Joint International Research Laboratory of Reproduction & Development, College of Basic Medicine, Chongqing Medical University, Chongqing 400016, PR China.
Department of Health Toxicology, School of Public Health, Joint International Research Laboratory of Reproduction & Development, Chongqing Medical University, Chongqing 400016, PR China.
Environ Res. 2024 Jul 1;252(Pt 1):118865. doi: 10.1016/j.envres.2024.118865. Epub 2024 Apr 5.
Benzo(a)pyrene [B(a)P] is an environmental endocrine disruptor with reproductive toxicity. The corpus luteum (CL) of the ovary plays an important role in embryo implantation and pregnancy maintenance. Our previous studies have shown that B(a)P exposure affects embryo implantation and endometrial decidualization in mouse, but its effects and mechanisms on CL function remain unclear. In this study, we explore the mechanism of ovarian toxicity of B(a)P using a pregnant mouse model and an in vitro model of human ovarian granulosa cells (GCs) KGN. Pregnant mice were gavaged with corn oil or 0.2 mg/kg.bw B(a)P from pregnant day 1 (D1) to D7, while KGN cells were treated with DMSO, 1.0IU/mL hCG, or 1.0IU/mL hCG plus benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE), a B(a)P metabolite. Our findings revealed that B(a)P exposure damaged embryo implantation and reduced estrogen and progesterone levels in early pregnant mice. Additionally, in vitro, BPDE impaired luteinization in KGN cells. We observed that B(a)P/BPDE promoted oxidative stress (OS) and inflammation, leading to apoptosis rather than pyroptosis in ovaries and luteinized KGN cells. This apoptotic response was mediated by the activation of inflammatory Caspase1 through the cleavage of BID. Furthermore, B(a)P/BPDE inhibited TRAF2 expression and suppressed NFκB signaling pathway activation. The administration of VX-765 to inhibit the Caspase1 activation, over-expression of TRAF2 using TRAF2-pcDNA3.1 (+) plasmid, and BetA-induced activation of NFκB signaling pathway successfully alleviated BPDE-induced apoptosis and cellular dysfunction in luteinized KGN cells. These findings were further confirmed in the KGN cell treated with HO and NAC. In conclusion, this study elucidated that B(a)P/BPDE induces apoptosis rather than pyroptosis in GCs via TRAF2-NFκB-Caspase1 during early pregnancy, and highlighting OS as the primary contributor to B(a)P/BPDE-induced ovarian toxicity. Our results unveil a novel role of TRAF2-NFκB-Caspase1 in B(a)P-induced apoptosis and broaden the understanding of mechanisms underlying unexplained luteal phase deficiency.
苯并[a]芘 [B(a)P] 是一种具有生殖毒性的环境内分泌干扰物。卵巢黄体（CL）在胚胎着床和妊娠维持中起着重要作用。我们之前的研究表明，B(a)P 暴露会影响小鼠的胚胎着床和子宫内膜蜕膜化，但它对 CL 功能的影响和机制尚不清楚。在这项研究中，我们使用怀孕小鼠模型和人卵巢颗粒细胞（GCs）KGN 的体外模型探索了 B(a)P 的卵巢毒性机制。从怀孕第 1 天（D1）到 D7，给怀孕小鼠灌胃玉米油或 0.2mg/kg.bw B(a)P，而 KGN 细胞用 DMSO、1.0IU/mL hCG 或 1.0IU/mL hCG 加苯并[a]芘-7,8-二氢二醇-9,10-环氧化物（BPDE），B(a)P 代谢物处理。我们的研究结果表明，B(a)P 暴露会损害胚胎着床，并降低早孕小鼠的雌激素和孕激素水平。此外，体外实验表明，BPDE 会损害 KGN 细胞的黄体化。我们观察到，B(a)P/BPDE 促进氧化应激（OS）和炎症，导致卵巢和黄体化 KGN 细胞发生凋亡而不是焦亡。这种凋亡反应是通过 BID 的切割激活炎性 Caspase1 介导的。此外，B(a)P/BPDE 抑制 TRAF2 的表达，并抑制 NFκB 信号通路的激活。用 VX-765 抑制 Caspase1 激活、用 TRAF2-pcDNA3.1(+)质粒过表达 TRAF2 以及用 BetA 诱导 NFκB 信号通路激活成功缓解了 BPDE 诱导的黄体化 KGN 细胞凋亡和细胞功能障碍。这些发现进一步在用 HO 和 NAC 处理的 KGN 细胞中得到证实。总之，本研究表明，在早孕期间，B(a)P/BPDE 通过 TRAF2-NFκB-Caspase1 诱导 GCs 发生凋亡而不是焦亡，并且强调 OS 是 B(a)P/BPDE 诱导卵巢毒性的主要原因。我们的结果揭示了 TRAF2-NFκB-Caspase1 在 B(a)P 诱导凋亡中的新作用，并拓宽了对不明原因黄体期缺陷机制的理解。
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