RESUMO
Accumulation of excess cholesterol and cholesteryl ester in macrophage 'foam' cells within the arterial intima characterises early 'fatty streak' atherosclerotic lesions, and is accompanied by epigenetic changes, including altered expression of microRNA sequences which determine of gene and protein expression. This study established that exposure to lipoproteins, including acetylated LDL, induced macrophage expression of microRNA hsa-let-7d-5p, a sequence previously linked with tumour suppression, and repressed expression of one of its target genes, high mobility group AT hook 2 (HMGA2). A let-7d-5p mimic repressed expression of HMGA2 (18%; p < 0.05) while a marked increase (2.9-fold; p < 0.05) in expression of HMGA2 was noted in the presence of let-7d-5p inhibitor. Under these conditions, let-7d-5p mimic significantly (p < 0.05) decreased total (10%), free (8%) and cholesteryl ester (21%) mass, while the inhibitor significantly (p < 0.05) increased total (29%) and free cholesterol (29%) mass, compared with the relevant controls. Let-7d-5p inhibition significantly (p < 0.05) increased endogenous biosynthesis of cholesterol (38%) and cholesteryl ester (39%) pools in macrophage 'foam' cells, without altering the cholesterol efflux pathway, or esterification of exogenous radiolabelled oleate. Let-7d-5p inhibition in sterol-loaded cells increased the level of HMGA2 protein (32%; p < 0.05), while SiRNA knockdown of this protein (29%; p < 0.05) resulted in a (21%, p < 0.05) reduction in free cholesterol mass. Thus, induction of let-7d-5p, and repression of its target HMGA2, in macrophages is a protective response to the challenge of increased cholesterol influx into these cells; dysregulation of this response may contribute to atherosclerosis and other disorders such as cancer.
Assuntos
Proteína HMGA2/metabolismo , Lipoproteínas LDL/metabolismo , Macrófagos/metabolismo , MicroRNAs/metabolismo , Células Cultivadas , Humanos , Lipoproteínas LDL/análise , Macrófagos/citologia , MicroRNAs/genéticaRESUMO
Pulmonary hypertension is a serious clinical condition characterised by increased pulmonary arterial pressure. This can lead to right ventricular failure which can be fatal. Connexins are gap junction-forming membrane proteins which serve to exchange small molecules of less than 1 kD between cells. Connexins can also form hemi-channels connecting the intracellular and extracellular environments. Hemi-channels can mediate adenosine triphosphate release and are involved in autocrine and paracrine signalling. Recently, our group and others have identified evidence that connexin-mediated signalling may be involved in the pathogenesis of pulmonary hypertension. In this review, we discuss the evidence that dysregulated connexin-mediated signalling is associated with pulmonary hypertension.
Assuntos
Conexinas/metabolismo , Hipertensão Pulmonar/metabolismo , Transdução de Sinais , Animais , Modelos Animais de Doenças , Junções Comunicantes/metabolismo , Humanos , Hipertensão Pulmonar/patologiaRESUMO
Accumulation of macrophage "foam" cells, laden with cholesterol and cholesteryl ester, within the intima of large arteries, is a hallmark of early "fatty streak" lesions which can progress to complex, multicellular atheromatous plaques, involving lipoproteins from the bloodstream and cells of the innate and adaptive immune response. Sterol accumulation triggers induction of genes encoding proteins mediating the atheroprotective cholesterol efflux pathway. Within the arterial intima, however, this mechanism is overwhelmed, leading to distinct changes in macrophage phenotype and inflammatory status. Over the last decade marked gains have been made in understanding of the epigenetic landscape which influence macrophage function, and in particular the importance of small non-coding micro-RNA (miRNA) sequences in this context. This review identifies some of the miRNA sequences which play a key role in regulating "foam" cell formation and atherogenesis, highlighting sequences involved in cholesterol accumulation, those influencing inflammation in sterol-loaded cells, and novel sequences and pathways which may offer new strategies to influence macrophage function within atherosclerotic lesions.
RESUMO
Pulmonary hypertension (PH) is a disease associated with vasoconstriction and remodelling of the pulmonary vasculature. Pulmonary artery fibroblasts (PAFs) play an important role in hypoxic-induced remodelling. Connexin 43 (Cx43) is involved in cellular communication and regulation of the pulmonary vasculature. Using both in vitro and in vivo models of PH, the aims of this study were to (i) investigate the role of Cx43 in hypoxic-induced proliferation and migration of rat PAFs (rPAFs) and rat pulmonary artery smooth muscle cells (rPASMCs) and (ii) determine whether Cx43 expression is dysregulated in the rat sugen5416/hypoxic model of PH. The role of Cx43 in hypoxic-induced proliferation and migration was investigated using Gap27 (a pharmacological inhibitor of Cx43) or genetic knockdown of Cx43 using siRNA. Cx43 protein expression was increased by hypoxia in rPAFs but not rPASMCs. Hypoxic exposure, in the presence of serum, resulted in an increase in proliferation of rPAFs but not rPASMCs. Hypoxic exposure caused migration of rPAFs but not rPASMCs. Phosphorylation of p38 mitogen-activated protein kinase (MAPK) and ERK1/2 were increased by hypoxia in rPAFs. The effects of hypoxia on proliferation, migration and MAPK phosphorylation in rPAFs were attenuated in the presence of Gap27 or Cx43 siRNA. Cx43 protein expression was increased in sugen5416/hypoxic rat lung; this increased expression was not observed in sugen5416/hypoxic rats treated with the MAPK pathway inhibitor GS-444217. In conclusion, Cx43 is involved in the proliferation and migration of rPAFs in response to hypoxia via the MAPK signalling pathway.
