The renin-angiotensin system (RAS) participates in preeclampsia; however, the relative contributions from the circulating RAS and the tissue-based, uteroplacental RAS are unknown. We hypothesized that the tissue-based uteroplacental RAS is dysregulated in preeclampsia. We performed microarray and gene expression studies and confirmed the findings on the protein level by immunohistochemistry in ureteroplacental units from 10 preeclamptic women and 10 women with uneventful pregnancies. All of the women were delivered by cesarean section. We also analyzed plasma renin activity and circulating agonistic angiotensin II type 1 (AT ₁ ) receptor autoantibodies. In preeclampsia, we found that the angiotensin II AT ₁ receptor gene was 5-fold upregulated in decidua (maternal origin). We also found AT ₁ autoantibodies in preeclamptic women and in their offspring by neonatal cardiomyocyte bioassay compared with women with normal pregnancies and their infants (mother: 17.5±2.2 versus 0.05±0.4; fetus: 14.5±1.8 versus 0.5±0.5 Δbpm). Gene expressions for renin (35.0-fold), angiotensin-converting enzyme (2.9-fold), and angiotensinogen (8.9-fold) were higher in decidua than placenta (fetal origin) in both control and preeclamptic women, whereas the AT ₁ receptor was expressed 10-fold higher in placenta than in decidua in both groups. Our findings elucidate the ureteroplacental unit RAS in preeclamptic and normal pregnancies. We found that, in preeclampsia, the AT ₁ receptor expression is particularly high in decidua, combined with pregnancy-specific tissue RAS involving decidual angiotensin II production and AT ₁ autoantibodies. We also showed that AT ₁ autoantibodies cross the ureteroplacental barrier. These components could participate in the pathophysiology of preeclampsia.

Circulating factors, such as agonistic autoantibodies to the angiotensin II type 1 (AT1) receptor (AT1-AAs), and inflammatory cytokines, including tumor necrosis factor α (TNF-α), are suggested to be important links between placental ischemia and hypertension in preeclamptic women. The purpose of this study was to determine the role of placental ischemia and TNF-α in stimulating the AT1-AA and the importance of AT1 receptor activation in mediating hypertension during reductions in uterine perfusion pressure (RUPP) and chronic TNF-α excess in pregnant rats. Increased mean arterial pressure in RUPP pregnant rats (122±1 mm Hg RUPP versus 101±1 mm Hg normal pregnant [NP]; P <0.001) was associated with increased circulating TNF-α (RUPP 48±13 pg/mL versus N 8±1 pg/mL; P <0.05) and AT1-AA (RUPP 15.3±1.6 U versus NP 0.6±0.3 U; P <0.001). Moreover, TNF-α–induced hypertension (97±2 to 112±2 mm Hg; P <0.05) in pregnant rats was associated with AT1-AA production (TNF-α rats 9.2±2.3 U versus NP rats 1.0±0.8 U; P <0.05). To determine the importance of AT1 receptor activation in mediating hypertension in RUPP– and TNF-α–treated rats, we administered an AT1 receptor antagonist to RUPP–, TNF-α–treated, and NP rats. Blood pressure responses were attenuated in RUPP rats (Δ 32 mm Hg versus Δ 20 mm Hg, NP; P <0.001), as well as in TNF-α–treated rats (Δ 10 mm Hg versus Δ 5 mm Hg, NP; P <0.05). Collectively, these data indicate that placental ischemia and TNF-α are important stimuli of AT1-AA, and activation of the AT1 receptor appears to, in part, mediate hypertension produced by RUPP and TNF-α in pregnant rats.

