Marcinkiewicz J, Chain B, Nowak B, Grabowska A, Bryniarski K, Baran J
Department of Immunology, Jagiellonian University Medical College, Cracow, Poland.
Inflamm Res. 2000 Jun;49(6):280-9. doi: 10.1007/PL00000208.
HOCl, a major bactericidal product of neutrophil MPO-halide system reacts with taurine to form taurine chloramine (TauCl), a less toxic anti-inflammatory mediator. Recently, it has been reported that HOCl may also react with nitrite (NO2-), a major end-product of nitric oxide (NO) metabolism, to form very active oxidant, nitryl chloride (NO2Cl). The present study was conducted to elucidate the effect of nitrite on bactericidal and some immunoregulatory properties of HOCl and TauCl.
TauCl was prepared from NaOCl and taurine. The reaction was carried out at pH 5.0 and pH 7.4, in the presence or absence of nitrite. All reactions were monitored by UV absorption spectra.
Bactericidal activity of HOCl and TauCl in the presence of nitrite was tested by incubation of E. coli with the compounds and determined by the pour-plate method. To test the effect of the compounds on activity of inflammatory cells, murine peritoneal neutrophils (PMN) and macrophages were used. The cells were activated in vitro with either LPS, IFN-gamma or zymosan and the production of following mediators was measured: reactive oxygen species using luminol-dependent chemiluminescence; nitric oxide by Griess reaction; TNF-alpha using capture ELISA. In addition, we tested the effect of HOCl and TauCl on activity of myeloperoxidase (MPO).
At physiological pH nitrite reacts with HOCl but not with TauCl. This reaction was abolished in the presence of taurine. Nitrite prevented HOCl-mediated bacterial killing, inhibition of MPO activity, cellular cytotoxicity and inhibition of TNF-alpha production. Nitrite did not affect any activity of TauCl.
We have shown that nitrite may react in vitro with HOCl but not with TauCl, to form new biologically active product(s). We did not confirm the hypothesis that a product of HOCl reaction with nitrite is more toxic than HOCl. To the contrary, we found that nitrite diminished bactericidal and immunoregulatory properties of HOCl. In vivo, nitrite will also compete with taurine for reaction with PMN-released HOCl. Nevertheless, due to high concentration of taurine in PMN cytosol, formation of TauCl will be a major regulatory mechanism of MPO-halide-system.
次氯酸（HOCl）是中性粒细胞髓过氧化物酶 - 卤化物系统的主要杀菌产物，它与牛磺酸反应生成毒性较小的抗炎介质氯胺牛磺酸（TauCl）。最近有报道称，HOCl还可能与一氧化氮（NO）代谢的主要终产物亚硝酸盐（NO2-）反应，形成活性很强的氧化剂硝酰氯（NO2Cl）。本研究旨在阐明亚硝酸盐对HOCl和TauCl的杀菌及一些免疫调节特性的影响。
氯胺牛磺酸由次氯酸钠和牛磺酸制备。反应在pH 5.0和pH 7.4条件下进行，有无亚硝酸盐存在。所有反应通过紫外吸收光谱监测。
通过将大肠杆菌与化合物孵育，采用倾注平板法测定亚硝酸盐存在下HOCl和TauCl的杀菌活性。为测试化合物对炎症细胞活性的影响，使用了小鼠腹腔中性粒细胞（PMN）和巨噬细胞。细胞用脂多糖、γ干扰素或酵母聚糖体外激活，并测量以下介质的产生：使用鲁米诺依赖性化学发光法检测活性氧；通过格里斯反应检测一氧化氮；使用捕获ELISA检测肿瘤坏死因子 -α。此外，我们测试了HOCl和TauCl对髓过氧化物酶（MPO）活性的影响。
在生理pH值下，亚硝酸盐与HOCl反应，但不与TauCl反应。在牛磺酸存在下，该反应被消除。亚硝酸盐可防止HOCl介导的细菌杀伤、MPO活性抑制、细胞毒性以及肿瘤坏死因子 -α产生的抑制。亚硝酸盐不影响TauCl的任何活性。
我们已表明，亚硝酸盐在体外可能与HOCl反应，但不与TauCl反应，形成新的生物活性产物。我们没有证实HOCl与亚硝酸盐反应的产物比HOCl毒性更大的假设。相反，我们发现亚硝酸盐会降低HOCl的杀菌和免疫调节特性。在体内，亚硝酸盐也会与牛磺酸竞争，与PMN释放的HOCl反应。然而，由于PMN胞质溶胶中牛磺酸浓度较高，氯胺牛磺酸的形成将是MPO - 卤化物系统的主要调节机制。
