Rho proteins and the p38-MAPK pathway are important mediators for LPS-induced interleukin-8 expression in human endothelial cells.
Bacterial endotoxin (lipopolysaccharide, or LPS) has potent proinflammatory properties by acting on many cell types, including endothelial cells. Secretion of the CXC-chemokine interleukin-8 (IL-8) by LPS-activated endothelial cells contributes substantially to the inflammatory response. Using human umbilical vein endothelial cells (HUVECs), we analyzed the role of small GTP-binding Rho proteins and p38 mitogen-activated protein kinase (MAPK) for LPS-dependent IL-8 expression in endothelial cells. Specific inactivation of RhoA/Cdc42/Rac1 by Clostridium difficile toxin B-10463 (TcdB-10463) reduced LPS-induced tyrosine phosphorylation, nuclear factor (NF)-kappaB-dependent gene expression, IL-8 messenger RNA, and IL-8 protein accumulation but showed no effect on LPS-dependent p38 MAPK activation. Inhibition of p38 MAPK by SB 202190 also blocked LPS-induced NF-kappaB activation and IL-8 synthesis. Furthermore, selective activation of the p38 MAPK pathway by transient expression of a constitutively active form of MAPK kinase (MKK)6, the upstream activator of p38, was as effective as LPS with respect to IL-8 expression in HUVECs. In summary, our data suggest that LPS-induced NF-kappaB activation and IL-8 synthesis in HUVECs are regulated by both a Rho-dependent signaling pathway and the MKK6/p38 kinase cascade.
Hippenstiel
S
S
Charité, Department of Internal Medicine, Humboldt-University, 13353 Berlin, Germany.
Soeth
S
S
Kellas
B
B
Fuhrmann
O
O
Seybold
J
J
Krüll
M
M
Eichel-Streiber
C
C
Goebeler
M
M
Ludwig
S
S
Suttorp
N
N
D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000378:metabolism*; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases; D020741:rho GTP-Binding Proteins / Q000378:metabolism*
D016209:Interleukin-8; D008070:Lipopolysaccharides; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D020741:rho GTP-Binding Proteins