The C5b-9 membrane attack complex of complement activation localizes to villous trophoblast injury in vivo and modulates human trophoblast function in vitro

Increased Complement Activation and Decreased ADAMTS13 Activity Are Associated with Genetic Susceptibility in Patients with Preeclampsia/HELLP Syndrome Compared to Healthy Pregnancies: An Observational Case-Controlled Study

Preeclampsia is a progressive multi-systemic disorder characterized by proteinuria, critical organ damage, and new-onset hypertension. It can be further complicated by HELLP syndrome (hemolysis, elevated liver enzymes, low platelets), resulting in critical liver or renal damage, disseminated coagulation, and grand mal seizures. This study aimed to examine the involvement of ADAMTS13, von Willebrand, and the complement system in the pathogenesis of preeclampsia/HELLP syndrome. We studied 30 Caucasian preeclamptic pregnant women and a control group of 15 healthy pregnancies. Genetic sequencing of ADAMTS13 and complement regulatory genes (MiniSeq System, Illumina) was performed. The modified Ham test was used to check for complement activation, ADAMTS13 activity, von Willebrand antigen (vWFAg) levels, and soluble C5b-9 levels were measured. Patients with preeclampsia had a decreased ADAMTS13 activity and increased C5b-9 levels. The vWFAg was significantly correlated with ADAMTS13 activity (r = 0.497, p = 0.003). Risk-factor variants were found in the genes of ADAMTS13, C3, thrombomodulin, CFB, CFH, MBL2, and, finally, MASP2. A portion of pregnant women with preeclampsia showed a decline in ADAMTS13 activity, correlated with vWFAg levels. These patients also exhibited an elevated complement activation and high-risk genetic variants in regulatory genes. Further research is needed to determine if these factors can serve as reliable biomarkers.

Comprehensive Review of Hypertensive Disorders Related to Pregnancy

Hypertensive disorder of pregnancy is a common complication during pregnancy that affects approximately 10% of pregnancies and is responsible for nearly 14% of maternal deaths worldwide. It affects the mother and the fetus simultaneously, sometimes putting the health of the mother and the fetus at odds with each other. It may present with only hypertension and proteinuria or with life-threatening complications in the mother such as eclampsia; stroke; acute pulmonary edema; acute renal failure; disseminated intravascular coagulation; placental abruption; hemolysis, elevated liver enzymes, and low platelet syndrome; pregnancy loss; and fetal growth restriction and prematurity resulting from the frequent need of delivering preterm in the fetus. In this review, we aimed to describe hypertensive disorders of pregnancy, mainly preeclampsia and chronic hypertension in pregnancy, by discussing the pathophysiology, the central role of abnormal placentation, the release of antiangiogenic factors in the circulation and immunological factors, the clinical outcome in the mother and the fetus, and the diagnostic criteria and principles of management of both the conditions. We also discuss possible screening methods and prevention of preeclampsia using low-dose aspirin and eclampsia prophylaxis.

The role of immune cells and mediators in preeclampsia

Preeclampsia is a hypertensive disorder of major concern in pregnancy than can lead to intrauterine growth restriction, placental abruption and stillbirth. The pathophysiology of preeclampsia is multifactorial, including not only kidney dysfunction but also endothelial dysfunction, as the maternal endothelium becomes exposed to placental factors that are released into the circulation and increase systemic levels of vasoconstrictors, oxidative stress, anti-angiogenic factors and inflammatory mediators. Importantly, inflammation can lead to insufficient placental perfusion and low birthweight in offspring. Various innate and adaptive immune cells and mediators have been implicated in the development of preeclampsia, in which oxidative stress is associated with activation of the maternal inflammatory response. Immune cells such as regulatory T cells, macrophages, natural killer cells, and neutrophils are known to have major causative roles in the pathology of preeclampsia, but the contributions of additional immune cells such as B cells, inflammatory cytokines and anti-angiotensin II type 1 receptor autoantibodies are also now recognized. Immunological interventions, therefore, have therapeutic potential in this disease. Here, we provide an overview of the immune responses that are involved in the pathogenesis of preeclampsia, including the role of innate and adaptive immune cells and mediators.

Soluble concentrations of the terminal complement complex C5b-9 correlate with end-organ injury in preeclampsia

OBJECTIVE

We sought to determine if soluble levels of C5b-9, the terminal complement complex, correlate with end-organ injury in preeclampsia.

STUDY DESIGN

Project COPA (Complement and Preeclampsia in the Americas), a multi-center observational study in Colombia from 2015 to 2016, enrolled hypertensive pregnant women into four groups: chronic hypertension, gestational hypertension, preeclampsia, and preeclampsia with severe features. Trained coordinators collected clinical data, blood and urine. End-organ injury was defined by serum creatinine ≥ 1.0 mg/dl, aspartate transaminase ≥ 70U/L, platelet count < 150,000/µl, or lactate dehydrogenase ≥ 500 U/L. Data were analyzed by χ² or Fisher's exact test with significance at P < 0.05.

MAIN OUTCOME MEASURE

C5b-9 concentrations in plasma and urine, using enzyme linked immunosorbent assays.

RESULTS

In total, 298 hypertensive participants were enrolled. Plasma and urine C5b-9 levels were measured in all participants and stratified by quartile (Q1-4), from lowest to highest C5b-9 concentration. Participants with low plasma C5b-9 levels (Q1) were more likely to have end-organ injury compared to those with higher levels (Q2-Q4) [platelet count < 150,000/μl (20.8% vs. 8.4%, P = 0.01); elevated serum creatinine ≥ 1.0 mg/dl (14.9% vs. 4.5%, P = 0.009)]. In contrast, participants with high urinary C5b-9 levels (Q4) were more likely to have end-organ injury compared to those with lower levels (Q1-Q3) [platelet count < 150,000/μl (19.7% vs. 7.4%, P = 0.003); elevated serum creatinine ≥ 1.0 mg/dl (12.3% vs. 4.4%, P = 0.025)].

CONCLUSION

We identified a pattern of increased urine and low plasma C5b-9 levels in patients with preeclampsia and end-organ injury. Soluble C5b-9 levels may be used to identify complement-mediated end-organ injury in preeclampsia.

Molecular Advances in Preeclampsia and HELLP Syndrome

Preeclampsia (PE) constitutes one of the principal reasons for maternal and perinatal morbidity and mortality worldwide. The circumstance typically implicates formerly healthful normotensive women, after 20 weeks of gestation, typically withinside the third trimester, without regarded threat elements or past deliveries. PE can be further complicated with hemolysis and thrombocytopenia, leading to the emergence of HELLP syndrome (Hemolysis, Elevated Liver enzymes, Low platelets). Both conditions are classified as hypertensive diseases of pregnancy (HDP), and their pathogenesis has been linked to an excessive maternal inflammatory response, accompanied by enhanced endothelial activation. Several studies have found that in pregnancies affected by PE/HELLP, von Willebrand factor (vWF) antigen levels (vWF:Ag) are significantly elevated, while its cleaving protease (ADAMTS-13, A Disintegrin-like and Metalloprotease with Thrombospondin type 1 motif, member 13) activity is normal to decreased. Furthermore, the higher urine excretion of the terminal complement complex C5b-9, as well as its greater deposition in the placental surface in preeclamptic women, imply that the utero-placental unit’s distinctive deficits are intimately tied to disproportionate complement activation. The goal of this updated evaluation is to provide the most up-to-date molecular advances in the pathophysiology of PE/HELLP syndromes. Recent medical data on vWF:Ag levels in patients with PE, ADAMTS-13, and dysregulation of the complement system, are highlighted and evaluated. Furthermore, we discuss the relationship between those entities and the progression of the disease, as well as their significance in the diagnostic process. Finally, considering the difficulties in analyzing and controlling those symptoms in pregnant women, we can provide a current diagnostic and therapeutic algorithm.

