Comparison of the responses of peritoneal macrophages from Japanese flounder (Paralichthys olivaceus) against high virulent and low virulent strains of Edwardsiella tarda
Comparison of the responses of peritoneal macrophages from Japanese flounder (Paralichthys olivaceus) against high virulent and low virulent strains of Edwardsiella tarda
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DOI：
10.1016/j.fsi.2007.11.001
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发表时间：
2008-02-01
影响因子：
4.7
通讯作者：
Oda, Tatsuya
中科院分区：
文献类型：
--
作者：
Ishibe, Keiko;Osatomi, Kiyoshi;Oda, Tatsuya
对牙鲆的体内感染研究表明，经腹腔注射后，迟缓爱德华菌毒力菌株（NUF251）在肾脏和肝胰腺的活细胞数量逐渐增加，而两株毒力菌株（NUF194）的活细胞数量没有增加。为了深入了解该菌株的毒力因素，我们在体外比较了牙鲆（P. olivaceus）腹膜巨噬细胞对这些菌株的吞噬作用、杀菌活性和化学发光（CL）反应中活性氧（ROS）的产生。显微镜观察发现，这两种菌株均被腹膜吞噬。每个巨噬细胞的平均摄食细菌数量在这些菌株之间没有显著差异。吞噬后9小时内，高毒力菌株在巨噬细胞内的活细胞数量逐渐增加，而低毒力菌株在巨噬细胞内没有明显的复制。这些结果表明，毒力强的菌株具有在巨噬细胞内存活和复制的能力，而低毒力的菌株则没有这种能力。当腹膜巨噬细胞暴露于经调理的弱毒迟缓e菌株时，诱导CL反应迅速增加。然而，高毒力菌株仅引起背景水平的CL反应。随后用肉豆蔻酸酯佛博尔刺激，巨噬细胞暴露于毒力较强的迟缓E.菌株的CL反应明显高于暴露于低毒力的迟缓E.菌株的CL反应。这些结果表明，在吞噬过程中，尽管活性氧生成系统仍然能够对其他刺激做出反应，但毒力强的迟芽胞杆菌可以阻止活性氧生成系统的激活。毒力菌株显著降低了黄嘌呤/黄嘌呤氧化酶系统诱导的CL反应，而低毒力菌株几乎没有影响。毒力菌株对H2O2的抗性高于低毒力菌株。我们的研究结果表明，该毒力菌株对活性氧具有高度抗性，这种能力可能使该生物能够在吞噬细胞内存活和繁殖，并可能在体内感染时在宿主体内传播该菌株。(c) 2007 Elsevier Ltd.版权所有。
In vivo infection studies in Japanese flounder (Paralichthys olivaceus) demonstrated that the number of viable cells of the virulent strain (NUF251) of Edwardsiella tarda increased gradually in kidney and hepato-pancreas after intraperitoneal injection, but the tow virulent strain (NUF194) did not. To gain insight into the virulence factors of E. tarda, in vitro responses of Japanese flounder (P. olivaceus) peritoneal macrophages to these strains were compared in terms of phagocytosis, bactericidal activity, and reactive oxygen species (ROS) generation as measured by chemiluminescence (CL) responses. Microscopic observation revealed that these two strains of E. tarda were phagocytosed by the peritoreal. macrophages, and there was no significant difference in the mean numbers of ingested bacteria per macrophage between these strains. A gradual increase in the number of viable cells of the highly virulent strain within macrophages was observed during 9 h post-phagocytosis, whereas no significant replication of the low virulent strain within macrophages was detected. These results suggest that the virulent strain of E. tarda has an ability to survive and replicate within macrophages, while the low virulent strain has no such ability. When the peritoneal macrophages were exposed to the opsonized tow virulent E. tarda strain, a rapid increase in CL response was induced. However, the highly virulent strain caused only background level of CL response. By the subsequent stimulation with phorbol myristate acetate, the macrophages exposed to the virulent E. tarda strain showed extremely higher CL response than that of the one exposed to the low virulent E. tarda strain. These results suggest that the virulent E. tarda prevents the activation of ROS generation system during phagocytosis, though the system is still capable of responding to other stimulation. The virulent strain significantly reduced the CL response induced by xanthine/xanthine oxidase system, while the low virulent strain had almost no effect. Furthermore, the virulent strain showed greater resistance to H2O2 than the low virulent strain. Our results suggest that the virulent strain of E. tarda is highly resistant to ROS, and such ability might allow the organism to survive and multiply within phagocytes, and may serve to disseminate E. tarda throughout the host during in vivo infection. (c) 2007 Elsevier Ltd. All rights reserved.