RESUMO
Introduction: The ribosomal protein L3-like (RPL3L) is a heart and skeletal muscle-specific ribosomal protein and paralogue of the more ubiquitously expressed RPL3 protein. Mutations in the human RPL3L gene are linked to childhood cardiomyopathy and age-related atrial fibrillation, yet the function of RPL3L in the mammalian heart remains unknown. Methods and Results: Here, we observed that mouse cardiac ventricles express RPL3 at birth, where it is gradually replaced by RPL3L in adulthood but re-expressed with induction of hypertrophy in adults. Rpl3l gene-deleted mice were generated to examine the role of this gene in the heart, although Rpl3l -/- mice showed no overt changes in cardiac structure or function at baseline or after pressure overload hypertrophy, likely because RPL3 expression was upregulated and maintained in adulthood. mRNA expression analysis and ribosome profiling failed to show differences between the hearts of Rpl3l null and wild type mice in adulthood. Moreover, ribosomes lacking RPL3L showed no differences in localization within cardiomyocytes compared to wild type controls, nor was there an alteration in cardiac tissue ultrastructure or mitochondrial function in adult Rpl3l -/- mice. Similarly, overexpression of either RPL3 or RPL3L with adeno-associated virus -9 in the hearts of mice did not cause discernable pathology. However, by 18 months of age Rpl3l -/- null mice had significantly smaller hearts compared to wild type littermates. Conclusion: Thus, deletion of Rpl3l forces maintenance of RPL3 expression within the heart that appears to fully compensate for the loss of RPL3L, although older Rpl3l -/- mice showed a mild but significant reduction in heart weight.
RESUMO
Duchenne muscular dystrophy (DMD) is an X-linked recessive disease caused by mutations in the gene encoding dystrophin. Loss of dystrophin protein compromises the stability of the sarcolemma membrane surrounding each muscle cell fiber, leading to membrane ruptures and leakiness that induces myofiber necrosis, a subsequent inflammatory response, and progressive tissue fibrosis with loss of functional capacity. Cathepsin S (Ctss) is a cysteine protease that is actively secreted in areas of tissue injury and ongoing inflammation, where it participates in extracellular matrix remodeling and healing. Here we show significant induction of Ctss expression and proteolytic activity following acute muscle injury or in muscle from mdx mice, a model of DMD. To examine the functional ramifications associated with greater Ctss expression, the Ctss gene was deleted in the mdx genetic background, resulting in protection from muscular dystrophy pathogenesis that included reduced myofiber turnover and histopathology, reduced fibrosis, and improved running capacity. Mechanistically, deletion of the Ctss gene in the mdx background significantly increased myofiber sarcolemmal membrane stability with greater expression and membrane localization of utrophin, integrins, and ß-dystroglycan, which anchor the membrane to the basal lamina and underlying cytoskeletal proteins. Consistent with these results, skeletal muscle-specific transgenic mice overexpressing Ctss showed increased myofiber necrosis, muscle histopathology, and a functional deficit reminiscent of muscular dystrophy. Hence, Ctss induction during muscular dystrophy is a pathologic event that partially underlies disease pathogenesis, and its inhibition might serve as a new therapeutic strategy in DMD.