Syncytiotrophoblast stress in preeclampsia: the convergence point for multiple pathways

Preeclampsia evolves in 2 stages: a placental problem that generates signals to the mother to cause a range of responses that comprise the second stage (preeclampsia syndrome). The first stage of early-onset preeclampsia is poor placentation, which we here call malplacentation. The spiral arteries are incompletely remodeled, leading to later placental malperfusion, relatively early in the second half of pregnancy. The long duration of the first stage (several months) is unsurprisingly associated with fetal growth restriction. The first stage of late-onset preeclampsia, approximately 80% of total cases, is shorter (several weeks) and part of a process that is common to all pregnancies. Placental function declines as it outgrows uterine capacity, with increasing chorionic villous packing, compression of the intervillous space, and fetal hypoxia, and causes late-onset clinical presentations such as "unexplained" stillbirths, late-onset fetal growth restriction, or preeclampsia. The second stages of early- and late-onset preeclampsia share syncytiotrophoblast stress as the most relevant feature that causes the maternal syndrome. Syncytiotrophoblast stress signals in the maternal circulation are probably the most specific biomarkers for preeclampsia. In addition, soluble fms-like tyrosine kinase-1 (mainly produced by syncytiotrophoblast) is the best-known biomarker and is routinely used in clinical practice in many locations. How the stress signals change over time in normal pregnancies indicates that syncytiotrophoblast stress begins on average at 30 to 32 weeks' gestation and progresses to term. At term, syncytiotrophoblast shows increasing markers of stress, including apoptosis, pyroptosis, autophagy, syncytial knots, and necrosis. We label this phenotype the "twilight placenta" and argue that it accounts for the clinical problems of postmature pregnancies. Senescence as a stress response differs in multinuclear syncytiotrophoblast from that of mononuclear cells. Syncytiotrophoblast irreversibly acquires part of the senescence phenotype (cell cycle arrest) when it is formed by cell fusion. The 2 pathways converge on the common pathologic endpoint, syncytiotrophoblast stress, and contribute to preeclampsia subtypes. We highlight that the well-known heterogeneity of the preeclampsia syndrome arises from different pathways to this common endpoint, influenced by maternal genetics, epigenetics, lifestyle, and environmental factors with different fetal and maternal responses to the ensuing insults. This complexity mandates a reassessment of our approach to predicting and preventing preeclampsia, and we summarize research priorities to maximize what we can learn about these important issues.

Complement activation and regulation in preeclampsia and hemolysis, elevated liver enzymes, and low platelet count syndrome

The complement system is critical to human health owing to its central role in host defense and innate immunity. During pregnancy, the complement system must be appropriately regulated to allow for immunologic tolerance to the developing fetus and placenta. Although some degree of complement activation can be seen in normal pregnancy, the fetus seems to be protected in part through the placental expression of complement regulatory proteins, which inhibit complement activation at different steps along the complement activation cascade. In women who develop preeclampsia and hemolysis, elevated liver enzymes, and low platelet count syndrome, there is a shift toward increased complement activation and decreased complement regulation. There is an increase in placental deposition of C5b-9, which is the terminal effector of classical, lectin, and alternative complement pathways. C5b-9 deposition stimulates trophoblasts to secrete soluble fms-like tyrosine kinase-1, which sequesters vascular endothelial growth factor and placental growth factor. Pathogenic mutations or deletions in complement regulatory genes, which predispose to increased complement activation, have been detected in women with preeclampsia and hemolysis, elevated liver enzymes, and low platelet count syndrome. Before the disease, biomarkers of alternative complement pathway activation are increased; during active disease, biomarkers of terminal complement pathway activation are increased. Urinary excretion of C5b-9 is associated with preeclampsia with severe features and distinguishes it from other hypertensive disorders of pregnancy. Taken together, existing data link preeclampsia and hemolysis, elevated liver enzymes, and low platelet count syndrome with increased activation of the terminal complement pathway that, in some cases, may be influenced by genetic alterations in complement regulators. These findings suggest that the inhibition of the terminal complement pathway, possibly through C5 blockade, may be an effective strategy to treat preeclampsia and hemolysis, elevated liver enzymes, and low platelet count syndrome, but this strategy warrants further evaluation in clinical trials.

Pathogenesis, Diagnosis and Management of Obstetric Antiphospholipid Syndrome: A Comprehensive Review

Antiphospholipid syndrome is an autoimmune disorder characterized by vascular thrombosis and/or pregnancy morbidity associated with persistent antiphospholipid antibody positivity. Cases fulfilling the Sydney criteria for obstetric morbidity with no previous thrombosis are known as obstetric antiphospholipid syndrome (OAPS). OAPS is the most identified cause of recurrent pregnancy loss and late-pregnancy morbidity related to placental injury. Cases with incomplete clinical or laboratory data are classified as obstetric morbidity APS (OMAPS) and non-criteria OAPS (NC-OAPS), respectively. Inflammatory and thrombotic mechanisms are involved in the pathophysiology of OAPS. Trophoblasts, endothelium, platelets and innate immune cells are key cellular players. Complement activation plays a crucial pathogenic role. Secondary placental thrombosis appears by clot formation in response to tissue factor activation. New risk assessment tools could improve the prediction of obstetric complication recurrences or thromboses. The standard-of-care treatment consists of low-dose aspirin and prophylactic low molecular weight heparin. In refractory cases, the addition of hydroxychloroquine, low-dose prednisone or IVIG improve pregnancy outcomes. Statins and eculizumab are currently being tested for treating selected OAPS women. Finally, we revisited recent insights and concerns about the pathophysiology, diagnosis and management of OAPS.

Quantitative Alterations in Complement Alternative Pathway and Related Genetic Analysis in Severe Phenotype Preeclampsia

Background

Preeclampsia and hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome share many clinical and biologic features with thrombotic microangiopathy syndromes caused by complement abnormalities. Our hypothesis was that similar functional and genetic alterations in the complement alternative pathway (CAP) are present in these disorders of pregnancy.

Methods

We conducted quantitative analysis of proteins involved in CAP using ELISA and nephelometry on prospectively collected blood samples from patients with severe phenotype preeclampsia (defined as delivery ≤34 weeks due to preeclampsia), HELLP syndrome, or eclampsia, and matched normotensive controls (n=25 in each arm) between 2011 and 2016. Sequencing was performed to interrogate 14 genes encoding CAP components.

Results

Both groups were similar in age, gravidity, parity, marital status, and race. The study group had a higher BMI (mean±SD, 32±8 versus 25±4 kg/m²; P=0.002) and earlier gestational age at delivery (32.5±3.6 versus 40.3±1 weeks; P<0.001). Serologic studies demonstrated elevated Bb subunit (median [range], 1.2 [0.5-4.3] versus 0.6 [0.5-1] μg/ml; P<0.001), complement C5 concentration (28 [18-33] versus 24 [15-34] mg/dl; P=0.03), and sMAC (371 [167-761] versus 184 [112-249] ng/ml; P<0.001) concentrations in patients with preeclampsia. Two thirds of patients with preeclampsia had at least one nonsynonymous sequence variant in CAP genes.

Conclusion

Patients with severe phenotype preeclampsia manifest functional alterations in CAP activation. Genetic variants in the CAP genes were detected in several patients, but a larger population study is necessary to fully evaluate genetic risk. Genetic screening and complement-targeted treatment may be useful in risk stratification and novel therapeutic approaches.

