RESUMEN
The sole effective treatment for most patients with heart valve disease is valve replacement by implantation of mechanical or biological prostheses. However, mechanical valves represent high risk of thromboembolism, and biological prostheses are prone to early degeneration. In this work, we aim to determine the potential of novel environmentally-friendly non-isocyanate polyurethanes (NIPUs) for manufacturing synthetic prosthetic heart valves. Polyhydroxyurethane (PHU) NIPUs are synthesized via an isocyanate-free route, tested in vitro, and used to produce aortic valves. PHU elastomers reinforced with a polyester mesh show mechanical properties similar to native valve leaflets. These NIPUs do not cause hemolysis. Interestingly, both platelet adhesion and contact activation-induced coagulation are strongly reduced on NIPU surfaces, indicating low thrombogenicity. Fibroblasts and endothelial cells maintain normal growth and shape after indirect contact with NIPUs. Fluid-structure interaction (FSI) allows modeling of the ideal valve design, with minimal shear stress on the leaflets. Injection-molded valves are tested in a pulse duplicator and show ISO-compliant hydrodynamic performance, comparable to clinically-used bioprostheses. Poly(tetrahydrofuran) (PTHF)-NIPU patches do not show any evidence of calcification over a period of 8 weeks. NIPUs are promising sustainable biomaterials for the manufacturing of improved prosthetic valves with low thrombogenicity.
Asunto(s)
Prótesis Valvulares Cardíacas , Poliuretanos , Humanos , Poliuretanos/química , Isocianatos , Células Endoteliales , Válvula Aórtica/cirugíaRESUMEN
Aims: Dietary cholesterol and palmitic acid are risk factors for cardiovascular diseases (CVDs) affecting the arteries and the heart valves. The ionizing radiation that is frequently used as an anticancer treatment promotes CVD. The specific pathophysiology of these distinct disease manifestations is poorly understood. We, therefore, studied the biological effects of these dietary lipids and their cardiac irradiation on the arteries and the heart valves in the rabbit models of CVD. Methods and Results: Cholesterol-enriched diet led to the thickening of the aortic wall and the aortic valve leaflets, immune cell infiltration in the aorta, mitral and aortic valves, as well as aortic valve calcification. Numerous cells expressing α-smooth muscle actin were detected in both the mitral and aortic valves. Lard-enriched diet induced massive aorta and aortic valve calcification, with no detectable immune cell infiltration. The addition of cardiac irradiation to the cholesterol diet yielded more calcification and more immune cell infiltrates in the atheroma and the aortic valve than cholesterol alone. RNA sequencing (RNAseq) analyses of aorta and heart valves revealed that a cholesterol-enriched diet mainly triggered inflammation-related biological processes in the aorta, aortic and mitral valves, which was further enhanced by cardiac irradiation. Lard-enriched diet rather affected calcification- and muscle-related processes in the aorta and aortic valve, respectively. Neutrophil count and systemic levels of platelet factor 4 and ent-8-iso-15(S)-PGF2α were identified as early biomarkers of cholesterol-induced tissue alterations, while cardiac irradiation resulted in elevated levels of circulating nucleosomes. Conclusion: Dietary cholesterol, palmitic acid, and cardiac irradiation combined with a cholesterol-rich diet led to the development of distinct vascular and valvular lesions and changes in the circulating biomarkers. Hence, our study highlights unprecedented specificities related to common risk factors that underlie CVD.
RESUMEN
Several clinical reports indicate that the use of amphetaminic anorectic drugs or ergot derivatives could cause valvular heart disease (VHD). We sought to investigate whether valvular lesions develop in response to long-term oral administration of these drugs and to identify drug-targeted biological processes that may lead to VHD. Treatment of New Zealand White rabbits with pergolide, dexfenfluramine, or high-dose serotonin for 16 weeks induced valvular alterations characterized by extracellular matrix remodeling. Transcriptome profiling of tricuspid valves using RNA sequencing revealed distinct patterns of differentially expressed genes (DEGs) that clustered according to the different treatments. Genes that were affected by the three treatments were functionally enriched for reduced cell metabolism processes. The two drugs yielded more changes in gene expression than serotonin and shared most of the DEGs. These DEGs were mostly enriched for decreased biosynthetic processes, increased cell-matrix interaction, and cell response to growth factors, including TGF-ß, which was associated with p38 MAPK activation. Treatment with pergolide specifically affected genes involved in homeostasis, which was corroborated by the activation of the master regulator of cell energy homeostasis, AMPK-α, as well as decreased levels of metabolism-related miR-107. Thus, both pergolide and dexfenfluramine may cause VHD through valve metabolic reprogramming and matrix remodeling.
