Preeclampsia is associated with hypertension, small-for-gestational-age babies, and increased cytolytic natural killer (NK) cells. The specific role of cytolytic NK cells in the pathophysiology of preeclampsia has not been clearly defined. We hypothesized that Reduced Uterine Perfusion Pressure (RUPP) stimulates proliferation and cytolytic activation of NK cells, and that reducing NK cells in RUPP would prevent hypertension, intrauterine growth restriction, and inflammation in response to placental ischemia. RUPP was induced on gestation day (GD) 14 in pregnant rats. NK cells were depleted by i.p. administration of anti-asialo GM1 antibody on GDs 15 and 17. Placental and circulating NK cells were quantified via flow cytometry, mean arterial pressure (MAP), fetal weights, and cytokines were measured on GD 19. Total placental NK cells were 7.4±2% of gated cells in normal pregnant (NP; n=10) and 16.5± 3% of gated cells in RUPP (n=10) rats. Furthermore, cytolytic placental NK cells also increased in RUPP. Depletion of NK cells in RUPP (RUPP + anti-ASGM1) significantly improved MAP and fetal weights. MAP was 108± 2 mmHg in NP, 125± 2 mmHg in RUPP, and 112± 2 mmHg in RUPP + anti-ASGM1 (n=12). Fetal weight was 2.32 ± 0.05 in NP, 1.8± 0.04g in RUPP, and increased to 2.0± 0.04g in RUPP + anti-ASGM1. Placental interferon-γ (IFN-γ) was 40.4± 5.2 pg/mg in NP, 72.17± 3.2 pg/mg in RUPP, and 44.0± 6.5 pg/mg in RUPP + anti-ASGM1 (P<0.05). Placental tumor necrosis factor-α (TNF-α) was 17.9± 1.7 pg/mg in NP, 23.9± 2.2 pg/mg in RUPP, and 12.9± 2.3 pg/mg in RUPP + anti-ASGM1 (P<0.05). Depletion of NK cells significantly lowered MAP, intrauterine growth restriction, and inflammation in RUPP rats indicating that cytolytic NK cells are important in preeclampsia pathophysiology.

Previous studies have demonstrated that T-helper 17 (T17) cells and cytolytic natural killer (cNK) cells are increased in women with preeclampsia. In this study we investigated the role of placental ischemia-stimulated T17 cells in induction of cNK cells in pregnancy. We further assessed the role of T17 cell-mediated oxidative stress in facilitation of cNK cell activation in pregnancy by treating rats with the SOD mimetic tempol. CD4/CD25 cells were isolated from reduced uterine perfusion pressure (RUPP) rats and differentiated into T17 cells in vitro. On day 12 of gestation ( GD12), 1 × 10 placental ischemia-stimulated T17 cells were injected into normal pregnant (NP) rats (NP + RUPP T17 rats), and a subset of rats were treated with tempol (30 mg·kg·day) from GD12 to GD19 (NP + RUPP T17 + tempol rats). On GD19, cNK cells, mean arterial pressure, fetal weight, and cNK cell-associated cytokines and proteins were measured. Placental cNK cells were 2.9 ± 1, 14.9 ± 4, and 2.8 ± 1.0% gated in NP, NP + RUPP T17, and NP + RUPP T17 + tempol rats, respectively. Mean arterial pressure increased from 96 ± 5 mmHg in NP rats to 118 ± 2 mmHg in NP + RUPP T17 rats and was 102 ± 3 mmHg in NP + RUPP T17 + tempol rats. Fetal weight was 2.37 ± 0.04, 1.95 ± 0.14, and 2.3 ± 0.05 g in NP, NP + RUPP T17, and NP + RUPP T17 + tempol rats, respectively. Placental IFNγ increased from 1.1 ± 0.6 pg/mg in NP rats to 3.9 ± 0.6 pg/mg in NP + RUPP T17 rats. Placental perforin increased from 0.18 ± 0.18 pg/mg in NP rats to 2.4 ± 0.6 pg/mg in NP + RUPP T17 rats. Placental levels of granzymes A and B followed a similar pattern. Treatment with tempol did not lower placental cNK cytokines or proteins. The results of the present study identify T17 cells as a mediator of aberrant NK cell activation that is associated with preeclampsia.

Similar to patients enrolled later in the intensive care unit, PS-expressing PMPs are lower in emergency department sepsis non-survivors. These changes primarily reflect the degree of thrombocytopenia, and an independent prognostic role was not observed. Future studies should control for platelet count in assessment of PMP prognosis in sepsis.