Sareila O, Korhonen R, Auvinen H, Hämäläinen M, Kankaanranta H, Nissinen E, Moilanen E
The Immunopharmacology Research Group, Medical School, University of Tampere and Research Unit, Tampere University Hospital, Tampere, Finland.
Br J Pharmacol. 2008 Nov;155(6):884-95. doi: 10.1038/bjp.2008.328. Epub 2008 Aug 18.
Levosimendan is used in the treatment of decompensated heart failure. It increases the contractility of the myocardium by sensitizing troponin C to calcium. In addition, levosimendan has been reported to have beneficial effects in experimental models of septic shock. Because heart failure and sepsis have been associated with excessive nitric oxide (NO) production through inducible NOS (iNOS), we investigated the effects of the simendans on NO production and iNOS expression and on generation of pro-inflammatory cytokines.
Macrophages and fibroblasts were exposed to inflammatory stimuli to induce iNOS expression. Proteins were measured by western blot and mRNA expression was determined by quantitative RT-PCR. Promoter activity and nuclear factor-kappaB (NF-kappaB) and the gamma-activated site (GAS; binding site for signal transducer and activator of transcription 1; STAT1)-mediated transcription were investigated using luciferase reporter constructs. Cytokines tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) were measured by ELISA.
Levosimendan and dextrosimendan decreased NO production in a dose-dependent manner in cells exposed to inflammatory stimuli. The simendans decreased iNOS protein and mRNA expression but did not affect iNOS mRNA decay. These compounds decreased iNOS promoter activity and inhibited NF-kappaB-mediated transcription but not that mediated by STAT1/GAS. The simendans reduced IL-6 production slightly but they had no effect on TNF-alpha synthesis.
The simendans downregulated NF-kappaB-dependent transcription and decreased iNOS promoter activity, iNOS expression and NO production. These mechanisms may contribute to their beneficial clinical effects.
左西孟旦用于治疗失代偿性心力衰竭。它通过使肌钙蛋白C对钙敏感来增加心肌收缩力。此外，据报道左西孟旦在脓毒症休克实验模型中具有有益作用。由于心力衰竭和脓毒症与通过诱导型一氧化氮合酶（iNOS）产生过量一氧化氮（NO）有关，我们研究了西孟旦类药物对NO产生、iNOS表达以及促炎细胞因子生成的影响。
使巨噬细胞和成纤维细胞暴露于炎性刺激以诱导iNOS表达。通过蛋白质印迹法测定蛋白质，通过定量逆转录聚合酶链反应（RT-PCR）测定mRNA表达。使用荧光素酶报告基因构建体研究启动子活性以及核因子-κB（NF-κB）和γ-活化位点（GAS；信号转导子和转录激活子1（STAT1）的结合位点）介导的转录。通过酶联免疫吸附测定法（ELISA）测量细胞因子肿瘤坏死因子-α（TNF-α）和白细胞介素-6（IL-6）。
在暴露于炎性刺激的细胞中，左西孟旦和右西孟旦以剂量依赖性方式降低NO产生。西孟旦类药物降低iNOS蛋白和mRNA表达，但不影响iNOS mRNA降解。这些化合物降低iNOS启动子活性并抑制NF-κB介导的转录，但不抑制由STAT1/GAS介导的转录。西孟旦类药物略微降低IL-6产生，但对TNF-α合成无影响。
西孟旦类药物下调NF-κB依赖性转录并降低iNOS启动子活性、iNOS表达和NO产生。这些机制可能有助于其有益的临床效果。
