Hallberg Ida, Persson Sara, Olovsson Matts, Sirard Marc-André, Damdimopoulou Pauliina, Rüegg Joëlle, Sjunnesson Ylva C B
Department of Clinical Sciences, Division of Reproduction, The Centre for Reproductive Biology in Uppsala, Swedish University of Agricultural Sciences, SE-750 07, Uppsala, Sweden.
Department of Clinical Sciences, Division of Reproduction, The Centre for Reproductive Biology in Uppsala, Swedish University of Agricultural Sciences, SE-750 07, Uppsala, Sweden.
Toxicology. 2021 Dec;464:153028. doi: 10.1016/j.tox.2021.153028. Epub 2021 Nov 8.
Perfluorooctane sulfonate (PFOS) has been added to Stockholm Convention for global phase out, but will continue to contribute to the chemical burden in humans for a long time to come due to extreme persistence in the environment. In the body, PFOS is transferred into to the ovarian follicular fluid that surrounds the maturing oocyte. In the present study, bovine cumulus oocyte complexes were exposed to PFOS during 22 h in vitro maturation. Concentrations of 2 ng g (PFOS-02) representing average human exposure and 53 ng g (PFOS-53) relevant to highly exposed groups were used. After exposure, developmental competence was recorded until day 8 after fertilisation. Blastocysts were fixed and either stained to evaluate blastomere number and lipid distribution using confocal microscopy or frozen and pooled for microarray-based gene expression and DNA methylation analyses. PFOS-53 delayed the first cleavage to two-cell stage and beyond at 44 h after fertilisation (p < .01). No reduction of proportion blastocysts were seen at day 8 in either of the groups, but PFOS-53 exposure resulted in delayed development into more advanced stages of blastocysts seen as both reduced developmental stage (p = .001) and reduced number of blastomeres (p = .04). Blastocysts showed an altered lipid distribution that was more pronounced after exposure to PFOS-53 (increased total lipid volume, p=.0003, lipid volume/cell p < .0001) than PFOS-02, where only decreased average lipid droplet size (p=.02) was observed. Gene expression analyses revealed pathways differently regulated in the PFOS-treated groups compared to the controls, which were related to cell death and survival through e.g., P38 mitogen-activated protein kinases and signal transducer and activator of transcription 3, which in turn activates tumour protein 53 (TP53). Transcriptomic changes were also associated with metabolic stress response, differentiation and proliferation, which could help to explain the phenotypic changes seen in the blastocysts. The gene expression changes were more pronounced after exposure to PFOS-53 compared to PFOS-02. DNA-methylation changes were associated with similar biological functions as the transcriptomic data, with the most significantly associated pathway being TP53. Collectively, these results reveal that brief PFOS exposure during oocyte maturation alters the early embryo development at concentrations relevant to humans. This study adds to the evidence that PFOS has the potential to affect female fertility.
全氟辛烷磺酸（PFOS）已被列入《斯德哥尔摩公约》以进行全球淘汰，但由于其在环境中具有极强的持久性，在未来很长一段时间内仍将继续增加人类的化学负担。在体内，PFOS会转移到围绕成熟卵母细胞的卵泡液中。在本研究中，牛卵丘-卵母细胞复合体在体外成熟22小时期间暴露于PFOS。使用代表人类平均暴露水平的2 ng/g（PFOS-02）和与高暴露组相关的53 ng/g（PFOS-53）的浓度。暴露后，记录发育能力直至受精后第8天。将囊胚固定，要么进行染色以使用共聚焦显微镜评估卵裂球数量和脂质分布，要么冷冻并合并用于基于微阵列的基因表达和DNA甲基化分析。PFOS-53在受精后44小时延迟了第一次分裂至二细胞期及以后（p < 0.01）。在第8天，两组中均未观察到囊胚比例降低，但PFOS-53暴露导致发育延迟至更高级阶段的囊胚，表现为发育阶段降低（p = 0.001）和卵裂球数量减少（p = 0.04）。囊胚显示出脂质分布改变，与PFOS-02相比，暴露于PFOS-53后更为明显（总脂质体积增加，p = 0.0003，脂质体积/细胞p < 0.0001），而PFOS-02仅观察到平均脂滴大小减小（p = 0.02）。基因表达分析显示，与对照组相比，PFOS处理组中存在不同调节的途径，这些途径与细胞死亡和存活相关，例如通过P38丝裂原活化蛋白激酶以及信号转导和转录激活因子3，进而激活肿瘤蛋白53（TP53）。转录组变化还与代谢应激反应、分化和增殖相关，这有助于解释在囊胚中观察到的表型变化。与PFOS-02相比，暴露于PFOS-53后基因表达变化更为明显。DNA甲基化变化与转录组数据具有相似的生物学功能，最显著相关的途径是TP53。总体而言，这些结果表明，卵母细胞成熟期间短暂暴露于PFOS会在与人类相关浓度下改变早期胚胎发育。本研究进一步证明了PFOS有可能影响女性生育能力。
