Receptor Agonistic Autoantibodies Research Articles

The role of T cell stimulated agonistic autoantibodies to the angiotensin II type I receptor (AT1-AA) in mediating multiorgan dysfunction in IL-17 induced hypertension during pregnancy.

Preeclampsia (PE), new-onset hypertension during pregnancy accompanied by organ dysfunction, is associated with chronic inflammation including elevated IL-17, CD4+ T cells, B cells and natural killer (NK) cells. IL-17 can serve as a signal for either the adaptive or innate immune activation. We have previously shown that IL-17 contributes to increased blood pressure in association with elevated TH17 cells, NK cells and B cells secreting angiotensin II type 1 receptor agonistic autoantibodies (AT1-AA) during pregnancy. Moreover, we have shown an important role for CD4+T cells and AT1-AA in multiorgan dysfunction as measured by mitochondrial oxidative stress (mt ROS). However, we do not know the role of adaptive immune cells such as T cells or B cells secreting AT1-AA in mediating the PE phenotype in response to elevated IL-17. In order to answer this question, we infused IL-17 (150 pg/day i.p.) into either Sprague Dawley (SD) or athymic nude rats via mini-osmotic pump from gestational day (GD) 14-19 of pregnancy. On GD 19, blood pressure was determined and NK cells, mtROS and respiration and AT1-AA production from B cells were measured. Infusion of IL-17 increased blood pressure in the presence or absence of T cells. Mean arterial pressure (MAP) increased with IL-17 from 98±2mm Hg (n=12) to 114±2 (n=12) in SD rats and from 99±4mm Hg (n=7) versus 115±2mm Hg (n=7) in athymic nude rats. Similar trends were seen in NK cells and placental mt ROS. Knowing that IL-17 stimulates AT1-AA in SD pregnant rats, we included a group of SD and athymic nude pregnant rats infused with IL-17 and the AT1-AA inhibitor peptide ('n7AAc'). The inhibitor attenuated blood pressure (104.9±3.2, p=.0001) and normalized NK cells and mt function in SD pregnant rats. Importantly, the AT1-AA was not produced in pregnant nude IL-17 treated rats, nor did 'n7AAc' effect MAP, in nude athymic rats. These findings suggest two conclusions; one is that IL-17 causes hypertension and multiorgan dysfunction in the absence of T cells and AT1-AA, possibly through its activation of innate cells and secondly, in the presence of T cells, blockade of the AT1-AA attenuates the effect of IL-17. This study indicates the critical effects of elevated IL-17 during pregnancy and suggest treatment modalities to consider for PE women.

17-Hydroxyprogesterone caproate lowers angiotensin II type 1 receptor agonistic autoantibody and improves hypertension in early-onset preeclampsia

Preeclampsia (PE), new onset hypertension and significant end-organ dysfunction with or without proteinuria after 20 weeks of gestation, affects 8% of all pregnancies in the U.S. and it is associated with progesterone deficiency, chronic inflammation, elevated angiotensin II type 1 receptor agonistic autoantibody (AT1-AA) and endothelial dysfunction. Currently, the early delivery of the feto-placental remains the best treatment for PE. Elevations in progesterone and T helper 2 cytokines favor the immunotolerance of the fetus during healthy pregnancy. Progesterone, through its receptors, stimulates anti-inflammatory and vasodilatory pathways. Therefore, this study was designed to test the hypothesis that progesterone, in the form of 17-hydroxyprogesterone caproate (17-OHPC), lowers AT1-AA and inflammation while reducing maternal blood pressure in women with early-onset preeclampsia (EO-PE). PE women received 17-OHPC (250 mg, I.M.) and blood draws were collected before and after 17-OHPC treatment. Placentas were collected at the delivery. Progesterone and PIBF levels were 15.4 +/- 45.6 pg/mL (n=12), 14.4 +/- 1.0 ng/mL in PE (n=10), which significantly increased to 155+/-57.0 pg/mL, 16.39 +/-0.74 ng/mL (p< 0.05 vs. PE) in PE+17-OHPC (n=6). TNF-alpha and IL-6 were 41.3 +/- 3.9 pg/mL (n=8), 20.1 +/-7.9 (n=11) in PE, which decreased to 21.1+/-5.5 (n=6, p< 0.05 vs. PE), 5.2+/-2.1 in PE+17-OHPC (n=5). AT1-AA levels were 23+/-5.2 ΔBPM in PE (n=5), which significantly reduced to 2.1 ΔBPM in PE+17-OHPC (n=8, p< 0.05). 17-OHPC prolonged time of delivery beyond 72h on average and maternal blood pressure was 148 +/- 3.7 mmHg in PE (n=19), which significantly decreased to 136+/-4 in PE+17-OHPC (n=14, p< 0.05). In conclusion, 17-OHPC reduces AT1-AA and inflammation while improved blood pressure and maternal outcomes in response to early-onset preeclampsia. Supported by NIH grants RO1HD067541, 1U54GM115428, P20GM121334 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

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

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. 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. 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. 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. 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.

