Dysregulated complement activation as a common pathway of injury in preeclampsia and other pregnancy complications

Variations of C3 and C4 Before and During Pregnancy in Systemic Lupus Erythematosus: Association With Disease Flares and Obstetric Outcomes

OBJECTIVE

To analyze complement level variations in systemic lupus erythematosus (SLE) pregnancies, focusing on disease flares and obstetric complications.

METHODS

SLE pregnancies prospectively followed by multidisciplinary teams from 1987 to 2018 in 2 Italian rheumatology centers were retrospectively analyzed. As reference, pregnancy-modified ranges of normal levels of C3 and C4 were derived from 175 pregnancies from the general obstetric population (GOP), as previously described by our group.

RESULTS

Two hundred forty-six pregnancies in 172 patients with SLE were analyzed. Eighty-nine percent were live births. Thirty-five flares were recorded in 30 pregnancies (12.2%) and obstetric complications occurred in 47 pregnancies (19.1%) including 27 pregnancy losses, 11 severely preterm births (2 resulting in perinatal death), and 15 hypertensive disorders. C3 and C4 levels were higher in the GOP than in patients with SLE, at any time point. C3 and C4 levels progressively increased during pregnancy in both GOP and SLE pregnancies without flare and obstetric complications, whereas this physiological increase was not observed in pregnancies with flares or obstetric complications. A significantly higher frequency of low C4 was found in pregnancies with flares (at preconception and in each trimester) and preterm births (at preconception). In multivariate analysis, low C4 at preconception was associated with flares (odds ratio 13.81, 95% CI 3.10-61.43, P < 0.001).

CONCLUSION

Low C4 at preconception was found to be an independent risk factor for SLE flare during pregnancy. Not only C3 and C4 levels but also their variations should be observed, as their failure to increase can be useful to predict risk of complications and suggest closer monitoring.

Bioactive lipid mediators in plasma are predictors of preeclampsia irrespective of aspirin therapy

There are few early biomarkers to identify pregnancies at risk of preeclampsia (PE) and abnormal placental function. In this cross-sectional study, we utilized targeted ultra-performance liquid chromatography-ESI MS/MS and a linear regression model to identify specific bioactive lipids that serve as early predictors of PE. Plasma samples were collected from 57 pregnant women prior to 24-weeks of gestation with outcomes of either PE (n = 26) or uncomplicated term pregnancies (n = 31), and the profiles of eicosanoids and sphingolipids were evaluated. Significant differences were revealed in the eicosanoid, (±)11,12 DHET, as well as multiple classes of sphingolipids; ceramides, ceramide-1-phosphate, sphingomyelin, and monohexosylceramides; all of which were associated with the subsequent development of PE regardless of aspirin therapy. Profiles of these bioactive lipids were found to vary based on self-designated race. Additional analyses demonstrated that PE patients can be stratified based on the lipid profile as to PE with a preterm birth linked to significant differences in the levels of 12-HETE, 15-HETE, and resolvin D1. Furthermore, subjects referred to a high-risk OB/GYN clinic had higher levels of 20-HETE, arachidonic acid, and Resolvin D1 versus subjects recruited from a routine, general OB/GYN clinic. Overall, this study shows that quantitative changes in plasma bioactive lipids detected by ultra-performance liquid chromatography-ESI-MS/MS can serve as an early predictor of PE and stratify pregnant people for PE type and risk.

Alternative pathway activation in pregnancy, a measured amount "complements" a successful pregnancy, too much results in adverse events

During pregnancy, the maternal host must adapt in order to enable growth of the fetus. These changes affect all organ systems and are designed both to protect the fetus and to minimize risk to the mother. One of the most prominent adaptations involves the immune system. The semi-allogenic fetoplacental unit has non-self components and must be protected against attack from the host. This requires both attenuation of adaptive immunity and protection from innate immune defense mechanisms. One of the key innate immune players is complement, and it is important that the fetoplacental unit is not identified as non-self and subjected to complement attack. Adaptation of the complement response must, however, be managed in such a way that maternal protection against infection is not compromised. As the complement system also plays a significant facilitating role in many of the stages of a normal pregnancy, it is also important that any necessary adaptation to accommodate the semi-allogenic aspects of the fetoplacental unit does not compromise this. In this review, both the physiological role of the alternative pathway of complement in facilitating a normal pregnancy, and its detrimental participation in pregnancy-specific disorders, are discussed.

Adipsin of the Alternative Complement Pathway Is a Potential Predictor for Preeclampsia in Early Pregnancy

Objective

The concentrations of complement proteins (adipsin, C3a, and C5a) and soluble endoglin (sENG) in the plasma were measured in this study, and their value as early-pregnancy predictors and potential diagnostic marker of preeclampsia was assessed, respectively.

Experimental Design

Plasma samples were obtained from healthy and preeclampsia pregnant women before delivery for a cross-sectional study. Plasma samples were collected from healthy and preeclampsia pregnant women throughout pregnancy and postpartum for a follow-up study. Enzyme-linked immunosorbent assays were used to detect plasma levels of several complement proteins (adipsin, C3a, and C5a) and sENG.

Results

The plasma levels of adipsin, C5a, and sENG were significantly increased before delivery in pregnant women with preeclampsia. During pregnancy, the plasma adipsin, C5a, and sENG levels were increased from the third trimester in healthy pregnant women; plasma adipsin levels remained stable after delivery, while C3a levels increased in the second trimester and remained stable afterward. Furthermore, levels of adipsin, C5a, and sENG were higher in preeclampsia patients at different stages of pregnancy; the C3a level presents a similar change and no difference was found in the third trimester. In the first trimester, receiver-operating curve (ROC) curve analysis showed that adipsin (AUC, 0.83 ± 0.06, P=0.001) and sENG (AUC, 0.74 ± 0.09, P=0.021) presented high value as predictors of early pregnancy.

Conclusions

Adipsin is likely a novel plasma biomarker to monitor the increased risk of preeclampsia in early pregnancy. Moreover, the increased plasma levels of adipsin, C5a, and sENG before delivery may be associated with preeclampsia.

Diseases and conditions that impact maternal and fetal health and the potential for nanomedicine therapies

Maternal mortality rates in the United States have steadily increased since 1987 to the current rate of over 16 deaths per 100,000 live births. Whereas most of these deaths are related to an underlying condition, such as cardiovascular disease, many pregnant women die from diseases that emerge as a consequence of pregnancy. Both pre-existing and emergent diseases and conditions are difficult to treat in pregnant women because of the potential harmful effects of the treatment on the developing fetus. Often the health of the woman and the health of the baby are at odds and must be weighed against each other when medical treatment is needed, frequently leading to iatrogenic preterm birth. However, the use of engineered nanomedicines has the potential to fill the treatment gap for pregnant women. This review describes several conditions that may afflict pregnant women and fetuses and introduces how engineered nanomedicines may be used to treat these illnesses. Although the field of maternal-fetal nanomedicine is in its infancy, with additional research and development, engineered nanotherapeutics may greatly improve outcomes for pregnant women and their offspring in the future.

