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BACKGROUND: TGF (transforming growth factor)-ß pathway is central to blood-brain barrier development as it regulates cross talk between pericytes and endothelial cells. Murine embryos lacking TGFß receptor Alk5 (activin receptor-like kinase 5) in brain pericytes (mutants) display endothelial cell hyperproliferation, abnormal vessel morphology, and gross germinal matrix hemorrhage-intraventricular hemorrhage (GMH-IVH), leading to perinatal lethality. Mechanisms underlying how ALK5 signaling in pericytes noncell autonomously regulates endothelial cell behavior remain elusive. METHODS: Transcriptomic analysis of human brain pericytes with ALK5 silencing identified differential gene expression. Brain vascular cells isolated from mutant embryonic mice with GMH-IVH and preterm human IVH brain samples were utilized for target validation. Finally, pharmacological and genetic inhibition was used to study the therapeutic effects on GMH-IVH pathology. RESULTS: Herein, we establish that the TGFß/ALK5 pathway robustly represses ANGPT2 (angiopoietin-2) in pericytes via epigenetic remodeling. TGFß-driven SMAD (suppressor of mothers against decapentaplegic) 3/4 associates with TGIF1 (TGFß-induced factor homeobox 1) and HDAC (histone deacetylase) 5 to form a corepressor complex at the Angpt2 promoter, resulting in promoter deacetylation and gene repression. Moreover, murine and human germinal matrix vessels display increased ANGPT2 expression during GMH-IVH. Isolation of vascular cells from murine germinal matrix identifies pericytes as a cellular source of excessive ANGPT2. In addition, mutant endothelial cells exhibit higher phosphorylated TIE2 (tyrosine protein kinase receptor). Pharmacological or genetic inhibition of ANGPT2 in mutants improves germinal matrix vessel morphology and attenuates GMH pathogenesis. Importantly, genetic ablation of Angpt2 in mutant pericytes prevents perinatal lethality, prolonging survival. CONCLUSIONS: This study demonstrates that TGFß-mediated ANGPT2 repression in pericytes is critical for maintaining blood-brain barrier integrity and identifies pericyte-derived ANGPT2 as an important pathological target for GMH-IVH.
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Angiopoyetina 2 , Pericitos , Factor de Crecimiento Transformador beta , Pericitos/metabolismo , Pericitos/patología , Animales , Ratones , Humanos , Angiopoyetina 2/metabolismo , Angiopoyetina 2/genética , Factor de Crecimiento Transformador beta/metabolismo , Receptor Tipo I de Factor de Crecimiento Transformador beta/metabolismo , Receptor Tipo I de Factor de Crecimiento Transformador beta/genética , Hemorragia Cerebral/metabolismo , Hemorragia Cerebral/patología , Hemorragia Cerebral/genética , Transducción de Señal/fisiología , Receptores de Factores de Crecimiento Transformadores beta/metabolismo , Receptores de Factores de Crecimiento Transformadores beta/genética , Células Endoteliales/metabolismo , Proteínas Serina-Treonina Quinasas/genética , Proteínas Serina-Treonina Quinasas/metabolismoRESUMEN
BACKGROUND: Vascular smooth muscle cell (VSMC) phenotypic switching contributes to cardiovascular diseases. Epigenetic regulation is emerging as a key regulatory mechanism, with the methylcytosine dioxygenase TET2 acting as a master regulator of smooth muscle cell phenotype. The histone acetyl-transferases p300 and CREB-binding protein (CBP) are highly homologous and often considered to be interchangeable, and their roles in smooth muscle cell phenotypic regulation are not known. METHODS: We assessed the roles of p300 and CBP in human VSMC with knockdown, in inducible smooth muscle-specific knockout mice (inducible knockout [iKO]; p300iKO or CBPiKO), and in samples of human intimal hyperplasia. RESULTS: P300, CBP, and histone acetylation were differently regulated in VSMCs undergoing phenotypic switching and in vessel remodeling after vascular injury. Medial p300 expression and activity were repressed by injury, but CBP and histone acetylation were induced in neointima. Knockdown experiments revealed opposing effects of p300 and CBP in the VSMC phenotype: p300 promoted contractile protein expression and inhibited migration, but CBP inhibited contractile genes and enhanced migration. p300iKO mice exhibited severe intimal hyperplasia after arterial injury compared with controls, whereas CBPiKO mice were entirely protected. In normal aorta, p300iKO reduced, but CBPiKO enhanced, contractile protein expression and contractility compared with controls. Mechanistically, we found that these histone acetyl-transferases oppositely regulate histone acetylation, DNA hydroxymethylation, and PolII (RNA polymerase II) binding to promoters of differentiation-specific contractile genes. Our data indicate that p300 and TET2 function together, because p300 was required for TET2-dependent hydroxymethylation of contractile promoters, and TET2 was required for p300-dependent acetylation of these loci. TET2 coimmunoprecipitated with p300, and this interaction was enhanced by rapamycin but repressed by platelet-derived growth factor (PDGF) treatment, with p300 promoting TET2 protein stability. CBP did not associate with TET2, but instead facilitated recruitment of histone deacetylases (HDAC2, HDAC5) to contractile protein promoters. Furthermore, CBP inhibited TET2 mRNA levels. Immunostaining of cardiac allograft vasculopathy samples revealed that p300 expression is repressed but CBP is induced in human intimal hyperplasia. CONCLUSIONS: This work reveals that p300 and CBP serve nonredundant and opposing functions in VSMC phenotypic switching and coordinately regulate chromatin modifications through distinct functional interactions with TET2 or HDACs. Targeting specific histone acetyl-transferases may hold therapeutic promise for cardiovascular diseases.
