Invasion of brain microvascular endothelial cells by group B streptococci
Invasion of brain microvascular endothelial cells by group B streptococci
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DOI：
10.1128/iai.65.12.5074-5081.1997
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发表时间：
1997-12-01
影响因子：
3.1
通讯作者：
Rubens, CE
中科院分区：
文献类型：
--
作者：
Nizet, V;Kim, KS;Rubens, CE
B族链球菌（GBS）是新生儿脑膜炎的主要病因，尽管脑膜炎是在菌血症后发生的，但GBS离开血流并进入中枢神经系统（CNS）的确切机制尚不清楚。我们假设GBS产生脑膜炎是因为其具有独特的侵入人脑微血管内皮细胞（BMEC）的能力，构成血脑屏障的单细胞层。为了验证这一假设，我们开发了一种体外模型，其中BMEC分离自人，通过猿猴病毒40转化永生化，并在组织培养单层中繁殖。电子显微镜观察GBS对BMEC单层的侵袭。细胞内的GBS被发现在膜结合的空泡内，这表明生物体诱导其自身的内吞摄取。用庆大霉素保护试验定量GBS对BMEC的侵袭，占CNS分离株大多数的血清型III菌株比来自其他常见GBS血清型的菌株更有效地侵袭BMEC。GBS在BMEC内存活20 h以上，无明显的细胞内复制，GBS侵入BMEC需要活跃的细菌DNA、RNA和蛋白质的合成，以及真核细胞骨架的微丝和微管元件，GBS的多糖包膜减弱了生物体的侵袭能力。在高细菌密度下，GBS侵入BMEC伴随着细胞损伤的证据;这种细胞毒性与细菌产生的β-溶血素相关。最后，GBS表现出跨在Transwell膜上生长的完整极性BMEC单层的转胞吞作用。GBS侵入BMEC可能是脑膜炎发病机制的主要步骤，使细菌通过胞吞作用或通过损伤和破坏内皮血脑屏障进入CNS。
Group B streptococci (GBS) are the leading cause of meningitis in newborns, Although meningitis develops following bacteremia, the precise mechanism or mechanisms whereby GBS leave the bloodstream and gain access to the central nervous system (CNS) are not known, We hypothesized that GBS produce meningitis because of a unique capacity to invade human brain microvascular endothelial cells (BMEC), the single-cell layer which constitutes the blood-brain barrier. In order to test this hypothesis, we developed an in vitro model with BMEC isolated from a human, immortalized by simian virus 40 transformation, and propagated in tissue culture monolayers. GBS invasion of BMEC monolayers was demonstrated by electron microscopy. Intracellular GBS were found within membrane-bound vacuoles, suggesting the organism induced its own endocytic uptake. GBS invasion of BMEC was quantified with a gentamicin protection assay, Serotype III strains, which account for the majority of CNS isolates, invaded BMEC more efficiently than strains from other common GBS serotypes. GBS survived within BMEC for up to 20 h without significant intracellular replication, GBS invasion of BMEC required active bacterial DNA, RNA, and protein synthesis, as,yell as microfilament and microtubule elements of the eukaryotic cytoskeleton, The polysaccharide capsule of GBS attenuated the invasive ability of the organism. At high bacterial densities, GBS invasion of BMEC was accompanied by evidence of cellular injury; this cytotoxicity was correlated to beta-hemolysin production by the bacterium, Finally, GBS demonstrated transcytosis across intact, polar BMEC monolayers grown on Transwell membranes. GBS invasion of BMEC may be a primary step in the pathogenesis of meningitis, allowing bacteria access to the CNS by transcytosis or by injury and disruption of the endothelial blood-brain barrier.