B2 cells contribute to hypertension and natural killer cell activation possibly via AT1-AA in response to placental ischemia.

Preeclampsia, new onset hypertension during pregnancy, is associated with activated T helper cells (Th) and B cells secreting agonistic autoantibodies against the angiotensin II type 1 receptor (AT1-AA). The reduced uterine perfusion pressure (RUPP) model of placental ischemia recapitulates these characteristics. We have shown that Th-B cell communication contributes to AT1-AA and symptoms of preeclampsia in the RUPP rat. B2 cells are classical B cells that communicate with Th cells and are then transformed into memory B cells. We hypothesize that B2 cells cause hypertension, natural killer (NK) cell activation, and complement activation during pregnancy through the production of AT1-AA. To test this hypothesis, total splenic B cells and B2 cells were isolated from normal pregnant (NP) or RUPP rats on gestational day (GD)19 and adoptively transferred into GD12 NP rats. A group of recipient rats was treated with a specific inhibitor peptide of AT1-AA. On GD19, mean arterial pressure was measured, tissues were collected, activated NK cells were measured by flow cytometry, and AT1-AA was measured by cardiomyocyte assay. NP recipients of RUPP B cells or RUPP B2 cells had increased mean arterial pressure, AT1-AA, and circulating activated NK cells compared with recipients of NP B cells. Hypertension in NP recipients of RUPP B cells or RUPP B2 was attenuated with AT1-AA blockade. This study demonstrates that B cells and B2 cells from RUPP rats cause hypertension and increased AT1-AA and NK cell activation in response to placental ischemia during pregnancy.NEW & NOTEWORTHY This study demonstrates that placental ischemia-stimulated B2 cells induce hypertension and circulating natural killer cell activation and angiotensin II type 1 receptor production in normal pregnant rats.

CD4+ T cells cause renal and placental mitochondrial oxidative stress as mechanisms of hypertension in response to placental ischemia.

The reduced uterine perfusion pressure (RUPP) rat model and normal pregnant (NP) rat recipients of RUPP CD4+ T cells recapitulate many characteristics of preeclampsia such as hypertension and oxidative stress. We have shown an important hypertensive role for natural killer (NK) cells to cause mitochondrial dysfunction in RUPP rats; however, the role for RUPP CD4+ T cells to stimulate NK cells is unknown. Therefore, we hypothesized that RUPP-induced CD4+ T cells activate NK cells to cause mitochondrial dysfunction/reactive oxygen species (ROS) as mechanisms of hypertension during pregnancy. We tested our hypothesis by adoptive transfer of RUPP CD4+ T cells into NP rats or by inhibiting the activation of RUPP CD4+ T cells with Orencia (abatacept) and examining hypertension, NK cells, and mitochondrial function. RUPP was performed on gestation day (GD) 14, and splenic CD4+ T cells were isolated on GD 19 and injected into NP rats on GD 13. In a separate group of rats, Orencia was infused and the RUPP procedure was performed. Mean arterial pressure and placental and renal mitochondrial ROS increased in RUPP (n = 7, P < 0.05) and NP + RUPP CD4+ T-cell recipients (n = 13, P < 0.05) compared with control NP (n = 7) and NP + NP CD4+ T-cell recipients (n = 5) but was reduced with Orencia (n = 13, P < 0.05). Placental and renal respiration was reduced in RUPP (n = 6, P < 0.05) and NP + RUPP CD4+ T-cell recipients (n = 6, state 3 P < 0.05) compared with NP (n = 5) and NP + NP CD4+ T-cell recipients (n = 5) but improved with Orencia (n = 9, n = 8 P < 0.05). These data indicate that CD4+ T cells, independent of NK cells, cause mitochondrial dysfunction/ROS contributing to hypertension in response to placental ischemia during pregnancy.

A Neonatal Rodent Model of Retroorbital Vein Injection.

Intravenous (iv) injection is the most used route of drug administration in neonates in the clinical setting. Therefore, retroorbital vein injection is an important method for compound administration in research, where successful proof-of-concept studies can progress into much-needed neonatal clinical trials. Most intravenous studies in neonatal rodents use the superficial temporal/facial vein. However, retroorbital injection becomes unreliable in neonatal rodents older than 2 days after the skin darkens and the vein is no longer visible. In the present protocol, we describe the retroorbital injection of the venous sinus in both the neonatal mouse and rat at ages when the superficial temporal vein is no longer visible, but the eyes have not opened yet. Eye-opening facilitates retro-orbital injection by enabling the researcher to clearly see that they are not perforating the eye when inserting the needle. We demonstrate that this technique can be performed in a reliable and reproducible manner without adverse effects. Additionally, we show that it can be used in many studies, such as administering compounds to study neonatal brain injury.