Empagliflozin Ameliorates Preeclampsia and Reduces Postpartum Susceptibility to Adriamycin in a Mouse Model Induced by Angiotensin Receptor Agonistic Autoantibodies.

Preeclampsia (PE) is the leading cause of maternal and perinatal morbidity and mortality and also is a risk factor for cardiovascular and kidney disease later in life. PE is associated with oversecretion of autoantibodies against angiotensin II type 1 receptor (AT1-AA) by the placenta into the maternal circulation. Here, we sought to determine the therapeutic value of the sodium-glucose co-transporter 2 (SGLT2) inhibitor empagliflozin (EMPA) in mice with AT1-AA-induced preeclampsia. Pregnant mice were injected with AT1-AA at gestation day (GD) 13 and treated daily with EMPA until GD 19, at which point some of the maternal mice were sacrificed and assessed. The other maternal mice were labored on time and challenged with adriamycin (ADR) at 12 weeks postpartum; their offspring were assessed for fetal outcomes. We showed that EMPA treatment significantly relieved high systolic blood pressure and proteinuria and ameliorated kidney injury in PE mice without affecting fetal outcomes. EMPA also ameliorated podocyte injury and oxidative stress, reduced the expression of SGLT2 and activated the AMPK/SIRT1 signaling pathway in vivo and in vitro. Remarkably, EMPA treatment during pregnancy reduced ADR-induced kidney and podocyte injury postpartum. These findings suggest that EMPA could be a potential pharmacological agent for PE.

Angiotensin II type 1 receptor agonistic autoantibody blockade improves postpartum hypertension and cardiac mitochondrial function in rat model of preeclampsia

Women with preeclampsia (PE) have a greater risk of developing hypertension, cardiovascular disease (CVD), and renal disease later in life. Angiotensin II type I receptor agonistic autoantibodies (AT1-AAs) are elevated in women with PE during pregnancy and up to 2-year postpartum (PP), and in the reduced uterine perfusion pressure (RUPP) rat model of PE. Blockade of AT1-AA with a specific 7 amino acid peptide binding sequence (‘n7AAc’) improves pathophysiology observed in RUPP rats; however, the long-term effects of AT1-AA inhibition in PP is unknown. Pregnant Sprague Dawley rats were divided into three groups: normal pregnant (NP) (n = 16), RUPP (n = 15), and RUPP + ‘n7AAc’ (n = 16). Gestational day 14, RUPP surgery was performed and ‘n7AAc’ (144 μg/day) administered via osmotic minipump. At 10-week PP, mean arterial pressure (MAP), renal glomerular filtration rate (GFR) and cardiac functions, and cardiac mitochondria function were assessed. MAP was elevated PP in RUPP vs. NP (126 ± 4 vs. 116 ± 3 mmHg, p < 0.05), but was normalized in in RUPP + ‘n7AAc’ (109 ± 3 mmHg) vs. RUPP (p < 0.05). PP heart size was reduced by RUPP + ’n7AAc’ vs. RUPP rats (p < 0.05). Complex IV protein abundance and enzymatic activity, along with glutamate/malate-driven respiration (complexes I, III, and IV), were reduced in the heart of RUPP vs. NP rats which was prevented with ‘n7AAc’. AT1-AA inhibition during pregnancy not only improves blood pressure and pathophysiology of PE in rats during pregnancy, but also long-term changes in blood pressure, cardiac hypertrophy, and cardiac mitochondrial function PP.

Association of Angiotensin II Type 1 Receptor Agonistic Autoantibodies With Outcomes in Patients With Acute Aortic Dissection

