An endothelial regulatory module links blood pressure regulation with elite athletic performance.

The control of transcription is crucial for homeostasis in mammals. A previous selective sweep analysis of horse racing performance revealed a 19.6 kb candidate regulatory region 50 kb downstream of the Endothelin3 (EDN3) gene. Here, the region was narrowed to a 5.5 kb span of 14 SNVs, with elite and sub-elite haplotypes analyzed for association to racing performance, blood pressure and plasma levels of EDN3 in Coldblooded trotters and Standardbreds. Comparative analysis of human HiCap data identified the span as an enhancer cluster active in endothelial cells, interacting with genes relevant to blood pressure regulation. Coldblooded trotters with the sub-elite haplotype had significantly higher blood pressure compared to horses with the elite performing haplotype during exercise. Alleles within the elite haplotype were part of the standing variation in pre-domestication horses, and have risen in frequency during the era of breed development and selection. These results advance our understanding of the molecular genetics of athletic performance and vascular traits in both horses and humans.

Wall Shear Stress Measured with 4D Flow CMR Correlates with Biomarkers of Inflammation and Collagen Synthesis in Mild-to-Moderate Ascending Aortic Dilation and Tricuspid Aortic Valves.

AIMS: Understanding the mechanisms underlying ascending aortic dilation is imperative for refined risk stratification of these patients, particularly among incidentally identified patients, most commonly presenting with tricuspid valves. The aim of this study was to explore associations between ascending aortic hemodynamics, assessed using four-dimensional flow cardiovascular magnetic resonance imaging (4D Flow CMR), and circulating biomarkers in aortic dilation. METHODS AND RESULTS: Forty-seven cases with aortic dilation (diameter ≥40 mm) and 50 sex-and age-matched controls (diameter <40 mm), all with tricuspid aortic valves, underwent 4D flow CMR and venous blood sampling. Associations between flow displacement, wall shear stress (WSS), and oscillatory shear index in the ascending aorta derived from 4D Flow CMR, and biomarkers including interleukin-6, collagen type I α1 chain, metalloproteinases (MMPs), and inhibitors of MMPs derived from blood plasma, were investigated. Cases with dilation exhibited lower peak systolic WSS, higher flow displacement, and higher mean oscillatory shear index compared to controls without dilation. No significant differences in biomarkers were observed between the groups. Correlations between hemodynamics and biomarkers were observed, particularly between maximum time-averaged WSS and interleukin-6 (r = 0.539, p < 0.001), and maximum oscillatory shear index and collagen type I α1 chain (r = -0.575, p < 0.001 in cases). CONCLUSION: Significant associations were discovered between 4D flow CMR derived whole-cardiac cycle WSS and circulating biomarkers representing inflammation and collagen synthesis, suggesting an intricate interplay between hemodynamics and the processes of inflammation and collagen synthesis in patients with early aortic dilation and tricuspid aortic valves.

Predictive machine learning models for ascending aortic dilatation in patients with bicuspid and tricuspid aortic valves undergoing cardiothoracic surgery: a prospective, single-centre and observational study.

OBJECTIVES: The objective of this study was to develop clinical classifiers aiming to identify prevalent ascending aortic dilatation in patients with bicuspid aortic valve (BAV) and tricuspid aortic valve (TAV). DESIGN AND SETTING: A prospective, single-centre and observational cohort. PARTICIPANTS: The study involved 543 BAV and 491 TAV patients with aortic valve disease and/or ascending aortic dilatation, excluding those with coronary artery disease, undergoing cardiothoracic surgery at the Karolinska University Hospital (Sweden). MAIN OUTCOME MEASURES: Predictors of high risk of ascending aortic dilatation (defined as ascending aorta with a diameter above 40 mm) were identified through the application of machine learning algorithms and classic logistic regression models. EXPOSURES: Comprehensive multidimensional data, including valve morphology, clinical information, family history of cardiovascular diseases, prevalent diseases, demographic details, lifestyle factors, and medication. RESULTS: BAV patients, with an average age of 60.4±12.4 years, showed a higher frequency of aortic dilatation (45.3%) compared with TAV patients, who had an average age of 70.4±9.1 years (28.9% dilatation, p <0.001). Aneurysm prediction models for TAV patients exhibited mean area under the receiver-operating-characteristic curve (AUC) values above 0.8, with the absence of aortic stenosis being the primary predictor, followed by diabetes and high-sensitivity C reactive protein. Conversely, prediction models for BAV patients resulted in AUC values between 0.5 and 0.55, indicating low usefulness for predicting aortic dilatation. Classification results remained consistent across all machine learning algorithms and classic logistic regression models. CONCLUSION AND RECOMMENDATION: Cardiovascular risk profiles appear to be more predictive of aortopathy in TAV patients than in patients with BAV. This adds evidence to the fact that BAV-associated and TAV-associated aortopathy involves different pathways to aneurysm formation and highlights the need for specific aneurysm preventions in these patients. Further, our results highlight that machine learning approaches do not outperform classical prediction methods in addressing complex interactions and non-linear relations between variables.

