Gloria Valdés

Endothelial Dysfunction: A Link Among Preeclampsia, Recurrent Pregnancy Loss, and Future Cardiovascular Events?

We tested the hypothesis that endothelial dysfunction could cause placentation-related defects, persist after the complicated pregnancy, and probably cause cardiovascular disease later in life. Brachial arterial reactivity and factors related to endothelial dysfunction, such as circulating cholesterol, uric acid, nitrites, l-arginine, asymmetrical dimethylarginine, vascular endothelial growth factor, and soluble vascular endothelial growth factor receptor-1, in women with previous healthy pregnancies (n=22), patients with severe preeclampsia (n=25), or patients with recurrent pregnancy loss (n=29), at day 10 of the luteal phase of an ovulatory cycle an average of 11 to 27 months after pregnancy were evaluated. Both groups with placentation defects had a significant decrease in endothelium-dependent dilatation, a higher rate of endothelial dysfunction, lower serum nitrites, and higher cholesterol as compared with control subjects; subjects with previous preeclampsia additionally had higher normal blood pressures and a greater parental prevalence of cardiovascular disease. Patients with recurrent pregnancy loss also demonstrated a significantly lower endothelium-independent vasodilatation. A trend to an inverse correlation was found between serum cholesterol serum and endothelial-mediated vasodilatation in the whole study population. Uric acid, l-arginine, asymmetrical dimethylarginine, vascular endothelial growth factor, and soluble vascular endothelial growth factor receptor-1 were similar in all of the groups. We postulate that endothelial dysfunction may represent a link between preeclampsia and increased cardiovascular disease latter in life and propose that women with unexplained recurrent miscarriages are also at increased cardiovascular risk. The identification and correction of endothelial dysfunction detected during the reproductive stage on obstetric outcome and on cardiovascular diseases needs to be elucidated.

Bile acids increase response and expression of human myometrial oxytocin receptor.

OBJECTIVE We tested the hypothesis that during intrahepatic cholestasis of pregnancy bile acids activate the myometrial oxytocin receptor pathway. STUDY DESIGN Myometrial sensitivity to oxytocin and oxytocin-receptor messenger RNA and protein level was investigated. The ability of cholic acid to mediate such changes was evaluated. RESULTS Cholestasis patients required lesser oxytocin to elicit four uterine contractions in 10 minutes (1.3+/-0.6 vs 3.6+/-0.8 U, P<.05, n=7) and had lower in vitro ED(50) (1.6 x 10(-10) mol/L vs 1.0 x 10(-8) mol/L, P<.05, n=7) than controls. The 24-hour incubation of control myometrial strips (n=7) with cholic acid (20 micromol/L) increased oxytocin sensitivity. Incubation of cultured myometrial cells (n=5) with cholic acid increased oxytocin-receptor expression (messenger RNA and protein). CONCLUSION We demonstrate that during intrahepatic cholestasis of pregnancy, an activation of the oxytocin receptor pathway occurs. This event seems to be the result of a cholic acid-mediated increase in oxytocin-receptor expression.

The uterine placental bed Renin-Angiotensin system in normal and preeclamptic pregnancy.

Previously, we demonstrated activation of the renin-angiotensin system in the fetal placental chorionic villi, but it is unknown whether the immediately adjacent area of the maternal uterine placental bed is regulated similarly. This study measured angiotensin peptides, renin-angiotensin system component mRNAs, and receptor binding in the fundus from nonpregnant subjects (n = 19) and in the uterine placental bed from normal (n = 20) and preeclamptic (n = 14) subjects. In the uterine placental bed from normal pregnant women, angiotensin II peptide levels and angiotensinogen, angiotensin-converting enzyme, angiotensin receptor type 1 (AT(1)), AT(2), and Mas mRNA expression were lower as compared with the nonpregnant subjects. In preeclamptic uterine placental bed, angiotensin II peptide levels and renin and angiotensin-converting enzyme mRNA expression were significantly higher than normal pregnant subjects. The AT(2) receptor was the predominant receptor subtype in the nonpregnant fundus, whereas all angiotensin receptor binding was undetectable in normal and preeclamptic pregnant uterine placental bed compared with nonpregnant fundus. These findings suggest that the maternal uterine placental bed may play an endocrine role by producing angiotensin II, which acts in the adjacent placenta to vasoconstrict fetal chorionic villi vessels where we have shown previously that AT(1) receptors predominate. This would lead to decreased maternal-fetal oxygen exchange and fetal nutrition, a known characteristic of preeclampsia.