Angiotensin II is significantly associated with the pathogenesis of acute aortic dissection. Angiotensin II type 1 receptor agonistic autoantibodies (AT1-AAs) can mimic the effect of angiotensin II. To investigate the association between AT1-AAs and all-cause and cause-specific mortality risk in patients with acute aortic dissection. A total of 662 patients with clinically suspected aortic dissection from 3 medical centers in Wuhan, China, were enrolled in this cohort study from August 1, 2014, to July 31, 2016. Of these, 315 patients were included in the 3-year follow-up study. Follow-up was mainly performed via telephone interviews and outpatient clinic visits. Data analysis was conducted from March 1 to May 31, 2020. The primary outcomes of interest were all-cause mortality, death due to aortic dissection, and late aortic-related adverse events. The full study cohort included 315 patients with AAD (mean [SD] age, 56.2 [12.7] years; 230 men [73.0%]). Ninety-two patients (29.2%) were positive for AT1-AAs. The mortality of AT1-AA-positive patients was significantly higher than that of AT1-AA-negative patients (40 [43.5%] vs 37 [16.6%]; P < .001). The mortality risk in AT1-AA-positive patients was always significantly higher than that in AT1-AA-negative patients in patients with both type A and type B dissection. Multivariable analysis showed that the risk of AT1-AA-positive patients for type A dissection was significantly higher than that of AT1-AA-negative patients (odds ratio [OR], 1.88; 95% CI, 1.12-3.13; P = .02). The Cox proportional hazards regression model showed a significant increase of all-cause mortality risk (OR, 2.27; 95% CI, 1.44-3.57; P < .001) and late aortic-related adverse events (OR, 1.58; 95% CI, 1.06-2.36; P = .03) among AT1-AA-positive patients during the follow-up period compared with AT1-AA-negative patients. This cohort study first detected AT1-AAs in patients with acute aortic dissection. The presence of AT1-AAs was associated with significantly higher all-cause and cause-specific mortality during a follow-up period of 3 years. The antibodies may be a risk factor for aortic dissection.

Autoantibodies to LG3 are associated with poor long‐term survival after liver retransplantation

Autoantibodies are detrimental to the survival of organ transplantation. We demonstrated that Angiotensin II Type I Receptor agonistic autoantibodies (AT1R-AA) were associated with poor outcomes after liver retransplantation. To examine the effect of other autoantibodies, we studied a retrospective cohort of 93 patients who received a second liver transplant. Pre-retransplant sera were tested with Luminex-based solid-phase assays. Among 33 tested autoantibodies, 15 were significantly higher in 48 patients who lost their regrafts than 45 patients whose regrafts were still functioning. Specifically, patients with autoantibodies to the C-terminal laminin-like globular domain of Perlecan (LG3) experienced significantly worse regraft survival (p=.002) than those with negative LG3 autoantibodies (LG3-A). In multivariate analysis, LG3-A (HR=2.35 [1.11-4.98], p=.027) and AT1R-AA (HR=2.09 [1.07-4.10], p=.032) remained significant predictors of regraft loss after adjusting for recipient age and sex. There were synergistic deleterious effects on regraft survival in patients who were double-positive for LG3-A and donor-specific antibody (DSA) (HR=5.26 [2.15-12.88], p=.001), or LG3-A and AT1R-AA (HR=3.23 [1.37-7.66], p=.008). All six double-positive patients lost their liver regrafts. In conclusion, LG3-A is associated with inferior long-term outcomes of a second liver transplant. Screening anti-HLA antibodies and autoantibodies such as LG3-A/AT1R-AA identifies patients with a higher risk for liver transplantation.

The Role of Mitochondrial Dysfunction in Preeclampsia: Causative Factor or Collateral Damage?

Preeclampsia, new onset hypertension in pregnancy, affects ~5%-10% of the world's population. Preeclampsia is the leading cause of morbidity and mortality for both the mother and fetus. As of today, there is no cure for this disease except for delivery of the fetal-placental unit. The exact causation and onset of the disease are unknown. However, recent studies have shown a strong correlation between mitochondrial dysfunction and preeclampsia. Circulating mitochondrial DNA, elevated reactive oxygen species, angiotensin II type 1 receptor agonistic autoantibodies (AT1-AA), activated natural killer cells, and upregulated inflammatory responses all contribute to mitochondrial dysfunction and the pathophysiology of preeclampsia. This review summarizes the current literature of both experimental and clinical observations that support the hypothesis that mitochondrial dysfunction contributes to the pathophysiology of preeclampsia and may be a precursor to the disease onset. This review will also address the use of therapies to improve mitochondrial dysfunction in preeclampsia.

Angiotensin II type 1 receptor autoantibody blockade improves cerebral blood flow autoregulation and hypertension in a preclinical model of preeclampsia

ABSTRACT Introduction:Women with preeclampsia (PE) and reduced uterine perfusion pressure (RUPP) pre-clinical rat model of PE have elevated angiotensin II type 1 receptor agonistic autoantibodies (AT1-AA) and cerebrovascular dysfunction. Methods:Sprague Dawley rats had RUPP surgery with/without AT1-AA inhibitor (‘n7AAc’144 μg/day) osmotic minipumps. Mean arterial pressure (MAP), CBF autoregulation, blood brain barrier (BBB) permeability, cerebral edema, oxidative stress, and eNOS were assessed. Results:‘n7AAc’ improved MAP, restored CBF autoregulation, prevented cerebral edema, elevated oxidative stress, and increased phosphorylated eNOS protein in RUPP rats. Conclusion:Inhibiting the AT1-AA in placental ischemic rats prevents hypertension, cerebrovascular dysfunction, and improves cerebral metabolic function.

