Tumor necrosis factor (
TNF)-alpha, a major proinflammatory
cytokine, triggers endothelial cell activation and barrier dysfunction which are implicated in the pathogenesis of
pulmonary edema associated with
acute lung injury syndromes. The mechanisms of
TNF-alpha-induced vascular permeability are not completely understood. Our initial experiments demonstrated that
TNF-alpha-induced decreases in transendothelial electrical resistance across human pulmonary artery endothelial cells are independent of
myosin light chain phosphorylation catalyzed by either
myosin light chain kinase or
Rho kinase. We next assessed the involvement of another cytoskeletal component, the
tubulin-based microtubule network, and found
TNF-alpha to induce a decrease in stable
tubulin content and partial dissolution of peripheral microtubule network as evidenced by anti-acetylated
tubulin and anti-
beta-tubulin immunofluorescent staining, respectively. Microtubule-
stabilizing agents,
paclitaxel and
epothilone B, significantly attenuated
TNF-alpha-induced decreases in transendothelial electrical resistance, inhibited the
cytokine-induced increases in actin stress fibers, formation of intercellular gap, and restored the
TNF-alpha-compromised vascular endothelial (
VE)-cadherin-based cell-cell junctions. Importantly, neither
TNF-alpha nor
paclitaxel treatment was associated with endothelial cell apoptosis. Inhibition of
p38 mitogen-activated protein kinase by
SB203580 significantly attenuated
TNF-alpha-induced microtubule destabilization, actin rearrangement, and endothelial barrier dysfunction. These results strongly suggest the involvement of microtubule rearrangement in
TNF-alpha-induced endothelial cell permeability via
p38 mitogen-activated protein kinase activation.