RESUMO
Pulmonary arterial hypertension (PAH) is a chronic condition characterized by vascular remodeling and increased vaso-reactivity. PAH is more common in females than in males (~3:1). Connexin (Cx)43 has been shown to be involved in cellular communication within the pulmonary vasculature. Therefore, we investigated the role of Cx43 in pulmonary vascular reactivity using Cx43 heterozygous (Cx43+/−) mice and 37,43Gap27, which is a pharmacological inhibitor of Cx37 and Cx43. Contraction and relaxation responses were studied in intra-lobar pulmonary arteries (IPAs) derived from normoxic mice and hypoxic mice using wire myography. IPAs from male Cx43+/− mice displayed a small but significant increase in the contractile response to endothelin-1 (but not 5-hydroxytryptamine) under both normoxic and hypoxic conditions. There was no difference in the contractile response to endothelin-1 (ET-1) or 5-hydroxytryptamine (5-HT) in IPAs derived from female Cx43+/−mice compared to wildtype mice. Relaxation responses to methacholine (MCh) were attenuated in IPAs from male and female Cx43+/− mice or by pre-incubation of IPAs with 37,43Gap27. Nω-Nitro-L-arginine methyl ester (l-NAME) fully inhibited MCh-induced relaxation. In conclusion, Cx43 is involved in nitric oxide (NO)-induced pulmonary vascular relaxation and plays a gender-specific and agonist-specific role in pulmonary vascular contractility. Therefore, reduced Cx43 signaling may contribute to pulmonary vascular dysfunction.
Assuntos
Conexina 43/metabolismo , Artéria Pulmonar/metabolismo , Animais , Conexina 43/genética , Endotelina-1/metabolismo , Feminino , Junções Comunicantes/efeitos dos fármacos , Junções Comunicantes/metabolismo , Genótipo , Hipertensão Pulmonar/metabolismo , Isoproterenol/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Relaxamento Muscular/efeitos dos fármacos , Óxido Nítrico/metabolismo , Artéria Pulmonar/efeitos dos fármacos , Reação em Cadeia da Polimerase em Tempo Real , Serotonina/metabolismoRESUMO
Pulmonary arterial hypertension (PAH) is a complex, multi-factorial disorder characterized by both constriction and remodelling of the distal pulmonary vasculature. This leads to increased pulmonary pressures and eventually right heart failure. Current drugs, which primarily target the vasoconstriction, serve only to prolong life and novel therapies targeting both the vasoconstriction and the remodelling are required. Aberrant signalling between cells of the pulmonary vasculature has been associated with the development of PAH. In particular, endothelial dysfunction can lead to hyperplasia of the underlying medial layer. Connexins are a family of transmembrane proteins which can form intercellular communication channels known as gap junctions. This review will discuss recent evidence which shows that connexins play a role in regulation of the pulmonary vasculature and that dysregulation of connexins may contribute to PAH pathogenesis. Interaction of connexins with signalling pathways relevant to the pathogenesis of PAH, such as bone morphogenetic protein (BMP), serotonin and oestrogen are discussed.
Assuntos
Conexinas/metabolismo , Insuficiência Cardíaca/genética , Hipertensão Pulmonar/metabolismo , Artéria Pulmonar/metabolismo , Proteínas Morfogenéticas Ósseas/metabolismo , Comunicação Celular/genética , Conexinas/genética , Estrogênios/metabolismo , Junções Comunicantes/genética , Insuficiência Cardíaca/fisiopatologia , Humanos , Hipertensão Pulmonar/genética , Hipertensão Pulmonar/fisiopatologia , Artéria Pulmonar/fisiopatologia , Serotonina/metabolismo , Transdução de Sinais/genética , Vasoconstrição/genéticaRESUMO
AIMS: Pulmonary arterial hypertension (PAH) occurs more frequently in women with mutations in bone morphogenetic protein receptor type 2 (BMPR2) and dysfunctional BMPR2 signalling underpinning heritable PAH. We have previously shown that serotonin can uncover a pulmonary hypertensive phenotype in BMPR2(+/-) mice and that oestrogen can increase serotinergic signalling in human pulmonary arterial smooth muscle cells (hPASMCs). Hence, here we wished to characterize the expression of oestrogen receptors (ERs) in male and female human pulmonary arteries and have examined the influence of oestrogen and serotonin on BMPR2 and ERα expression. METHODS AND RESULTS: By immunohistochemistry, we showed that ERα, ERß, and G-protein-coupled receptors are expressed in human pulmonary arteries localizing mainly to the smooth muscle layer which also expresses the serotonin transporter (SERT). Protein expression of ERα protein was higher in female PAH patient hPASMCs compared with male and serotonin also increased the expression of ERα. 17ß-estradiol induced proliferation of hPASMCs via ERα activation and this engaged mitogen-activated protein kinase and Akt signalling. Female mice over-expressing SERT (SERT(+) mice) develop PH and the ERα antagonist MPP attenuated the development of PH in normoxic and hypoxic female SERT(+) mice. The therapeutic effects of MPP were accompanied by increased expression of BMPR2 in mouse lung. CONCLUSION: ERα is highly expressed in female hPASMCs from PAH patients and mediates oestrogen-induced proliferation of hPASMCs via mitogen-activated protein kinase and Akt signalling. Serotonin can increase ERα expression in hPASMCs and antagonism of ERα reverses serotonin-dependent PH in the mouse and increases BMPR2 expression.
