Jong A Y, Stins M F, Huang S H, Chen S H, Kim K S
Divisions of Hematology-Oncology, Childrens Hospital Los Angeles, Los Angeles, California 90027, USA.
Infect Immun. 2001 Jul;69(7):4536-44. doi: 10.1128/IAI.69.7.4536-4544.2001.
Candida albicans is an opportunistic pathogen, which primarily affects neonates and immunocompromised individuals. The pathogen can invade the central nervous system, resulting in meningitis. At present, the pathogenesis of C. albicans meningitis is unclear. We used an in vitro model of the human blood-brain barrier to investigate the interaction(s) of C. albicans with human brain microvascular endothelial cells (BMEC). Binding of C. albicans to human BMEC was time and inoculum dependent. Invasion of C. albicans into human BMEC was demonstrated by using an enzyme-linked immunosorbent assay based on fluorescent staining of C. albicans with calcoflour. In contrast, avirulent Candida mutant strains and nonpathogenic yeast Saccharomyces cerevisiae were not able to bind and invade human BMEC. Morphological studies revealed that on association with human BMEC, C. albicans formed germ tubes and was able to bud intracellularly. Transmission electron microscopy showed various stages of C. albicans interactions with human BMEC, e.g., pseudopod-like structures on human BMEC membrane and intracellular vacuole-like structures retaining C. albicans. Of interest, C. albicans was able to bud and develop pseudohyphae inside human BMEC without apparent morphological changes of the host cells. In addition, C. albicans penetrates through human BMEC monolayers without a detectable change in transendothelial electrical resistance and inulin permeability. This is the first demonstration that C. albicans is able to adhere, invade, and transcytose across human BMEC without affecting monolayer integrity. A complete understanding of the interaction(s) of C. albicans with human BMEC should contribute to the understanding of the pathogenic mechanism(s) of C. albicans meningitis.
白色念珠菌是一种机会致病菌，主要影响新生儿和免疫功能低下的个体。该病原体可侵入中枢神经系统，导致脑膜炎。目前，白色念珠菌脑膜炎的发病机制尚不清楚。我们使用人血脑屏障的体外模型来研究白色念珠菌与人脑微血管内皮细胞（BMEC）之间的相互作用。白色念珠菌与人BMEC的结合具有时间和接种量依赖性。通过基于用荧光增白剂对白色念珠菌进行荧光染色的酶联免疫吸附测定，证明了白色念珠菌侵入人BMEC。相比之下，无毒的念珠菌突变株和非致病性酵母酿酒酵母不能结合和侵入人BMEC。形态学研究表明，与人类BMEC结合时，白色念珠菌形成芽管并能够在细胞内出芽。透射电子显微镜显示了白色念珠菌与人BMEC相互作用的各个阶段，例如人BMEC膜上的伪足样结构和保留白色念珠菌的细胞内空泡样结构。有趣的是，白色念珠菌能够在人BMEC内出芽并形成假菌丝，而宿主细胞没有明显的形态变化。此外，白色念珠菌穿透人BMEC单层，而跨内皮电阻和菊粉通透性没有可检测到的变化。这是首次证明白色念珠菌能够在不影响单层完整性的情况下粘附、侵入并穿越人BMEC。对白色念珠菌与人BMEC相互作用的全面理解应有助于理解白色念珠菌脑膜炎的致病机制。