Plasma glycated CD59 (gCD59), a novel biomarker for the diagnosis, management and follow up of women with Gestational Diabetes (GDM) - protocol for prospective cohort study

BACKGROUND

The prevalence of Gestational Diabetes (GDM) is rising and with it the number of mothers and children at risk of adverse outcomes. As treatment has been shown to reduce adverse events, it is imperative that we identify all at-risk pregnant women. In Ireland, the national standard of care is selective screening with a 2-hour 75 g oral glucose tolerance test (OGTT). Aiming for universal screening is of utmost importance but this is difficult given the length, the unfeasibility and impracticability of the OGTT. We aim to assess if the novel biomarker glycated CD59 (gCD59) is a suitable contender for the OGTT in identifying women with GDM.

METHODS

In this prospective cohort study, the study participants will be consecutive pregnant women at Galway University Hospital, Galway, Ireland. Samples for the plasma gCD59 biomarker will be taken together with routine bloods at the first antenatal visit, at weeks 24-28 at the time of routine 75 g OGTT, in trimester 3- and 12-weeks post-partum for women with GDM while having their routine post-partum 75 g OGTT. The constructed database will contain baseline information on each study participant, baseline laboratory data, follow-up laboratory data and pregnancy related outcomes. We aim to recruit a total of 2,000 participants over the project period and with a national GDM prevalence of 12-13%, we will have 240-260 subjects who meet OGTT criteria for GDM. Following regional prevalence, we expect to have 34-37 women who will develop either diabetes or pre-diabetes in the early post-partum period. The sensitivity and specificity of plasma gCD59 to predict the results of the OGTT will be assessed using nonparametric estimates of the receiver operating characteristic (ROC) curves and respective area under the ROC curve (AUROC).

DISCUSSION

A body of clinical and experimental evidence supports a link between the complement system, complement regulatory proteins, and the pathogenesis of diabetes complications. Building on this research, our study plans to look at the plasma gCD59 capacity to classify pregnant women with normal or abnormal glucose tolerance but also to assess if plasma gCD59 can be used as an early predictor for GDM, for adverse pregnancy outcomes and/or post-partum glucose intolerance.

Pregnancy immune tolerance at the maternal-fetal interface

Pregnancy is a natural process that poses an immunological challenge because non-self fetus must be accepted. During the pregnancy period, the fetus as 'allograft' inherits maternal and also paternal antigens. For successful and term pregnancy, the fetus is tolerated and nurtured enjoying immune privileges that minimize the risk of being rejected by maternal immune system. Multiple mechanisms contribute to tolerate the semi-allogeneic fetus. Here, we summarize the recent progresses on how the maternal immune system actively collaborates to maintain the immune balance and maternal-fetal tolerance.

Acute kidney injury in pregnancy

PURPOSE OF REVIEW

Pregnancy-related acute kidney injury (Pr-AKI) is associated with increased maternal and fetal morbidity and mortality and remains a large public health problem.

RECENT FINDINGS

Pr-AKI incidence has globally decreased over time for the most part. However, the cause presents a disparity between developing and developed countries, reflecting differences in socioeconomic factors and healthcare infrastructure - with the noteworthy outlier of increased incidence in the United States and Canada. Although Pr-AKI can be secondary to conditions affecting the general population, in most cases it is pregnancy specific. Septic abortion, hyperemesis gravidarum, and hemorrhage have become less prevalent with access to healthcare but are being displaced by thrombotic microangiopathies, such as preeclampsia, hemolysis, elevated liver enzymes, low platelets syndrome, thrombotic thrombocytopenic purpura, and pregnancy-associated hemolytic-uremic syndromes, as well as acute fatty liver of pregnancy. Understanding these conditions plays a pivotal role in the timely diagnosis and enhancement of therapeutic approaches.

SUMMARY

In this review, we focus on the renal physiology of the pregnancy, epidemiology, and specific conditions known to cause Pr-AKI, summarizing diagnostic definition, insights in pathophysiology, clinical considerations, and novel treatment approaches, thus providing the reader a framework of clinically relevant information for interdisciplinary management.

Evidence for regulation of the complement system during pregnancy being ancient and conserved in mammals

Here we demonstrate that regulation of the Complement (C') components of the immune system is an ancient and conserved feature of mammalian pregnancy. Transcript levels were reduced for complement components C3 and C4 throughout pregnancy in a marsupial, Monodelphis domestica. Downstream C' component transcripts were significantly less abundant relative to non-pregnant controls at the start of pregnancy but increased during late pregnancy, in some cases peaking close to parturition. These results are consistent with observations in human pregnancy that deposition of C5 through C9 on fetal membranes is associated with labor and parturition. Complement regulators CD46 and CD59 are present at the fetomaternal interface during M. domestica pregnancy as well, implying regulation of C' effector mechanisms is necessary for maintenance of normal marsupial pregnancy. Collectively these results support regulating the complement system may have contributed to the transition from oviparity to viviparity in mammals over 165 million years ago.

Effect of hypocomplementemia on perinatal outcomes of pregnancies with autoimmune disorders

OBJECTIVE

To demonstrate the effect of preconceptional complement levels on perinatal outcomes of pregnancies with autoimmune disorders.

METHODS

Pregnant women with autoimmune disorders (autoimmune disease and/or autoimmune antibody positivity) who were screened for complement levels (C3 and C4) prior to their pregnancies were enrolled in a special antenatal care program. These patients were administered low-dose low-molecular-weight heparin (enoxaparine, 1 × 2000 Anti-XA IU/0.2 mL/day), low-dose salysilic acid (100 mg/day) and low-dose corticosteroid (methylprednisolone, 1 × 4 mg/day orally) as soon as their pregnancies were confirmed according to the institutional protocol. We have compared hypo- and normocomplement pregnancies with autoimmune disorders in terms of their obstetric and perinatal outcomes. We have also used Beksac Obstetric Index (BOI) which is "[living child + (π/10)]/gravidity" for the comparison of their previous obstetric histories.

