Increased neutrophil-endothelial adhesion induced by placental factors is mediated by platelet-activating factor in preeclampsia

Platelets and endothelial dysfunction in gestational diabetes mellitus

The prevalence of gestational diabetes mellitus (GDM) has increased in recent years, along with the higher prevalence of obesity in women of reproductive age. GDM is a pathology associated with vascular dysfunction in the fetoplacental unit. GDM-associated endothelial dysfunction alters the transfer of nutrients to the foetus affecting newborns and pregnant women. Various mechanisms for this vascular dysfunction have been proposed, of which the most studied are metabolic alterations of the vascular endothelium. However, different cell types are involved in GDM-associated endothelial dysfunction, including platelets. Platelets are small, enucleated cell fragments that actively take part in blood haemostasis and thrombus formation. Thus, they play crucial roles in pathologies coursing with endothelial dysfunction, such as atherosclerosis, cardiovascular diseases, and diabetes mellitus. Nevertheless, platelet function in GDM is understudied. Several reports show a potential relationship between platelet volume and mass with GDM; however, platelet roles and signaling mechanisms in GDM-associated endothelial dysfunction are unclear. This review summarizes the reported findings and proposes a link among altered amount, volume, mass, reactivity, and function of platelets and placenta development, resulting in fetoplacental vascular dysfunction in GDM.

Preeclampsia Status Controls Interleukin-6 and Soluble IL-6 Receptor Release from Neutrophils and Endothelial Cells: Relevance to Increased Inflammatory Responses

Increased neutrophil–endothelial binding and inflammatory responses are significant pathophysiological events in the maternal vascular system in preeclampsia, a hypertensive disorder in human pregnancy. Interleukin 6 (IL-6) and its soluble receptors (soluble IL-6R (sIL-6R) and soluble gp130 (sgp130)) are critical inflammatory mediators. During pregnancy, maternal IL-6 and sgp130 levels were increased, but sIL-6R levels were decreased, in women with preeclampsia compared to normotensive pregnant women. However, little is known about differences in IL-6, sIL-6R, and sgp130 production by neutrophils and endothelial cells between normal pregnancy and preeclampsia. To study this, we isolated neutrophils and cultured human umbilical vein endothelial cells (HUVECs) from normal and preeclamptic pregnancies. Production of IL-6, sIL-6R, and sgp130 was measured. The role of placental factor(s)-mediated neutrophil production of IL-6, sIL-6R, and sgp130 was also determined by pretreating neutrophils with placental conditioned medium generated from placental villous cultures. We found that IL-6 and sgp130 were mainly produced by endothelial cells, while sIL-6R was mainly produced by neutrophils. Endothelial cells from preeclampsia produced significantly more IL-6 and sgp130, and neutrophils from preeclampsia produced significantly less sIL-6R than normal pregnancy cells. Interestingly, production of IL-6, sIL-6R, and sgp130 were time-dependently increased when neutrophils and endothelial cells were co-cultured. We also found that neutrophils from normal pregnancies produced more IL-6, but less sIL-6R, after being primed by preeclamptic-placental conditioned medium. These results demonstrated that neutrophils and endothelial cells have different capacities in producing IL-6, sIL-6R, and sgp130 between normal pregnancy and preeclampsia. These results also provide evidence that the placenta plays a role in inducing neutrophil activation in preeclampsia.

IL-36 Cytokines: Regulators of Inflammatory Responses and Their Emerging Role in Immunology of Reproduction

The IL-36 subfamily of cytokines has been recently described as part of the IL-1 superfamily. It comprises three pro-inflammatory agonists (IL-36α, IL-36β, and IL-36γ), their receptor (IL-36R), and one antagonist (IL-36Ra). Although expressed in a variety of cells, the biological relevance of IL-36 cytokines is most evident in the communication between epithelial cells, dendritic cells, and neutrophils, which constitute the common triad responsible for the initiation, maintenance, and expansion of inflammation. The immunological role of IL-36 cytokines was initially described in studies of psoriasis, but novel evidence demonstrates their involvement in further immune and inflammatory processes in physiological and pathological situations. Preliminary studies have reported a dynamic expression of IL-36 cytokines in the female reproductive tract throughout the menstrual cycle, as well as their association with the production of immune mediators and cellular recruitment in the vaginal microenvironment contributing to host defense. In pregnancy, alteration of the placental IL-36 axis has been reported upon infection and pre-eclampsia suggesting its pivotal role in the regulation of maternal immune responses. In this review, we summarize current knowledge regarding the regulatory mechanisms and biological actions of IL-36 cytokines, their participation in different inflammatory conditions, and the emerging data on their potential role in normal and complicated pregnancies.

