Effect Of Preeclampsia Differentially Expressed Gene LAIR-2on The Invasionof Trophoblast And Its Mechanism

Background and ObjectivePlacenta is essential for the intrauterine development of the human embryo. After theembryonic implantation, Extravillous cytotrophoblasts (EVT) invade the underlyingdecidua, then surround and migrate into the wall of the uterine spiral arteries, which resultsin the remodeling of uterine vasculature. This process plays a pivotal role in mammalianplacentation and is stringently regulated to ensure a successful pregnancy. Poor invasion ofEVT is believed to be associated with insufficient remodeling of the spiral arteries, which istypical of the pathological changes of miscarriage, preeclampsia and intrauterine growthrestriction. Conversely, excessive invasion leads to placenta percreta, persistenttrophoblastic disease or invasive cancer, such as choriocarcinoma. Elucidating theregulatory mechanism of trophoblast invasion is critical to understand these diseases.Preeclampsia (PE) is a multi-system disorder of human pregnancy that is characterizedby hypertension and proteinuria, posing a serious threat to maternal and child health.Studies on its etiology and pathogenesis have become an important research topic inobstetrics. Several generations of scholars have been active in preeclampsia, and severalpathogenesis theories have been proposed despite of their unclear pathogenesis mechanisms,including insufficient remodeling of the spiral arteries, excessive activation ofinflammatory immunization, vascular endothelial cell injury, genetic factor, nutritionaldeficiency, insulin resistance, etc. Among the above factors, insufficient remodeling of thespiral arteries is more widely accepted. Since1914, some scholars had proposed the uterineischemia theory based on the clinical signs of preeclampsia, most scholars believe thatuterine ischemia is due to ischemic placenta or trophoblast, resulting from placental spiralarteries recast obstacles, known as "shallow placental implantation." Uterine ischemia hasbeen reported to be related with the involvement of trophoblast invasion in the process ofembryo implantation. Recently, a large number of studies have shown that the changes in biological behavior oftrophoblast cells may be associated with abnormal gene expression, thus affecting thesecretion of trophoblast invasion-related proteases or other molecules; on the other hand, itmay be associated with the internal environment changes in hormone, immune status ofmaternal-fetal interface or cytokine in womb and the expression of genes controllingembryonic and placental development.In this study, the differentially expressed genes in preeclampsia placenta tissues werescreened and analyzed through the microarray technique, and LAIR-2was identified as themost differentially expressed gene. Our experiment aims to study the biology behaviorchange in trophoblastic cells under different expression circumstances and to explore theeffect of the differentially expressed genes in preeclampsia on the invasion of trophoblastcells and its mechanism.JEG-3cell lines are derived from human choriocarcinoma tissues and share manyproperties with the villous trophoblast in terms of their morphology, biochemical markers,and hormone secretion. Based on the JEG-3cells culture, we applies cDNA overexpressionand RNAi lentiviral vectors and cell transfection, Transwell, Western blot, RT-PCR andother experimental techniques to study and explore the impact of the preeclampsiadifferentially expressed gene LAIR-2on the human trophoblast invasion and its possiblemechanism.Major findings and conclusions:1. In this study, microarray technique was applied to select more than1,000geneswhich were differentially expressed between normal pregnancy placenta tissues andpreeclampsia placenta tissues. There were15kinds of genes which were significantlyup-regulated and displayed more than3-fold expression level differences in theexperimental group, and14kinds of genes which were significantly down-regulated withremarkable differences in gene expression (P <0.05). These genes are associated withpregnancy-related diseases, cell invasion, embryo development or pregnancy outcomes.Some genes are currently rarely reported. These findings provide a theoretical basis for thestudy of the preeclampsia at the molecular level.2. We adopted Western blot and PCR techniques to conduct a comparative study ofLAIR-2expression between the placental tissue in late pregnancy and placental tissue in normal pregnancy in preeclampsia patients. LAIR-2mRNA and protein expression inpreeclampsia patients during late pregnancy was higher than that in normal pregnancy. Thisresult verifies the first part of the experiment, suggesting a close relationship betweenLAIR-2and preeclampsia diseases. The effect of LAIR-2on the placental development inpreeclampsia patients and their relationship need further study.3.(1) LAIR-2cDNA overexpression and RNA interference lentiviral vectors weresuccessfully constructed by gene recombination technology and trophoblastic cell lineswere stably transfected.(2) The transduction of trophoblast cells with RNA interference lentiviraldown-regulated the LAIR-2expression, whereas the transduction of trophoblast cells withthe overexpressed cDNA lentiviral up-regulated the AIR-2expression.(3)Successful construction of LAIR-2overexpression and cell lines with genesilencing laid the foundation for the future research about LAIR-2functions.4.(1) LAIR-2, as being a differentially expressed gene in preeclampsia, participated inregulating the biological behavior of trophoblastic cells.(2) LAIR-2affected the trophoblast proliferation, migration and invasion. The LAIR-2up-regulation decreased the trophoblast proliferation, migration and invasion, whereasLAIR-2down-regulation increased the above capabilities.(3) LAIR-2affected the expression of MMPs in trophoblast. LAIR-2up-regulationdecreased the expression of MMP-2, MMP-9and MMP-14, whereas its down-regulationincreased their expression.The above results indicate that: LAIR-2may play an important role in preeclampsiacharacterized with insufficient trophoblast invasion, and its role in affecting the expressionof MMPs is an important intermediate link and mechanism. In-depth study of LAIR-2helpsto clarify the pathogenesis of preeclampsia, and to provide new directions for the earlydiagnosis and treatment of preeclampsia in clinical practice.