Assuntos
Catepsinas/biossíntese , Regulação da Expressão Gênica no Desenvolvimento , Fibras Musculares Esqueléticas/enzimologia , Distrofia Muscular Animal/enzimologia , Distrofia Muscular de Duchenne/enzimologia , Animais , Citoesqueleto/enzimologia , Citoesqueleto/genética , Citoesqueleto/patologia , Camundongos , Camundongos Endogâmicos mdx , Camundongos Knockout , Fibras Musculares Esqueléticas/patologia , Distrofia Muscular Animal/genética , Distrofia Muscular Animal/patologia , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/patologia , Necrose , Proteólise , Sarcolema/enzimologia , Sarcolema/genética , Sarcolema/patologiaRESUMO
OBJECTIVE: Periostin is a secreted protein that can alter extracellular matrix remodeling in response to tissue injury. However, the functional role of periostin in the development of atherosclerotic plaques has yet to be described despite its observed induction in diseased vessels and presence in the serum. APPROACH AND RESULTS: Hyperlipidemic, apolipoprotein E-null mice (ApoE(-/) (-)) were crossed with periostin (Postn(-/-)) gene-deleted mice and placed on a high-fat diet for 6 or 14 weeks to induce atherosclerosis. En face analysis of aortas showed significantly decreased lesion areas of ApoE(-/-) Postn(-/-) mice compared with ApoE(-/-) mice, as well as a reduced inflammatory response with less macrophage content. Moreover, diseased aortas from ApoE(-/-) Postn(-/-) mice displayed a disorganized extracellular matrix with less collagen cross linking and smaller fibrotic caps, as well as increased matrix metalloproteinase-2, metalloproteinase-13, and procollagen-lysine, 2-oxoglutarate 5-dioxygenase-1 mRNA expression. Furthermore, the loss of periostin was associated with a switch in vascular smooth muscle cells toward a more proliferative and synthetic phenotype. Mechanistically, the loss of periostin reduced macrophage recruitment by transforming growth factor-ß in cellular migration assays. CONCLUSIONS: These are the first genetic data detailing the function of periostin as a regulator of atherosclerotic lesion formation and progression. The data suggest that periostin could be a therapeutic target for atherosclerotic plaque formation through modulation of the immune response and extracellular matrix remodeling.
Assuntos
Aorta Torácica/metabolismo , Doenças da Aorta/prevenção & controle , Aterosclerose/prevenção & controle , Moléculas de Adesão Celular/deficiência , Matriz Extracelular/metabolismo , Deleção de Genes , Inflamação/prevenção & controle , Remodelação Vascular , Animais , Aorta Torácica/imunologia , Aorta Torácica/patologia , Doenças da Aorta/genética , Doenças da Aorta/imunologia , Doenças da Aorta/metabolismo , Doenças da Aorta/patologia , Apolipoproteínas E/deficiência , Apolipoproteínas E/genética , Aterosclerose/genética , Aterosclerose/imunologia , Aterosclerose/metabolismo , Aterosclerose/patologia , Moléculas de Adesão Celular/genética , Movimento Celular , Proliferação de Células , Células Cultivadas , Colágeno/metabolismo , Dieta Hiperlipídica , Modelos Animais de Doenças , Progressão da Doença , Regulação da Expressão Gênica , Inflamação/genética , Inflamação/imunologia , Inflamação/metabolismo , Inflamação/patologia , Macrófagos/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Músculo Liso Vascular/metabolismo , Músculo Liso Vascular/patologia , Miócitos de Músculo Liso/metabolismo , Miócitos de Músculo Liso/patologia , Fenótipo , Placa Aterosclerótica , RNA Mensageiro/metabolismo , Transdução de Sinais , Fatores de TempoRESUMO
RATIONALE: To maintain cardiac mechanical and structural integrity after an ischemic insult, profound alterations occur within the extracellular matrix. Osteoglycin is a small leucine-rich proteoglycan previously described as a marker of cardiac hypertrophy. OBJECTIVE: To establish whether osteoglycin may play a role in cardiac integrity and function after myocardial infarction (MI). METHODS AND RESULTS: Osteoglycin expression is associated with collagen deposition and scar formation in mouse and human MI. Absence of osteoglycin in mice resulted in significantly increased rupture-related mortality with tissue disruption, intramyocardial bleeding, and increased cardiac dysfunction, despite equal infarct sizes. Surviving osteoglycin null mice had greater infarct expansion in comparison with wild-type mice because of impaired collagen fibrillogenesis and maturation in the infarcts as revealed by electron microscopy and collagen polarization. Absence of osteoglycin did not affect cardiomyocyte hypertrophy in the remodeling remote myocardium. In cultured fibroblasts, osteoglycin knockdown or supplementation did not alter transforming growth factor-ß signaling. Adenoviral overexpression of osteoglycin in wild-type mice significantly improved collagen quality, thereby blunting cardiac dilatation and dysfunction after MI. In osteoglycin null mice, adenoviral overexpression of osteoglycin was unable to prevent rupture-related mortality because of insufficiently restoring osteoglycin protein levels in the heart. Finally, circulating osteoglycin levels in patients with heart failure were significantly increased in the patients with a previous history of MI compared with those with nonischemic heart failure and correlated with survival, left ventricular volumes, and other markers of fibrosis. CONCLUSIONS: Increased osteoglycin expression in the infarct scar promotes proper collagen maturation and protects against cardiac disruption and adverse remodeling after MI. In human heart failure, osteoglycin is a promising biomarker for ischemic heart failure.
