Valproic acid reversed pathologic endothelial cell gene expression profile associated with ischemia–reperfusion injury in a swine hemorrhagic shock model

Abstract

Vascular endothelial cells serve as the first line of defense for end organs after ischemia and reperfusion injuries. The full etiology of this dysfunction is poorly understood, and valproic acid (VPA) has proven to be beneficial after traumatic injury. The purpose of this study was to determine the mechanism of action through which VPA exerts its beneficial effects. Sixteen Yorkshire swine underwent a standardized protocol for an ischemia-reperfusion injury through hemorrhage and a supraceliac cross-clamp with ensuing 6-hour resuscitation. The experimental swine (n = 6), received VPA at cross-clamp application and were compared with a sham (n = 5) and injury-control models (n = 5). Aortic endothelium was harvested, and microarray analysis was performed along with a functional clustering analysis with gene transcript validation using relative quantitative polymerase chain reaction. Clinical comparison of experimental swine matched for sex, weight, and length demonstrated that VPA significantly decreased resuscitative requirements, with improved hemodynamics and physiologic laboratory measurements. Six transcript profiles from the VPA treatment were compared with the 1536 gene transcripts (529 up and 1007 down) from sham and injury-control swine. Microarray analysis and a Database for Annotation, Visualization and Integrated Discovery functional pathway analysis approach identified biologic processes associated with pathologic vascular endothelial function, specifically through functional cluster pathways involving apoptosis/cell death and angiogenesis/vascular development, with five specific genes (THBS1, TNFRSF12A, ANGPTL4, RHOB, and RTN4) identified as members of both functional clusters. This study also examined gene expression of transforming growth factor (TGF)-β (TGF-β1, TGF-β2, and TGF-β-releasing thrombospondin 1 [THBS1]) and genes expressing vascular endothelial growth factor (VEGF) C, VEGFD, and VEGFR1 and found that these genes were involved in the endothelial functional preservation associated with VPA administration. VPA minimized pathologic endothelial cell function through the TGF-β and VEGF functional pathways. This study also implicates that integrated functional modeling and analysis will enable advancements in endothelial dysfunction using a systems biology approach.