Inhibition of lipopolysaccharide-stimulated nitric oxide production in RAW 264.7 macrophages by a synthetic carbazole, LCY-2-CHO.
In activated macrophages, large amounts of nitric oxide (NO) are generated by inducible nitric oxide synthase (iNOS). This is an important mechanism in macrophage-induced cytotoxicity and inflammation. In the present study, a synthetic carbazole compound, 9-(2-chlorobenzyl)-9H-carbazole-3-carbaldehyde (LCY-2-CHO), was found to have an inhibitory effect on lipopolysaccharide (LPS)-stimulated NO generation in RAW 264.7 macrophages (IC50 value of 1.3+/-0.4 microM). LCY-2-CHO did not induce cytotoxicity and had a negligible effect on iNOS activity. To explore the mechanism of inhibition of NO generation by LCY-2-CHO, the expression of the iNOS gene was examined. LCY-2-CHO abolished the LPS-induced expression of both iNOS protein and mRNA in a parallel concentration-dependent manner with IC50 values similar to those required for inhibition of NO generation. LCY-2-CHO did not enhance the degradation of iNOS mRNA. In cells transiently transfected with an iNOS promoter-chloramphenicol acetyltransferase (CAT) reporter construct, LCY-2-CHO attenuated the LPS-induced iNOS promoter activity. However, LCY-2-CHO had no effect on the degradation of IkappaB-alpha or IkappaB-beta, DNA binding activity, or transcriptional activity of nuclear factor-kappaB (NF-kappaB). These results indicate that LCY-2-CHO inhibits NO generation via a decrease in the transcription of iNOS mRNA through a signaling pathway that does not involve NF-kappaB activation.
Tsao
Lo-Ti
LT
Department of Education and Research, Taichung Veterans General Hospital, 407, Taichung, Taiwan, ROC.
Lee
Chun-Yann
CY
Huang
Li-Jiau
LJ
Kuo
Sheng-Chu
SC
Wang
Jih-Pyang
JP
D000818:Animals; D004247:DNA / Q000187:drug effects / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004347:Drug Interactions; D020672:I-kappa B Proteins; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000187:drug effects / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D011401:Promoter Regions, Genetic / Q000187:drug effects; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism
D004268:DNA-Binding Proteins; C083487:I kappa B beta protein; D020672:I-kappa B Proteins; D008070:Lipopolysaccharides; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; D012333:RNA, Messenger; D000072000:NF-KappaB Inhibitor alpha; D009569:Nitric Oxide; D004247:DNA; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse