B(a)P induces ovarian granulosa cell apoptosis via TRAF2-NFκB-Caspase1 axis during early pregnancy

Hanting Xu; Fangyuan Chen; Zhihao Liu; Rufei Gao; Junlin He; Fangfang Li; Nanyan Li; Xinyi Mu; Taihang Liu; Yingxiong Wang; Xuemei Chen

doi:10.1016/j.envres.2024.118865

B(a)P induces ovarian granulosa cell apoptosis via TRAF2-NFκB-Caspase1 axis during early pregnancy

Environ Res. 2024 Apr 5;252(Pt 1):118865. doi: 10.1016/j.envres.2024.118865. Online ahead of print.

Authors

Hanting Xu¹, Fangyuan Chen², Zhihao Liu², Rufei Gao², Junlin He², Fangfang Li², Nanyan Li³, Xinyi Mu¹, Taihang Liu¹, Yingxiong Wang⁴, Xuemei Chen⁵

Affiliations

¹ Joint International Research Laboratory of Reproduction & Development, College of Basic Medicine, Chongqing Medical University, Chongqing 400016, PR China.
² Department of Health Toxicology, School of Public Health, Joint International Research Laboratory of Reproduction & Development, Chongqing Medical University, Chongqing 400016, PR China.
³ Joint International Research Laboratory of Reproduction & Development, Chongqing Medical University, Jiulongpo District Center for Disease Control and Prevention, Chongqing, 400039, PR China.
⁴ Joint International Research Laboratory of Reproduction & Development, College of Basic Medicine, Chongqing Medical University, Chongqing 400016, PR China. Electronic address: yxwang@cqmu.edu.cn.
⁵ Department of Health Toxicology, School of Public Health, Joint International Research Laboratory of Reproduction & Development, Chongqing Medical University, Chongqing 400016, PR China. Electronic address: chenxuemei@cqmu.edu.cn.

PMID: 38583661
DOI: 10.1016/j.envres.2024.118865

Abstract

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 H₂O₂ 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.

Keywords: Apoptosis; BPDE; Benzo(a)pyrene; Ovarian granulosa cell; TRAF2.