Assuntos
Receptores de Proteínas Morfogenéticas Ósseas Tipo II/genética , Receptores de Proteínas Morfogenéticas Ósseas Tipo II/metabolismo , Receptor alfa de Estrogênio/metabolismo , Hipertensão Pulmonar/metabolismo , Proteínas da Membrana Plasmática de Transporte de Serotonina/metabolismo , Animais , Proliferação de Células/fisiologia , Modelos Animais de Doenças , Humanos , Hipertensão Pulmonar/genética , Hipertensão Pulmonar/patologia , Pulmão/metabolismo , Camundongos , Miócitos de Músculo Liso/metabolismoRESUMO
Pulmonary endothelial cell apoptosis is a transient, yet defining pathogenic event integral to the onset of many pulmonary vascular diseases such as pulmonary hypertension (PH). However, there is a paucity of information concerning the molecular pathway(s) that control pulmonary arterial endothelial cell apoptosis. Here, we introduce a molecular axis that when functionally active seems to induce pulmonary arterial endothelial cell apoptosis in vitro and PH in vivo. In response to apoptotic stimuli, human pulmonary arterial endothelial cells exhibited robust induction of a programmed cell death 4 (PDCD4)/caspase-3/apoptotic pathway that was reversible by direct PDCD4 silencing. Indirectly, this pathway was also repressed by delivery of a microRNA-21 mimic. In vivo, genetic deletion of microRNA-21 in mice (miR-21(-/-) mice) resulted in functional activation of the PDCD4/caspase-3 axis in the pulmonary tissues, leading to the onset of progressive PH. Conversely, microRNA-21-overexpressing mice (CAG-microRNA-21 mice) exhibited reduced PDCD4 expression in pulmonary tissues and were partially resistant to PH in response to chronic hypoxia plus SU 5416 injury. Furthermore, direct PDCD4 knockout in mice (PDCD4(-/-) mice) potently blocked pulmonary caspase-3 activation and the development of chronic hypoxia plus SU 5416 PH, confirming its importance in disease onset. Broadly, these findings support the existence of a microRNA-21-responsive PDCD4/caspase-3 pathway in the pulmonary tissues that when active serves to promote endothelial apoptosis in vitro and PH in vivo.
Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Apoptose/fisiologia , Caspase 3/metabolismo , Células Endoteliais/metabolismo , Hipertensão Pulmonar/metabolismo , MicroRNAs/metabolismo , Proteínas de Ligação a RNA/metabolismo , Animais , Linhagem Celular Tumoral , Proliferação de Células , Humanos , Camundongos , MicroRNAs/genéticaRESUMO
Pulmonary arterial hypertension (PAH) is a progressive disease in which increased pulmonary arterial pressure and remodelling eventually lead to right heart failure and death. Idiopathic and familial PAH occur far more frequently in women than in men. Historically, investigations into this gender bias have been impeded because female gender and oestrogens paradoxically protect against PAH in commonly used rodent models. However, recent descriptions of female gender-specific murine models of PAH have led to an increased understanding of the role of oestrogens in disease development. Specifically, oestrogen metabolism has been highlighted as playing an important role in disease development, and the oestrogen-metabolizing enzyme CYP1B1 may represent a novel therapeutic target. In addition, emerging evidence suggests that sex hormones may have direct effects on the right ventricle independent of haemodynamic effects. This review discusses our current understanding of the role of sex hormones in the development of PAH.