Up-regulation of miR-203 expression induces endothelial inflammatory response: Potential role in preeclampsia

PROBLEM

To determine whether miR-203 mediates endothelial inflammatory response in preeclampsia.

METHOD OF STUDY

Maternal vessel miR-203 expression was assessed by in situ hybridization. Suppressor of cytokine signaling-3 (SOCS-3) and ICAM expression was determined by immunostaining. Subcutaneous fat tissue sections from normal and preeclamptic pregnant women were used. miR-203-induced inflammatory response was evaluated by the measurements of IL-6, IL-8, ICAM, and VCAM expression and production and neutrophil adhesion in the endothelial cells (EC) transfected with miR-203 precursor, pre-miR-203. SOCS3 expression was also determined.

RESULTS

Up-regulation of miR-203 and ICAM expression and down-regulation of SOCS-3 expression were demonstrated in maternal vessel endothelium in preeclampsia. Overexpression of miR-203 resulted in down-regulation of SOCS-3 expression and increases in the production of IL-6, IL-8, ICAM, and VCAM and neutrophil adhesion in ECs.

CONCLUSION

As miR-203 is an inflammatory microRNA, increased miR-203 production/expression in ECs could diminish an anti-inflammatory activity and increase the endothelial inflammatory response in preeclampsia.

Neonatal Thrombocytopenia as a Consequence of Maternal Preeclampsia

Introduction Preeclampsia (preE) is pregnancy-induced hypertension affecting a significant proportion of pregnant women worldwide and can cause detrimental effects in the mother and newborn. Some of the effects in the newborn include neonatal thrombocytopenia. Pertaining specifically to neonatal thrombocytopenia, several questions remain unanswered. Discussion According to the current literature, neonatal thrombocytopenia due to maternal preE is highly prevalent in the general population and the incidence is reported to be around 30% worldwide. This review gives an insight into the syndrome and summarizes the possible pathological mechanisms, the diagnostic approach, complications, and therapeutic interventions of neonatal thrombocytopenia. It also identifies the involvement of other cell lines, apart from platelets in the newborns. Furthermore, we suggest a future prospective study to investigate the pathogenesis of preE and plan a study involving animal models to come up with a possible therapeutic intervention to prevent preE and its various consequences in neonates.

PAR-2 triggers placenta-derived protease-induced altered VE-cadherin reorganization at endothelial junctions in preeclampsia

PAR-2 is a G-protein coupled protease receptor whose activation in endothelial cells (ECs) is associated with increased solute permeability. VE-cadherin is an endothelial-specific junction protein, which exhibits a disorganized distribution at cell junction during inflammation and is a useful indicator of endothelial barrier dysfunction. In the present study, we tested the hypothesis that PAR-2 activation mediates placenta-derived chymotrypsin-like protease (CLP)-induced endothelial junction disturbance and permeability in preeclampsia (PE). PAR-2 and VE-cadherin were examined by immunofluorescent staining. Specific CLP induced PAR-2 activation and altered VE-cadherin distribution was assessed following depletion of protease chymotrypsin in the placental conditioned medium and after PAR-2 siRNA. VE-cadherin assembly was determined by treating cells with protease chymotrypsin and/or the specific PAR-2 agonist SLIGKV-NH2. Our results showed: 1) placental conditioned medium not only disturbed VE-cadherin distribution at cell junctions but also activated PAR-2 in ECs; 2) PAR-2 siRNA blocked the placental conditioned medium induced PAR-2 upregulation and disorganization of VE-cadherin at cell junctions; 3) PAR-2 agonist induced PAR-2 activation and VE-cadherin reorganization were dose-dependent; and 4) PAR-2 agonist could stimulate ERK1/2 activation. These results strongly suggest that proteases produced by the placenta elicit endothelial barrier dysfunction via a PAR-2 signaling regulatory mechanism in PE.