RESULTS

Obstetric and neonatal outcomes showed no significant difference between hypocomplement patients (n= 38) and control group (n= 157) (p> 0.05). "Composite obstetric and perinatal adverse outcome" rates were 26.2% and 27.3% in study and control groups, respectively (p> 0.05). BOI was significantly lower in hypocomplement patients (p: 0.002). Then, we have classified hypocomplement patients into 3 subgroups according to the type of complement (C3, C4 or both). Comparison inbetween these groups revealed no statistical significance in any of the analyzed parameters (p> 0.05).

CONCLUSION

Low complement levels in pregnant women with autoimmune disorders may be associated with gestational problems and poor obstetric history. Immunomodulatory treatment modalities such as ours may be beneficial for improving the obstetric and neonatal outcomes.

Thromboinflammatory changes in plasma proteome of pregnant women with PCOS detected by quantitative label-free proteomics

Polycystic ovary syndrome (PCOS) is the most common endocrinological disorder of fertile-aged women. Several adverse pregnancy outcomes and abnormalities of the placenta have been associated with PCOS. By using quantitative label-free proteomics we investigated whether changes in the plasma proteome of pregnant women with PCOS could elucidate the mechanisms behind the pathologies observed in PCOS pregnancies. A total of 169 proteins with ≥2 unique peptides were detected to be differentially expressed between women with PCOS (n = 7) and matched controls (n = 20) at term of pregnancy, out of which 35 were significant (p-value < 0.05). A pathway analysis revealed that networks related to humoral immune responses, inflammatory responses, cardiovascular disease and cellular growth and proliferation were affected by PCOS. Classification of cases and controls was carried out using principal component analysis, orthogonal projections on latent structure-discriminant analysis (OPLS-DA), hierarchical clustering, self-organising maps and ROC-curve analysis. The most significantly enriched proteins in PCOS were properdin and insulin-like growth factor II. In the dataset, properdin had the best predictive accuracy for PCOS (AUC = 1). Additionally, properdin abundances correlated with AMH levels in pregnant women.

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.

Inflammation-The role of ATP in pre-eclampsia

Sterile inflammation may be initiated by molecules in the host organism that signal "damage" or "danger" also known as danger-associated molecular pattern (DAMPs). In pre-eclampsia (PE), a variety of DAMPs may be involved in the etiology or exacerbation of the disorder. Adenosine 5'-triphosphate (ATP) is a key intracellular energy molecule as well as a ligand for purinergic receptors. In humans, under physiological conditions, extracellular ATP (eATP) levels are distinctly low, but can rise to several hundred fold when cells become injured, stressed, or even necrotic. This often initiates a sterile inflammatory response with eATP acting as a DAMP. Extracellular ATP and its derivative nucleotides synthetized by endonucleotidases exhibit many of their effects through purinergic receptors, via inflammatory cascades and the production of proinflammatory molecules. This is clearly seen in the P2X₇ gated receptor, which is linked to release of cytokines of the interleukin-1 family. Considering its fundamental role in innate immunity, an imbalance of P2X₇ receptor activation may lead to deleterious effects in the coordination of placental vessel tone via the synthesis of various proinflammatory cytokines. This review explores the implication of DAMPs, specifically ATP and uric acid in the inflammation associated with PE.

Role of B1 and B2 lymphocytes in placental ischemia-induced hypertension

Preeclampsia is a prevalent pregnancy complication characterized by new-onset maternal hypertension and inflammation, with placental ischemia as the initiating event. Studies of others have provided evidence for the importance of lymphocytes in placental ischemia-induced hypertension; however, the contributions of B1 versus B2 lymphocytes are unknown. We hypothesized that peritoneal B1 lymphocytes are important for placental ischemia-induced hypertension. As an initial test of this hypothesis, the effect of anti-CD20 depletion on both B-cell populations was determined in a reduced utero-placental perfusion pressure (RUPP) model of preeclampsia. Anti-murine CD20 monoclonal antibody (5 mg/kg, Clone 5D2) or corresponding mu IgG2a isotype control was administered intraperitoneally to timed pregnant Sprague-Dawley rats on gestation day (GD)10 and 13. RUPP or sham control surgeries were performed on GD14, and mean arterial pressure (MAP) was measured on GD19 from a carotid catheter. As anticipated, RUPP surgery increased MAP and heart rate and decreased mean fetal and placental weight. However, anti-CD20 treatment did not affect these responses. On GD19, B-cell populations were enumerated in the blood, peritoneal cavity, spleen, and placenta with flow cytometry. B1 and B2 cells were not significantly increased following RUPP. Anti-CD20 depleted B1 and B2 cells in peritoneum and circulation but depleted only B2 lymphocytes in spleen and placenta, with no effect on circulating or peritoneal IgM. Overall, these data do not exclude a role for antibodies produced by B cells before depletion but indicate the presence of B lymphocytes in the last trimester of pregnancy is not critical for placental ischemia-induced hypertension.NEW & NOTEWORTHY The adaptive and innate immune systems are implicated in hypertension, including the pregnancy-specific hypertensive condition preeclampsia. However, the mechanism of immune system dysfunction leading to pregnancy-induced hypertension is unresolved. In contrast to previous reports, this study reveals that the presence of classic B2 lymphocytes and peritoneal and circulating B1 lymphocytes is not required for development of hypertension following third trimester placental ischemia in a rat model of pregnancy-induced hypertension.

Placental Galectins Are Key Players in Regulating the Maternal Adaptive Immune Response

Galectins are potent immunomodulators that regulate maternal immune responses in pregnancy and prevent the rejection of the semi-allogeneic fetus that also occurs in miscarriages. We previously identified a gene cluster on Chromosome 19 that expresses a subfamily of galectins, including galectin-13 (Gal-13) and galectin-14 (Gal-14), which emerged in anthropoid primates. These galectins are expressed only by the placenta and induce the apoptosis of activated T lymphocytes, possibly contributing to a shifted maternal immune balance in pregnancy. The placental expression of Gal-13 and Gal-14 is decreased in preeclampsia, a life-threatening obstetrical syndrome partly attributed to maternal anti-fetal rejection. This study is aimed at revealing the effects of Gal-13 and Gal-14 on T cell functions and comparing the expression of these galectins in placentas from healthy pregnancies and miscarriages. First-trimester placentas were collected from miscarriages and elective termination of pregnancies, tissue microarrays were constructed, and then the expression of Gal-13 and Gal-14 was analyzed by immunohistochemistry and immunoscoring. Recombinant Gal-13 and Gal-14 were expressed and purified, and their effects were investigated on primary peripheral blood T cells. The binding of Gal-13 and Gal-14 to T cells and the effects of these galectins on apoptosis, activation marker (CD25, CD71, CD95, HLA-DR) expression and cytokine (IL-1β, IL-6, IL-8, IL-10, IFNγ) production of T cells were examined by flow cytometry. Gal-13 and Gal-14 are primarily expressed by the syncytiotrophoblast at the maternal-fetal interface in the first trimester, and their placental expression is decreased in miscarriages compared to first-trimester controls. Recombinant Gal-13 and Gal-14 bind to T cells in a population- and activation-dependent manner. Gal-13 and Gal-14 induce apoptosis of Th and Tc cell populations, regardless of their activation status. Out of the investigated activation markers, Gal-14 decreases the cell surface expression of CD71, Gal-13 increases the expression of CD25, and both galectins increase the expression of CD95 on T cells. Non-activated T cells produce larger amounts of IL-8 in the presence of Gal-13 or Gal-14. In conclusion, these results show that Gal-13 and Gal-14 already provide an immunoprivileged environment at the maternal-fetal interface during early pregnancy, and their reduced expression is related to miscarriages.

