0312: Characterization of human valvular interstitial cells isolated from normal and fibrocalcified aortic valves

PurposeAortic Valve Stenosis (AVS) affects 2% to 6% of population over 65 years in industrialized countries. This atherosclerosis-like pathology involves Valve Interstitial Cell (VIC) proliferation and commitment to osteoblast- like cells. This prevalent cell type of aortic valve presents five identifiable phenotypes: embryonic progenitor endothelial/mesenchymal cells, progenitor, quiescent, activated and osteoblastic VICs. To study the pathophysiology of AVS, their in vitro cultures are frequently used. Our purpose is to characterize VICs isolated from normal and fibrocalcified human aortic valves and analyze their in vitro behavior.MethodsWe collected 5 normal and 5 fibrocalcified human aortic valves. VICs were isolated by collagenase digestion. Characterization is assessed at different passages (2 to 5) by immunofluorescence. Analyzed markers consist of progenitor cell markers (SSEA4, ABCG2, CD90, NG2 and OsteoBlast CaDHerin (OB-CDH)), fibroblast markers (vimentin and HSP47) and smooth muscle cell (SMC) marker (α-actin). By blue trypan and MTS, we compared the viability and proliferation of VICs in standard and starvation medium at 48 hours.ResultsIndependently of their origin, VICs express all progenitor cell markers. Fibroblasts markers are expressed twice more by pathological VICs and four times more for SMC marker. In standard medium, VICs viability is similar (96,7±2,4% vs 96,4±2,3% ; normal vs pathological ± SEM). Pathological VICs proliferate more than normal VICs (2,2±0,7 vs 1,6±0,4 ; OD/OD control). In starvation medium, viability is significantly reduced for pathological VICs (89,6±7,9% vs 76,5±5,3%) but still proliferate in opposition with normal VICs (1,7±0,6 vs 1,2±0,3).ConclusionAll VICs phenotypes are found in vitro with no culture selection but in different ratios according to their origin. These new data in VICs isolated from normal or pathological human aortic valves allow us to approve their use in vitro

Assessment of the performance of hidden Markov models for imputation in animal breeding

Abstract Background In this paper, we review the performance of various hidden Markov model-based imputation methods in animal breeding populations. Traditionally, pedigree and heuristic-based imputation methods have been used for imputation in large animal populations due to their computational efficiency, scalability, and accuracy. Recent advances in the area of human genetics have increased the ability of probabilistic hidden Markov model methods to perform accurate phasing and imputation in large populations. These advances may enable these methods to be useful for routine use in large animal populations, particularly in populations where pedigree information is not readily available. Methods To test the performance of hidden Markov model-based imputation, we evaluated the accuracy and computational cost of several methods in a series of simulated populations and a real animal population without using a pedigree. First, we tested single-step (diploid) imputation, which performs both phasing and imputation. Second, we tested pre-phasing followed by haploid imputation. Overall, we used four available diploid imputation methods (fastPHASE, Beagle v4.0, IMPUTE2, and MaCH), three phasing methods, (SHAPEIT2, HAPI-UR, and Eagle2), and three haploid imputation methods (IMPUTE2, Beagle v4.1, and Minimac3). Results We found that performing pre-phasing and haploid imputation was faster and more accurate than diploid imputation. In particular, among all the methods tested, pre-phasing with Eagle2 or HAPI-UR and imputing with Minimac3 or IMPUTE2 gave the highest accuracies with both simulated and real data. Conclusions The results of this study suggest that hidden Markov model-based imputation algorithms are an accurate and computationally feasible approach for performing imputation without a pedigree when pre-phasing and haploid imputation are used. Of the algorithms tested, the combination of Eagle2 and Minimac3 gave the highest accuracy across the simulated and real datasets

A high resolution atlas of gene expression in the domestic sheep (Ovis aries)

Sheep are a key source of meat, milk and fibre for the global livestock sector, and an important biomedical model. Global analysis of gene expression across multiple tissues has aided genome annotation and supported functional annotation of mammalian genes. We present a large-scale RNA-Seq dataset representing all the major organ systems from adult sheep and from several juvenile, neonatal and prenatal developmental time points. The Ovis aries reference genome (Oar v3.1) includes 27,504 genes (20,921 protein coding), of which 25,350 (19,921 protein coding) had detectable expression in at least one tissue in the sheep gene expression atlas dataset. Network-based cluster analysis of this dataset grouped genes according to their expression pattern. The principle of 'guilt by association' was used to infer the function of uncharacterised genes from their co-expression with genes of known function. We describe the overall transcriptional signatures present in the sheep gene expression atlas and assign those signatures, where possible, to specific cell populations or pathways. The findings are related to innate immunity by focusing on clusters with an immune signature, and to the advantages of cross-breeding by examining the patterns of genes exhibiting the greatest expression differences between purebred and crossbred animals. This high-resolution gene expression atlas for sheep is, to our knowledge, the largest transcriptomic dataset from any livestock species to date. It provides a resource to improve the annotation of the current reference genome for sheep, presenting a model transcriptome for ruminants and insight into gene, cell and tissue function at multiple developmental stages

