Abnormal Flow Conditions Promote Endocardial Fibroelastosis Via Endothelial-to-Mesenchymal Transition, Which Is Responsive to Losartan Treatment.
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ABSTRACT:
SUBMITTER: Oh NA
PROVIDER: S-EPMC8733675 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Endocardial fibroelastosis (EFE) is a unique form of fibrosis, which forms a de novo subendocardial tissue layer encapsulating the myocardium and stunting its growth, and which is typically associated with congenital heart diseases of heterogeneous origin, such as hypoplastic left heart syndrome. Relevance of EFE was only recently highlighted through the establishment of staged biventricular repair surgery in infant patients with hypoplastic left heart syndrome, where surgical removal of EFE tissue has resulted in improvement in the restrictive physiology leading to the growth of the left ventricle in parallel with somatic growth. However, pathomechanisms underlying EFE formation are still scarce, and specific therapeutic targets are not yet known.Here, we aimed to investigate the cellular origins of EFE tissue and to gain insights into the underlying molecular mechanisms to ultimately develop novel therapeutic strategies.By utilizing a novel EFE model of heterotopic transplantation of hearts from newborn reporter mice and by analyzing human EFE tissue, we demonstrate for the first time that fibrogenic cells within EFE tissue originate from endocardial endothelial cells via aberrant endothelial to mesenchymal transition. We further demonstrate that such aberrant endothelial to mesenchymal transition involving endocardial endothelial cells is caused by dysregulated transforming growth factor beta/bone morphogenetic proteins signaling and that this imbalance is at least in part caused by aberrant promoter methylation and subsequent transcriptional suppression of bone morphogenetic proteins 5 and 7. Finally, we provide evidence that supplementation of exogenous recombinant bone morphogenetic proteins 7 effectively ameliorates endothelial to mesenchymal transition and experimental EFE in rats.In summary, our data point to aberrant endothelial to mesenchymal transition as a common denominator of infant EFE development in heterogeneous, congenital heart diseases, and to bone morphogenetic proteins 7 as an effective treatment for EFE and its restriction of heart growth.
| S-EPMC4344885 | biostudies-literature
Project description:BACKGROUND:Endocardial fibroelastosis (EFE) is a pathologic condition of abnormal deposition of collagen and elastin within the endocardium of the heart. It is seen in conjunction with a variety of diseases including hypoplastic left heart syndrome and viral endocarditis. While an experimental model using heterotopic heart transplant in rats has been described, we sought to fully describe a mouse model that can be used to further elucidate the potential mechanisms of and treatments for EFE. MATERIALS AND METHODS:The hearts of 2-day-old C57BL/6 mice were transplanted into the abdomen of 7-week-old C57BL/6 mice. At 2 weeks, the hearts were harvested and histologic analysis was performed using hematoxylin and eosin, Masson's trichrome, Russell-Movat's pentachrome, Picrosirius red, Hart's, Verhoeff-Van Gieson, and Weigert's Resorcin-Fuchsin stains. Additionally, one heart was analyzed using transmission electron microscopy (TEM). RESULTS:Specimens demonstrated abnormal accumulation of both collagen and elastin within the endocardium with occasional expansion into the myocardium. Heterogeneity in extracellular matrix deposition was noted in the histologic specimens. In addition, TEM demonstrated the presence of excess collagen within the endocardium. CONCLUSIONS:The heterotopic transplantation of an immature heart into a mouse results in changes consistent with EFE. This model is appropriate to investigate the etiology and treatment of EFE.
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Project description:Four variants (K60N, Q128R, G202R, and A592E) in the nebulette gene were identified in patients with dilated cardiomyopathy (DCM) and endocardial fibroelastosis. We sought to determine if these mutations are cardiomyopathy causing.Nebulette aligns thin filaments and connects them with the myocardial Z-disk, playing a role in mechanosensation.We generated transgenic mice with cardiac-restricted overexpression of human wild-type or mutant nebulette. Chimera and transgenic mice were examined at 4, 6, and 12 months of age by echocardiography and cardiac magnetic resonance imaging. The hearts from embryos and adult mice were assessed by histopathologic, immunohistochemical, ultrastructural, and protein analyses. Rat H9C2 cardiomyoblasts with transient expression of nebulette underwent cyclic mechanical strain.We identified lethal cardiac structural abnormalities in mutant embryonic hearts (K60N and Q128R). Founders of the mutant mouse lines developed DCM with severe heart failure. An irregular localization pattern for nebulette and impaired desmin expression were noted in the proband and chimeric Q128R mice. Mutant G202R and A592E mice exhibited left ventricular dilation and impaired function with specific changes in I-band and Z-disk proteins by 6 months of age. The mutations modulated distribution of nebulette in the sarcomere and Z-disk during stretch of H9C2 cells.Nebulette is a new susceptibility gene for endocardial fibroelastosis and DCM. Different mutations in nebulette trigger specific mechanisms, converging to a common pathological cascade leading to endocardial fibroelastosis and DCM.
