Establishment of a method for evaluating endothelial cell injury by TNF-α in vitro for clarifying the pathophysiology of virus-associated acute encephalopathy

BACKGROUND: Virus-associated acute encephalopathy (VAE) is a severe central nervous system complication caused by common viral infections in children. The pathophysiology of VAE is thought to be endothelial injury. This study was designed to establish an in vitro VAE model for evaluating endothelial injury caused by the proinflammatory cytokine TNF-alpha. METHODS: Transwell-grown human umbilical vein endothelial cells (HUVECs) monolayers were incubated with serially diluted TNF-alpha. Transendothelial electrical resistance (TER) was measured using impedance spectroscopy. Permeability changes of HUVECs after TNF-alpha treatment were determined by fluorescein isothiocyanate (FITC)-conjugated dextran. Moreover, TNF-alpha-induced morphological changes in claudin-5 and apoptosis were observed by immunofluorescent staining. RESULTS: The decrease in TER, time of TER recovery to baseline, and increase in permeability were all dependent on TNF-alpha concentration. Immunofluorescent staining showed that claudin-5 was delocalized after TNF-alpha treatment in a dose-dependent manner. ln addition, some apoptotic cells were observed at high TNF-alpha concentrations. CONCLUSION: TER measurement combined with a permeability assay could be useful for evaluating vascular endothelial cell permeability in an in vitro model. These evaluation methods will contribute to both the development of specific treatments focusing on vascular permeability, and the search for a novel therapeutic strategy in VAE treatment.