Placental endothelial ferroptosis induced by neutrophil NETosis leads to intrauterine growth restriction in dengue virus infection

Studies on dengue virus (DENV) infection during pregnancy show that symptomatic dengue is associated with adverse fetal outcomes, but the mechanisms remain unclear. Our previous research indicated that neutrophils contribute to intrauterine growth restriction (IUGR) by damaging placental vasculature, yet the molecular mechanisms underlying this microvascular injury remain poorly defined. To address this, this study examined placental microvascular ferroptosis by bulk and single-cell transcriptomic reanalyses, immunofluorescence staining, and Western blotting in DENV-2-infected E18.5 placentas from pregnant Ifnar1^−/− C57BL/6J mice (n = 5 per group). Causality was investigated by assessing fetal weight and microvascular damage assessment following administration of ferroptosis inhibitor, neutrophil extracellular trap formation (NETosis) inhibitor, or glutathione supplementation. We observed that ferroptosis in placental vascular endothelial cells was accompanied by vascular disruption and NETosis in our IUGR mouse model. Pharmacological inhibition of ferroptosis alleviated placental injury and restored fetal weight, directly linking ferroptosis to DENV-2-induced IUGR. Moreover, increased 4-hydroxynonenal (4-HNE) levels and decreased glutathione peroxidase 4 (GPX4) levels were detected in the placenta, indicating oxidative stress–driven lipid peroxidation. Glutathione supplementation attenuated ferroptosis and IUGR. Finally, NETosis inhibition reduced placental lipid peroxidation and vascular injury, suggesting that excessive NETosis initially triggers oxidative stress. Taken together, our data suggest that ferroptosis in vascular endothelial cells induced by neutrophil NETosis is the driving cause of IUGR in DENV infections. This study reveals the mechanism underlying DENV-associated adverse pregnancy outcomes and provides potential therapeutic insights.