A functional genomic framework to elucidate novel causal non-alcoholic fatty liver disease genes.

Background & Aims: Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver pathology in western countries, with serious public health consequences. Efforts to identify causal genes for NAFLD have been hampered by the relative paucity of human data from gold-standard magnetic resonance quantification of hepatic fat. To overcome insufficient sample size, genome-wide association studies using NAFLD surrogate phenotypes have been used, but only a small number of loci have been identified to date. In this study, we combined GWAS of NAFLD composite surrogate phenotypes with genetic colocalization studies followed by functional in vitro screens to identify bona fide causal genes for NAFLD. Approach & Results: We used the UK Biobank to explore the associations of our novel NAFLD score, and genetic colocalization to prioritize putative causal genes for in vitro validation. We created a functional genomic framework to study NAFLD genes in vitro using CRISPRi. Our data identify VKORC1, TNKS, LYPLAL1 and GPAM as regulators of lipid accumulation in hepatocytes and suggest the involvement of VKORC1 in the lipid storage related to the development of NAFLD. Conclusions: Complementary genetic and genomic approaches are useful for the identification of NAFLD genes. Our data supports VKORC1 as a bona fide NAFLD gene. We have established a functional genomic framework to study at scale putative novel NAFLD genes from human genetic association studies.

SPP1/osteopontin: a driver of fibrosis and inflammation in degenerative ascending aortic aneurysm?

Degenerative ascending aortic aneurysm (AscAA) is a silent and potentially fatal disease characterized by excessive vascular inflammation and fibrosis. We aimed to characterize the cellular and molecular signature for the fibrotic type of endothelial mesenchymal transition (EndMT) that has previously been described in degenerative AscAA. Patients undergoing elective open-heart surgery for AscAA and/or aortic valve repair were recruited. Gene expression in the intima-media of the ascending aorta was measured in 22 patients with non-dilated and 24 with dilated aortas, and candidate genes were identified. Protein expression was assessed using immunohistochemistry. Interacting distal gene enhancer regions were identified using targeted chromosome conformation capture (HiCap) in untreated and LPS-treated THP1 cells, and the associated transcription factors were analyzed. Differential expression analysis identified SPP1 (osteopontin) as a key gene in the signature of fibrotic EndMT in patients with degenerative AscAA. The aortic intima-media expression of SPP1 correlated with the expression of inflammatory markers, the level of macrophage infiltration, and the aortic diameter. HiCap analysis, followed by transcription factor binding analysis, identified ETS1 as a potential regulator of SPP1 expression under inflammatory conditions. In conclusion, the present findings suggest that SPP1 may be involved in the development of the degenerative type of AscAA. KEY MESSAGES: In the original manuscript titled "SPP1/osteopontin, a driver of fibrosis and inflammation in degenerative ascending aortic aneurysm?" by David Freiholtz, Otto Bergman, Saliendra Pradhananga, Karin Lång, Flore-Anne Poujade, Carl Granath, Christian Olsson, Anders Franco-Cereceda, Pelin Sahlén, Per Eriksson, and Hanna M Björck, we present novel findings on regulatory factors on osteopontin (SPP1) expression in immune cells involved in degenerative ascending aortic aneurysms (AscAA). The central findings convey: SPP1 is a potential driver of the fibrotic endothelial-to-mesenchymal transition in AscAA. SPP1/osteopontin expression in AscAA is predominately by immune cells. ETS1 is a regulatory transcription factor of SPP1 expression in AscAA immune cells.

Proteomic analysis of 92 circulating proteins and their effects in cardiometabolic diseases.