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Enfermedades Cardiovasculares , Músculo Liso Vascular , Factores de Transcripción p300-CBP/metabolismo , Acetilación , Animales , Proteína de Unión a CREB/genética , Proteína de Unión a CREB/metabolismo , Enfermedades Cardiovasculares/metabolismo , Ensamble y Desensamble de Cromatina , Proteínas Contráctiles/metabolismo , Epigénesis Genética , Histonas/metabolismo , Humanos , Hiperplasia/metabolismo , Ratones , Ratones Noqueados , Músculo Liso Vascular/metabolismo , Miocitos del Músculo Liso/metabolismoRESUMEN
Smooth muscle cells (SMCs) are a critical component of blood vessel walls that provide structural support, regulate vascular tone, and allow for vascular remodeling. These cells also exhibit a remarkable plasticity that contributes to vascular growth and repair but also to cardiovascular pathologies, including atherosclerosis, intimal hyperplasia and restenosis, aneurysm, and transplant vasculopathy. Mouse models have been an important tool for the study of SMC functions. The development of smooth muscle-expressing Cre-driver lines has allowed for exciting discoveries, including recent advances revealing the diversity of phenotypes derived from mature SMC transdifferentiation in vivo using inducible CreER T2 lines. We review SMC-targeting Cre lines driven by the Myh11, Tagln, and Acta2 promoters, including important technical considerations associated with these models. Limitations that can complicate study of the vasculature include expression in visceral SMCs leading to confounding phenotypes, and expression in multiple nonsmooth muscle cell types, such as Acta2-Cre expression in myofibroblasts. Notably, the frequently employed Tagln/ SM22α- Cre driver expresses in the embryonic heart but can also confer expression in nonmuscular cells including perivascular adipocytes and their precursors, myeloid cells, and platelets, with important implications for interpretation of cardiovascular phenotypes. With new Cre-driver lines under development and the increasing use of fate mapping methods, we are entering an exciting new era in SMC research.
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Marcación de Gen/métodos , Músculo Liso Vascular/fisiología , Regiones Promotoras Genéticas , Actinas/biosíntesis , Actinas/genética , Animales , Línea Celular , Linaje de la Célula , Transdiferenciación Celular , Regulación de la Expresión Génica , Técnicas de Inactivación de Genes , Humanos , Ratones , Proteínas de Microfilamentos/biosíntesis , Proteínas de Microfilamentos/genética , Proteínas Musculares/biosíntesis , Proteínas Musculares/genética , Miocitos del Músculo Liso/fisiología , Miofibroblastos/fisiología , Cadenas Pesadas de Miosina/biosíntesis , Cadenas Pesadas de Miosina/genética , Neovascularización Patológica/fisiopatología , Neovascularización Fisiológica , Fenotipo , Proteínas Recombinantes de Fusión/metabolismoRESUMEN
OBJECTIVE: Elastin deficiency because of heterozygous loss of an ELN allele in Williams syndrome causes obstructive aortopathy characterized by medial thickening and fibrosis and consequent aortic stiffening. Previous work in Eln-null mice with a severe arterial phenotype showed that inhibition of mTOR (mechanistic target of rapamycin), a key regulator of cell growth, lessened the aortic obstruction but did not prevent early postnatal death. We investigated the effects of mTOR inhibition in Eln-null mice partially rescued by human ELN that manifest a less severe arterial phenotype and survive long term. APPROACH AND RESULTS: Thoracic aortas of neonatal and juvenile mice with graded elastin deficiency exhibited increased signaling through both mTOR complex 1 and 2. Despite lower predicted wall stress, there was increased phosphorylation of focal adhesion kinase, suggestive of greater integrin activation, and increased transforming growth factor-ß-signaling mediators, associated with increased collagen expression. Pharmacological blockade of mTOR by rapalogs did not improve luminal stenosis but reduced mechanosignaling (in delayed fashion after mTOR complex 1 inhibition), medial collagen accumulation, and stiffening of the aorta. Rapalog administration also retarded somatic growth, however, and precipitated neonatal deaths. Complementary, less-toxic strategies to inhibit mTOR via altered growth factor and nutrient responses were not effective. CONCLUSIONS: In addition to previously demonstrated therapeutic benefits of rapalogs decreasing smooth muscle cell proliferation in the absence of elastin, we find that rapalogs also prevent aortic fibrosis and stiffening attributable to partial elastin deficiency. Our findings suggest that mTOR-sensitive perturbation of smooth muscle cell mechanosensing contributes to elastin aortopathy.
