PURPOSE: Endothelial hyperpermeability represent a major hallmark of acute lung injury (ALI) and adult respiratory distress syndrome (ARDS). B-nicotinamide adenine dinucleotide (B-NAD) is one of the naturally occurring substances found in all living cells which when released into the extracellular fluids under pro-inflammatory conditions from several cell sources including endothelium elicit enhancement of barrier function of human pulmonary artery endothelial cells (HPAEC) via P2Y1/Y11 receptors. To study the protective effects of B-NAD (post-treatment) against various agents of endothelial cell (EC) barrier dysfunction namely Thr (thrombin, protease), LPS (lipopolysaccharide), and PLY (pneumolysin), in vitro. To elicit the signaling pathways responsible for B-NAD induced enhancement of EC barrier function.
METHODS: Enhancement of HAPEC barrier function by B-NAD and its protective effect against disruptive molecules LPS, PLY and Thr was characterized by measurement of transendothelial electrical resistance (TER) after the addition of these molecules, using electrical cell-substrate impedance sensing (ECIS). Controlled study of Gq siRNA transfected HPAEC was performed to identify the involvement of Gq signaling pathway in B-NAD induced enhancement of EC barrier function.
RESULTS: Our results suggest that post treatment of B-NAD is protective and attenuate the HPAEC barrier dysfunction induced by LPS, PLY and Thr. Our data also suggest that siRNA based silencing of Gq protein attenuate the B-NAD-induced EC barrier enhancement and therefore, Gq pathway is also involved in B-NAD mediated signaling.
CONCLUSIONS: B-NAD is thus a very efficient regulator of HPAEC integrity and is protective against various barrier disruptive molecules. It acts through both Gs and Gq protein mediated pathways.
CLINICAL IMPLICATIONS: Unpublished mice studies have demonstrated survival benefit in B-NAD treated subjects in LPS-induced sepsis model. Thus better understanding of mechanisms of EC barrier function can contribute to the development of alternative therapeutic strategies for ALI/ARDS and B-NAD may represent a therapeutic potential in clinical settings.
DISCLOSURE: The following authors have nothing to disclose: Pritam Neupane, Supriya Sridhar, Rudolf Lucas, Alexander Verin, Nagavedi Umapathy
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