BACKGROUND: Human plasma contains a wide variety of circulating proteins. These proteins can be important clinical biomarkers in disease and also possible drug targets. Large scale genomics studies of circulating proteins can identify genetic variants that lead to relative protein abundance. METHODS: We conducted a meta-analysis on genome-wide association studies of autosomal chromosomes in 22,997 individuals of primarily European ancestry across 12 cohorts to identify protein quantitative trait loci (pQTL) for 92 cardiometabolic associated plasma proteins. RESULTS: We identified 503 (337 cis and 166 trans) conditionally independent pQTLs, including several novel variants not reported in the literature. We conducted a sex-stratified analysis and found that 118 (23.5%) of pQTLs demonstrated heterogeneity between sexes. The direction of effect was preserved but there were differences in effect size and significance. Additionally, we annotate trans-pQTLs with nearest genes and report plausible biological relationships. Using Mendelian randomization, we identified causal associations for 18 proteins across 19 phenotypes, of which 10 have additional genetic colocalization evidence. We highlight proteins associated with a constellation of cardiometabolic traits including angiopoietin-related protein 7 (ANGPTL7) and Semaphorin 3F (SEMA3F). CONCLUSION: Through large-scale analysis of protein quantitative trait loci, we provide a comprehensive overview of common variants associated with plasma proteins. We highlight possible biological relationships which may serve as a basis for further investigation into possible causal roles in cardiometabolic diseases.

Bicuspid aortic valve aortopathy is characterized by embryonic epithelial to mesenchymal transition and endothelial instability.

Bicuspid aortic valve (BAV) is the most common congenital heart malformation frequently associated with ascending aortic aneurysm (AscAA). Epithelial to mesenchymal transition (EMT) may play a role in BAV-associated AscAA. The aim of the study was to investigate the type of EMT associated with BAV aortopathy using patients with a tricuspid aortic valve (TAV) as a reference. The state of the endothelium was further evaluated. Aortic biopsies were taken from patients undergoing open-heart surgery. Aortic intima/media miRNA and gene expression was analyzed using Affymetrix human transcriptomic array. Histological staining assessed structure, localization, and protein expression. Migration/proliferation was assessed using ORIS migration assay. We show different EMT types associated with BAV and TAV AscAA. Specifically, in BAV-associated aortopathy, EMT genes related to endocardial cushion formation were enriched. Further, BAV vascular smooth muscle cells were less proliferative and migratory. In contrast, TAV aneurysmal aortas displayed a fibrotic EMT phenotype with medial degenerative insults. Further, non-dilated BAV aortas showed a lower miRNA-200c-associated endothelial basement membrane LAMC1 expression and lower CD31 expression, accompanied by increased endothelial permeability indicated by increased albumin infiltration. Embryonic EMT is a characteristic of BAV aortopathy, associated with endothelial instability and vascular permeability of the non-dilated aortic wall. KEY MESSAGES: Embryonic EMT is a feature of BAV-associated aortopathy. Endothelial integrity is compromised in BAV aortas prior to dilatation. Non-dilated BAV ascending aortas are more permeable than aortas of tricuspid aortic valve patients.

Acetylsalicylic Acid Is Associated With a Lower Prevalence of Ascending Aortic Aneurysm and a Decreased Aortic Expression of Cyclooxygenase 2.

Background Acetylsalicylic acid (ASA) therapy has been associated with a reduced prevalence and growth rate of abdominal as well as intracranial aneurysms, but the relationship between ASA and ascending aortic aneurysm formation remains largely unknown. The aim of the present study was to investigate whether ASA therapy is associated with a lower prevalence of ascending aortic aneurysm in a surgical cohort. Methods and Results One thousand seven hundred patients undergoing open-heart surgery for ascending aortic aneurysm and/or aortic valve disease were studied in this retrospective cross-sectional study. Aortic dilatation was defined as an aortic root or ascending aortic diameter ≥45 mm. Medications were self-reported by the patients in a systematic questionnaire. Cyclooxygenase gene expression was measured in the intima-media portion of the ascending aorta (n=117). In a multivariable analysis, ASA was associated with a reduced prevalence of ascending aortic aneurysm (relative risk, 0.68 [95% CI, 0.48-0.95], P=0.026) in patients with tricuspid aortic valves, but not in patients with bicuspid aortic valves (relative risk, 0.93 [95% CI, 0.64-1.34], P=0.687). Intima-media cyclooxygenase expression was positively correlated with ascending aortic dimensions (P<0.001 for cyclooxygenase-1 and P=0.05 for cyclooxygenase-2). In dilated, but not nondilated tricuspid aortic valve aortic specimens, ASA was associated with significantly lower cyclooxygenase-2 levels (P=0.034). Conclusions Our findings are consistent with the hypothesis that ASA treatment may attenuate ascending aortic aneurysmal growth, possibly via cyclooxygenase-2 inhibition in the ascending aortic wall and subsequent anti-inflammatory actions.

