Effect of Maternal Body Mass Index on the Transcriptomic Network of Human First-Trimester Chorionic Villi

The relationship between fertility and maternal body weight is shaped like an inverted "U," meaning that fertility is negatively affected in overweight or underweight women. Timely and appropriate maternal-fetal interaction is a crucial part of successful pregnancy. However, it is not clear how body weight affects maternal-fetal interaction. Placental villi are the bridge for maternal-fetal interaction. Therefore, we collected villi from pregnant women with different body mass indexes (BMI), who voluntarily underwent induced abortion, to construct a molecular network via RNA-seq. Surprisingly, based on global and significant gene network analysis, we found that dysregulation of inflammatory reaction, cell adhesion, and immune response were the most significantly enriched pathways. We also conducted dynamic gene expression analysis with BMI as a variable, and identified several distinct clusters. Among them, cluster 9 showed an inverted "U" shape and genes in it were mainly enriched in chemical synaptic transmission and cell-cell adhesion via plasma-membrane adhesion molecules. Additionally, genes in the "U" shaped cluster (cluster 5) were enriched in regulation of adaptive immune response based on somatic recombination of immune receptors built from immunoglobulin superfamily domains and negative regulation of immune response. We thus conclude that maternal body weight can affect maternal-fetal interaction through alterations or aberrant activation of inflammatory reaction and immune response. Regulating inflammatory reaction may be a potential therapeutic strategy to improve fertility of overweight and underweight people.