Elevated maternal soluble Gp130 and IL-6 levels and reduced Gp130 and SOCS-3 expressions in women complicated with preeclampsia

Increased inflammatory response plays a significant role in the vascular pathophysiology in preeclampsia. However, the mechanism for increased inflammatory response in preeclampsia is largely unknown. Interleukin (IL)-6 levels are elevated in women with preeclampsia. IL-6 and its receptors, IL-6R and glycoprotein (gp)130, play a critical role in mediating antiinflammatory response via induction of SOCS-3 (suppressor of cytokine signaling-3). However, IL-6 receptor levels and expressions have not been studied in preeclampsia. In this study, we measured IL-6 and its 2 soluble receptors, soluble IL-6R and soluble gp130, in maternal plasma from normal and preeclamptic pregnant women and found that not only IL-6 but also soluble gp130 levels were significantly higher in preeclamptic women than in normotensive pregnant controls. We further examined IL-6R, gp130, and SOCS-3 expressions in maternal vessels and leukocytes and found that gp130 and SOCS-3 expressions were downregulated in both vessel endothelium and leukocytes from preeclampsia. Different patterns for IL-6R and gp130 expressions were found. IL-6R expression was also downregulated in leukocytes from preeclampsia. Our results suggest that increased plasma soluble gp130/soluble IL-6R/IL-6 ratio and reduced membrane transsignaling gp130 expression could contribute to decreased SOCS-3 expression and subsequent reduction in SOCS-3 antiinflammatory activity in women with preeclampsia. Thus, reduced gp130 and SOCS-3 expressions may offer, at least in part, a plausible explanation of reduced antiinflammatory protection in the maternal vascular system in preeclampsia.

Inhibition of VEGF or TGF-{beta} signaling activates endothelium and increases leukocyte rolling

OBJECTIVE

Motivated by the central roles that vascular endothelial growth factor (VEGF) and transforming growth factor (TGF)-beta play in the assembly and maintenance of the vasculature, we examined the impact of systemic VEGF or TGF-beta signal inhibition on endothelial activation as detected by leukocyte-endothelial interactions.

METHODS AND RESULTS

VEGF or TGF-beta inhibition, accomplished using adenovirus expression of soluble Flt1 (Ad-sFlt1) or soluble endoglin (Ad-sEng), resulted in a significant increase in the number of leukocytes rolling along the mesenteric venous endothelium and a significant decrease in rolling velocity in Ad-sEng mice. Neutralization of VEGF or TGF-beta resulted in endothelial surface expression of P-selectin and impaired peripheral vasodilatation. Neither inhibition of VEGF nor TGF-beta was associated with platelet or leukocyte activation, as detected by the activation markers platelet P-selectin and the active integrin alphaIIbbetaIII, or by leukocyte expression of L-selectin. Soluble vascular cell adhesion molecule (VCAM)-1 and E-selectin were increased in sEng-expressing mice, indicating higher levels of these adhesion receptors.

CONCLUSIONS

VEGF or TGF-beta neutralization leads to impaired endothelium-mediated vasodilatation and elevated expression of surface adhesion molecules, resulting in increased leukocyte adhesion. These results indicate an essential role for both VEGF and TGF-beta in maintaining the endothelium in a nonactivated state and have implications for therapeutic approaches that neutralize VEGF or TGF-beta.

Chymotrypsin-like protease (chymase) mediates endothelial activation by factors derived from preeclamptic placentas

