GSK484 attenuates placental endothelial injury and improves gestation outcome in rats with preeclampsia by inhibiting PAD4-mediated neutrophil extracellular traps formation.

Preeclampsia (PE) is a serious pregnancy disorder, but its pathogenesis has not been well elucidated and has no effective pharmacological therapy. Here we investigated the potential protective effect of GSK484, a selective inhibitor of peptidyl arginine deiminase 4 (PAD4), on PE in rats and the underlying mechanisms. PE was induced in pregnant rats by intravenous injection of low-dose lipopolysaccharides (LPS), and the general manifestations of PE were examined. The effects of GSK484 on placental expressions of PAD4 and vascular endothelial growth factor A (VEGFA), formation of neutrophil extracellular traps (NETs), placental neutrophil infiltration, and endothelial and microvasculature injury were measured using serial technologies including histology, ELISA, RT-qPCR, western blotting, immunofluorescent and immunohistochemical staining. Results show that LPS-treated pregnant rats exhibited PE-like symptoms and molecular pathologies, including late-onset hypertension, proteinuria, placental microvasculature and kidney injuries, growth restriction of the offspring, elevations of placental and circulatory PAD4, and formation of NETs which were composed of double-stranded DNA (dsDNA), myeloperoxidase (MPO) and citrullinated histone 3 (Cit H3) released from activated neutrophils. Administration of GSK484 (a PAD4 inhibitor) (2 mg/kg, i. p.) to pregnant rats reduced circulatory soluble fms-like tyrosine kinase 1 (sFlt-1), placental PAD4 expression and NETs formation, increased placental VEGFA expression and microvessel density (MVD), decreased blood pressure and urine proteins, and improved maternal body weight gain and offspring growth restriction. We conclude that GSK484 exerts a protective effect on rat PE mainly via inhibiting PAD4-mediated placental NETs formation, and ultimately improves maternal placental microvascular injury and benefits the pregnancy outcomes including mother and offspring. The study suggests that GSK484 may have the potential to be an effective drug in the treatment of PE.