Kobayashi Sho, Homma Takujiro, Fujii Junichi
Department of Biochemistry and Molecular Biology, Graduate School of Medical Science, Yamagata University, 2-2-2 Iidanishi, Yamagata City, Yamagata, 990-9585, Japan.
Biochem Biophys Rep. 2021 Feb 20;26:100942. doi: 10.1016/j.bbrep.2021.100942. eCollection 2021 Jul.
Nitric oxide (NO) reacts with superoxide to produce peroxynitrite, a potent oxidant and reportedly exerts cytotoxic action. Herein we validated the hypothesis that interaction of NO with superoxide exerts protection against superoxide toxicity using macrophages from mice with a knockout (KO) of inducible NO synthase (NOS2) and superoxide dismutase 1 (SOD1), either individually or both. While no difference was observed in viability between wild-type (WT) and NOS2KO macrophages, SOD1KO and SOD1-and NOS2-double knockout (DKO) macrophages were clearly vulnerable and cell death was observed within four days. A lipopolysaccharide (LPS) treatment induced the formation of NOS2, which resulted in NO production in WT and these levels were even higher in SOD1KO macrophages. The viability of the DKO macrophages but not SOD1KO macrophages were decreased by the LPS treatment. Supplementation of NOC18, a NO donor, improved the viability of SOD1KO and DKO macrophages both with and without the LPS treatment. The NOS2 inhibitor nitro-l-arginine methyl ester consistently decreased the viability of LPS-treated SOD1KO macrophages but not WT macrophages. Thus, in spite of the consequent production of peroxynitrite in LPS-stimulated macrophages, the coordinated elevation of NO appears to exert anti-oxidative affects by coping with superoxide cytotoxicity upon conditions of inflammatory stimuli.
一氧化氮（NO）与超氧化物反应生成过氧亚硝酸盐，这是一种强效氧化剂，据报道具有细胞毒性作用。在此，我们验证了以下假设：使用诱导型一氧化氮合酶（NOS2）基因敲除（KO）和超氧化物歧化酶1（SOD1）基因敲除的小鼠巨噬细胞，单独或同时缺失这两种基因，NO与超氧化物的相互作用可对超氧化物毒性起到保护作用。野生型（WT）巨噬细胞和NOS2基因敲除巨噬细胞的活力未观察到差异，而SOD1基因敲除巨噬细胞以及SOD1和NOS2双基因敲除（DKO）巨噬细胞明显脆弱，在四天内观察到细胞死亡。脂多糖（LPS）处理诱导了NOS2的形成，导致WT巨噬细胞产生NO，且SOD1基因敲除巨噬细胞中的这些水平更高。LPS处理降低了DKO巨噬细胞的活力，但未降低SOD1基因敲除巨噬细胞的活力。补充NO供体NOC18可提高LPS处理和未处理的SOD1基因敲除巨噬细胞以及DKO巨噬细胞的活力。NOS2抑制剂硝基-L-精氨酸甲酯持续降低LPS处理的SOD1基因敲除巨噬细胞的活力，但未降低WT巨噬细胞的活力。因此，尽管在LPS刺激的巨噬细胞中会产生过氧亚硝酸盐，但在炎症刺激条件下，NO的协同升高似乎通过应对超氧化物细胞毒性发挥抗氧化作用。
