Endothelial function in myometrial resistance arteries of normal pregnant women perfused with syncytiotrophoblast microvillous membranes.

OBJECTIVE: To investigate the effects of syncytiotrophoblast microvillous membranes (STBM) in concentrations, found in vivo in women with pre-eclampsia, on endothelial function in isolated resistance arteries. SETTING: Department of Obstetrics and Gynaecology, Huddinge University Hospital, Stockholm. SAMPLE: Twenty-nine myometrial resistance arteries isolated from biopsies of healthy term pregnant women, obtained during caesarean section. METHODS: The myometrial arteries were mounted in a pressure arteriograph and perfused intraluminally for three hours with STBM (20 to 2000ng/mL) or with erythrocyte membranes or physiological salt solution as controls, all substituted with 0.5% bovine serum albumin. Bradykinin concentration-response curves were performed before and after perfusion. MAIN OUTCOME MEASURES: The bradykinin concentrationresponse curves were fitted to the Hill equation and maximal dilation and the pEC50 values were determined from these fits. Differences within groups were analysed with a paired Student's t test. Electron microscopic evaluation of the endothelium was performed. RESULTS: Neither STBM nor erythrocyte membrane perfusion affected maximal dilation or the pEC50 values of the bradykinin concentration-response curves at any concentration. Examination by electron microscopy showed no obvious damage to the endothelium after perfusion with STBM or erythrocyte membranes. CONCLUSION: Perfusion with STBM in concentrations up to 100 times those reported in pre-eclampsia has no significant effect on bradykinin-mediated dilation in isolated myometrial arteries.

Expression of inflammatory cytokines in placentas from women with preeclampsia.

It is postulated that inadequate remodeling of the uterine spiral arteries in preeclampsia leads to focal ischemia and generation of inflammatory cytokines, such as tumor necrosis factor (TNF alpha) and interleukins (ILs), by the placenta. Our objective was to compare TNF alpha, IL-1 alpha, IL-1 beta, and IL-6 levels in placentas from patients with preeclampsia and normal term pregnancies. Because the placenta is a large heterogeneous organ, we analyzed multiple sites per placenta. On the average, there was a 3-fold variation in cytokine protein levels across the eight sites analyzed for each placenta. However, there were no significant overall differences among the normal term, preeclamptic, and preterm placentas from women without preeclampsia. There were also no significant differences in TNF alpha messenger ribonucleic acid between the normal term and preeclamptic placentas, although TNF alpha messenger ribonucleic acid levels were lower in placentas from preterm patients without diagnosis of preeclampsia than in the normal term placentas. In vitro, hypoxia stimulated the production of TNF alpha, IL-1 alpha and IL-1 beta, but not that of IL-6, by placental villous explants from both groups of patients, and this was not exaggerated in preeclampsia. Finally, although peripheral and uterine venous levels of TNF alpha were elevated in preeclamptic women compared with normal term patients, the ratio of uterine to peripheral venous TNF alpha levels was not significantly different from 1.0 for either patient group. Taken together, these results suggest that sources other than the placenta contribute to the elevated concentrations of TNF alpha and IL-6 found in the circulation of preeclamptic women.

Up-regulation of p21- and RhoA-activated protein kinases in human pregnant myometrium.

The role of small ras homologous GTP-binding proteins in the regulation of smooth muscle contractility has become increasingly apparent but there is still little information about the presence of these proteins in human uterine smooth muscle. Messenger RNAs for p21-activated protein kinase isoforms (PAK1, PAK2, and PAK3) were detectable in both nonpregnant and pregnant human myometrial tissue. However, PAK3 protein was not detectable and the proteins for PAK1 and PAK2 were only detectable in pregnant tissue. Moreover there was a large increase in the constitutively active p34 protein fragment of PAK2 in pregnant tissue. Protein expression of RhoA-activated protein kinases isoforms (ROK1 and ROK2) also increased during pregnancy. Stimulation of RhoA signaling in pregnant myometrial tissue with lysophosphatic acid (LPA) increased the level of myosin light chain (MLC20) phosphorylation. Preincubation of the tissue with C3 toxin inhibited LPA-stimulated MLC20 phosphorylation and lowered the basal phosphorylation level of MLC20. Thus ROKS and PAKS have the potential to regulate uterine contractility and/or load-bearing during human pregnancy.

Spinal cord insults in the prenatal, perinatal, and neonatal periods.

