Department of Environmental Health Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109-2029, USA.
Department of Environmental Health Sciences, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109-2029, USA.
Toxicol Appl Pharmacol. 2014 Jan 15;274(2):283-92. doi: 10.1016/j.taap.2013.11.015. Epub 2013 Dec 1.
Polybrominated diphenyl ethers (PBDEs) are widely used flame retardant compounds. Brominated diphenyl ether (BDE)-47 is one of the most prevalent PBDE congeners found in human breast milk, serum and placenta. Despite the presence of PBDEs in human placenta, effects of PBDEs on placental cell function are poorly understood. The present study investigated BDE-47-induced reactive oxygen species (ROS) formation and its role in BDE-47-stimulated proinflammatory cytokine release in a first trimester human extravillous trophoblast cell line, HTR-8/SVneo. Exposure of HTR-8/SVneo cells for 4h to 20μM BDE-47 increased ROS generation 1.7 fold as measured by the dichlorofluorescein (DCF) assay. Likewise, superoxide anion production increased approximately 5 fold at 10 and 15μM and 9 fold at 20μM BDE-47 with a 1-h exposure, as measured by cytochrome c reduction. BDE-47 (10, 15 and 20μM) decreased the mitochondrial membrane potential by 47-64.5% at 4, 8 and 24h as assessed with the fluorescent probe Rh123. Treatment with 15 and 20μM BDE-47 stimulated cellular release and mRNA expression of IL-6 and IL-8 after 12 and 24-h exposures: the greatest increases were a 35-fold increased mRNA expression at 12h and a 12-fold increased protein concentration at 24h for IL-6. Antioxidant treatments (deferoxamine mesylate, (±)α-tocopherol, or tempol) suppressed BDE-47-stimulated IL-6 release by 54.1%, 56.3% and 37.7%, respectively, implicating a role for ROS in the regulation of inflammatory pathways in HTR-8/SVneo cells. Solvent (DMSO) controls exhibited statistically significantly decreased responses compared with non-treated controls for IL-6 release and IL-8 mRNA expression, but these responses were not consistent across experiments and times. Nonetheless, it is possible that DMSO (used to dissolve BDE-47) may have attenuated the stimulatory actions of BDE-47 on cytokine responses. Because abnormal activation of proinflammatory responses can disrupt trophoblast functions necessary for placental development and successful pregnancy, further investigation is warranted of the impact of ROS and BDE-47 on trophoblast cytokine responses.
多溴联苯醚（PBDEs）是广泛使用的阻燃化合物。溴代二苯醚（BDE）-47 是在人乳、血清和胎盘发现的最普遍的 PBDE 同系物之一。尽管人胎盘中有 PBDE 存在，但 PBDE 对胎盘细胞功能的影响知之甚少。本研究调查了 BDE-47 诱导的活性氧（ROS）形成及其在 BDE-47 刺激人早孕绒毛外滋养层细胞系 HTR-8/SVneo 中促炎细胞因子释放中的作用。HTR-8/SVneo 细胞暴露于 20μM BDE-47 4 小时，通过二氯荧光素（DCF）测定法 ROS 生成增加 1.7 倍。同样，在 10μM 和 15μM 时超氧阴离子的产生增加了约 5 倍，在 20μM BDE-47 时增加了 9 倍，在 1 小时暴露时用细胞色素 c 还原法测定。BDE-47（10、15 和 20μM）在 4、8 和 24 小时时使线粒体膜电位降低 47-64.5%，用荧光探针 Rh123 评估。用 15μM 和 20μM BDE-47 处理 12 和 24 小时后，刺激细胞释放和 IL-6 和 IL-8 的 mRNA 表达：最大增加为 12 小时时 35 倍的 mRNA 表达和 24 小时时 12 倍的蛋白质浓度。抗氧化剂处理（甲磺酸去铁胺、（±）α-生育酚或 tempol）抑制 BDE-47 刺激的 IL-6 释放分别为 54.1%、56.3%和 37.7%，表明 ROS 在调节 HTR-8/SVneo 细胞中炎症途径中起作用。溶剂（DMSO）对照与未经处理的对照相比，IL-6 释放和 IL-8 mRNA 表达的反应显著降低，但这些反应在不同实验和时间不一致。尽管如此，DMSO（用于溶解 BDE-47）可能减弱了 BDE-47 对细胞因子反应的刺激作用。由于异常激活促炎反应会破坏胎盘发育和成功妊娠所必需的滋养层功能，因此需要进一步研究 ROS 和 BDE-47 对滋养层细胞因子反应的影响。