Hypertension and Cognitive Dysfunction in a Pregnant Rat Model of PE; a Role for CD4+ T Cells.

OBJECTIVE: Preeclampsia (PE) is associated with hypertension (HTN) during pregnancy and activated CD4+ T cells, inflammatory cytokines, and autoantibodies to the angiotensin II type I receptor (AT1-AA). Having had COVID-19 (CV) during pregnancy is associated with an increased incidence of a PE-like phenotype. Both PE and CV have long-lasting neurological implications and studies show that nonpregnant COVID patients produce AT1-AA. We have shown that CD4+ T cells from PE women cause a PE phenotype in nude athymic rats. In this study, we sought to examine the role of CD4+ T cells from PE with a CV History (Hx) to contribute to a PE phenotype and to determine the importance of CD4+ T cells in cognitive dysfunction during pregnancy. METHODS: At delivery, blood and placentas were collected, and one million placental CD4+ T cells from each PE and each normotensive patient, with (NT) or without (NP) a CV (Hx) during pregnancy, were isolated, purified, and injected i.p. into a gestational day (GD) 12 pregnant nude athymic rat (one patient/rat). At GD19, blood pressure (MAP) and circulating factors were assessed in recipient rats. Cognitive function and memory were assessed using Novel Object Recognition and Barnes Maze tests, respectively. Placental ACE-2 activity and AT1-AA were measured from COVID Hx patients. A one- or two-way ANOVA with Bonferroni's multiple comparisons test was used for statistical analysis. RESULTS: Blood pressure was increased in patients with PE, with or without COVID, compared to NT patients. There were no significant changes in placental ACE activity in patients with COVID Hx with or without PE. AT1-AA was elevated in PE patients and in both PE and NT COVID Hx compared to control NP. In pregnant recipient rats, MAP increased in CV Hx PE (113 ± 2, n = 8) compared to CV Hx NT (101 ± 5, n = 6). PE and PE CV Hx CD4+ T Cell recipient rats exhibited impaired memory and cognitive dysfunction (p < 0.05), compared to control groups. Recipient rats of PE CV Hx CD4+ T cells had elevated AT1-AA compared to NT CV Hx recipients. Both COVID Hx groups and recipients of PE CD4+ T cells had elevated TNF alpha compared to NP. CONCLUSION: Our findings indicate that pregnant patients with a Hx of COVID during pregnancy produce AT1-AA, with or without PE. Recipients of CD4+ T cells from PE with or without a CV Hx during pregnancy cause HTN and elevated AT1-AA. TNF-α is elevated in PE and in CV Hx NT and PE recipients. Interestingly, recipients of T cells from PE patients with or without a Hx of CV had worse cognitive function during pregnancy, compared to recipient rats of NP CD4+ T cells. These data demonstrate the importance of CD4+ T cells in HTN and impaired neurological function during PE in the presence or absence of a prior COVID-19 infection during pregnancy.

AT1-AA Is Produced in Offspring in Response to Placental Ischemia and Is Lowered by B-Cell Depletion Without Compromising Overall Offspring Health.

BACKGROUND: Preeclampsia, new-onset hypertension during pregnancy alongside other organ dysfunction, is the leading cause of mortality for the mother and low birth weight for the baby. Low birth weight contributes to high risk of cardiovascular disorders later in life. Women with preeclampsia have activated B cells producing agonistic autoantibodies to AT1-AA (angiotensin II type I receptor). We hypothesize that rituximab, a B cell-depleting chemotherapeutic, will deplete maternal B cells in reduced uterine perfusion pressure (RUPP) rats without worsening the effect of placental ischemia on pup growth and survival. METHODS AND RESULTS: To test this hypothesis, the RUPP procedure was performed, and rituximab was continuously infused via miniosmotic pump. Maternal blood and tissues were collected. A separate group of dams were allowed to deliver, pup weights were recorded, and at 4 months of age, tissues were collected from offspring. Immune cells were measured via flow cytometry, and AT1-AA was quantified using a contraction bioassay. Blood pressure increased in RUPP rats and was normalized with rituximab treatment. RUPP offspring also had increased circulating B cells, cytolytic natural killer cells, and increased circulating AT1-AA, which were normalized with maternal rituximab treatment. This is the first study to analyze the AT1-AA in RUPP offspring, which was normalized with rituximab. CONCLUSIONS: Our findings indicate that perinatal rituximab lowers maternal mean arterial pressure in RUPP rats and improves birth weight, circulating AT1-AA, and circulating natural killer cells, indicating that rituximab improves adverse fetal outcomes in response to placental ischemia.

