Background : Gestational diabetes mellitus (GDM), the most common metabolic complication of pregnancy, is influenced by the placenta, and its prevalence directly increases with obesity. However, the obvious mechanism of maternal and neonatal complications in GDM is not identified. Therefore, to define the mechanism of GDM-associated maternal and neonatal complications, accurate qualified studies using Next generation sequencing are required. 
Methods : We optimized RNA extraction from human placentas from control group, GDM group, and GDM-associated complications group. Genome-wide gene expression analysis was performed on the RNA extracted from the placenta of GDM and GDM-associated complications and normal placentae. To identify the transcription regulators to regulate the GDM-associated complications, IPA analysis was used among groups. The protein expression of predictive biomarkers was validated using immunohistochemical analysis. 
Results : Diverse differentially expressed genes (DEGs) specifically discriminated GDM from matched control subjects, and GDM-complications from GDM subjects. 36 genes significantly differentiated among 3 groups, and IPA analysis revealed the PD1 expression was the new predictive regulator in GDM associated complications. Moreover, PDL1 expression was significantly elevated in GDM group compared to control group. 
Conclusions : Our data firstly indicate a biological link between PD1-PDL1 signaling involved in GDM-associated complications, and these results suggest the novel predictive role of PD1-PDL1 signaling in GDM.

PD1-PDL1 expression as the new predictive biomarkers of gestational diabetes mellitus