Interleukin-6 causes endothelial barrier dysfunction via the protein kinase C pathway

ÌÇÐÄ´«Ã½

Abstract

Elevated levels of interleukin-6 (IL-6) have been identified in a variety of systemic inflammatory states that are associated with endothelial barrier dysfunction, but the specific effect of IL-6 on endothelial permeability and the mechanism of action have not been fully examined. The current study evaluated the effect of IL-6 on endothelial permeability and on the distribution of the tight junctional protein ZO-1 and cytoskeletal actin. We also assessed the role of protein kinase C (PKC) in this process.Confluent monolayers of human umbilical vein endothelial cells (n = 6) were exposed to IL-6 (50-500 ng/ml) in the presence or absence of the PKC inhibitor Gö6976 (0.1 microM). Transendothelial electrical resistance (TEER) was measured at the onset of exposure and at 6-h intervals and compared with that of control cells using ANOVA with a Bonferroni multiple comparison test. Additional monolayers were exposed to IL-6, stained for ZO-1 and F-actin, and evaluated via fluorescence microscopy.Interleukin-6 increased endothelial permeability as measured by TEER in a dose- and time-dependent manner. In the presence of PKC inhibitor, the IL-6-mediated increase in permeability was attenuated (18-h TEER 73% of control with IL-6 exposure vs 95% of control with IL-6 + Gö6976 inhibitor, P < 0.01). Microscopy revealed that permeability changes were accompanied by a redistribution of the tight junctional protein ZO-1 and cytoskeletal actin, increased cell contraction, and disorganization of the intercellular borders. Conclusions. The inflammatory cytokine IL-6 is an important mediator of increased endothelial permeability via alterations in the ultrastructural distribution of tight junctions and morphologic changes in cell shape. PKC is a critical intracellular messenger in these IL-6-mediated changes. A better understanding of this mechanism should allow the determination of rational treatment strategies for endothelial barrier dysfunction which occurs in inflammatory states.

View details for

View details for

View details for