Assuntos
Hipertensão Pulmonar/etiologia , Hipertensão Pulmonar/fisiopatologia , Artéria Pulmonar/fisiopatologia , Animais , Hipertensão Pulmonar Primária Familiar , Hormônios Esteroides Gonadais/metabolismo , Ventrículos do Coração/fisiopatologia , Hemodinâmica/fisiologia , Humanos , Hipertensão Pulmonar/metabolismo , Artéria Pulmonar/metabolismo , Fatores SexuaisRESUMO
AIMS: Pulmonary arterial hypertension (PAH) occurs more frequently in women than men. Oestrogen and the oestrogen-metabolising enzyme cytochrome P450 1B1 (CYP1B1) play a role in the development of PAH. Anorectic drugs such as dexfenfluramine (Dfen) have been associated with the development of PAH. Dfen mediates PAH via a serotonergic mechanism and we have shown serotonin to up-regulate expression of CYP1B1 in human pulmonary artery smooth muscle cells (PASMCs). Thus here we assess the role of CYP1B1 in the development of Dfen-induced PAH. METHODS AND RESULTS: Dfen (5 mg kg(-1) day(-1) PO for 28 days) increased right ventricular pressure and pulmonary vascular remodelling in female mice only. Mice dosed with Dfen showed increased whole lung expression of CYP1B1 and Dfen-induced PAH was ablated in CYP1B1(-/-) mice. In line with this, Dfen up-regulated expression of CYP1B1 in PASMCs from PAH patients (PAH-PASMCs) and Dfen-mediated proliferation of PAH-PASMCs was ablated by pharmacological inhibition of CYP1B1. Dfen increased expression of tryptophan hydroxylase 1 (Tph1; the rate-limiting enzyme in the synthesis of serotonin) in PAH-PASMCs and both Dfen-induced proliferation and Dfen-induced up-regulation of CYP1B1 were ablated by inhibition of Tph1. 17ß-Oestradiol increased expression of both Tph1 and CYP1B1 in PAH-PASMCs, and Dfen and 17ß-oestradiol had synergistic effects on proliferation of PAH-PASMCs. Finally, ovariectomy protected against Dfen-induced PAH in female mice. CONCLUSION: CYP1B1 is critical in the development of Dfen-induced PAH in mice in vivo and proliferation of PAH-PASMCs in vitro. CYP1B1 may provide a novel therapeutic target for PAH.
Assuntos
Hidrocarboneto de Aril Hidroxilases/metabolismo , Dexfenfluramina , Hipertensão Pulmonar/enzimologia , Músculo Liso Vascular/enzimologia , Miócitos de Músculo Liso/enzimologia , Animais , Pressão Arterial , Hidrocarboneto de Aril Hidroxilases/antagonistas & inibidores , Hidrocarboneto de Aril Hidroxilases/deficiência , Hidrocarboneto de Aril Hidroxilases/genética , Proliferação de Células , Células Cultivadas , Citocromo P-450 CYP1B1 , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/farmacologia , Estradiol/farmacologia , Hipertensão Pulmonar Primária Familiar , Feminino , Hipertensão Pulmonar/induzido quimicamente , Hipertensão Pulmonar/genética , Hipertensão Pulmonar/patologia , Hipertensão Pulmonar/fisiopatologia , Hipertensão Pulmonar/prevenção & controle , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Músculo Liso Vascular/efeitos dos fármacos , Músculo Liso Vascular/patologia , Músculo Liso Vascular/fisiopatologia , Miócitos de Músculo Liso/efeitos dos fármacos , Miócitos de Músculo Liso/patologia , Norfenfluramina/toxicidade , Ovariectomia , Artéria Pulmonar/enzimologia , Artéria Pulmonar/fisiopatologia , Serotonina/metabolismo , Fatores Sexuais , Triptofano Hidroxilase/metabolismo , Função Ventricular Direita , Pressão VentricularRESUMO
MicroRNAs are small noncoding RNAs involved in the regulation of gene expression and have recently been implicated in the development of pulmonary arterial hypertension (PAH). Previous work has established that miR-451 is upregulated in rodent models of PAH. The role of miR-451 in the pulmonary circulation is unknown. We therefore sought to assess the involvement of miR-451 in the development of PAH. Silencing of miR-451 was performed in vivo using miR-451 knockout mice and an anti-miR targeting mature miR-451 in rats. Coupled with exposure to hypoxia, indices of PAH were assessed. The effect of modulating miR-451 on human pulmonary artery smooth muscle cell proliferation and migration was analyzed. We observed a reduction in systolic right ventricular pressure in hypoxic rats pretreated with anti-miR-451 compared with hypoxia alone ([Formula: see text] mmHg and [Formula: see text] mmHg, respectively; [Formula: see text]). In miR-451 knockout mice, compared with wild-type hypoxic mice, no significant differences were observed following exposure to chronic hypoxia. In vitro analysis demonstrated that overexpression of miR-451 in human pulmonary artery smooth muscle cells promoted migration under serum-free conditions. No effect on cellular proliferation was observed. In conclusion, transient inhibition of miR-451 attenuated the development of PAH in hypoxia-exposed rats. Genetic deletion of miR-451 had no beneficial effect on indices of PAH, potentially because of pathway redundancy compensating for the loss of miR-451.
RESUMO
RATIONALE: Despite improved understanding of the underlying genetics, pulmonary arterial hypertension (PAH) remains a severe disease. Extensive remodeling of small pulmonary arteries, including proliferation of pulmonary artery smooth muscle cells (PASMCs), characterizes PAH. MicroRNAs (miRNAs) are noncoding RNAs that have been shown to play a role in vascular remodeling. OBJECTIVE: We assessed the role of miR-145 in PAH. METHODS AND RESULTS: We localized miR-145 in mouse lung to smooth muscle. Using quantitative PCR, we demonstrated increased expression of miR-145 in wild-type mice exposed to hypoxia. PAH was evaluated in miR-145 knockout and mice treated with anti-miRs via measurement of systolic right ventricular pressure, right ventricular hypertrophy, and percentage of remodeled pulmonary arteries. miR-145 deficiency and anti-miR-mediated reduction resulted in significant protection from the development of PAH. In contrast, miR-143 anti-miR had no effect. Furthermore, we observed upregulation of miR-145 in lung tissue of patients with idiopathic and heritable PAH compared with unaffected control subjects and demonstrated expression of miR-145 in SMC of remodeled vessels from such patients. Finally, we show elevated levels of miR-145 expression in primary PASMCs cultured from patients with BMPR2 mutations and also in the lungs of BMPR2-deficient mice. CONCLUSIONS: miR-145 is dysregulated in mouse models of PAH. Downregulation of miR-145 protects against the development of PAH. In patient samples of heritable PAH and idiopathic PAH, miR-145 is expressed in remodeled vessels and mutations in BMPR2 lead to upregulation of miR-145 in mice and PAH patients. Manipulation of miR-145 may represent a novel strategy in PAH treatment.
