Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224, Warsaw, Poland.
Center for Environmental Measurement & Modeling, U.S. Environmental Protection Agency, Research Triangle Park, NC, 27711, United States.
Environ Pollut. 2022 May 15;301:119010. doi: 10.1016/j.envpol.2022.119010. Epub 2022 Feb 22.
Nitrophenols (NPs) are hazardous pollutants found in various environmental matrices, including ambient fine particulate matter (PM), agricultural residues, rainwater, wildfires, and industrial wastes. This study showed for the first time the effect of three pure nitrophenols and their mixture on human lung cells to provide basic understanding of the NP influence on cell elements and processes. We identified NPs in ambient PM and secondary organic aerosol (SOA) particles generated from the photooxidation of monocyclic aromatic hydrocarbons in the U.S. EPA smog chamber. We assessed the toxicity of identified NPs and their equimolar mixture in normal bronchial epithelial (BEAS-2B) and alveolar epithelial cancer (A549) lung cell lines. The inhibitory concentration-50 (IC) values were highest and lowest in BEAS-2B cells treated with 2-nitrophenol (2NP) and 4-nitrophenol (4NP), respectively, at 24 h of exposure. The lactate dehydrogenase (LDH) assay showed that 4NP, the most abundant NP we identified in PM, was the most cytotoxic NP examined in both cell lines. The annexin-V/fluorescein isothiocyanate (FITC) analysis showed that the populations of late apoptotic/necrotic BEAS-2B and A549 cells exposed to 3NP, 4NP, and NP equimolar mixture increased between 24 and 48 h. Cellular reactive oxygen species (ROS) buildup led to cellular death post exposure to 3NP, 4NP and the NP mixtures, while 2NP induced the lowest ROS buildup. An increased mitochondrial ROS signal following NP exposure occurred only in BEAS-2B cells. The tetramethylrhodamine, methyl ester, perchlorate (TMRM) assay showed that exposed cells exhibited collapse of the mitochondrial membrane potential. TMRM signals decreased significantly only in BEAS-2B cells, and most strongly with 4NP exposures. Our results suggest that acute atmospheric exposures to NPs may be toxic at high concentrations, but not at ambient PM concentrations. Further chronic studies with NP and NP-containing PM are warranted to assess their contribution to lung pathologies.
硝酚类化合物（NPs）是在各种环境基质中发现的危险污染物，包括环境细颗粒物（PM）、农业残留物、雨水、野火和工业废物。本研究首次展示了三种纯硝酚类化合物及其混合物对人体肺细胞的影响，为了解 NP 对细胞成分和过程的影响提供了基础。我们在美国环保署烟雾箱中，通过单环芳烃的光氧化作用生成的二次有机气溶胶（SOA）颗粒和环境 PM 中鉴定出了 NPs。我们评估了在正常支气管上皮（BEAS-2B）和肺泡上皮癌细胞（A549）中，鉴定出的 NPs 及其等摩尔混合物的毒性。暴露 24 小时后，在 BEAS-2B 细胞中，2-硝酚（2NP）和 4-硝酚（4NP）的抑制浓度-50（IC）值最高和最低。乳酸脱氢酶（LDH）测定表明，我们在 PM 中鉴定出的最丰富的 NP4NP 在两种细胞系中都是最具细胞毒性的 NP。 Annexin-V/荧光素异硫氰酸酯（FITC）分析表明，在 3NP、4NP 和 NP 等摩尔混合物作用下，晚期凋亡/坏死的 BEAS-2B 和 A549 细胞群在 24 至 48 小时之间增加。暴露于 3NP、4NP 和 NP 混合物后，细胞内活性氧（ROS）的积累导致细胞死亡，而 2NP 诱导的 ROS 积累最低。NP 暴露后，只有 BEAS-2B 细胞中线粒体 ROS 信号增加。四甲基罗丹明甲酯，高氯酸盐（TMRM）测定表明，暴露的细胞表现出线粒体膜电位崩溃。只有在 BEAS-2B 细胞中，TMRM 信号明显下降，而 4NP 暴露时下降最为显著。我们的研究结果表明，急性大气暴露于 NPs 在高浓度时可能具有毒性，但在环境 PM 浓度下则不然。需要进一步进行 NP 和含 NP 的 PM 的慢性研究，以评估它们对肺部病变的贡献。
