Different mechanisms in inhibition of rat macrophage nitric oxide synthase expression by FK 506 and cyclosporin A.
The modulatory effect of FK 506 and cyclosporin A (CsA) on the expression of inducible nitric oxide synthase (iNOS) in macrophages and mechanisms of their action were analysed. Isolated rat peritoneal macrophages were cultured for 12 or 24 h with or without lipopolysaccharide (LPS) (5 microg/ml) and in the absence or presence of FK 506 or CsA (0.1 and 1 microg/ml). Total RNA from macrophages was isolated and the expression of the gene for iNOS was assessed by using RT-PCR. The concentration of NO2- in culture supernatants was taken as a measure of nitric oxide (NO) production. FK 506 (0.1 and 1 microg/ml) reduced the LPS-induced increase of NO2- levels by 68% and 81%, respectively. CsA (0.1 and 1 microg/ml) decreased levels of nitrites by 39% and 69%, respectively. The results obtained suggest that both immunosuppressive drugs exhibit dose-dependent inhibitory effect on NO production and that FK 506 is more potent agent than CsA, in this respect. FK 506 exhibits its inhibitory effect on a phosphatase at the transcriptional level in macrophages. iNOS expression down-regulation by CsA is occurred post-transcriptionally.
Strestíková
P
P
Institute of Pharmacology, 1st Faculty of Medicine, Charles University, Czech Republic. pstres@lf1.cuni.cz
Otová
B
B
Filipec
M
M
Masek
K
K
Farghali
H
H
D000818:Animals; D002478:Cells, Cultured; D016572:Cyclosporine / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004587:Electrophoresis, Agar Gel; D015971:Gene Expression Regulation, Enzymologic; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000201:enzymology; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016559:Tacrolimus / Q000494:pharmacology*
D007166:Immunosuppressive Agents; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D009569:Nitric Oxide; D016572:Cyclosporine; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D016559:Tacrolimus