Assuntos
Cardiomegalia/metabolismo , Colágeno/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Infarto do Miocárdio/metabolismo , Animais , Cardiomegalia/patologia , Cicatriz/metabolismo , Fibroblastos/citologia , Fibroblastos/metabolismo , Fibroblastos/fisiologia , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/sangue , Peptídeos e Proteínas de Sinalização Intercelular/genética , Linfotoxina-alfa/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Infarto do Miocárdio/patologia , Miócitos Cardíacos/citologia , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/fisiologia , Ratos , Ratos Endogâmicos Lew , Remodelação VentricularRESUMO
OBJECTIVES: This study sought to investigate the effect of endothelial dysfunction on the development of cardiac hypertrophy and fibrosis. BACKGROUND: Endothelial dysfunction accompanies cardiac hypertrophy and fibrosis, but its contribution to these conditions is unclear. Increased nicotinamide adenine dinucleotide phosphate oxidase-2 (NOX2) activation causes endothelial dysfunction. METHODS: Transgenic mice with endothelial-specific NOX2 overexpression (TG mice) and wild-type littermates received long-term angiotensin II (AngII) infusion (1.1 mg/kg/day, 2 weeks) to induce hypertrophy and fibrosis. RESULTS: TG mice had systolic hypertension and hypertrophy similar to those seen in wild-type mice but developed greater cardiac fibrosis and evidence of isolated left ventricular diastolic dysfunction (p < 0.05). TG myocardium had more inflammatory cells and VCAM-1-positive vessels than did wild-type myocardium after AngII treatment (both p < 0.05). TG microvascular endothelial cells (ECs) treated with AngII recruited 2-fold more leukocytes than did wild-type ECs in an in vitro adhesion assay (p < 0.05). However, inflammatory cell NOX2 per se was not essential for the profibrotic effects of AngII. TG showed a higher level of endothelial-mesenchymal transition (EMT) than did wild-type mice after AngII infusion. In cultured ECs treated with AngII, NOX2 enhanced EMT as assessed by the relative expression of fibroblast versus endothelial-specific markers. CONCLUSIONS: AngII-induced endothelial NOX2 activation has profound profibrotic effects in the heart in vivo that lead to a diastolic dysfunction phenotype. Endothelial NOX2 enhances EMT and has proinflammatory effects. This may be an important mechanism underlying cardiac fibrosis and diastolic dysfunction during increased renin-angiotensin activation.