Dysregulation of complement system during pregnancy in patients with preeclampsia: A prospective study

Recent studies have shown that aberrant activation of the complement system plays an important role in the pathogenesis of preeclampsia. There is evidence to suggest that aberrant activation of the complement system may already be present during the first trimester. Here, we performed a prospective study in which peripheral blood samples were collected from 500 women during pregnancy. Twenty-one patients (41 specimens) suffering from preeclampsia later in pregnancy were classified into the study group, and sixty-three gravidas with normal pregnancies (136 specimens) were selected as the control group. The plasma concentrations of complement factor B (CFB), C1q, complement factor H (CFH), C3c, C4, C3a, C5a and soluble C5b-9 (sC5b-9) were measured. The levels of CFB (P = 0.004), CFH (P = 0.002), C1q (P = 0.044), C3c (P = 0.032) and C4 (P = 0.015) were significantly higher in preeclampsia than in normal pregnancy during the first trimester, and these levels became similar to those in normal pregnancy thereafter. Before the onset of preeclampsia, the levels of C3a, C5a and sC5b-9 in the preeclampsia group were similar to those in control group even in late pregnancy. C3a levels showed a significant positive correlation with C5a in normal pregnancy (r=0.658, P<0.01) but not in preeclampsia (r = 0.001, P = 1).Thus, we found that aberrant activation of the complement system in patients with preeclampsia was initiated during the first trimester but returned to normal pregnancy levels in the second trimester. At the same time, there is aberrant regulation of complement activation at the C3a-C5a level in preeclampsia during pregnancy.

Mechanism of Placenta Damage in Gestational Diabetes Mellitus by Investigating TXNIP of Patient Samples and Gene Functional Research in Cell Line

INTRODUCTION

Gestational diabetes mellitus (GDM) is a gestational complication that affects maternal and child health. The placenta provides the fetus with the necessary nutrition and oxygen and takes away the metabolic waste. Patients with GDM are diagnosed and treated merely on the basis of the blood glucose level; this approach does nothing to help evaluate the status of the placenta, which is worth noting in GDM. The purpose of this research was to clarify the relation between thioredoxin-interacting protein (TXNIP) and reactive oxygen species (ROS) in the placenta of patients with GDM, which has thus far remained unclear.

METHODS

The expression of TXNIP in the placentas of 10 patients with GDM and 10 healthy puerperae (control group) was investigated via immunofluorescence. The relation among TXNIP, ROS, and the function of mitochondria was explored in HTR-8/SVneo cells stimulated by high glucose (HG).

RESULTS

The results showed the expression of TXNIP in the placentas of patients with GDM was higher than that in the control group, and the expression of TXNIP in HTR-8/SVneo cells treated with HG was higher than that in the control group, causing the accumulation of ROS and changes of mitochondria, promoting apoptosis and inhibition of migration.

CONCLUSIONS

High expression of TXNIP caused by HG mediates the increasing ROS and the mitochondria dysfunction in GDM; this impairs the function of the placenta and is the basis for the prediction of perinatal outcome.

Regulation of the complement system and immunological tolerance in pregnancy

Preeclampsia is a serious vascular complication of the human pregnancy, whose etiology is still poorly understood. In preeclampsia, exacerbated apoptosis and fragmentation of the placental tissue occurs due to developmental qualities of the placental trophoblast cells and/or mechanical and oxidative distress to the syncytiotrophoblast, which lines the placental villi. Dysregulation of the complement system is recognized as one of the mechanisms of the disease pathology. Complement has the ability to promote inflammation and facilitate phagocytosis of placenta-derived particles and apoptotic cells by macrophages. In preeclampsia, an overload of placental cell damage or dysregulated complement system may lead to insufficient clearance of apoptotic particles and placenta-derived debris. Excess placental damage may lead to sequestration of microparticles, such as placental vesicles, to capillaries in the glomeruli of the kidney and other vulnerable tissues. This phenomenon could contribute to the manifestations of typical diagnostic symptoms of preeclampsia: proteinuria and new-onset hypertension. In this review we propose that the complement system may serve as a regulator of the complex tolerance and clearance processes that are fundamental in healthy pregnancy. It is therefore recommended that further research be conducted to elucidate the interactions between components of the complement system and immune responses in the context of complicated and healthy pregnancy.

Absence of Distinct Immunohistochemical Distribution of Annexin A5, C3b, C4d, and C5b-9 in Placentas From Patients With Antiphospholipid Antibodies, Preeclampsia, and Systemic Lupus Erythematosus

INTRODUCTION

In pregnancy, the presence of preeclampsia (PEC), systemic lupus erythematosus (SLE), and/or antiphospholipid antibody syndrome (APLS) is characterized by poor obstetric outcomes, with potential adverse effects for both mother and fetus. Although the histopathologic changes observed in these entities have been well established, the pathogenic mediators associated with tissue injury are poorly understood.

METHODS

Forty placentas were evaluated, including 10 patients with preeclampsia, 9 with SLE, 11 with APLS, and 10 disease-free controls. Each case was subjected to a panel of immunohistochemical markers including C3b, C4d, Annexin A5, and C5b-9. Staining was graded on intensity and distribution.

RESULTS

C4d staining was distinctly different among disease groups and controls. Moreover, 6/10 PEC cases, 3/9 SLE cases, and 4/11 APLS cases showed at least focal staining for C4d. All controls were negative. Annexin A5 (AnxA5) staining showed intrinsic variability in all disease groups, while 10/10 controls showed diffuse, strong staining (2+ or 3+). C3b staining was heterogeneous among groups.

DISCUSSION

Previously, antiphospholipid antibody (aPLA)-associated pregnancy complications have been thought to be a consequence of a unique aPLA-mediated pathogenic mechanism. However, the immunohistochemical similarity (increased complement and decreased AnxA5 staining) observed in placentas from patients with APLS, PEC, and SLE suggests that aPLA-associated pregnancy complications may reflect a more general autoimmune mechanism.

Effects of glycol-split low molecular weight heparin on placental, endothelial, and anti-inflammatory pathways relevant to preeclampsia

Low molecular weight heparin (LMWH) is being investigated as a potential preventative therapy against preeclampsia. There is evidence suggesting that LMWH may prevent preeclampsia through anticoagulation-independent mechanisms. In this study, we compared the in vitro placental, endothelial, and anti-inflammatory effects of an LMWH (dalteparin) with a nonanticoagulant, glycol-split heparin derivative (gsHep). In contrast with dalteparin, gsHep did not interact with antithrombin III, possess significant anti-Factor Xa activity, or significantly prolong in vitro plasma clotting time. However, dalteparin and gsHep were otherwise mechanistically similar, both interacting with soluble fms-like tyrosine kinase-1 (sFlt1) and promoting release of the pro-angiogenic protein placental growth factor, but not the antiangiogenic sFlt1, from healthy placental villous explants. Placental explant media pretreated with dalteparin or gsHep significantly stimulated endothelial cell tube formation compared to untreated explants. Lastly, dalteparin and gsHep both significantly suppressed inflammation by inhibiting complement activation and leukocyte adhesion to endothelial cells that were activated using serum from preeclamptic women. Our data suggest that nonanticoagulant heparin derivatives may be utilized as a tool to distinguish the anticoagulation-independent mechanisms of LMWH, and provide insight into the role of anticoagulation in the prevention of preeclampsia.

Assessment of blood-brain barrier integrity and neuroinflammation in preeclampsia

BACKGROUND

Although blood-brain barrier integrity is intact under normal pregnancy conditions, animal studies suggest that blood-brain barrier impairment occurs in preeclampsia. Yet, human data are limited, and the integrity of the blood-brain barrier has not been assessed in women with preeclampsia.

OBJECTIVE

We sought to test the hypothesis that the integrity of the blood-brain barrier is impaired and that neuroinflammation is increased in women with preeclampsia.

STUDY DESIGN

We performed an observational case-control study in pregnant women >24 weeks gestation who underwent spinal anesthesia for elective cesarean delivery or combined spinal epidural analgesia for labor. Cases were women with preeclampsia, and control subjects were women with either healthy pregnancy, chronic hypertension, or gestational hypertension. Paired samples of blood, urine, and cerebrospinal fluid were collected from each subject before delivery. We measured albumin, C5a, C5b-9, tumor necrosis factor-α, and interleukin-6 concentrations in plasma and cerebrospinal fluid, and albumin, C5a, and C5b-9 concentrations in urine, using colorimetric or enzyme-linked immunosorbent assays. The ratio of albumin in cerebrospinal fluid to plasma (Qalb) was used as a surrogate for maternal blood-brain barrier integrity. Cerebrospinal fluid concentrations of C5a, C5b-9, tumor necrosis factor-α, and interleukin-6 were used as surrogate markers of neuroinflammation. Differences in Qalb and cerebrospinal fluid protein concentrations between groups were assessed by nonparametric test of medians.