The role of the complement system in HIV infection and preeclampsia

BACKGROUND

The complement system is a key component of the innate immune system that plays a vital role in host defense, maintains homeostasis and acts as a mediator of the adaptive immune response. The complement system could possibly play a role in the pathogenesis of HIV infection and preeclampsia (PE), both of which represent major causes of maternal death in South Africa.

RECENT FINDINGS

The relationship between PE and HIV infection is unclear as PE represents an exaggerated immune response, while HIV infection is associated with a decline in immune activity. Although the complement system works to clear and neutralize HIV, it could also enhance the infectivity of HIV by various other mechanisms. It has been suggested that the dysregulation of the complement system is associated with the development of PE.

CONCLUSION

There is currently a paucity of information on the combined effect of the complement system in HIV-associated PE. This review highlights the role of the complement system in the duality of HIV infection and PE and provides new insights into this relationship whilst also elucidating potential therapeutic targets.

Sialic acid is a critical fetal defense against maternal complement attack

The negatively charged sugar sialic acid (Sia) occupies the outermost position in the bulk of cell surface glycans. Lack of sialylated glycans due to genetic ablation of the Sia-activating enzyme CMP-sialic acid synthase (CMAS) resulted in embryonic lethality around day 9.5 post coitum (E9.5) in mice. Developmental failure was caused by complement activation on trophoblasts in Cmas-/- implants and was accompanied by infiltration of maternal neutrophils at the fetal-maternal interface, intrauterine growth restriction, impaired placental development, and a thickened Reichert's membrane. This phenotype, which shared features with complement receptor 1-related protein Y (Crry) depletion, was rescued in E8.5 Cmas-/- mice upon injection of cobra venom factor, resulting in exhaustion of the maternal complement component C3. Here we show that Sia is dispensable for early development of the embryo proper but pivotal for fetal-maternal immune homeostasis during pregnancy, i.e., for protecting the allograft implant against attack by the maternal innate immune system. Finally, embryos devoid of cell surface sialylation suffered from malnutrition due to inadequate placentation as a secondary effect.

Postpartum Renal Cortical Necrosis Is Associated With Atypical Hemolytic Uremic Syndrome in Developing Countries

Introduction

Pregnancy-related acute kidney injury is the most common cause of renal cortical necrosis (RCN). Atypical hemolytic uremic syndrome (aHUS) as a cause of RCN in pregnant/postpartum is underevaluated. In the current article, we describe a series of cases of pregnancy-related RCN.

Methods

All cases with acute kidney injury (AKI) in the setting of pregnancy and postpartum state were included. Diagnosis of RCN was made by contrast-enhanced computerized tomography (nonenhancing renal cortex, enhancing medulla, and no excretion of contrast medium) or on a renal biopsy. aHUS was diagnosed in the presence of microangiopathic hemolytic anemia (thrombocytopenia, elevated lactate dehydrogenase with schistocytes on peripheral smear examination, or low haptoglobin).

Results

A total of 21 (17.5%) patients presented with RCN during pregnancy, all in the postpartum state. Twenty patients (95.2%) showed microangiopathic hemolytic anemia consistent with HUS and 1 (4.8%) patient had biopsy-proven thrombotic microangiopathy. Low complement 3 or activation of an alternate complement pathway was seen in 9 of 15 patients in which it was done. At the end of 6 months, only 2 (9.5%) patients had partial recovery of renal functions, 5 (23.8%) patients died, and 14 remained (66.7%) on hemodialysis.

Conclusion

The clinical and laboratory features are highly suggestive of aHUS in more than three-fourths of cases with postpartum RCN. Investigations are needed to look for genetic abnormalities in the complement pathway.

The Immunogenetic Conundrum of Preeclampsia

Pregnancy is an immunological challenge to the mother. The fetal tissues including the placenta must be protected from activation of the maternal immune system. On the other hand, the placental tissue sheds into the maternal circulation and must be adequately identified and phagocytized by the maternal immune system. During a healthy pregnancy, numerous immunosuppressive processes take place that allow the allograft fetus to thrive under exposure to humoral and cellular components of the maternal immune system. Breakdown of immune tolerance may result in sterile inflammation and cause adverse pregnancy outcomes such as preeclampsia, a vascular disease of the pregnancy with unpredictable course and symptoms from several organs. Immunological incompatibility between mother and fetus is strongly indicated in preeclampsia. Recently, genetic factors linking immunological pathways to predisposition to preeclampsia have been identified. In this mini-review genetic variation in immunological factors are discussed in the context of preeclampsia. Specifically, we explore immunogenetic and immunomodulary mechanisms contributing to loss of tolerance, inflammation, and autoimmunity in preeclampsia.

Upregulation and release of soluble fms-like tyrosine kinase receptor 1 mediated by complement activation in human syncytiotrophoblast cells

PROBLEM

Antiangiogenic molecule soluble fms-like tyrosine kinase receptor 1 (sFLT1) released from trophoblast cells is associated with pregnancy-specific hypertensive disorder pre-eclampsia. Cause of elevated sFLT1 in pre-eclampsia patients is not well understood. Despite evidence of excess systemic and placental complement activation in pre-eclampsia patients, its role in pathophysiology is not clear. If the complement activation plays a role in upregulation and secretion of sFLT1 is not known.

METHOD OF STUDY

Human trophoblast cells were isolated from term placentas and allowed to syncytialize. Complement was activated in vitro at sublethal levels on syncytiotrophoblast cells. Effect of complement activation on expression and release of sFLT1 was assessed by comparing its levels in these cells with and without complement activation.