Valvular interstitial cell and aortic stenosis : impact of tissue factor pathway

Définie comme étant le rétrécissement de la valve, la sténose aortique (SA) est la 3ème pathologie cardiovasculaire dans les pays industrialisés. Touchant essentiellement les personnes âgées de plus de 65 ans, cette pathologie représente un véritable problème de santé publique compte tenu du vieillissement de la population. Considérée initialement comme issue d’un processus passif de dégénérescence, il est désormais établi que la sténose aortique est une pathologie dite « atherosclerosis-like » caractérisée par les processus d’inflammation, de fibrose, de néo-angiogenèse et de calcification. Certaines protéines de la voie de coagulation tel que le facteur tissulaire (FT) sont connues pour avoir un rôle pro-fibrotique et participent activement au développement des lésions athéroscléreuses. Leurs rôles dans la SA semblent donc probables et restent à être identifiés.Composante cellulaire majeure de la valve aortique, les VICs présentent 5 sous-populations distinctes : les cellules progénitrices embryonnaires (EPCs), les cellules progénitrices (pVICs), quiescentes (qVICs), activées (aVICs) et ostéoblastiques (obVICs). Au cours de la valvulogenèse, les EPCs permettent la cellularisation de la valve en se différenciant en qVIC. Celles-ci maintiennent l’homéostasie valvulaire et, en cas de lésion, s’activent (aVICs) pour réparer efficacement le tissu valvulaire. L’inflammation valvulaire et l’activation des VICs initient la sécrétion de protéines pro-calcifiantes induisant la différenciation des aVICs en obVICs. Enfin, les pVICs, naturellement présentes au sein de la valve (appelées résidantes) ou issues de la circulation sanguine (appelées hématopoïétiques), semblent favoriser le renouvellement cellulaire et peuvent être impliquées dans les processus angiogénique et ostéoblastique.Bien que décrites, la validation de la culture primaire des VICs par le suivi de ces sous-populations n’avait pas été réalisé et à constituer notre premier objectif. Nous avons ensuite étudié l’implication des voies de signalisation du FT dans le développement de la SA.Dans le cadre du suivi longitudinal des VICs depuis les valves aortiques humaines contrôles et pathologiques jusqu’à la culture in vitro réalisée sur plastique et sur collagène, nous avons tout d’abord montré que les différentes sous-populations étaient présentes au sein de ces valves avec des localisations et des proportions différentes selon l’état physiopathologique du tissu. Après digestion enzymatique de la valve, elles sont toutes retrouvées mais lors de la mise en culture, les pVICs hématopoïétiques ont disparu, quel que soit le support. Nous avons ainsi validé le modèle de culture primaire des VICs tout en mettant en lumière ses limites : absence des pVICs hématopoïétique, activation et différenciation ostéoblastique spontanée des VICs au cours de la culture.Dans le cadre de l’’étude de l’implication du FT dans le développement de la SA, nous avons montré sa colocalisation avec la thrombine et les calcifications de valves pathologiques. A partir de la culture primaire de VICs issues de valves humaines contrôles et pathologiques, nous avons montré que l’expression et l’activité du FT étaient constitutivement plus importantes pour les VICs pathologiques et que son expression pouvait être induite par l’IL1β. De plus, l’activation du FT, en présence de son ligand le facteur VII, induit, directement et via le récepteur PAR2, différentes voies de signalisation impliquées dans la prolifération cellulaire et les processus de fibrose et de calcification. Cette étude suggère ainsi que le FT produit par les VICs est un médiateur clef dans le développement de la sténose aortique.Defined as the narrowing of the aortic valve, aortic stenosis (AS) is the third cardiovascular pathology in industrialized countries. Affecting mainly people aged over 65 years, AS represents a major public health problem because of the aging of the population. After initially been considered as a passive degenerative process, it is now established that AS is an "atherosclerosis-like " disease characterized by the processes of inflammation, fibrosis, neo-angiogenesis and calcification. Some proteins of the coagulation pathway such as tissue factor (TF) are known to have a pro-fibrotic role and actively participate in the development of atherosclerotic lesions. Their implication in AS seems, therefore, probable and remain to be identified.Prevalent cellular component of the aortic valve, VICs have five distinct subpopulations: embryonic progenitor cells (EPCs), progenitor cells (pVICs) quiescent (qVICs), activated (aVICs) and osteoblastic (obVICs). During the valvulogenesis, EPCs allow the cellularization of the valve, differentiating into qVICs. These cells maintain the valvular homeostasis and, in case of damage, are activated (aVICs) to effectively repair the valve tissue. The valvular inflammation and VICs activation initiate the secretion of pro-calcifying proteins inducing the differentiation of aVICs into obVICs. Finally, pVICs, naturally present within the valve (called resident) or from the blood circulation (called hematopoietic), seem to promote cell renewal and may be involved in the angiogenic and osteoblastic processes.Although described, these subpopulations have never been studied longitudinally, in respect to their behavior in vitro. Our first objective was to perform this investigation. Our second objective was to study the potential role of TF pathway in the deleterious mechanisms of AS.As part of the longitudinal follow-up of VICs from control and pathological human aortic valves to the in vitro culture performed on plastic and collagen, we first showed that different subpopulations were present in these valves with different locations and proportions according to the pathophysiological state of the tissue. After enzymatic digestion, all subpopulations are found but, in culture, hematopoietic pVICs disappeared, whichever the support. Thus, we validated the primary culture model of VICs while highlighting its limitations: lack of hematopoietic pVICs, spontaneous osteoblastic differentiation and activation of VICs in culture.As part of the study the involvement of FT in the AS development, we showed its colocalization with thrombin and calcifications of pathological valves. We showed that the expression and activity of TF were constitutively more important in VICs from fibrocalcified valves than control ones and that IL-1β for pathological VICs and that its expression could be induced by IL1 beta. In addition, TF activation in the by its ligand FVII, induced, directly and via the PAR-2 receptor, different signaling pathways involved in cell proliferation and the processes of fibrosis and calcification. Thus, our findings suggest that the FT expressed by VICs mediates fibrocalcific processes of aortic stenosis