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Project description:•The authors report a patient with biopsy-proven adult endocardial fibroelastosis.•Transthoracic echocardiography revealed diffuse coarse endocardial calcifications.•Native CT of the chest revealed LV endocardial calcifications.
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Project description:Endocardial fibroelastosis (EFE) refers to the thickening of the ventricular endocardium as a result of de novo deposition of subendocardial fibrous tissue layers during neonatal heart development. The origin of EFE fibroblasts is proposed to be postnatal endocardial cells that undergo an aberrant endothelial-to-mesenchymal transition (EndMT). Genetic lineage tracing of endocardial cells with the inducible endocardial Cre line Npr3-CreER and the endothelial cell tracing line Cdh5-CreER on an EFE-like model did not reveal any contribution of neonatal endocardial cells to fibroblasts in the EFE-like tissues. Instead, lineage tracing of embryonic epicardium by Wt1-CreER suggested that epicardium-derived mesenchymal cells (MCs) served as the major source of EFE fibroblasts. By labeling MCs using Sox9-CreER, we confirmed that MCs of the embryonic heart expand and contribute to the majority of neonatal EFE fibroblasts. During this pathological process, TGF? signaling, the key mediator of fibroblasts activation, was highly upregulated in the EFE-like tissues. Targeting TGF? signaling by administration of its antagonist bone morphogenetic protein 7 effectively reduced fibroblast accumulation and tissue fibrosis in the EFE-like model. Our study provides genetic evidence that excessive fibroblasts in the EFE-like tissues mainly originate from the epicardium-derived MCs through epicardial to mesenchymal transition (EpiMT). These EpiMT-derived fibroblasts within the EFE-like tissues could serve as a potential therapeutic target.
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Project description:The Nexilin F-Actin Binding Protein (Nexilin) encoded by NEXN is a cardiac Z-disc protein important for cardiac function and development in humans, zebrafish, and mice. Heterozygote variants in the human NEXN gene have been reported to cause dilated and hypertrophic cardiomyopathy. Homozygous variants in NEXN cause a lethal form of human fetal cardiomyopathy, only described in two patients before. In a Swedish, four-generation, non-consanguineous family comprising 42 individuals, one female had three consecutive pregnancies with intrauterine fetal deaths caused by a lethal form of dilated cardiomyopathy. Whole-exome sequencing and variant analysis revealed that the affected fetuses were homozygous for a NEXN variant (NM_144573:c.1302del;p.(Ile435Serfs*3)). Moreover, autopsy and histology staining declared that they presented with cardiomegaly and endocardial fibroelastosis. Immunohistochemistry staining for Nexilin in the affected fetuses revealed reduced antibody staining and loss of striation in the heart, supporting loss of Nexilin function. Clinical examination of seven heterozygote carriers confirmed dilated cardiomyopathy (two individuals), other cardiac findings (three individuals), or no cardiac deviations (two individuals), indicating incomplete penetrance or age-dependent expression of dilated cardiomyopathy. RNA sequencing spanning the variant in cDNA blood of heterozygote individuals revealed nonsense-mediated mRNA decay of the mutated transcripts. In the current study, we present the first natural course of the recessively inherited lethal form of human fetal cardiomyopathy caused by loss of Nexilin function. The affected family had uneventful pregnancies until week 23-24, followed by fetal death at week 24-30, characterized by cardiomegaly and endocardial fibroelastosis.
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Project description:Extracellular vesicles released by tumors (tEVs) disseminate via circulatory networks and promote microenvironmental changes in distant organs favoring metastatic seeding. Despite their abundance in the bloodstream, how hemodynamics affect the function of circulating tEVs remains unsolved. We experimentally tuned flow profiles in vitro (microfluidics) and in vivo (zebrafish) and demonstrated that efficient uptake of tEVs occurs in endothelial cells subjected to capillary-like hemodynamics. Such flow profiles partially reroute internalized tEVs towards non-acidic and non-degradative Rab14-positive endosomes, at the expense of lysosomes, suggesting that endothelial mechanosensing diverts tEVs from degradation. Subsequently, tEVs promote the expression of pro-angiogenic transcription factors in flow-stimulated endothelial cells and favor vessel sprouting in zebrafish. Altogether, we demonstrate that capillary-like flow profiles potentiate the pro-tumoral function of circulating tEVs by promoting their uptake and rerouting their trafficking. We propose that tEVs contribute to pre-metastatic niche formation by exploiting endothelial mechanosensing in specific vascular regions with permissive hemodynamics. This set of experiments represents RNAseq of HUVEC cells subjected to 400 µm/s flow versus no flow (static conditon).
2023-07-11 | E-MTAB-13156 | biostudies-arrayexpress
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