Z. Wang1, L. Kong1, J. Kang1, D. K. Nakayama2, P. S. Dale1, D. W. Ashley1 1The Medical Center Navicent Health, Mercer University School Of Medicine,Division Of Trauma, Division Of Basic Sciences, Division Of Surgical Oncology, Department Of Surgery,Macon, GA, USA 2West Virginia University School Of Medicine,Department Of Surgery,Morgantown, WV, USA
Introduction: Endothelial hypermeability mediates edema formation, and contributes to morbidity and death in trauma and the systemic inflammatory response syndrome. Inflammatory cytokines including interleukin-1beta (IL-l) are known to activate matrix metalloproteinases (MMPs), a potential mechanism by which cytokines may disrupt endothelial barrier. The mechanism by which proinflammatory cytokines disrupt endothelial permeability is poorly understood. We investigated if IL-1 would induce endothelial hypermeability through activation of p38 mitogen-activated protein kinase (MAPK) and Jun N-terminal kinase (JNK) and induction of MMP-9.
Methods: Vascular endothelial cells (EC) were incubated with and without IL-1, a MMP-9 inhibitor, and inhibitors of p38 MAPK (SB202190) and JNK (SP600125). RT-PCR and Western blotting measured MMP-9 mRNA and protein, respectively. Gelatin zymography quantitated MMP-9 release. Horseradish peroxidase diffusion through MVEC monolayer assessed endothelial permeability. The kinases were assessed with immunoblotting and activity assay.
Results: IL-l activated p38 MAPK and JNK, promoted expression of MMP-9 mRNA and protein and release of MMP-9 activity, and increased endothelial permeability. IL-1-induced endothelial hypermeability was significantly attenuated by pharmacological inhibitors of p38 MAPK, JNK and MMP-9, respectively. Moreover, pharmacological inhibition of p38 MAPK and JNK reduced MMP-9 release in response to IL-1 stimulation.
Conclusion: The proinflammatory IL-1 induces endothelial hypermeability via activation of p38 MAPK and JNK, and subsequent release of MMP-9. Endothelial MMP-9 expression and activity may play a role in the pathogenesis of vascular hyperpermeability in microcirculation in the setting of trauma and cytokine activation syndromes. JNK, p38 MAPK and MMP-9 may be therapeutic targets for endothelial protection from inflammatory injury.