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Enfermedades de la Aorta/tratamiento farmacológico , Colágeno/metabolismo , Elastina/deficiencia , Mecanotransducción Celular/efectos de los fármacos , Músculo Liso Vascular/efectos de los fármacos , Inhibidores de Proteínas Quinasas/farmacología , Serina-Treonina Quinasas TOR/antagonistas & inhibidores , Rigidez Vascular/efectos de los fármacos , Síndrome de Williams/tratamiento farmacológico , Animales , Aorta Torácica/efectos de los fármacos , Aorta Torácica/enzimología , Aorta Torácica/patología , Aorta Torácica/fisiopatología , Enfermedades de la Aorta/enzimología , Enfermedades de la Aorta/patología , Enfermedades de la Aorta/fisiopatología , Proliferación Celular/efectos de los fármacos , Elastina/genética , Everolimus/farmacología , Quinasa 1 de Adhesión Focal/metabolismo , Predisposición Genética a la Enfermedad , Humanos , Mesilato de Imatinib/farmacología , Diana Mecanicista del Complejo 1 de la Rapamicina , Diana Mecanicista del Complejo 2 de la Rapamicina , Ratones Endogámicos C57BL , Ratones Noqueados , Complejos Multiproteicos/metabolismo , Músculo Liso Vascular/enzimología , Músculo Liso Vascular/patología , Músculo Liso Vascular/fisiopatología , Fenotipo , Fosforilación , Sirolimus/farmacología , Serina-Treonina Quinasas TOR/metabolismo , Factores de Tiempo , Síndrome de Williams/enzimología , Síndrome de Williams/patología , Síndrome de Williams/fisiopatologíaAsunto(s)
Capilares/citología , Circulación Cerebrovascular/fisiología , Enfermedad , Salud , Pericitos/fisiología , Animales , Femenino , MasculinoRESUMEN
Arteries consist of an inner single layer of endothelial cells surrounded by layers of smooth muscle and an outer adventitia. The majority of vascular developmental studies focus on the construction of endothelial networks through the process of angiogenesis. Although many devastating vascular diseases involve abnormalities in components of the smooth muscle and adventitia (i.e., the vascular wall), the morphogenesis of these layers has received relatively less attention. Here, we briefly review key elements underlying endothelial layer formation and then focus on vascular wall development, specifically on smooth muscle cell origins and differentiation, patterning of the vascular wall, and the role of extracellular matrix and adventitial progenitor cells. Finally, we discuss select human diseases characterized by marked vascular wall abnormalities. We propose that continuing to apply approaches from developmental biology to the study of vascular disease will stimulate important advancements in elucidating disease mechanism and devising novel therapeutic strategies.