Assuntos
Modelos Animais de Doenças , Hipertensão Pulmonar/genética , Hipertensão Pulmonar/patologia , MicroRNAs/fisiologia , Animais , Regulação para Baixo/genética , Feminino , Técnicas de Introdução de Genes , Humanos , Hipertensão Pulmonar/prevenção & controle , Pulmão/patologia , Pulmão/fisiologia , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , MicroRNAs/antagonistas & inibidores , MicroRNAs/genéticaRESUMO
BACKGROUND: Idiopathic and familial forms of pulmonary arterial hypertension (PAH) occur more frequently in women than men. However, the reason for this remains unknown. Both the calcium binding protein S100A4/Mts1 (Mts1) and its endogenous receptor (receptor for advanced glycosylation end products; RAGE) have been implicated in the development of PAH. We wished to investigate if the Mts1/RAGE pathway may play a role in the gender bias associated with PAH. METHODS: We investigated the effects of gender on development of PAH in mice over-expressing Mts1 (Mts1+ mice) via measurement of pulmonary arterial remodeling, systolic right ventricular pressure (sRVP) and right ventricular hypertrophy (RVH). Gender differences in pulmonary arterial Mts1 and RAGE expression were assessed by qRT-PCR and immunohistochemistry. Western blotting and cell counts were used to investigate interactions between 17ß-estradiol, Mts1 and RAGE on proliferation of human pulmonary artery smooth muscle cells (hPASMCs). Statistical analysis was by one-way analysis of variance with Dunnetts post test or two-way analysis of variance with Bonferronis post test, as appropriate. RESULTS: Female Mts1+ mice developed increased sRVP and pulmonary vascular remodeling, whereas male Mts1+ mice remained unaffected. The development of plexiform-like lesions in Mts1+ mice was specific to females. These lesions stained positive for both Mts1 and RAGE in the endothelial and adventitial layers. Expression of pulmonary arterial Mts1 was greater in female than male Mts1+ mice, and was localised to the medial and adventitial layers in non plexiform-like pulmonary arteries. RAGE gene expression and immunoreactivity were similar between male and female Mts1+ mice and RAGE staining was localised to the endothelial layer in non plexiform-like pulmonary arteries adjacent to airways. In non-plexiform like pulmonary arteries not associated with airways RAGE staining was present in the medial and adventitial layers. Physiological concentrations of 17ß-estradiol increased Mts1 expression in hPASMCs. 17ß-estradiol-induced hPASMC proliferation was inhibited by soluble RAGE, which antagonises the membrane bound form of RAGE. CONCLUSIONS: Mts1 over-expression combined with female gender is permissive to the development of experimental PAH in mice. Up-regulation of Mts1 and subsequent activation of RAGE may contribute to 17ß-estradiol-induced proliferation of hPASMCs.
Assuntos
Pressão Sanguínea , Hipertensão Pulmonar/metabolismo , Artéria Pulmonar/metabolismo , Proteínas S100/metabolismo , Análise de Variância , Animais , Pressão Sanguínea/genética , Western Blotting , Proliferação de Células , Células Cultivadas , Modelos Animais de Doenças , Estradiol/metabolismo , Hipertensão Pulmonar Primária Familiar , Feminino , Predisposição Genética para Doença , Hipertensão Pulmonar/genética , Hipertensão Pulmonar/patologia , Hipertensão Pulmonar/fisiopatologia , Hipertrofia Ventricular Direita/genética , Hipertrofia Ventricular Direita/metabolismo , Imuno-Histoquímica , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CBA , Camundongos Transgênicos , Músculo Liso Vascular/metabolismo , Músculo Liso Vascular/patologia , Miócitos de Músculo Liso/metabolismo , Miócitos de Músculo Liso/patologia , Fenótipo , Artéria Pulmonar/patologia , Artéria Pulmonar/fisiopatologia , Reação em Cadeia da Polimerase em Tempo Real , Receptor para Produtos Finais de Glicação Avançada , Receptores Imunológicos/genética , Receptores Imunológicos/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteína A4 de Ligação a Cálcio da Família S100 , Proteínas S100/genética , Fatores Sexuais , Transdução de Sinais , Regulação para Cima , Função Ventricular Direita , Pressão VentricularRESUMO
Pulmonary arterial hypertension (PAH) is up to threefold more prevalent in women than men. Female mice overexpressing the serotonin transporter (SERT; SERT+ mice) exhibit PAH and exaggerated hypoxia-induced PAH, whereas male SERT+ mice remain unaffected. To further investigate these sex differences, microarray analysis was performed in the pulmonary arteries of normoxic and chronically hypoxic female and male SERT+ mice. Quantitative RT-PCR analysis was employed for validation of the microarray data. In relevant groups, immunoblotting was performed for genes of interest (CEBPß, CYP1B1, and FOS). To translate clinical relevance to our findings, CEBPß, CYP1B1, and FOS mRNA and protein expression was assessed in pulmonary artery smooth muscle cells (PASMCs) derived from idiopathic PAH (IPAH) patients and controls. In female SERT+ mice, multiple pathways with relevance to PAH were altered. This was also observed in chronically hypoxic female SERT+ mice. We selected 10 genes of interest for qRT-PCR analysis (FOS, CEBPß, CYP1B1, MYL3, HAMP2, LTF, PLN, NPPA, UCP1, and C1S), and 100% concordance was reported. Protein expression of three selected genes, CEBPß, CYP1B1, FOS, was also upregulated in female SERT+ mice. Serotonin and 17ß-estradiol increased CEBPß, CYP1B1, and FOS protein expression in PASMCs. In addition, CEBPß, CYP1B1, and FOS mRNA and protein expression was also increased in PASMCs derived from IPAH patients. Here, we have identified a number of genes that may predispose female SERT+ mice to PAH, and these findings may also be relevant to human PAH.
