Zembowicz A, Vane J R
William Harvey Research Institute, St. Bartholomew's Hospital Medical College, London, England.
Proc Natl Acad Sci U S A. 1992 Mar 15;89(6):2051-5. doi: 10.1073/pnas.89.6.2051.
Toxic shock syndrome toxin 1 (TSST-1) is a Mr 22,000 protein produced by Staphylococcus aureus. It is thought to be the cause of toxic shock syndrome. We investigated the hypothesis that TSST-1 induces nitric oxide (NO) synthase and that the NO formed may be involved in the pathogenesis of toxic shock syndrome. We used the murine monocyte-macrophage cell line J744.2 that responds to TSST-1 and also expresses NO synthase activity upon immunological stimulation. J774.2 macrophages stimulated with TSST-1 (10-100 nM) generated nitrite, a breakdown product of NO, and induced concentration-dependent elevations of cGMP in the pig kidney epithelial cell line (LLC-PK1). This latter effect was due to the generation of L-arginine-derived NO for it was (i) abolished by oxyhemoglobin (10 microM), a scavenger of NO, or by methylene blue (10 microM), an inhibitor of NO-activated guanylate cyclase; (ii) potentiated by superoxide dismutase (100 units/ml), which prolongs the life of NO; (iii) inhibited by NG-monomethyl-L-arginine (0.3 mM), an inhibitor of NO synthase; (iv) significantly decreased when L-arginine (0.4 mM) in the medium was replaced by D-arginine (0.4 mM). Moreover, TSST-1 (100 nM) enhanced the activity of cytosolic NO synthase in J774.2 cells. Hydrocortisone (1 microM) but not indomethacin (5 micrograms/ml) or salicylic acid (5 micrograms/ml) prevented the generation of NO2- and the increases in cGMP levels in LLC-PK1 cells induced by J774.2 cells stimulated with TSST-1. The effects of hydrocortisone were partially reversed by coincubation with RU 486 (1 microM), an antagonist of glucocorticoid receptors. Thus, TSST-1 and perhaps other exotoxins produced by Gram-positive bacteria induce NO synthase and the increased NO formation may contribute to toxic shock syndrome and possibly to changes in the immune responses that accompany infection.
中毒性休克综合征毒素1（TSST-1）是一种由金黄色葡萄球菌产生的分子量为22,000的蛋白质。它被认为是中毒性休克综合征的病因。我们研究了TSST-1诱导一氧化氮（NO）合酶以及所形成的NO可能参与中毒性休克综合征发病机制的假说。我们使用了对TSST-1有反应且在免疫刺激时也表达NO合酶活性的小鼠单核细胞-巨噬细胞系J744.2。用TSST-1（10 - 100 nM）刺激的J774.2巨噬细胞产生了亚硝酸盐（NO的分解产物），并在猪肾上皮细胞系（LLC-PK1）中诱导了cGMP浓度依赖性升高。后一种效应是由于L-精氨酸衍生的NO的产生，因为它（i）被NO清除剂氧合血红蛋白（10 microM）或NO激活的鸟苷酸环化酶抑制剂亚甲蓝（10 microM）消除；（ii）被超氧化物歧化酶（100单位/ml）增强，超氧化物歧化酶可延长NO的寿命；（iii）被NO合酶抑制剂NG-单甲基-L-精氨酸（0.3 mM）抑制；（iv）当培养基中的L-精氨酸（0.4 mM）被D-精氨酸（0.4 mM）取代时显著降低。此外，TSST-1（100 nM）增强了J774.2细胞中胞质NO合酶的活性。氢化可的松（1 microM）而非吲哚美辛（5微克/ml）或水杨酸（5微克/ml）可阻止用TSST-1刺激的J774.2细胞诱导的LLC-PK1细胞中NO2-的产生和cGMP水平的升高。氢化可的松的作用在用糖皮质激素受体拮抗剂RU 486（1 microM）共同孵育后部分逆转。因此，TSST-1以及革兰氏阳性菌产生的其他外毒素可能诱导NO合酶，NO生成增加可能导致中毒性休克综合征，并可能导致伴随感染出现的免疫反应变化。
