Finding NEMO in preeclampsia

Abstract

Background: The mechanism of preeclampsia and its way of inheritance are still a mystery. Biochemical and immunochemical studies reveal a substantial increase in tumor necrosis factor alpha, interleukin-1 beta, and interleukin-6 concentrations in the blood of women with preeclampsia. The level of these factors is regulated by nuclear facxtor-kappa B, whose activation in a classical pathway requires inhibitory kappa B kinase gamma (known as NEMO or IKBKG). Moreover, NEMO can schedule between cytoplasma and the nucleus. In the nucleus, IKBKG interacts with other proteins, and thus, it is implicated in the regulation of different gene expressions, which are related to cell cycle progression, proliferation, differentiation, and apoptosis.

Objective: This is the first study investigating the association between the level of NEMO gene expression and the presence of preeclampsia. We tested the hypothesis that the simultaneous increase in NEMO gene expression both in the mother and her fetus may be responsible for the preeclampsia development. Moreover, the relationships between clinical risk factors of preeclampsia and the levels of NEMO gene expression in blood, umbilical cord blood, and placentas were investigated.

Study design: A total of 91 women (43 preeclamptic women and 48 controls) and their children were examined. Real-time reverse transcription-polymerase chain reaction was used to assess the amount total NEMO messenger ribonucleic acid (mRNA) content and the mRNA level of each NEMO transcript from exons 1A, 1B, and 1C in maternal blood, umbilical cord blood, and placentas. Univariate analyses and correlation tests were performed to examine the association between NEMO gene expression and preeclampsia.

Results: Newborn weight and height, maternal platelet number, and gestational age (week of delivery) were lower in the group of women with preeclampsia than controls. NEMO gene expression level was found to be almost 7 times higher in the group of women with preeclampsia than healthy controls. The correlation analysis found that a simultaneous increase in the expression level of total NEMO mRNA in maternal blood and the mRNA for total NEMO (Rs = 0.311, P < .05), transcripts 1A (Rs = 0.463, P < .01), 1B (Rs = 0.454, P < .01), and 1C (Rs = 0.563, P < .001) in fetal blood was observed in preeclamptic pregnancies. In addition, the mRNA levels for total NEMO and transcripts 1A, 1B, and 1C were lower in placentas derived from pregnancies complicated by preeclampsia.

Conclusion: Simultaneous increase of NEMO gene expression in maternal and fetal blood seems to be relevant for preeclampsia development. The results of our study also suggest that a decreased NEMO gene expression level in preeclamptic placentas may be the main reason for their intensified apoptosis.

Keywords: NEMO gene; preeclampsia; real-time reverse transcription–polymerase chain reaction.