RESULTS

Forty-eight subjects were enrolled, which included 16 cases with preeclampsia, 16 control subjects with healthy pregnancy, and 16 control subjects with either chronic or gestational hypertension. Qalb values were not increased in preeclampsia cases compared with healthy or hypertensive control subjects (Qalb median, 3.5 [interquartile range, 2.9-5.1] vs 3.9 [interquartile range, 3.0-4.8] vs 3.9 [interquartile range, 3.0-4.8]; P=.78]. Moreover, Qalb values were not increased in the subset of women with preeclampsia with severe features (n=8) compared with those without severe features (n=8; Qalb median, 3.5 [interquartile range, 3.3-4.9] vs 3.7 [interquartile range, 2.3-5.5]; P=.62]. Cerebrospinal fluid concentrations of C5a, C5b-9, tumor necrosis factor-α and interleukin-6 were not increased in cases of preeclampsia, compared with control subjects with either healthy pregnancy, chronic hypertension, or gestational hypertension (P>.05, all comparisons). In contrast to the negative findings in cerebrospinal fluid, plasma concentrations of both C5b-9 and interleukin-6 and urine concentrations of C5a and C5b-9 were increased in cases of preeclampsia.

CONCLUSION

Through measurements of albumin, complement proteins, and cytokines in paired samples of blood and cerebrospinal fluid at the time of delivery, we found no evidence of blood-brain barrier impairment or neuroinflammation in preeclampsia. Larger studies that will investigate a wider range of proteins are suggested to validate our findings.

Low-dose aspirin protective effects are correlated with deregulation of HNF factor expression in the preeclamptic placentas from mice and humans

Aspirin (acetyl-salicylic acid) is one of the most ancient drugs of the human pharmacopeia. Nonetheless, its action at low doses is not well understood at the molecular level. One of the applications of low-dose aspirin treatment is the prevention of preeclampsia (PE) in patients at risk. Foeto-placental overexpression of the STOX1A transcription factor in mice triggers PE symptoms. Transcriptomic analysis of the placentas, showed that aspirin massively down-regulates genes of the coagulation and complement cascade, as well as genes involved in lipid transport. The genes modified by aspirin treatment are not the ones that are modified by STOX1 overexpression, suggesting that aspirin could act downstream, symptomatically on the preeclamptic disease. Bioinformatics analysis of the promoters of the deregulated genes showed that they are strongly enriched in HNF transcription factors-binding sites, in accordance with existing literature showing their roles as regulators of coagulation. Two of these transcription factors, Hnf1β and Hnf4α are found down-regulated by aspirin treatment. In parallel, we show that in human patient placentas, aspirin-induced deregulations of genes of the coagulation cascade are also observed. Finally, the expression of Hnf1β target sequences (Kif12, F2, Hnf4α promoters and a synthetic concatemer of the Hnf1β-binding site) were investigated by transfection in trophoblast cell models, with or without aspirin treatment and with or without STOX1A overexpression. In this model we observed that STOX1A and aspirin tended to synergize in the down-regulation of Hnf1β target genes in trophoblasts.

Integrated Systems Biology Approach Identifies Novel Maternal and Placental Pathways of Preeclampsia

Preeclampsia is a disease of the mother, fetus, and placenta, and the gaps in our understanding of the complex interactions among their respective disease pathways preclude successful treatment and prevention. The placenta has a key role in the pathogenesis of the terminal pathway characterized by exaggerated maternal systemic inflammation, generalized endothelial damage, hypertension, and proteinuria. This sine qua non of preeclampsia may be triggered by distinct underlying mechanisms that occur at early stages of pregnancy and induce different phenotypes. To gain insights into these molecular pathways, we employed a systems biology approach and integrated different "omics," clinical, placental, and functional data from patients with distinct phenotypes of preeclampsia. First trimester maternal blood proteomics uncovered an altered abundance of proteins of the renin-angiotensin and immune systems, complement, and coagulation cascades in patients with term or preterm preeclampsia. Moreover, first trimester maternal blood from preterm preeclamptic patients in vitro dysregulated trophoblastic gene expression. Placental transcriptomics of women with preterm preeclampsia identified distinct gene modules associated with maternal or fetal disease. Placental "virtual" liquid biopsy showed that the dysregulation of these disease gene modules originates during the first trimester. In vitro experiments on hub transcription factors of these gene modules demonstrated that DNA hypermethylation in the regulatory region of ZNF554 leads to gene down-regulation and impaired trophoblast invasion, while BCL6 and ARNT2 up-regulation sensitizes the trophoblast to ischemia, hallmarks of preterm preeclampsia. In summary, our data suggest that there are distinct maternal and placental disease pathways, and their interaction influences the clinical presentation of preeclampsia. The activation of maternal disease pathways can be detected in all phenotypes of preeclampsia earlier and upstream of placental dysfunction, not only downstream as described before, and distinct placental disease pathways are superimposed on these maternal pathways. This is a paradigm shift, which, in agreement with epidemiological studies, warrants for the central pathologic role of preexisting maternal diseases or perturbed maternal-fetal-placental immune interactions in preeclampsia. The description of these novel pathways in the "molecular phase" of preeclampsia and the identification of their hub molecules may enable timely molecular characterization of patients with distinct preeclampsia phenotypes.

Molecular actions of heparin and their implications in preventing pre-eclampsia

Pre-eclampsia, a hypertensive disorder of pregnancy, continues to be a significant cause of global maternal morbidity. Low-dose aspirin remains the only standard-of-care prophylactic therapy for preventing pre-eclampsia, but is limited in efficacy. Heparin and its derivatives may further enhance the efficacy of aspirin therapy to prevent pre-eclampsia, but the mechanisms mediating this augmentative effect are not known. Although heparin is an anticoagulant agent, it also possesses many anticoagulant-independent properties that may be relevant in the prevention of pre-eclampsia, including effects on placental, vascular and inflammatory function. This review summarizes the non-anticoagulant properties of heparin, and extrapolates how these actions may influence the trajectory of pre-eclampsia pathogenesis as a means of pathway-specific therapy.

Angiogenic factor imbalance precedes complement deposition in placentae of the BPH/5 model of preeclampsia

Preeclampsia (PE), a hypertensive disorder of pregnancy, is a leading cause of maternal and fetal morbidity and mortality. Although the etiology is unknown, PE is thought to be caused by defective implantation and decidualization in pregnancy. Pregnant blood pressure high (BPH)/5 mice spontaneously develop placentopathies and maternal features of human PE. We hypothesized that BPH/5 implantation sites have transcriptomic alterations. Next-generation RNA sequencing of implantation sites at peak decidualization, embryonic day (E)7.5, revealed complement gene up-regulation in BPH/5 vs. controls. In BPH/5, expression of complement factor 3 was increased around the decidual vasculature of E7.5 implantation sites and in the trophoblast giant cell layer of E10.5 placentae. Altered expression of VEGF pathway genes in E5.5 BPH/5 implantation sites preceded complement dysregulation, which correlated with abnormal vasculature and increased placental growth factor mRNA and VEGF₁₆₄ expression at E7.5. By E10.5, proangiogenic genes were down-regulated, whereas antiangiogenic sFlt-1 was up-regulated in BPH/5 placentae. We found that early local misexpression of VEGF genes and abnormal decidual vasculature preceded sFlt-1 overexpression and increased complement deposition in BPH/5 placentae. Our findings suggest that abnormal decidual angiogenesis precedes complement activation, which in turn contributes to the aberrant trophoblast invasion and poor placentation that underlie PE.-Sones, J. L., Merriam, A. A., Seffens, A., Brown-Grant, D.-A., Butler, S. D., Zhao, A. M., Xu, X., Shawber, C. J., Grenier, J. K., Douglas, N. C. Angiogenic factor imbalance precedes complement deposition in placentae of the BPH/5 model of preeclampsia.