Endothelial cells (EC) activation is an important inflammatory phenotypic change in the vascular system in women with preeclampsia (PE). In PE, maternal vessel chymotrypsin-like protease (CLP)/chymase expression was increased. Chymase is an inflammatory protease. In this study, we specifically examined whether placental-derived CLP could induce EC activation and whether EC activation is associated with increased cellular protease expression. Human uterine microvascular endothelial cells (UtMVECs) were used. Endothelial activation was determined by endothelial adhesion molecule P-selectin, E-selectin, inter-cellular adhesion molecule (ICAM), and vascular cell adhesion molecule (VCAM) expressions and by extracellular regulated kinase (ERK) activity. Activation of endogenous CLP/chymase associated with ERK phosphorylation was further examined by CLP/chymase short interfering RNA (siRNA). Our results showed that cells treated with PE placental conditioned medium revealed increased P-selectin, E-selectin, and VCAM-1 expressions and increased ERK phosphorylation. Increased endothelial adhesion molecule expression and phosphorylated ERK (pERK) induction could be attenuated or abolished by depletion of CLP in the conditioned medium or by transfecting ECs with CLP/chymase siRNA. These observations suggest that placental-derived CLP/chymase is responsible for inducing endothelial inflammatory phenotypic changes possibly by upregulation of cell adhesion molecule expressions, activation of cellular protease, and induction of ERK phosphorylation. We speculate that activation of endothelial CLP/chymase may directly relate to the increased inflammatory phenotypic changes in the vascular system in women with PE.

Marinobufagenin causes endothelial cell monolayer hyperpermeability by altering apoptotic signaling

Marinobufagenin (MBG) is an endogenous mammalian cardiotonic steroid that is involved in the inhibition of the sodium pump Na(+)/K(+)-ATPase. Increased plasma levels of MBG have been reported in patients with preeclampsia. MBG increases microvascular barrier permeability in an animal model of preeclampsia. However, the mechanism by which MBG impairs endothelial permeability is unknown. We utilized rat lung microvascular endothelial cells (RLMEC) to examine alterations in MBG-induced monolayer permeability and the effect of MBG on the phosphorylation status of ERK1/2, Jnk, and p38. Apoptosis was evaluated by examining alterations in caspases 3/7, 8, and 9 and annexin-V staining. We also examined the effect of MBG on the endothelial adherens junctions of the RLMEC monolayer. MBG inhibited the proliferation, and increased the monolayer permeability, of RLMEC. These actions of MBG were attenuated by ERK, p38, and pan caspase inhibition. MBG significantly decreased the phosphorylation of ERK1/2 and activated the phosphorylation of Jnk and p38. MBG also significantly increased the expression of caspases 3/7, 8, and 9, indicating the activation of apoptosis. MBG-induced apoptosis signaling was not observed in cells pretreated with a p38 inhibitor. MBG treatment induced the disruption of endothelial cell junctions. This effect was prevented by a pan caspase inhibitor. In conclusion, 1) MBG induced an impairment of RLMEC proliferation; 2) the bufadienolide also caused endothelial hyperpermeability; and 3) these effects of MBG were mediated by the downregulation of ERK1/2, the upregulation of Jnk and p38, by the activation of apoptosis, and by the disruption of endothelial cell junctions.

Endothelial angiotensin II generation induced by placenta-derived factors from preeclampsia

Hypersensitivity to angiotensin II contributes to the increased vasoconstriction in preeclampsia. In this study, we determined whether placenta-derived factors could affect endothelial cell angiotensin II generation.Our results showed that more angiotensin II was produced by endothelial cells treated with preeclampsia placental conditioned medium than the cells treated with normal conditioned medium or untreated controls. To determine which pathway, angiotensin-converting enzyme or nonangiotensin-converting enzyme angiotensin-generating enzyme/chymase, might be involved in preeclampsia conditioned medium induced angiotensin II generation, angiotensin-converting enzyme inhibitor captopril and chymotrypsin inhibitors were applied to the cell culture either separately or in combination. We found that chymotrypsin inhibitor, but not captopril, could attenuate the increased angiotensin II generation. To further test specific effects of the protease on endothelial cell angiotensin II generation, endothelial cells were grown in cell culture inserts and chymotrypsin was added to the upper chamber of the cell culture (apical exposure). The medium in the lower chamber (basal direction) was collected and measured for angiotensin II. Our results showed that apical exposure of endothelial cells to the protease resulted in a concentration-dependent increase in basal release of angiotensin II. Angiotensin II receptor-1 expression was also upregulated in cells treated with preeclampsia conditioned medium or chymotrypsin. This data suggest that placenta-derived factors may activate chymase-angiotensin pathway in endothelial cells. Moreover, increased endothelial cell basal release of angiotensin II in response to the protease stimulation further suggests that angiotensin II levels in the circulation may not necessarily reflect angiotensin II generation within the vascular wall.