Assuntos
Cardiomegalia/enzimologia , Endotélio Vascular/enzimologia , Mediadores da Inflamação/fisiologia , Glicoproteínas de Membrana/fisiologia , Células-Tronco Mesenquimais/enzimologia , NADPH Oxidases/fisiologia , Disfunção Ventricular Esquerda/enzimologia , Animais , Cardiomegalia/genética , Cardiomegalia/patologia , Células Cultivadas , Endotélio Vascular/patologia , Fibrose/enzimologia , Fibrose/genética , Fibrose/patologia , Insuficiência Cardíaca Diastólica/enzimologia , Insuficiência Cardíaca Diastólica/genética , Insuficiência Cardíaca Diastólica/patologia , Humanos , Masculino , Glicoproteínas de Membrana/genética , Células-Tronco Mesenquimais/patologia , Camundongos , Camundongos Transgênicos , NADPH Oxidase 2 , NADPH Oxidases/genética , Disfunção Ventricular Esquerda/genética , Disfunção Ventricular Esquerda/patologiaRESUMO
AIMS: The cardiac extracellular matrix is highly involved in regulating inflammation, remodelling, and function of the heart. Whether matrix alterations relate to the degree of inflammation, fibrosis, and overall rejection in the human transplanted heart remained, until now, unknown. METHODS AND RESULTS: Expression of matricellular proteins, proteoglycans, and metalloproteinases (MMPs) and their inhibitors (TIMPs) were investigated in serial endomyocardial biopsies (n = 102), in a cohort of 39 patients within the first year after cardiac transplantation. Out of 15 matrix-related proteins, intragraft transcript and protein levels of syndecan-1 and MMP-9 showed a strong association with the degree of cardiac allograft rejection (CAR), the expression of pro-inflammatory cytokines tumour necrosis factor (TNF)-α, interleukin (IL)-6 and transforming growth factor (TGF)-ß, and with infiltrating CD3⺠T-cells and CD68⺠monocytes. In addition, SPARC, CTGF, TSP-2, MMP-14, TIMP-1, Testican-1, TSP-1, Syndecan-1, MMP-2, -9, and -14, as well as IL-6 and TGF-ß transcript levels and inflammatory infiltrates all strongly relate to collagen expression in the transplanted heart. More importantly, receiver operating characteristic curve analysis demonstrated that syndecan-1 and MMP-9 transcript levels had the highest area under the curve (0.969 and 0.981, respectively), thereby identifying both as a potential decision-making tool to discriminate rejecting from non-rejecting hearts. CONCLUSION: Out of 15 matrix-related proteins, we identified synd-1 and MMP-9 intragraft transcript levels of as strong predictors of human CAR. In addition, a multitude of non-structural matrix-related proteins closely associate with collagen expression in the transplanted heart. Therefore, we are convinced that these findings deserve further investigation and are likely to be of clinical value to prevent human CAR.
Assuntos
Matriz Extracelular/metabolismo , Rejeição de Enxerto/patologia , Transplante de Coração , Metaloproteinases da Matriz/metabolismo , Miocárdio/patologia , Aloenxertos , Biomarcadores/metabolismo , Citocinas/metabolismo , Feminino , Fibrose/metabolismo , Fibrose/patologia , Rejeição de Enxerto/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Monócitos/patologia , Miocardite/metabolismo , Miocardite/patologia , Proteoglicanas/metabolismo , Linfócitos T/patologia , Inibidores Teciduais de Metaloproteinases/metabolismoRESUMO
AIMS: Thrombospondin-2 (TSP-2) modulates matrix integrity and myocyte survival in the hypertensive or ageing heart. Whether TSP-2 may affect cardiac inflammation and injury, in particular during acute viral myocarditis, is completely unknown. METHODS AND RESULTS: Therefore, mortality, cardiac inflammation, and function were assessed in TSP-2-null (KO) and wild-type (WT) mice in human Coxsackie virus B3 (CVB3)-induced myocarditis. TSP-2 KO had an increased mortality when compared with WT mice during viral myocarditis. The absence of TSP-2 resulted in increased cardiac inflammation and injury at 14 days, which resulted in depressed systolic function [fractional shortening (FS); 34 ± 2.6 in WT vs. 24 ± 1.8 in KO mice, P< 0.05] and increased cardiac dilatation (end-diastolic dimensions, mm; 3.7 ± 0.09 in WT vs. 4.8 ± 0.06 in KO mice, P< 0.05) 35 days post-infection. Lack of TSP-2 resulted in a decreased activation of the anti-inflammatory T-regulatory cells, as indicated by a lower number of CD25-positive T-cells, and significantly decreased gene expression of regulatory T-cell markers, Foxp3 and CTLA-4. Finally, overexpression of TSP-2 in WT hearts using cardiotropic vectors derived from adeno-associated virus serotype 9 (AAV9) inhibited cardiac inflammation and injury at 14 days and improved cardiac function at 35 days post-CVB3 infection when compared with control AAV9. CONCLUSION: TSP-2 has a protective role against cardiac inflammation, injury, and dysfunction in acute viral myocarditis.
