Preeclampsia is associated with reduced ISG15 levels impairing extravillous trophoblast invasion.

Preeclampsia (PE), a major cause of excess maternal and perinatal morbidity and mortality, has a worldwide prevalence of 2-8%. Excess inflammation with immune maladaptation in the maternal decidua causes shallow trophoblast invasion, resulting in incomplete spiral artery transformation that are characteristic of PE. To mimic the separate and combined paracrine effects of IL-11 and IL-6 on trophoblasts in normal versus preeclamptic pregnancies, primary cytotrophoblast (CTB) cultures treated with IL-11 or IL-6 or IL-11+IL-6 were analyzed by whole genome microarray. These microarray analyses revealed that IL-11 treated CTBs displayed a total of 283 differentially expressed genes (159 of which are up-regulated and 124 are down-regulated), whereas IL-6 treated CTBs displayed a total of 243 differentially expressed genes (120 are up-regulated and 123 are down-regulated) compared control group. However, IL-11+IL-6 co-treated CTBs exhibited 276 differentially expressed genes (146 of which are up-regulated and 130 are down-regulated) compared to control group. Since IL-11 and IL-6 can compete to activate target cells through binding their shared receptor, the global transcription repertoire of CTB cultures treated with IL-11+IL-6 was compared to those treated with either IL-11 or IL-6. A total of seven genes are differentially regulated by IL-11+IL-6 co-treatment vs. treatment with IL-11 alone (four of which are up-regulated and three down-regulated), whereas compared to IL-6 alone, a total of six genes are differentially regulated by IL-6+IL-11 (all of which are down-regulated). Microarray results of this study support that co-existence of IL-6 and IL-11 impairs the global transcription repertoire of trophoblasts compared to the presence of IL-11 alone, most probably through a mechanism that partial or complete IL-6 binding to gp130 blocks IL-11 action. Importantly, ISG15 is the only commonly affected gene and is downregulated by IL-6 and IL-11 co-treatment compared to control or treatment with either IL-11 or IL-6 alone, suggesting its involvement in PE. Primary cultured cytotrophoblasts (CTBs) obtained from term placental samples were subjected to RNA extraction, quantification, and evulation, followed by hybridization on Illumina beadchip. Three biological replicates were used (N=12 total samples).