RESULTS

Sublethal level of complement activation on syncytialized human trophoblast cells induced upregulation of sFLT1 mRNA and protein. Complement also induced secretion of sFLT1 in a manner depending on degree of activation. Anaphylatoxins C3a induced upregulation but not the release of sFLT1. Release of terminal membrane attack complex (MAC) was associated with sFLT1 secretion.

CONCLUSION

Complement activation plays a major role in both the expression and secretion of sFLT1 from syncytial trophoblast cells. The terminal MAC complex is involved in its secretion. Increased levels of sFLT1 in pre-eclampsia patients may be due to complement-induced upregulation and secretion.

Disruption in the Regulation of Immune Responses in the Placental Subtype of Preeclampsia

Preeclampsia is a pregnancy-specific disorder, of which one of its major subtypes, the placental subtype is considered a response to an ischemic placental environment, impacting fetal growth and pregnancy outcome. Inflammatory immune responses have been linked to metabolic and inflammatory disorders as well as reproductive failures. In healthy pregnancy, immune regulatory mechanisms prevent excessive systemic inflammation. However, in preeclampsia, the regulation of immune responses is disrupted as a result of aberrant activation of innate immune cells and imbalanced differentiation of T-helper cell subsets creating a cytotoxic environment in utero. Recognition events that facilitate immune interaction between maternal decidual T cells, NK cells, and cytotrophoblasts are considered an indirect cause of the incomplete remodeling of spiral arteries in preeclampsia. The mechanisms involved include the activation of immune cells and the subsequent secretion of cytokines and placental growth factors affecting trophoblast invasion, angiogenesis, and eventually placentation. In this review, we focus on the role of excessive systemic inflammation as the result of a dysregulated immune system in the development of preeclampsia. These include insufficient control of inflammation, failure of tolerance toward paternal antigens at the fetal-maternal interface, and subsequent over- or insufficient activation of immune mediators. It is also possible that external stimuli, such as bacterial endotoxin, may contribute to the excessive systemic inflammation in preeclampsia by stimulating the release of pro-inflammatory cytokines. In conclusion, a disrupted immune system might be a predisposing factor or result of placental oxidative stress or excessive inflammation in preeclampsia. Preeclampsia can thus be considered a hyperinflammatory state associated with defective regulation of the immune system proposed as a key element in the pathological events of the placental subtype of this disorder.

Effect of nicotine on placental ischemia-induced complement activation and hypertension in the rat

Preeclampsia is a pregnancy-specific condition manifested by new-onset maternal hypertension with systemic inflammation, including increased innate immune system complement activation. While exact pathophysiology is unknown, evidence suggests that inadequate spiral artery invasion and resulting utero-placental insufficiency is the initiating event. Cigarette smoking during pregnancy decreases the risk of preeclampsia. Nicotine, a major component of cigarettes, stimulates the efferent cholinergic anti-inflammatory pathway through peripherally expressed nicotinic acetylcholine receptors (nAChR) and is known to attenuate ischemia-reperfusion injury in kidney and liver. Prior studies indicated that complement activation was critical for placental ischemia-induced hypertension in a rat model. Thus, it was hypothesized here that nicotine was responsible for the protective effect of cigarette smoking in preeclampsia and would attenuate placental ischemia-induced systemic complement activation and hypertension. The Reduced Utero-placental Perfusion Pressure (RUPP) model in the pregnant rat was employed to induce placental ischemia, resulting in complement activation, fetal resorptions, and hypertension. On gestation day (GD)14, nicotine (1 mg/kg) or saline was administered via subcutaneous injection prior to RUPP surgery and daily through GD18. On GD19, placental ischemia significantly increased mean arterial pressure (MAP) in saline injected animals. However, the placental ischemia-induced increase in blood pressure was not evident in nicotine-treated animals and nicotine treatment significantly increased MAP variability. Circulating C3a was measured as an indicator of complement activation and increased C3a in RUPP compared to Sham persisted with nicotine treatment, as did fetal resorptions. These data suggested to us that nicotine may contribute to the decreased risk of preeclampsia with cigarette smoking, but this protective effect was confounded by additional effects of nicotine on the cardiovascular system.

Timing and mechanism of conceptus demise in a complement regulatory membrane protein deficient mouse

PROBLEM

Crry is a widely expressed type 1 transmembrane complement regulatory protein in rodents which protects self-tissue by downregulating C3 activation. Crry^-/- concepti produced by Crry^+/-  × Crry^+/- matings are attacked by maternal complement system leading to loss before day 10. The membrane attack complex is not the mediator of this death. We hypothesized that the ability of C3b to engage the alternative pathway's feedback loop relatively unchecked on placental membranes induces the lesion yielding the demise of the Crry^-/- mouse.

METHOD OF STUDY

We investigated the basis of Crry^-/- conceptus demise by depleting maternal complement with cobra venom factor and blocking antibodies. We monitored their effects primarily by genotyping and histologic analyses.

RESULTS

We narrowed the critical period of the complement effect from 6.5 to 8.5 days post-coitus (dpc), which is immediately after the conceptus is exposed to maternal blood. Deposition by 5.5 dpc of maternal C3b on the placental vasculature lacking Crry^-/- yielded loss of the conceptus by 8.5 dpc. Fusion of the allantois to the chorion during placental assembly did not occur, fetal vessels originating in the allantois did not infiltrate the chorioallantoic placenta, the chorionic plate failed to develop, and the labyrinthine component of the placenta did not mature.

CONCLUSION

Our data are most consistent with the deposition of C3b being responsible for the failure of the allantois to fuse to the chorion leading to subsequent conceptus demise.

Acute Kidney Injury in Pregnancy: The Changing Landscape for the 21st Century

Pregnancy-related acute kidney injury (Pr-AKI) remains a large public health problem, with decreasing incidences in developing countries but seemingly increasing incidences in the United States and Canada. These epidemiologic changes are reflective of the advances in medical and obstetric care, as well as changes in underlying maternal risk factors. The risk factors associated with advanced maternal age, such as hypertension, diabetes, chronic kidney disease, and those associated with reproductive technologies such as multiple gestations, are increasing. Traditional causes of Pr-AKI, such as septic abortions and puerperal sepsis, have been replaced by hypertensive diseases, such as preeclampsia and thrombotic microangiopathies comprising thrombotic thrombocytopenic purpura (TTP) and atypical hemolytic uremic syndrome (aHUS). In this review, we discuss the global impact of Pr-AKI on maternal and fetal outcomes, the predominant etiologies, and key clinical features to distinguish diagnoses, such as preeclampsia/hemolysis elevated liver function test and low platelet (HELLP) syndrome, acute fatty liver disease of pregnancy (AFLP), and other thrombotic microangiopathies. New insights into the pathogenesis of preeclampsia, TTP/aHUS, and AFLP that have unearthed possible therapeutic targets are summarized. We also delve into special consideration needed to give to pyelonephritis and postobstructive causes of Pr-AKI. With each diagnosis, we offer the latest treatment recommendations, such as the positive reports from the use of eculizumab to treat aHUS. In the end, we hope to arm the clinician with the best tools to understand and address this morbid problem that does not seem to be disappearing.