Asunto(s)
Dexfenfluramina/efectos adversos , Matriz Extracelular/efectos de los fármacos , Regulación de la Expresión Génica/efectos de los fármacos , Enfermedades de las Válvulas Cardíacas/inducido químicamente , Pergolida/efectos adversos , Válvula Tricúspide/efectos de los fármacos , Proteínas Quinasas Activadas por AMP/metabolismo , Administración Oral , Animales , Proliferación Celular , Análisis por Conglomerados , Activación Enzimática , Femenino , Enfermedades de las Válvulas Cardíacas/metabolismo , Enfermedades de las Válvulas Cardíacas/patología , Homeostasis , MicroARNs/genética , Conejos , Análisis de Secuencia de ARN , Serotonina/efectos adversos , Transcriptoma , Factor de Crecimiento Transformador beta/metabolismo , Válvula Tricúspide/metabolismo , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismoRESUMEN
BACKGROUND: Myxomatous valve degeneration (MVD) involves the progressive thickening and degeneration of the heart valves, leading to valve prolapse, regurgitant blood flow, and impaired cardiac function. Leukocytes composed primarily of macrophages have recently been detected in myxomatous valves, but the timing of the presence and the contributions of these cells in MVD progression are not known. METHODS: We examined MVD progression, macrophages, and the valve microenvironment in the context of Marfan syndrome (MFS) using mitral valves from MFS mice (Fbn1C1039G/+), gene-edited MFS pigs (FBN1Glu433AsnfsX98/+), and patients with MFS. Additional histological and transcriptomic evaluation was performed by using nonsyndromic human and canine myxomatous valves, respectively. Macrophage ontogeny was determined using MFS mice transplanted with mTomato+ bone marrow or MFS mice harboring RFP (red fluorescent protein)-tagged C-C chemokine receptor type 2 (CCR2) monocytes. Mice deficient in recruited macrophages (Fbn1C1039G/+;Ccr2RFP/RFP) were generated to determine the requirements of recruited macrophages to MVD progression. RESULTS: MFS mice recapitulated histopathological features of myxomatous valve disease by 2 months of age, including mitral valve thickening, increased leaflet cellularity, and extracellular matrix abnormalities characterized by proteoglycan accumulation and collagen fragmentation. Diseased mitral valves of MFS mice concurrently exhibited a marked increase of infiltrating (MHCII+, CCR2+) and resident macrophages (CD206+, CCR2-), along with increased chemokine activity and inflammatory extracellular matrix modification. Likewise, mitral valve specimens obtained from gene-edited MFS pigs and human patients with MFS exhibited increased monocytes and macrophages (CD14+, CD64+, CD68+, CD163+) detected by immunofluorescence. In addition, comparative transcriptomic evaluation of both genetic (MFS mice) and acquired forms of MVD (humans and dogs) unveiled a shared upregulated inflammatory response in diseased valves. Remarkably, the deficiency of monocytes was protective against MVD progression, resulting in a significant reduction of MHCII macrophages, minimal leaflet thickening, and preserved mitral valve integrity. CONCLUSIONS: All together, our results suggest sterile inflammation as a novel paradigm to disease progression, and we identify, for the first time, monocytes as a viable candidate for targeted therapy in MVD.