The Role of Complement Inhibition in Thrombotic Angiopathies and Antiphospholipid Syndrome

Antiphospholipid syndrome (APS) is characterized by thrombosis (arterial, venous, small vessel) and/or pregnancy morbidity occurring in patients with persistently positive antiphospholipid antibodies (aPL). Catastrophic APS is the most severe form of the disease, characterized by multiple organ thromboses occurring in a short period and commonly associated with thrombotic microangiopathy (TMA). Similar to patients with complement regulatory gene mutations developing TMA, increased complement activation on endothelial cells plays a role in hypercoagulability in aPL-positive patients. In mouse models of APS, activation of the complement is required and interaction of complement (C) 5a with its receptor C5aR leads to aPL-induced inflammation, placental insufficiency, and thrombosis. Anti-C5 antibody and C5aR antagonist peptides prevent aPL-mediated pregnancy loss and thrombosis in these experimental models. Clinical studies of anti-C5 monoclonal antibody in aPL-positive patients are limited to a small number of case reports. Ongoing and future clinical studies of complement inhibitors will help determine the role of complement inhibition in the management of aPL-positive patients.

Atypical haemolytic uraemic syndrome and pregnancy: outcome with ongoing eculizumab

BACKGROUND

A therapeutic strategy based on complement blockade by eculizumab is widely used to treat atypical haemolytic uraemic syndrome (aHUS). Recent data are available on the administration of eculizumab during pregnancy in patients treated for paroxysmal nocturnal haemoglobinuria but there are very few data for aHUS patients.

METHODS

We analysed the use of eculizumab for the treatment of aHUS during five pregnancies in three patients and studied an additional pregnancy without eculizumab. Obstetrical data and maternal and foetal complications during pregnancy, at delivery, and during the post-partum period were recorded.

RESULTS

The mean age at pregnancy was 28.5 (range 25-33) years. The mean serum creatinine before pregnancy was 189 (range 130-300) µmol/L and the mean eGFR was 32 (range 18-45) mL/min/1.73 m². One patient who stopped eculizumab 3 weeks after conception had a termination due to a relapse of HUS at 12 weeks of gestation (WG) during a first pregnancy and an intrauterine death at 24 WG despite continuous eculizumab treatment during a second pregnancy. In the other four pregnancies, treatment stabilized clinical and laboratory markers until 29-34 WG, but did not prevent hemolysis, elevated liver enzymes and low platelet count (HELLP) syndrome in one patient or pre-eclampsia in two other patients. All babies were born preterm and two presented with growth retardation. The mean body weight was 1632.5 (range 1070-2500) g. The dose of eculizumab had to be increased during all pregnancies due to incomplete complement blockade.

CONCLUSIONS

Eculizumab therapy during pregnancy displayed no overt safety issues but did not appear to prevent HELLP syndrome or pre-eclampsia in these high-risk chronic kidney disease patients.

Polymorphisms in complement genes and risk of preeclampsia in Taiyuan, China

BACKGROUND AND OBJECTIVES

Altered immune response may be a part of the pathogenesis of preeclampsia. The few epidemiologic studies that have investigated the associations between genetic variations in the complement system genes and preeclampsia risk have reached inconsistent results. The aim of this study is to determine if polymorphisms in the complement system genes could influence the risk of preeclampsia.

METHODS

We examined 51 SNPs in the C3, C5, C6, MASP1, MBL2 and CD55 genes and the risk of preeclampsia and its clinical subtypes in a nested case-control study of 203 preeclampsia cases and 233 controls.

RESULTS

Both C6 and MASP1 were associated with the risk of preeclampsia. C6 (rs7444800, rs4957381) and MASP1 (rs1108450, rs3774282, rs698106) polymorphisms were associated with the risk of early-onset preeclampsia and severe preeclampsia, while MASP1 (rs1357134, rs698090) polymorphisms were associated with the risk of late-onset preeclampsia and severe preeclampsia.

CONCLUSIONS

Our study provided novel evidence that genetic variations in complement genes C6 and MASP1were associated with preeclampsia risk, and that the risk varied by preeclampsia subtypes.

Evaluation of proteomic biomarkers associated with circulating microparticles as an effective means to stratify the risk of spontaneous preterm birth

BACKGROUND

The analysis of circulating microparticles in pregnancy is of revolutionary potential because it represents an in vivo biopsy of active gestational tissues.

OBJECTIVE

We hypothesized that circulating microparticle signaling will differ in pregnancies that experience spontaneous preterm birth from those delivering at term and that these differences will be evident many weeks in advance of clinical presentation.

STUDY DESIGN

Utilizing plasma specimens obtained between 10 and 12 weeks' gestation as part of a prospectively collected birth cohort in which pregnancy outcomes are independently validated by 2 board-certified maternal-fetal medicine physicians, 25 singleton cases of spontaneous preterm birth ≤ 34 weeks were matched by maternal age, race, and gestational age of sampling (±2 weeks) with 50 uncomplicated term deliveries. Circulating microparticles from these first-trimester specimens were isolated and analyzed by multiple reaction monitoring mass spectrometry for potential protein biomarkers following previous studies. Markers with robust univariate performance in correlating spontaneous preterm birth were further evaluated for their biological relevance via a combined functional profiling/pathway analysis and for multivariate performance.

RESULTS

Among the 132 proteins evaluated, 62 demonstrated robust power of detecting spontaneous preterm birth in a bootstrap receiver-operating characteristic curve analysis at a false discovery rate of < 20% estimated via label permutation. Differential dependency network analysis identified spontaneous preterm birth-associated coexpression patterns linked to biological processes of inflammation, wound healing, and the coagulation cascade. Linear modeling of spontaneous preterm birth using a multiplex of the candidate biomarkers with a fixed sensitivity of 80% exhibited a specificity of 83% with median area under the curve of 0.89. These results indicate a strong potential of multivariate model development for informative risk stratification.

CONCLUSION

This project has identified functional proteomic factors with associated biological processes that are already unique in their expression profiles at 10-12 weeks among women who go on to deliver spontaneously ≤ 34 weeks. These changes, with further validation, will allow the stratification of patients at risk of spontaneous preterm birth before clinical presentation.

The Relationship of Longitudinal Levels of Complement Bb During Pregnancy with Preeclampsia

PROBLEM

To determine the understudied relationship between complement Bb during pregnancy in subjects with preeclampsia compared with normotensive controls.

METHOD OF STUDY

Nested case-control study.

RESULTS

Average Bb levels significantly decreased over time in pregnancy [weekly slope (S.E.): -0.0094 (0.0005), P < 0.01]. Cross-sectionally, at less than 10 weeks, Bb levels decreased with increasing gestational age in women who remained normotensive [weekly slope (S.E.): -0.007 (0.02) and for women who developed preeclampsia (weekly slope (S.E.): -0.059 (0.03) P = 0.12]. Among women who developed preeclampsia, Bb levels were greatest when samples were drawn in the gestational window of 15-20 weeks [(weekly slope (S.E.): 0.06 (0.02)], while levels among normotensive women were inversely related with gestational age [weekly slope (S.E.): -0.02 (0.01)]. The differences in slopes between cases and controls between 10 and 21 weeks' gestation were statistically significant (P = 0.003).

CONCLUSIONS

We suggest dysregulation of Bb activation between 10 and 20 weeks' gestation in women who develop preeclampsia.

Increased expression of perforin, granzyme B, and C5b-9 in villitis of unknown etiology

INTRODUCTION

Villitis of unknown etiology (VUE) is associated with fetal growth restriction. However, the underlying mechanisms of villous injury in placentas with VUE are still largely unknown. We aimed to verify whether apoptosis-related factors are increased in VUE placentas. Furthermore, we determined apoptosis of villous cells.

