D'Acquisto F, Maiuri M C, de Cristofaro F, Carnuccio R
Department of Experimental Pharmacology, University of Naples Federico II, Italy.
Naunyn Schmiedebergs Arch Pharmacol. 2001 Aug;364(2):157-65. doi: 10.1007/s002100100435.
Stimulation of J774 macrophages with lipopolysaccharide (LPS) leads to the release of large amounts of prostaglandins (PGs) generated by the inducible isoform of cyclooxygenase (COX-2). Nitric oxide (NO), a pleiotropic free radical, has been demonstrated to modulate the release of a broad range of inflammatory mediators, amongst these PGs. In the present study we investigated the molecular mechanism by which NO affects cyclooxygenase pathway. Incubation of J774 cells with LPS caused an increase of prostaglandin E2 production and COX-2 protein expression which was prevented in a concentration-dependent fashion by pre-incubating cells with sodium nitroprusside (SNP) and S-nitroso-glutathione (GSNO), two NO-generating agents. Electrophoretic mobility shift assay indicated that both NO-generating agents blocked LPS-induced activation of nuclear factor-kappaB (NF-kappaB) by increasing IkappaB-alpha protein expression and blocking nuclear translocation of NF-kappaB subunits p50 and p65. SNP and GSNO also inhibited nuclear factor-interleukin-6 (NF-IL6) activation. These results show for the first time that SNP and GSNO down-regulate LPS-induced COX-2 expression by inhibiting NF-kappaB and NF-IL6 activation and suggest a negative feed-back mechanism that may be important for limiting excessive or prolonged PGs production in pathological events.
用脂多糖（LPS）刺激J774巨噬细胞会导致大量由诱导型环氧化酶（COX-2）产生的前列腺素（PGs）释放。一氧化氮（NO）是一种多效性自由基，已被证明可调节多种炎症介质的释放，其中包括PGs。在本研究中，我们研究了NO影响环氧化酶途径的分子机制。用LPS孵育J774细胞会导致前列腺素E2产量增加和COX-2蛋白表达增加，而预先用硝普钠（SNP）和S-亚硝基谷胱甘肽（GSNO）这两种NO生成剂孵育细胞，则会以浓度依赖的方式阻止这种增加。电泳迁移率变动分析表明，这两种NO生成剂均通过增加IkappaB-α蛋白表达并阻止NF-κB亚基p50和p65的核转位来阻断LPS诱导的核因子-κB（NF-κB）激活。SNP和GSNO还抑制核因子-白细胞介素-6（NF-IL6）激活。这些结果首次表明，SNP和GSNO通过抑制NF-κB和NF-IL6激活来下调LPS诱导的COX-2表达，并提示一种负反馈机制，这可能对限制病理事件中PGs的过度或长期产生很重要。