Asunto(s)
Enfermedades de las Válvulas Cardíacas/patología , Síndrome de Marfan/patología , Monocitos/metabolismo , Animales , Quimiocina CCL2/metabolismo , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Perros , Matriz Extracelular/metabolismo , Fibrilina-1/genética , Fibrilina-1/metabolismo , Enfermedades de las Válvulas Cardíacas/complicaciones , Enfermedades de las Válvulas Cardíacas/metabolismo , Antígenos Comunes de Leucocito/metabolismo , Macrófagos/citología , Macrófagos/metabolismo , Síndrome de Marfan/complicaciones , Síndrome de Marfan/metabolismo , Ratones , Ratones Endogámicos C57BL , Válvula Mitral/metabolismo , Válvula Mitral/fisiopatología , Monocitos/citología , PorcinosRESUMEN
The mitral valve is a complex multilayered structure populated by fibroblast-like cells, valvular interstitial cells (VIC) which are embedded in an extracellular matrix (ECM) scaffold and are submitted to the mechanical deformations affecting valve at each heartbeat, for an average of 40 million times per year. Myxomatous mitral valve (MMV) is the most frequent heart valve disease characterized by disruption of several valvular structures due to alterations of their ECM preventing the complete closure of the valve resulting in symptoms of prolapse and regurgitation. VIC and their ECM exhibit reciprocal dynamic processes between the mechanical signals issued from the ECM and the modulation of VIC phenotype responsible for ECM homeostasis of the valve. Abnormal perception and responsiveness of VIC to mechanical stress may induce an inappropriate adaptative remodeling of the valve progressively leading to MMV. To investigate the response of human VIC to mechanical strain and identify the molecular mechanisms of mechano-transduction in these cells, a cyclic equibiaxial elongation of 14% at the cardiac frequency of 1.16â¯Hz was applied to VIC by using a Flexercell-4000â¯T™ apparatus for increasing time (from 1â¯h to 8â¯h). We showed that cyclic stretch induces an early (1â¯h) and transient over-expression of TGFß2 and αSMA. CTGF, a profibrotic growth factor promoting the synthesis of ECM components, was strongly induced after 1 and 2â¯h of stretching and still upregulated at 8â¯h. The mechanical stress-induced CTGF up-regulation was dependent on RhoC, but not RhoA, as demonstrated by siRNA-mediated silencing approaches, and further supported by evidencing RhoC activation upon cell stretching and suppression of cell response by pharmacological inhibition of the effector ROCK1/2. It was also dependent on the MEK/Erk1/2 pathway which was activated by mechanical stress independently of RhoC and ROCK. Finally, mechanical stretching induced the nuclear translocation of myocardin related transcription factor-A (MRTF-A) which forms a transcriptional complex with SRF to promote the expression of target genes, notably CTGF. Treatment of stretched cultures with inhibitors of the identified pathways (ROCK1/2, MEK/Erk1/2, MRTF-A translocation) blocked CTGF overexpression and abrogated the increased MRTF-A nuclear translocation. CTGF is up-regulated in many pathological processes involving mechanically challenged organs, promotes ECM accumulation and is considered as a hallmark of fibrotic diseases. Pharmacological targeting of MRTF-A by newly developed inhibitors may represent a relevant therapy for MMV.
Asunto(s)
Estenosis de la Válvula Aórtica/genética , Calcinosis/genética , Fibrosis/genética , Válvula Mitral/metabolismo , Válvula Aórtica/metabolismo , Válvula Aórtica/patología , Estenosis de la Válvula Aórtica/patología , Calcinosis/patología , Fibrosis/patología , Humanos , Sistema de Señalización de MAP Quinasas/genética , Válvula Mitral/patología , Estrés Mecánico , Transactivadores/genética , Quinasas Asociadas a rho/genética , Proteína de Unión al GTP rhoA/genéticaRESUMEN
Heart valve cells mediate extracellular matrix (ECM) remodeling during postnatal valve leaflet stratification, but phenotypic and transcriptional diversity of valve cells in development is largely unknown. Single cell analysis of mouse heart valve cells was used to evaluate cell heterogeneity during postnatal ECM remodeling and leaflet morphogenesis. The transcriptomic analysis of single cells from postnatal day (P)7 and P30 murine aortic (AoV) and mitral (MV) heart valves uncovered distinct subsets of melanocytes, immune and endothelial cells present at P7 and P30. By contrast, interstitial cell populations are different from P7 to P30. P7 valve leaflets exhibit two distinct collagen- and glycosaminoglycan-expressing interstitial cell clusters, and prevalent ECM gene expression. At P30, four interstitial cell clusters are apparent with leaflet specificity and differential expression of complement factors, ECM proteins and osteogenic genes. This initial transcriptomic analysis of postnatal heart valves at single cell resolution demonstrates that subpopulations of endothelial and immune cells are relatively constant throughout postnatal development, but interstitial cell subpopulations undergo changes in gene expression and cellular functions in primordial and mature valves.
