Abstract P213: Placental Ischemia-Stimulated Natural Killer Cells Contribute To Hypertension, Vascular Dysfunction, And Intrauterine Growth Restriction In Pregnant Rats

Abstract

The Reduced Uterine Perfusion Pressure (RUPP) rat model of placental ischemia mimics many characteristics of preeclampsia (PE) such as hypertension (HTN), intrauterine growth restriction (IUGR), and increased cytolytic natural killer cells (cNKs). We have previously shown that natural killer (NK) cell depletion in RUPP rats improves PE pathophysiology and that RUPP NKs have a 5-fold increase in cytotoxicity vs normal pregnant NKs. In this study, we tested the hypotheses that (1) RUPP stimulated NKs play a direct role in causing HTN and IUGR in pregnant rats and (2) normal pregnant control (Sham) NKs attenuate HTN and IUGR in RUPP rats. NKs were isolated from the placentas of Sham and RUPP rats on gestation day (GD) 19. On GD14, vehicle or 5x10 6 RUPP NKs were infused i.v. into a subset of Sham rats, and vehicle or 5x10 6 Sham NKs were infused i.v. into a subset of RUPP rats. On GD18, Uterine Artery Resistance Index (UARI) was measured via Doppler Ultrasound; GD19, cNKs were quantified via flow cytometry and MAP, fetal weight, and blood were acquired. Plasma VEGF and sFlt-1 were measured via ELISA. Placental cNKs (% gated) increased from 3±1% in Sham to 19±5% in RUPP and 21±4% in Sham+RUPP NK (p<0.05 vs Sham), and decreased to 3±1% in RUPP+Sham NK (p<0.05 vs RUPP). Circulating cNKs also followed this trend. MAP increased from 102±1 mmHg in Sham to 130±2 mmHg in RUPP and 121±2 mmHg in Sham+RUPP NK (p<0.05 vs Sham), and was blunted to 113±1 mmHg in RUPP+Sham NK (p<0.05 vs RUPP). Fetal weight decreased from 2.4±0.04 g in Sham to 2.1±0.07 g in RUPP and 2.1±0.03 g in Sham+RUPP NK (p<0.05 vs Sham), and this was normalized to 2.3±0.03 g in RUPP+Sham NK (p<0.05 vs RUPP). UARI increased from 0.56±0.05 in Sham to 0.75±0.06 in RUPP and 0.76±0.05 in Sham+RUPP NK (p<0.05 vs Sham), and decreased to 0.64±0.05 in RUPP+Sham NK (p<0.05 vs RUPP). Circulating sFlt-1 increased from 76±15 pg/mL in Sham to 1391±424 pg/mL in RUPP (p<0.05 vs Sham), 780±256 pg/mL in Sham+RUPP NK, and decreased to 67±8 pg/mL in RUPP+Sham NK (p<0.05 vs RUPP). Furthermore, circulating VEGF decreased in RUPP and Sham+RUPP NK compared to Sham (p<0.05), and increased in RUPP+Sham NK (p<0.05 vs RUPP). These data demonstrate a direct role for cNKs to mediate vascular dysfunction in PE and for normal NKs to promote positive maternal and fetal outcomes.