Endothelial Dysfunction and Vascular Inflammation

用人eNOS转染类单胚U937细胞产生了响应钙离子载体产生NO的细胞系，但在静息状态下产生很少或不产生NO（Blood，1997）。 然而，在用佛波醇-12-乙酸酯-13-肉豆蔻酸酯分化后，eNOS表达细胞通过不依赖于NO的机制产生增加量的TNF α和活性氧。 NOS抑制剂N-ω-甲基-L-精氨酸和eNOS的L-精氨酸结合位点的突变（使其不能产生一氧化氮）都不能阻断eNOS上调TNF α的能力（J Biol Chem，2000）。相反，与超氧化物歧化酶共转染或eNOS的NADPH结合位点的缺失完全阻止eNOS上调TNF α的产生。这些结果表明，eNOS可以通过NO（J Immunol，1994; J Biol Chem，1997）和基于活性氧的信号转导途径（J Biol Chem，2000）来调节炎症反应。 由eNOS产生的超氧化物显示通过p42/44 MAPK活化上调TNF α（J Biol Chem，2001）。 显示Sp1作为NO传感器，通过近端Sp启动子结合位点下调内皮细胞中的eNOS（J Biol Chem，2003）。 镰状细胞病的特征是血管系统中的氧化剂和炎性应激，即使在没有急性危象的情况下也是如此（Blood，2004）。镰状细胞病的循环应激与血小板中的基因表达和精氨酸代谢异常相关（Circulation，2007） 防止慢性血管损伤表型发展的NO的抗增殖作用与p38 MAPK活化和p21 mRNA稳定化以及随后通过CDE/CD 45近端启动子位点下调polo样激酶1有关（BMC Genomics，2005; J Biol Chem，2006）。 NO和过氧化物酶体增殖物激活受体（PPARs）都能保护内皮细胞并调节其功能。因此，我们使用人脐静脉和杂交EA.hy926内皮细胞测试了这些信号通路之间的串扰（FASEB J，2007）。NO通过p38 MAPK依赖的信号转导途径激活PPARgamma。这种串扰机制可能有助于NO在血管中的抗炎和细胞保护作用，并为预防和治疗血管功能障碍提出了新的策略。

Transfection of monoblastoid U937 cells with human eNOS resulted in a cell line that produces NO in response to a calcium ionophore, but little or no NO in the resting state (Blood, 1997). However, after differentiation with phorbol-12-acetate-13-myristate, eNOS expressing cells produced increased amounts of both TNFalpha and reactive oxygen species by mechanisms that were independent of NO. Neither N-omega-methyl-L-arginine, a NOS inhibitor, nor mutation of the L-arginine binding site of eNOS (rendering it incapable of producing nitric oxide) blocked the ability of eNOS to upregulate TNFalpha (J Biol Chem, 2000). Conversely, co-transfection with superoxide dismutare or deletion of the NADPH binding site of eNOS completely prevented eNOS from upregulating TNFalpha production. These results suggest that eNOS can regulate inflammatory responses through both NO (J Immunol, 1994; J Biol Chem, 1997) and reactive oxygen species-based signal transduction pathways (J Biol Chem, 2000). Superoxide produced by eNOS was shown to upregulate TNFalpha via p42/44 MAPK activation (J Biol Chem, 2001). Sp1 was shown to act as a NO sensor, down regulating eNOS in endothelial cells via a proximal Sp promoter-binding site (J Biol Chem, 2003). Sickle cell disease was characterized by oxidant and inflammatory stress in the vasculature, even in the absence of an acute crisis (Blood, 2004). Circulatory stress in sickle cell disease was associated with gene expression and arginine metabolism abnormalities in platelets (Circulation, 2007) Anti-proliferative effects of NO that prevent the development of a chronic vascular injury phenotype was linked to p38 MAPK activation and p21 mRNA stabilization with subsequent down regulation of polo-like kinase 1 through a CDE/CHR proximal promoter site (BMC Genomics, 2005; J Biol Chem, 2006). Both NO and peroxisome proliferator-activated receptors (PPARs) protect the endothelium and regulate its function. Therefore, we tested for crosstalk between these signaling pathways using human umbilical vein and hybrid EA.hy926 endothelial cells (FASEB J, 2007). PPARgamma was activated by NO through a p38 MAPK dependent signal transduction pathway. This crosstalk mechanism may contribute to the anti-inflammatory and cytoprotective effects of NO in the vasculature and suggests new strategies for preventing and treating vascular dysfunction.