Enhanced expression of Ang-(1-7) during pregnancy

Pregnancy is a physiological condition characterized by a progressive increase of the different components of the renin-angiotensin system (RAS). The physiological consequences of the stimulated RAS in normal pregnancy are incompletely understood, and even less understood is the question of how this system may be altered and contribute to the hypertensive disorders of pregnancy. Findings from our group have provided novel insights into how the RAS may contribute to the physiological condition of pregnancy by showing that pregnancy increases the expression of both the vasodilator heptapeptide of the RAS, angiotensin-(1-7) [Ang-(1-7)], and of a newly cloned angiotensin converting enzyme (ACE) homolog, ACE2, that shows high catalytic efficiency for Ang II metabolism to Ang-(1-7). The discovery of ACE2 adds a new dimension to the complexity of the RAS by providing a new arm that may counter-regulate the activity of the vasoconstrictor component, while amplifying the vasodilator component. The studies reviewed in this article demonstrate that Ang-(1-7) increases in plasma and urine of normal pregnant women. In preeclamptic subjects we showed that plasma Ang-(1-7) was suppressed as compared to the levels found in normal pregnancy. In addition, kidney and urinary levels of Ang-(1-7) were increased in pregnant rats coinciding with the enhanced detection and expression of ACE2. These findings support the concept that in normal pregnancy enhanced ACE2 may counteract the elevation in tissue and circulating Ang II by increasing the rate of conversion to Ang-(1-7). These findings provide a basis for the physiological role of Ang-(1-7) and ACE2 during pregnancy.

Renin-secreting tumor. Case report.

Renin-secreting tumor, though rare, should be considered in assessing severe hyperreninemic, hypertensive patients. We studied an 18-year-old girl with hypokalemic hyperreninemic hyperaldosteronism. No angiographic lesion could be detected. The plasma renin activity (PRA) of the right/left renal vein was 7.3. With a presumptive diagnosis of renin-secreting tumor (RST), the patient was operated on, and a cortical nodule was found on the right lower pole. Partial nephrectomy was followed by a rapid fall in PRA (half-life, 33-44 min) and normalization of blood pressure (BP). At 3 1/2 months postoperatively, the patient showed normotension, normokalemia, normal aldosterone, and slightly elevated PRA unresponsive to postural changes and furosemide treatment. Tumoral PRA secretion responded to postural stimulus, spironolactone use, and nitroprusside-induced hypotension. Neither the high aldosterone excretion nor hyperreninemia decreased after 3 days of DOCA; this agrees with a previously reported case suggesting the usefulness of this test in the diagnosis of RST.

Tissue kallikrein and bradykinin B2 receptor in human uterus in luteal phase and in early and late gestation

This study was addressed to evaluate the temporospatial pattern of key components of the kallikreinkinin system in human uterus in luteal phase (n=7), early pregnancy (isolated spontaneous abortions, n = 11; ectopic pregnancies, n=9), idiopathic preterm deliveries (n=5), and term gestations (n=12). Tissue kallikrein mRNA and protein and the type 2 bradykinin receptor (B2R) protein were expressed in luminal and glandular epithelium and in endothelial cells of stromal and myometrial blood vessels, while tissue kallikrein mRNA and B2R, but not tissue kallikrein protein, were observed in decidual cells and in arteriolar and myometrial muscle. A greater signal intensity for tissue kallikrein mRNA and protein and of B2R protein was observed in the early pregnancy samples. The sites and variations of the tissue kallikrein mRNA and protein and of the B2R protein in the human uterus and in fallopian tubes during the luteal phase and in pregnancy coincide with those described for other vasoactive effectors such as nitric oxide, prostacyclins, growth factors, and renin. The uterine localization of the main enzyme and receptor of the tissue kallikrein-kinin system in key sites for embryo attachment, implantation, placentation, maintenance of placental blood flow, and parturition supports the notion that the kallikrein-kinin system participates in these processes, probably through vasodilation, increased vasopermeability, enhanced matrix degradation, stimulation of cell proliferation, and myometrial contractility.

Expression of kallikrein, bradykinin B2 receptor, and endothelial nitric oxide synthase in placenta in normal gestation, preeclampsia, and placenta accreta

In an effort to define the varied expression of three vasoactive markers in the clinical models of normal placenta/normal invasion (n=11), preeclampsia/restricted trophoblast invasion (n=15), and placenta accreta/exaggerated invasion (n=6), we performed semiquantitative immunohistochemistry for kallikrein, bradykinin B2 receptor, and endothelial nitric oxide synthase (eNOS). In the floating villi, the syncytiotrophoblast expressed more kallikrein in placenta accreta (p<0.05), than in normal and preeclamptic placentas, while the bradykinin B2 receptor and eNOS were similarly expressed in all groups; in the fetal endothelium, the bradykinin B2 receptor was enhanced in placenta accreta (p<0.005), but kallikrein and eNOS were similarly expressed in the other two groups. In the extravillous trophoblast, both kallikrein and eNOS expression were higher in placenta accreta (p<0.001), while the bradykinin B2 receptor signal was only enhanced in preeclampsia (p<0.05). The presence and localization of kallikrein, the bradykinin B2 receptor, and eNOS in the fetomaternal interface in the three study conditions supports a local role for interrelated vasodilatory/antiaggregating systems. This first report of the variations observed in kallikrein and eNOS in a condition of exaggerated trophoblast invasion supports the participation of vasodilatation in trophoblast migration.

