炎性细胞因子及脂多糖诱导产生的一氧化氮对人血管内皮细胞的损伤作用

The cytotoxicity of nitric oxide induced by inflammatory cytokine in combination with LPS in endothelial cells

目的 :探讨炎症过程诱生的一氧化氮 (NO)对内皮细胞的损伤及其作用机制。方法 :黄递酶法及Griess法检测可诱导性NO合酶 (iNOS)活性、NO-2 /NO-3 水平 ,RT -PCR技术分析iNOSmRNA的表达 ;同时观察NO产生后对内皮细胞的损伤作用。结果 :IL - 1β 2× 10 5U/L、TNF -α 5× 10 5U/L、γ -INF 2× 10 5U/L联用LPS(10mg/L)可诱导出高浓度NOS合成及NO产生 ,比单用这些细胞因子或LPS诱导的量高两倍多 ,iNOSmRNA的表达水平也显著增加 ;同时MDA及LDH释放率明显增加 ,细胞存活率下降 ,并伴随细胞受损的形态学改变。而单用上述细胞因子或LPS ,以及降低剂量或缩短处理时间 ,其诱生的NOS及NO与正常对照相比P >0 0 5 ;但MDA及LDH释放率仍增加明显。使用 2倍剂量的这些炎性细胞因子或延长处理时间到 48h ,与标准剂量及 2 4h组相比NOS和NO的增加虽不显著 ,但细胞生长受限更明显。NOS抑制剂能阻止NO的产生及其对细胞的损伤作用。结论 :炎性细胞因子及脂多糖可激活iNOS大量表达诱生高浓度的NO 。

AIM: To explore the mechanism underlying inducible nitric oxide (NO) caused injury of endothelial cells during inflammation. METHODS: The activity of iso-enzymes of NO synthase (NOS), NO level and iNOS expression were examined using NADPH method, Griess reaction and RT-PCR, respectively. Furthermore, the lactate dehydrogenase (LDH) release rate, malondialdehyde (MDA) content were also measured. RESULTS:Co-administration of cytokines (TNF-α 5×10 5 U/L, IL-1β 2×10 5 U/L, INF-γ 2×10 5 U/L) and LPS (10 mg/L) caused an obvious increase in NOS activity, NO levels (about two-fold) and a significant injury of the cells. At the same time, a significant increase in iNOS mRNA was also detected. Wheareas, treatment of the cells separately with cytokines or LPS for 24 h had no significant effect on NOS activity and NO level in cell lysates, however, it caused a significant increase in LDH release and MDA content. Also, the effect of cytokines and LPS on cell viability was concentration-and time-dependent. L-NMMA, a inhibitor of NOS, can suppress inducible NO production and protect cells against NO induced injury. CONCLUSION:Co-administration of cytokines (TNF-α, IL-1β and INF-γ) and LPS significant activated iNOS and NO production which, in turn, induced oxidative reaction in endothelial cells.