Asunto(s)
Válvula Aórtica/crecimiento & desarrollo , Matriz Extracelular/química , Válvula Mitral/crecimiento & desarrollo , Animales , Válvula Aórtica/fisiología , Diferenciación Celular , Linaje de la Célula , Análisis por Conglomerados , Colágeno/química , Células Endoteliales/citología , Femenino , Regulación del Desarrollo de la Expresión Génica , Marcadores Genéticos , Glicosaminoglicanos/química , Homeostasis , Humanos , Inmunohistoquímica , Masculino , Melanocitos/citología , Ratones , Válvula Mitral/fisiología , Fenotipo , Análisis de Secuencia de ARN , Análisis de la Célula Individual/métodos , Porcinos , Ingeniería de Tejidos/métodos , TranscriptomaRESUMEN
Calcific Aortic Valve Disease (CAVD) is the most common heart valve disease and its incidence is expected to rise with aging population. No medical treatment so far has shown slowing progression of CAVD progression. Surgery remains to this day the only way to treat it. Effective drug therapy can only be achieved through a better insight into the pathogenic mechanisms underlying CAVD. The cellular and molecular events leading to leaflets calcification are complex. Upon endothelium cell damage, oxidized LDLs trigger a proinflammatory response disrupting healthy cross-talk between valve endothelial and interstitial cells. Therefore, valve interstitial cells transform into osteoblasts and mineralize the leaflets. Studies have investigated signaling pathways driving and connecting lipid metabolism, inflammation and osteogenesis. This review draws a summary of the recent advances and discusses their exploitation as promising therapeutic targets to treat CAVD and reduce valve replacement.
RESUMEN
OBJECTIVE: Hematopoietic-derived cells have been reported in heart valves but remain poorly characterized. Interestingly, recent studies reveal infiltration of leukocytes and increased macrophages in human myxomatous mitral valves. Nevertheless, timing and contribution of macrophages in normal valves and myxomatous valve disease are still unknown. The objective is to characterize leukocytes during postnatal heart valve maturation and identify macrophage subsets in myxomatous valve disease. APPROACH AND RESULTS: Leukocytes are detected in heart valves after birth, and their numbers increase during postnatal valve development. Flow cytometry and immunostaining analysis indicate that almost all valve leukocytes are myeloid cells, consisting of at least 2 differentially localized macrophage subsets and dendritic cells. Beginning a week after birth, increased numbers of CCR2+ (C-C chemokine receptor type 2) macrophages are present, consistent with infiltrating populations of monocytes, and macrophages are localized in regions of biomechanical stress in the valve leaflets. Valve leukocytes maintain expression of CD (cluster of differentiation) 45 and do not contribute to significant numbers of endothelial or interstitial cells. Macrophage lineages were examined in aortic and mitral valves of Axin2 KO (knockout) mice that exhibit myxomatous features. Infiltrating CCR2+ monocytes and expansion of CD206-expressing macrophages are localized in regions where modified heavy chain hyaluronan is observed in myxomatous valve leaflets. Similar colocalization of modified hyaluronan and increased numbers of macrophages were observed in human myxomatous valve disease. CONCLUSIONS: Our study demonstrates the heterogeneity of myeloid cells in heart valves and highlights an alteration of macrophage subpopulations, notably an increased presence of infiltrating CCR2+ monocytes and CD206+ macrophages, in myxomatous valve disease.