Sex Differences in Aortopathy and Valve Diseases Among Patients Undergoing Cardiac Surgical Procedure.

BACKGROUND: We aimed to study sex differences in aortopathy and valve disease among patients undergoing aortic valve replacement and/or surgical procedure for ascending aortic aneurysm and assess whether differences are specific for patients with bicuspid aortic valve (BAV) compared with patients with tricuspid aortic valve. METHODS: We used a single-center and observational cohort including 1045 patients undergoing elective open heart surgical procedure for aortic valve disease and/or ascending aortic aneurysm at the Karolinska Hospital (Stockholm, Sweden). RESULTS: Women (33.0%) were older than men (mean [SD]; 67.9 [11] years vs 62.5 [13] years for men; P < .001). No significant sex difference in prevalence of ascending aortic aneurysm was found according to absolute measures (P = .19); however, women had a greater dilation of the ascending aorta when normalized for body surface area (mean, 21.8 [SD, 6.3] mm/m2 vs 19.3 [SD, 4.4] mm/m2 for men; P < .001). Among the 560 patients with BAV, women had significantly more aortic stenosis (adjusted odds ratio, 2.23; 95% CI, 1.19-4.20; P = .013) and less aortic insufficiency (adjusted odds ratio, 0.42; 95% CI, 0.23-0.78; P < .01); whereas no sex difference was found among patients with tricuspid aortic valve. CONCLUSIONS: In this large study of patients undergoing cardiac surgical procedure, we found a greater degree of aortic dilation in women compared with men, suggesting a need for earlier monitoring of women. Moreover, women with BAV had a significantly higher prevalence of aortic stenosis compared with men. These results describe the aorta and valvular characteristics of patients by sex and provide guidance regarding which patients might benefit from closer surveillance.

Metformin therapy is not associated with the lower prevalence of ascending aortic aneurysm in diabetic patients.

OBJECTIVES: Metformin therapy has previously been associated with reduced abdominal aortic aneurysm growth rate in diabetic patients and shown to suppress the formation and progression of abdominal aortic aneurysm in normoglycemic mice. Here, we investigated the association between Metformin treatment and prevalence of aneurysm in the ascending aorta (AscAA). METHODS: A total of 734 patients undergoing open-heart surgery for AscAA and/or aortic valve disease were studied. Diabetes status and medication use were self-reported by the patients in a systematic questionnaire. Aortic dilatation was defined as an aortic root or ascending aortic diameter ≥4.0 cm. High-sensitivity C-reactive protein levels were assessed as a measure of systemic inflammation. RESULTS: We could confirm the inverse association between diabetes and AscAA prevalence (16% vs 43.9%, for diabetic and non-diabetic patients, respectively; Odds ratio 0.243; 95% CI, 0.129-0.460, P < 0.001). Furthermore, in diabetic patients, Metformin treatment was associated with lower high-sensitivity C-reactive protein levels. There was, however, no difference in the prevalence of AscAA among diabetic patients with and without Metformin treatment (16% vs 16% for treated and non-treated patients, respectively; OR 1.039; 95% CI 0.26-4.19, P = 0.957). CONCLUSIONS: Our data do not support a protective effect of Metformin therapy in AscAA formation. SUBJ COLLECTION: 161, 173.

Elevated Glucagon-like Peptide-1 and a Th2 Shift May Support Reduced Prevalence of Thoracic Aortic Aneurysm in Patients with Diabetes.