Placenta-derived chymotrypsin-like protease (CLP) disturbs endothelial junctional structure in preeclampsia

Placenta-derived chymotrypsin-like protease may contribute to endothelial activation in preeclampsia. In this study, we determined if placenta-derived chymotrypsin-like protease could disturb endothelial junctional integrity to promote endothelial permeability in preeclampsia. Confluent endothelial cells were cocultured with placental trophoblasts or treated with preeclampsia placenta-conditioned medium. Endothelial junction protein vascular endothelial cadherin expression and distribution were examined by fluorescent staining of endothelial cells with or without depletion of chymotrypsin. The association of endothelial cell junction protein complex VE-cadherin/beta-catenin/p120 was examined by a combined immuno-precipitation and immuno-blotting assay. Our results showed that endothelial cells cocultured with preeclampsia trophoblasts or exposed to preeclampsia placental conditioned medium exhibited a discontinuous distribution and reduced expression of vascular endothelial cadherin at cell contact regions. Vascular endothelial cadherin and p120 were expressed in control endothelial cells, but reduced or lost in endothelial cells exposed to preeclampsia placental conditioned medium, suggesting that the junctional protein complex of VE-cadherin/beta-catenin/p120 was disrupted in endothelial cells exposed to preeclampsia placental conditioned medium. We also observed that removal of trophoblasts from the coculture system and depletion of the protease from the preeclampsia placental conditioned medium could restore the dysregulated endothelial junction protein expression and distribution. Chymotrypsin also induced a dose dependent increase in endothelial monolayer permeability. We conclude that chymotrypsin-like protease released by the placenta is at least one important mediator responsible for disrupting endothelial cell integrity and inducing endothelial permeability in preeclampsia.

Altered interleukin-6 receptor, IL-6R and gp130, production and expression and decreased SOCS-3 expression in placentas from women with pre-eclampsia

Interleukin-6 (IL-6) and its receptor complex, IL-6 receptor (IL-6R) and gp130, are critical in induction of suppressor of cytokine signalling-3 (SOCS-3) protein, a negative cytokine regulator and anti-inflammatory mediator, in a biological system. Increased inflammatory response is believed to contribute to the placental dysfunction in pre-eclampsia (PE). However, it is not known if altered IL-6 receptor signalling and decreased SOCS-3 expression occur in placentas from PE. To study this, we examined IL-6, soluble IL-6R (sIL-6R) and soluble gp130 (sgp130) production by villous tissue from normal and PE placentas. Hypoxia effects on IL-6, sIL-6R and sgp130 production was determined. IL-6R, gp130 and SOCS-3 expression were determined by immunohistochemical staining and by Western blot. Our results showed that under normoxic conditions (21% O(2)), villous tissue from PE placentas produced relative more sgp130, but significantly less IL-6 and sIL-6R (p<0.01) than normal placental tissue. The ratio of sgp130/sIL-6R release was significantly higher by PE placentas than normal placentas, p<0.01. Under hypoxic conditions (2% O(2)), IL-6 production was significantly reduced by both normal (p<0.01) and PE (p<0.05) placental tissue. Hypoxia promoted sgp130 release by normal, but not by PE, placental tissue. Reduced IL-6R and SOCS-3 immunostaining and expression were found in PE placentas. We concluded that increased ratio of sgp130/sIL-6R production and/or reduced sIL-6R production combined with down-regulation of IL-6R and SOCS-3 expression in trophoblasts may lead to less cytokine inhibitory activity in PE placentas, which may account for the increased placental inflammatory response in PE.

Contractility of placental vascular smooth muscle cells in response to stimuli produced by the placenta: roles of ACE vs. non-ACE and AT1 vs. AT2 in placental vessel cells

