Inflammation-mediated generation and inflammatory potential of human placental cell-free fetal DNA. (April 2020)

• Record Type: Journal Article
• Authors: van Boeckel, Sara R.; Macpherson, Heather; Norman, Jane E.; Davidson, Donald J.; Stock, Sarah J.
• Is Part Of: Placenta. Volume 93(2020)
• Page Start: 49
• Page End: 55
• Publication Date: 2020-04
• Subjects: Cell-free fetal DNA -- Placental inflammation -- Pre-eclampsia -- Preterm birth -- Pathogenesis -- DNA methylation -- Toll-like receptor 9; Placenta -- Periodicals; Reproduction -- Periodicals; Placenta -- Periodicals; Placenta -- Périodiques; Reproduction -- Périodiques; 612.63
• DOI: 10.1016/j.placenta.2020.02.016
• Languages: English
• ISSNs: 0143-4004

Abstract

Abstract: Introduction: Circulating DNA can be pro-inflammatory when detected by leukocytes via toll-like receptor 9 (TLR9). Cell-free fetal DNA (cff-DNA) of placental origin, circulates in pregnancy, and increased concentrations are seen in conditions associated with placental and maternal inflammation such as pre-eclampsia. However, whether cff-DNA is directly pro-inflammatory in pregnant women and what regulates cff-DNA levels in pregnancy are unknown. Methods: Using a human term placental explant model, we examined whether induction of placental inflammation can promote cff-DNA release, and the capacity of this cff-DNA to stimulate peripheral blood mononuclear cells (PBMCs) from pregnant women. Results: We demonstrate lipopolysaccharide (LPS)-mediated inflammation in placental explants and induced apoptosis after 24 h. However, this did not increase levels of cff-DNA generation compared to controls. Furthermore, the methylation status of the cff-DNA, was not altered by LPS-induced inflammation. Cff-DNA did not elicit production of inflammatory cytokines from PBMCs, in contrast to exposure to LPS or the TLR9 agonist CpG-ODN. Finally, we demonstrate that cff-DNA acquired directly from pregnant women did not differ in methylation status from placental extracted DNA, or from placental explant generated cell-free DNA, and that, unlike Escherichia coli DNA, this cff-DNA has a low level of unmethylated CpG sequences. Discussion: Our data suggest that placental inflammation does not increase release of cff-DNA and that placental cff-DNA is not pro-inflammatory to circulating PBMCs. It thus seems unlikely that high levels of cff-DNA are either a direct consequence or cause of inflammation observed in obstetric complications. Highlights: Cell-free fetal DNA was generated using a human placental explant model. Lipopolysaccharide causes inflammation and cell death in placental explants. Inflammation does not increase cell-free fetal DNA release from placental explants. Generated DNA does not elicit inflammation from blood cells from pregnant women.