Document Type

Article

Publication Date

6-5-2026

Identifier

DOI: 10.1093/toxsci/kfag060; PMCID: PMC13242702

Abstract

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental pollutants associated with placenta-mediated pregnancy complications, including preeclampsia, fetal growth restriction, and preterm birth. The syncytiotrophoblast (STB), which forms the placental barrier at the maternal-fetal interface and is directly exposed to maternal blood, is a primary site of PFAS exposure. Although PFAS induce STB apoptosis, the upstream stress-signaling pathways involved remain poorly defined. Here, we investigated stress-responsive signaling mechanisms mediating PFAS-induced STB cell death. STB differentiated from human trophoblast stem cells were exposed to vehicle or an environmentally relevant mixture of 5 PFAS (perfluorooctanoic acid, perfluorooctanesulfonic acid, perfluorohexane sulfonate, perfluorononanoic acid, and perfluorodecanoic acid; 0.0138 to 34.5 µM) for 3 or 6 h. Cytotoxicity, apoptosis, mitochondrial membrane potential, and stress-signaling pathway activation were assessed by lactate dehydrogenase release, immunoblotting, JC-10 assay, and reverse transcription-quantitative PCR. PFAS mixtures did not induce cytotoxicity at 3 h but significantly increased cytotoxicity at 6 h at 34.5 µM, coinciding with the induction of cleaved caspase-3, cleaved poly(ADP-ribose) polymerase, and NOXA. The pan-caspase inhibitor z-VAD-FMK prevented cytotoxicity, indicating caspase-dependent apoptosis. PFAS exposure reduced mitochondrial membrane potential and activated the integrated stress response (ISR), as evidenced by eukaryotic initiation factor 2α phosphorylation, activating transcription factor 4 (ATF4) induction, and increased ATF4 target gene expression. In parallel, c-Jun N-terminal kinase (JNK) signaling was activated, as evidenced by JNK phosphorylation and induction of immediate-early genes (JUN, FOS, EGR1). Pharmacologic inhibition of the ISR modestly attenuated PFAS-induced cytotoxicity, whereas pharmacologic inhibition of JNK rescued cytotoxicity and apoptotic signaling. Together, these findings identify JNK-driven stress signaling as the dominant mediator of PFAS-induced STB apoptosis, with a secondary contribution from the ISR.

Journal Title

Toxicological sciences : an official journal of the Society of Toxicology

Volume

209

Issue

6

PubMed ID

42172632

Keywords

JNK signaling; PFAS mixtures; apoptosis; placenta; syncytiotrophoblast

Comments

Grants and funding

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.

Publisher's Link: https://academic.oup.com/toxsci/article/209/6/kfag060/8690978

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