OS045. Multi-dimensional protein identification technology analysis of syncytiotrophoblast vesicles released from...

In pre-eclampsia, the consequences of poor placentation lead to the second stage of pre-eclampsia, which involves activation of a maternal systemic inflammatory response (MSIR). Endothelial and other inflammatory cellular dysfunction cause the diverse features which characterise the disorder. We have previously shown that syncytiotrophoblast microvesicles (STBM) are pro-inflammatory and circulate in increased amounts in pre-eclamptic women. We hypothesise that multiple placental "danger signals" are carried by STBM into the maternal circulation in increased amounts in PE with pro-inflammatory, anti-angiogenic and pro-coagulant activity, implicating STBM in the pathophysiology of PE.

To characterise the proteins carried by STBM from normal and PE placentas. For the first time multi-dimensional protein identification technology (MudPIT) was used to derive the proteome profiles of normal and PE placenta STBM.

STBM were prepared from placentas (normal term: n=9 and PE: n=5) by dual lobe perfusion, isolated by ultracentrifugation and stored at -80°C. Normal and PE derived placenta STBM pools were then subjected to MudPIT analysis.

538 proteins unique to PE STBM, 604 proteins unique to normal STBM and 1421 proteins common to both preparations were found. Preliminary analysis indicates the presence of alarmins (HSP70, and galectin 3), exosomal proteins (CD63,CD9,CD81), immunoregulatory molecules (CD26,CD200,CD47,Galectin 1), complement and complement regulatory molecules (C1q,C3,CD55,CD59 and vitronectin), amino acid transporters (CD98) and anti-angiogenic molecules (endoglin). Our analysis also reveals that proteins known to be elevated in blood before, or at, the time of pre-eclampsia are elevated or unique in STBM from PE placentas, including Fetuin A, Inter-alpha (globulin) inhibitor H4, Serum amyloid P component, Apolipoprotein H (or B2GP1) and Apolipoprotein AII. Thus, as predicted, a large number of circulating molecules are associated with STBM. The inter-relationships between proteins that are unique to either PE or normal pregnancy and the processes in which they are involved are being determined by Ingenuity Pathways Analysis software. In terms of biofunctions, preliminary analysis shows that proteins unique to PE STBM have a highly significant association (p<10(-11)) with 6 disease pathways including inflammatory, immunological, cardiovascular and reproductive system diseases and organ injury, whereas for proteins unique to normal STBM only protein synthesis was significant at the same level.

STBM contain a heterogeneous population of vesicles that convey a large repertoire of placental proteins into the maternal circulation. The profound differences between PE and normal STBM indicate their pro-inflammatory potential.