Impact of sex and sex hormones on pathophysiology and progression of aortic stenosis in a murine model

The lesions observed in AS have been shown to be sex specific, with women presenting extensive fibrotic remodeling while men developing more calcification deposit. We thus aimed to evaluate the influence of sex and sex hormones on the pathophysiology of aortic valve stenosis (AS) in our mouse model of AS. LDLr-/- ApoB100/100 IGF-II+/- mice (n = 210) were separated in six different groups: (1) intact male (IM), (2) intact female (IF), (3) castrated male (CM), (4) ovariectomized females (OF), (5) CM with testosterone supplementation (CMT), and (6) OF with 17β-estradiol supplementation (OFE). Mice were fed a high-fat/high-sucrose/high-cholesterol diet for 6 months. Hemodynamic progression of AS was followed by transthoracic echocardiography (at 12 and 36 weeks) and analyzed in all mice alive at 36 weeks. Aortic valves were collected for histological and digital droplet PCR* analysis. Increases in peak velocity were comparable in IF and IM (24.2 ± 5.7 vs. 25.8 ± 5.3 cm/s; p = 0.68), but IF presented with less severe AS. Between the three groups of male mice, AS progression was more important in IM (increase in peak velocity: 24.2 ± 5.7 cm/s; p < 0.001) compared to CM (6.2 ± 1.4; p = 0.42), and CMT (15.1 ± 3.5; p = 0.002). In the three groups of female mice, there were no statistical differences in AS progression. Digital PCR analysis revealed an important upregulation of the osteogenic gene RunX2 in IM (p < 0.0001) and downregulation of the pro-calcifying gene ALPL in IF (p < 0.05). Male sex and testosterone play an important role in upregulation of pro-calcifying genes and hemodynamic progression of AS. However, female mice appeared to be protected against calcification, characterized by downregulation of pro-osteogenic genes, but presented a similar AS hemodynamic progressio

Les différences liées au sexe dans la physiopathologie de la sténose valvulaire aortique : impact du phénotype valvulaire, de l’âge, et des hormones sexuelles

La sténose valvulaire aortique (SVA) est une pathologie dégénérative de la valve aortique qui touche 2 à 4% de la population âgée de plus de 65 ans, et 4,6% des personnes âgées de plus de 75 ans. Cette pathologie se traduit par un épaississement et une rigidification des feuillets de la valve aortique, induisant un défaut d’ouverture et de fermeture de la valve. Parmi les nombreux facteurs de risque de développer une SVA, nous retrouvons la bicuspidie (anomalie congénitale touchant 1 à 2% de la population générale), l’âge, la dyslipidémie et le sexe mâle. Les mécanismes impliqués dans la physiopathologie de la SVA sont bien connus, nous retrouvons des mécanismes impliqués dans l’inflammation, la fibrose, la calcification, la survie et la prolifération cellulaire. Toutefois, malgré une littérature abondante sur la physiopathologique de la SVA, peu de recherches ont été effectuées sur l’impact du sexe et des hormones sexuelles sur la progression de la SVA. Il a été récemment observé que pour une même sévérité hémodynamique de la SVA, les hommes présentent un degré de calcification plus important et une proportion de fibrose valvulaire moins élevée comparativement aux femmes. Ainsi, l’objectif de cette maîtrise est d’étudier l’impact du sexe, du phénotype valvulaire et de l’âge sur le degré de calcification et le remodelage de la valve aortique chez des patients humains. Pour mener à bien ce projet, nous avions accès aux caractéristiques cliniques, aux données de tomodensitométrie, et aux valves explantées des patients. Les résultats obtenus montrent que les femmes, indépendamment du phénotype valvulaire ou de l’âge, vont présenter un degré de calcification plus faible et un remodelage fibrotique plus important des valves aortiques comparativement aux hommes. De plus, chez les patients bicuspides, les femmes jeunes présentent une valve aortique moins calcifiée que les femmes plus âgées.Aortic valve stenosis (AS) is a degenerative pathology of the aortic valve that affects 2 to 4% of the population over 65 years of age, and 4,6% of people over 75 years of age. This pathology results in a thickening and stiffening of the aortic valve leaflets, leading to an impaired opening, and closing of the valve. The risk factors for developing AS are bicuspid valve (a congenital anomaly affecting 1 to 2% of the general population), age, dyslipidemia, and male sex. The mechanisms involved in the pathophysiology of AS are relatively well known. Mechanisms involved in inflammation, fibrosis, calcification, survival, and cell proliferation are found. However, despite an important bibliography on the pathophysiology of AS, very little research has been done on the impact of sex and sex hormones on the progression of AS. It has recently been shown that for the same hemodynamic severity of AS, men have a higher degree of calcification and a lower proportion of fibrosis of their valve than women. Thus, the objective of this master is to study the impact of sex, valve phenotype and age on the degree of calcification and valve remodelling in human patients for whom we had their clinical characteristics as well as CTscan data and explanted valves. Results obtained shown that women, regardless of valve phenotype or age, will have a lower degree of valve calcification and a greater fibrotic remodelling of their valves than men. In addition, in bicuspid patients, young women have a less calcified aortic valve compared to older women