Complement activation predicts adverse pregnancy outcome in patients with systemic lupus erythematosus and/or antiphospholipid antibodies

OBJECTIVE

Studies in mouse models implicate complement activation as a causative factor in adverse pregnancy outcomes (APOs). We investigated whether activation of complement early in pregnancy predicts APOs in women with systemic lupus erythematosus (SLE) and/or antiphospholipid (aPL) antibodies.

METHODS

The PROMISSE Study enrolled pregnant women with SLE and/or aPL antibodies (n=487) and pregnant healthy controls (n=204) at <12 weeks gestation and evaluated them monthly. APOs were: fetal/neonatal death, preterm delivery <36 weeks because of placental insufficiency or preeclampsia and/or growth restriction <5th percentile. Complement activation products were measured on serial blood samples obtained at each monthly visit.

RESULTS

APO occurred in 20.5% of SLE and/or aPL pregnancies. As early as 12-15 weeks, levels of Bb and sC5b-9 were significantly higher in patients with APOs and remained elevated through 31 weeks compared with those with normal outcomes. Moreover, Bb and sC5b-9 were significantly higher in patients with SLE and/or aPL without APOs compared with healthy controls. In logistic regression analyses, Bb and sC5b-9 at 12-15 weeks remained significantly associated with APO (OR_adj=1.41 per SD increase; 95% CI 1.06 to 1.89; P=0.019 and OR_adj=1.37 per SD increase; 95% CI 1.05 to 1.80; P=0.022, respectively) after controlling for demographic and clinical risk factors for APOs in PROMISSE. When analyses were restricted to patients with aPL (n=161), associations between Bb at 12-15 weeks and APOs became stronger (OR_adj=2.01 per SD increase; 95% CI 1.16 to 3.49; P=0.013).

CONCLUSION

In pregnant patients with SLE and/or aPL, increased Bb and sC5b-9 detectable early in pregnancy are strongly predictive of APOs and support activation of complement, particularly the alternative pathway, as a contributor to APOs.

Maternal and Fetal Outcomes of Pregnancies in Women with Atypical Hemolytic Uremic Syndrome

Atypical HUS (aHUS) is a disorder most commonly caused by inherited defects of the alternative pathway of complement, or the proteins that regulate this pathway, and life-threatening episodes of aHUS can be provoked by pregnancy. We retrospectively and prospectively investigated 27 maternal and fetal pregnancy outcomes in 14 women with aHUS from the Vienna Thrombotic Microangiopathy Cohort. Seven pregnancies (26%) were complicated by pregnancy-associated aHUS (p-aHUS), of which three appeared to be provoked by infection, bleeding, and curettage, and three individuals were considered to have preeclampsia/HELLP syndrome before the definitive diagnosis of p-aHUS was made. Mutations in genes that encode the complement alternative pathway proteins or the molecules that regulate this pathway were detected in 71% of the women, with no relationship to pregnancy outcome. Twenty-one pregnancies (78%) resulted in a live birth, two preterm infants were stillborn, and four pregnancies resulted in early spontaneous abortions. Although short-term renal outcome was good in most women, long-term renal outcome was poor; among the 14 women, four had CKD stage 1-4, five had received a renal allograft, and three were dialysis-dependent at study end. We prospectively followed nine pregnancies of four women and treated six of these pregnancies with prophylactic plasma infusions (one pregnancy resulted in p-aHUS, one intrauterine fetal death occurred, and seven pregancies were uneventful). Our study emphasizes the frequency of successful pregnancies in women with aHUS. Close monitoring of such pregnancies for episodes of thrombotic microangiopathy is essential but, the best strategy to prevent these episodes remains unclear.

Complement 5a-mediated trophoblasts dysfunction is involved in the development of pre-eclampsia

Pre‐eclampsia (PE) is a life‐threatening multisystem disorder leading to maternal and neonatal mortality and morbidity. Emerging evidence showed that activation of the complement system is implicated in the pathological processes of PE. However, little is known about the detailed cellular and molecular mechanism of complement activation in the development of PE. In this study, we reported that complement 5a (C5a) plays a pivotal role in aberrant placentation, which is essential for the onset of PE. We detected an elevated C5a deposition in macrophages and C5a receptor (C5aR) expression in trophoblasts of pre‐eclamptic placentas. Further study showed that C5a stimulated trophoblasts towards an anti‐angiogenic phenotype by mediating the imbalance of angiogenic factors such as soluble fms‐like tyrosine kinase 1 (sFlt1) and placental growth factor (PIGF). Additionally, C5a inhibited the migration and tube formation of trophoblasts, while, C5aR knockdown with siRNA rescued migration and tube formation abilities. We also found that maternal C5a serum level was increased in women with PE and was positively correlated with maternal blood pressure and arterial stiffness. These results demonstrated that the placental C5a/C5aR pathway contributed to the development of PE by regulating placental trophoblasts dysfunctions, suggesting that C5a may be a novel therapeutic possibility for the disease.

Longitudinal assessment of HLA and MIC-A antibodies in uneventful pregnancies and pregnancies complicated by preeclampsia or gestational diabetes

The significance of antibodies directed against paternal epitopes in the context of obstetric disorders is discussed controversially. In this study anti-HLA and anti-MIC-A antibodies were analysed in sera of women with uneventful pregnancy (n = 101), preeclampsia (PE, n = 55) and gestational diabetes (GDM, n = 36) using antigen specific microbeads. While two thirds of the women with uneventful pregnancy or GDM were HLA and MIC-A antibody positive in gestational week 11 to 13 with a modest increase towards the end of pregnancy, women with PE showed an inverse kinetic: 90% were HLA antibody positive in gestational week 11 to 13 and only 10% showed HLA reactivities at the end of the pregnancy. HLA antibody binding strength was more pronounced in gestational week 14 to 17 in patients with PE compared to women with uneventful pregnancy (maximum median fluorescence intensity of the highest ranked positive bead 7403, IQR 2193–7938 vs. 1093, IQR 395–5689; p = 0.04) and was able to predict PE with an AUC of 0.80 (95% CI 0.67–0.93; p = 0.002). Our data suggest a pathophysiological involvement of HLA antibodies in PE. HLA antibody quantification in early pregnancy may provide a useful tool to increase diagnostic awareness in women prone to develop PE.