We investigated the features of children with spinal cord insults (SCI) occurring in the pre-, peri-, and neonatal periods by sending 340 questionnaires to all paediatric neurologists, paediatric urologists, and neonatologists in the UK and Ireland. We requested information about timing, nature, and level of SCI in their patients; family and maternal history; pregnancy, delivery, and neonatal period; clinical presentation, imaging, laboratory studies, and outcome. Two-hundred and sixty-one questionnaires were returned with data on 58 patients with SCI. Seven out of the 58 children with SCI had pure dysraphic cord syndromes and were excluded. Fifty-one patients (33 males, 17 females, one unknown), born between 1972 and 1996, remained. Clinical presentations included severe respiratory failure (N=20; five of whom died neonatally) and hypotonia or weakness recognized either during the neonatal period (N=12) or after 28 days (N=10). Data on clinical presentation were not given in nine cases. Lesions were cervical (N=22) and thoraco-lumbar (N=29). SCI was ascribed to ischaemia (N=12), trauma (N=4), and other associated underlying conditions (N=11), whilst the aetiology was unknown in 24 cases. Mean gestational age (36.2 weeks) and birthweight (2.6 kg) were lower than previously reported with the lowest figures associated with thoraco-lumbar and ischaemic lesions. More males were affected by lesions than females and the incidence of preterm delivery, multiple pregnancy, breech presentation, forceps delivery, and caesarean delivery were higher than average. Forceps delivery was associated with cervical lesions. Outcome data were given in 47 children, nine of whom died either neonatally or within the first 20 months of life. Motor disability ranged from a complete recovery in one out of 40 to paraparesis in 26 out of 40, and tetraparesis in 13 out of 40 patients: 17 out of 39 were ambulant. Sphincter dysfunction was present in 22 out of 38 patients and scoliosis in 16 out of 37. Learning difficulties were present in 10 out of 39, behavioural problems in five out of 39 and seizures in four out of 39 patients. SCI in the pre-, peri-, and neonatal periods are rare but probably under-diagnosed and are heterogeneous in aetiology, presentation, and outcome. Boys appear to be more susceptible than girls.

Elevated levels of serum nitrate, a stable end product of nitric oxide, in women with pre-eclampsia.

OBJECTIVES: Nitric oxide released from vascular endothelial cells is a potent vasodilator and inhibits platelet adhesion. It has been suggested that decreased nitric oxide production from dysfunctional endothelial cells is implicated in the pathophysiology of pre-eclampsia. In this study evidence was sought for abnormal production of nitric oxide in pre-eclamptic women. PARTICIPANTS: Blood was collected from 20 women presenting with pre-eclampsia, from 20 matched healthy pregnant controls and from 12 nonpregnant women of childbearing age. METHODS: Serum nitrate, the stable end metabolite of nitric oxide, was measured by vanadium III chloride reduction and chemiluminescence. RESULTS: Sera from women with pre-eclampsia had significantly higher nitrate concentrations (mean 47.4 mumol/L [SD 13.6]) compared with healthy pregnant (mean 31.2 mumol/L [SD 9.14]) and nonpregnant (mean 32.1 mumol/L [SD 10.0]) controls. CONCLUSIONS: These results do not support the hypothesis that decreased endothelial cell nitric oxide production may be important in the pathophysiology of pre-eclampsia. On the contrary, serum nitrate levels are increased which may reflect either increased production of nitric oxide from an unidentified source or decreased elimination through the kidneys.

Human placental syncytiotrophoblast microvillous membranes impair maternal vascular endothelial function.

OBJECTIVE: To investigate the hypothesis that, should there be an increase in deported syncytiotrophoblast microvillous membrane fragments in pre-eclampsia, it may cause maternal vascular endothelial dysfunction. DESIGN: Syncytiotrophoblast microvillous membrane (STBM) vesicles, prepared from normal term placentae, were perfused through small subcutaneous arteries isolated from fat biopsies obtained at caesarean section. Endothelial function of these arteries was studied by determining acetylcholine-induced relaxation after preconstriction with noradrenaline. As controls, physiological buffer or red blood cell membranes in physiological buffer were used and endothelial function similarly estimated. Transmission electron microscopy was performed on arteries after perfusion. SAMPLE: STBM vesicles, isolated from the placentae of three healthy women undergoing elective caesarean section for reasons unrelated to pre-eclampsia, were suspended in physiological buffer. Subcutaneous fat arteries were obtained from a separate group of 13 normotensive pregnant women, also undergoing elective caesarean section at term. RESULTS: Perfusion with red blood cell membranes or physiological buffer had no significant effect on the concentration dependent relaxation in arteries preconstricted with noradrenaline. However, after 2 h perfusion with STBM vesicles, arteries showed a significant reduction in relaxation to acetylcholine, indicative of altered endothelial function. Transmission electron microscopy of arteries perfused with STBM vesicles confirmed endothelial disruption. CONCLUSIONS: STBM vesicle perfusion specifically altered the relaxation response of preconstricted maternal subcutaneous fat arteries to acetylcholine, suggesting an alteration in endothelial dependent relaxation. Deported microvilli may therefore be capable of producing endothelial cell damage and endothelial dysfunction observed in the maternal syndrome of pre-eclampsia.

