TLR4 Recognizes Pseudallescheria boydii Conidia and Purified Rhamnomannans
TLR4 Recognizes Pseudallescheria boydii Conidia and Purified Rhamnomannans
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DOI：
10.1074/jbc.m110.181255
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发表时间：
2010-12-24
影响因子：
4.8
通讯作者：
Bozza, Marcelo T.
中科院分区：
文献类型：
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作者：
Figueiredo, Rodrigo T.;Fernandez, Patricia L.;Bozza, Marcelo T.
Pseudallescheria boydii (Scedosporium apiospermum) 是一种广泛存在于环境中的腐生真菌，最近在免疫功能低下和免疫功能正常的宿主中成为局部和播散性感染（特别是足菌肿）的病原体。我们之前已经证明，来自博伊迪氏菌的高度纯化的α-葡聚糖通过Toll样受体TLR2激活巨噬细胞，然而，巨噬细胞识别博伊迪氏菌的机制在很大程度上是未知的。在这项工作中，我们研究了先天免疫受体在识别博伊迪氏菌中的作用。巨噬细胞对博氏疟原虫分生孢子和菌丝作出反应，分泌促炎细胞因子。 P. boydii 分生孢子激活巨噬细胞需要功能性 MyD88、TLR4 和 CD14，而菌丝的刺激则独立于 TLR4 和 TLR2 信号传导。从 P. boydii 分生孢子中去除肽汉姆甘露聚糖消除了巨噬细胞对细胞因子的诱导。获得了高度富集鼠李甘露聚糖的级分，并通过 NMR、高性能 TLC 和 GC-MS 进行了表征。源自 P. boydii 的鼠李甘露聚糖的制备引发巨噬细胞释放细胞因子，以及 MAPK 磷酸化和 I kappa B α 降解。 P. boydii 衍生的鼠李甘露聚糖诱导的细胞因子释放依赖于 TLR4 识别，并且需要鼠李甘露聚糖的非还原末端单位的存在，但不需要来自肽鼠李甘露聚糖的 O-连接寡糖。这些结果暗示TLR4识别博伊迪氏菌分生孢子并且这种识别至少部分归因于博伊迪氏菌表面表达的鼠李甘露聚糖。
Pseudallescheria boydii (Scedosporium apiospermum) is a saprophytic fungus widespread in the environment, and has recently emerged as an agent of localized as well as disseminated infections, particularly mycetoma, in immunocompromised and immunocompetent hosts. We have previously shown that highly purified alpha-glucan from P. boydii activates macrophages through Toll-like receptor TLR2, however, the mechanism of P. boydii recognition by macrophage is largely unknown. In this work, we investigated the role of innate immune receptors in the recognition of P. boydii. Macrophages responded to P. boydii conidia and hyphae with secretion of proinflammatory cytokines. The activation of macrophages by P. boydii conidia required functional MyD88, TLR4, and CD14, whereas stimulation by hyphae was independent of TLR4 and TLR2 signaling. Removal of peptidorhamnomannans from P. boydii conidia abolished induction of cytokines by macrophages. A fraction highly enriched in rhamnomannans was obtained and characterized by NMR, high performance TLC, and GC-MS. Preparation of rhamnomannans derived from P. boydii triggered cytokine release by macrophages, as well as MAPKs phosphorylation and I kappa B alpha degradation. Cytokine release induced by P. boydii-derived rhamnomannans was dependent on TLR4 recognition and required the presence of non-reducing end units of rhamnose of the rhamnomannan, but not O-linked oligosaccharides from the peptidorhamnomannan. These results imply that TLR4 recognizes P. boydii conidia and this recognition is at least in part due to rhamnomannans expressed on the surface of P. boydii.