Inhibitory action of nitric oxide on circulating tumor necrosis factor-induced NF-κB activity and COX-2 transcription in the endothelium of the brain capillaries
Inhibitory action of nitric oxide on circulating tumor necrosis factor-induced NF-κB activity and COX-2 transcription in the endothelium of the brain capillaries
复制标题
DOI：
10.1093/jnen/60.9.893
复制
发表时间：
2001-09-01
影响因子：
3.2
通讯作者：
Rivest, S
中科院分区：
文献类型：
--
作者：
Blais, V;Rivest, S
循环肿瘤坏死因子 α (TNF-α) 对丝裂原激活蛋白激酶具有深远的刺激影响，从而导致核因子 kappa B (NF-kappaB) 活性和血脑屏障 (BBB) 相关细胞中环氧合酶 2 (COX-2) 基因的转录。本研究调查了这样的假设：一氧化氮 (NO) 作为 TNF 诱导的脑毛细血管内皮细胞中 NF-κB 信号传导和 COX-2 转录的内源性调节剂。为此，用NO合酶（NOS）N（G）-硝基-L-精氨酸甲酯（L-NAME）的非选择性抑制剂对大鼠进行预处理，并在静脉注射后15、45和90分钟（min）处死大鼠。注射重组大鼠TNF-α。抑制因子 kappaB α (I kappaB α) 的从头表达用作 NF-kappaB 活性的指标，而通过原位杂交结合免疫组织化学评估整个脑中 COX-2 mRNA 的诱导情况。单次静脉注射TNF推注引起I kappaB α转录物首先沿着大动脉和小毛细血管快速表达，然后在跨脑实质的小胶质细胞内快速表达。促炎细胞因子还引发了 COX-2 基因的强烈转录激活，该基因对脑内皮细胞非常特异，正如使用针对冯·维勒布兰德因子的抗血清的双重标记所揭示的那样。 NO合成的抑制本身并不会激活这些促炎分子，但它增强了血脑屏障中循环TNF-α的作用；在接受 L-NAME 和 TNF-α 治疗的动物的微血管相关细胞中，I kappaB α 和 COX-2 信号显着高于仅接受促炎细胞因子攻击的动物。用特定一氧化氮合酶抑制剂治疗的大鼠提供的证据表明，这些作用是通过组成型内皮一氧化氮合酶（eNOS）而不是诱导形式介导的。这些结果表明，eNOS 衍生的 NO 作为 TNF-α 诱导的脑毛细血管内皮细胞中 NF-κB 活性和 COX-2 转录的内源性抑制剂。 NO 对这些促炎信号转导事件的自动调节反馈可能是防止系统免疫挑战期间 BBB 细胞中发生过度反应的重要因素。
Circulating tumor necrosis factor alpha (TNF-alpha) has a profound stimulatory influence on mitogen-activated protein kinases that lead to nuclear factor kappa B (NF-kappaB) activity and transcription of the cyclooxygenase 2 (COX-2) gene in cells associated with the blood-brain barrier (BBB). This study investigated the hypothesis that nitric oxide (NO) acts as an endogenous modulator of TNF-induced NF-kappaB signaling and COX-2 transcription in the endothelium of the cerebral capillaries. To this end, rats were pretreated with the nonselective inhibitor of NO synthase (NOS) N(G)-nitro-L-arginine methyl ester (L-NAME) and killed 15, 45, and 90 minutes (min) after an i.v. injection of recombinant rat TNF-alpha. De novo expression of the inhibitory factor kappa B alpha (I kappaB alpha) was used as an index of NF-kappaB activity, whereas COX-2 mRNA induction was evaluated throughout the bra-in by in situ hybridization combined with immunohistochemistry. A single i.v. bolus of TNF caused a rapid expression Of I kappaB alpha transcript first along large arterioles and small capillaries and thereafter within microglia across the brain parenchyma. The proinflammatory cytokine also provoked a strong transcriptional activation of the COX-2 gene that was quite specific to the cerebral endothelium as revealed by dual labeling using an antisera directed against the von Willebrand factor. Inhibition of NO synthesis did not by itself activate these proinflammatory molecules, but it enhanced the effects of circulating TNF-alpha in the BBB; the I kappaB alpha and COX-2 signal was significantly higher in microvascular-associated cells of animals that received both L-NAME and TNF-alpha treatments than those challenged with the proinflammatory cytokine alone. Rats treated with specific NOS inhibitors provided the evidence that these effects were mediated via the constitutive endothelial NOS (eNOS) and not the inducible form. These results indicate that eNOS-derived NO acts as an endogenous inhibitor of TNF-alpha -induced NF-kappaB activity and COX-2 transcription in the endothelium of the cerebral capillaries. This autoregulatory feedback of NO on these proinflammatory signal transduction events may be an essential element to prevent an exaggerated response that takes place in cells of the BBB during systemic immune challenges.