Expression and Distribution of Src Kinase Lyn in the Placenta of Patients with Preeclampsia

Src family kinases (SFKs) constitute a major non-receptor tyrosine kinase class that regulate processes important for pregnancy. We profiled placental SFKs to assess cell-specific expression, tissue localization, and clinical associations in early-onset preeclampsia (PE). Placental SFK transcripts were analyzed using bulk RNA sequencing discovery (GSE203507; n=15 PE, n=15 controls) and external validation (GSE114691; n=40 PE, n=21 controls) cohorts. Single-cell and single-nucleus RNA sequencing atlases mapped cell-specific expression. Computational deconvolution and causal mediation analyses were applied to bulk datasets. Findings were cross-validated by real-time quantitative PCR (qPCR; n=9 early-onset PE, n=7 controls) and immunohistochemistry (IHC). Transcriptomic data showed that LYN was the sole SFK member consistently elevated in early-onset PE placentas across discovery (1.8-fold, FDR<0.01) and validation cohorts (2.2-fold, FDR<0.001). Elevation was verified by qPCR (p<0.0001) and remained significant after adjusting for clinical covariates. Placental LYN abundance correlated positively with maximum antepartum maternal systolic blood pressure (r=0.63, p<0.01). Single-cell transcriptome atlases demonstrated LYN enrichment in myeloid lineages, extravillous trophoblasts, and syncytiotrophoblast (SCT). Deconvolution and mediation analyses indicated that altered tissue composition and increased per-cell expression each accounted for approximately half of the PE-associated LYN increase. IHC localized Lyn protein to Hofbauer macrophages and the apical microvillar SCT membrane in PE placentas. We conclude that placental LYN expression is selectively elevated in early-onset PE and correlates with maternal blood pressure severity. Lyn localization to trophoblasts and placental immune cells suggests potential roles in mediating inflammation and hypoxia-associated signaling in PE pathogenesis.