Prostaglandin I2 analogue, iloprost, down regulates mitogen-activated protein kinases of macrophages.
OBJECTIVE
Vascular endothelial cells (EC) play a pivotal role in diffuse organ injury seen in ARDS and MOFS. On exposure to cytokines or endotoxin (LPS) EC are stimulated to express adhesion molecules as well as proinflammatory and procoagulant activity. However, the potential feedback control of EC on macrophages (M-theta) is not clear. We studied the cellular mechanism of iloprost, a PGI2 analogue, in regulation of TNF production by LPS-stimulated M-theta.


METHODS
Rabbit alveolar M-theta and mouse M-theta RAW 264.7 cells were exposed to Escherichia coli LPS in the presence of various concentrations of iloprost. TNF production was measured by L929 bioassays. To further study the cellular mechanism of iloprost on M-theta activation, RAW 264.7 cells were stimulated by LPS (10 micrograms/ml) in the presence of either iloprost or specific mitogen-activated protein kinase (MAPK) inhibitors, either PD98059 or SB202190. P44/P42 and P38 MAPK activation were evaluated by Western blot assays with anti-phospho MAPK antibodies.


RESULTS
LPS induced M-theta TNF production, which was inhibited by iloprost. Iloprost also attenuated the activation of P44/P42 and P38 induced LPS. Inhibition of P44/P42 with PD98059 or P38 with SB202190 significantly reduced TNF production by LPS-stimulated RAW cells.


CONCLUSIONS
The regulatory mechanism of EC on M-theta activation is dependent on PGI2. The effect of PGI2 on M-theta is, at least in part, mediated through inhibiting MAPKs.
Department of Surgery, University of California, Los Angeles 90095-6904, USA.
C J
CJ
Lo
M
M
Fu
F R
FR
Lo
D000818:Animals; D015153:Blotting, Western; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002460:Cell Line; D004789:Enzyme Activation / Q000187:drug effects; D004926:Escherichia coli; D016285:Iloprost / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects* / Q000201:enzymology*; D016676:Macrophages, Alveolar / Q000187:drug effects / Q000201:enzymology; D008297:Male; D051379:Mice; D011817:Rabbits; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D016285:Iloprost