Preeclampsia (PE) is a hypertensive disorder that occurs after 20 weeks of gestation, implicating the placenta as a key offender. PE is associated with an imbalance among B lymphocytes, CD4 T lymphocytes, NK cells and increased inflammatory cytokines. During early onset PE, trophoblast invasion and placentation are impaired, leading to reduced blood flow to the fetus. In all spectrums of this disorder, a shift towards a pro-inflammatory state where regulatory cells and cytokines are decreased occurs. Specifically, inflammatory CD4 T-cells and inflammatory cytokines are increased while CD4 T regulatory cells (Tregs) and immunosuppressive cytokines such as IL-4 and IL-10 are decreased resulting in B cell activation, production of autoantibodies, endothelial dysfunction and hypertension associated with PE. However, the stimulus for these imbalances is unknown and need to be fully understood so that effective treatments that target the pathogenesis of the disease can be designed. Therefore, this review will focus on the pathways involving CD4 , TH1, TH2, Tregs, TH17s, B cells, and NK cells in the pathophysiology of PE.
Preeclampsia (PE) is new onset hypertension during pregnancy associated with increased uterine artery resistance (UARI) and an imbalance among CD4+ T lymphocytes and natural killer (NK) cells. We have shown an important role for 17-hydroxyprogesterone caproate (17-OHPC) to improve hypertension and fetal demise in the RUPP rat model of PE. However we have not examined a role for 17-OHPC to improve NK cells and CD4 + TH2 cells as possible mechanisms for improved fetal weight and hypertension. Therefore, we hypothesized that 17-OHPC lowers NK cells while improving the T cell ratio in the RUPP rat. RUPP was surgically induced on gestational day 14 in pregnant rats. 17-OHPC (3.32mg/kg) was administered intraperitoneal on day 15, UARI was measured on day 18. Blood pressure (MAP), blood and tissues were collected on GD 19. MAP in NP rats (n=9) was 100 ± 2, 104±6 in Sham rats (n=8), 128 ± 2 in RUPP (n=11) and 115±3 mmHg in RUPP+17-OHPC (n=10), p <0.05. Pup weight and UARI were improved after 17-OHPC. Total and cytolytic placental NK cells were 38 ±5, and 12 ±2% gate in RUPP rats which decreased to 1.6 ± 0.5 and 0.4 ± 0.2 % gate in RUPP+17OHPC rats. CD4 + T cells were 40±3 in RUPP rats, which significantly decreased to 7±1 RUPP+17-OHPC rats. Circulating and placental TH2 cells were 6.0 ± 1, 0.3±0.1% gate in RUPP rats and 12±1 %, 2±0.5% gate in RUPP+17-OHPC rats, p <0.05 This study identifies new mechanisms whereby 17-OHPC improves outcomes in response to placental ischemia.
Preeclampsia (PE) is characterized by chronic inflammation and elevated agonistic autoantibodies to the angiotensin type 1 receptor (AT1-AA), endothelin-1, and uterine artery resistance index (UARI) during pregnancy. Previous studies report an imbalance among immune cells, with T-helper type 2 (Th2) cells being decreased during PE. We hypothesized that interleukin-4 (IL-4) would increase Th2 cells and improve the pathophysiology in response to placental ischemia during pregnancy. IL-4 (600 ng/day) was administered via osmotic minipump on gestational day 14 to normal pregnant (NP) and reduced uterine perfusion pressure (RUPP) rats. Carotid catheters were inserted, and Doppler ultrasound was performed on gestational day 18. Blood pressure (mean arterial pressure), TNF-α, IL-6, AT1-AA, natural killer cells, Th2 cells, and B cells were measured on gestational day 19. Mean arterial pressure was 97 ± 2 mmHg in NP ( n = 9), 101 ± 3 mmHg in IL-4-treated NP ( n = 14), and 137 ± 4 mmHg in RUPP ( n = 8) rats and improved to 108 ± 3 mmHg in IL-4-treated RUPP rats ( n = 17) ( P < 0.05). UARI was 0.5 ± 0.03 in NP and 0.8 in RUPP rats and normalized to 0.5 in IL-4-treated RUPP rats ( P < 0.05). Plasma nitrate-nitrite levels increased in IL-4-treated RUPP rats, while placental preproendothelin-1 expression, plasma TNF-α and IL-6, and AT1-AA decreased in IL-4-treated RUPP rats compared with untreated RUPP rats ( P < 0.05). Circulating B cells and placental cytolytic natural killer cells decreased after IL-4 administration, while Th2 cells increased in IL-4-treated RUPP compared with untreated RUPP rats. This study illustrates that IL-4 decreased inflammation and improved Th2 numbers in RUPP rats and, ultimately, improved hypertension in response to placental ischemia during pregnancy.
Preeclampsia (PE) is characterized by new onset hypertension in association with elevated natural killer (NK) cells and inflammatory cytokines which are likely culprits for decreased fetal weight during PE pregnancies. As progesterone increases during normal pregnancy, it stimulates Progesterone Induced Blocking Factor (PIBF). PIBF has been shown to decrease inflammation and cytolytic NK cells, both of whichare increased during PE. We hypothesized that PIBF reduces inflammation as a mechanism to improve hypertension in the preclinical RUPP rat model of PE. PIBF (2.0 µg/mL) was administered intraperitoneally on gestational day 15 to either RUPP or normal pregnant (NP) rats. On day 18 carotid catheters were inserted. Mean arterial blood pressure (MAP) and samples were collected on day 19. MAP in NP rats (n=11) was 100±2 mmHg and 105±3 in NP+PIBF (n=8), 122±1 in RUPP rats (n=10), which improved to 110±2 mmHg in RUPP+PIBF rats (n=11), p<0.05. Pup weight was 2.4±0.1 grams (g) in NP, 2.5±0.1 g in NP+PIBF, 1.9±0.1 g in RUPP and improved to 2.1±0.1gin RUPP+PIBF rats. Circulating and placental cytolytic NK cells, IL-17 and IL-6 were significantly reduced while IL-4 and TH2 cells were significantly increased in RUPP rats after PIBF administration. Importantly, vasoactive pathways preproendothelin-1, nitric oxide and sFlt-1 were normalized in RUPP+PIBF rats compared to RUPP rats, p<0.05. Our findings suggest that PIBF normalized IL-4/TH2 cells which was associated with improved inflammation, fetal growth restriction and blood pressure in the RUPP rat model of PE.
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