Glucagon-like peptide-1 (GLP-1) regulates processes involved in the pathophysiology of thoracic aortic aneurysms (TAAs), including inflammation, while protecting against aortic aneurysms in animal models. Type 2 diabetes (T2D) involves altered GLP-1 signaling due to pathology and/or therapy and is associated with reduced prevalence of TAAs. We aimed to assess whether T2D alters the inflammatory profile/proteolytic activity, possible correlations to elevated fasting GLP-1 (F-GLP-1), and its relevance for TAA. F-GLP-1, pro-inflammatory T helper 1 (Th1) cytokines, Th2 cytokines, C-reactive protein, and matrix metalloproteinase-2 activity (MMP-2) were analyzed in surgical patients with aortic valve pathology with/without T2D and without T2D but with TAA. Patients with T2D displayed an increase in the relative systemic expression of interleukin 6 and tumor necrosis factor α and a clear trend towards reduced levels of interferon γ (IFNγ). In addition, a positive association between GLP-1 and the plasma interleukin 4 (IL-4)/IFNγ ratio was detected. TAA was associated with significantly lower plasma levels of the Th2 cytokines IL-4 and interleukin 5. Plasma MMP-2 activity did not differ between groups. We conclude that T2D involved a Th2 shift, which associates with elevated F-GLP-1 and may-considering Th1 bias in TAA-contribute to reduced prevalence of TAA in T2D.

Valve disease and aortopathy associations of bicuspid aortic valve phenotypes differ between men and women.

OBJECTIVE: Determine whether associations between bicuspid aortic valve (BAV) phenotypes, valve disease and aortopathy differ between sexes. METHODS: 1045 patients with BAV (76.0% men, n=794) from two surgical centres were included in this cross-sectional study. Valve phenotype was classified intraoperatively as right-left (RL), right-non-coronary (RN), left-non-coronary (LN) or 2-sinus BAV. Echocardiography was used to determine type and degree of valve disease, and aortic dimensions. Aortic dilatation was defined as diameter ≥4.5 cm. RESULTS: RL was the most common phenotype (73.6%), followed by RN (16.2%), 2-sinus BAV (9.2%) and LN (1.1%), with no difference in phenotype distribution between men and women (p=0.634). Aortic valve insufficiency (AI) prevalence differed significantly with valve phenotype in men (p=0.047), with RL and LN having the highest prevalence (34.1% and 44.0%, respectively). In women, RN had a higher proportion of AI than RL (21.3% vs 7.3%, p=0.017). Men with RL had larger root dimensions, in particular at the sinus (mean difference 0.24 cm compared with RN, p=0.002). Men with 2-sinus BAV had the highest prevalence of root phenotype dilatation (7.0%, other phenotypes ≤2.3%, p=0.031), whereas women with 2-sinus BAV did not have root dilatation and smaller sinus dimensions (mean difference: 0.35 cm compared with RL, p=0.021). Aortic root segments were larger in men with AI compared with aortic stenosis (sinus mean difference: 0.40 cm, p<0.001). The difference was even larger in women (mean difference: 0.78 cm, p<0.001), and women with AI also had larger tubular segments (mean difference: 0.61 cm, p=0.001). CONCLUSIONS: There are significant sex differences in clinical associations of BAV phenotypes, which should be considered in further studies on the role of phenotypes in individualised patient management.

Syndecan-1 Expression Is Increased in the Aortic Wall of Patients with Type 2 Diabetes but Is Unrelated to Elevated Fasting Plasma Glucagon-Like Peptide-1.

A reduced prevalence of a thoracic aortic aneurysm (thoracic AA) is observed in type 2 diabetes (T2D). Glucagon-like peptide-1 (GLP-1)/GLP-1-based anti-diabetic therapy has indicated protective effects in thoracic AA and regulates the processes controlling the vascular tissue expression of Syndecan-1 (Sdc-1). Sdc-1 expression on macrophages infiltrating the aortic tissue contributes to a counter-regulatory response to thoracic AA formation in animal models through the interplay with inflammation/proteolytic activity. We hypothesized that elevated fasting plasma GLP-1 (fpGLP-1) increases the aortic Sdc-1 expression in T2D, which may contribute to a reduced prevalence of thoracic AA. Consequently, we determined whether T2D/thoracic AA associates with an altered Sdc-1 expression in the aortic tissue and the possible associations with fpGLP-1 and inflammation/proteolytic activity. From a cohort of surgical patients with an aortic valve pathology, we compared different disease groups (T2D/thoracic AA) with the same sub-cohort group of controls (patients without T2D and thoracic AA). The MMP-2 activity and Sdc-1, GLP-1R and CD68 expression were analyzed in the aortic tissue. GLP-1, Sdc-1 and cytokines were analyzed in the plasma. The aortic Sdc-1 expression was increased in T2D patients but did not correlate with fpGLP-1. Thoracic AA was associated with an increased aortic expression of Sdc-1 and the macrophage marker CD68. CD68 was not detected in T2D. In conclusion, an increased aortic Sdc-1 expression may contribute to a reduced prevalence of thoracic AA in T2D.

