Characterisation of proteins and RNA expressed in syncytiotrophoblast membrane extracellular vesicles (STB-EVS) in preeclampsia

Introduction: Preeclampsia is a complication of pregnancy that affects 2-8 % of women worldwide. It is one of the leading causes of maternal deaths and premature birth. It is diagnosed by elevated blood pressure (≥ 140/90 mmHg), proteinuria, and/or end-organ damage. Although the precise mechanisms are not fully elucidated, the placenta is involved in this disease process. However, one theory is the role of extracellular vesicles STB-EVs, which are membrane-bound biomolecules that range between 30-1000 nm in size released by the placenta and detected in the circulation. STB-EVs have been reported to be higher in the circulation in PE compared to Normal pregnancy. In addition, the phenotype of the STB-EVs is believed to be different in PE compared to NP. However, it is unclear if the clinical manifestations attributable to STB-EVs in PE are a) because PE STB-EVs are more abundant in circulation, b) because they are of a different phenotype (bigger with a different cargo), or c) a combination of both. This thesis builds on the second premise. Aim: My work explores the possibility that STB-EVs can act as biomarkers and mechanistic and therapeutic targets in PE. Methodology: I have isolated and characterised STB-EVs from the placenta of 8 PE and 6 NP patients via ex vivo dual lobe placenta perfusion. I subjected these materials through mass spectrometry, coding RNA, and small RNA sequencing and multi-omics (transcriptomics, proteomics, and integrated multi-omics) data analysis. This is the first study of its kind in the field. Results: My analysis identified a difference in STB-EV cargoes' transcriptomic and proteomic profiles between preeclampsia (PE) and normal pregnancy (NP). I then identified and verified the differential expression of transcripts (FLNB, COL17A1, SLC45A4, LEP, HTRA4, PAPP A2, EBI3, HSD17B1, FSTL3, INHBA, SIGLEC6, and CGB3), microRNA (hsa-miR-193b-5p, hsa-miR-324-5p, hsa-miR-652-3p, hsa-miR-3196, hsa-miR-9-5p, hsa-miR-421, and hsa-miR 210-3p in the Medium/large STB-EVs) and proteins (FLNB (filamin B), COL17A1 (Collagen 17A1), PAPP-A2 (Pappalysin-A2), and SR-BI (Scavenger Receptor Class B Type 1)) for potential use as biomarkers in preeclampsia. My analysis also identified 1) interesting mechanistic processes such as abnormal protein metabolism, which may be responsible for the clinical and pathological presentation of preeclamptic patients, and 2) molecular clusters that may explain variations in the presentation of PE and potential therapeutic candidates (ceforamide, thiamine, dexibuprofen) Conclusions: I performed comprehensive profiling of the transcriptome, proteome and pathways in PE by analysing my three different sample subtypes (placenta, M/L STB-EVs and S STB-EVs). I identified differentially expressed biomolecules (proteins and RNAs) and uncovered mechanistic pathways which may be important in the pathophysiology of PE and could potentially be used in future studies of disease mechanisms and as biomarkers.