Abstract P260: Placental Ischemia-stimulated TH17 Cells Induce Preeclampsia-associated Cytolytic Natural Killer Cells During Pregnancy

Abstract

Preeclampsia (PE), a hypertensive disorder of pregnancy, is associated with increased circulating T H 17 cells (T H 17s), IL-17 and cytolytic Natural Killer cells (cNKs). Although the stimulus for cNKs in PE is currently unknown, recent in vitro studies suggest that IL-17 induces proliferation and cytotoxic activity in human NK cells. We have previously demonstrated that placental ischemia (PI)-stimulated T H 17s mediate pathophysiology in pregnant rats similar to that seen in PE. In this study we tested the hypothesis that PI-stimulated T H 17s induce cNKs and their associated cytokines, IFNγ and TNFα, and cytolytic proteins, perforin and granzyme B. T H 17s were injected i.p. into NP rats on gestation day (GD) 12. Total NK cells (tNKs) and cNKs in blood and placental lymphocytes were quantified via flow cytometry. MAP, pup and placental weight, tissue ROS, cytokines, perforin and granzyme B were measured. As previously shown circulating T H 17s and IL-17, MAP, IUGR, and placental and renal ROS were significantly increased after T H 17 adoptive transfer. MAP was 100.6±1.7 mmHg (n=7) in NP rats and 119.4±2.6 mmHg (n=7) in NP recipients of T H 17s (NP+T H 17, p< 0.05). Placental tNKs (% gated) were significantly increased in NP+T H 17 (19.7±4.6%) compared to NP rats (5.4±2.0%; p< 0.05). Importantly, placental cNKs were significantly increased in response to T H 17s (NP: 2.9±0.9% vs NP+T H 17: 14.9 ±4.0%, p< 0.05). Serum and placental IFNγ significantly increased from 5.8±3.3 pg/mL and 1.1±0.6 pg/mL/mg, respectively in NP to 193±26.12 pg/mL and 3.9±0.6 pg/mL/mg in NP+T H 17 (p< 0.05). Serum and placental TNFα increased from 0.9 pg/mL and 0.1 pg/mL/mg in NP to 4.5 pg/mL and 0.2 pg/mL/mg in NP+T H 17 (p< 0.05). Placental perforin was significantly increased from 0.3 pg/mL/mg in NP to 1.6 pg/mL/mg in NP+T H 17 (p< 0.05). Serum perforin, and serum and placental granzyme B were comparable between NP vs NP+T H 17. These data suggest a role for PI-stimulated T H 17s to induce a cytotoxic phenotype in NKs during pregnancy and identifies stimulation of cNKs as a new mechanism by which the T H 17/IL-17 pathway may mediate pathophysiology during PE. Further investigation into this innovative pathway may identify novel targets with therapeutic potential to improve outcomes associated with PE.