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.

Altered DNA methylation indicates an oscillatory flow mediated epithelial-to-mesenchymal transition signature in ascending aorta of patients with bicuspid aortic valve.

Disturbed flow has been suggested to contribute to aneurysm susceptibility in bicuspid aortic valve (BAV) patients. Lately, flow has emerged as an important modulator of DNA methylation. Hear we combined global methylation analysis with in vitro studies of flow-sensitive methylation to identify biological processes associated with BAV-aortopathy and the potential contribution of flow. Biopsies from non-dilated and dilated ascending aortas were collected from BAV (n = 21) and tricuspid aortic valve (TAV) patients (n = 23). DNA methylation and gene expression was measured in aortic intima-media tissue samples, and in EA.hy926 and primary aortic endothelial cells (ECs) isolated from BAV and TAV exposed to oscillatory (±12 dynes/cm2) or laminar (12 dynes/cm2) flow. We show methylation changes related to epithelial-mesenchymal-transition (EMT) in the non-dilated BAV aorta, associated with oscillatory flow related to endocytosis. The results indicate that the flow-response in BAV ECs involves hypomethylation and increased expression of WNT/ß-catenin genes, as opposed to an angiogenic profile in TAV ECs. The EMT-signature was exasperated in dilated BAV aortas. Aberrant EMT in BAV aortic walls could contribute to increased aneurysm susceptibility, and may be due to disturbed flow-exposure. Perturbations during the spatiotemporally related embryonic development of ascending aorta and semilunar valves can however not be excluded.

Corrigendum: Candidate Gene Resequencing in a Large Bicuspid Aortic Valve-Associated Thoracic Aortic Aneurysm Cohort: SMAD6 as an Important Contributor.

[This corrects the article on p. 400 in vol. 8, PMID: 28659821.].

Identification of a novel proinsulin-associated SNP and demonstration that proinsulin is unlikely to be a causal factor in subclinical vascular remodelling using Mendelian randomisation.

BACKGROUND AND AIMS: Increased proinsulin relative to insulin levels have been associated with subclinical atherosclerosis (measured by carotid intima-media thickness (cIMT)) and are predictive of future cardiovascular disease (CVD), independently of established risk factors. The mechanisms linking proinsulin to atherosclerosis and CVD are unclear. A genome-wide meta-analysis has identified nine loci associated with circulating proinsulin levels. Using proinsulin-associated SNPs, we set out to use a Mendelian randomisation approach to test the hypothesis that proinsulin plays a causal role in subclinical vascular remodelling. METHODS: We studied the high CVD-risk IMPROVE cohort (n = 3345), which has detailed biochemical phenotyping and repeated, state-of-the-art, high-resolution carotid ultrasound examinations. Genotyping was performed using Illumina Cardio-Metabo and Immuno arrays, which include reported proinsulin-associated loci. Participants with type 2 diabetes (n = 904) were omitted from the analysis. Linear regression was used to identify proinsulin-associated genetic variants. RESULTS: We identified a proinsulin locus on chromosome 15 (rs8029765) and replicated it in data from 20,003 additional individuals. An 11-SNP score, including the previously identified and the chromosome 15 proinsulin-associated loci, was significantly and negatively associated with baseline IMTmean and IMTmax (the primary cIMT phenotypes) but not with progression measures. However, MR-Eggers refuted any significant effect of the proinsulin-associated 11-SNP score, and a non-pleiotropic SNP score of three variants (including rs8029765) demonstrated no effect on baseline or progression cIMT measures. CONCLUSIONS: We identified a novel proinsulin-associated locus and demonstrated that whilst proinsulin levels are associated with cIMT measures, proinsulin per se is unlikely to have a causative effect on cIMT.

Candidate Gene Resequencing in a Large Bicuspid Aortic Valve-Associated Thoracic Aortic Aneurysm Cohort: SMAD6 as an Important Contributor.

