Differential expression of microRNA-206 and its target genes in preeclampsia.

Preeclampsia is a syndrome that occurs during the second half of pregnancy in approximately 1–5% of women in the developed world [1]. Preeclampsia is broadly defined by the International Society for the Study of Hypertension in Pregnancy (ISSHP) as de-novo development of hypertension and proteinuria after the 20th week of gestation. The disease contributes to maternal and perinatal morbidity and mortality as well as conferring increased long-term risk of chronic illnesses. The only effective treatment is delivery both of the baby and the placenta; therefore, the basis of the disease is thought to be predominantly due to placental dysfunction. The development of preeclampsia is multifactorial and remains incompletely understood. MicroRNAs (miRNAs) are small noncoding RNAs that act at a posttranscriptional level to degrade target genes recognised by complementary base pairing in the 3’ untranslated region of the mRNA. miRNAs may provide a novel strategy for better understanding of preeclampsia and its diagnosis. miRNAs have been shown to play a functional role in physiological processes important in pregnancy such as placental development, trophoblast proliferation and migration and angiogenesis [2]. miRNAs also exist in circulation within a number of body fluids. Currently, the origin of circulating miRNAs is not fully understood and therefore it is not known how their levels are altered in disease, or if they have a particular target via which they can exert a functional role. Circulating miRNAs are protected from degradation by specific proteins [3,4] within exosomes [5] or microparticles [6]. This suggests that miRNA in plasma may serve an important role requiring their integrity to be preserved. Few studies into preeclampsia have assessed levels of circulating miRNAs in the plasma and have either focused on late gestation or have lacked translation into relevant tissues [7–9]. Microarray technology allows the expression of many miRNAs to be detected simultaneously creating a patient-specific profile. In this pilot study, we have used an OpenArray microarray to complete a nonbiased screen of circulating miRNA expression in plasma samples taken from 18 women who developed preeclampsia and 18 matched women with normotensive pregnancies at 16 and 28 weeks of gestation. We hypothesized that there are detectable changes in circulating miRNA expression at the preclinical stage of preeclampsia. Our aim was to identify these miRNAs and evaluate their relevance as an early biomarker and their potential pathological role in disease.