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首页> 外文期刊>Infection and immunity >Relative Roles of Pneumolysin and Hydrogen Peroxide from Streptococcus pneumoniae in Inhibition of Ependymal Ciliary Beat Frequency
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Relative Roles of Pneumolysin and Hydrogen Peroxide from Streptococcus pneumoniae in Inhibition of Ependymal Ciliary Beat Frequency

机译：肺炎链球菌肺炎球菌溶血素和过氧化氢在抑制室间隔性纤毛搏动频率中的相对作用

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Ciliated ependymal cells line the ventricular system of the brain and the cerebral aqueducts. This study characterizes the relative roles of pneumolysin and hydrogen peroxide (H2O2) in pneumococcal meningitis, using the in vitro ependymal ciliary beat frequency (CBF) as an indicator of toxicity. We have developed an ex vivo model to examine the ependymal surface of the brain slices cut from the fourth ventricle. The ependymal cells had cilia beating at a frequency of between 38 and 44Hz. D39 (wild-type) and PLN-A (pneumolysin-negative) pneumococci at 108 CFU/ml both caused ciliary slowing. Catalase protected against PLN-A-induced ciliary slowing but afforded little protection from D39. Lysed PLN-A did not reduce CBF, whereas lysed D39 caused rapid ciliary stasis. There was no effect of catalase, penicillin, or catalase plus penicillin on the CBF. H2O2 at a concentration as low as 100 μM caused ciliary stasis, and this effect was abolished by coincubation with catalase. An additive inhibition of CBF was demonstrated using a combination of both toxins. A significant inhibition of CBF at between 30 and 120 min was demonstrated with both toxins compared with either H2O2 (10 μM) or pneumolysin (1 HU/ml) alone. D39 released equivalent levels of H2O2 to those released by PLN-A, and these concentrations were sufficient to cause ciliary stasis. The brain slices did not produce H2O2, and in the presence of 108 CFU of D39 or PLN-A per ml there was no detectable bacterially induced increase of H2O2release from the brain slice. Coincubation with catalase converted the H2O2 produced by the pneumococci to H2O. Penicillin-induced lysis of bacteria dramatically reduced H2O2 production. The hemolytic activity released from D39 was sufficient to cause rapid ciliary stasis, and there was no detectable release of hemolytic activity from the pneumolysin-negative PLN-A. These data demonstrate that D39 bacteria released pneumolysin, which caused rapid ciliary stasis. D39 also released H2O2, which contributed to the toxicity, but this was masked by the more severe effects of pneumolysin. H2O2 released from intact PLN-A was sufficient to cause rapid ciliary stasis, and catalase protected against H2O2-induced cell toxicity, indicating a role for H2O2 in the response. There is also a slight additive effect of pneumolysin and H2O2 on ependymal toxicity; however, the precise mechanism of action and the role of these toxins in pathogenesis remain unclear.
机译：纤毛的室管膜细胞排列在脑和脑导水管的心室系统中。这项研究利用体外室间隔性纤毛跳动频率（CBF）作为毒性指标，表征了肺炎球菌脑膜炎中肺炎球菌溶血素和过氧化氢（H2O2）的相对作用。我们已经开发了一种体外模型，以检查从第四脑室切下的脑片的室管膜表面。室管膜细胞的纤毛跳动频率在38至44Hz之间。 D39（野生型）和PLN-A（肺炎球菌溶血素阴性）肺炎球菌在108 CFU / ml时均可引起睫状体减慢。过氧化氢酶可防止PLN-A诱导的纤毛减慢，但几乎不受D39的保护。溶解的PLN-A不会降低CBF，而溶解的D39会导致快速的睫状体淤滞。过氧化氢酶，青霉素或过氧化氢酶加青霉素对脑血流没有影响。浓度低至100μM的H2O2会导致睫状体淤滞，通过与过氧化氢酶共孵育可以消除这种影响。两种毒素的结合证明了CBF的加性抑制。与单独的H2O2（10μM）或肺炎球菌溶血素（1 HU / ml）相比，两种毒素均在30至120分钟之间显着抑制了CBF。 D39释放的H2O2水平与PLN-A释放的水平相当，这些浓度足以引起睫状体淤滞。脑片不产生H2O2，在每毫升108 CFU D39或PLN-A的存在下，没有可检测到的细菌诱导的H2O2释放增加。与过氧化氢酶共孵育将肺炎球菌产生的H2O2转化为H2O。青霉素诱导的细菌裂解大大降低了H2O2的产生。从D39释放的溶血活性足以引起快速的睫状体淤滞，并且从肺炎球菌溶血素阴性的PLN-A中没有可检测到的溶血活性释放。这些数据表明，D39细菌释放了肺炎球菌溶血素，引起快速的睫状体淤滞。 D39还释放出H2O2，这是造成毒性的原因，但被肺炎球菌溶血素的更严重影响掩盖了。从完整的PLN-A释放的H2O2足以引起快速的睫状体淤滞，并且过氧化氢酶具有针对H2O2诱导的细胞毒性的保护作用，表明H2O2在反应中具有一定作用。肺炎球菌溶血素和过氧化氢对室管膜毒性也有轻微的累加作用。然而，尚不清楚这些毒素在发病机理中的确切作用机理和作用。

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