Asunto(s)
Linaje de la Célula , Matriz Extracelular/patología , Enfermedades de las Válvulas Cardíacas/patología , Válvulas Cardíacas/patología , Macrófagos/patología , Factores de Edad , Anciano , Animales , Proteína Axina/genética , Proteína Axina/metabolismo , Receptor 1 de Quimiocinas CX3C/genética , Receptor 1 de Quimiocinas CX3C/metabolismo , Células Dendríticas/metabolismo , Células Dendríticas/patología , Modelos Animales de Enfermedad , Matriz Extracelular/metabolismo , Femenino , Regulación del Desarrollo de la Expresión Génica , Genes Reporteros , Enfermedades de las Válvulas Cardíacas/genética , Enfermedades de las Válvulas Cardíacas/metabolismo , Válvulas Cardíacas/metabolismo , Humanos , Ácido Hialurónico/metabolismo , Lectinas Tipo C/metabolismo , Leucocitos/metabolismo , Leucocitos/patología , Proteínas Luminiscentes/genética , Proteínas Luminiscentes/metabolismo , Macrófagos/metabolismo , Masculino , Receptor de Manosa , Lectinas de Unión a Manosa/metabolismo , Ratones de la Cepa 129 , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos , Persona de Mediana Edad , Mutación , Fenotipo , Receptores CCR2/metabolismo , Receptores de Superficie Celular/metabolismoRESUMEN
During postnatal heart valve development, glycosaminoglycan (GAG)-rich valve primordia transform into stratified valve leaflets composed of GAGs, fibrillar collagen, and elastin layers accompanied by decreased cell proliferation as well as thinning and elongation. The neonatal period is characterized by the transition from a uterine environment to atmospheric O2, but the role of changing O2 levels in valve extracellular matrix (ECM) composition or morphogenesis is not well characterized. Here, we show that tissue hypoxia decreases in mouse aortic valves in the days after birth, concomitant with ECM remodeling and cell cycle arrest of valve interstitial cells. The effects of hypoxia on late embryonic valve ECM composition, Sox9 expression, and cell proliferation were examined in chicken embryo aortic valve organ cultures. Maintenance of late embryonic chicken aortic valve organ cultures in a hypoxic environment promotes GAG expression, Sox9 nuclear localization, and indicators of hyaluronan remodeling but does not affect fibrillar collagen content or cell proliferation. Chronic hypoxia also promotes GAG accumulation in murine adult heart valves in vivo. Together, these results support a role for hypoxia in maintaining a primitive GAG-rich matrix in developing heart valves before birth and also in the induction of hyaluronan remodeling in adults.NEW & NOTEWORTHY Tissue hypoxia decreases in mouse aortic valves after birth, and exposure to hypoxia promotes glycosaminoglycan accumulation in cultured chicken embryo valves and adult murine heart valves. Thus, hypoxia maintains a primitive extracellular matrix during heart valve development and promotes extracellular matrix remodeling in adult mice, as occurs in myxomatous disease.
Asunto(s)
Microambiente Celular , Matriz Extracelular/metabolismo , Válvulas Cardíacas/metabolismo , Ácido Hialurónico/metabolismo , Oxígeno/metabolismo , Animales , Animales Recién Nacidos , Hipoxia de la Célula , Proliferación Celular , Embrión de Pollo , Colágenos Fibrilares/metabolismo , Regulación del Desarrollo de la Expresión Génica , Válvulas Cardíacas/embriología , Ratones , Ratones Endogámicos C57BL , Técnicas de Cultivo de Órganos , Organogénesis , Factor de Transcripción SOX9/genética , Factor de Transcripción SOX9/metabolismo , Factores de TiempoRESUMEN
AIMS: Myxomatous valve disease (MVD) is the most common aetiology of primary mitral regurgitation. Recent studies suggest that defects in heart valve development can lead to heart valve disease in adults. Wnt/ß-catenin signalling is active during heart valve development and has been reported in human MVD. The consequences of increased Wnt/ß-catenin signalling due to Axin2 deficiency in postnatal valve remodelling and pathogenesis of MVD were determined. METHODS AND RESULTS: To investigate the role of Wnt/ß-catenin signalling, we analysed heart valves from mice deficient in Axin2 (KO), a negative regulator of Wnt/ß-catenin signalling. Axin2 KO mice display enlarged mitral and aortic valves (AoV) after birth with increased Wnt/ß-catenin signalling and cell proliferation, whereas Sox9 expression and collagen deposition are decreased. At 2 months in Axin2 KO mice, the valve extracellular matrix (ECM) is stratified but distal AoV leaflets remain thickened and develop aortic insufficiency. Progressive myxomatous degeneration is apparent at 4 months with extensive ECM remodelling and focal aggrecan-rich areas, along with increased BMP signalling. Infiltration of inflammatory cells is also observed in Axin2 KO AoV prior to ECM remodelling. Overall, these features are consistent with the progression of human MVD. Finally, Axin2 expression is decreased and Wnt/ß-catenin signalling is increased in myxomatous mitral valves in a murine model of Marfan syndrome, supporting the importance of Wnt/ß-catenin signalling in the development of MVD. CONCLUSIONS: Altogether, these data indicate that Axin2 limits Wnt/ß-catenin signalling after birth and allows proper heart valve maturation. Moreover, dysregulation of Wnt/ß-catenin signalling resulting from loss of Axin2 leads to progressive MVD.