Cellule interstitielle de valve et sténose aortique : impact de la voie du facteur tissulaire

Defined as the narrowing of the aortic valve, aortic stenosis (AS) is the third cardiovascular pathology in industrialized countries. Affecting mainly people aged over 65 years, AS represents a major public health problem because of the aging of the population. After initially been considered as a passive degenerative process, it is now established that AS is an "atherosclerosis-like " disease characterized by the processes of inflammation, fibrosis, neo-angiogenesis and calcification. Some proteins of the coagulation pathway such as tissue factor (TF) are known to have a pro-fibrotic role and actively participate in the development of atherosclerotic lesions. Their implication in AS seems, therefore, probable and remain to be identified.Prevalent cellular component of the aortic valve, VICs have five distinct subpopulations: embryonic progenitor cells (EPCs), progenitor cells (pVICs) quiescent (qVICs), activated (aVICs) and osteoblastic (obVICs). During the valvulogenesis, EPCs allow the cellularization of the valve, differentiating into qVICs. These cells maintain the valvular homeostasis and, in case of damage, are activated (aVICs) to effectively repair the valve tissue. The valvular inflammation and VICs activation initiate the secretion of pro-calcifying proteins inducing the differentiation of aVICs into obVICs. Finally, pVICs, naturally present within the valve (called resident) or from the blood circulation (called hematopoietic), seem to promote cell renewal and may be involved in the angiogenic and osteoblastic processes.Although described, these subpopulations have never been studied longitudinally, in respect to their behavior in vitro. Our first objective was to perform this investigation. Our second objective was to study the potential role of TF pathway in the deleterious mechanisms of AS.As part of the longitudinal follow-up of VICs from control and pathological human aortic valves to the in vitro culture performed on plastic and collagen, we first showed that different subpopulations were present in these valves with different locations and proportions according to the pathophysiological state of the tissue. After enzymatic digestion, all subpopulations are found but, in culture, hematopoietic pVICs disappeared, whichever the support. Thus, we validated the primary culture model of VICs while highlighting its limitations: lack of hematopoietic pVICs, spontaneous osteoblastic differentiation and activation of VICs in culture.As part of the study the involvement of FT in the AS development, we showed its colocalization with thrombin and calcifications of pathological valves. We showed that the expression and activity of TF were constitutively more important in VICs from fibrocalcified valves than control ones and that IL-1β for pathological VICs and that its expression could be induced by IL1 beta. In addition, TF activation in the by its ligand FVII, induced, directly and via the PAR-2 receptor, different signaling pathways involved in cell proliferation and the processes of fibrosis and calcification. Thus, our findings suggest that the FT expressed by VICs mediates fibrocalcific processes of aortic stenosis.Définie comme étant le rétrécissement de la valve, la sténose aortique (SA) est la 3ème pathologie cardiovasculaire dans les pays industrialisés. Touchant essentiellement les personnes âgées de plus de 65 ans, cette pathologie représente un véritable problème de santé publique compte tenu du vieillissement de la population. Considérée initialement comme issue d’un processus passif de dégénérescence, il est désormais établi que la sténose aortique est une pathologie dite « atherosclerosis-like » caractérisée par les processus d’inflammation, de fibrose, de néo-angiogenèse et de calcification. Certaines protéines de la voie de coagulation tel que le facteur tissulaire (FT) sont connues pour avoir un rôle pro-fibrotique et participent activement au développement des lésions athéroscléreuses. Leurs rôles dans