Hydrogen peroxide contributes to the epithelial cell death induced by the oral mitis group of streptococci.
Hydrogen peroxide contributes to the epithelial cell death induced by the oral mitis group of streptococci.
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DOI：
10.1371/journal.pone.0088136
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发表时间：
2014
期刊：
影响因子：
3.7
通讯作者：
Kawabata S
中科院分区：
文献类型：
--
作者：
Okahashi N;Sumitomo T;Nakata M;Sakurai A;Kuwata H;Kawabata S
链球菌MITS组的成员是人类口腔和上呼吸道共生菌群的正常居民。一些鼠类物种，如口腔链球菌和血链球菌，是人类口腔的主要定殖者。最近，我们发现口腔链球菌产生的过氧化氢(H_2O_2)对人巨噬细胞具有细胞毒性，提示链球菌产生的H_2O_2可能是一种细胞毒素。由于上皮细胞对病原微生物具有物理屏障，我们在这项研究中调查了它们对产H_2O_2链球菌感染的敏感性。口腔沙门氏菌和血链球菌的感染可刺激底特律562、CALU-3和HeLa上皮细胞系的细胞死亡，感染复数大于100。过氧化氢酶是一种催化H_2O_2分解的酶，它抑制口腔沙门氏菌的细胞毒性，而H_2O_2单独能够诱导上皮细胞死亡。此外，缺乏编码丙酮酸氧化酶spxB基因的口腔假单胞菌突变株对底特律562上皮细胞的细胞毒性降低。此外，酶联免疫吸附试验显示，口腔沙门氏菌和过氧化氢均可诱导底特律562上皮细胞产生白介素6。这些结果表明，链球菌过氧化氢对上皮细胞具有细胞毒性，并促进口腔和上呼吸道宿主防御系统的细菌逃避。
Members of the mitis group of streptococci are normal inhabitants of the commensal flora of the oral cavity and upper respiratory tract of humans. Some mitis group species, such as Streptococcus oralis and Streptococcus sanguinis, are primary colonizers of the human oral cavity. Recently, we found that hydrogen peroxide (H2O2) produced by S. oralis is cytotoxic to human macrophages, suggesting that streptococcus-derived H2O2 may act as a cytotoxin. Since epithelial cells provide a physical barrier against pathogenic microbes, we investigated their susceptibility to infection by H2O2-producing streptococci in this study. Infection by S. oralis and S. sanguinis was found to stimulate cell death of Detroit 562, Calu-3 and HeLa epithelial cell lines at a multiplicity of infection greater than 100. Catalase, an enzyme that catalyzes the decomposition of H2O2, inhibited S. oralis cytotoxicity, and H2O2 alone was capable of eliciting epithelial cell death. Moreover, S. oralis mutants lacking the spxB gene encoding pyruvate oxidase, which are deficient in H2O2 production, exhibited reduced cytotoxicity toward Detroit 562 epithelial cells. In addition, enzyme-linked immunosorbent assays revealed that both S. oralis and H2O2 induced interleukin-6 production in Detroit 562 epithelial cells. These results suggest that streptococcal H2O2 is cytotoxic to epithelial cells, and promotes bacterial evasion of the host defense systems in the oral cavity and upper respiratory tracts.
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影响因子：
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