The Role of the Microtubules in Tumor Necrosis Factor-α–Induced Endothelial Cell Permeability (original) (raw)

2003, American Journal of Respiratory Cell and Molecular Biology

Tumor necrosis factor (TNF)-␣, a major proinflammatory cytofilaments, intermediate filaments, and microtubules (3). Tukine, triggers endothelial cell activation and barrier dysfunction mor necrosis factor (TNF)-␣, a proinflammatory cytokine which are implicated in the pathogenesis of pulmonary edema secreted by macrophages and endothelial cells, has been associated with acute lung injury syndromes. The mechanisms implicated in endothelial cell activation, increased endotheof TNF-␣-induced vascular permeability are not completely unlial cell permeability, and pulmonary edema formation (4, 5). derstood. Our initial experiments demonstrated that TNF-␣-However, the exact mechanisms by which TNF-␣ triggers induced decreases in transendothelial electrical resistance across vascular barrier dysfunction are not precisely defined. We human pulmonary artery endothelial cells are independent of and others have noted that TNF-␣ induces endothelial actin myosin light chain phosphorylation catalyzed by either myosin microfilament rearrangement and intercellular gap formalight chain kinase or Rho kinase. We next assessed the involvement of another cytoskeletal component, the tubulin-based micro-tion that parallel the development of transendothelial pertubule network, and found TNF-␣ to induce a decrease in stable meability (5, 6). It is less clear which signaling pathways tubulin content and partial dissolution of peripheral microare orchestrating these morphologic changes of endothelial tubule network as evidenced by anti-acetylated tubulin and cells and their relative direct contribution to the vascular anti-␤-tubulin immunofluorescent staining, respectively. Microbarrier dysfunction. We have previously shown that TNF-␣ tubule-stabilizing agents, paclitaxel and epothilone B, signifiinduces significant actin microfilament rearrangement by cantly attenuated TNF-␣-induced decreases in transendothelial myosin light chain phosphorylation, as a consequence of electrical resistance, inhibited the cytokine-induced increases the coordinated action of the myosin light chain kinase in actin stress fibers, formation of intercellular gap, and restored (MLCK) and Rho kinase (5). However, TNF-␣-induced the TNF-␣-compromised vascular endothelial (VE)-cadherinendothelial cell barrier dysfunction was shown to evolve based cell-cell junctions. Importantly, neither TNF-␣ nor pacliin an MLCK-and Rho kinase-independent fashion (5), taxel treatment was associated with endothelial cell apoptosis. Inhibition of p38 mitogen-activated protein kinase by SB203580 suggesting that MLCK-independent microfilament changes significantly attenuated TNF-␣-induced microtubule destabiliand/or other cytoskeletal structures, such as intermediate zation, actin rearrangement, and endothelial barrier dysfunction. filaments, microtubules, and adherens junctions may be These results strongly suggest the involvement of microtubule involved. Although it was previously shown that TNF-␣ rearrangement in TNF-␣-induced endothelial cell permeability triggers microtubule disassembly (7), the role of the microvia p38 mitogen-activated protein kinase activation.