Spatio-temporal expression of MMP-2, MMP-9 and tissue kallikrein in uteroplacental units of the pregnant guinea-pig (Cavia porcellus)

BackgroundIn humans trophoblast invasion and vascular remodeling are critical to determine the fate of pregnancy. Since guinea-pigs share with women an extensive migration of the trophoblasts through the decidua and uterine arteries, and a haemomonochorial placenta, this species was used to evaluate the spatio-temporal expression of three enzymes that have been associated to trophoblast invasion, MMP-2, MMP-9 and tissue kallikrein (K1).MethodsUteroplacental units were collected from early to term pregnancy. MMP-2, MMP-9 and K1 were analysed by immunohistochemistry and Western blot. The activities of MMP-2 and MMP-9 were assessed by gelatin zymography.ResultsImmunoreactive MMP-2, MMP-9 and K1 were detected in the subplacenta, interlobar and labyrinthine placenta, syncytial sprouts and syncytial streamers throughout pregnancy. In late pregnancy, perivascular or intramural trophoblasts expressed the three enzymes. The intensity of the signal in syncytial streamers was increased in mid and late pregnancy for MMP-2, decreased in late pregnancy for MMP-9, and remained stable for K1. Western blots of placental homogenates at days 20, 40 and 60 of pregnancy identified bands with the molecular weights of MMP-2, MMP-9 and K1. MMP-2 expression remained constant throughout gestation. In contrast, MMP-9 and K1 attained their highest expression during midgestation. Placental homogenates of 20, 40 and 60 days yielded bands of gelatinase activity that were compatible with MMP-2 and MMP-9 activities. ProMMP-2 and MMP-9 activities did not vary along pregnancy, while MMP-2 and MMP-9 increased at 40 and 40–60 days respectively.ConclusionThe spatio-temporal expression of MMPs and K1 supports a relevant role of these proteins in trophoblast invasion, vascular remodeling and placental angiogenesis, and suggests a functional association between K1 and MMP-9 activation.

Minoxidil in Breast Milk

Excerpt To the editor: Minoxidil is a potent vasodilator used in the treatment of severe hypertension (1). No pregnancies have been reported in patients receiving the drug. We report the case of a ...

Angiogenic, hyperpermeability and vasodilator network in utero-placental units along pregnancy in the guinea-pig (Cavia porcellus).

BackgroundThe angiogenic and invasive properties of the cytotrophoblast are crucial to provide an adequate area for feto-maternal exchange. The present study aimed at identifying the localization of interrelated angiogenic, hyperpermeability and vasodilator factors in the feto-maternal interface in pregnant guinea-pigs.MethodsUtero-placental units were collected from early to term pregnancy. VEGF, Flt-1, KDR, B2R and eNOS were analyzed by immunohistochemistry, and the intensity of the signals in placenta and syncytial streamers was digitally analysed. Flt1 and eNOS content of placental homogenates was determined by western blotting. Statistical analysis used one-way analysis of variance and Tukeys Multiple Comparison post-hoc test.ResultsIn the subplacenta, placental interlobium and labyrinth VEGF, Flt-1, KDR, B2R and eNOS were expressed in all stages of pregnancy. Syncytial streamers in all stages of gestation, and cytotrophoblasts surrounding myometrial arteries in early and mid pregnancy – and replacing the smooth muscle at term – displayed immunoreactivity for VEGF, Flt-1, KDR, eNOS and B2R. In partly disrupted mesometrial arteries in late pregnancy cytotrophoblasts and endothelial cells expressed VEGF, Flt-1, KDR, B2R and eNOS. Sections incubated in absence of the first antibody, or in presence of rabbit IgG fraction and mouse IgG serum, yielded no staining. According to the digital analysis, Flt-1 increased in the placental interlobium in days 40 and 60 as compared to day 20 (P = 0.016), and in the labyrinth in day 60 as compared to days 20 and 40 (P = 0.026), while the signals for VEGF, KDR, B2R, and eNOS showed no variations along pregnancy. In syncytial streamers the intensity of VEGF immunoreactivity was increased in day 40 in comparison to day 20 (P = 0.027), while that of B2R decreased in days 40 and 60 as compared to day 20 (P = 0.011); VEGF, Flt-1, KDR, B2R and eNOS expression showed no variations. Western blots for eNOS and Flt-1 in placental homogenates showed no significant temporal differences along pregnancy.ConclusionThe demonstration of different angiogenic, hyperpermeability and vasodilator factors in the same cellular protagonists of angiogenesis and invasion in the pregnant guinea-pig, supports the presence of a functional network, and strengthens the argument that this species provides an adequate model to understand human pregnancy.