Setting a stage: Inflammation during preeclampsia and postpartum.

Preeclampsia (PE) is a leading cause of maternal and fetal mortality worldwide. The immune system plays a critical role in normal pregnancy progression; however, inappropriate inflammatory responses have been consistently linked with PE pathophysiology. This inflammatory phenotype consists of activation of the innate immune system, adaptive immune system, and increased inflammatory mediators in circulation. Moreover, recent studies have shown that the inflammatory profile seen in PE persists into the postpartum period. This manuscript aims to highlight recent advances in research relating to inflammation in PE as well as the inflammation that persists postpartum in women after a PE pregnancy. With the advent of the COVID-19 pandemic, there has been an increase in obstetric disorders associated with COVID-19 infection during pregnancy. This manuscript also aims to shed light on the relationship between COVID-19 infection during pregnancy and the increased incidence of PE in these women.

The role of immune cells and mediators in preeclampsia.

Preeclampsia is a hypertensive disorder of major concern in pregnancy than can lead to intrauterine growth restriction, placental abruption and stillbirth. The pathophysiology of preeclampsia is multifactorial, including not only kidney dysfunction but also endothelial dysfunction, as the maternal endothelium becomes exposed to placental factors that are released into the circulation and increase systemic levels of vasoconstrictors, oxidative stress, anti-angiogenic factors and inflammatory mediators. Importantly, inflammation can lead to insufficient placental perfusion and low birthweight in offspring. Various innate and adaptive immune cells and mediators have been implicated in the development of preeclampsia, in which oxidative stress is associated with activation of the maternal inflammatory response. Immune cells such as regulatory T cells, macrophages, natural killer cells, and neutrophils are known to have major causative roles in the pathology of preeclampsia, but the contributions of additional immune cells such as B cells, inflammatory cytokines and anti-angiotensin II type 1 receptor autoantibodies are also now recognized. Immunological interventions, therefore, have therapeutic potential in this disease. Here, we provide an overview of the immune responses that are involved in the pathogenesis of preeclampsia, including the role of innate and adaptive immune cells and mediators.

AT1-AA Infusion during Pregnancy Impairs CBF Autoregulation Postpartum.

Preeclampsia (PE), new-onset hypertension during pregnancy alongside organ dysfunction, is a leading cause of morbidity and mortality for the mother and fetus. PE women have activated B cells that produce agonistic autoantibodies to the angiotensin II type 1 receptor (AT1-AA). AT1-AA impairs cerebral blood flow (CBF) autoregulation during pregnancy. Although AT1-AA often remains elevated up to 8 years postpartum, AT1-AA's effect on CBF autoregulation postpartum is unknown. This study examined whether elevated AT1-AA during pregnancy impairs CBF autoregulation postpartum and if this was augmented by infusion of AT1-AA postpartum. AT1-AA was infused into 12-week-old timed-pregnant Sprague Dawley rats beginning on gestational day 14. Uterine artery resistance index (UARI) was measured on gestational day 18 as a measure of endothelial dysfunction associated with PE. Dams were allowed to deliver. One group was given a second infusion of AT1-AA (50% perinatal dose mimicking levels observed in postpartum PE women) at 9 weeks postpartum. After postpartum week 10, mean arterial pressure (MAP) was measured in conscious rats and CBF autoregulation was measured by laser Doppler flowmetry. AT1-AA during pregnancy increased UARI (P<0.05). AT1-AA during pregnancy did not affect MAP postpartum but did impair CBF autoregulation postpartum. Infusion of AT1-AA postpartum significantly elevated blood pressure (P<0.01) but did not further impair CBF autoregulation. This study demonstrates that circulating AT1-AA during pregnancy causes impairment of CBF autoregulation well into the postpartum period indicating that elevated AT1-AA leads to long-term cerebrovascular consequences. Targeting AT1-AA may prevent cerebrovascular effects associated with PE during pregnancy and postpartum.