Assuntos
Enterovirus Humano B/patogenicidade , Terapia Genética , Ativação Linfocitária , Miocardite/prevenção & controle , Miocárdio/metabolismo , Linfócitos T Reguladores/metabolismo , Trombospondinas/metabolismo , Disfunção Ventricular Esquerda/prevenção & controle , Animais , Antígeno CTLA-4/metabolismo , Dependovirus/genética , Modelos Animais de Doenças , Fibrose , Fatores de Transcrição Forkhead/metabolismo , Regulação da Expressão Gênica , Técnicas de Transferência de Genes , Vetores Genéticos , Humanos , Masculino , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C3H , Camundongos Knockout , Contração Miocárdica , Miocardite/diagnóstico por imagem , Miocardite/genética , Miocardite/imunologia , Miocardite/metabolismo , Miocardite/fisiopatologia , Miocárdio/imunologia , Miocárdio/patologia , Necrose , RNA Mensageiro/metabolismo , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/virologia , Trombospondinas/deficiência , Trombospondinas/genética , Fatores de Tempo , Ultrassonografia , Disfunção Ventricular Esquerda/diagnóstico por imagem , Disfunção Ventricular Esquerda/genética , Disfunção Ventricular Esquerda/imunologia , Disfunção Ventricular Esquerda/metabolismo , Disfunção Ventricular Esquerda/fisiopatologia , Função Ventricular EsquerdaRESUMO
BACKGROUND: CCN1 is an evolutionary ancient matricellular protein that modulates biological processes associated with tissue repair. Induction at sites of injury was observed in conditions ranging from skin wounds to cardiac diseases, including ischemic and inflammatory cardiomyopathy. Here, we provide evidence of a novel function of CCN1 as a modulator of immune cell migration. METHODS AND RESULTS: to understand the role of CCN1 in cardiomyopathies and to evaluate its therapeutic potential, we overexpressed CCN1 using an adenoviral hepatotropic vector in murine experimental autoimmune myocarditis, a model of human inflammatory cardiomyopathy. CCN1 gene transfer significantly reduced cardiac disease score and immune cell infiltration. In vivo tracking of hemagglutinin epitope-tagged CCN1 revealed binding to spleen macrophages but not to cardiomyocytes. Unexpectedly, CCN1 therapy left cardiac chemokine and cytokine expression unchanged but instead strongly inhibited the migration of spleen macrophages and lymphocytes, as evidenced by ex vivo transwell assays. In accordance with the ex vivo data, in vitro preincubation with CCN1 diminished transwell migration of human monocytes and abrogated their chemotactic response to monocyte chemoattractant protein-1, macrophage inflammatory protein-1α, and stromal cell-derived factor-1α. Further mechanistic studies showed that CCN1-driven modulation of immune cell migration is mimicked in part by cyclic RGD peptides currently in clinical evaluation for cancer therapy. CONCLUSIONS: our proof-of-concept study suggests investigation of CCN1 as a novel, endogenous "parent compound" for chemotaxis modulation and of cyclic RGD peptides as a class of partially CCN1-mimetic drugs with immediate potential for clinical evaluation in cardiac diseases associated with chronic pathogenic inflammation.