Vascular mechanisms and molecular targets in hypertensive pregnancy and preeclampsia.

Preeclampsia is a major complication of pregnancy manifested as hypertension and often intrauterine growth restriction, but the underlying pathophysiological mechanisms are unclear. Predisposing genetic and environmental factors cause placental maladaptations leading to defective placentation, apoptosis of invasive cytotrophoblasts, inadequate expansive remodeling of the spiral arteries, reduced uteroplacental perfusion pressure, and placental ischemia. Placental ischemia promotes the release of bioactive factors into the maternal circulation, causing an imbalance between antiangiogenic soluble fms-like tyrosine kinase-1 and soluble endoglin and proangiogenic vascular endothelial growth factor, placental growth factor, and transforming growth factor-β. Placental ischemia also stimulates the release of proinflammatory cytokines, hypoxia-inducible factor, reactive oxygen species, and angiotensin type 1 receptor agonistic autoantibodies. These circulating factors target the vascular endothelium, causing generalized endotheliosis in systemic, renal, cerebral, and hepatic vessels, leading to decreases in endothelium-derived vasodilators such as nitric oxide, prostacyclin, and hyperpolarization factor and increases in vasoconstrictors such as endothelin-1 and thromboxane A2. The bioactive factors also target vascular smooth muscle and enhance the mechanisms of vascular contraction, including cytosolic Ca2+, protein kinase C, and Rho-kinase. The bioactive factors could also target matrix metalloproteinases and the extracellular matrix, causing inadequate vascular remodeling, increased arterial stiffening, and further increases in vascular resistance and hypertension. As therapeutic options are limited, understanding the underlying vascular mechanisms and molecular targets should help design new tools for the detection and management of hypertension in pregnancy and preeclampsia.

Angiotensin II Type I Receptor Agonistic Autoantibody Blockade Improves Cerebral Blood Flow Autoregulation, Blood Brain Barrier Permeability, and Hypertension in the Pre‐Clinical Rat Model of Preeclampsia

BackgroundPreeclampsia (PE) is a pregnancy disorder that is characterized by an increase in blood pressure, angiotensin II type1 receptor agonistic autoantibodies (AT1‐AA), and neurological complications. The pre‐clinical RUPP (reduced uterine perfusion pressure) rat model of PE displays many of the clinical pathologies associated with PE, such as increased blood pressure, AT1‐AAs, blood brain barrier (BBB) permeability, and impaired cerebral blood flow (CBF) autoregulation.HypothesisWe hypothesized that specific inhibition of AT1‐AA, using the epitope binding 7 amino acid peptide sequence (7AA), will improve blood pressure, BBB integrity, and CBF autoregulation in RUPP rats.MethodsSprague Dawley rats, were divided into 3 groups: normal pregnant (NP) (n=19), RUPP (n=19), and RUPP+AT1‐AA inhibition (7AA) (n=21). RUPP surgery was performed on gestational day (GD) 14 and 7AA (2μg/μl) was administered via osmotic minipumps. GD 19, mean arterial pressure (MAP) was determined and BBB permeability was assessed using the in‐vivo imaging system (IVIS). CBF was measured by laser Doppler flowmetry through a 4 mm x 4 mm cranial window under anesthesia. MAP was elevated step‐wise from 100–190 mmHg by infusion of phenylephrine to determine changes in CBF.ResultsMAP was increased in RUPP vs NP (124±3 vs 100±1 mmHg, p&lt;0.05) and decreased in RUPP+7AA vs RUPP (105±2 vs 124±3 mmHg, p&lt;0.05) rats. Using IVIS, Texas Red/FITC green fluorescent imaging was decreased in RUPP+7AA vs RUPP (0.2±0.001 vs 0.6±0.001, p&lt;0.05), indicating improvement in BBB permeability with AT1‐AA inhibition. CBF autoregulation was impaired in RUPP vs NP rats at 140 mmHg (142±7 vs 119±4%, p&lt;0.05) and 160 mmHg (157±10 vs 129±6%, p&lt;0.05) (both pressures are within the normal CBF autoregulatory range). AT1‐AA inhibition prevented impaired CBF at 140mmHg (125±5 RUPP+7AA vs 142±7% RUPP, p&lt;0.05) and 160 mmHg (125±9 RUPP+7AA vs 157±10% RUPP, p&lt;0.05). Furthermore, the increases in CBF at pressures above the autoregulatory range, 180 mmHg (122±10 vs 198±17%, p&lt;0.05) and 190 mmHg (123±11 vs 208±19%, p&lt;0.05), was prevented in RUPP+7AA vs RUPP, respectively.ConclusionAT1‐AA inhibition improved blood pressure, BBB permeability, and CBF autoregulation in the pre‐clinical RUPP rat model of PE, indicating that AT1‐AA inhibition may be a potential therapy used to improve neurological complications during PE.Support or Funding InformationSupported: AHA18CDA34110264

Reciprocal upregulation of hypoxia-inducible factor-1α and persistently enhanced placental adenosine signaling contribute to the pathogenesis of preeclampsia.