METHODS

Six placentas with VUE and 3 control placentas were stained using immunohistochemistry with antibodies for CD3, CD4, CD8, CD68, CD163, perforin, granzyme B, granzyme K, and C5b-9. TUNEL assay analysis was also performed with these placentas. The percentage of cells that stained positive, CD163/CD68 ratio, percentage of C5b-9 positive area, and apoptosis index were quantified and compared between the inflammatory lesions of the VUE placentas, non-VUE inflammatory lesions of the VUE placentas, and control placentas.

RESULTS

The percentages of CD3, CD4, CD8 CD68, CD163, perforin, and granzyme B positive cells were significantly higher in the inflammatory lesions of the VUE placentas (p < 0.05). The intravillous CD163/CD68 ratio was higher in the inflammatory lesions compared with the non-inflammatory lesion of the VUE placentas (p < 0.05). The percentage of granzyme K-positive cells was not significantly different between the groups. C5b-9 deposition was higher in the inflammatory lesions of the VUE placentas (p < 0.05). TUNEL-positive cells were significantly higher in the inflammatory lesions of the VUE placentas (p < 0.05).

DISCUSSION

To the best of our knowledge, this is the first report to assess villous injury, especially from a viewpoint of villous apoptosis in VUE placentas. An activated perforin/granzyme pathway and C5b-9 are suggested as possible mechanisms of apoptosis.

Complement factor B activation in patients with preeclampsia

Preeclampsia is a leading cause of maternal and fetal morbidity and mortality. Bb, the active fragment of complement factor B (fB), has been reported to be a predictor of preeclampsia. However, conflicting results have been found by some investigators. We hypothesized that the disagreement in findings may be due to the racial/ethnic differences among various study groups, and that fB activation is significant in women of an ethnic minority with preeclampsia. We investigated the maternal and fetal levels of Bb (the activated fB fragment) in pregnant women of an ethnic minority with or without preeclampsia. We enrolled 291 pregnant women (96% of an ethnic minority, including 78% African-American). Thirteen percent of these were diagnosed with preeclampsia. Maternal venous blood was collected from all participants together with fetal umbilical cord blood samples from 154 deliveries in the 291 women. The results were analyzed using the Mann-Whitney U test and multivariate analyses. Maternal Bb levels were significantly higher in the preeclamptic group than in the nonpreeclamptic group. Levels of Bb in fetal cord blood were similar in both groups. Subgroup analyses of African-American patients' results confirmed the study hypothesis that there would be a significant increase in Bb in the maternal blood of the preeclamptic group and no increase in Bb in the fetal cord blood of this group. These results suggest that a maternal immune response through complement fB might play a role in the development of preeclampsia, particularly in African-American patients.

Neurokinin 3 receptor and phosphocholine transferase: missing factors for pathogenesis of C-reactive protein in preeclampsia

C-reactive protein (CRP), an innate immune mediator, is elevated in the circulation before symptoms in patients with preeclampsia, a severe hypertensive pregnancy disorder with high mortality and morbidity. However, the specific sources underlying increased CRP and the role of elevated CRP in preeclampsia are undefined. Here, we report that circulating CRP levels are significantly increased in a large cohort of normotensive pregnant individuals when compared with nulligravid women and is further increased in patients with preeclampsia. These findings led us to discover further that placental syncytiotrophoblasts are previously unrecognized cellular sources of CRP and underlie elevated CRP in normotensive pregnant women and the additional increase in patients with preeclampsia. Next, we demonstrated that injection of CRP induces preeclampsia features, including hypertension (157 mm Hg CRP treated versus 119 mm Hg control), proteinuria (35.0 mg/μg CRP treated versus 14.1 mg/μg control), kidney, and placental damage and increased levels of sFlt-1 in pregnant mice but not in nonpregnant mice. Our study implicates that phosphocholine transferase, a placental-specific enzyme post-translationally modifying neurokinin B, is essential for the pathogenic role of CRP in preeclampsia through activation of the neurokinin 3 receptor. Overall, our studies have provided significant new insight on the pathogenic role of CRP in preeclampsia and highlighted innovative therapeutic strategies.

Antepartum or immediate postpartum renal biopsies in preeclampsia/eclampsia of pregnancy: new morphologic and clinical findings

BACKGROUND

Preeclampsia (PE) and eclampsia remain leading causes of maternal and fetal mortality worldwide. The kidney is considered the first and most severely affected organ in women with PE/eclampsia. In this study, we analyzed new morphologic features of kidney biopsies and clinical findings in patients with PE or eclampsia at our hospital.

METHODS

Eight patients with PE/eclampsia underwent renal biopsies during the antepartum (3/8) or postpartum (5/8) period. Maternal clinical findings, major serological indices, neonatal outcomes, and renal histopathologic and immunofluorescent characteristics were reviewed for each case.

RESULTS

Most patients had abnormal serum cholesterol (8/8), triglyceride (6/8), albumin (7/8), and uric acid (5/8). The ratio of blood urea nitrogen (BUN) to serum creatinine (SCr) was elevated in all patients. Five of eight newborns survived. Various degrees of morphologic change were present in the renal glomeruli, and were associated with proteinuria. All patients had deposition of complement factor 4 (C4) in the renal glomeruli and seven had deposition of immunoglobulin M (IgM).

CONCLUSION

Endotheliosis, vacuolation of podocytes, proliferation of mesangial cells, and protein casts in the tubule lumens were found in the kidneys of women with PE/eclampsia. Immune depositions of C4 and IgM are major contributors to renal lesions in preeclamptic patients, whose neonates can generally survive. Eclampsia can occur without increased blood pressure.

Brief report: carboxypeptidase B serves as a protective mediator in osteoarthritis

OBJECTIVE

We previously demonstrated that carboxypeptidase B (CPB) protects against joint erosion in rheumatoid arthritis by inactivating complement component C5a. We also found that levels of CPB are abnormally high in the synovial fluid of individuals with another joint disease, osteoarthritis (OA). We undertook this study to investigate whether CPB plays a role in the pathogenesis of OA.

METHODS

We compared the development of OA in CPB-deficient (Cpb2(-/-) ) mice and wild-type mice by subjecting them to medial meniscectomy and histologically assessing cartilage damage, osteophyte formation, and synovitis in the stifle joints 4 months later. We measured levels of proCPB, proinflammatory cytokines, and complement components in synovial fluid samples from patients with symptomatic and radiographic knee OA. Finally, we used enzyme-linked immunosorbent assay, flow cytometry, and hemolytic assays to assess the effect of CPB on formation of membrane attack complex (MAC)-a complement effector critical to OA pathogenesis.

RESULTS

Cpb2(-/-) mice developed dramatically greater cartilage damage than did wild-type mice (P < 0.01) and had a greater number of osteophytes (P < 0.05) and a greater degree of synovitis (P < 0.05). In synovial fluid samples from OA patients, high levels of proCPB were associated with high levels of proinflammatory cytokines and complement components, and levels of proCPB correlated positively with those of MAC. In in vitro complement activation assays, activated CPB suppressed the formation of MAC as well as MAC-induced hemolysis.

CONCLUSION

Our data suggest that CPB protects against inflammatory destruction of the joints in OA, at least in part by inhibiting complement activation.

14th International Congress on Antiphospholipid Antibodies Task Force report on obstetric antiphospholipid syndrome

Pregnancy morbidity is one of the clinical manifestations used for classification criteria of antiphospholipid syndrome (APS). During the 14th International Congress on Antiphospholipid Antibodies (aPL), a Task Force with internationally-known experts was created to carry out a critical appraisal of the literature available regarding the association of aPL with obstetric manifestations present in actual classification criteria (recurrent early miscarriage, fetal death, preeclampsia and placental insufficiency) and the quality of the evidence that treatment(s) provide benefit in terms of avoiding recurrent adverse obstetric outcomes. The association of infertility with aPL and the effectiveness of the treatment of patients with infertility and positive aPL was also investigated. This report presents current knowledge and limitations of published studies regarding pregnancy morbidity, infertility and aPL, identifying areas that need better investigative efforts and proposing how critical flaws could be avoided in future studies, as suggested by participants of the Task Force. Except for fetal death, there are limitations in the quality of the data supporting the association of aPL with obstetric complications included in the current APS classification criteria. Recommended treatments for all pregnancy morbidity associated to APS also lack well-designed studies to confirm its efficacy. APL does not seem to be associated with infertility and treatment does not improve the outcomes in infertile patients with aPL. In another section of the Task Force, Dr. Jane Salmon reviewed complement-mediated inflammation in reproductive failure in APS, considering new therapeutic targets to obstetric APS (Ob APS).