Assuntos
Doenças Autoimunes/metabolismo , Doenças Autoimunes/prevenção & controle , Movimento Celular/fisiologia , Proteína Rica em Cisteína 61/metabolismo , Miocardite/metabolismo , Miocardite/prevenção & controle , Adulto , Animais , Doenças Autoimunes/patologia , Biomimética , Movimento Celular/efeitos dos fármacos , Células Cultivadas , Proteína Rica em Cisteína 61/genética , Proteína Rica em Cisteína 61/farmacologia , Modelos Animais de Doenças , Feminino , Técnicas de Transferência de Genes , Humanos , Leucócitos Mononucleares/citologia , Leucócitos Mononucleares/efeitos dos fármacos , Fígado/citologia , Fígado/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Pessoa de Meia-Idade , Monócitos/citologia , Monócitos/efeitos dos fármacos , Miocardite/patologia , Peptídeos Cíclicos/farmacologia , Proteínas Recombinantes/farmacologia , Baço/citologia , Baço/efeitos dos fármacosRESUMO
The transforming and tumor growth-promoting properties of Axl, a member of the Tyro3, Axl, and Mer (TAM) family of receptor tyrosine kinases (TAMRs), are well recognized. In contrast, little is known about the role of the TAMR ligand growth arrest-specific gene 6 (Gas6) in tumor biology. By using Gas6-deficient (Gas6(-/-)) mice, we show that bone marrow-derived Gas6 promotes growth and metastasis in different experimental cancer models, including one resistant to vascular endothelial growth factor inhibitors. Mechanistic studies reveal that circulating leukocytes produce minimal Gas6. However, once infiltrated in the tumor, leukocytes up-regulate Gas6, which is mitogenic for tumor cells. Consistent herewith, impaired tumor growth in Gas6(-/-) mice is rescued by transplantation of wild-type bone marrow and, conversely, mimicked by transplantation of Gas6(-/-) bone marrow into wild-type hosts. These findings highlight a novel role for Gas6 in a positive amplification loop, whereby tumors promote their growth by educating infiltrating leukocytes to up-regulate the production of the mitogen Gas6. Hence, inhibition of Gas6 might offer novel opportunities for the treatment of cancer.
Assuntos
Movimento Celular , Peptídeos e Proteínas de Sinalização Intercelular/biossíntese , Leucócitos/metabolismo , Leucócitos/patologia , Mitógenos/biossíntese , Neoplasias/patologia , Animais , Transplante de Medula Óssea , Proliferação de Células , Regulação Neoplásica da Expressão Gênica , Inflamação/complicações , Inflamação/patologia , Peptídeos e Proteínas de Sinalização Intercelular/deficiência , Peptídeos e Proteínas de Sinalização Intercelular/genética , Interleucina-10/metabolismo , Fator Estimulador de Colônias de Macrófagos/metabolismo , Macrófagos/metabolismo , Macrófagos/patologia , Camundongos , Metástase Neoplásica , Neoplasias/irrigação sanguínea , Neoplasias/enzimologia , Neoplasias/genética , Neovascularização Patológica/complicações , Neovascularização Patológica/genética , Receptores Proteína Tirosina Quinases/genética , Receptores Proteína Tirosina Quinases/metabolismo , Células Estromais/metabolismo , Células Estromais/patologia , Regulação para Cima/genéticaRESUMO
BACKGROUND: The progressive shift from a young to an aged heart is characterized by alterations in the cardiac matrix. The present study investigated whether the matricellular protein thrombospondin-2 (TSP-2) may affect cardiac dimensions and function with physiological aging of the heart. METHODS AND RESULTS: TSP-2 knockout (KO) and wild-type mice were followed up to an age of 60 weeks. Survival rate, cardiac function, and morphology did not differ at a young age in TSP-2 KO compared with wild-type mice. However, >55% of the TSP-2 KO mice died between 24 and 60 weeks of age, whereas <10% of the wild-type mice died. In the absence of TSP-2, older mice displayed a severe dilated cardiomyopathy with impaired systolic function, increased cardiac dilatation, and fibrosis. Ultrastructural analysis revealed progressive myocyte stress and death, accompanied by an inflammatory response and replacement fibrosis, in aging TSP-2 KO animals, whereas capillary or coronary morphology or density was not affected. Importantly, adeno-associated virus-9 gene-mediated transfer of TSP-2 in 7-week-old TSP-2 KO mice normalized their survival and prevented dilated cardiomyopathy. In TSP-2 KO animals, age-related cardiomyopathy was accompanied by increased matrix metalloproteinase-2 and decreased tissue transglutaminase-2 activity, together with impaired collagen cross-linking. At the cardiomyocyte level, TSP-2 deficiency in vivo and its knockdown in vitro decreased the activation of the Akt survival pathway in cardiomyocytes. CONCLUSIONS: TSP-2 expression in the heart protects against age-dependent dilated cardiomyopathy.
