Comprehensive Metabolomics And Proteomics Investigation Into Siugr Phenotype Discordance Using Systematic And Integrative Bioinformatics Analysis

Selective intrauterine growth restriction(sIUGR)is one of the most serious complications among monochorionic diamniotic(MCDA)twins,manifesting in inconsistent weight growth among the fetuses.sIUGR twins suffers from prolonged gestational period and higher postpartum health risks.Therefore,low birthweight prevention and infant mortality reduction has been registered as one of the most explicit World Health Organisation's(WHO)public health policies.Current clinical researches into sIUGR mainly addresses the abnormal attachment of the umbilical cord and anatomy of the placenta,resulting in differential placental share,imbalance of blood perfusion or anastomosing between the placenta and blood vessels,supported by limited evidence.Ongoing biological researches on the other hand,emphasises on biochemical pathways alterations(such as affected key growth factors or transcriptional factor expression)related to intrauterine environment,nutritional deficiencies,and oxidative stress.So far,the minutiae of molecular mechanisms associated with intricate occurrences of sIUGR in MCDA twins remains largely unclear.sIUGR twins possesses identical genotype but unidentical phenotype,this unique characteristics presents an optimal research model in reflecting genetics-intrauterine environment interactions,which will undoubtedly highlight the value of sIUGR researches in the field of molecular biology.Systems biology is a holistic bioinformatics approach devoted to deciphering complex biological systems via closer examination of inter-biological componential changes(metabolome,proteome,transcriptome,and genome)to external factor influences and consequential phenotypic abnormalities.Systems biological approach makes up for the deficiencies of traditional bimolecular studies by providing a more comprehensive and integrated technique to better discover unabridged biological processes,such as biochemical pathways,behind various diseases as opposed to local instances.Therefore,this study fully explores the molecular mechanisms of sIUGR by employing metabolomics and proteomics analytical platforms,combined with integrative bioinformatics techniques to proffer new opportunities and potential therapeutic targets on the molecular level for sIUGR studies.PART ONE:METABOLOMICS ANALYSIS OF THE MCDA SIUGR TWIN PLACENTAObjective:To explain the phenotypic discordance in sIUGR twins by exploring potential changes in its placental metabolic mechanisms.Methods:GC-MS-based metabolomics was performed on the placenta samples from 15 pairs of sIUGR monochorionic twins,24 pairs of uncomplicated twins,and 14 FGR singletons.Supervised multivariate regression analysis and pathway analysis was used to compare control twins with sIUGR twins.GEE model,correlation network analysis and partial least square regression explored potential metabolic differences within sIUGR twin pairs.Logistic regression compared singleton FGR and sIUGR twins against control twins for significant metabolite concentration differences.Results:A significant elevation of placental amino acid N-a-acetyllysine was detected in sIUGR.Cis-4-hydroxproline was positively correlated to sIUGR twin pair weight discrepancy.Additionally,the sIUGR placental glutathione biochemical pathway was implicated by elevated pyroglutamic acid level alongside a decreased level of glutamate.Furthermore,an unusual increase in placental xenobiotic cyclic siloxanes was present in sIUGR placenta samples.We also exposed apparent disruptions in sIUGR placental amino acid and fatty acid metabolisms.Conclusion:This study uncovered key placental metabolic compositional deviations and disrupted placental metabolic processes in sIUGR twins.Presenting valuable new molecular information on the placental metabolome of sIUGR twins.PART TWO:METABOLOMICS ANALYSIS OF THE MCDA SIUGR TWIN UMBILICAL CORD BLOODObjective:To explain phenotypic discordance in sIUGR twins by investigating the umbilical cord plasma metabolome composition,with the aim of reflecting any fetomaternal metabolism abnormalities and potential metabolite transfer imbalances in sIUGR twins.Method:GC-MS-based metabolomics was performed on the umbilical cord plasma from 15 pairs of sIUGR monochorionic twins,24 pairs of uncomplicated twins,and 14 FGR singletons.Supervised multivariate regression analysis and pathway analysis was used to compare control twins with sIUGR twins.GEE model,correlation network analysis and partial least square regression explored potential metabolic differences within sIUGR twin pairs.Logistic regression compared singleton FGR and sIUGR twins against control twins for significant metabolite concentration differences.Results:A distinct difference was observed in the metabolic profile between the umbilical cord plasma of sIUGR and normal MCDA twins.Essential amino acids methionine and phenylalanine was significantly elevated,their respective biochemical pathways were also disrupted in the sIUGR umbilical cord plasma.Additionally,xenobiotic cyclic siloxanes levels was correlated to weight discrepancy sIUGR twins,appearing higher in the smaller twin's umbilical cord plasma.FGR singletons and sIUGR twins showed a significant different amino acid composition.Conclusion:This study indicated that an altered essential amino acids transfer are a large contributing factor to the phenotype disparity observed in sIUGR twins resulting in potential disruptions of multiple key fetomaternal metabolisms.Providing solid foundation for further in-depth molecular mechanism studies on sIUGR.PART THREE:PROTEOMICS AND INTEGRATIVE BIOINFORMATICS ANALYSIS ON SIUGR UMBILICAL CORD BLOODObjective:To explore valuable dynamic biochemical pathways associated with phenotype discordance in sIUGR twins by the means of comprehensive proteomics analysis and integrative systems biology.Methods:Proteomics were conducted on the umbilical cord blood samples from sIUGR twins and control twins using liquid chromatography-mass spectrometry(LC-MS),followed by systematic analysis including KEGG annotation,GO functional enrichment,and cluster analysis of differentially expressed proteins.Interdisciplinary bioinformatics integration analysis was implemented using MCODE method in Cytoscape to acquire significant molecular pathways related to the occurrence of sIUGR phenotype disparities.Results:A total of 6 upregulated proteins together with 149 down regulated proteins was observed in the sIUGR cord blood.GO enrichment analysis revealed significant protein disruptions associated with subcellular structures cytoskeleton and actin cytoskeleton.Additionally,GO structural analysis revealed prominent affected protein domains in sIUGR cord blood such zinc finger(LIM type),protein domains of tubulin/FtsZ,C-terminus,nucleophilic aminohydrolase,N,and nucleoside p-loop.KEGG protein pathway analysis indicated major perturbations in biochemical pathways such as regulation of actin cytoskeleton,tight junction,chemokine signaling pathway,and leukocyte transendothelial migration.Integration analysis revealed 22 protein-metabolite pathways to be of interest,among which the G6PD protein and its associated glutathione pathway has important value.Conclusion:Comprehensive sIUGR proteomics analysis exposed structural abnormalities in the umbilical cord endothelial cell cytoskeleton due to potential oxidative stress related events.As well as providing substantial integrative upstream and downstream related pathway information to ultimately understand the molecular basis of phenotypic discordance in sIUGR twins.