Bicuspid aortic valve (BAV) is the most common congenital heart defect. Although many BAV patients remain asymptomatic, at least 20% develop thoracic aortic aneurysm (TAA). Historically, BAV-related TAA was considered as a hemodynamic consequence of the valve defect. Multiple lines of evidence currently suggest that genetic determinants contribute to the pathogenesis of both BAV and TAA in affected individuals. Despite high heritability, only very few genes have been linked to BAV or BAV/TAA, such as NOTCH1, SMAD6, and MAT2A. Moreover, they only explain a minority of patients. Other candidate genes have been suggested based on the presence of BAV in knockout mouse models (e.g., GATA5, NOS3) or in syndromic (e.g., TGFBR1/2, TGFB2/3) or non-syndromic (e.g., ACTA2) TAA forms. We hypothesized that rare genetic variants in these genes may be enriched in patients presenting with both BAV and TAA. We performed targeted resequencing of 22 candidate genes using Haloplex target enrichment in a strictly defined BAV/TAA cohort (n = 441; BAV in addition to an aortic root or ascendens diameter ≥ 4.0 cm in adults, or a Z-score ≥ 3 in children) and in a collection of healthy controls with normal echocardiographic evaluation (n = 183). After additional burden analysis against the Exome Aggregation Consortium database, the strongest candidate susceptibility gene was SMAD6 (p = 0.002), with 2.5% (n = 11) of BAV/TAA patients harboring causal variants, including two nonsense, one in-frame deletion and two frameshift mutations. All six missense mutations were located in the functionally important MH1 and MH2 domains. In conclusion, we report a significant contribution of SMAD6 mutations to the etiology of the BAV/TAA phenotype.

Mesenchymal state of intimal cells may explain higher propensity to ascending aortic aneurysm in bicuspid aortic valves.

Individuals with a bicuspid aortic valve (BAV) are at significantly higher risk of developing aortic complications than individuals with tricuspid aortic valves (TAV) and defective signaling during the embryonic development and/or life time exposure to abnormal hemodynamic have been proposed as underlying factors. However, an explanation for the molecular mechanisms of aortopathy in BAV has not yet been provided. We combined proteomics, RNA analyses, immunohistochemistry, and electron microscopy to identify molecular differences in samples of non-dilated ascending aortas from BAV (N = 62) and TAV (N = 54) patients. Proteomic analysis was also performed for dilated aortas (N = 6 BAV and N = 5 TAV) to gain further insight into the aortopathy of BAV. Our results collectively showed the molecular signature of an endothelial/epithelial-mesenchymal (EndMT/EMT) transition-like process, associated with instability of intimal cell junctions and activation of RHOA pathway in the intima and media layers of ascending aorta in BAV patients. We propose that an improper regulation of EndMT/EMT during the spatiotemporally related embryogenesis of semilunar valves and ascending aorta in BAV individuals may result in aortic immaturity and instability prior to dilation. Exasperation of EndMT/EMT state in post embryonic life and/or exposure to non-physiological hemodynamic could lead to the aneurysm of ascending aorta in BAV individuals.

Genetic loci on chromosome 5 are associated with circulating levels of interleukin-5 and eosinophil count in a European population with high risk for cardiovascular disease.

IL-5 is a Th2 cytokine which activates eosinophils and is suggested to have an atheroprotective role. Genetic variants in the IL5 locus have been associated with increased risk of CAD and ischemic stroke. In this study we aimed to identify genetic variants associated with IL-5 concentrations and apply a Mendelian randomisation approach to assess IL-5 levels for causal effect on intima-media thickness in a European population at high risk of coronary artery disease. We analysed SNPs within robustly associated candidate loci for immune, inflammatory, metabolic and cardiovascular traits. We identified 2 genetic loci for IL-5 levels (chromosome 5, rs56183820, BETA=0.11, P=6.73E(-5) and chromosome 14, rs4902762, BETA=0.12, P=5.76E(-6)) and one for eosinophil count (rs72797327, BETA=-0.10, P=1.41E(-6)). Both chromosome 5 loci were in the vicinity of the IL5 gene, however the association with IL-5 levels failed to replicate in a meta-analysis of 2 independent cohorts (rs56183820, BETA=0.04, P=0.2763, I(2)=24, I(2)-P=0.2516). No significant associations were observed between SNPs associated with IL-5 levels or eosinophil count and IMT measures. Expression quantitative trait analyses indicate effects of the IL-5 and eosinophil-associated SNPs on RAD50 mRNA expression levels (rs12652920 (r2=0.93 with rs56183820) BETA=-0.10, P=8.64E(-6) and rs11739623 (r2=0.96 with rs72797327) BETA=-0.23, P=1.74E(-29), respectively). Our data do not support a role for IL-5 levels and eosinophil count in intima-media thickness, however SNPs associated with IL-5 and eosinophils might influence stability of the atherosclerotic plaque via modulation of RAD50 levels.