Asunto(s)
Insuficiencia de la Válvula Aórtica/metabolismo , Válvula Aórtica/metabolismo , Proteína Axina/deficiencia , Matriz Extracelular/metabolismo , Cardiopatías Congénitas/metabolismo , Insuficiencia de la Válvula Mitral/metabolismo , Válvula Mitral/metabolismo , Vía de Señalización Wnt , Agrecanos/metabolismo , Animales , Válvula Aórtica/anomalías , Válvula Aórtica/fisiopatología , Insuficiencia de la Válvula Aórtica/patología , Insuficiencia de la Válvula Aórtica/fisiopatología , Proteína Axina/genética , Proteínas Morfogenéticas Óseas/metabolismo , Proliferación Celular , Colágeno/metabolismo , Matriz Extracelular/patología , Fibrilina-1/genética , Fibrilina-1/metabolismo , Regulación del Desarrollo de la Expresión Génica , Predisposición Genética a la Enfermedad , Cardiopatías Congénitas/genética , Cardiopatías Congénitas/patología , Cardiopatías Congénitas/fisiopatología , Síndrome de Marfan/genética , Síndrome de Marfan/metabolismo , Síndrome de Marfan/patología , Ratones Noqueados , Válvula Mitral/anomalías , Válvula Mitral/fisiopatología , Insuficiencia de la Válvula Mitral/genética , Insuficiencia de la Válvula Mitral/patología , Insuficiencia de la Válvula Mitral/fisiopatología , Morfogénesis , Mutación , Fenotipo , Factor de Transcripción SOX9/genética , Factor de Transcripción SOX9/metabolismoRESUMEN
BACKGROUND: Mitral regurgitation is a frequent valvular heart disease affecting around 2.5 % of the population with prevalence directly related to aging. Degeneration of mitral valve is broadly considered as a passive ongoing pathophysiological process and little is known about its physiological deregulation. The purpose of this study was to highlight new biomarkers of mitral regurgitation in order to decipher the underlying pathological mechanism as well as to allow the diagnosis and the monitoring of the disease. RESULTS: Modulation of various blood proteins expression was examined in patients suffering from different grades of mitral regurgitation (mild, moderate and severe) compared to healthy controls. To this end, several routine clinical assays and the multi analyte profile technology targeting 184 proteins were used. High-density lipoprotein, apolipoprotein-A1, haptoglobin and haptoglobin-α2 chain levels significantly decreased proportionally to the degree of mitral regurgitation when compared to controls. High-density lipoprotein and apolipoprotein-A1 levels were associated with effective regurgitant orifice area and regurgitant volume. Apolipoprotein-A1 was an independent predictor of severe mitral regurgitation. Moreover, with ordinal logistic regression, apolipoprotein-A1 remained the only independent factor associated with mitral regurgitation. In addition, myxomatous mitral valves were studied by immunocytochemistry. We observed an increase of LC3, the marker of autophagy, in myxomatous mitral valves compared with healthy mitral valves. CONCLUSION: These potential biomarkers of mitral regurgitation highlighted different cellular processes that could be modified in myxomatous degenerescence: reverse cholesterol transport, antioxidant properties and autophagy.
