Department of Forensic Medicine, Nagoya City University Graduate School of Medical Sciences 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, 467-8601, Japan.
Center for Health and Environmental Risk Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki, 305-8506, Japan.
Chem Biol Interact. 2020 Feb 1;317:108962. doi: 10.1016/j.cbi.2020.108962. Epub 2020 Jan 24.
Quaternary ammonium compounds (e.g., benzalkonium chloride (BAC) and cetylpyridinium chloride (CPC)) constitute a group of cationic surfactants are widely used for personal hygiene and medical care despite the potential pulmonary toxicity. To examine whether BAC and CPC aerosols deposited in the alveolar region alter pulmonary function, we studied the effects on pulmonary surfactant using two-step in vitro models; cytotoxicity using A549 alveolar epithelial cell and changes in surface activity of the pulmonary surfactant monolayer using both Surfacten® and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). Cell viability was decreased with BAC and CPC dose-dependently. A comparison of cytotoxicity among BAC homologues with different length of alkyl chain showed that C-BAC, which has the longest alkyl chain, was more cytotoxic than C- or C-BAC. Caspase-3/7 activity and cleaved form of caspase-3 and PARP were increased in BAC- and CPC-exposed cells. The elevated caspase-3/7 activity and their cleaved active forms were abolished by caspase-3-inhibitor. Furthermore, we examined the features of the surface pressure/trough area (π-A) isotherm by the Langmuir-Wilhelmy method and atomic force microscopy (AFM) images of lipid monolayers on a subphase containing BAC, CPC, or pyridinium chloride (PC, as a control). The π-A isotherms showed that addition of BAC or CPC yielded dose-dependent increases in surface pressure without compression, indicating that BAC and CPC expand the isotherm to larger areas at lower pressure. The collapse pressure diminished with increasing concentration of CPC. Topographic images indicated that BAC and CPC resulted in smaller condensed lipid domains compared to the control. Conversely, PC without hydrocarbon tail group, showed no cytotoxicity and did not change the isotherms and AFM images. These results indicate that BAC and CPC cause cell death via caspase-3-dependent apoptotic pathway in A549 cells and alter the alveolar surfactant activity. These effects can be attributed to the long alkyl chain of BAC and CPC.
季铵化合物（例如苯扎氯铵（BAC）和十六烷基氯化吡啶（CPC））属于阳离子表面活性剂的一类，广泛应用于个人卫生和医疗保健领域，尽管其具有潜在的肺毒性。为了研究肺泡区域中 BAC 和 CPC 气溶胶的沉积是否会改变肺功能，我们使用两步体外模型研究了其对肺表面活性剂的影响；使用 A549 肺泡上皮细胞进行细胞毒性研究，使用 Surfacten®和 1,2-二棕榈酰基-sn-甘油-3-磷酸胆碱（DPPC）研究肺表面活性剂单层的表面活性变化。细胞活力随 BAC 和 CPC 剂量依赖性降低。不同链长的 BAC 同系物的细胞毒性比较表明，具有最长烷基链的 C-BAC 比 C-或 C-BAC 更具细胞毒性。暴露于 BAC 和 CPC 的细胞中 caspase-3/7 活性以及 caspase-3 和 PARP 的裂解形式增加。Caspase-3 抑制剂可消除 caspase-3/7 活性及其裂解的活性形式。此外，我们通过 Langmuir-Wilhelmy 方法和原子力显微镜（AFM）检查了表面压力/低谷面积（π-A）等温线的特征，以及含有 BAC、CPC 或吡啶氯化物（PC，作为对照）的亚相上的脂质单层的 AFM 图像。π-A 等温线表明，添加 BAC 或 CPC 会导致表面压力随剂量增加而增加，而无需压缩，这表明 BAC 和 CPC 在较低压力下将等温线扩展到更大的区域。随着 CPC 浓度的增加，崩溃压力降低。形貌图像表明，与对照相比，BAC 和 CPC 导致较小的凝聚脂质域。相反，没有烃尾基团的 PC 既没有细胞毒性，也没有改变等温线和 AFM 图像。这些结果表明，BAC 和 CPC 通过 caspase-3 依赖性凋亡途径导致 A549 细胞死亡，并改变肺泡表面活性剂活性。这些影响可归因于 BAC 和 CPC 的长烷基链。
