Differentially expressed transcripts associated with depressive symptoms during pregnancy and postpartum
Peripartum depression can have severe impact on the mother's and the infant's health. Yet, its biological underpinnings are largely unknown. The present study sought to identify transcriptomic signatures of depressive symptoms  during pregnancy and postpartum. Blood samples were collected during late pregnancy or early postpartum for mRNA isolation and sequencing, while depressive symptoms were assessed using the Edinburgh Postnatal Depression Scale. Stratifying according to the timepoint samples were collected, differentially expressed genes (DEGs) were identified by (1) comparing mRNA levels between the symptom trajectory groups, and (2) correlating with EPDS scores. DEGs for samples collected late pregnancy, but not postpartum, were associated with depressive symptoms occurring only during pregnancy or persisting postpartum, compared with controls. There were 16 upregulated and 109 downregulated DEGs significantly associated with changes in EPDS score at week 32 among samples collected late pregnancy. Gene Set Enrichment Analysis identified immune response and cell motility as processes linked to these DEGs. Hypothesis-based analysis on previously identified postpartum depressive symptoms-related DEGs, replicated a positive association between expression of immune-related genes ISG15 and RSAD2 with postpartum-onset depressive symptoms, both at samples taken during late pregnancy and postpartum. The present findings point to transcriptomic signatures associated with depressive symptoms, mostly related to immune system dysregulation. Overall design: Nested case-control study; blood samples were collected in late pregnancy or postparum from women with of without depressive symptomes.