Free Fetal DNA Incites a Local Inflammatory Response in Murine Placentae Via TLR-9 Resulting in Fetal Loss and Preterm Delivery
Andrea S Nugent, Sinead Corr, Sean Daly, Louise Keogh, Cara Martin, Kate Fitzgerald, Luke A O'Neill, John J O'Leary. Coombe Women and Infants University Hospital, Dublin, Ireland; Trinity College Dublin, Dublin, Ireland; University Massachusettes Medical School, Boston, MA
Background: Free fetal DNA is in the maternal circulation during normal pregnancy. Inflammatory disorders such as pre-term delivery and pre-eclampsia have been have higher levels than normal pregnancy. Since fetal DNA has increased hypo-methylated CPG content compared to adult DNA, we questioned whether it may act as a ligand for TLR-9 in an in vivo model.
Design: Wildtype and TLR-9 deficient female C57/bl6 mice were mated and became pregnant. On day 10- 14 of gestation, they were injected intra-peritoneally with 300μg/ml of free fetal DNA. After 48 hours, a post-mortem hysterectomy was performed and grossly examined. Immunohistochemistry techniques were applied to cross sections of placental sites and collected sera.
Results: The resorption rate of pregnancy in the wildtype mice was 85% compared with the TLR-9 deficient mice (12%).
In 2 of the 4 wildtype injected, the sacs were remarkably smaller in size and weight suggesting preterm delivery and cannibalisation. Staining the placental site for IL-6 and TNF demonstrated a marked increase in inflammatory cells and protein within the wildtype mice compared to the TLR-9 deficient mice.
Conclusions: High Concentrations of Free fetal DNA are immunotoxic to fetuses in pregnant wildtype mice. The presence of which results in death, resorption, and pre-term delivery. The absence of this response in TLR-9 deficient mice suggests it is likely to be TLR-9 dependant. Considering the flux of free fetal DNA in human pregnancies and the high levels noted in those complicated by pre term labour and pre-ecampsia, it is likely that TLR-9 has a role to play in these processes.
Category: Gynecologic & Obstetrics
Wednesday, March 21, 2012 1:00 PM
Poster Session VI # 214, Wednesday Afternoon