Assuntos
Hipóxia/complicações , Análise em Microsséries/métodos , Miócitos de Músculo Liso/metabolismo , Artéria Pulmonar/metabolismo , Proteínas da Membrana Plasmática de Transporte de Serotonina/genética , Proteínas da Membrana Plasmática de Transporte de Serotonina/metabolismo , Animais , Animais Geneticamente Modificados/genética , Hidrocarboneto de Aril Hidroxilases/metabolismo , Proteína beta Intensificadora de Ligação a CCAAT/metabolismo , Técnicas de Cultura de Células , Doença Hepática Crônica Induzida por Substâncias e Drogas , Citocromo P-450 CYP1B1 , Estrogênios/genética , Hipertensão Pulmonar Primária Familiar , Feminino , Expressão Gênica , Perfilação da Expressão Gênica , Humanos , Hipertensão Pulmonar/genética , Masculino , Camundongos , Proteínas Proto-Oncogênicas c-fes/metabolismo , SexoRESUMO
AIMS: Idiopathic and familial forms of pulmonary arterial hypertension (PAH) predominantly affect females through an unknown mechanism. Activity of the serotonin transporter (SERT) may modulate the development of PAH, and mice overexpressing SERT (SERT+ mice) develop PAH and severe hypoxia-induced PAH. In the central nervous system, oestrogens influence activity of the serotonin system. Therefore, we examined the influence of gender on the development of PAH in SERT+ mice and how this is modulated by female hormones. METHODS AND RESULTS: PAH was assessed via measurement of right ventricular systolic pressure (RVSP), pulmonary vascular remodelling (PVR), and right ventricular hypertrophy. Male SERT+ mice did not develop PAH. Female SERT+ mice demonstrated increased RVSP and PVR and this was abolished by ovariectomy. Following exposure to hypoxia, SERT+ mice exhibited severe PAH and this was also attenuated by ovariectomy. Chronic administration of 17ß oestradiol re-established the PAH phenotype in ovariectomized, normoxic, and hypoxic SERT+ mice. 17ß oestradiol also up-regulated tryptophan hydroxylase-1 (TPH1), 5-hydroytryptamine(1B) (5-HT(1B)) receptor, and SERT expression in human pulmonary arterial smooth muscle cells (hPASMCs). 17ß oestradiol stimulated hPASMC proliferation and this was inhibited by both the TPH inhibitor para-chlorophenylalanine and the 5-HT(1B) receptor antagonist SB224289. CONCLUSION: 17ß oestradiol is critical to the development of PAH and severe hypoxia-induced PAH in female SERT+ mice. In hPASMCs, 17ß oestradiol-induced proliferation is dependant on de novo serotonin synthesis and stimulation of the 5-HT(1B) receptor. These interactions between the serotonin system and 17ß oestradiol may contribute to the increased risk of PAH associated with female gender.