Inhibition of angiotensin II type 1 receptor agonistic autoantibodies by direct binding does not impact reduced uterine perfusion pressure offspring birthweight and blood pressure at adulthood.

BACKGROUND: Preeclampsia, a new-onset hypertension with end-organ damage in pregnancy, is associated with maternal death and morbidity, low birthweight, and B cells producing agonistic autoantibodies to the angiotensin II type 1 receptor. Angiotensin II type 1 receptor agonistic autoantibodies are produced during pregnancy and after delivery and are in the fetal circulation of women with preeclampsia. Angiotensin II type 1 receptor agonistic autoantibodies are shown to contribute to endothelial dysfunction, renal dysfunction, hypertension, fetal growth restriction, and chronic inflammation in women with preeclampsia. The reduced uterine perfusion pressure rat model of preeclampsia exhibits these features. In addition, we have shown that the administration of a 'n7AAc', which blocks the actions of the angiotensin II type 1 receptor autoantibodies, improves preeclamptic features in the rat with reduced uterine perfusion pressure. However, the effect of a 'n7AAc' on the long-term health of the offspring of rats with reduced uterine perfusion pressure is unknown. OBJECTIVE: This study aimed to test the hypothesis that inhibition of angiotensin II type 1 receptor autoantibodies during pregnancy will improve offspring birthweight and prevent increased cardiovascular risk in offspring in adulthood. STUDY DESIGN: To test our hypothesis, a 'n7AAc' (24 µg/d) or vehicle (saline) was given on gestation day 14 via miniosmotic pumps to sham-operated (sham) and Sprague-Dawley rat dams with reduced uterine perfusion pressure. Dams were allowed to deliver naturally, and pup weights were recorded within 12 hours after birth. Pups were aged to 16 weeks, at which time mean arterial pressure was measured and whole blood was collected to measure immune cells by flow cytometry, cytokines by enzyme-linked immunosorbent assay, and angiotensin II type 1 receptor autoantibodies by bioassay. A 2-way analysis of variance with the Bonferroni multiple comparison posthoc test was used for statistical analysis. RESULTS: There was no significant change in offspring birthweight of 'n7AAc'-treated male (5.63±0.09 g) or female (5.66±0.14 g) offspring from reduced uterine perfusion pressure dams compared with vehicle male (5.51±0.17 g) or female (5.74±0.13 g) offspring from reduced uterine perfusion pressure dams. In addition, 'n7AAc' treatment did not affect the birthweight of sham male (5.83±0.11 g) or female (5.64±0.12) offspring compared with vehicle sham male (5.811±0.15 g) or female (5.40±0.24 g) offspring. At adulthood, mean arterial pressure was unchanged in 'n7AAc' treated-male (133±2 mm Hg) and female (127±3 mm Hg) offspring from reduced uterine perfusion pressure dams compared with vehicle male (142±3 mm Hg) and female (133±5 mm Hg) offspring from reduced uterine perfusion pressure dams, the 'n7AAc'-treated sham male (133±3 mm Hg) and female (135±3 mm Hg) offspring, and vehicle sham male (138±4 mm Hg) and female (130±5 mm Hg) offspring. The circulating angiotensin II type 1 receptor autoantibodies were increased in vehicle male (10±2 ΔBPM) and female (14±2 ΔBPM) offspring from reduced uterine perfusion pressure dams and 'n7AAc'-treated male (11±2 ΔBPM) and female (11±2 ΔBPM) offspring from reduced uterine perfusion pressure dams compared with vehicle sham male (1±1 ΔBPM) and female (-1±1 ΔBPM) offspring and 'n7AAc'-treated sham male (-2±2 ΔBPM) and female (-2±2 ΔBPM) offspring. CONCLUSION: Our findings indicated that perinatal 7-amino acid sequence peptide treatment does not negatively impact offspring survival or weight at birth. Perinatal 'n7AAc' treatment did not prevent increased cardiovascular risk in offspring, but it also did not cause an increased cardiovascular risk in offspring with reduced uterine perfusion pressure compared with controls. Furthermore, perinatal 'n7AAc' treatment did not affect endogenous immunologic programming as observed by no change in circulating angiotensin II type 1 receptor autoantibodies in either sex of adult offspring from reduced uterine perfusion pressure dams.

