Aminothiol WR-1065 protects endothelial cell morphology against alterations induced by lipopolysaccharide.

In septic patients, lipopolysaccharide (LPS) damages the vascular endothelium, which manifests as tissue edema and impaired healing. This pathology occurs when LPS distorts endothelial cell morphology partly by generating free radicals. A radioprotector that scavenges free radicals, the aminothiol WR-1065 ([N-2-mercaptoethyl]-1-3-diaminopropane) was found in a prior study to normalize the morphology of irradiated endothelial cells (Mooteri SN, Podolski JL, Drab EA, et al: Radiat Res 145:217-224, 1996). The aim of this study was to determine whether WR-1065 also normalized endothelial cell morphology following exposure to LPS. For this aim, portions of bovine aortic endothelial cell cultures were denuded and exposed to LPS at 1 ng/mL. After 30 min, the apical membrane expressed increased integrin receptor to fibronectin, alpha5beta1. After 5 h, the morphology of the cells at the leading edge was distorted, and cell-cell contact was lessened. Also, filamentous actin-containing stress fibers were dissipated; however, filamentous actin content per cell was unchanged. Treatment with 2 mM WR-1065 for 2 h prior to LPS exposure attenuated the increased expression of alpha5beta1 and promoted cell-cell contact in the migrating endothelial cells. WR-1065 also promoted the retention of stress fibers and actin cytoskeletal shape in cells treated with LPS. Thus, LPS distorted endothelial cell morphology after increasing apical membrane expression of alpha5beta1 and dissipating stress fibers, effects prevented by WR-1065.

WR-1065 and radioprotection of vascular endothelial cells. II. Morphology.

Although the aminothiol WR-1065 protects normal tissues, its direct effect on the damage and restoration of the vascular endothelium is not clear. In endothelial cells, WR-1065 attenuates both the DNA damage and the G1-phase arrest induced by radiation. After the destruction of nearby endothelial cells, the survivors rearrange their cytoskeleton, migrate and replicate. To determine the effect of radiation on morphology and migration, portions of bovine aortic endothelial cell cultures were denuded with a pipette tip and irradiated (137Cs gamma rays). The following observations were noted after 5 Gy: within 10 min, there was increased formation of protein-mixed disulfides including actin-mixed disulfide; after 30-min, alpha 5 beta 1, the integrin receptor for fibronectin, was up-regulated on the apical membrane surface. Within 5 h, actin-containing stress fibers reorganized, although there was no change in the total filamentous (F-)actin content within the cells. Compared to controls after 24 h, the irradiated cells had migrated 15% farther (P < 0.01), and at the leading edge covered twice the surface area (P < 0.0001). The addition of 2 mM WR-1065 for 2 h before 5 Gy inhibited the increased expression of alpha 5 beta 1, promoted retention of stress fibers and prevented the enhanced cell migration and spreading. These results indicate that WR-1065 prevents radiation-induced morphological responses. This effect appears to be mediated by an impact on both adhesion molecule expression and cytoskeletal reorganization.