rate of spinal cord ischemia, manifesting either as paraplegia or paraparesis, was 4.7%. Delayed onset spinal cord ischemia ameliorated with adequate arterial pressure and cerebrospinal fluid drainage.

CONCLUSIONS

Our experience of selected patients undergoing thoracic endovascular aortic repair of descending thoracic aorta aneurysms is satisfactory with very low mortality and morbidity. A large use of thoracic endovascular aortic repair is foreseen in the next future.