Urinary excretion of C5b-9 in severe preeclampsia: tipping the balance of complement activation in pregnancy

The complement cascade is activated in normal pregnancy, and excessive complement activation propagates the systemic inflammatory response in severe preeclampsia. Consequently, biomarkers of complement dysregulation may be useful for prediction or treatment of disease. Because renal damage with proteinuria is a characteristic pathological feature of preeclampsia, we hypothesized that complement markers in urine, rather than plasma, could better reflect complement dysregulation in disease. To investigate this, we performed a case-control study of pregnant women, enrolling 25 cases with severe preeclampsia, 25 controls with chronic hypertension, and 25 healthy controls without hypertension matched by gestational age and parity. Subjects were recruited from the Brigham and Women's Hospital from March 2012 to March 2013. Urine and blood samples were collected on the day of enrollment, with complement activation (C3a, C5a, and C5b-9) measured by ELISA. Severe preeclampsia was associated with marked elevations in urinary C5b-9 (median [interquartile range], 4.3 [1.2-15.1] ng/mL) relative to subjects with chronic hypertension (0 [0-0]) and healthy controls (0 [0-0]; P<0.0001). Urinary excretion of C5b-9 was detected in 96% of cases with severe preeclampsia, 12% of controls with chronic hypertension, and 8% of healthy controls. Cases were also notable for significantly greater urinary excretion of C3a and C5a. Plasma levels of C5a and C5b-9, but not C3a, were increased in the cases with severe preeclampsia compared with healthy controls; however, they did not distinguish preeclampsia from chronic hypertension, supporting our hypothesis that complement markers in urine, rather than plasma, better reflect complement dysregulation. Complement inhibition is an intriguing treatment option for patients with severe preeclampsia.

Pericellular oxygen concentration of cultured primary human trophoblasts

INTRODUCTION

Oxygen is pivotal in placental development and function. In vitro culture of human trophoblasts provides a useful model to study this phenomenon, but a hotly debated issue is whether or not the oxygen tension of the culture conditions mimics in vivo conditions. We tested the hypothesis that ambient oxygen tensions in culture reflect the pericellular oxygen levels.

METHODS

We used a microelectrode oxygen sensor to measure the concentration of dissolved oxygen in the culture medium equilibrated with 21%, 8% or <0.5% oxygen.

RESULTS

The concentration of oxygen in medium without cells resembled that in the ambient atmosphere. The oxygen concentration present in medium bathing trophoblasts was remarkably dependent on the depth within the medium where sampling occurred, and the oxygen concentration within the overlying atmosphere was not reflected in medium immediately adjacent to the cells. Indeed, the pericellular oxygen concentration was in a range that most would consider severe hypoxia, at ≤0.6% oxygen or about 4.6 mm Hg, when the overlying atmosphere was 21% oxygen.

CONCLUSIONS

We conclude that culture conditions of 21% oxygen are unable to replicate the pO(2) of 40-60 mm Hg commonly attributed to the maternal blood in the intervillous space in the second and third trimesters of pregnancy. We further surmise that oxygen atmospheres in culture conditions between 0.5% and 21% provide different oxygen fluxes in the immediate pericellular environment yet can still yield insights into the responses of human trophoblast to different oxygen conditions.

Defective complement inhibitory function predisposes to renal disease

The role of the complement system in mediating human renal disease has long been recognized in immune-complex excess syndromes such as systemic lupus erythematosus and in dense deposit disease in which no immunoglobulin (Ig) is present. Over the past 15 years, mutations in complement regulatory genes have been demonstrated to predispose to thrombotic microangiopathies including atypical hemolytic uremic syndrome, C3 and C1q glomerulopathies, and preeclampsia. Excessive complement activation on an endothelial cell, due to either an autoantibody or a regulatory protein deficiency, sets up a procoagulant state in these diseases as well as in the antiphospholipid syndrome. Knowledge of the genes involved and the functional consequences of alterations in their structure has led to therapy that blocks complement activation.

Complement factors are secreted in human follicular fluid by granulosa cells and are possible oocyte maturation factors

AIMS

In this study, we identify components of the complement system present in human follicular fluid that affect oocyte development and maturation.

MATERIAL AND METHODS

Using bottom-up liquid chromatography/mass spectrometry/mass spectrometry, we identified complement factors as consistently present in human follicular fluid from 15 different subjects.

RESULTS

According to our gene-chip data, these complement factors are actively produced by granulosa cells.

CONCLUSIONS

By applying the computational Ingenuity Pathway Analysis software and database we have identified complement pathways that play a role in oocyte maturation and follicular development.

Autoantibody-mediated complement C3a receptor activation contributes to the pathogenesis of preeclampsia

Preeclampsia (PE) is a prevalent life-threatening hypertensive disorder of pregnancy associated with increased complement activation. However, the causative factors and pathogenic role of increased complement activation in PE are largely unidentified. Here we report that a circulating maternal autoantibody, the angiotensin II type 1 receptor agonistic autoantibody, which emerged recently as a potential pathogenic contributor to PE, stimulates deposition of complement C3 in placentas and kidneys of pregnant mice via angiotensin II type 1 receptor activation. Next, we provide in vivo evidence that selectively interfering with C3a signaling by a complement C3a receptor-specific antagonist significantly reduces hypertension from 167±7 to 143±5 mm Hg and proteinuria from 223.5±7.5 to 78.8±14.0 μg of albumin per milligram creatinine (both P<0.05) in angiotensin II type 1 receptor agonistic autoantibody-injected pregnant mice. In addition, we demonstrated that complement C3a receptor antagonist significantly inhibited autoantibody-induced circulating soluble fms-like tyrosine kinase 1, a known antiangiogenic protein associated with PE, and reduced small placental size with impaired angiogenesis and intrauterine growth restriction. Similarly, in humans, we demonstrate that C3 deposition is significantly elevated in the placentas of preeclamptic patients compared with normotensive controls. Lastly, we show that complement C3a receptor activation is a key mechanism underlying autoantibody-induced soluble fms-like tyrosine kinase 1 secretion and decreased angiogenesis in cultured human villous explants. Overall, we provide mouse and human evidence that angiotensin II type 1 receptor agonistic autoantibody-mediated activation contributes to elevated C3 and that complement C3a receptor signaling is a key mechanism underlying the pathogenesis of the disease. These studies are the first to link angiotensin II type 1 receptor agonistic autoantibody with complement activation and to provide important new opportunities for therapeutic intervention in PE.

Unilateral uterine ischemia/reperfusion-induced bilateral fetal loss and fetal growth restriction in a murine model require intact complement component 5

The role of complement in ischemia/reperfusion-induced fetal growth restriction and fetal loss is unknown. C5-deficient or wild type timed-pregnant mice were subjected to unilateral uterine ischemia/reperfusion on gestation day 13, either by (1) partial flow restriction by right ovarian artery clamping for 30 min, or (2) total flow restriction by clamping both ovarian and uterine arteries for 5 min. Ischemia/reperfusion-challenged pregnancy outcomes were compared to sham-operated controls 5 days later. Ischemia/reperfusion-treated wild type mice exhibited significantly increased bilateral fetal loss, which was greater in total flow restriction than in partial flow restriction, and decreased fetal weights, which were the same in total flow restriction and partial flow restriction for the surviving fetuses. Placental weights were unchanged by treatments. Ischemia/reperfusion increased uterine, but not placental, myeloperoxidase activity, which correlated with fetal loss. In contrast, C5-deficient mice were protected from both fetal growth restriction and fetal loss, and exhibited no increase in myeloperoxidase activity. These results demonstrate that unilateral uterine ischemia/reperfusion results in bilateral fetal loss and fetal growth restriction, mediated by a systemic mechanism. In the current model, this pathological process is completely dependent on intact complement component 5.