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Arterias/patología , Enfermedades Cardiovasculares/patología , Endotelio Vascular/patología , Morfogénesis/genética , Músculo Liso Vascular/patología , Proteínas Angiogénicas/genética , Proteínas Angiogénicas/metabolismo , Animales , Arterias/crecimiento & desarrollo , Arterias/metabolismo , Enfermedades Cardiovasculares/genética , Enfermedades Cardiovasculares/metabolismo , Diferenciación Celular , Linaje de la Célula/genética , Células Endoteliales/metabolismo , Células Endoteliales/patología , Endotelio Vascular/crecimiento & desarrollo , Endotelio Vascular/metabolismo , Regulación del Desarrollo de la Expresión Génica , Humanos , Músculo Liso Vascular/crecimiento & desarrollo , Músculo Liso Vascular/metabolismo , Miocitos del Músculo Liso/metabolismo , Miocitos del Músculo Liso/patología , Neovascularización Patológica , Neovascularización FisiológicaRESUMEN
Smooth muscle cell (SMC) accumulation is central to the pathogenesis of elastin-defective arterial diseases, including supravalvular aortic stenosis (SVAS). We previously demonstrated that elastin insufficiency activates Notch signaling in aortic SMCs. Activation of Notch is catalyzed by the enzyme gamma-secretase, but the role of catalytic subunits presenilin (PSEN)-1 or PSEN-2 in elastin aortopathy is not defined. Genetic approaches reveal that endothelial cell-specific Psen1 deletion does not improve elastin aortopathy whereas the deletion of either Psen1 in SMCs or Psen2 globally attenuates Notch pathway and SMC proliferation, mitigating aortic disease. With SMC-specific Psen1 deletion in elastin nulls, these rescue effects are more robust and in fact, survival is increased. SMC deletion of Psen1 also attenuates hypermuscularization in newborns heterozygous for the elastin null gene, which genetically mimics SVAS. Similarly, the pharmacological inhibition of PSEN-1 mitigates SMC accumulation in elastin aortopathy. These findings put forth SMC PSEN-1 as a potential therapeutic target in SVAS.
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Mechanisms underlying maintenance of pathological vascular hypermuscularization are poorly delineated. Herein, we investigated retention of smooth muscle cells (SMCs) coating normally unmuscularized distal pulmonary arterioles in pulmonary hypertension (PH) mediated by chronic hypoxia with or without Sugen 5416, and reversal of this pathology. With hypoxia in mice or culture, lung endothelial cells (ECs) upregulated hypoxia-inducible factor 1α (HIF1-α) and HIF2-α, which induce platelet-derived growth factor B (PDGF-B), and these factors were reduced to normoxic levels with re-normoxia. Re-normoxia reversed hypoxia-induced pulmonary vascular remodeling, but with EC HIFα overexpression during re-normoxia, pathological changes persisted. Conversely, after establishment of distal muscularization and PH, EC-specific deletion of Hif1a, Hif2a, or Pdgfb induced reversal. In human idiopathic pulmonary artery hypertension, HIF1-α, HIF2-α, PDGF-B, and autophagy-mediating gene products, including Beclin1, were upregulated in pulmonary artery SMCs and/or lung lysates. Furthermore, in mice, hypoxia-induced EC-derived PDGF-B upregulated Beclin1 in distal arteriole SMCs, and after distal muscularization was established, re-normoxia, EC Pdgfb deletion, or treatment with STI571 (which inhibits PDGF receptors) downregulated SMC Beclin1 and other autophagy products. Finally, SMC-specific Becn1 deletion induced apoptosis, reversing distal muscularization and PH mediated by hypoxia with or without Sugen 5416. Thus, chronic hypoxia induction of the HIFα/PDGF-B axis in ECs is required for non-cell-autonomous Beclin1-mediated survival of pathological distal arteriole SMCs.
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Beclina-1 , Células Endoteliales , Hipertensión Pulmonar , Subunidad alfa del Factor 1 Inducible por Hipoxia , Miocitos del Músculo Liso , Proteínas Proto-Oncogénicas c-sis , Transducción de Señal , Animales , Beclina-1/metabolismo , Beclina-1/genética , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Subunidad alfa del Factor 1 Inducible por Hipoxia/genética , Ratones , Humanos , Hipertensión Pulmonar/metabolismo , Hipertensión Pulmonar/patología , Hipertensión Pulmonar/genética , Proteínas Proto-Oncogénicas c-sis/metabolismo , Proteínas Proto-Oncogénicas c-sis/genética , Miocitos del Músculo Liso/metabolismo , Miocitos del Músculo Liso/patología , Células Endoteliales/metabolismo , Masculino , Remodelación Vascular , Músculo Liso Vascular/metabolismo , Músculo Liso Vascular/patología , Hipoxia/metabolismo , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Arteria Pulmonar/metabolismo , Arteria Pulmonar/patología , Autofagia , Modelos Animales de Enfermedad , Arteriolas/metabolismo , Arteriolas/patología , Indoles , PirrolesRESUMEN
Midlobular hepatocytes are proposed to be the most plastic hepatic cell, providing a reservoir for hepatocyte proliferation during homeostasis and regeneration. However, other mechanisms beyond hyperplasia have been little explored and the contribution of other hepatocyte subpopulations to regeneration has been controversial. Thus, re-examining hepatocyte dynamics during regeneration is critical for cell therapy and treatment of liver diseases. Using a mouse model of hepatocyte- and non-hepatocyte- multicolor lineage tracing, we demonstrate that midlobular hepatocytes also undergo hypertrophy in response to chemical, physical, and viral insults. Our study shows that this subpopulation also combats liver impairment after infection with coronavirus. Furthermore, we demonstrate that pericentral hepatocytes also expand in number and size during the repair process and Galectin-9-CD44 pathway may be critical for driving these processes. Notably, we also identified that transdifferentiation and cell fusion during regeneration after severe injury contribute to recover hepatic function.