Inhibiting B cell activating factor attenuates preeclamptic symptoms in placental ischemic rats.

PROBLEM: Preeclampsia (PE), new-onset hypertension during pregnancy, is associated with a pro-inflammatory state with activated T cells, cytolytic natural killer (NK) cells, dysregulated complement proteins, and B cells secreting agonistic autoantibodies to the angiotensin II type-1 receptor (AT1-AA). The reduced uterine perfusion pressure (RUPP) model of placental ischemia recapitulates these features of PE. Blocking CD40L-CD40 communication between T and B cells or B cell depletion with Rituximab prevents hypertension and AT1-AA production in RUPP rats. This suggests that T cell-dependent B cell activation contributes to the hypertension and AT1-AA associated with PE. B2 cells maturing into antibody producing plasma cells are the product of T cell-dependent B cell-interactions and B cell Activating Factor (BAFF) is an integral cytokine in the development of B2 cells specifically. Thus, we hypothesize that BAFF blockade will selectively deplete B2 cells, therefore reducing blood pressure, AT1-AA, activated NK Cells, and complement in the RUPP rat model of PE. METHOD OF STUDY: Gestational Day (GD) 14 pregnant rats underwent the RUPP procedure, and a subset were treated with 1 mg/kg Anti-BAFF antibodies via jugular catheters. On GD19, blood pressure was measured, B cells and NK cells were measured by flow cytometry, AT1-AA was measured by cardiomyocyte bioassay, and complement activation was measured by ELISA. RESULTS: Anti-BAFF therapy attenuated hypertension, AT1-AA, NK cell activation, and APRIL levels in RUPP rats without negatively impacting fetal outcomes. CONCLUSIONS: This study demonstrates that B2 cells contribute to hypertension, AT1-AA, and NK cell activation in response to placental ischemia during pregnancy.

RUPP Th17s cause hypertension and mitochondrial dysfunction in the kidney and placenta during pregnancy.

BACKGROUND: Preeclampsia (PE), new-onset hypertension (HTN), and organ dysfunction during the second half of pregnancy, is associated with an increase in inflammatory immune cells, including T helper 17 (Th17) cells. Studies have demonstrated that mitochondrial (mt) dysfunction is important in the pathogenesis of PE though causative factors have yet to be fully identified. Although Th17 cells, natural killer (NK) cells, and mt dysfunction contribute to HTN in the reduced uterine perfusion pressure (RUPP) rat model, the role of Th17 cells or IL-17 in mt dysfunction is unknown. Therefore, we hypothesize that RUPP stimulated Th17 cells cause HTN and mt dysfunction, which is alleviated with the blockade of IL-17. METHODS: On gestational day 12 (GD12), RUPP Th17 cells were transferred into normal pregnant (NP) Sprague Dawley rats. A subset of NP + RUPPTh17 rats received IL-17RC (100 pg/day) on GD14-19. Blood pressure (MAP), NK cells, and mt function were measured on GD19 in all groups. RESULTS: MAP increased in response to NP + RUPP Th17 compared to NP rats and was lowered with IL-17RC. Circulating and placental NK cells increased with NP + RUPP Th17 compared to NP and were lowered with IL-17RC. Renal mtROS increased in NP + RUPP Th17 compared to NP and was normalized with IL-17RC. Similar to PE women, placental mtROS decreased in NP + RUPP Th17 and was normalized with IL-17RC. CONCLUSION: Our results indicate that IL-17RC inhibition normalizes HTN, NK cell activation, and multi-organ mt dysfunction caused by Th17 cells stimulated in response to placental ischemia.

The Role of Different Lymphoid Cell Populations in Preeclampsia Pathophysiology.

