title: Cross-regulation of iNOS and COX-2 by its products in murine macrophages under stress conditions.
abstract: Exposure of macrophages to heat shock induces rapid synthesis of heat shock proteins (HSPs) which are important for cell homeostasis. Prostaglandins (PGs) and nitric oxide (NO) are important cell regulatory molecules. We have therefore investigated the interactions between these molecules in the LPS-induced expression of iNOS and COX-2 and in the mitochondrial activity of macrophages. Cultures of the murine macrophage cell line, J774, were exposed to heat shock (43 degrees C, 30 min) and stimulated with LPS (1 microg/ml), concomitantly or after 8h of cell recovery. NO production was measured by Griess reaction; PGE(2) by ELISA; HSP70, iNOS and COX-2 by immunobloting; mitochondrial activity by MTT assay. Heat shock induced HSP70, but not iNOS or COX-2 whereas LPS induced iNOS and COX-2 but not HSP70. When heat shock and LPS were given concomitantly, iNOS but not COX-2 expression was reduced. When a period of 8h was given between heat shock and LPS stimulation, iNOS, COX-2, PGE(2) and NO levels were significantly increased. Under these conditions, the expression of COX-2 was reduced by L-NAME (NO-synthesis inhibitor) and of iNOS by nimesulide (PGs-synthesis inhibitor). Such cross-regulation was not observed in cells at 37 degrees C. These treatments significantly reduced MTT levels in cells at 37 degrees C but not in cells submitted to heat shock. These results suggest that HSPs and cross-regulation of iNOS and COX-2 by their products might be of relevance in the control of cell homeostasis during stress conditions.
authors.affiliation: Department of Immunology, University of Oeste Paulista, Presidente Prudente, Sao Paulo, Brazil.
authors.forename: Luiz Euribel
authors.initials: LE
authors.lastname: Prestes-Carneiro
authors.forename: Marina Tiemi
authors.initials: MT
authors.lastname: Shio
authors.forename: Patrícia Dias
authors.initials: PD
authors.lastname: Fernandes
authors.forename: Sonia
authors.initials: S
authors.lastname: Jancar
mesh_terms: D000818:Animals; D002460:Cell Line; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D015232:Dinoprostone / Q000096:biosynthesis; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018869:Heat-Shock Response / Q000187:drug effects; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000201:enzymology*; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; D051546:Cyclooxygenase 2; D015232:Dinoprostone; D019331:NG-Nitroarginine Methyl Ester