Recent evidence indicates that elevated placental adenosine signaling contributes to preeclampsia (PE). However, the molecular basis for the chronically enhanced placental adenosine signaling in PE remains unclear. Here, we report that hypoxia-inducible factor-1α (HIF-1α) is crucial for the enhancement of placental adenosine signaling. Utilizing a pharmacologic approach to reduce placental adenosine levels, we found that enhanced adenosine underlies increased placental HIF-1α in an angiotensin receptor type 1 receptor agonistic autoantibody (AT1 -AA)-induced mouse model of PE. Knockdown of placental HIF-1α in vivo suppressed the accumulation of adenosine and increased ecto-5'-nucleotidase (CD73) and adenosine A2B receptor (ADORA2B) in the placentas of PE mouse models induced by AT1 -AA or LIGHT, a TNF superfamily cytokine (TNFSF14). Human in vitro studies using placental villous explants demonstrated that increased HIF-1α resulting from ADORA2B activation facilitates the induction of CD73, ADORA2B, and FLT-1 expression. Overall, we demonstrated that (a) elevated placental HIF-1α by AT1 -AA or LIGHT upregulates CD73 and ADORA2B expression and (b) enhanced adenosine signaling through upregulated ADORA2B induces placental HIF-1α expression, which creates a positive feedback loop that promotes FLT-1 expression leading to disease development. Our results suggest that adenosine-based therapy targeting the malicious cycle of placental adenosine signaling may elicit therapeutic effects on PE.

Blockade of endogenous angiotensin II type I receptor agonistic autoantibody activity improves mitochondrial reactive oxygen species and hypertension in a rat model of preeclampsia

Preeclampsia (PE) is characterized by new-onset hypertension that usually occurs in the third trimester of pregnancy and is associated with oxidative stress and angiotensin II type 1 receptor agonistic autoantibodies (AT1-AAs). Inhibition of the AT1-AAs in the reduced uterine perfusion pressure (RUPP) rat, a model of PE, attenuates hypertension and many other characteristics of PE. We have previously shown that mitochondrial oxidative stress (mtROS) is a newly described PE characteristic exhibited by the RUPP rat that contributes to hypertension. However, the factors that cause mtROS in PE or RUPP are unknown. Thus, the objective of the current study is to use pharmacologic inhibition of AT1-AAs to examine their role in mtROS in the RUPP rat model of PE. AT1-AA inhibition in RUPP rats was achieved by administration of an epitope-binding peptide ('n7AAc'). Female Sprague-Dawley rats were divided into the following two groups: RUPP and RUPP + AT1-AA inhibition (RUPP + 'n7AAc'). On day 14 of gestation (GD), RUPP surgery was performed; 'n7AAc' peptide (2 µg/μL) was administered by miniosmotic pumps in a subset of RUPP rats; and on GD19, sera, placentas, and kidneys were collected. mitochondrial respiration and mtROS were measured in isolated mitochondria using the Oxygraph 2K and fluorescent microplate reader, respectively. Placental and renal mitochondrial respiration and mtROS were improved in RUPP + 'n7AAc' rats compared with RUPP controls. Moreover, endothelial cells (human umbilical vein endothelial cells) treated with RUPP + 'n7AAc' sera exhibited less mtROS compared with those treated with RUPP sera. Overall, our findings suggest that AT1-AA signaling is one stimulus of mtROS during PE.

Angiotensin II type I receptor agonistic autoantibodies are associated with poor allograft survival in liver retransplantation.

Angiotensin II type I receptor (AT1R) agonistic autoantibodies (AT1R-AA) are detrimental to kidney transplantation. Early studies suggested a similar negative effect in primary liver transplantation. Here, we studied AT1R-AA in a retrospective cohort of 94 patients who received a second liver transplant to determine their prevalence and effects. The concentrations of preformed AT1R-AA before transplantation were higher (P=.019) in the 48 patients who lost their liver grafts than in the 46 patients whose grafts survived. About half (48/94, 51.1%) of the patients were positive for AT1R-AA >17U/mL before the second liver transplantation. In 22 (23.4%) patients, strong positive AT1R-AA (defined as >40U/mL) were detected, of whom 16 (72.7%) patients lost their grafts. Based on Kaplan-Meier analysis, patients with strong positive AT1R-AA had significantly worse graft survival than those with AT1R-AA <40U/mL (P=.035). In multivariate Cox models that included confounders such as sex and age, either AT1R-AA >40U/mL (HR=1.999 [1.085-3.682], P=.026) or increased concentrations of AT1R-AA (HR=1.003 [1.001-1.006] per incremental U/mL, P=.019) were significantly associated with elevated risk for graft loss. In conclusion, our data indicate that there is a high prevalence of AT1R-AA in candidates for second liver transplantation and that their presence is associated with inferior long-term outcomes of the second graft.