Assuntos
Envelhecimento , Cardiomiopatia Dilatada/etiologia , Miocárdio/metabolismo , Trombospondinas/deficiência , Animais , Cardiomiopatia Dilatada/mortalidade , Cardiomiopatia Dilatada/patologia , Cardiomiopatia Dilatada/prevenção & controle , Morte Celular , Ativação Enzimática , Feminino , Fibrose , Técnicas de Transferência de Genes , Masculino , Metaloproteinase 2 da Matriz/metabolismo , Camundongos , Camundongos Knockout , Miocardite/etiologia , Miocárdio/patologia , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/ultraestrutura , Proteínas Proto-Oncogênicas c-akt/metabolismo , Trombospondinas/genética , Regulação para CimaRESUMO
The matricellular protein SPARC (secreted protein, acidic and rich in cysteine, also known as osteonectin) mediates cell-matrix interactions during wound healing and regulates the production and/or assembly of the extracellular matrix (ECM). This study investigated whether SPARC functions in infarct healing and ECM maturation after myocardial infarction (MI). In comparison with wild-type (WT) mice, animals with a targeted inactivation of SPARC exhibited a fourfold increase in mortality that resulted from an increased incidence of cardiac rupture and failure after MI. SPARC-null infarcts had a disorganized granulation tissue and immature collagenous ECM. In contrast, adenoviral overexpression of SPARC in WT mice improved the collagen maturation and prevented cardiac dilatation and dysfunction after MI. In cardiac fibroblasts in vitro, reduction of SPARC by short hairpin RNA attenuated transforming growth factor beta (TGF)-mediated increase of Smad2 phosphorylation, whereas addition of recombinant SPARC increased Smad2 phosphorylation concordant with increased Smad2 phosphorylation in SPARC-treated mice. Importantly, infusion of TGF-beta rescued cardiac rupture in SPARC-null mice but did not significantly alter infarct healing in WT mice. These findings indicate that local production of SPARC is essential for maintenance of the integrity of cardiac ECM after MI. The protective effects of SPARC emphasize the potential therapeutic applications of this protein to prevent cardiac dilatation and dysfunction after MI.
