title: Angiotensin II inhibits interleukin-6 mRNA expression of LPS-stimulated macrophages through down-regulating calcium signaling.
abstract: BACKGROUND
  The renin-angiotensin system plays a key role in the regulation of blood pressure following hemorrhage and shock. Recent studies also suggest renin-angiotensin system regulates inflammatory mediator production although the amechanism is largely unknown. This purpose of the study was to examine the effect of angiotensin II on macrophage (MØ) IL-6 messenger RNA (mRNA) expression induced by lipopolysaccharide (LPS) and on the alterations in the calcium influx.
  
  
  METHODS
  J774A.1 cells, a mouse MØ cell line, were exposed to E. coli LPS (1 or 10 μg/ml) in the presence of angiotensin II (10 nM to 1 μM). IL-6 mRNA expression was determined by the reverse transcription polymerase chain reaction technique. IL-6 protein production was measured by ELISA. To examine the involvement of calcium signaling in IL-6 mRNA expression, MØ were exposed to various calcium agonists and antagonists in the presence of LPS stimulation. Changes of intracellular [Ca(2+)] by LPS stimulation and angiotensin II treatment were determined by a fura-2 fluorescence ratio method.
  
  
  RESULTS
  LPS stimulation increased MØ IL-6 mRNA expression, which was inhibited by Angiotensin II in a dose-dependent fashion. Both thapsigargin and A23187 augmented the IL-6 mRNA levels induced by LPS stimulation, but only thapsigargin was able to induce IL-6 mRNA directly. TMB-8 but not verapamil inhibited LPS-stimulated MØ IL-6 mRNA. Finally, angiotensin II significantly altered the changes in intracellular [Ca(2+)] levels induced by LPS stimulation by reducing both the peak and slope of calcium spikes.
  
  
  CONCLUSIONS
  Our data show that calcium signaling is closely related to IL-6 mRNA expression. Angiotensin II inhibits IL-6 mRNA expression of LPS-stimulated MØ. The inhibitory effects of angiotensin II appear, at least in part, to be mediated through down regulating calcium dependent pathways.
authors.affiliation: Division of Trauma, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan. jehlo@adm.cgmh.org.tw
authors.forename: Chong-Jeh
authors.initials: CJ
authors.lastname: Lo
authors.forename: Emily J
authors.initials: EJ
authors.lastname: Lo
mesh_terms: D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002118:Calcium / Q000819:agonists / Q000378:metabolism*; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay; D005786:Gene Expression Regulation; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000093242:Interleukin-6 Inhibitors
chemical_list: D000804:Angiotensin II; D015415:Biomarkers; D002118:Calcium; D015850:Interleukin-6; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D000093242:Interleukin-6 Inhibitors; C440499:lipopolysaccharide, Escherichia coli O111 B4