Abstract P1103: Angiotensin II Type I Receptor Agonistic Autoantibody Blockade Improves Hypertension and Immune Activation in Postpartum Preeclamptic Rats

Women with preeclampsia (PE) have a risk of developing cardiovascular diseases (CVD) later in life. The angiotensin II type I receptor agonistic autoantibodies (AT1-AAs) are elevated in women with PE, PE women 2 years post-partum (PP), and the reduced uterine perfusion pressure (RUPP) rat model of PE. Blockade of the AT1-AA by using a specific binding seven amino acid peptide sequence (7AA) improves the pathology of PE in RUPP rats. The long-term effects of AT1-AA inhibition on blood pressure, NK cell activation, heart mitochondria (mt) proteins, and CVD in the RUPP model PP is unknown. Therefore, we hypothesized that PP RUPP rats have elevated blood pressure, NK cell activation, and changes in heart mt proteins, which will be prevented in RUPP rats administered the 7AA during pregnancy. Methods: Pregnant Sprague Dawley rats were divided into groups; normal pregnant (NP) (n=7), RUPP (n=10), and RUPP+7AA (n=9). Gestational day 14, RUPP surgery was performed and 7AA (2 μg/ml) administered via minipump. Results: At 8 and 10 weeks (wks) PP, blood pressure (MAP), blood, and hearts were collected. NK cells were quantified by flow cytometry. At 8 wks PP, MAP was elevated in RUPP vs. NP (130±2 vs. 123±4 mmHg, ns), and RUPP+7AA (124±4 mmHg) treatment prevented this increase. At 10 wks, MAP was elevated in RUPP vs NP (133±5 vs. 120±5 mmHg, p=0.08), with a significant decrease in MAP in RUPP+7AA (107±6 mmHg) vs. RUPP (p&lt;0.05). Total circulating NK cells were increased in RUPP vs NP (45±9. vs. 29± 8% gated cells, ns), which was prevented in RUPP+7AA (19±16 % gated cells) at 8 wks PP. Hearts were enlarged with RUPP vs NP (0.41±0.04 vs. 0.36±0.02g/100gBW, ns), which was normalized in RUPP+7AA (0.34±0.02g/100gBW). Previous studies show that during pregnancy complex IV is significantly lower along with a decrease mt function in RUPP vs NP. Complex IV mt proteins in the heart were elevated in RUPP+7AA vs. RUPP (5.5±1.7 vs. 3.0±0.2 AU, ns). Conclusion: In summary, PP PE rats have an increase in MAP, NK cells, and larger hearts. AT1-AA inhibition restores complex IV mt levels and improves HTN, immune activation, and cardiac hypertrophy PP. This study highlights the importance of AT1-AA inhibition during PE to prevent CVD later in life. Supported: AHA18CDA34110264

Angiotensin receptor autoantibodies as exposures that modify disease progression: Cross sectional, longitudinal and in vitro studies of prostate cancer

Circulating angiotensin type I receptor (AT1R) agonistic autoantibodies (AT1RaAbs) that bind and chronically activate the receptor have been associated with a number of diseases suggesting that while the autoantibodies are not necessarily causative they may promote disease progression. The prostate has a local renin angiotensin system. The current study examines associations between AT1RaAbs and prostate cancer (PCA), disease-free survival (DFS), overall survival (OS) and AT1RaAb effects on PCA cell phenotype.In a cross-sectional set of serum obtained from 151 men diagnosed with PCA, nonmalignant prostate disease or no disease, higher serum AT1RaAb levels were associated with PCA and non-organ confined PCA. The odds ratio for PCA was 6.3 (95% confidence interval 2.2 to 18) for a positive 1:1600 titer and 18 (95% confidence interval 6.9 to 45) at AT1RaAb levels > 1.04 μg/ml, (p < 0.0001). In a longitudinal set of pre-diagnosis samples from 109 men, DFS hazard ratios of 2.2 (95% confidence interval 1.4 to 3.5) and 1.6 (95% confidence interval 1.0 to 2.5) for most proximal to diagnosis and most distal to diagnosis samples, respectively, were found for high versus low AT1RaAb groups. Hazard ratios for OS in most proximal and distal samples were 2.4 (95% confidence interval 1.6 to 3.6) and 1.8 (95% confidence interval 1.1 to 2.8), respectively. Accelerated failure modeling of survival indicated that a 1 μg/ml increase in AT1RaAb levels was associated with a reduction of DFS and OS by 20% at the most proximal time point and by 15% at the most distal time points. Adjusting for age, did not affect the association with DFS in proximal samples but changed distal time point DFS and OS to a 10% decrease for every 1 μg/ml increase in AT1RaAb. Additional adjustments for body mass index, systolic blood pressure and prostate-specific antigen did not appreciably alter these associations. AT1RaAb treatment of PC3, DU145, and LNCaP cells significantly increased the maximal growth rate approximately 2-fold and invasiveness approximately 3-fold. ConclusionsThese observations provide evidence supporting AT1RaAbs as exposures that may modify prostate cancer progression and indicate they may be predictive markers for risk stratification.