Assuntos
Ruptura Cardíaca Pós-Infarto/metabolismo , Infarto do Miocárdio/metabolismo , Osteonectina/deficiência , Animais , Proteínas de Ligação ao Cálcio/genética , Proteínas da Matriz Extracelular/genética , Feminino , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Tecido de Granulação/efeitos dos fármacos , Tecido de Granulação/metabolismo , Tecido de Granulação/patologia , Coração/fisiopatologia , Ruptura Cardíaca Pós-Infarto/fisiopatologia , Ruptura Cardíaca Pós-Infarto/prevenção & controle , Hemodinâmica/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Infarto do Miocárdio/patologia , Infarto do Miocárdio/fisiopatologia , Miocárdio/metabolismo , Miocárdio/patologia , Osteonectina/genética , Osteonectina/fisiologia , Ratos , Ratos Endogâmicos Lew , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais/efeitos dos fármacos , Proteína Smad2/genética , Análise de Sobrevida , Fator de Crescimento Transformador beta/farmacologia , Fator de Crescimento Transformador beta/fisiologia , Fator de Crescimento Transformador beta/uso terapêuticoRESUMO
BACKGROUND: The cell-associated proteoglycan syndecan-1 (Synd1) closely regulates inflammation and cell-matrix interactions during wound healing and tumorigenesis. The present study investigated whether Synd1 may also regulate cardiac inflammation, matrix remodeling, and function after myocardial infarction (MI). METHODS AND RESULTS: First, we showed increased protein and mRNA expression of Synd1 from 24 hours on, reaching its maximum at 7 days after MI and declining thereafter. Targeted deletion of Synd1 resulted in increased inflammation and accelerated, yet functionally adverse, infarct healing after MI. In concordance, adenoviral gene expression of Synd1 protected against exaggerated inflammation after MI, mainly by reducing transendothelial adhesion and migration of leukocytes, as shown in vitro. Increased inflammation in the absence of Synd1 resulted in increased monocyte chemoattractant protein-1 expression, increased activity of matrix metalloproteinase-2 and -9, and decreased activity of tissue transglutaminase, associated with increased collagen fragmentation and disorganization. Exaggerated inflammation and adverse matrix remodeling in the absence of Synd1 increased cardiac dilatation and impaired systolic function, whereas gene overexpression of Synd1 reduced inflammation and protected against cardiac dilatation and failure. CONCLUSIONS: Increased expression of Synd1 in the infarct protects against exaggerated inflammation and adverse infarct healing, thereby reducing cardiac dilatation and dysfunction after MI in mice.
Assuntos
Cardiomiopatia Dilatada/genética , Infarto do Miocárdio/genética , Sindecana-1/genética , Sindecana-1/fisiologia , Remodelação Ventricular/genética , Animais , Cardiomiopatia Dilatada/imunologia , Cardiomiopatia Dilatada/fisiopatologia , Colágeno/genética , Citocinas/genética , Citocinas/imunologia , Modelos Animais de Doenças , Feminino , Expressão Gênica , Coração/fisiologia , Leucócitos/imunologia , Masculino , Metaloproteinase 2 da Matriz/metabolismo , Metaloproteinase 9 da Matriz/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Knockout , Mutagênese , Infarto do Miocárdio/imunologia , Infarto do Miocárdio/fisiopatologia , Miocárdio/enzimologia , Miocárdio/patologia , RNA Mensageiro/metabolismo , Sístole/genética , Remodelação Ventricular/imunologiaRESUMO
BACKGROUND: Acute viral myocarditis is an important cause of cardiac failure in young adults for which there is no effective treatment apart from general heart failure therapy. The present study tested the hypothesis that increased expression of the proteinases urokinase-type plasminogen activator (uPA) and matrix metalloproteinases (MMPs) is implicated in cardiac inflammation, injury, and subsequent failure during Coxsackievirus-B3 (CVB3)-induced myocarditis. METHODS AND RESULTS: First, we showed increased expression and activity of uPA and MMP-9 in wild-type mice at 7 days of CVB3-induced myocarditis. Targeted deletion of uPA, which resulted in reduced MMP activity and cytokine expression or inhibition of MMPs by adenoviral gene overexpression of tissue inhibitor of metalloproteinases-1, decreased cardiac inflammation and reduced myocardial necrosis at 7 days and decreased cardiac fibrosis at 35 days after CVB3 infection. Importantly, loss of uPA or MMP activity prevented CVB3-induced cardiac dilatation and dysfunction, as determined by serial echocardiography. CONCLUSIONS: Loss of uPA or MMP activity reduces the cardiac inflammatory response after CVB3 infection, thereby protecting against cardiac injury, dilatation, and failure during CVB3-induced myocarditis.