Biomarkers of coagulation, inflammation, and angiogenesis are independently associated with preeclampsia

PROBLEM

Although preeclampsia has been associated with inflammation, coagulation, and angiogenesis, their correlation and relative contribution are unknown.

METHOD OF STUDY

About 114 women with preeclampsia, 31 with early onset (EOP) and 83 with late onset preeclampsia (LOP), and 100 normal pregnant controls were included. A broad panel of 32 biomarkers reflecting coagulation, inflammation, and angiogenesis was analyzed.

RESULTS

Preeclampsia was associated with decreased antithrombin, IL-4 and placental growth factor levels and with increased C3a, pentraxin-3, and sFlt-1 levels, with more marked differences in the EOP group. The Th1-associated chemokines CXCL10 and CXCL11 were significantly higher in the preeclampsia and EOP group than in controls, respectively. No correlations between the biomarkers were found in preeclampsia. Multivariate logistic regression tests confirmed the results.

CONCLUSIONS

Cytokines, chemokines and complement activation seem to be part of a Th1-like inflammatory reaction in preeclampsia, most pronounced in EOP, where chemokines may be more useful than cytokines as biomarkers. Biomarkers were not correlated suggesting partly independent or in time separated mechanisms.

Late-onset preeclampsia is associated with an imbalance of angiogenic and anti-angiogenic factors in patients with and without placental lesions consistent with maternal underperfusion

OBJECTIVE

An imbalance between maternal angiogenic/anti-angiogenic factors concentrations has been observed in preeclampsia (PE) and other obstetrical syndromes. However, the frequency of pathologic findings in the placenta and the changes in maternal plasma angiogenic/anti-angiogenic factor concentrations differ between late- and early-onset PE. The aim of this study was to determine if the maternal plasma concentrations of placental growth factor (PlGF), soluble endoglin (sEng), and soluble vascular endothelial growth factor receptor-1 and 2 (sVEGFR-1 and sVEGFR-2) are different in late-onset PE with and without placental pathologic findings consistent with maternal underperfusion.

STUDY DESIGN

A cross-sectional study was conducted including 64 uncomplicated women and 66 women with late-onset PE (>34 weeks) who had blood samples and placenta available for pathologic examination. Patients with late-onset PE were divided into those with and without placental histologic findings consistent with maternal underperfusion as proposed by the Society for Pediatric Pathology. Maternal plasma concentrations of PlGF, sEng, sVEGFR-1 and sVEGRF-2 were determined by ELISA. Non-parametric statistics were used for analysis.

RESULTS

1) the prevalence of placental histological findings consistent with maternal underperfusion among women with late-onset PE was higher than that of those with an uncomplicated pregnancy (47% (31/66) vs. 7.8% (5/64), respectively; p < 0.01); 2) patients with late-onset PE and histological findings consistent with maternal underperfusion had a significantly lower median plasma concentration of PlGF, plasma PlGF/sVEGFR-1 ratio and plasma PlGF/sEng ratio than those with late-onset PE without placental underperfusion lesions (each p < 0.05); 3) the most common pathological findings in the placenta of patient with PE were lesions consistent with villous changes (77%, 24/31); and 4) isolated vascular lesions in the placenta were found only in 2 cases (6.5%), and the rest had a combination of villous and vascular lesions.

CONCLUSIONS

Nearly half of the patients with late-onset PE have placental lesions consistent with maternal underperfusion. These lesions are associated with an imbalance in the maternal concentration of angiogenic/anti-angiogenic factors. We propose that there is a link between maternal underperfusion and an anti-angiogenic state characterized by the changes in the concentrations of angiogenic and anti-angiogenic factors in women with late onset PE.

Prepregnancy obesity and complement system activation in early pregnancy and the subsequent development of preeclampsia

OBJECTIVE

We hypothesized that women who are obese before they become pregnant and also have elevations of complement Bb and C3a in the top quartile in early pregnancy would have the highest risk of preeclampsia compared with a referent group of women who were not obese and had levels of complement less than the top quartile.

STUDY DESIGN

This was a prospective study of 1013 women recruited at less than 20 weeks' gestation. An EDTA-plasma sample was obtained, and complement fragments were measured using enzyme-linked immunosorbent assays. The data were analyzed using univariable and multivariable logistic regression analysis.

RESULTS

Women who were obese with levels of Bb or C3a in the top quartile were 10.0 (95% confidence interval, 3.3-30) and 8.8 (95% confidence interval, 3-24) times, respectively, more likely to develop preeclampsia compared with the referent group.

CONCLUSION

We demonstrate a combined impact of obesity and elevated complement on the development of preeclampsia.

Membrane attack by complement: the assembly and biology of terminal complement complexes

Complement system activation plays an important role in both innate and acquired immunity. Activation of the complement and the subsequent formation of C5b-9 channels (the membrane attack complex) on the cell membranes lead to cell death. However, when the number of channels assembled on the surface of nucleated cells is limited, sublytic C5b-9 can induce cell cycle progression by activating signal transduction pathways and transcription factors and inhibiting apoptosis. This induction by C5b-9 is dependent upon the activation of the phosphatidylinositol 3-kinase/Akt/FOXO1 and ERK1 pathways in a Gi protein-dependent manner. C5b-9 induces sequential activation of CDK4 and CDK2, enabling the G1/S-phase transition and cellular proliferation. In addition, it induces RGC-32, a novel gene that plays a role in cell cycle activation by interacting with Akt and the cyclin B1-CDC2 complex. C5b-9 also inhibits apoptosis by inducing the phosphorylation of Bad and blocking the activation of FLIP, caspase-8, and Bid cleavage. Thus, sublytic C5b-9 plays an important role in cell activation, proliferation, and differentiation, thereby contributing to the maintenance of cell and tissue homeostasis.

Preeclampsia, hypoxia, thrombosis, and inflammation

Reductions in uteroplacental flow initiate a cascade of molecular effects leading to hypoxia, thrombosis, inflammation, and endothelial cell dysfunction resulting in untoward pregnancy outcomes. In this review, we detail these effects and their relationship to preeclampsia (PE) and intrauterine growth restriction (IUGR).

Too Much of a Good Thing at the Site of Tissue Injury: The Instructive Example of the Complement System Predisposing to Thrombotic Microangiopathy

The interplay between the complement and coagulation systems is just beginning to be explored and characterized. This interaction, however, is ancient. For example, if endotoxin is added to the hemolymph of the horseshoe crab, a protease is activated that triggers both the coagulation and complement systems. However, in extant mammals, these 2 cascades have diverged. These infamous “terrible C's” are the scourge of many a medical student (and possibly even a few hematologists). They also are intimately involved in the pathophysiology of thrombomicroangiopathies (TMAs). The complement system generates a procoagulant microenvironment and the coagulation system forms a clot in the renal microvasculature, and thus the 2 systems are partners in mediating multiple pathophysiological conditions.

Placental dysfunction and fetal programming: the importance of placental size, shape, histopathology, and molecular composition

Normal function of the placenta is pivotal for optimal fetal growth and development. Fetal programming commonly is associated with placental dysfunction that predisposes to obstetric complications and suboptimal fetal outcomes. We consider several clinical phenotypes for placental dysfunction that likely predispose to fetal programming. Some of these reflect abnormal development of the chorioallantoic placenta in size, shape, or histopathology. Others result when exogenous stressors in the maternal environment combine with maladaptation of the placental response to yield small placentas with limited reserve, as typical of early-onset intrauterine growth restriction and preeclampsia. Still others reflect epigenetic changes, including altered expression of imprinted genes, altered enzymatic activity, or altered efficiencies in nutrient transport. Although the human placenta is a transient organ that persists only 9 months, the effects of this organ on the offspring remain for a lifetime.