Preeclampsia (PE), new-onset hypertension during pregnancy, affects up to 10% of pregnancies worldwide. Despite being the leading cause of maternal and fetal morbidity and mortality, PE has no cure beyond the delivery of the fetal-placental unit. Although the exact pathogenesis of PE is unclear, there is a strong correlation between chronic immune activation; intrauterine growth restriction; uterine artery resistance; dysregulation of the renin-angiotensin system. Which contributes to renal dysfunction; and the resulting hypertension during pregnancy. The genesis of PE is thought to begin with insufficient trophoblast invasion leading to reduced spiral artery remodeling, resulting in decreased placental perfusion and thereby causing placental ischemia. The ischemic placenta releases factors that shower the endothelium and contribute to peripheral vasoconstriction and chronic immune activation and oxidative stress. Studies have shown imbalances in proinflammatory and anti-inflammatory cell types in women with PE and in animal models used to examine mediators of a PE phenotype during pregnancy. T cells, B cells, and natural killer cells have all emerged as potential mediators contributing to the production of vasoactive factors, renal and endothelial dysfunction, mitochondrial dysfunction, and hypertension during pregnancy. The chronic immune activation seen in PE leads to a higher risk for other diseases, such as cardiovascular disease, CKD, dementia during the postpartum period, and PE during a subsequent pregnancy. The purpose of this review is to highlight studies demonstrating the role that different lymphoid cell populations play in the pathophysiology of PE. Moreover, we will discuss treatments focused on restoring immune balance or targeting specific immune mediators that may be potential strategies to improve maternal and fetal outcomes associated with PE.

Placental CD4+ T cells from preeclamptic patients cause autoantibodies to the angiotensin II type I receptor and hypertension in a pregnant rat model of preeclampsia.

Preeclampsia (PE) is a hypertensive disorder of pregnancy associated with activated CD4+ T cells and autoantibodies to angiotensin II type 1 receptor (AT1-AA). We have previously shown that CD4+ T cells isolated from women with PE cause hypertension, increased tumor necrosis factor alpha (TNF-α), endothelin-1, and soluble fms-like tyrosine kinase-1 (sFlt-1) when injected into pregnant nude-athymic rats compared to CD4+ T cells from normal pregnant (NP) women. However, the role of PE CD4+ T cells to cause AT1-AA as a mechanism of hypertension is not known. Aim: Our goal was to determine if PE CD4+ T cells stimulate AT1-AA in pregnant nude-athymic rats. CD4+ T cells were isolated from human NP and PE placentasand injected into nude-athymic rats on gestational day (GD) 12. In order to examine the role of the PE CD4+ T cells to stimulate B cell secretion of AT1-AA, a subset of the rats receiving PE CD4+ T cells were treated with rituximab on GD 14 or anti-CD40 ligand (anti-CD40L) on GD 12. On GD 19, mean arterial pressure (MAP) and tissues were obtained MAP [114 ± 1 mmHg (n = 9)] and AT1-AA [19.8 ± 0.9 beats per minute (bpm, n = 4)] were increased in NP nude + PE CD4+ T cells compared to NP nude + NP CD4+ T cells [98 ± 2 mmHg (n = 7, P < 0.05) and 1.3 ± 0.9 bpm (n = 5, P < 0.05)]. Rituximab (103 ± 2 mmHg, n = 3, P < 0.05) and anti-CD40L (102 ± 1 mmHg, n = 3, P < 0.05) lowered MAP compared to NP nude + PE CD4+ T cells. Circulating a proliferation-inducing ligand (APRIL) and placental angiotensin-converting enzyme 2 (ACE-2) activity was increased in response to PE CD4+ T cells. These results show that placental CD4+ T cells play an important role in the pathophysiology of PE, by activating B cells secreting AT1-AA to cause hypertension during pregnancy.

Low Dose of IL-2 Normalizes Hypertension and Mitochondrial Function in the RUPP Rat Model of Placental Ischemia.

IL-2 is a cytokine released from CD4+T cells with dual actions and can either potentiate the inflammatory response or quell a chronic inflammatory response depending on its circulating concentration. IL-2 is elevated in many chronic inflammatory conditions and is increased during preeclampsia (PE). PE is characterized by new-onset hypertension during pregnancy and organ dysfunction and increasing evidence indicates that proinflammatory cytokines cause hypertension and mitochondrial (mt) dysfunction during pregnancy. The reduced uterine perfusion pressure (RUPP) model of placental ischemia is a rat model of PE that we commonly use in our laboratory and we have previously shown that low doses of recombinant IL-2 can decrease blood pressure in RUPP rats. The objective of this study was to determine the effects of a low dose of recombinant IL-2 on multi-organ mt dysfunction in the RUPP rat model of PE. We tested our hypothesis by infusing recombinant IL-2 (0.05 ng/mL) into RUPP rats on GD14 and examined mean arterial pressure (MAP), renal, placental and endothelial cell mt function compared to control RUPP. MAP was elevated in RUPP rats (n = 6) compared to controls (n = 5) (122 ± 5 vs. 102 ± 3 mmHg, p < 0.05), but was reduced by administration of LD recombinant IL-2 (107 ± 1 vs. 122 ± 5 mmHg, n = 9, p < 0.05). Renal, placental and endothelial mt ROS were significantly increased in RUPP rats compared to RUPP+ IL-2 and controls. Placental and renal respiration rates were reduced in RUPP rats compared to control rats but were normalized with IL-2 administration to RUPPs. These data indicate that low-dose IL-2 normalized multi-organ mt function and hypertension in response to placental ischemia.