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Hepatopatías , Regeneración Hepática , Animales , Regeneración Hepática/fisiología , Hígado/metabolismo , Hepatocitos/metabolismo , Hepatopatías/metabolismo , Modelos Animales de Enfermedad , Proliferación CelularRESUMEN
Alveolarization ensures sufficient lung surface area for gas exchange, and during bulk alveolarization in mice (postnatal day [P] 4.5-14.5), alpha-smooth muscle actin (SMA)+ myofibroblasts accumulate, secrete elastin, and lay down alveolar septum. Herein, we delineate the dynamics of the lineage of early postnatal SMA+ myofibroblasts during and after bulk alveolarization and in response to lung injury. SMA+ lung myofibroblasts first appear at â¼ P2.5 and proliferate robustly. Lineage tracing shows that, at P14.5 and over the next few days, the vast majority of SMA+ myofibroblasts downregulate smooth muscle cell markers and undergo apoptosis. Of note, â¼8% of these dedifferentiated cells and another â¼1% of SMA+ myofibroblasts persist to adulthood. Single cell RNA sequencing analysis of the persistent SMA- cells and SMA+ myofibroblasts in the adult lung reveals distinct gene expression profiles. For instance, dedifferentiated SMA- cells exhibit higher levels of tissue remodeling genes. Most interestingly, these dedifferentiated early postnatal myofibroblasts re-express SMA upon exposure of the adult lung to hypoxia or the pro-fibrotic drug bleomycin. However, unlike during alveolarization, these cells that re-express SMA do not proliferate with hypoxia. In sum, dedifferentiated early postnatal myofibroblasts are a previously undescribed cell type in the adult lung and redifferentiate in response to injury.
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Pulmonary hypertension (PH), increased blood pressure in the pulmonary arteries, is a morbid and lethal disease. PH is classified into several groups based on etiology, but pathological remodeling of the pulmonary vasculature is a common feature. Endothelial cell dysfunction and excess smooth muscle cell proliferation and migration are central to the vascular pathogenesis. In addition, other cell types, including fibroblasts, pericytes, inflammatory cells and platelets contribute as well. Herein, we briefly note most of the main cell types active in PH and for each cell type, highlight select signaling pathway(s) highly implicated in that cell type in this disease. Among others, the role of hypoxia-inducible factors, growth factors (e.g., vascular endothelial growth factor, platelet-derived growth factor, transforming growth factor-ß and bone morphogenetic protein), vasoactive molecules, NOTCH3, Kruppel-like factor 4 and forkhead box proteins are discussed. Additionally, deregulated processes of endothelial-to-mesenchymal transition, extracellular matrix remodeling and intercellular crosstalk are noted. This brief review touches upon select critical facets of PH pathobiology and aims to incite further investigation that will result in discoveries with much-needed clinical impact for this devastating disease.
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Hipertensión Pulmonar , Humanos , Factor A de Crecimiento Endotelial Vascular/metabolismo , Músculo Liso Vascular/metabolismo , Células Cultivadas , Transducción de Señal , Arteria Pulmonar , Remodelación Vascular , Proliferación Celular , Miocitos del Músculo LisoRESUMEN
Aging is the predominant risk factor for atherosclerosis, the leading cause of death. Rare smooth muscle cell (SMC) progenitors clonally expand giving rise to up to ~70% of atherosclerotic plaque cells; however, the effect of age on SMC clonality is not known. Our results indicate that aged bone marrow (BM)-derived cells non-cell autonomously induce SMC polyclonality and worsen atherosclerosis. Indeed, in myeloid cells from aged mice and humans, TET2 levels are reduced which epigenetically silences integrin ß3 resulting in increased tumor necrosis factor [TNF]-α signaling. TNFα signals through TNF receptor 1 on SMCs to promote proliferation and induces recruitment and expansion of multiple SMC progenitors into the atherosclerotic plaque. Notably, integrin ß3 overexpression in aged BM preserves dominance of the lineage of a single SMC progenitor and attenuates plaque burden. Our results demonstrate a molecular mechanism of aged macrophage-induced SMC polyclonality and atherogenesis and suggest novel therapeutic strategies.