Assuntos
Estradiol/metabolismo , Hipóxia/fisiopatologia , Proteínas da Membrana Plasmática de Transporte de Serotonina/metabolismo , Animais , Divisão Celular/efeitos dos fármacos , Divisão Celular/fisiologia , Células Cultivadas , Estradiol/farmacologia , Hipertensão Pulmonar Primária Familiar , Feminino , Humanos , Hipertensão Pulmonar/epidemiologia , Hipertensão Pulmonar/metabolismo , Hipertensão Pulmonar/fisiopatologia , Hipóxia/epidemiologia , Hipóxia/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CBA , Camundongos Mutantes , Músculo Liso Vascular/citologia , Músculo Liso Vascular/efeitos dos fármacos , Ovariectomia , Fenótipo , Artéria Pulmonar/citologia , Artéria Pulmonar/efeitos dos fármacos , Receptor 5-HT1B de Serotonina/metabolismo , Fatores de Risco , Serotonina/metabolismo , Proteínas da Membrana Plasmática de Transporte de Serotonina/genética , Distribuição por SexoRESUMO
The serotonin hypothesis of pulmonary arterial hypertension (PAH) arose after an outbreak of PAH in patients taking the anorexigenic drugs aminorex and dexfenfluramine. Both of these drugs are serotonin transporter (SERT) substrates and indirect serotinergic agonists. There is now a wealth of evidence to support a role for serotonin in the pathobiology of PAH. Synthesis of serotonin can occur in pulmonary artery endothelial cells by the enzyme tryptophan hydroxylase 1 (TPH1). Serotonin then acts at the 5-HT(1B) receptor and the SERT to mediate constriction and proliferation of pulmonary artery smooth muscle cells. Downstream signalling molecules which play a role in serotonin-induced constriction and proliferation include reactive oxygen species (ROS), Rho-kinase (ROCK) p38 and extracellular signal-regulated kinase (ERK). There is also evidence to suggest that serotonin may interact with the bone morphogenetic receptor type II (BMPRII) to provide a 'second hit' risk factor for PAH.
Assuntos
Hipertensão Pulmonar/fisiopatologia , Serotonina/metabolismo , Animais , Depressores do Apetite/efeitos adversos , Depressores do Apetite/metabolismo , Receptores de Proteínas Morfogenéticas Ósseas Tipo II/genética , Receptores de Proteínas Morfogenéticas Ósseas Tipo II/metabolismo , Dexfenfluramina/efeitos adversos , Dexfenfluramina/metabolismo , Células Endoteliais/citologia , Células Endoteliais/metabolismo , Humanos , Hipertensão Pulmonar/induzido quimicamente , Pulmão/irrigação sanguínea , Pulmão/metabolismo , Pulmão/patologia , Receptores de Serotonina/metabolismo , Proteínas da Membrana Plasmática de Transporte de Serotonina/metabolismo , Agonistas do Receptor de Serotonina/efeitos adversos , Agonistas do Receptor de Serotonina/metabolismo , Transdução de Sinais/fisiologia , Vasoconstrição/fisiologiaRESUMO
OBJECTIVE: MicroRNAs (miRNAs) are small noncoding RNAs that have the capacity to control protein production through binding "seed" sequences within a target mRNA. Each miRNA is capable of potentially controlling hundreds of genes. The regulation of miRNAs in the lung during the development of pulmonary arterial hypertension (PAH) is unknown. METHODS AND RESULTS: We screened lung miRNA profiles in a longitudinal and crossover design during the development of PAH caused by chronic hypoxia or monocrotaline in rats. We identified reduced expression of Dicer, involved in miRNA processing, during the onset of PAH after hypoxia. MiR-22, miR-30, and let-7f were downregulated, whereas miR-322 and miR-451 were upregulated significantly during the development of PAH in both models. Differences were observed between monocrotaline and chronic hypoxia. For example, miR-21 and let-7a were significantly reduced only in monocrotaline-treated rats. MiRNAs that were significantly regulated were validated by quantitative polymerase chain reaction. By using in vitro studies, we demonstrated that hypoxia and growth factors implicated in PAH induced similar changes in miRNA expression. Furthermore, we confirmed miR-21 downregulation in human lung tissue and serum from patients with idiopathic PAH. CONCLUSIONS: Defined miRNAs are regulated during the development of PAH in rats. Therefore, miRNAs may contribute to the pathogenesis of PAH and represent a novel opportunity for therapeutic intervention.
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Perfilação da Expressão Gênica , Hipertensão Pulmonar/genética , Hipóxia/genética , Pulmão/metabolismo , MicroRNAs/metabolismo , Animais , Hipóxia Celular , Células Cultivadas , Doença Crônica , Modelos Animais de Doenças , Células Endoteliais/metabolismo , Fibroblastos/metabolismo , Perfilação da Expressão Gênica/métodos , Humanos , Hipertensão Pulmonar/induzido quimicamente , Hipóxia/complicações , Pulmão/irrigação sanguínea , Masculino , MicroRNAs/sangue , Monocrotalina , Músculo Liso Vascular/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , Ratos , Ratos Sprague-Dawley , Reprodutibilidade dos Testes , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Ribonuclease III/genética , Fatores de TempoRESUMO
AIMS: A mechanism for co-operation between the serotonin (5-hydroxytryptamine, 5-HT) transporter and 5-HT1B receptor in mediating pulmonary artery vasoconstriction and proliferation of pulmonary artery smooth muscle cells has been demonstrated in vitro. Here we determine, for the first time, the in vivo effects of a combined 5-HT1B receptor/serotonin transporter antagonist (LY393558) with respect to the development of pulmonary arterial hypertension (PAH) and its in vitro effects in human pulmonary artery smooth muscle cells (hPASMCs) derived from idiopathic PAH (IPAH) patients. METHODS AND RESULTS: We determined the effects of LY393558 as well as a selective serotonin transporter inhibitor, citalopram, on right ventricular pressure, right ventricular hypertrophy, and pulmonary vascular remodelling in wildtype mice and mice over-expressing serotonin transporter (SERT+ mice) before and after hypoxic exposure. We also compared their effectiveness at reversing PAH in SERT+ mice and hypoxic mice. Further, we examined the proliferative response to serotonin in IPAH hPASMCs. We also clarified the pharmacology of serotonin-induced vasoconstriction and 5-HT1B receptor/serotonin transporter interactions in mouse isolated pulmonary artery. Citalopram had a moderate effect at preventing and reversing experimental PAH in vivo whereas LY393558 was more effective. LY393558 was more effective than citalopram at reversing serotonin-induced proliferation in IPAH hPASMCs. There is synergy between 5-HT1B receptor and serotonin transporter inhibitors against serotonin-induced vasoconstriction in mouse pulmonary arteries. CONCLUSION: 5-HT1B receptor and serotonin transporter inhibition are effective at preventing and reversing experimental PAH and serotonin-induced proliferation of PASMCs derived from IPAH patients. Targeting both the serotonin transporter and 5-HT1B receptor may be a novel therapeutic approach to PAH.