Preeclampsia is a devastating pregnancy-associated disorder affecting 5% to 8% of pregnant women worldwide. It emerges as an autoimmune-driven disease, and, among others, the autoantibodies against angiotensin type 1 receptor II have been proposed to account for preeclampsia symptoms. Despite much attention focused on describing autoantibodies associated with preeclampsia, there is no clue concerning the cell population producing them. CD19 ⁺ CD5 ⁺ B-1a B cells constitute the main source of natural and polyreactive antibodies, which can be directed against own structures. Here, we aimed to identify the B-cell subpopulation responsible for autoantibody production during preeclampsia and to study their regulation, as well as their possible use as markers for the disease. The frequency of CD19 ⁺ CD5 ⁺ cells in peripheral blood of preeclamptic patients is dramatically increased compared with normal pregnant women as analyzed by flow cytometry. This seems to be driven by the high human chorionic gonadotropin levels present in the serum and placenta supernatant of preeclamptic patients versus normal pregnant women. Not only ≈95% of CD19 ⁺ CD5 ⁺ cells express the human chorionic gonadotropin receptor, but these cells also expand on human chorionic gonadotropin stimulation in a lymphocyte culture. Most importantly, isolated CD19 ⁺ CD5 ⁺ cells produce autoantibodies against angiotensin type 1 receptor II, and CD19 ⁺ CD5 ⁺ cells were further detected in the placenta of preeclamptic but not of normal pregnancies where barely B cells are present. Our results identify a B-cell population able to produce pregnancy-pathological autoantibodies as possible markers for preeclampsia, which opens vast diagnostic and therapeutic applications.

Activating angiotensin II type 1 autoantibodies (AT1-AAs) develop in women with preeclampsia and may contribute to the disorder. Insulin resistance and serum concentrations of the antiangiogenic soluble fms-like tyrosine kinase 1 (sFlt-1) are also increased in women with preeclampsia compared with normal pregnancy. sFlt-1 and insulin resistance decrease substantially after delivery; however, significant group differences persist postpartum. Women who have had preeclampsia are at increased cardiovascular risk later in life. We measured AT1-AAs in groups of women with previous preeclampsia (n=29) and previous normal pregnancies (n=35) 18±9 months after the first completed pregnancy. These women had had sFlt-1, insulin resistance homeostasis model assessment score, and related cardiovascular risk factors measured. Activating antibodies were detected by the chronotropic response of cultured neonatal rat cardiomyocytes coupled with receptor-specific antagonists (losartan and prazosin). AT1-AAs were detected in 17.2% of women with previous preeclampsia versus 2.9% of women with previous uncomplicated pregnancies ( P <0.05). In contrast, there was no difference in the prevalence of autoantibodies against the α1-adrenoceptor (10% of previous preeclamptic versus 14% of previous normal pregnant). Women with activating autoantibodies had significantly increased sFlt-1, reduced free vascular endothelial growth factor, and higher insulin resistance homeostasis model assessment values compared with autoantibody-negative women. These data suggest that, as with sFlt-1 and insulin resistance, the AT1-AA does not regress completely after delivery and, secondarily, that correlations exist among these variables. The impact of AT1-AA after preeclampsia, especially in the context of cardiovascular risk, remains to be determined.

Preeclampsia is associated with autoimmune cells T_H17, 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.

Pregnant women who subsequently develop preeclampsia are highly sensitive to infused angiotensin (Ang) II; the sensitivity persists postpartum. Activating autoantibodies against the Ang II type 1 (AT ₁ ) receptor are present in preeclampsia. In vitro and in vivo data suggest that they could be involved in the disease process. We generated and purified activating antibodies against the AT ₁ receptor (AT ₁ -AB) by immunizing rabbits against the AFHYESQ epitope of the second extracellular loop, which is the binding epitope of endogenous activating autoantibodies against AT ₁ from patients with preeclampsia. We then purified AT ₁ -AB using affinity chromatography with the AFHYESQ peptide. We were able to detect AT ₁ -AB both by ELISA and a functional bioassay. We then passively transferred AT ₁ -AB into pregnant rats, alone or combined with Ang II. AT ₁ -AB activated protein kinase C-α and extracellular-related kinase 1/2. Passive transfer of AT ₁ -AB alone or Ang II (435 ng/kg per minute) infused alone did not induce a preeclampsia-like syndrome in pregnant rats. However, the combination (AT ₁ -AB plus Ang II) induced hypertension, proteinuria, intrauterine growth retardation, and arteriolosclerosis in the uteroplacental unit. We next performed gene-array profiling of the uteroplacental unit and found that hypoxia-inducible factor 1α was upregulated by Ang II plus AT ₁ -AB, which we then confirmed by Western blotting in villous explants. Furthermore, endothelin 1 was upregulated in endothelial cells by Ang II plus AT ₁ -AB. We show that AT ₁ -AB induces Ang II sensitivity. Our mechanistic study supports the existence of an “autoimmune-activating receptor” that could contribute to Ang II sensitivity and possible to preeclampsia.