Histopathologic and transcriptome profiling identify novel trophoblast lineage-specific defects in preeclampsia

Preeclampsia (PE) is a heterogeneous disease which lacks pathophysiology-based subclassification. Current clinical classification is based on gestational age at diagnosis and severity of disease. However, PE placentas have heterogeneous findings on pathologic exam. We combined clinical, pathological, immunohistochemical (IHC), and transcriptomic profiling to better subclassify this disease. 303 PE and 1388 non-hypertensive controls were included, with subgroups of samples used for each analysis. Detailed clinical and placental pathologic data were abstracted from our Obstetric Registry. Tissue studio (Definiens) was used for IHC analysis. RNAseq was performed using Illumina-NovaSeq using our standard pipeline. We found that maternal vascular malperfusion (MVM) in the placenta is associated with preterm PE and small-for-gestation neonates, with further subclassification into groups with and without fetal vascular malperfusion (FVM). Interestingly, MVM with FVM was further characterized by loss of proliferative cytotrophoblast, as confirmed by p63 IHC. Finally, transcriptomic analysis identified pathways associated with hypoxia and reduced cell-proliferation in PE-MVM placentas, and further subclassified this group into syncytiotrophoblast (STB)hi and extravillous trophoblast (EVT)hi PE, confirmed by IHC for trophoblast lineage-specific markers. Our findings suggest that PE can be subclassified based on underlying pathophysiologic changes, allowing identification of pathways which can be targeted for diagnostic and therapeutic purposes. Total RNA-seq of placental RNA from non-hypertensive control and severe preeclampsia.