IL-17-mediated oxidative stress is an important stimulator of AT1-AA and hypertension during pregnancy

Abstract

Preeclampsia is associated with autoimmune cells T(H)17, secreting interleukin-17, autoantibodies activating the angiotensin II type I receptor (AT1-AA), and placental oxidative stress (ROS). The objective of our study was to determine whether chronic IL-17 increases blood pressure by stimulating ROS and AT1-AAs during pregnancy. To answer this question four groups of rats were examined: normal pregnant (NP, n = 20), NP+IL-17 (n = 12), NP+tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl) (n = 7) (a superoxide dismutase mimetic that scavenges ROS), and NP+IL-17+tempol (n = 11). IL-17 (150 pg/day) was infused into NP rats while tempol was administered via the drinking water ad libitum. On day 19 blood pressure (MAP) was recorded, and plasma, urine, and tissue were collected for isolation of ROS detected by chemilluminescent technique. Urinary isoprostane was measured by ELISA. AT1-AAs were determined via cardiomyocyte assay and expressed as beats per minute. MAP increased from 98 ± 3 mmHg in NP to 123 ± 3 mmHg in IL-17-infused NP rats. Urinary isoprostane increased from 1,029 ± 1 in NP to 3,526 ± 2 pg·mg(-1)·day(-1) in IL-17-infused rats (P < 0.05). Placental ROS was 436 ± 4 RLU·ml(-1)·min(-1) (n = 4) in NP and 702 ± 5 (n = 5) RLU·ml(-1)·min(-1) in IL-17-treated rats. Importantly, AT1-AA increased from 0.41 ± 0.05 beats/min in NP rats (n = 8) to 18.4 ± 1 beats/min in IL-17 rats (n = 12). Administration of tempol attenuated the hypertension (101 ± 3 mmHg) ROS (459 ± 5 RLU·ml(-1)·min(-1)) and blunted AT1-AAs (7.3 ± 0.6 beats/min) in NP+IL-17+tempol-treated rats. Additionally, AT1 receptor blockade inhibited IL-17-induced hypertension and placental oxidative stress. MAP was 105 ± 5 mmHg and ROS was 418 ± 5 RLU·ml(-1)·min(-1) in NP+IL 17-treated with losartan. These data indicate that IL-17 causes placental oxidative stress, which serves as stimulus modulating AT1-AAs that may play an important role in mediating IL-17-induced hypertension during pregnancy.

Fig. 1.

IL-17-induced hypertension is attenuated with a superoxide dismutase (SOD) mimetic (tempol) or AT1 receptor blockade. Chronic infusion of IL-17 into normal pregnant (NP) rats causes hypertension during pregnancy. This blood pressure (MAP) response is attenuated by administration of a SOD mimetic or losartan, an At1 receptor blocker. Data are expressed as means ± SE. ***P < 0.05 vs. NP controls.

Fig. 2.

Infusion of IL-17 into NP rats increased circulating CD4+/RORγ+T cells compared with NP control rats. Data are expressed as means ± SE. **P < 0.05 vs. NP controls.

Fig. 3.

IL-17 infusion increases urinary isoprostane excretion. Urinary isoprostane excretion is increased in response to chronic IL-17 infusion, indicating that IL-17 increases oxidative stress. Data are expressed as means ± SE. *P < 0.05 vs. NP controls.

Fig. 4.

IL-17-infused placental oxidative stress is blunted by a SOD mimetic (tempol) or losartan. A: chronic infusion of IL-17 into NP rats significantly produces greater NADPH-stimulated placental reactive oxygen species (ROS). B: chronic administration of tempol to IL-17-infused rats decreases NADPH-stimulated placental oxidative stress to levels no longer significantly different from that of tempol-treated controls. C: chronic AT1 receptor blockade with losartan significantly decreased NADPH-stimulated placental oxidative stress IL-17-treated rats. Data are expressed as means ± SE. RLU, relative light units. ***P < 0.05 vs. NP controls.

Fig. 5.

Tempol administration decreases AT1-AA in response to chronic infusion of IL-17. AT1-AA isolated from serum of rats chronically infused with IL-17 is significantly increased compared with NP rats but is blunted in response to tempol administration. Data are expressed as means ± SE. ***P < 0.001 vs. IL-17-infused rats.