柴油排放微粒成分對於人類冠狀動脈內皮細胞毒性之研究

Abstract

流行病學研究指出大氣中的懸浮微粒與心臟血管疾病發生、死亡率相關，其中，懸浮微粒對健康影響主要是由粒徑小於2.5微米(PM2.5)的懸浮微粒所造成而非由粒徑為10至2.5微米（PM10-2.5）範圍的懸浮微粒所致，柴油排放微粒為一重要的大氣PM2.5來源。然而，懸浮微粒的特性如粒徑大小、成份對心血管疾病的影響仍有待釐清。為能瞭解柴油排放微粒特性與血管內皮細胞功能、發炎反應之間的關係，本研究使用十階微孔均勻沉積衝擊採樣器(MOUDITM)，採集台北國道客運站中的柴油排放微粒，採集時間從早上8點到下午6點，自2006年9月至2007年4月共採集了23天，使用感應耦合電漿質譜儀(ICP-MS)分析次微米粒徑、超細微粒柴油排放微粒中的金屬成分。人類冠狀動脈內皮細胞以濃度15和30 &micro;g/mL次微米粒徑、超細微粒柴油排放微粒懸浮液處理4小時，並進而將30 &micro;g/mL次微米粒徑、超細微粒柴油排放微粒懸浮液離心，使柴油排放微粒懸浮液分為上清液以及顆粒狀物部分，再將這兩部分分別暴露於人類冠狀動脈內皮細胞4小時，利用酵素免疫分析法分析內皮功能相關指標如一氧化氮(NO)和內皮素1(ET-1)，以及發炎指標白介素6(IL-6)。 結果顯示國道客運中PM10-1、PM1-0.1和PM0.1的質量濃度±標準差(佔PM10組成百分比)分別為29.3±9.6 (49.5%), 23.6±14.6 (39.9%), 和6.2±2.5 (10.5%) μg/m3，並呈現三個波峰狀的分佈，分別在3.2, 0.56, 和 <0.056 &micro;m出現極大值。其中，鋅是在次微米粒徑、超細微粒柴油排放微粒中含量最多的金屬。人類冠狀動脈內皮細胞暴露於次微米粒徑、超細微粒柴油排放微粒，皆造成NO和ET-1的濃度下降，而次微米粒徑柴油排放微粒引起IL-6的濃度上升，但超細微粒柴油排放微粒卻引起IL-6的濃度下降。相較於柴油排放微粒上清液的部分，顆粒狀物的細胞毒性較低。在金屬成分與NO、ET-1和IL-6產生濃度相關性分析中，發現鈷、鉻、銅的金屬含量與ET-1的產生有正相關，鉻、銅、鋅的金屬含量與IL-6的產生有正相關。本研究結果顯示微粒的化學成分為影響內皮細胞功能和發炎反應的重要因子。

Ambient particulate matter has been considered associated with increased cardiovascular diseases. These associations are strongest for fine particles (PM2.5), of which combustion-derived diesel exhaust particles are important components. Particle sizes, chemical compositions are generally considered responsible for their toxic responses. However, the mechanisms of these effects are not well-certified. The purpose of this study is to investigate organic extracts of DEP (OE-DEP), supernatant OE-DEP, and pellet OE-DEP induced cytotoxicity on human coronary artery endothelial cell (HCAEC) at different particle sizes. A ten-stage micro-orifice uniform deposit impactor (MOUDITM) was used to collect DEP within a size range of 10, 5.6, 3.2, 1.8, 1.0, 0.56, 0.32, 0.18, 0.1, 0.056 &micro;m and <0.056 &micro;m from the platform of an intercity bus station, in Taipei, Taiwan. DEP was collected between 08:00 a.m. and 06:00 p.m. A total of 23 samples were taken between September 2006 and April 2007. Metal contents of submicron/ultrafine fraction OE-DEP were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS). OE-DEP-induced endothelial dysfunctions and inflammatory effects were evaluated by nitrite oxide (NO), endothelin-1 (ET-1), and interleukin-6 (IL-6). All statistical analyses are undertaken by SAS software. The mass concentrations of DEP exhibited a trimodal size distribution peaking at 3.2, 0.56, and <0.056 &micro;m, respectively, in our samples. The mean concentrations with standard deviations (percentage of PM10) of coarse fraction (PM10-1), submicrometer fraction (PM1-0.1), and ultrafine fraction (PM0.1) were 29.3±9.6 (49.5%), 23.6±14.6 (39.9%), and 6.2±2.5 (10.5%) μg/m3, respectively. Zn was both the most abundant element in submicrometer and ultrafine OE-DEP. HCAEC exposed to 30μg/mL OE-DEP for 4h affected endothelial function by decreasing NO concentration in culture and suppressing ET-1 production. OE-DEP stimulated IL-6 production in submicrometer fraction but suppressed IL-6 production in ultrafine fraction. After the removal of supernatant OE-DEP, pellet OE-DEP was showed to be less cytotoxic on HCAEC. Cr, Cu, and Zn were found to induce IL-6 production. Co, Cr, and Cu were found to be associated with ET-1 secretion. Those results suggest that the chemical composition is more potent than particle size on determining endothelial dysfunctions and inflammatory effects.