Aims: Inflammatory processes are present during preeclampsia and in normal pregnancy. Maternal inflammatory reactions may change towards term. Our objective was to evaluate genome signaling in blood during preeclampsia and towards term using microarrays.

Methods: RNA microarrays (Illumina) were conducted on blood from preeclamptic pregnancies delivered preterm, normal pregnancies at term and normal pregnancies at gestational week 31. Two statistical methods (Q-value cut-off 1%) identified data structures in the three groups and retrieved activated genes along a time axis and a diseased-healthy axis. Signaling genes were localized within known pathways and gene sets, and genes associated with inflammation were identified.

Results: Early onset preeclampsia and term pregnancies both showed distinct expression patterns when compared to normal pregnancy at gestational week 31. In preeclampsia, 19 genes were differentially expressed, including a down-regulation of CC-chemokine receptor 3 (CCR3). Among the 183 differentially expressed genes towards term, tumor necrosis factor superfamily member 15 (TNFSF15) was up-regulated and interferon-γ receptor 2 (IFNGR2) and CXC-chemokine receptor type 4 (CXCR4) were down-regulated. Seven of the genes were similarly changed during preeclampsia and towards term.

Conclusions: A possible type 1 immune response was identified both during preeclampsia and towards term. In pre-eclampsia a premature activation of leucocytes might be present.