Characterization of the placental transcriptome through mid to late gestation in the mare.
Authors: Loux Shavahn C, Dini Pouya, El-Sheikh Ali Hossam, Kalbfleisch Theodore, Ball Barry A
Journal: PloS one
Summary
# Editorial Summary Understanding how the equine placenta adapts throughout pregnancy is fundamental to supporting healthy fetal development, yet gene expression patterns beyond early pregnancy have remained largely unexplored in the mare. Researchers used RNA-sequencing to map transcriptomic changes across both the fetal (chorioallantoic) and maternal (endometrial) components of the placenta at four, six, ten and eleven months of gestation. Whilst the endometrium showed substantial dynamic remodelling with 47% of genes altering expression over this period, the fetal component proved more stable at 29%, though both tissues expressed approximately 95% of genes in common and shared similar highly-expressed gene profiles. The most abundant transcripts fell into distinct functional categories: endocrine and immune-related genes, iron-binding and antioxidant proteins, extracellular matrix components, and notably, serine protease inhibitors (SERPINA3, SERPINA6, SERPINA14, SPINK7 and SPINK9)—likely critical for modulating inflammation and supporting the maternal-fetal interface. For equine professionals, these findings illuminate the physiological mechanisms underpinning placental function across gestation and provide a reference framework for investigating pregnancy complications, nutritional demands, and the timing of physiological transitions in mares.
Read the full abstract on PubMed
Practical Takeaways
- •The placenta undergoes major remodeling throughout pregnancy; understanding this dynamic process provides a foundation for investigating pregnancy complications and loss
- •The abundance of immune-related transcripts and serine protease inhibitors suggests the placenta is actively managing maternal-fetal immune tolerance throughout gestation
- •This RNA-sequencing dataset and methodology establish the horse as a valuable model for studying placental biology relevant to other species, potentially improving diagnostic approaches to pregnancy disorders
Key Findings
- •47% of endometrial genes and 29% of chorioallantoic genes changed expression significantly throughout mid-to-late gestation (4-11 months)
- •Approximately 95% of genes were expressed in both fetal and maternal placental tissues, with high conservation of the 20 most highly expressed genes (9/20 shared)
- •Most highly expressed genes fell into categories including immune function, iron-binding proteins, extracellular matrix proteins, transport proteins and antioxidants, with serine protease inhibitors particularly abundant
- •Maternal and fetal placental components were successfully separated with only ~8% chorioallantoic contamination in endometrial samples, enabling clean tissue-specific analysis