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Aterosclerosis , Placa Aterosclerótica , Humanos , Ratones , Animales , Anciano , Placa Aterosclerótica/metabolismo , Médula Ósea/metabolismo , Integrina beta3/metabolismo , Aterosclerosis/genética , Miocitos del Músculo Liso , Músculo Liso/metabolismoRESUMEN
Obstructive arterial diseases, including supravalvular aortic stenosis (SVAS), atherosclerosis, and restenosis, share 2 important features: an abnormal or disrupted elastic lamellae structure and excessive smooth muscle cells (SMCs). However, the relationship between these pathological features is poorly delineated. SVAS is caused by heterozygous loss-of-function, hypomorphic, or deletion mutations in the elastin gene (ELN), and SVAS patients and elastin-mutant mice display increased arterial wall cellularity and luminal obstructions. Pharmacological treatments for SVAS are lacking, as the underlying pathobiology is inadequately defined. Herein, using human aortic vascular cells, mouse models, and aortic samples and SMCs derived from induced pluripotent stem cells of ELN-deficient patients, we demonstrated that elastin insufficiency induced epigenetic changes, upregulating the NOTCH pathway in SMCs. Specifically, reduced elastin increased levels of γ-secretase, activated NOTCH3 intracellular domain, and downstream genes. Notch3 deletion or pharmacological inhibition of γ-secretase attenuated aortic hypermuscularization and stenosis in Eln-/- mutants. Eln-/- mice expressed higher levels of NOTCH ligand JAGGED1 (JAG1) in aortic SMCs and endothelial cells (ECs). Finally, Jag1 deletion in SMCs, but not ECs, mitigated the hypermuscular and stenotic phenotype in the aorta of Eln-/- mice. Our findings reveal that NOTCH3 pathway upregulation induced pathological aortic SMC accumulation during elastin insufficiency and provide potential therapeutic targets for SVAS.
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Estenosis Aórtica Supravalvular , Elastina , Proteína Jagged-1/metabolismo , Secretasas de la Proteína Precursora del Amiloide , Animales , Aorta/metabolismo , Estenosis Aórtica Supravalvular/genética , Estenosis Aórtica Supravalvular/metabolismo , Estenosis Aórtica Supravalvular/patología , Constricción Patológica , Elastina/genética , Elastina/metabolismo , Células Endoteliales/metabolismo , Humanos , Ratones , Receptor Notch3/genéticaRESUMEN
Cellular senescence and smooth muscle cells are key features of the atherosclerotic plaque; however, how senescent cells regulate smooth muscle cells is largely unknown. Herein, a new study in Nature Aging illuminates this interplay, providing insights into plaque dynamics and stability with potentially profound implications for heart attack and stroke.
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Aterosclerosis , Placa Aterosclerótica , Humanos , Senescencia Celular , Células Cultivadas , Miocitos del Músculo LisoRESUMEN
OBJECTIVE: The phenotypic plasticity of vascular smooth muscle cells (VSMCs) is central to vessel growth and remodeling, but also contributes to cardiovascular pathologies. New technologies including fate mapping, single cell transcriptomics, and genetic and pharmacologic inhibitors have provided fundamental new insights into the biology of VSMC. The goal of this review is to summarize the mechanisms underlying VSMC phenotypic modulation and how these might be targeted for therapeutic benefit. METHODS: We summarize findings from extensive literature searches to highlight recent discoveries in the mechanisms underlying VSMC phenotypic switching with particular relevance to intimal hyperplasia. PubMed was searched for publications between January 2001 and December 2020. Search terms included VSMCs, restenosis, intimal hyperplasia, phenotypic switching or modulation, and drug-eluting stents. We sought to highlight druggable pathways as well as recent landmark studies in phenotypic modulation. RESULTS: Lineage tracing methods have determined that a small number of mature VSMCs dedifferentiate to give rise to oligoclonal lesions in intimal hyperplasia and atherosclerosis. In atherosclerosis and aneurysm, single cell transcriptomics reveal a striking diversity of phenotypes that can arise from these VSMCs. Mechanistic studies continue to identify new pathways that influence VSMC phenotypic plasticity. We review the mechanisms by which the current drug-eluting stent agents prevent restenosis and note remaining challenges in peripheral and diabetic revascularization for which new approaches would be beneficial. We summarize findings on new epigenetic (DNA methylation/TET methylcytosine dioxygenase 2, histone deacetylation, bromodomain proteins), transcriptional (Hippo/Yes-associated protein, peroxisome proliferator-activity receptor-gamma, Notch), and ß3-integrin-mediated mechanisms that influence VSMC phenotypic modulation. Pharmacologic and genetic targeting of these pathways with agents including ascorbic acid, histone deacetylase or bromodomain inhibitors, thiazolidinediones, and integrin inhibitors suggests potential therapeutic value in the setting of intimal hyperplasia. CONCLUSIONS: Understanding the molecular mechanisms that underlie the remarkable plasticity of VSMCs may lead to novel approaches to treat and prevent cardiovascular disease and restenosis.