Progesterone Induced Blocking Factor Reduces Hypertension and Placental Mitochondrial Dysfunction in Response to sFlt-1 during Pregnancy.

Preeclampsia (PE) is characterized by new onset hypertension in association with placental ischemia, reduced fetal weight, elevated soluble fms-like tyrosine kinase-1 (sFlt-1), and placental mitochondrial (mt) dysfunction and oxidative stress (ROS). Progesterone induced blocking factor (PIBF) is a product of progesterone signaling that blocks inflammatory processes and we have previously shown PIBF to lower mean arterial blood pressure (MAP) and sFlt-1 in a rat model of PE. Infusion of sFlt-1 causes hypertension and many characteristics of PE in pregnant rodents, however, its role in causing mt dysfunction is unknown. Therefore, we hypothesize that PIBF will improve mt function and MAP in response to elevated sFlt-1 during pregnancy. We tested our hypothesis by infusing sFlt-1 via miniosmotic pumps in normal pregnant (NP) Sprague-Dawley rats (3.7 µg·kg-1·day-1) on gestation days (GD) 13-19 in the presence or absence of PIBF (2.0 µg/mL) injected intraperitoneally on GD 15 and examined mean arterial blood pressure (MAP) and placental mt ROS on GD 19. sFlt-1 increased MAP to 112 + 2 (n = 11) compared to NP rats (98 + 2 mmHg, n = 15, p < 0.05), which was lowered in the presence of sFlt-1 (100 + 1 mmHg, n = 5, p < 0.05). Placental mtATP was reduced in sFlt-1 infused rats versus NP controls, but was improved with PIBF. Placental mtROS was elevated with sFlt-1 compared to NP controls, but was reduced with PIBF. Sera from NP + sFlt-1 increased endothelial cell mtROS, which was attenuated with PIBF. These data demonstrate sFlt-1 induced HTN during pregnancy reduces placental mt function. Importantly, PIBF improved placental mt function and HTN, indicating the efficacy of improved progesterone signaling as potential therapeutics for PE.

Adoptive transfer of placental ischemia-stimulated natural killer cells causes a preeclampsia-like phenotype in pregnant rats.

PROBLEM: The Reduced Uterine Perfusion Pressure (RUPP) rat model of placental ischemia recapitulates many characteristics of preeclampsia including maternal hypertension, intrauterine growth restriction (IUGR), and increased cytolytic natural killer cells (cNKs). While we have previously shown a 5-fold higher cytotoxicity of RUPP NKs versus normal pregnant NKs, their role in RUPP pathophysiology remains unclear. In this study, we tested the hypotheses that (1) adoptive transfer of RUPP-stimulated NKs will induce maternal hypertension and IUGR in normal pregnant control (Sham) rats and (2) adoptive transfer of Sham NKs will attenuate maternal hypertension and IUGR in RUPP rats. METHOD OF STUDY: On gestation day (GD)14, vehicle or 5 × 106 RUPP NKs were infused i.v. into a subset of Sham rats (Sham+RUPP NK), and vehicle or 5 × 106 Sham NKs were infused i.v. into a subset of RUPP rats (RUPP+Sham NK; n = 12/group). On GD18, Uterine Artery Resistance Index (UARI) was measured. On GD19, mean arterial pressure (MAP) was measured, animals were sacrificed, and blood and tissues were collected for analysis. RESULTS: Adoptive transfer of RUPP NKs into Sham rats resulted in elevated NK activation, UARI, placental oxidative stress, and preproendothelin expression as well as reduced circulating nitrate/nitrite. This led to maternal hypertension and IUGR. RUPP recipients of Sham NKs demonstrated normalized NK activation, sFlt-1, circulating and placental VEGF, and UARI, which led to improved maternal blood pressure and normal fetal growth. CONCLUSION: These data suggest a direct role for cNKs in causing preeclampsia pathophysiology and a role for normal NKs to improve maternal outcomes and IUGR during late gestation.