Pozzi Roberta, De Berardis Barbara, Paoletti Luigi, Guastadisegni Cecilia
Dipartimento di Tecnologie e Salute, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
Environ Res. 2005 Nov;99(3):344-54. doi: 10.1016/j.envres.2005.02.004.
Epidemiological data show an association between exposure to elevated levels of particulate matter (PM), in particular the fine fraction (<2.5 microm in diameter), and an increase in cardiovascular mortality and respiratory symptoms. The aim of this study was to compare the in vitro toxicity of coarse and fine particulate matter collected with a cascade impactor during winter in an urban area of Rome in relation to their physicochemical characterization (size distribution and chemical composition) as assessed by analytical electron microscopy (SEM/EDX). The X-ray microanalysis data of single particles of coarse and fine matter were analyzed by hierarchical cluster analysis to determine the principal component of the two granulometric fractions. The main chemical difference between the two fractions was the greater abundance of carbonaceous particles in the fine fraction. We compared the ability of coarse and fine fractions, carbon black (CB), and residual oil fly ash (ROFA) to induce arachidonic acid release and tumor necrosis factor-alpha (TNF-alpha) production in the monocytic-macrophagic RAW 264.7 cell line at concentrations of 30 and 120 microg/mL. Our results showed that CB and ROFA were consistently less effective than both fractions of urban particles at inducing an inflammatory reaction in RAW 264.7 cells. Both PM fractions dose-dependently increased TNF-alpha production in RAW 264.7 cells after 5 and 24h of incubation, and only the TNF-alpha production induced by coarse particles at 30 microg/mL decreased significantly (P<0.01) after 24h of treatment. In our in vitro model the winter fine fraction was more reactive than the winter coarse fraction, in contrast to a previously examined summer sample. In the summer sample, coarse particles produced higher levels of inflammatory mediators than fine particles and the CB was consistently less effective than the urban particles. The different behaviors between summer and winter urban fractions may be due to their different physicochemical characteristics; in fact, the comparison of the two samples' characterization by SEM/EDX and X-ray photoelectron spectroscopy (XPS) analysis showed that in winter the carbonaceous particles are more abundant than in summer and that winter particles carry a greater quantity of organic compounds. We suggest that the higher concentration of organic compounds on fine carbonaceous particles may partially explain the higher activation of RAW 264.7 cells by fine particles.
流行病学数据显示，暴露于高水平的颗粒物（PM），尤其是细颗粒物（直径<2.5微米），与心血管疾病死亡率增加及呼吸道症状增多之间存在关联。本研究的目的是比较在罗马市区冬季用串级冲击器收集的粗颗粒物和细颗粒物的体外毒性，并将其与通过分析电子显微镜（SEM/EDX）评估的物理化学特性（粒径分布和化学成分）相关联。通过层次聚类分析对粗颗粒物和细颗粒物单颗粒的X射线微分析数据进行分析，以确定两个粒度级分的主要成分。两个级分之间的主要化学差异在于细级分中含碳颗粒的丰度更高。我们比较了粗级分和细级分、炭黑（CB）以及残油飞灰（ROFA）在30和120微克/毫升浓度下诱导单核巨噬细胞RAW 264.7细胞系中花生四烯酸释放和肿瘤坏死因子-α（TNF-α）产生的能力。我们的结果表明，在诱导RAW 264.7细胞发生炎症反应方面，CB和ROFA始终不如城市颗粒物的两个级分有效。两种PM级分在孵育5小时和24小时后均能剂量依赖性地增加RAW 264.7细胞中TNF-α的产生，并且仅在处理24小时后，3微米/毫升粗颗粒物诱导的TNF-α产生显著降低（P<0.01）。在我们的体外模型中，与之前检测的夏季样本相比，冬季细级分比冬季粗级分更具反应性。在夏季样本中，粗颗粒物产生的炎症介质水平高于细颗粒物，并且CB始终不如城市颗粒物有效。夏季和冬季城市级分之间的不同行为可能归因于它们不同的物理化学特性；事实上，通过SEM/EDX和X射线光电子能谱（XPS）分析对两个样本特性的比较表明，冬季的含碳颗粒比夏季更丰富，并且冬季颗粒携带的有机化合物数量更多。我们认为，细含碳颗粒上较高浓度的有机化合物可能部分解释了细颗粒物对RAW 264.7细胞的更高激活作用。
