Cytoskeletal Alterations in Lipopolysaccharide-Induced Bovine Vascular Endothelial Cell Injury and Its Prevention by Sodium Arsenite

Abstract

Morphological changes, especially cytoskeletal alterations, in lipopolysaccharide (LPS)-induced vascular endothelial cell injury were studied by using LPS-susceptible bovine aortic endothelial cells (BAEC). BAEC in cultures with LPS showed cell rounding, shrinking, and intercellular gap formation. In those cells, LPS caused the disorganization of actin, tubulin, and vimentin. LPS also induced a reduction in the F-actin pool and an elevation in the G-actin pool. Cytoskeletal disorganization affected transendothelial permeability across the endothelial monolayer. Pretreatment of BAEC with sodium arsenite (SA) prevented alterations in LPS-induced BAEC injury. However, posttreatment with SA had no protective effect on them. SA upregulated the expression of heat shock protein in the presence of LPS. The role of SA in prevention of LPS-induced BAEC injury is discussed.Bacterial lipopolysaccharide (LPS), an outer membrane component of gram-negative bacteria, has been shown to directly induce systemic injury of vascular endothelial cells and cause systemic inflammatory response syndrome or multiorgan failure (3). In an in vitro culture system, LPS was reported to induce the injury of bovine aortic endothelial cells (BAEC) directly in the absence of nonendothelial-cell-derived host mediators (11,13,20,23). The LPS-induced BAEC injury is accompanied by altered cell morphology, intercellular gap formation, and increased transendothelial permeability (12,21,24). It was possible that cytoskeletal alterations in LPS-induced BAEC injury were closely linked to intercellular gap formation and endothelial barrier dysfunction (12). However, there were few reports on detailed alterations of cytoskeleton in morphological changes of LPS-induced BAEC injury (12). Furthermore, knowledge regarding factors preventing the alterations in LPS-induced BAEC injury is very limited (15,16,26).Sodium arsenite (SA) is known to be a standard inducer of the heat shock response in vitro and can lead to heat shock protein (HSP) expression in vascular endothelial cells (4, 5). Several reports suggest that SA prevented LPS-induced endothelial cell injury via enhanced heat shock response (6, 27, 32). Therefore, it was of particular interest to determine if and how SA affected morphological changes in LPS-induced BAEC injury. In the present study, we examined the detailed cytoskeletal alterations in LPS-induced vascular endothelial cell injury by using LPS-susceptible BAEC and, furthermore, observed the effect of SA on them. Here we discuss the role of SA in the prevention of LPS-induced BAEC injury. MATERIALS AND METHODSMaterials. LPS from Escherichia coli O55:B5 was obtained from Sigma Chemical Co., St. Louis, Mo. LPS was dissolved at a concentration of 1 mg/ml in distilled water and diluted in culture medium for experiments. SA (Wako Pure Chemicals, Osaka, Japan) was dissolved at a concentration of 1 mM and diluted to 100 M in culture medium for experiments.Cell culture. BAEC were obtained from the Health Science Resource Bank (Tokyo, Japan) and maint...

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