Our previously published work has shown that non-ACE angiotensin II (Ang II) generating system is dominate in the placenta and may play a critical role in regulation of placental vascular contractile function. In the present study, using a collagen gel contraction assay we further studied contractility of placental vascular smooth muscle cells (VSMCs) in response to factors produced by preeclamptic (PE) placentas. Placental VSMCs/type-1 collagen gels were incubated with PE placental conditioned medium in the presence or absence of inhibitors or receptor blockers. Captopril (an ACE inhibitor), chymostatin (a non-ACE chymase inhibitor), losartan (an AT1 receptor blocker) and PD123,319 (an AT2 receptor blocker) were used to study the specific ACE vs. non-ACE and AT1 vs. AT2 effects on placental VSMC contractility, respectively. Our results showed that chymostatin, but not captopril, and PD123,319, but not losartan, significantly attenuated placental VSMC/collagen gel contraction, p<0.01, respectively. The inhibitory effects of chymostatin and PD123,319 were dose-dependent. Our results suggest that chymase, a non-ACE Ang II generating enzyme, may contribute significantly to Ang II generated in the placenta vascular tissue and that the AT2 receptor may play an important role in the regulation of Ang II induced contractility of placental VSMCs. These results provide new insights into Ang II generation and Ang II receptor regulation of vessel contractile function in the placental vasculature. These results also suggest the potential role of increased chymase activity and altered AT2 receptor function in placental related pregnancy disorders such as preeclampsia and IUGR.

Elevated serum soluble endoglin (sCD105) decreased during extracorporeal elimination therapy for familial hypercholesterolemia

Extracorporeal elimination is a method of LDL-lowering therapy that is used in severe familial hypercholesterolemia (FH) after other therapeutic approaches have failed. There are currently no universally accepted biomarkers that would allow determining necessary intensity of therapy and frequency of future therapeutic interventions. An ideal tool for immediate evaluation would be a readily measurable serum marker. We hypothesized that soluble endoglin (sCD105), a recently described indicator of endothelial dysfunction, may represent such a tool. Eleven patients with FH (three homozygous, eight heterozygous; Fredrickson type IIa, IIb) that have been monitored for 4.5+/-2.8 years were treated; eight by LDL-apheresis and three by hemorheopheresis. 40 sCD105 measurements were done, before and after two consecutive elimination procedures. Baseline serum sCD105 levels were significantly higher in the patients (5.74+/-1.47 microg/l in series I, 6.85+/-1.85 microg/l in series II) than in the control group (3.85+/-1.25 microg/l). They decreased to normal after LDL-elimination (p=0.0003) in all except for one patient. This return to normal was not due to a non-specific capture of endoglin in adsorption or filtration columns as demonstrated by measurement of sCD105 before and after passage through the elimination media. We conclude that the soluble endoglin levels in patients with severe FH remain elevated despite long-term intensive therapy and that they decrease after extracorporeal elimination. Endoglin can therefore serve as a marker for evaluation of the treatment efficacy and of the decreased atherosclerotic activity in patients with FH treated by extracorporeal LDL-cholesterol elimination.

Vasoreactivity of chorionic plate arteries in response to vasoconstrictors produced by preeclamptic placentas

Inadequate blood flow and increased vasoconstriction of the placenta contribute to pregnancy associated disorders such as preeclampsia (PE). Because placental vessels lack autonomic innervation, humoral effects of the placenta must play critical roles in regulation of fetal-placental vascular contractility. In this study, we examined the nature of humoral factors produced by PE trophoblasts on placental vessel contractility using an organ bath perfusion model. Vasomotor responses were studied in vitro using placental chorionic plate arteries. Vessel rings from third branch chorionic plate arteries were dissected from human placentas following normal or PE delivery. The arterial rings were equilibrated in Krebs Henseleit buffer and exposed to placental conditioned medium, which was prepared by culture of villous tissue from PE placentas. Receptor antagonists for angiotensin II (ANG II), thromboxane (TX), and endothelin (ET) were used to determine which humoral factor produced by placental tissue (trophoblasts) was more effective in promoting vasoconstriction. The role of angiotensin converting enzyme (ACE) and non-ACE ANG II generating enzymes in regulation of placental vasomotor tone were also investigated. A total of 80 arterial rings from 48 placentas were studied. Our results showed: 1) enhanced vasomotor tone in arteries from PE placentas compared to those from normal placentas; 2) PE-CM induced vaso-constrictive activity could be partially attenuated by receptor antagonists for TX, ANG II and ET, respectively; and 3) chymostatin (a chymase inhibitor) produced a stronger inhibitory effect than captopril (ACE inhibitor) on PE conditioned medium induced vasoconstriction. Our data demonstrate increased vasocontractility in PE placentas and suggest that the non-ACE pathway is probably a major source of ANG II produced in the human placenta.

