Mechanisms underlying the enhanced elevation of IL-1beta and TNF-alpha mRNA levels following endotoxin challenge in rat alveolar macrophages cultured with low-Mg2+ medium.
We have previously shown that interleukin (IL)-1beta and tumour necrosis factor (TNF)-alpha mRNA levels in rat alveolar macrophages are increased in by endotoxin (lipopolysaccharide; LPS)- stimulation and further enhanced by culturing with low-Mg2+ medium. We have now investigated the mechanisms of underlying this enhancement by using some specific signal transduction inhibitors. The enhanced elevation of both mRNAs levels was suppressed by pretreatment with TMB-8 (which inhibits calcium release from the endoplasmic reticulum) or dexamethasone (which inhibits nuclear factor [NF]-kappaB and activator protein [AP]-1), but not with verapamil or nifedipine (which inhibits calcium channels). The enhancment of IL-1beta, but not TNF-alpha mRNA levels, was suppressed by pretreatment with W-7 (which inhibits calmodulin), whereas the enhancement of TNF-alpha mRNA levels was suppressed by pretreatment with U73122 (which inhibits phospholipase C). Curcumin (an inhibitor of AP-1), suppressed the increases in both mRNAs induced by low-Mg2+ medium alone, but had no suppressive effect on the levels of either mRNA after LPS-stimulation in low-Mg2+ medium. Pyrrolidine dithiocarbamate (an inhibitor of NF-kappaB) prevented the elevation of TNF-alpha mRNA levels induced by low-Mg2+ medium without LPS-stimulation, but had no suppressive effect on IL-1beta mRNA levels. From these results, we conclude that the enhanced elevation of IL-1beta and TNF-alpha mRNA levels seen in LPS-stimulated alveolar macrophages in low-Mg2+ medium occurs partly via the same, and partly via different, signaling pathways.
Oono
Hiromi
H
Department of Veterinary Pharmacology, Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan.
Nakagawa
Masae
M
Miyamoto
Atsushi
A
Ishiguro
Shigeru
S
Nishio
Akira
A
D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects; D002478:Cells, Cultured; D017931:DNA Primers; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D004731:Endotoxins / Q000494:pharmacology*; D007375:Interleukin-1 / Q000096:biosynthesis*; D008070:Lipopolysaccharides / Q000494:pharmacology; D016676:Macrophages, Alveolar / Q000187:drug effects / Q000378:metabolism*; D008275:Magnesium Deficiency / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014158:Transcription, Genetic / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
D017931:DNA Primers; D018076:DNA, Complementary; D004731:Endotoxins; D007375:Interleukin-1; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; C044101:endotoxin, Escherichia coli