B cells acquire a unique and differential transcriptomic profile during pregnancy in mice

Pregnancy significantly alters B cells development and function. B cell activation is initiated by antigens specific binding to the BCR, leading to an intricate signaling pathway responsible for B cell survival, proliferation, antigen processing/presentation and antibody production. We performed a genome-wide transcriptome profiling in splenic B cells from pregnant (P) and non-pregnant (NP) mice. We identified 1136 genes with differential expression in B cells from P mice (625 up- and 511 down-regulated) compared to NP animals. In silico analysis showed that B cell activation through BCR-signaling pathway as well as antigen processing/presentation and TLR cascades seems to be lowered during pregnancy. Further RT-qPCR analysis confirmed these data. In addition, B cells from pregnant women stimulated in vitro through BCR in combination with CpG, produced significantly lower levels of cytokines compared to non-pregnant women. Our results suggest that B cells acquire a state of hypo-responsiveness during gestation, probably as part of the maternal immune strategy for fetal tolerance. However, our results also open new avenues to understand why pregnant women are at highest risk for some infections. We performed a genome-wide transcriptome profiling in splenic B cells from 4 pregnant (P) and 4 non-pregnant (NP) mice.