大氣懸浮微粒粒徑對小鼠之呼吸毒理研究

Abstract

近年來空氣汙染造成的健康效應備受矚目。大氣懸浮微粒是空氣汙染中主要的汙染物，也被視為造成健康危害的元凶之一。過去大氣懸浮微粒健康效應之研究已有大量文獻，然而目前的研究對於細小粒徑之微粒(PM1、PM0.1)仍有待探討，尤其目前對於不同粒徑微粒之呼吸毒性及微粒造成過敏性免疫反應的相關研究仍有所缺乏，故本研究比較不同粒徑間以及微粒上成份造成之毒性進行探討。 本研究將蒐集於濾紙上之大氣懸浮微粒配製成懸浮溶液，以氣管灌注暴露方式，使健康小鼠暴露於大氣懸浮微粒，實驗分成五大組，分別為控制組、暴露超細懸浮微粒、暴露次微米懸浮微粒、暴露細懸浮微粒、暴露粗懸浮微粒並且依粒徑之不同分別暴露三種不同劑量之大氣懸浮微粒(1.75 mg/kg、5 mg/kg、12.5 mg/kg)。本研究於第二次暴露後進行連續二十四小時尿液採集，並且於四十八小時後進行呼吸道阻力測試，於七十二小時後進行動物犧牲。犧牲時進行血液樣本與肺泡灌洗液採集，並進行細胞計數、生化指標之分析。 本研究所採集之微粒特性，在粒徑較大者(PM1、PM2.5及PM10)其組成成分以硫酸根離子為主其餘為銨根離子與無機金屬離子。在最小微粒者(PM0.1)以有機碳與元素碳為主。於肺部發炎反應部分，微粒暴露後會造成肺泡灌洗液中嗜中性球、淋巴球之數量上升以及肺部發炎指標包含Th1 細胞相關激素TNF-α, IFN-γ及IL-6與總蛋白質含量及Th17之細胞激素IL-17A 之上升，過敏性免疫反應部份，指標包含嗜酸白血球，第二型輔助T細胞相關激素IL-5, IL-10及IL-13具有明顯上升，以整體趨勢而言皆以大粒徑之粗懸浮微粒(PM10)反應最為顯著。以成分而言，細菌內毒素以及海鹽相關離子Na+、Mg2+、Ca2+、Cl-與發炎反應、過敏性免疫反應具有高度相關性。 本研究提供不同粒徑微粒與微粒成分在呼吸毒理上的相關探討，並且對於未來在超細粒徑懸浮微粒毒理議題上提供相關資料。但毒性相關的微粒成份及微粒來源仍須後續深入研究。

Evidence suggests that particulate matter (PM) is associated with cardiopulmonary effect and exacerbation of asthma. However, it is unclear whether repeated exposure to PM would cause inflammatory and immunological effects. The aim of this study is to evaluate the effects of size-fractioned PM on lung inflammation and immune responses in healthy BALB/c mice. We collected PM10, PM2.5, PM1 and PM0.1 from October 2012 to August 2013 at Gongguan, Taipei. These particles represented urban traffic pollution. Samples were extracted and sonicated with phosphate-buffered saline (PBS). Female BALB/c mice exposed to PM10, PM2.5, PM1, PM0.1 and PBS via intratracheal instillation with three doses of 1.75 mg/kg (35μg/per mice), 5mg/kg (100 μg/per mice), 12.5mg/kg (250 μg/per mice). After exposures, cellular profile of plasma and expression of inflammation biomarkers, immune cytokines in bronchoalveolar lavage fluid (BALF), and pulmonary responses were assessed. PM increased inflammatory responses including neutrophils, T helper 1 cell related cytokines, TNF-α, IFN-γ. Allergic immune responses including eosinophils, T helper 2 cell related cytokines, IL-5, IL-10, IL-13, IL-17A were also increased in BALF. These inflammatory and allergic immune markers were greater in PM10 high dose group.We also found that endotoxin, Na+, Mg2+, Ca2+ and Cl- were correlated with pulmonary inflammation and immune response. Our results indicated that exposure to particulate matter would cause allergy-like immune responses in healthy mice. However the components of PM suspension for these immune responses needs further study.