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During lung fibrosis, the epithelium induces signaling to underlying mesenchyme to generate excess myofibroblasts and extracellular matrix; herein, we focus on signaling in the mesenchyme. Our studies indicate that platelet-derived growth factor receptor (PDGFR)-ß+ cells are the predominant source of myofibroblasts and Kruppel-like factor (KLF) 4 is upregulated in PDGFR-ß+ cells, inducing TGFß pathway signaling and fibrosis. In fibrotic lung patches, KLF4 is down-regulated, suggesting KLF4 levels decrease as PDGFR-ß+ cells transition into myofibroblasts. In contrast to PDGFR-ß+ cells, KLF4 reduction in α-smooth muscle actin (SMA)+ cells non-cell autonomously exacerbates lung fibrosis by inducing macrophage accumulation and pro-fibrotic effects of PDGFR-ß+ cells via a Forkhead box M1 to C-C chemokine ligand 2-receptor 2 pathway. Taken together, in the context of lung fibrosis, our results indicate that KLF4 plays opposing roles in PDGFR-ß+ cells and SMA+ cells and highlight the importance of further studies of interactions between distinct mesenchymal cell types.
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Factor 4 Similar a Kruppel/genética , Factor 4 Similar a Kruppel/metabolismo , Pulmón/metabolismo , Células Madre Mesenquimatosas/metabolismo , Miofibroblastos/metabolismo , Animales , Proliferación Celular , Modelos Animales de Enfermedad , Regulación hacia Abajo , Matriz Extracelular/metabolismo , Femenino , Fibroblastos/metabolismo , Fibrosis , Humanos , Pulmón/patología , Lesión Pulmonar/metabolismo , Lesión Pulmonar/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Receptor beta de Factor de Crecimiento Derivado de Plaquetas/metabolismo , Enfermedades Respiratorias/metabolismo , Transducción de Señal , Factor de Crecimiento Transformador beta/metabolismoRESUMEN
Excess macrophages and smooth muscle cells (SMCs) characterize many cardiovascular diseases, but crosstalk between these cell types is poorly defined. Pulmonary hypertension (PH) is a lethal disease in which lung arteriole SMCs proliferate and migrate, coating the normally unmuscularized distal arteriole. We hypothesized that increased macrophage platelet-derived growth factor-B (PDGF-B) induces pathological SMC burden in PH. Our results indicate that clodronate attenuates hypoxia-induced macrophage accumulation, distal muscularization, PH, and right ventricle hypertrophy (RVH). With hypoxia exposure, macrophage Pdgfb mRNA was upregulated in mice, and LysMCre mice carrying floxed alleles for hypoxia-inducible factor 1a, hypoxia-inducible factor 2a, or Pdgfb had reduced macrophage Pdgfb and were protected against distal muscularization and PH. Conversely, LysMCre von-Hippel Lindaufl/fl mice had increased macrophage Hifa and Pdgfb and developed distal muscularization, PH, and RVH in normoxia. Similarly, Pdgfb was upregulated in macrophages from human idiopathic or systemic sclerosis-induced pulmonary arterial hypertension patients, and macrophage-conditioned medium from these patients increased SMC proliferation and migration via PDGF-B. Finally, in mice, orotracheal administration of nanoparticles loaded with Pdgfb siRNA specifically reduced lung macrophage Pdgfb and prevented hypoxia-induced distal muscularization, PH, and RVH. Thus, macrophage-derived PDGF-B is critical for pathological SMC expansion in PH, and nanoparticle-mediated inhibition of lung macrophage PDGF-B has profound implications as an interventional strategy for PH.
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Hipertensión Pulmonar/patología , Macrófagos/metabolismo , Músculo Liso/fisiopatología , Proteínas Proto-Oncogénicas c-sis/fisiología , Animales , Humanos , Hipertensión Pulmonar/metabolismo , Ratones , Músculo Liso/patologíaRESUMEN
Fibrosis is a macrophage-driven process of uncontrolled extracellular matrix accumulation. Neuronal guidance proteins such as netrin-1 promote inflammatory scarring. We found that macrophage-derived netrin-1 stimulates fibrosis through its neuronal guidance functions. In mice, fibrosis due to inhaled bleomycin engendered netrin-1-expressing macrophages and fibroblasts, remodeled adrenergic nerves, and augmented noradrenaline. Cell-specific knockout mice showed that collagen accumulation, fibrotic histology, and nerve-associated endpoints required netrin-1 of macrophage but not fibroblast origin. Adrenergic denervation; haploinsufficiency of netrin-1's receptor, deleted in colorectal carcinoma; and therapeutic α1 adrenoreceptor antagonism improved collagen content and histology. An idiopathic pulmonary fibrosis (IPF) lung microarray data set showed increased netrin-1 expression. IPF lung tissues were enriched for netrin-1+ macrophages and noradrenaline. A longitudinal IPF cohort showed improved survival in patients prescribed α1 adrenoreceptor blockade. This work showed that macrophages stimulate lung fibrosis via netrin-1-driven adrenergic processes and introduced α1 blockers as a potentially new fibrotic therapy.