Molecular determinants of microvascular dysfunction in hypertensive pregnancy and preeclampsia.

Preeclampsia is a pregnancy-related disorder characterized by hypertension and often fetal intrauterine growth restriction, but the underlying mechanisms are unclear. Defective placentation and apoptosis of invasive cytotrophoblasts cause inadequate remodeling of spiral arteries, placental ischemia, and reduced uterine perfusion pressure (RUPP). RUPP causes imbalance between the anti-angiogenic factors soluble fms-like tyrosine kinase-1 and soluble endoglin and the pro-angiogenic vascular endothelial growth factor and placental growth factor, and stimulates the release of proinflammatory cytokines, hypoxia-inducible factor, reactive oxygen species, and angiotensin AT1 receptor agonistic autoantibodies. These circulating factors target the vascular endothelium, smooth muscle and various components of the extracellular matrix. Generalized endotheliosis in systemic, renal, cerebral, and hepatic vessels causes decreases in endothelium-derived vasodilators such as nitric oxide, prostacyclin and hyperpolarization factor, and increases in vasoconstrictors such as endothelin-1 and thromboxane A2. Enhanced mechanisms of vascular smooth muscle contraction, such as intracellular Ca2+ , protein kinase C, and Rho-kinase cause further increases in vasoconstriction. Changes in matrix metalloproteinases and extracellular matrix cause inadequate vascular remodeling and increased arterial stiffening, leading to further increases in vascular resistance and hypertension. Therapeutic options are currently limited, but understanding the molecular determinants of microvascular dysfunction could help in the design of new approaches for the prediction and management of preeclampsia.

Angiotensin II Type I Receptor Agonistic Autoantibody Induces Podocyte Injury via Activation of the TRPC6- Calcium/Calcineurin Pathway in Pre-Eclampsia

Background/Aims: Angiotensin II type I receptor agonistic autoantibody (AT1-AA) is closely related to pre-eclampsia, which is characterized by proteinuria and hypertension. AT1-AA has been shown to enhance the effect of AngII in pre-eclampsia, such as production of endothelin-1, activation of ROS, and vasoconstriction, which are considered to be associated with hypertension; however, whether or not AT1-AA participates in podocyte damage leading to the generation of proteinuria has not been reported. In this study we investigated the role of pre-eclamptic serum AT1-AA on podocytes and the mechanism underlying the generation of proteinuria. Methods: The levels of AT1-AA isolated from pre-eclamptic sera were determined by an enzyme-linked immunosorbent assay. Human podocytes were cultured in vitro and treated with various concentrations of AT1-AA. Whether or not an ERK1/2 inhibitor and TRPC6 siRNA inhibit the effect of AT1-AA on podocytes was determined. Western blot was used to detect the expression of podocyte-specific proteins (nephrin, synaptopodin, and podocin) and the phosphorylation of ERK1/2 and TRPC6. The arrangement of F-actin was observed by immunofluorescence. A Calcineurin Cellular Activity Assay Kit was used to detect calcineurin activity. Changes in the intracellular Ca²⁺ concentration was determined by confocal laser. Results: AT1-AA induced a decrease in podocyte-specific protein expression and calcineurin activity and increased expression of p-ERK1/2 and TRPC6 protein and the intracellular Ca²⁺ concentration. Immunofluorescence revealed rearrangement of F-actin. PD98059, an inhibitor of ERK1/2, and TRPC6 siRNA attenuated the decreased expression of podocyte-specific proteins and decreased intracellular Ca²⁺ concentration. The expression of TRPC6 was reduced following the addition of ERK1/2 inhibitor. Conclusion: AT1-AA induced podocyte damage in a dose-dependent manner. The underlying mechanism might involve activation of the TRPC6 –calcium/calcineurin pathway. This study provides new details regarding podocyte injury and the mechanism underlying the generation of proteinuria in pre-eclampsia.