Age, sex and valve phenotype differences in fibro-calcific remodeling of calcified aortic valve

Background: In calcific aortic valve disease (CAVD) on tricuspid aortic valves (TAV), men have higher aortic valve calcification (AVC) and less fibrosis than women. However, little is known in bicuspid aortic valves (BAV). We thus aimed to investigate the impact of age, sex, and valve phenotype (TAV vs BAV) on fibro-calcific remodeling in CAVD. Methods and Results: We included 2 cohorts: 411 patients who underwent multidetector-computed-tomography (MDCT-cohort; 37% women) for AVC density assessment and 138 explanted aortic valves (histological-cohort; 50% women). The cohorts were divided in younger (YBAV: ˂60 years old) or older patients with BAV (OBAV: ≥60 years old), and TAV patients. In each group, women and men were matched. Women presented less AVC density than men in each groups of the MDCT-cohort (all p≤0.01). Moreover, in women, YBAV had the lowest AVC density (both p=0.02). In multivariate analysis, AVC density correlated with age (β-estimate±Standard-error: 6.5±1.8; p=0.0004), male sex (109.2±18.4; p<0.0001), and there was a trend with TAV (41.5±23.0; p=0.07). Women presented a higher collagen content than men (77.8±10.8 vs 69.9±12.9%; p<0.001) in the entire cohort. In women, YBAV had denser connective tissue than TAV and OBAV (both p≤0.05) while no difference was observed between men. Conclusions: In CAVD, women presented less calcification and more fibrotic remodeling than men, regardless of the phenotype of the valve or age of the patient. Moreover, younger women with bicuspid valves had less valve calcification. Thus, mineralization/fibrosis of the aortic valve is likely to have sex/age-specific-mechanisms and be influenced by the valve morphology

Sex-differences in echocardiographic assessment of aortic valve in young adult LDLr−/−/ApoB100/100/IGF-II+/− mice

Background LDLr−/−/ApoB100/100/IGF-II+/− mice are used as a calcific aortic valve disease (CAVD) model. However, normal aortic valve hemodynamics i.e. remotely from CAVD onset and the sex-related differences are poorly known. Methods and results Four groups of mice, intact males (IM, n = 49) and females (IF, n = 50), castrated males (CxM, n = 79) and ovariectomized females (OxF: 73), underwent a Doppler-echocardiography at 12 weeks of age. Gonadectomy was performed at 8 weeks. Aortic valve assessment using effective orifice area (EOA, using the continuity equation) and peak aortic transvalvular velocity (VPeak) was feasible in 89% of the mice with good to excellent reliability (intraclass correlation coefficients ranging from 0.90 to 0.98, p < 0.001). Mean VPeak was 104 ± 17 cm/s and mean EOA was 1.18*10−2 ± 0.22*10−2 cm2. EOA indexed to body surface area was 1.5 ± 0.3 cm2/m2. The 95th percentile of Vpeak was 132 cm/s and the 5th percentile of indexed EOA was 1.0 cm2/m2. Interestingly, IM had the highest VPeak (114 ± 14 cm/s) vs each of the other groups (CxM: 106 ± 19 cm/s, OxF: 97 ± 13 cm/s and IF: 96 ± 12 cm/s, ANOVA and corrected p < 0.001). This was mostly explained by a higher stroke volume (ANOVA and corrected p < 0.001) in IM compared to other groups. There were no major sex-differences in ventricular systolic function parameters. Conclusion In LDLr−/−/ApoB100/100/IGF-II CAVD mice model, an aortic EOA 132 cm/s may be proposed as thresholds to define CAVD. Intact male mice appear to have higher velocities