RESUMEN
OBJECTIVE: The Wnt/ß-catenin signaling pathway has been implicated in human heart valve disease and is required for early heart valve formation in mouse and zebrafish. However, the specific functions of Wnt/ß-catenin signaling activity in heart valve maturation and maintenance in adults have not been determined previously. APPROACH AND RESULTS: Here, we show that Wnt/ß-catenin signaling inhibits Sox9 nuclear localization and proteoglycan expression in cultured chicken embryo aortic valves. Loss of ß-catenin in vivo in mice, using Periostin(Postn)Cre-mediated tissue-restricted loss of ß-catenin (Ctnnb1) in valvular interstitial cells, leads to the formation of aberrant chondrogenic nodules and induction of chondrogenic gene expression in adult aortic valves. These nodular cells strongly express nuclear Sox9 and Sox9 downstream chondrogenic extracellular matrix genes, including Aggrecan, Col2a1, and Col10a1. Excessive chondrogenic proteoglycan accumulation and disruption of stratified extracellular matrix maintenance in the aortic valve leaflets are characteristics of myxomatous valve disease. Both in vitro and in vivo data demonstrate that the loss of Wnt/ß-catenin signaling leads to increased nuclear expression of Sox9 concomitant with induced expression of chondrogenic extracellular matrix proteins. CONCLUSIONS: ß-Catenin limits Sox9 nuclear localization and inhibits chondrogenic differentiation during valve development and in adult aortic valve homeostasis.
Asunto(s)
Válvula Aórtica/citología , Válvula Aórtica/metabolismo , beta Catenina/metabolismo , Animales , Válvula Aórtica/embriología , Válvula Aórtica/patología , Proteínas Aviares/metabolismo , Enfermedad de la Válvula Aórtica Bicúspide , Diferenciación Celular/genética , Diferenciación Celular/fisiología , Embrión de Pollo , Condrogénesis/genética , Condrogénesis/fisiología , Proteínas de la Matriz Extracelular/genética , Proteínas de la Matriz Extracelular/metabolismo , Expresión Génica , Cardiopatías Congénitas/genética , Cardiopatías Congénitas/metabolismo , Cardiopatías Congénitas/patología , Enfermedades de las Válvulas Cardíacas/genética , Enfermedades de las Válvulas Cardíacas/metabolismo , Enfermedades de las Válvulas Cardíacas/patología , Humanos , Ratones , Ratones Noqueados , Proteoglicanos/metabolismo , Factor de Transcripción SOX9/metabolismo , Vía de Señalización Wnt , beta Catenina/deficiencia , beta Catenina/genéticaRESUMEN
Mature heart valves are complex structures consisting of three highly organized extracellular matrix layers primarily composed of collagens, proteoglycans and elastin. Collectively, these diverse matrix components provide all the necessary biomechanical properties for valve function throughout life. In contrast to healthy valves, myxomatous valve disease is the most common cause of mitral valve prolapse in the human population and is characterized by an abnormal abundance of proteoglycans within the valve tri-laminar structure. Despite the clinical significance, the etiology of this phenotype is not known. Scleraxis (Scx) is a basic-helix-loop-helix transcription factor that we previously showed to be required for establishing heart valve structure during remodeling stages of valvulogenesis. In this study, we report that remodeling heart valves from Scx null mice express decreased levels of proteoglycans, particularly chondroitin sulfate proteoglycans (CSPGs), while overexpression in embryonic avian valve precursor cells and adult porcine valve interstitial cells increases CSPGs. Using these systems we further identify that Scx is positively regulated by canonical Tgfß2 signaling during this process and this is attenuated by MAPK activity. Finally, we show that Scx is increased in myxomatous valves from human patients and mouse models, and overexpression in human mitral valve interstitial cells modestly increases proteoglycan expression consistent with myxomatous mitral valve phenotypes. Together, these studies identify an important role for Scx in regulating proteoglycans in embryonic and mature valve cells and suggest that imbalanced regulation could influence myxomatous pathogenesis.