Endothelial cell proliferation is suppressed by plasma but not serum from women with preeclampsia.

OBJECTIVES: Evidence has been sought for a circulating factor derived from the placenta that suppresses endothelial cell proliferation and hence contributes to the maternal endothelial cell disturbances of preeclampsia. STUDY DESIGN: The effects of sera and plasmas from women with proteinuric preeclampsia and from matched normal pregnant control women on endothelial cell proliferation were compared. The recovery of endothelial cell inhibitory activity from syncytiotrophoblast microvesicles added to male blood and prepared as plasma or serum was determined to investigate the possible placental origin of the inhibitory factor. RESULTS: Sera from women with preeclampsia did not inhibit endothelial cell proliferation. In contrast, plasma from preeclamptic women significantly suppressed endothelial cell growth at 20% dilution compared with controls, and suppression was more pronounced in severe preeclampsia. The inhibitory activity of syncytiotrophoblast microvesicles added to blood could not be recovered from serum, only from plasma, which may explain why there was no suppression with sera from preeclamptic women. CONCLUSIONS: These results confirm that there is a blood-borne endothelial cell suppressive factor in preeclampsia that may be derived from the placenta.

The effect of placental syncytiotrophoblast microvillous membranes from normal and pre-eclamptic women on the growth of endothelial cells in vitro.

OBJECTIVES: To determine if placental syncytiotrophoblast microvillous (STBM) membranes contain factors which could cause the maternal endothelial cell disturbance thought to be central to the pathophysiology of the maternal syndrome of pre-eclampsia. DESIGN: STMB membranes isolated from pre-eclamptic or normal placentae were added to cultures of endothelial cells and their effect on the proliferation (measured by 3H-thymidine incorporation), viability (measured by 51Cr release) and growth as a monolayer of these cells was determined. Membranes prepared from red blood cells, and non-endothelial adherent and nonadherent cell lines were used as specificity controls. SUBJECTS: STBM membranes were isolated from the placentae of primigravid women, 10 having caesarean sections for breech presentations and 10 for pre-eclampsia. RESULTS: STBM membranes from the placentae of normal and pre-eclamptic women suppressed endothelial cell proliferation to a similar extent and disrupted the cell monolayer to form a honeycomb-like pattern. This change in morphology was seen before significant endothelial cell death occurred. Red blood cell membranes had no effect on either endothelial cell proliferation, viability or monolayer integrity. Endothelial cells from human umbilical arteries and bovine adrenal capillaries were similarly suppressed, but comparable concentrations of STBM membranes had no effect on non-endothelial cell lines. CONCLUSIONS: Syncytiotrophoblast microvillous membranes specifically interfered with endothelial cell growth in vitro. Our results demonstrate that there are trophoblast products which could cause the maternal syndrome of pre-eclampsia through endothelial cell damage.

Monocytosis and monocytic infiltration of decidua in early pregnancy.

This study showed a marked increase of blood monocytes in the 7th-20th week of pregnancy. The highest monocyte values were observed in the very first weeks whereas neutrophil counts were increasing throughout the observation period. No significant pregnancy associated changes were found in T-cell subpopulations or in HLA-DR expression by monocytes. First trimester decidual tissue contained many HLA-DR, Leu-M3 positive cells. Their distribution was patchy and mainly confined to areas of prominent decidual reaction. In contrast normal secretory phase endometrium showed only occasional Leu-M3, HLA-DR positive cells but a few clusters of glandular epithelial cells expressed HLA-DR. Culture supernatants from both decidual and secretory endometrial tissues contained PGE2 in concentrations known to suppress PHA lymphocyte responses in vitro. We postulate that monocytes infiltrating the decidual tissue may, possibly through PGE2 mediated immunosuppression, help to prevent rejection of the fetal allograft early in pregnancy.