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Citalopram/administração & dosagem , Óxidos S-Cíclicos/administração & dosagem , Hipertensão Pulmonar/tratamento farmacológico , Inibidores Seletivos de Recaptação de Serotonina/administração & dosagem , Antagonistas do Receptor 5-HT1 de Serotonina , Tiadiazinas/administração & dosagem , Animais , Proliferação de Células/efeitos dos fármacos , Feminino , Hipertensão Pulmonar/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CBA , Vasoconstrição/efeitos dos fármacosRESUMO
The serotonin hypothesis of pulmonary arterial hypertension (PAH) arose owing to anorexigens, acting as indirect serotinergic agonists, causing PAH. However, it is now thought that serotonin plays an important role in the pathobiology of PAH per se. The rate-limiting enzyme in the synthesis of peripheral serotonin is tryptophan hydroxylase 1 (TPH1), serotonin can mediate pulmonary arterial smooth muscle cell proliferation via the serotonin transporter (SERT) and serotonin can induce pulmonary vasoconstriction via the 5-HT1B receptor in man. There is evidence that TPH1, SERT and 5-HT1B expression/activity can be upregulated in clinical PAH. This review discusses recent evidence implicating serotonin in the development of experimental and clinical PAH and suggests potential therapeutic targets.
Assuntos
Hipertensão Pulmonar/fisiopatologia , Receptor 5-HT1B de Serotonina/metabolismo , Serotonina/metabolismo , Animais , Sistemas de Liberação de Medicamentos , Humanos , Hipertensão Pulmonar/etiologia , Hipertensão Pulmonar/genética , Músculo Liso Vascular/metabolismo , Artéria Pulmonar/metabolismo , Receptor 5-HT1B de Serotonina/genética , Proteínas da Membrana Plasmática de Transporte de Serotonina/genética , Proteínas da Membrana Plasmática de Transporte de Serotonina/metabolismo , Agonistas do Receptor de Serotonina/efeitos adversos , Triptofano Hidroxilase/genética , Triptofano Hidroxilase/metabolismo , Regulação para Cima , VasoconstriçãoRESUMO
BACKGROUND: The incidence of pulmonary arterial hypertension secondary to the use of indirect serotinergic agonists such as aminorex and dexfenfluramine led to the "serotonin hypothesis" of pulmonary arterial hypertension; however, the role of serotonin in dexfenfluramine-induced pulmonary arterial hypertension remains controversial. Here, we used novel transgenic mice lacking peripheral serotonin (deficient in tryptophan hydroxylase-1; Tph1(-/-) mice) or overexpressing the gene for the human serotonin transporter (SERT; SERT(+) mice) to investigate this further. METHODS AND RESULTS: Dexfenfluramine administration (5 mg x kg(-1) x d(-1) PO for 28 days) increased systolic right ventricular pressure and pulmonary vascular remodeling in wild-type mice but not in Tph1(-/-) mice, which suggests that dexfenfluramine-induced pulmonary arterial hypertension is dependent on serotonin synthesis. Dexfenfluramine was also administered to normoxic SERT(+) mice and SERT(+) mice exposed to chronic hypoxia. Dexfenfluramine and SERT overexpression had additive effects in increasing pulmonary vascular remodeling; however, in hypoxic SERT(+) mice, dexfenfluramine reduced both systolic right ventricular pressure and pulmonary vascular remodeling. Pulmonary arterial fibroblasts from SERT(+) mice, but not wild-type mice, proliferated in response to hypoxia. Dexfenfluramine inhibited hypoxia-induced proliferation of pulmonary arterial fibroblasts derived from SERT(+) mice in a manner dependent on SERT activity. Dexfenfluramine also inhibited the hypoxia-mediated increase in phosphorylation of p38 mitogen-activated protein kinase in SERT(+) pulmonary arterial fibroblasts. CONCLUSIONS: The results suggest that peripheral serotonin is critical for the development of dexfenfluramine-induced pulmonary arterial hypertension and that dexfenfluramine and SERT overexpression have additive effects on pulmonary vascular remodeling. We propose that dexfenfluramine can also inhibit hypoxia-induced pulmonary vascular remodeling via SERT activity and inhibition of hypoxia-induced p38 mitogen-activated protein kinase.