氧化鐵奈米粒子對脂多醣活化小鼠微膠細胞功能之作用

The Effect of Iron Oxide Nanoparticles on the Functionality of Murine Microglia Stimulated with Lipopolysaccharide

鍾姄(Min-Chun Chung)

指導教授 ： 詹東榮

國立臺灣大學/獸醫專業學院/獸醫學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.02278

摘要

氧化鐵奈米粒子普遍應用於中樞核磁共振成像的對比劑。微膠細胞為中樞神經系統中主要的免疫細胞，具有監督外來抗原入侵及引起適當炎症反應以消滅外來病原之功能。本研究的主旨在於探討當中樞感染與小鼠初代微膠細胞大量活化下，氧化鐵奈米粒子對其免疫功能是否造成影響。實驗結果顯示氧化鐵奈米粒子濃度低於每毫升100 微克的鐵（100 μg of Fe/mL）時，對小鼠微膠細胞並無細胞毒性，微膠細胞會快速將氧化鐵奈米粒子吞入細胞內，同時抑制微膠細胞的活化、吞噬能力、interleukin-1β (IL-1β)的分泌與IL-1β converting enzyme (ICE) 的活性，但tumor necrosis factor-α (TNF-α) 與TNF-α converting enzyme (TACE) 卻不受影響。此外，被攝入的氧化鐵奈米粒子會進入微膠細胞內的溶體，同時造成溶體鹼化與膜通透性上升，並抑制溶體分解蛋白質的能力及cathepsin B酵素的活性。進一步探討氧化鐵奈米粒子抑制免疫功能與溶體受損間的關係，顯示氧化鐵奈米粒子抑制cathepsin B的活性而減少ICE活性與IL-1β的分泌。綜合上述，本研究結果指出氧化鐵奈米粒子會抑制微膠細胞防禦性免疫功能，且傷害溶體正常功能，顯示氧化鐵奈米粒子抑制微膠細胞對抗病原感染能力。

關鍵字

介白素 ； 氧化鐵奈米粒子 ； 脂多醣 ； 溶體 ； 微膠細胞

並列摘要

Superparamagnetic iron oxide nanoparticles have been employed as magnetic resonance imaging contrast agents for a variety of diagnostic applications, including the imaging of the central nervous system (CNS). As the central resident immune cells with macrophage-like functions, microglia are the dominant cells responsible for managing foreign materials invading the CNS. The objective of this study was to investigate the potential effect of iron oxide nanoparticles on functional activities of primary murine microglia stimulated with lipopolysaccharide (LPS). The results showed that iron oxide nanoparticles at concentrations < 100 μg of Fe/mL did not cause cytotoxicity. Confocal imaging revealed that iron oxide nanoparticles were rapidly and markedly engulfed by microglia. Iron oxide nanoparticles inhibited the expression of the activation marker ionized calcium-binding adaptor molecule-1 and the phagocytic activity of LPS-stimulated microglia. In addition, iron oxide nanoparticles inhibited secretion of interleukin (IL)-1β and IL-1β converting enzyme (ICE) activity, whereas tumor necrosis factor (TNF)-α secretion and TNF-α converting enzyme (TACE) activity were unaltered. Furthermore, internalized iron oxide nanoparticles were accumulated in lysosomes. Iron oxide nanoparticles also impaired lysosome proteolytic and cathepsin B activity, and increased lysosomal membrane permeability and alkalinization. These results suggest that the iron oxide nanoparticles may inhibit the cathepsin B activity, which subsequently suppress the activation of ICE and the secretion of IL-1β. Collectively, the present study demonstrated that iron oxide nanoparticles markedly attenuated the activation and functional activities of LPS-stimulated microglia, suggesting an impaired defense capacity of microglia against gram-negative bacteria.

並列關鍵字

interleukin, iron oxide nanoparticles ； lipopolysaccharide ； lysosome ； microglia

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