Asunto(s)
Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Válvulas Cardíacas/metabolismo , Sistema de Señalización de MAP Quinasas , Proteoglicanos/metabolismo , Proteínas Smad/metabolismo , Factor de Crecimiento Transformador beta/metabolismo , Animales , Animales Recién Nacidos , Pollos , Modelos Animales de Enfermedad , Válvulas Cardíacas/embriología , Válvulas Cardíacas/patología , Humanos , Ratones , Válvula Mitral/embriología , Válvula Mitral/metabolismo , Válvula Mitral/patología , Células 3T3 NIH , Sus scrofaRESUMEN
INTRODUCTION: Myxomatous mitral valve is one of the most common heart valves diseases in human and has been well characterized at a functional and morphological level. Diseased valves are thickened as a result of extracellular matrix remodeling and proteoglycans accumulation accompanied by the disruption of the stratified structures of the leaflets. METHODS: Global transcriptomic analysis was used as a start-up to investigate potential pathogenic mechanisms involved in the development of the human idiopathic myxomatous mitral valve, which have been elusive for many years. RESULTS: These prospective analyses have highlighted the potential role of apparently unrelated molecules in myxomatous mitral valve such as members of the transforming growth factor-ß superfamily, aggrecanases of the "a disintegrin and metalloprotease with thrombospondin repeats I" family, and a weakening of the protection against oxidative stress. We have integrated, in this review, recent transcriptomic data from our laboratory [A. Hulin, C.F. Deroanne, C.A. Lambert, B. Dumont, V. Castronovo, J.O. Defraigne, et al. Metallothionein-dependent up-regulation of TGF-beta2 participates in the remodelling of the myxomatous mitral valve. Cardiovasc Res 2012;93:480-489] and from the publication of Sainger et al. [R. Sainger, J.B. Grau, E. Branchetti, P. Poggio, W.F. Seefried, B.C. Field, et al. Human myxomatous mitral valve prolapse: role of bone morphogenetic protein 4 in valvular interstitial cell activation. J Cell Physiol 2012;227:2595-2604] with existing literature and information issued from the study of monogenic syndromes and animal models. CONCLUSION: Understanding cellular alterations and molecular mechanisms involved in myxomatous mitral valve should help at identifying relevant targets for future effective pharmacological therapy to prevent or reduce its progression.
Asunto(s)
Prolapso de la Válvula Mitral/patología , Válvula Mitral/patología , Proteínas ADAM/genética , Proteínas ADAM/metabolismo , Animales , Modelos Animales de Enfermedad , Matriz Extracelular/genética , Matriz Extracelular/metabolismo , Perfilación de la Expresión Génica/métodos , Predisposición Genética a la Enfermedad , Humanos , Válvula Mitral/metabolismo , Prolapso de la Válvula Mitral/genética , Prolapso de la Válvula Mitral/metabolismo , Estrés Oxidativo , Fenotipo , Pronóstico , Proteoglicanos/genética , Proteoglicanos/metabolismo , Serotonina/metabolismo , Transducción de Señal , Proteínas de la Superfamilia TGF-beta/genética , Proteínas de la Superfamilia TGF-beta/metabolismo , TranscriptomaRESUMEN
AIMS: Although an excessive extracellular matrix remodelling has been well described in myxomatous mitral valve (MMV), the underlying pathogenic mechanisms remain largely unknown. Our goal was to identify dysregulated genes in human MMV and then to evaluate their functional role in the progression of the disease. METHODS AND RESULTS: Dysregulated genes were investigated by transcriptomic, immunohistochemistry, and western blot analyses of the P2 segment collected from human idiopathic MMV during valvuloplasty (n = 23) and from healthy control valves (n = 17). The most striking results showed a decreased expression of two families of genes: the metallothioneins-1 and -2 (MT1/2) and members of the ADAMTS. The mechanistic consequences of the reduced level of MT1/2 were evaluated by silencing their expression in normal valvular interstitial cells (VICs) cultures. The knock-down of MT1/2 resulted in the up-regulation of transforming growth factor-beta 2 (TGF-ß2). Most importantly, TGF-ß2 was also found significantly increased in MMV tissues. The activation of VICs in vitro by TGF-ß2 induced a down-regulation of ADAMTS-1 and an accumulation of versican as observed in human MMV. CONCLUSION: Our studies demonstrate for the first time that MMV are characterized by reduced levels of MT1/2 accompanied by an up-regulation of TGF-ß2. In turn, increased TGF-ß2 signalling induces down-regulation of aggrecanases and up-regulation of versican, two co-operating processes that potentially participate in the development of the pathology.