The role of the transcription factor, Sox18, in pulmonary endothelial barrier function

Hdl Handle:
http://hdl.handle.net/10675.2/346288
Title:
The role of the transcription factor, Sox18, in pulmonary endothelial barrier function
Authors:
Gross, Christine M
Abstract:
Pulmonary endothelial cells form a continuous monolayer on the luminal surface of the lung vasculature. These cells provide a surface for gas exchange and importantly regulate vascular tone. Despite being constantly exposed to hemodynamic forces and/or vasoactive agents, the endothelium also maintains a selectively permeable monolayer under physiologic conditions. However, little is known about the transcriptional events in the pulmonary endothelium that regulate the paracellular barrier under normal conditions or when the cells are exposed to pathological factors such as increased shear stress from congenital heart abnormalities (shunt), lipopolysaccharide (LPS) from the outer membrane of gram negative bacteria, or increased cyclic stretch from mechanical ventilation. Shear stress has been shown to increase, while LPS and cyclic strain have been shown to decrease, alveolar-capillary barrier function. The transcription factor, Sox18, is known to play a key role in regulating vascular development. Here, in ovine pulmonary arterial endothelial cells (PAEC) subjected to physiologic levels of laminar flow (20 dyn/cm2), we identified an increase in trans-endothelial resistance (TER) that correlated with an increase in Sox18 expression. Further, we found that shear stress up-regulated the cellular tight junction protein, Claudin-5, in a Sox18 dependent manner, and Claudin-5 depletion abolished the Sox18 mediated increase in TER in response to shear stress. Utilizing peripheral lung tissue of 4 week old shunt lambs with increased pulmonary blood flow, we found that both Sox18 and Claudin-5 mRNA and protein levels were elevated. In contrast, in human lung microvascular endothelial cells (HLMVEC) exposed to LPS (1EU/ml) for 4 h, the mRNA and protein levels of Sox18 and Claudin-5 were decreased in an NF-κB (p65) and HDAC dependent manner. Sox18 over-expression prevented the LPS dependent loss of TER. Interestingly, this barrier protective effect of Sox18 was abolished by Claudin-5 silencing. In mice given an intratracheal instillation of LPS (2mg/kg, 24 h), we found that the over-expression of Sox18 in the pulmonary vasculature significantly increased Claudin-5 expression and attenuated the LPS mediated increase in lung vascular leak, inflammatory cell infiltration, and inflammatory cytokines in the bronchoalveolar lavage fluid. Sox18 gene delivery also increased oxygen saturation and improved lung function in LPS exposed mice. Similarly, in mice ventilated with high tidal volumes (HTV; 30 ml/kg, 75 bpm, 0.5 FiO2) for 8 h, Sox18 and Claudin-5 protein levels were reduced. However, Sox18 over-expression significantly increased Claudin-5 expression and improved lung function in HTV exposed mice. Together, our study demonstrates that Sox18 is an important regulator of pulmonary endothelial barrier function.
Affiliation:
Vascular Biology Center
Issue Date:
Dec-2014
URI:
http://hdl.handle.net/10675.2/346288
Additional Links:
http://ezproxy.augusta.edu/login?url=http://search.proquest.com/docview/1651540748?accountid=12365
Type:
Dissertation
Appears in Collections:
Theses and Dissertations

Full metadata record

DC FieldValue Language
dc.contributor.authorGross, Christine Men
dc.date.accessioned2015-03-06T16:22:06Zen
dc.date.available2015-03-06T16:22:06Zen
dc.date.issued2014-12en
dc.identifier.urihttp://hdl.handle.net/10675.2/346288-
dc.description.abstractPulmonary endothelial cells form a continuous monolayer on the luminal surface of the lung vasculature. These cells provide a surface for gas exchange and importantly regulate vascular tone. Despite being constantly exposed to hemodynamic forces and/or vasoactive agents, the endothelium also maintains a selectively permeable monolayer under physiologic conditions. However, little is known about the transcriptional events in the pulmonary endothelium that regulate the paracellular barrier under normal conditions or when the cells are exposed to pathological factors such as increased shear stress from congenital heart abnormalities (shunt), lipopolysaccharide (LPS) from the outer membrane of gram negative bacteria, or increased cyclic stretch from mechanical ventilation. Shear stress has been shown to increase, while LPS and cyclic strain have been shown to decrease, alveolar-capillary barrier function. The transcription factor, Sox18, is known to play a key role in regulating vascular development. Here, in ovine pulmonary arterial endothelial cells (PAEC) subjected to physiologic levels of laminar flow (20 dyn/cm2), we identified an increase in trans-endothelial resistance (TER) that correlated with an increase in Sox18 expression. Further, we found that shear stress up-regulated the cellular tight junction protein, Claudin-5, in a Sox18 dependent manner, and Claudin-5 depletion abolished the Sox18 mediated increase in TER in response to shear stress. Utilizing peripheral lung tissue of 4 week old shunt lambs with increased pulmonary blood flow, we found that both Sox18 and Claudin-5 mRNA and protein levels were elevated. In contrast, in human lung microvascular endothelial cells (HLMVEC) exposed to LPS (1EU/ml) for 4 h, the mRNA and protein levels of Sox18 and Claudin-5 were decreased in an NF-κB (p65) and HDAC dependent manner. Sox18 over-expression prevented the LPS dependent loss of TER. Interestingly, this barrier protective effect of Sox18 was abolished by Claudin-5 silencing. In mice given an intratracheal instillation of LPS (2mg/kg, 24 h), we found that the over-expression of Sox18 in the pulmonary vasculature significantly increased Claudin-5 expression and attenuated the LPS mediated increase in lung vascular leak, inflammatory cell infiltration, and inflammatory cytokines in the bronchoalveolar lavage fluid. Sox18 gene delivery also increased oxygen saturation and improved lung function in LPS exposed mice. Similarly, in mice ventilated with high tidal volumes (HTV; 30 ml/kg, 75 bpm, 0.5 FiO2) for 8 h, Sox18 and Claudin-5 protein levels were reduced. However, Sox18 over-expression significantly increased Claudin-5 expression and improved lung function in HTV exposed mice. Together, our study demonstrates that Sox18 is an important regulator of pulmonary endothelial barrier function.en
dc.relation.urlhttp://ezproxy.augusta.edu/login?url=http://search.proquest.com/docview/1651540748?accountid=12365en
dc.rightsCopyright protected. Unauthorized reproduction or use beyond the exceptions granted by the Fair Use clause of U.S. Copyright law may violate federal law.en
dc.subjectSox18en
dc.subjectClaudin-5en
dc.subjectEndothelial Cellsen
dc.subjectPulmonary endothelial barrieren
dc.subjectShear Stressen
dc.subjectCyclic stretchen
dc.subjectLipopolysaccharideen
dc.subjectAcute Lung Injuryen
dc.subjectAcute Respiratory Distress Syndromeen
dc.subjectVentilator Induced Lung Injuryen
dc.titleThe role of the transcription factor, Sox18, in pulmonary endothelial barrier functionen
dc.typeDissertationen
dc.contributor.departmentVascular Biology Centeren
dc.description.advisorBlack, Stephen M.en
dc.description.committeeFulton, David; Verin, Alexander; Rudic, Dan; Birukov, Konstantinen
dc.description.degreeDoctor of Philosophy (Ph.D.)en
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