Perfluoroalkyl and polyfluoroalkyl substances (PFASs) and organophosphate flame retardants (OPFRs) are chemicals that may contribute to placenta-mediated complications and adverse maternal-fetal health risks. Few studies have investigated these chemicals in relation to biomarkers of effect during pregnancy. We measured 12 PFASs and four urinary OPFR metabolites in 132 healthy pregnant women during mid-gestation and examined a subset with biomarkers of placental development and disease (n = 62). Molecular biomarkers included integrin alpha-1 (ITGA1), vascular endothelial-cadherin (CDH5), and matrix metalloproteinase-1 (MMP1). Morphological endpoints included potential indicators of placental stress and the extent of cytotrophoblast (CTB)-mediated uterine artery remodeling. Serum PFASs and urinary OPFR metabolites were detected in ∼50–100% of samples. The most prevalent PFASs were perfluorononanoic acid (PFNA), perfluorooctanoic acid (PFOA), and perfluorooctane sulfonic acid (PFOS), with geometric mean (GM) levels of ∼1.3–2.8 (95% confidence limits from 1.2–3.1) ng/mL compared to ≤ 0.5 ng/mL for other PFASs. Diphenyl phosphate (DPhP) and bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) were the most prevalent OPFR metabolites, with GMs of 2.9 (95% CI: 2.5–3.4) and 3.6 (95% CI: 2.2–3.1) ng/mL, respectively, compared to < 1 ng/mL for bis(2-chloroethyl) phosphate (BCEP) and bis(1-chloro-2-propyl) phosphate (BCIPP). We found inverse associations of PFASs or OPFRs with ITGA1 or CDH5 immunoreactivity and positive associations with indicators of placental stress in multiple basal plate regions, indicating these chemicals may contribute to abnormal placentation and future health risks. Associations with blood pressure and lipid concentrations warrant further examination. This is the first study of these chemicals with placental biomarkers measured directly in human tissues and suggests specific biomarkers are sensitive indicators of exposure during a vulnerable developmental period.

Background: Polybrominated diphenyl ether (PBDE) exposures have been associated with adverse pregnancy outcomes. A hypothesized mechanism is via alterations in placental development and function. However, we lack biomarkers that can be used as early indicators of maternal/fetal response to PBDE exposures and/or perturbations in placental development or function. Methods: To evaluate the relationship between PBDE levels and placental biomarkers during mid-gestation of human pregnancy (n = 62), we immunolocalized three molecules that play key roles in cytotrophoblast (CTB) differentiation and interstitial/endovascular uterine invasion-integrin alpha-1 (ITGA1), vascular endothelial-cadherin (CDH5), and metalloproteinase-1 (MMP1)-and assessed three morphological parameters as potential indicators of pathological alterations using H&E-stained tissues-leukocyte infiltration, fibrinoid deposition, and CTB endovascular invasion. We evaluated associations between placental PBDE levels and of biomarkers of placental development and disease using censored Kendall's tau correlation and linear regression methods. Results: PBDEs were detected in all placental samples. We observed substantial variation in antigen expression and morphological endpoints across placental regions. We observed an association between PBDE concentrations and immunoreactivity of endovascular CTB staining with anti-ITGA1 (inverse) or interstitial CTBs staining with anti-CDH5 (positive).

During human pregnancy, cytotrophoblasts (CTBs) from the placenta differentiate into specialized subpopulations that play critical roles in proper fetal growth and development. A subset of these CTBs differentiate along an invasive pathway, penetrating the decidua and anchoring the placenta to the uterus. A critical hurdle in pregnancy is the ability of these cells to migrate, invade, and remodel spiral arteries, ensuring adequate blood flow to nourish the developing fetus. While advances continue in describing the molecular features regulating the differentiation of these cells, assessment of their global proteomic changes at midgestation remain undefined. Here, using sequential window acquisition of all theoretical fragment-ion spectra (SWATH), a data-independent acquisition strategy, we characterized the protein repertoire of second trimester human CTBs during their differentiation towards an invasive phenotype. This mass spectrometry-based approach allowed identification of 3,026 proteins across four culture time points corresponding to sequential stages of differentiation, confirming the expression dynamics of established molecules and offering new information into other pathways involved. The availability of a SWATH CTB global spectral library serves as a beneficial resource for hypothesis generation and a foundation for further understanding of CTB differentiation dynamics.