Florquin S, Amraoui Z, Dubois C, Decuyper J, Goldman M
Laboratoire Pluridisciplinaire de Recherche Expérimentale Biomédicale, Hôpital Erasme, Université Libre de Bruxelles, Belgium.
J Exp Med. 1994 Sep 1;180(3):1153-8. doi: 10.1084/jem.180.3.1153.
Nitric oxide (NO) synthesis during experimental endotoxemia has been shown to have both deleterious and beneficial effects. In the present study, we analyzed the in vivo production and the regulatory role of NO in the shock syndrome induced by staphylococcal enterotoxin B (SEB) in mice. First, we found that intraperitoneal administration of 100 micrograms SEB in BALB/c mice induced a massive synthesis of NO as indicated by high serum levels of nitrite (NO2-) and nitrate (NO3-) peaking 16 h after SEB injection. The inhibition of NO2- and NO3- release in mice injected with anti-tumor necrosis factor (TNF) and/or anti-interferon gamma (IFN-gamma) monoclonal antibody (mAb) before SEB challenge revealed that both cytokines were involved in SEB-induced NO overproduction. In vitro experiments indicated that NO synthase (NOS) inhibition by N-nitro-L-arginine methyl ester (L-NAME) enhanced IFN-gamma and TNF production by splenocytes in response to SEB. A similar effect was observed in vivo as treatment of mice with L-NAME resulted in increased IFN-gamma and TNF serum levels 24 h after SEB challenge, together with persistent expression of corresponding cytokine mRNA in spleen. The prolonged production of inflammatory cytokines in mice receiving L-NAME and SEB was associated with a 95% mortality rate within 96 h, whereas all mice survived injections of SEB or L-NAME alone. Both TNF and INF-gamma were responsible for the lethality induced by SEB in L-NAME-treated mice as shown by the protection provided by simultaneous administration of anti-IFN-gamma and anti-TNF mAbs. We conclude the SEB induces NO synthesis in vivo and that endogenous NO has protective effects in this model of T cell-dependent shock by downregulating IFN-gamma and TNF production.
实验性内毒素血症期间一氧化氮（NO）的合成已被证明具有有害和有益两种作用。在本研究中，我们分析了NO在小鼠葡萄球菌肠毒素B（SEB）诱导的休克综合征中的体内产生及调节作用。首先，我们发现给BALB/c小鼠腹腔注射100微克SEB可诱导大量NO合成，这表现为血清中亚硝酸盐（NO2-）和硝酸盐（NO3-）水平升高，在SEB注射后16小时达到峰值。在SEB攻击前注射抗肿瘤坏死因子（TNF）和/或抗干扰素γ（IFN-γ）单克隆抗体（mAb）的小鼠中，NO2-和NO3-释放受到抑制，这表明两种细胞因子都参与了SEB诱导的NO过量产生。体外实验表明，N-硝基-L-精氨酸甲酯（L-NAME）抑制一氧化氮合酶（NOS）可增强脾细胞对SEB刺激的IFN-γ和TNF产生。在体内也观察到了类似的效果，因为用L-NAME处理小鼠导致SEB攻击后24小时IFN-γ和TNF血清水平升高，同时脾脏中相应细胞因子mRNA持续表达。接受L-NAME和SEB的小鼠中炎症细胞因子的持续产生与96小时内95%的死亡率相关，而单独注射SEB或L-NAME的所有小鼠均存活。如同时给予抗IFN-γ和抗TNF mAb所提供的保护所示，TNF和INF-γ均是L-NAME处理的小鼠中SEB诱导致死的原因。我们得出结论，SEB在体内诱导NO合成，并且内源性NO通过下调IFN-γ和TNF产生，在这种T细胞依赖性休克模型中具有保护作用。
