title: Prostaglandins as negative regulators against lipopolysaccharide, lipoteichoic acid, and peptidoglycan-induced inducible nitric oxide synthase/nitric oxide production through reactive oxygen species-dependent heme oxygenase 1 expression in macrophages.
abstract: Although prostaglandins (PGs) were reported to exert proinflammatory and anti-inflammatory effects in macrophages, their action mechanisms remain unclear. The effects of PGs including PGJ2 (J2), Δ-PGJ2 (Δ), 15-deoxy-Δ PGJ2 (15d), PGE2 (E2), and PGF2α (F2α) on lipopolysaccharide (LPS)-, lipoteichoic acid (LTA)-, and peptidoglycan (PGN)-induced inducible nitric oxide (NO) synthase (iNOS)/NO production by RAW264.7 macrophages were investigated. First, we found that induction of cyclooxygenase 2 (COX-2) protein occurred at a time earlier than that of heme oxygenase 1 (HO-1) protein, and the addition of the COX-2 inhibitor NS398 reduced HO-1 protein expression in LPS-, LTA-, and PGN-treated RAW264.7 macrophages. Incubation of RAW264.7 macrophages with the indicated PGs showed that J2, Δ, and 15d significantly induced HO-1 protein expression; however, E2 and F2α did not. Heme oxygenase 1 protein induced by J2, Δ, and 15d was inhibited by the transcriptional inhibitor, actinomycin (Act) D; the translational inhibitor, cycloheximide; and the antioxidant, N-acetyl cysteine (NAC). Increases in intracellular peroxide levels by J2, Δ, and 15d were detected via a 2',7'™-dichlorofluorescein diacetate (DCFH-DA) analysis, and they were prevented by the addition of NAC. In addition, J2, Δ, and 15d produced significant inhibition of LPS-, LTA-, and PGN-induced iNOS protein and NO production by RAW264.7 cells, in accordance with increased HO-1 protein expression. Reductions of LPS-, LTA-, and PGN-induced phosphorylated c-Jun N-terminal kinase, c-Jun protein, and activator protein 1 luciferase activity by J2, Δ, and 15d were identified, and the addition of the HO-1 inhibitor, tin protoporphyrin, reversed the inhibitory effects of Δ and 15d on LPS- and LTA-induced iNOS/NO, phosphorylated c-Jun N-terminal kinase, and c-Jun protein expressions by macrophages. Knockdown of HO-1 protein expression by HO-1 small interfering RNA blocked Δ and 15d inhibition of LPS- and LTA-induced events. Moreover, the compound, cyclopentenone (CP), which mimics the CP moiety of 15d, and its analog cyclohexenone were used, and cyclohexenone showed more potent induction of the HO-1 protein with effective inhibition of LPS-, LTA-, and PGN-induced iNOS/NO production than CP in macrophages. Reactive oxygen species-dependent HO-1 protein expression by PGs, which inhibited LPS-, LTA-, and PGN-induced iNOS/NO production, was identified in macrophages.
authors.affiliation: Division of Nephrology, Chi Mei Medical Center, Tainan, Taiwan.
authors.forename: Chih-Chiang
authors.initials: CC
authors.lastname: Chien
authors.forename: Shing-Chuan
authors.initials: SC
authors.lastname: Shen
authors.forename: Liang-Yo
authors.initials: LY
authors.lastname: Yang
authors.forename: Yen-Chou
authors.initials: YC
authors.lastname: Chen
mesh_terms: D000818:Animals; D002460:Cell Line; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects* / Q000235:genetics; D055785:Gene Knockdown Techniques; D051547:Heme Oxygenase-1 / Q000096:biosynthesis* / Q000235:genetics; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D009569:Nitric Oxide / Q000096:biosynthesis* / Q000235:genetics; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis* / Q000235:genetics; D010457:Peptidoglycan / Q000494:pharmacology*; D011453:Prostaglandins / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013682:Teichoic Acids / Q000494:pharmacology*
chemical_list: D008070:Lipopolysaccharides; D008565:Membrane Proteins; D010457:Peptidoglycan; D011453:Prostaglandins; D017382:Reactive Oxygen Species; D013682:Teichoic Acids; D009569:Nitric Oxide; C009900:lipoteichoic acid; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D051547:Heme Oxygenase-1; C496542:Hmox1 protein, mouse