RNA-seq analysis of human placenta to elucidate the pathomechanism of spontaneous preterm birth

The pathogenesis of spontaneous preterm birth (PTB) is largely unknown. We conducted RNA-seq transcriptomic analysis, qRT-PCR and ELISA on fresh placental villous tissue from 20 spontaneous preterm and 20 spontaneous term deliveries, to identify genes and signalling pathways involved in the pathogenesis of PTB. Our differential gene expression, gene ontology and pathway analysis revealed several dysregulated genes, including OCLN, OPTN, KRT7, WNT7A, RSPO4, BAMBI, NFATC4, SLC6A13, SLC6A17, SLC26A8 and KLF8, associated with altered trophoblast functions. We identified dysregulated Wnt, oxytocin and cellular senescence signalling pathways in preterm placentas, where augmented Wnt signalling could play a pivotal role in the pathogenesis of PTB due to its diverse biological functions. We provide fresh molecular insight into the pathogenesis of spontaneous PTB, which may drive further studies to develop new predictive biomarkers and therapeutics. Overall design: Total RNA was extracted from fresh villous tissue from 20 spontaneous preterm (cases) and 20 term (controls) human placentas. Bulk NGS RNA sequencing was conducted using MinION Oxford Nanopore Technology. Differential gene expression analysis was conducted to identify significantly differentially expressed genes in the preterm placenta. Gene ontology and signalling pathway analyses were conducted using upregulated and downregulated gene sets separately. A sub-group analysis was also conducted to differentiate gene expression profiles of male and female preterm placentas compared to term placentas, to elucidate the influences of fetal sex differences on preterm labour.