Adverse neonatal outcomes are associated with a sex-specific placental inflammatory profile

Background and objective: The placenta is crucial for fetal development; altered function is associated with complications and adverse neonatal outcomes. Our goal was to ascertain changes in the placental transcriptome in relation to neonatal outcome and fetal/placental sex. Study Design: 72 mother-baby dyads were included. Demographic, obstetrical, neonatal and infant health data were obtained through medical charts. Adverse neonatal outcome was defined as the presence of a pulmonary, cardiac, neurological or other health complication. Bulk RNA-sequencing of placental biopsies was obtained. P-value < 0.05 was considered statistically significant. Results: Neonates experiencing adverse outcomes were more likely to be premature or have lower birth weights. Analysis of the placental transcriptome revealed a predominant inflammatory profile in pregnancies associated with adverse neonatal outcomes with the top pathways being related to immune and inflammatory responses. Amongst differently expressed genes (DEGs), 1237 were upregulated and 239 were downregulated in adverse vs no adverse outcomes. Furthermore, sex-specific differences in gene expression were observed and indicated that male and female placentas displayed unique DEGs in association with adverse outcomes. Indeed, no DEG was observed in female placentas when comparing those without vs with adverse neonatal outcomes, as opposed to 1279 DEGs in male placentas, of which 91% were up-regulated in adverse subgroups. Conclusions: These findings highlight that inflammatory pathways are upregulated in placentas in association with adverse neonatal outcomes, and showcase the importance of the fetal sex in understanding neonatal health. The placenta provides a unique tool for early identification of high-risk infants rapidly after delivery. Overall design: Placental villus biopsies were collected rapidly after delivery and placed into RNA later for 24h before being stored at -80ºC until processing. mRNA was extracted using the RNeasy mini kit (Qiagen, Canada) following manufacturer instructions. RNA was quantified by spectrophotometry (Nanodrop 8000, Thermo Fisher Scientific, Canada) and the quality was assessed using the RNA Integrity Number (RIN = 7; Agilent 2100 Bioanalyzer, USA). Libraries were done using the TruSeq RNA Library Kit v2 (Illumina, USA) and fragment size was validated on a Bioanalyzer (Agilent 2100, USA). Libraries were sequenced using the HiSeq 4000 system (Illumina, USA) at the “Integrated Clinical Genomics Centre in Pediatrics”at the CHUSJ.