Cadmium Handling, Toxicity and Molecular Targets Involved during Pregnancy: Lessons from Experimental Models

Even decades after the discovery of Cadmium (Cd) toxicity, research on this heavy metal is still a hot topic in scientific literature: as we wrote this review, more than 1440 scientific articles had been published and listed by the PubMed.gov website during 2017. Cadmium is one of the most common and harmful heavy metals present in our environment. Since pregnancy is a very particular physiological condition that could impact and modify essential pathways involved in the handling of Cd, the prenatal life is a critical stage for exposure to this non-essential element. To give the reader an overview of the possible mechanisms involved in the multiple organ toxic effects in fetuses after the exposure to Cd during pregnancy, we decided to compile some of the most relevant experimental studies performed in experimental models and to summarize the advances in this field such as the Cd distribution and the factors that could alter it (diet, binding-proteins and membrane transporters), the Cd-induced toxicity in dams (preeclampsia, fertility, kidney injury, alteration in essential element homeostasis and bone mineralization), in placenta and in fetus (teratogenicity, central nervous system, liver and kidney).

Longitudinal characterization of renal proximal tubular markers in normotensive and preeclamptic pregnancies

Glomerular damage is common in preeclampsia (PE), but the extent and etiology of tubular injury are not well understood. The aim of this study was to evaluate tubular injury in patients with PE and to assess whether it predates clinical disease. We performed a prospective cohort study of 315 pregnant women who provided urine samples at the end of the second trimester and at delivery. This analysis included women who developed PE ( n = 15), gestational hypertension (GH; n = 14), and normotensive controls (NC; n = 44). Urinary markers of tubular injury, α1-microglobulin (A1M), retinol-binding protein (RBP), kidney-injury molecule-1 (KIM1), complement C5b-9, tissue inhibitor metalloproteinase-2 (TIMP-2), and insulin-like growth factor binding protein-7 (IGFBP-7) were measured by enzyme-linked immunosorbent assay (ELISA) and reported in relation to urine creatinine concentration. Second-trimester concentrations of all markers were similar among groups. At delivery, A1M concentrations were higher in the PE group than in the GH and NC groups as an A1M/creatinine ratio >13 (66.7, 8.3, and 35%, respectively, P = 0.01). Concentrations of C5b-9 were higher in the PE group than in the GH and NC groups (medians 9.85, 0.05, and 0.28 ng/mg, respectively, P = 0.003). KIM1, RBP, TIMP-2, and IGFBP-7 concentrations did not differ among groups at delivery. In conclusion, proximal tubular dysfunction, as assessed by A1M and C5b-9, developed during the interval between the end of the second trimester and delivery in patients with PE. However, this was not matched by abnormalities in markers previously associated with tubular cell injury (KIM-1, IGFBP-7, and TIMP-2).

Estrogens regulate glycosylation of IgG in women and men

The immunologic potency of IgG is modulated by glycosylation, but mechanisms regulating this process are undefined. A role for sex hormones is suggested by differences in IgG glycans between women and men, most prominently with respect to galactose. We therefore assessed IgG galactosylation in 713 healthy adults from 2 cohorts as well as in 159 subjects from 4 randomized controlled studies of endocrine manipulation: postmenopausal women receiving conjugated estrogens, raloxifene, or placebo; premenopausal women deprived of gonadal hormones with leuprolide and treated with estradiol or placebo; men deprived of gonadal hormones with goserelin and given testosterone or placebo; and men deprived of gonadal hormones with goserelin and given testosterone or placebo together with anastrozole to block conversion of testosterone to estradiol. Menopause was associated with an increase in agalactosylated IgG glycans, particularly in the most abundant fucosylated nonbisected (G0F) glycoform. Conjugated estrogens and raloxifene reduced G0F glycans in postmenopausal women, while in premenopausal women leuprolide increased G0F glycans in a manner reversed by estradiol. Among men, goserelin increased G0F glycans, an effect blocked by testosterone through conversion to estradiol. These results establish estrogens as an in vivo modulator of IgG galactosylation in both women and men, defining a pathway by which sex modulates immunity.

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.

Serum C3 and uterine artery Doppler indices at 14-20 weeks gestation for preeclampsia screening in low-risk primigravidas: A prospective observational study

PROBLEM

Preeclampsia affects 2-10% of human pregnancies with poor screening tests. In order to intervene preventively, high risk population should be identified before the 20th week of pregnancy and by a method not subjected to operator efficiency.

METHODOLOGY

Prospective observational study recruiting 825 low risk primigravidas. Serum C3 and uterine artery Doppler indices were measured at 14-20 weeks.

RESULTS

Serum C3 levels at 14-20 weeks of gestation had a sensitivity 83.3%, specificity 100%, PPV 100% and NPV 98.3% when the cut-off value was 53.1mg/. For the mean RI, the best cut off value found was 0.72 with 100% sensitivity, 99.1% specificity, 92.3% PPV and 100% NPV. For the mean PI the best cut off value was 1.35 with 100% sensitivity, 94.1% specificity, 63.2% PPV and 100% NPV. The combination of serum C3 level and mean uterine artery PI showed 100% sensitivity, 97.4% specificity, 80% PPV and 100% NPV in prediction of PE.

CONCLUSION

Serum C3 levels at 14-20 weeks can be used for prediction of PE with comparable results to uterine artery Doppler indices but has the superiority of being operator independent.

Activation of CD35 and CD55 in HIV associated normal and pre-eclamptic pregnant women

OBJECTIVE

The delicate balance which exists between complement activation and its regulation is altered in HIV infection and pregnancy disorders such as pre-eclampsia. Therefore, the purpose of this study was to investigate the expression of complement regulatory (Creg) proteins (CD35 and CD55) in HIV associated normal and pre-eclamptic pregnancies.

STUDY DESIGN

The total study population (n=100) consisted of normotensive pregnant (n=50) and pre-eclamptic (n=50) women. These groups were equally sub-stratified into HIV infected and uninfected groups (n=25 per group). Standard haematological tests were conducted. Flow cytometric analysis of isolated neutrophils were performed using fluorescein isothiocyanate-conjugated anti-CD35 and phycoerythrin-cyanine 5 conjugated anti-CD55.

