data_sheet_1_Neutrophil Depletion Exacerbates Pregnancy Complications, Including Placental Damage, Induced by Silica Nanoparticles in Mice.PDF

Recent advances in nanotechnology have led to the development of nanoparticles with innovative functions in various fields. However, the biological effects of nanoparticles—particularly those on the fetus—need to be investigated in detail, because several previous studies have shown that various nanoparticles induce pregnancy complications in mice. In this regard, our previous findings in mice suggested that the increase in peripheral neutrophil count induced by treatment with silica nanoparticles with a diameter of 70 nm (nSP70) may play a role in the associated pregnancy complications. Therefore, here, we sought to define the role of neutrophils in nSP70-induced pregnancy complications. The peripheral neutrophil count in pregnant BALB/c mice at 24 h after treatment with nSP70 was significantly higher than in saline-treated mice. In addition, maternal body weight, uterine weight, and the number of fetuses in nSP70-treated mice pretreated with anti-antibodies, which deplete neutrophils, were significantly lower than those in nSP70-treated mice pretreated with phosphate-buffered saline or isotype-matched control antibodies. Histology revealed that neutrophil depletion increased nSP70-induced placental damage from the decidua through the spongiotrophoblast layer and narrowed spiral arteries in the placentae. In addition, depletion of neutrophils augmented nSP70-induced cytotoxicity to fetal vessels, which were covered with endothelium. The rate of apoptotic cell death was significantly higher in the placentae of anti-nSP70-treated mice than in those from mice pretreated with isotype-matched control antibodies. Therefore, impairment of placental vessels and apoptotic cell death due to nSP70 exposure is exacerbated in the placentae of nSP70-treated mice pretreated with anti-antibodies. Depletion of neutrophils worsens nSP70-induced pregnancy complications in mice; this exacerbation was due to enhanced impairment of placental vessels and increased apoptotic cell death in maternal placentae. Our results provide basic information regarding the mechanism underlying silica-nanoparticle-induced pregnancy complications.

纳米技术的近期进展催生了在多领域具备创新功能的纳米颗粒的开发与应用。然而，纳米颗粒的生物学效应——尤其是其对胎儿的影响——仍有待深入研究，因既往多项研究已证实，多种纳米颗粒可诱发小鼠发生妊娠并发症。有鉴于此，我们团队此前在小鼠模型中的研究结果显示，经直径70nm二氧化硅纳米颗粒(silica nanoparticles)处理后，外周血中性粒细胞(neutrophil)计数升高，可能与相关妊娠并发症的发生存在关联。因此，本研究旨在明确中性粒细胞在nSP70诱发的妊娠并发症中所发挥的作用。经nSP70处理24小时后，妊娠BALB/c小鼠的外周血中性粒细胞计数显著高于生理盐水处理组小鼠。此外，预先使用可耗竭中性粒细胞的抗体处理的nSP70给药小鼠，其母体体重、子宫重量以及胎鼠数量均显著低于预先使用磷酸盐缓冲液(phosphate-buffered saline, PBS)或同型对照抗体(isotype-matched control antibodies)处理的nSP70给药小鼠。组织学分析显示，中性粒细胞耗竭可加重nSP70诱导的胎盘损伤，损伤范围从蜕膜(decidua)层延伸至海绵滋养层(spongiotrophoblast layer)，并使胎盘内的螺旋动脉(spiral arteries)狭窄。此外，中性粒细胞耗竭会增强nSP70对被内皮细胞覆盖的胎鼠血管的细胞毒性作用。预先使用可耗竭中性粒细胞的抗体处理的nSP70给药小鼠的胎盘组织中，细胞凋亡(apoptotic cell death)率显著高于预先使用同型对照抗体处理的小鼠。因此，在预先使用可耗竭中性粒细胞的抗体处理的nSP70给药小鼠的胎盘组织中，nSP70暴露所致的胎盘血管损伤与细胞凋亡均进一步加重。中性粒细胞耗竭会加重小鼠nSP70诱导的妊娠并发症，该加重效应源于母体胎盘内胎盘血管损伤的加剧与细胞凋亡率的升高。本研究结果为阐明二氧化硅纳米颗粒诱发妊娠并发症的潜在机制提供了基础数据。