Progesterone attenuates hypertension and autoantibody levels to the angiotensin II type 1 receptor in response to elevated cadmium during pregnancy

IntroductionPreeclampsia is associated with the presence of pathogenic angiotensin-receptor-activating autoantibodies. Cadmium is an increasingly prevalent environmental pollutant that can mimic oestrogens, which may enhance immunoglobulin production. Progesterone exerts opposite effects to oestrogen. MethodsWe measured the levels of cadmium and progesterone in preeclamptic patients and controls. Pregnant rats exposed to cadmium (0.125 mg/kg body weight) from gestational day 9–12 were treated with/without progesterone (3 mg/kg) beginning from gestational day 9 to delivery. We analysed the main features of preeclampsia and circulating level of the angiotensin II type 1 receptor agonistic autoantibody. We also measured the expression of activation-induced cytosine deaminase in B cells. ResultsThere were higher cadmium levels and lower progesterone levels in the blood of preeclamptic women than in the blood of those with a healthy pregnancy. Based on this finding, a rat model of preeclampsia was established by intraperitoneally administrating low-dose cadmium on gestational days 9–12. Rats were then treated with/without progesterone. Key features of preeclampsia, including hypertension, proteinuria and placental abnormalities, appeared in pregnant rats after cadmium injection and improved after treatment with progesterone. Cadmium increased immunoglobulin production, mainly angiotensin II type 1-receptor-agonistic autoantibodies, by increasing the expression of activation-induced cytosine deaminase in B cells; progesterone exerted an opposite effect. ConclusionCadmium induced immune abnormalities that may be a key pathogenic contributor to preeclampsia. Progesterone supplementation to correct hormonal imbalance may be a viable strategy for preeclampsia management.

Abstract 142: Angiotensin II Type 1 Receptor Autoantibody Inhibition Improves Blood Pressure and Markers of Neurological Damage and Oxidative Stress in Brains of Placental Ischemic Rats During Pregnancy

Preeclampsia (PE), hypertension in response to placental ischemia, is associated with angiotensin II type 1 receptor agonistic autoantibodies (AT1-AA), oxidative stress, and neurological complications, such as headaches, blurred vision, and seizures which could lead to stroke and death. We hypothesize that AT1AAs play a role in the cerebral pathology of PE. The objective of this study was to determine if administration of a specific peptide sequence to inhibit the AT1-AA from binding to the AT1 receptor, will improve blood pressure (MAP) and cerebral oxidative stress in the reduced uterine perfusion pressure (RUPP) rat model of PE. Pregnant Sprague Dawley rats were divided into 2 groups: RUPP (n=5) and RUPP+AT1-AA inhibitory peptide (7AA) (n=3). RUPP surgery was performed on gestational day (GD) 14 and the 7AA was administered (2ug/μl saline) via mini-osmotic pumps. On GD 19, MAP was determined and brains collected. Western blots were stained for Glial Fibrillary Acidic Protein (GFAP), endothelial NO synthase (eNOS), phosphorylated eNOS and NADPH oxidase activity was determined using chemilumenescence. MAP was decreased in RUPP+7AA vs. RUPP (95±2 vs. 130±6 mmHg). Brain/body weight ratio, which is indicative of edema, was reduced in RUPP+7AA (5.8±0.25 vs. 6.5±0.25 grams) vs. RUPP. NADPH oxidase activity was lower in RUPP+7AA (33275±3122 vs. 57408±10508 RLU/min/mg protein). Phosphorylated eNOS was 2 fold higher in the RUPP+7AA vs. RUPP (0.4±0.1 vs. 0.2±0.04 AU) and the phosphorylated eNOS/eNOS ratio was elevated (0.4±0.12 vs. 0.2±0.04 AU). GFAP a marker for activated astrocytes that increases during neurologic injury and serves as a compensatory mechanism for brain injury recovery was elevated in RUPP+7AA vs. RUPP (3.2±1.3 vs. 0.5±0.2 AU). Administration of AT1-AA inhibitory peptide to RUPP rats decreased blood pressure and improved markers of NO bioavailability, injury (GFAP), and cerebral swelling. In conclusion, our preliminary data suggests that AT1-AA inhibition could be a potential therapy to improve peripheral and neurological complications during PE. Research Supported by T32HL105324 (Cunningham), RO1HD067541-06 (LaMarca), DK-104184 (Roman), 050049 (Fan), P20-GM-104357 (cores B and C-Roman; Pilot-Fan) and AHA 16GRNT31200036 (Fan).