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Pulmón/inervación , Pulmón/metabolismo , Macrófagos/metabolismo , Netrina-1/metabolismo , Fibrosis Pulmonar/metabolismo , Animales , Bleomicina/efectos adversos , Bleomicina/farmacología , Femenino , Pulmón/patología , Macrófagos/patología , Masculino , Ratones , Ratones Transgénicos , Netrina-1/genética , Norepinefrina/genética , Norepinefrina/metabolismo , Fibrosis Pulmonar/inducido químicamente , Fibrosis Pulmonar/genética , Fibrosis Pulmonar/patologíaRESUMEN
The vascular endothelium is a critical regulator of vascular function. Diverse stimuli such as proinflammatory cytokines and hemodynamic forces modulate endothelial phenotype and thereby impact on the development of vascular disease states. Therefore, identification of the regulatory factors that mediate the effects of these stimuli on endothelial function is of considerable interest. Transcriptional profiling studies identified the Kruppel-like factor (KLF)2 as being inhibited by the inflammatory cytokine interleukin-1beta and induced by laminar shear stress in cultured human umbilical vein endothelial cells. Overexpression of KLF2 in umbilical vein endothelial cells robustly induced endothelial nitric oxide synthase expression and total enzymatic activity. In addition, KLF2 overexpression potently inhibited the induction of vascular cell adhesion molecule-1 and endothelial adhesion molecule E-selectin in response to various proinflammatory cytokines. Consistent with these observations, in vitro flow assays demonstrate that T cell attachment and rolling are markedly attenuated in endothelial monolayers transduced with KLF2. Finally, our studies implicate recruitment by KLF2 of the transcriptional coactivator cyclic AMP response element-binding protein (CBP/p300) as a unifying mechanism for these various effects. These data implicate KLF2 as a novel regulator of endothelial activation in response to proinflammatory stimuli.
Asunto(s)
Endotelio Vascular/fisiología , Inflamación/fisiopatología , Transactivadores/fisiología , Transcripción Genética , Secuencia de Bases , Células Cultivadas , Cartilla de ADN , Selectina E/genética , Endotelio Vascular/fisiopatología , Regulación de la Expresión Génica/efectos de los fármacos , Glutatión Transferasa/genética , Humanos , Molécula 1 de Adhesión Intercelular/genética , Interleucina-1/farmacología , Factores de Transcripción de Tipo Kruppel , FN-kappa B/antagonistas & inhibidores , Óxido Nítrico Sintasa/genética , Óxido Nítrico Sintasa de Tipo III , Análisis de Secuencia por Matrices de Oligonucleótidos , Reacción en Cadena de la Polimerasa , Regiones Promotoras Genéticas , Estrés Mecánico , Transactivadores/antagonistas & inhibidores , Transactivadores/genética , Venas Umbilicales , Dedos de Zinc/fisiologíaRESUMEN
Pulmonary hypertension is a devastating disease characterized by excessive vascular muscularization. We previously demonstrated primed platelet-derived growth factor receptor ß+ (PDGFR-ß+)/smooth muscle cell (SMC) marker+ progenitors at the muscular-unmuscular arteriole border in the normal lung, and in hypoxia-induced pulmonary hypertension, a single primed cell migrates distally and expands clonally, giving rise to most of the pathological smooth muscle coating of small arterioles. Little is known regarding the molecular mechanisms underlying this process. Herein, we show that primed cell expression of Kruppel-like factor 4 and hypoxia-inducible factor 1-α (HIF1-α) are required, respectively, for distal migration and smooth muscle expansion in a sequential manner. In addition, the HIF1-α/PDGF-B axis in endothelial cells non-cell autonomously regulates primed cell induction, proliferation, and differentiation. Finally, myeloid cells transdifferentiate into or fuse with distal arteriole SMCs during hypoxia, and Pdgfb deletion in myeloid cells attenuates pathological muscularization. Thus, primed cell autonomous and non-cell autonomous pathways are attractive therapeutic targets for pulmonary hypertension.