奈米銀對瓶鼻海豚周邊血液單核細胞增殖及細胞激素表現的影響

Abstract

隨著奈米銀科技的蓬勃發展，奈米銀製造量及使用量的日漸增加，有可能會使奈米銀無可避免地污染海洋環境。具有長壽及頂級掠食者特性的海洋哺乳類動物，亦會受到奈米銀污染的影響。因此，奈米銀對海洋哺乳類的負面影響有必要被詳細研究。藉由評估尺寸為20奈米的檸檬酸塗層之奈米銀對周邊血液單核細胞增殖能力以及細胞激素之信使核糖核酸(mRNA)表現量的影響，以探討奈米銀對瓶鼻海豚可能的免疫毒性。本研究的血液樣本來自花蓮遠雄海洋公園六隻圈養的瓶鼻海豚。細胞毒性之實驗結果顯示，暴露於濃度為10 μg/ml的奈米銀二十四及六十小時之後，奈米銀對周邊血液單核細胞會造成細胞毒性。亞致死劑量的奈米銀會抑制致裂原─刀豆素(Concanavalin A)所誘導之周邊血單核細胞增殖作用，且在濃度為1 μg/ml及0.1 μg/ml時即有明顯影響。然而，奈米銀對未受刀豆素刺激之周邊血液單核細胞增殖作用並無顯著影響。細胞激素之mRNA表現量的實驗結果顯示，經四小時處理後，1 μg/ml的奈米銀會暫時性的刺激刀豆素所誘導之白血球介白素4 (Interleukin 4) 的mRNA表現量；在經二十四小時處理之後，1 μg/ml的奈米銀會抑制刀豆素所誘導之白血球介白素2 (Interleukin 2)及白血球介白素12 (Interleukin 12)之mRNA表現量。綜合本研究之發現，奈米銀的暴露可能對瓶鼻海豚造成免疫毒性，在受奈米銀污染的環境中，可能使瓶鼻海豚容易受到特定病原感染或緊迫因子的影響。

Due to the thriving progress in silver nanotechnology, the increasing production and use of silver nanoparticles (AgNPs) would make the marine environment be inevitably contaminated. Cetaceans as the top-level predators with long lifespan of the ocean would have a high potential to be exposed to AgNPs. Hence, the possible adverse effects of AgNPs to the cetaceans should be concerned and studied. The present study evaluated the immunotoxiciy of 20 nm citrate-coated AgNPs (CIT-AgNPs) on the peripheral blood mononuclear cells (PBMCs) of bottlenose dolphins on the cell proliferation and cytokine expression. Blood samples were collected from six bottlenose dolphins captivated in Farglory Ocean Park. The CIT-AgNPs (20 nm) were significantly cytotoxic to PBMCs at 10 μg/ml after 24 and 60 hours of exposure. The CIT-AgNPs at sub-lethal concentration suppressed Concanavalin A (Con A) -induced proliferative activity of PBMCs and exhibited significant inhibitory responses at 0.1 μg/ml and 1 μg/ml. However, no significant effects of AgNPs on lymphocyte proliferation without ConA stimulation were found. The result of cytokine expression demonstrated that the CIT-AgNPs could temporarily increase ConA-induced mRNA expression of IL-4 after 4 hours of incubation at 1 μg/ml. In addition, AgNPs at 1 μg/ml could inhibit ConA-induced mRNA expression of IL-2 and IL-12 after 24 hours of treatment. As above, it is concluded AgNPs has the potential to cause adverse effect on the immune function of cetaceans, which may lead the animals to become more vulnerable to stressors and infections when live in the AgNPs-contaminated environment.