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1.
Inflammation ; 40(6): 1862-1874, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28755278

RESUMO

Leukocyte recruitment is a fundamental event in the response of the innate immune system to injury. This process is promoted in part by the opening of endothelial cell adherens junctions that allows leukocyte extravasation through gaps between adjacent endothelial cells. VE-cadherin is a key component of endothelial cell adherens junctions and a negative regulator of leukocyte emigration. Accumulating evidence implicates bone morphogenetic protein (BMP) 4 as a critical regulator in vascular biology, but its role in leukocyte extravasation in vitro and in vivo has not been investigated so far. To assess the impact of BMP4 on leukocyte emigration in vivo, we used the thioglycollate-induced peritonitis model. C57BL/6 mice were intraperitoneally (i.p.) injected with recombinant BMP4 in addition to thioglycollate. Compared to solvent-treated controls, we observed higher accumulation of leukocytes in the peritoneal lavage of BMP4-treated mice indicating that BMP4 promotes leukocyte diapedesis into the inflamed peritoneal cavity. Endothelial cell-specific deletion of BMP4 in mice markedly diminished leukocyte diapedesis following thioglycollate administration suggesting that endothelial BMP4 is required for leukocyte recruitment. Consistent with these in vivo results, transwell migration assays with human umbilical vein endothelial cells (HUVECs) in vitro revealed that recombinant BMP4 enhanced leukocyte transmigration through the endothelial monolayer. Conversely, silencing of endothelial BMP4 by siRNA dampened leukocyte diapedesis in vitro. Mechanistic studies showed that loss of BMP4 improved endothelial junction stability by upregulation of VE-cadherin expression in vitro and in vivo. Vice versa, treatment of HUVECs with recombinant BMP4 decreased expression of VE-cadherin and impaired endothelial junction stability shown by Western blotting and immunocytochemistry. Finally, severe endothelial damage in HUVECs in response to serum of patients collected 24 h after survived cardiac arrest was accompanied by increase in leukocyte migration in transwell assays and activation of the BMP pathway most probably by upregulation of endothelial BMP4 RNA and protein expression. Collectively, the present study provides novel evidence that endothelial BMP4 controls leukocyte recruitment through a VE-cadherin-dependent mechanism and that BMP4-induced inflammation might be involved in the pathogenesis of endothelial cell damage following successful resuscitation after cardiac arrest.


Assuntos
Antígenos CD/fisiologia , Proteína Morfogenética Óssea 4/fisiologia , Caderinas/fisiologia , Inflamação , Leucócitos/metabolismo , Migração Transendotelial e Transepitelial , Quimiotaxia de Leucócito , Endotélio Vascular/metabolismo , Parada Cardíaca/patologia , Células Endoteliais da Veia Umbilical Humana , Humanos , Inflamação/etiologia
2.
Inflammation ; 40(2): 442-453, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27995357

RESUMO

The endothelium serves as a selective barrier and controls the exchange of nutrients, hormones, and leukocytes between blood and tissues. Molecular mechanisms contributing to the pathogenesis of endothelial barrier dysfunction remain incompletely understood. Accumulating evidence implicates bone morphogenetic protein (BMP)-modulator BMPER as a key regulator in endothelial biology. Herein, we analyze the impact of BMPER in the control of endothelial barrier function. To assess the role of BMPER in vascular barrier function in mice, we measured the leakage of Evans blue dye from blood into interstitial lung tissue. BMPER+/- mice exhibited a significantly higher degree of vascular leak compared with wild-type siblings. In accordance with our in vivo observation, siRNA-based BMPER knockdown in human umbilical endothelial cells increased endothelial permeability measured by FITC-dextran passage in transwell assays. Mechanistically, BMPER knockdown reduced the expression of VE-cadherin, a pivotal component of endothelial adherens junctions. Conversely, recombinant human BMPER protein upregulated VE-cadherin protein levels and improved endothelial barrier function in transwell assays. The effects of BMPER knockdown on VE-cadherin expression and endothelial permeability were induced by enhanced BMP activity. Supporting this notion, activation of BMP4-Smad-Id1 signaling reduced VE-cadherin levels and impaired endothelial barrier function in vitro. In vivo, Evans blue dye accumulation was higher in the lungs of BMP4-treated C57BL/6 mice compared to controls indicating that BMP4 increased vascular permeability. High levels of BMPER antagonized BMP4-Smad5-Id1 signaling and prevented BMP4-induced downregulation of VE-cadherin and endothelial leakage, suggesting that BMPER exerts anti-BMP effects and restores endothelial barrier function. Taken together, this data demonstrates that BMPER-modulated BMP pathway activity regulates VE-cadherin expression and vascular barrier function.


Assuntos
Proteínas de Transporte/fisiologia , Endotélio Vascular/fisiologia , Animais , Antígenos CD/metabolismo , Proteína Morfogenética Óssea 4/administração & dosagem , Proteína Morfogenética Óssea 4/metabolismo , Proteínas Morfogenéticas Ósseas/metabolismo , Caderinas/metabolismo , Permeabilidade Capilar/efeitos dos fármacos , Proteínas de Transporte/genética , Humanos , Camundongos , Camundongos Endogâmicos C57BL , RNA Interferente Pequeno/farmacologia , Transdução de Sinais
3.
J Pathol ; 231(1): 105-16, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23716395

RESUMO

Epithelial injury is a central finding in pulmonary disease and is accompanied by disruption of epithelial barrier function, leading to pulmonary oedema and inflammation. Injured epithelial cells lose their properties and gain mesenchymal characteristics, a phenotypic switch that contributes to lung remodelling after injury. Here we studied bone morphogenetic protein (BMP) signalling and, in particular, the role of BMP2 and the BMP modulator BMPER in injured lung epithelium. Increased BMP activity, reflected by up-regulation of the Smad1/5-Id1 axis, is detected after injury of lung epithelium in vitro and in vivo. Two members of the BMP family, BMP2 and BMPER, have opposing effects. BMP2 is up-regulated after epithelial injury and causes epithelial dysfunction and hyperpermeability, mediated by the Smad1/5-Id1-dependent down-regulation of E-cadherin. In contrast, BMPER expression is decreased following injury, which in turn impairs epithelial integrity, characterized by reduction of E-cadherin and epithelial leakage in vitro and in vivo. High levels of BMPER antagonized BMP2-Smad5-Id1 signalling and prevented BMP2-mediated decrease of E-cadherin and hyperpermeability, suggesting that BMPER restores epithelial homeostasis. Supporting this notion, pharmacological inhibition of BMP signalling by LDN193189 prevented reduction of E-cadherin and disruption of epithelial barrier function. Inhibition of excessive BMP activation could be a new approach to restore epithelial integrity and prevent disruption of epithelial barrier function after lung injury.


Assuntos
Proteína Morfogenética Óssea 2/antagonistas & inibidores , Proteínas de Transporte/fisiologia , Células Epiteliais/metabolismo , Lesão Pulmonar/metabolismo , Mucosa Respiratória/fisiologia , Animais , Bleomicina/toxicidade , Barreira Alveolocapilar , Proteína Morfogenética Óssea 2/fisiologia , Caderinas/metabolismo , Linhagem Celular , Permeabilidade da Membrana Celular , Células Epiteliais/patologia , Humanos , Lesão Pulmonar/induzido quimicamente , Lesão Pulmonar/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Pirazóis/farmacologia , Pirimidinas/farmacologia , Transdução de Sinais/efeitos dos fármacos , Proteínas Smad Reguladas por Receptor/metabolismo , Regulação para Cima
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