Leukocyte-platelet interaction in pregnancies complicated with preeclampsia

OBJECTIVE

Pregnancy is characterized by haemostasis activation, and in preeclampsia endothelial dysfunction, platelet and leukocyte activation are further characteristic features. The aim of this study was to investigate to which extent platelets from normotensive pregnant women or those with preeclampsia are circulating as microparticles or platelet-platelet aggregates. We also investigated if platelet-leukocyte multiconjugates were differently present in nonpregnant and pregnant women.

STUDY DESIGN

Using flow cytometry we investigated these parameters in basal samples and after in vitro stimulation with adenosine diphosphate (ADP) or thrombin receptor activation peptide. This was done in samples from 20 matched preeclamptic and normotensive pregnant women and in a group of 12 nonpregnant women.

RESULTS

In the basal state we found that women with preeclampsia had a smaller portion of microparticles circulating than the normotensive pregnant women, Upon ADP stimulation both pregnancy groups showed a higher percentage of monocytes and granulocytes with platelets attached and also a higher number of platelets attached to each monocyte and granulocyte than in the group of nonpregnant individuals.

CONCLUSION

This article presents further evidence that changes from the nonpregnant to the pregnant state are associated with hemostasis activation as an integrated part of an inflammatory reaction that is even more pronounced when pregnancy is complicated with preeclampsia.

Microparticle subpopulations are increased in preeclampsia: possible involvement in vascular dysfunction?

OBJECTIVE

The purpose of this study was to investigate the cellular origin and numbers of circulating microparticles in normal pregnancy and preeclampsia.

STUDY DESIGN

Plasma samples from 10 women with preeclampsia, from 10 normal pregnant women, and from 10 nonpregnant women matched for age and gestation, were analyzed by flow cytometry.

RESULTS

The total number of circulating microparticles was unaltered in pregnancy and preeclampsia. The largest portion of microparticles was derived from platelets in all groups. T-suppressor cell microparticle numbers were decreased in normal pregnancy (P =.04). In preeclampsia T-suppressor, T-helper cell, and granulocyte microparticle numbers were increased (P =.008,.008, and.03, respectively). Elastase concentrations were increased in preeclampsia (P =.02) and correlated with granulocyte microparticle numbers (P =.006). Elastase concentrations correlated with systolic and diastolic blood pressure (P =.001 and.003, respectively), and granulocyte microparticle numbers correlated with systolic blood pressure (P =.05).

CONCLUSION

Numbers of T-cell and granulocyte microparticles are increased in preeclampsia. Whether these altered microparticle numbers cause vascular dysfunction in preeclampsia or are a consequence of the disease remains to be established.

Neutrophil activation induced by placental factors in normal and pre-eclamptic pregnancies in vitro

Increased neutrophil activation has been demonstrated in women with pre-eclampsia. Activated neutrophils may play a significant role in the vascular endothelial pathophysiology in this disorder of pregnancy. How neutrophils become activated in pre-eclampsia is unknown. It has been proposed that activating factors could be produced and released by the placenta. To test if placental factors could stimulate neutrophil activation and what mechanism might be involved, neutrophils isolated from healthy female volunteers were exposed to the conditioned medium (CM) derived from either normal (Nor) or pre-eclamptic (PE) placental villous culture. Neutrophil-endothelial adhesion, neutrophil superoxide generation, elastase activity and integrin expression were measured. The data were analysed by ANOVA. A P value less than 0.05 was considered statistically significant. All values are expressed as a mean+/-s.e. We found: (1) neutrophil-endothelial adhesion was significantly increased in neutrophils exposed PE-CM than those exposed to Nor-CM and non-CM, P< 0.01; (2) both Nor-CM and PE-CM could stimulate neutrophils to generate more superoxide radicals; (3) there was no difference in elastase activity after neutrophil exposure to Nor-CM compared to PE-CM, P> 0.1; (4) significant changes in CD62L and CD11b expression were found in neutrophils exposed to PE-CM. We conclude that factors produced by the placenta can activate neutrophils by an increase in superoxide generation and modulation of adhesion molecule expression. Upregulation of surface adhesion molecule CD11 expression may be responsible for the increased neutrophil-endothelial adhesion induced by factors derived from pre-eclamptic placentae.