Advanced molecular techniques in pregnancy research: proteomics and genomics--a workshop report

Utility of proteomics in obstetric disorders: a review

The study of proteomics could explain many aspects of obstetric disorders. We undertook this review with the aim of assessing the utility of proteomics in the specialty of obstetrics. We searched the electronic databases of MEDLINE, EBSCOhost, BVS Bireme, and SciELO, using various search terms with the assistance of a librarian. We considered cohort studies, case-control studies, case series, and systematic review articles published until October 2014 in the English or Spanish language, and evaluated their quality and the internal validity of the evidence provided. Two reviewers extracted the data independently, then both researchers simultaneously revised the data later, to arrive at a consensus. The search retrieved 1,158 papers, of which 965 were excluded for being duplicates, not relevant, or unrelated studies. A further 86 papers were excluded for being guidelines, protocols, or case reports, along with another 64 that did not contain relevant information, leaving 43 studies for inclusion. Many of these studies showed the utility of proteomic techniques for prediction, pathophysiology, diagnosis, management, monitoring, and prognosis of pre-eclampsia, perinatal infection, premature rupture of membranes, preterm birth, intrauterine growth restriction, and ectopic pregnancy. Proteomic techniques have enormous clinical significance and constitute an invaluable weapon in the management of obstetric disorders that increase maternal and perinatal morbidity and mortality.

Characterization of the laser-based release of micropallets from arrays

The micropallet array system uses a pulsed laser to release pallets tens of microns to hundreds of micrometers in size from a larger array, enabling selective isolation of single cells adherent to the pallets. We characterize the laser-based release of pallets with respect to pallet array and laser parameters. The threshold laser energy required for pallet release increases linearly with the area of the pallet in contact with the underlying glass substrate. The spacing of the pallets within an array as well as the thickness or height of the pallet does not impact the energy required to release a pallet. Delivery of multiple laser pulses decreases the energy/pulse required for pallet release when the pallets were 100 microm or greater on a side. In addition to the square pallets, complex structures such as cantilevers and spirals could be released without damage using the pulsed laser. Identification of the pallet-array variables influencing the energy required for pallet release as well as strategies to minimize this energy will prove critical in optimizing the release of pallets with cells on the arrays.

Toward a better understanding of preeclampsia: Comparative proteomic analysis of preeclamptic placentas

Preeclampsia (PE), a pregnancy-specific syndrome of hypertension, proteinuria, and other systemic disturbances, is a state of widespread endothelial dysfunction secondary to defective placentation. Morphologically, the current data displayed degenerative and apoptotic changes in the mitochondria and villous trophoblasts of preeclamptic placenta. To reveal the superimposing alterations in placental proteins that might explain the pathophysiology of PE, we performed 2-DE MALDI-TOF MS/MS proteomics analysis of differentially expressed placental proteins with placenta from eight normal and eight preeclamptic pregnancies. The identified proteins were confirmed by Western blot analysis. We also performed morphologic evaluation of preeclamptic placentas under both electron and light microscopy. The results disclosed the marked overexpression of chaperonin 60, GST, VDAC, ERp29, and cathepsin D in PE. These proteomics findings clearly suggest the possible cellular battle against mitochondria-originated oxidative stress during PE that either end up with recovery or apoptosis. These results provide a better understanding of proteomic alterations and may help in clarification of stress-related changes in preeclamptic placentas.

Microarray analysis of differentially expressed fetal genes in placental tissue derived from early and late onset severe pre-eclampsia

Although it has been well documented that pre-eclampsia is caused by a combination of maternal and fetal susceptibility genes, little is known about the precise etiology of this complicated disorder. To investigate how the expression of fetal genes contributes to the mechanisms underlying the progression of this disease, we have analyzed differentially expressed genes using placentas from 13 normal pregnancies and 14 pregnancies with severe pre-eclampsia. We performed genome-wide expression profiling using high-density oligonucleotide microarrays, followed by validation using real-time PCR. Among the 47,000 genes that were screened in the microarray, 137 genes were found to be differentially expressed between normal and pre-eclamptic tissues. Among these candidates, 70 were up-regulated and 67 were down-regulated. The up-regulated genes included leptin and inhibin A, which are well-known biological markers for pre-eclampsia, as well as FLT1, which was recently proved to be tightly linked with the etiology of this disease. Gene ontology analysis further revealed several biological processes that could be associated with the development of pre-eclampsia, including response to stress, host-pathogen interactions, lipid metabolism, and carbohydrate metabolism. Analyses of biological mechanisms highlighted some important pathways that may be involved in this disorder, such as the TGF-beta and CEBPA-related pathways. Furthermore, when our present subjects were classified as either severe cases of early onset or late onset pre-eclampsia, the expression of 11 genes could be correlated with the severity of this disorder. These genes may therefore prove to be novel biological markers by which the severity of this condition could be predicted. Our data are likely to be a useful future resource in the elucidation of the disease-process and in the identification of novel markers for pre-eclampsia.

IGFBP1 and Follistatin-like 3 genes are significantly up-regulated in expression profiles of the IUGR placenta

To date, the clinicopathological features of intrauterine growth restriction (IUGR) are not clearly understood, and no effective therapy has been established for IUGR. This is the first study that uses microarray analysis to identify differentially expressed genes in the IUGR placenta. The expression profiles of a total of 9121 genes were examined by cDNA microarray analysis, using mRNA from an appropriate gestational age (AGA) placenta and an IUGR placenta from discordant dichorionic twins. Up-regulation of the IGFBP1 and Follistatin-like 3 genes was detected in the IUGR placenta, with a balanced differential degree of 20.7+/-1.3 and 13.1+/-2.1, respectively, while the balanced differential degrees of other genes were 2.6 or less. The expressions of the IGFBP1 and Follistatin-like 3 genes in four single IUGR and four AGA placentas were also examined by RT-PCR. Consistent with our data in discordant chorionic twin placentas, three of four IUGR placentas showed up-regulation of the IGFBP1 and all four IUGR placentas showed upregulation of Follistatin-like 3 genes when compared to the AGA placentas. Our results suggest that IGFBP1 and Follistatin-like 3 are highly up-regulated in IUGR in the placenta. IGFBP1 and Follistatin-like 3 are known critical regulators of fetal growth and differentiation. Pathways associated with these genes might be important for the pathogenesis of IUGR.

Global approach to perinatal medicine: functional genomics and proteomics

Functional genomics (transcriptomics and proteomics) is a global, systematic and comprehensive approach to the identification and description of the processes and pathways involved in normal and abnormal physiological states. The functional genomics methods most applied today are DNA microarrays and proteomics methods, primarily two-dimensional gel electrophoresis coupled with mass spectrometry. To date, interesting research has been carried out, representing milestones for future implementation of functional genomics/proteomics in perinatal medicine. For instance, possible biomarkers of pre-eclampsia, preterm labor and gestational trophoblastic diseases have been discovered. Further systematic examination of differentially regulated genes and proteins in maternal and fetal tissues and fluids will be required. However, high-throughput technologies reflect biological fluctuations and methodological errors. Large amounts of such different data challenge the performance and capacity of the statistical tools and software available at present. Further major developments in this field are pending and the intellectual investment will certainly result in clinical advances.