la SA semblent donc probables et restent à être identifiés.Composante cellulaire majeure de la valve aortique, les VICs présentent 5 sous-populations distinctes : les cellules progénitrices embryonnaires (EPCs), les cellules progénitrices (pVICs), quiescentes (qVICs), activées (aVICs) et ostéoblastiques (obVICs). Au cours de la valvulogenèse, les EPCs permettent la cellularisation de la valve en se différenciant en qVIC. Celles-ci maintiennent l’homéostasie valvulaire et, en cas de lésion, s’activent (aVICs) pour réparer efficacement le tissu valvulaire. L’inflammation valvulaire et l’activation des VICs initient la sécrétion de protéines pro-calcifiantes induisant la différenciation des aVICs en obVICs. Enfin, les pVICs, naturellement présentes au sein de la valve (appelées résidantes) ou issues de la circulation sanguine (appelées hématopoïétiques), semblent favoriser le renouvellement cellulaire et peuvent être impliquées dans les processus angiogénique et ostéoblastique.Bien que décrites, la validation de la culture primaire des VICs par le suivi de ces sous-populations n’avait pas été réalisé et à constituer notre premier objectif. Nous avons ensuite étudié l’implication des voies de signalisation du FT dans le développement de la SA.Dans le cadre du suivi longitudinal des VICs depuis les valves aortiques humaines contrôles et pathologiques jusqu’à la culture in vitro réalisée sur plastique et sur collagène, nous avons tout d’abord montré que les différentes sous-populations étaient présentes au sein de ces valves avec des localisations et des proportions différentes selon l’état physiopathologique du tissu. Après digestion enzymatique de la valve, elles sont toutes retrouvées mais lors de la mise en culture, les pVICs hématopoïétiques ont disparu, quel que soit le support. Nous avons ainsi validé le modèle de culture primaire des VICs tout en mettant en lumière ses limites : absence des pVICs hématopoïétique, activation et différenciation ostéoblastique spontanée des VICs au cours de la culture.Dans le cadre de l’’étude de l’implication du FT dans le développement de la SA, nous avons montré sa colocalisation avec la thrombine et les calcifications de valves pathologiques. A partir de la culture primaire de VICs issues de valves humaines contrôles et pathologiques, nous avons montré que l’expression et l’activité du FT étaient constitutivement plus importantes pour les VICs pathologiques et que son expression pouvait être induite par l’IL1β. De plus, l’activation du FT, en présence de son ligand le facteur VII, induit, directement et via le récepteur PAR2, différentes voies de signalisation impliquées dans la prolifération cellulaire et les processus de fibrose et de calcification. Cette étude suggère ainsi que le FT produit par les VICs est un médiateur clef dans le développement de la sténose aortique

Estimation of genetic and phenotypic parameters for ultrasound and carcass merit traits in crossbred beef cattle

Ultrasound measurements of 852 crossbred steers along with carcass merit measurements on 756 of them were used to examine their genetic and phenotypic parameters. Traits including ultrasound backfat thickness (UBF), ultrasound ribeye area (UREA), ultrasound marbling (UMAR), carcass weight (CWT), carcass grade fat (CGF), carcass average backfat thickness (CABF), carcass ribeye area (CREA), carcass marbling score (CMAR), and carcass lean meat yield (CLMY) were measured on 6 yr of residual feed intake trials from 2003 to 2008. Pairwise bivariate animal models were performed for each combination of traits using ASReml software to estimate heritability, phenotypic and genetic correlations among the traits. Significant fixed effects (contemporary group, and sire breed), covariates (age of dam, slaughter weight, and start test age of animal), and random additive effect were fitted in the models. The heritability estimates for UBF, UREA, UMAR, CWT, CGF, CABF, CREA, CMAR, and CLMY were 0.31, 0.17, 0.37, 0.40, 0.22, 0.25, 0.24, 0.38, and 0.28, respectively. Most of the phenotypic correlations were significant (