RESULTS

HELLP syndrome characteristics of increased lactate dehydrogenase enzymes levels, low platelet counts, cell morphological abnormalities (red cell fragmentation) and anaemia were observed in 40% of the HIV infected pre-eclamptic group. Red cell fragmentation inclusive of burr cells and schistocytes were also noted. Activated partial thromboplastin time and fibrinogen differed significantly between the HIV uninfected pre-eclamptic compared to the HIV infected pre-eclamptic groups (p<0.01). Irrespective of HIV status, the mean fluorescence intensity of CD35 and CD55 were significantly higher in the pre-eclamptic compared to the normotensive pregnant (p=0.0001; p=0.0001 respectively) groups. In the pre-eclamptic groups, the expression of both CD35 and CD55 did not significantly differ between HIV infected and uninfected women (p=0.486; p=0.767 respectively).

CONCLUSIONS

This study demonstrates an up-regulation of complement regulatory proteins, CD35 and CD55 in HIV associated pre-eclamptic compared to normotensive pregnancy. This elevation of the Creg proteins is an adaptive immune response to the high complement-mediated cell lysis that occurs in HIV infection and further aggravated by the complement activated state of pre-eclampsia.

The Salivary Scavenger and Agglutinin (SALSA) in Healthy and Complicated Pregnancy

Pre-eclampsia is a leading cause of maternal and perinatal morbidity and mortality worldwide. The etiology is not clear, but an immune attack towards components of placenta or fetus has been indicated. This involves activation of the complement system in the placenta. We have previously described the presence of the complement-regulating protein salivary scavenger and agglutinin (SALSA) in amniotic fluid. In this study we investigated the potential role of SALSA in pregnancy by analyzing its presence in amniotic fluid and placental tissue during healthy and complicated pregnancies. SALSA levels in amniotic fluid increased during pregnancy. Before 20 weeks of gestation the levels were slightly higher in patients who later developed pre-eclampsia than in gestation age-matched controls. In the placenta of pre-eclamptic patients syncytial damage is often followed by the formation of fibrinoid structures. SALSA was found clustered into these fibrinoid structures in partial co-localization with complement C1q and fibronectin. In vitro analysis showed direct protein binding of SALSA to fibronectin. SALSA binds also to fibrin/fibrinogen but did not interfere with the blood clotting process in vitro. Thus, in addition to antimicrobial defense and epithelial differentiation, the data presented here suggest that SALSA, together with fibronectin and C1q, may be involved in the containment of injured placental structures into fibrinoids.

Maternal plasma levels of complement Factor H in miscarriage and in normal pregnancy: A cohort study

The incidence of clinically recognizable miscarriage in general population is up to 15%. It has been shown that complement Factor H (CFH) mRNA levels were increased in endometrium of women during early pregnancy, compared to non-pregnant women. We hypothesized that patients with miscarriage could have lower protein levels of CFH. The objectives of this prospective cohort is to measure plasma levels of Factor H in pregnancies up to 20 weeks, and to investigated whether there is an association between CFH and miscarriage. Plasma levels of CFH were measured in a cohort of pregnant women, ranging from 3 to 19.6 weeks who attended a gynecologic emergency unit in Brazil. Subjects had a blood sample obtained at the first consultation and were followed up to 24 weeks. After reaching outcome, subjects were divided into 4 groups: (1) miscarriage at entry the study, (2) normal pregnancy, (3) those that evolved to miscarriage, and (4) a control group of 6 non-pregnant, fertile proven women. Kruskal-Wallis test was used for statistical analysis. From 193 eligible women, 4 were excluded due technical problems and 33 were lost to follow-up. Median levels (range) of CFH were 989.2 μg/mL (372-1644) n=64; 1042 μg/mL (600.7-1915) n=74; 1089 μg/mL (813.7-1250) n=12; 1004 μg/mL (901.7-1335) n=6 in groups 1-3 and control, respectively; p=0.46-Kruskal-Wallis; post-hoc power (1-β)=31.6%. Therefore, median plasma levels of CFH are not different between women with miscarriage or normal pregnancy up to 19.6 weeks.

Complement Activation in Placental Malaria

Sixty percent of all pregnancies worldwide occur in malaria endemic regions. Pregnant women are at greater risk of malaria infection than their non-pregnant counterparts and have a higher risk of adverse birth outcomes including low birth weight resulting from intrauterine growth restriction and/or preterm birth. The complement system plays an essential role in placental and fetal development as well as the host innate immune response to malaria infection. Excessive or dysregulated complement activation has been associated with the pathobiology of severe malaria and with poor pregnancy outcomes, dependent and independent of infection. Here we review the role of complement in malaria and pregnancy and discuss its part in mediating altered placental angiogenesis, malaria-induced adverse birth outcomes, and disruptions to the in utero environment with possible consequences on fetal neurodevelopment. A detailed understanding of the mechanisms underlying adverse birth outcomes, and the impact of maternal malaria infection on fetal neurodevelopment, may lead to biomarkers to identify at-risk pregnancies and novel therapeutic interventions to prevent these complications.

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.

Complement Split Products C3a/C5a and Receptors: Are They Regulated by Circulating Angiotensin II Type 1 Receptor Autoantibody in Severe Preeclampsia?

BACKGROUND

This study measured the serum levels of complement component (C)3a and C5a and the placental expressions of C3a receptor (R) and C5aR to determine a potential correlation with circulating angiotensin II type 1 (AT1) receptor agonistic autoantibody (AT1-AA) in severe pre-eclampsia.

METHODS

A total of 118 women were recruited and divided into 2 groups: the control group (normotensive preterm pregnancies, n = 66) and severe pre-eclampsia group (n = 52). Levels of C3a, C5a and AT1-AA in serum were measured by enzyme-linked immunosorbent assay and C3aR and C5aR in placenta by Western blotting.

RESULTS

Levels of C3a, C5a and AT1-AA in serum from the severe pre-eclampsia group were significantly higher than in controls (p < 0.05). Placental expression of C3aR and C5aR in the pre-eclampsia group was lower than that in controls (p < 0.05). There were significant positive correlations between levels of C3a, C5a and AT1-AA in serum from the pre-eclampsia group (p < 0.05). In contrast, there was no correlation between C3aR and C5aR in the placenta and AT1-AA in serum in the pre-eclampsia group (p > 0.05).

CONCLUSION

Increased C3a, C5a and AT1-AA in the serum provide indirect evidence that AT1-AA-mediated activation contributes to activate complement, which is a key mechanism underlying the pathogenesis of severe pre-eclampsia.

Complement Split Products in Amniotic Fluid in Pregnancies Subsequently Developing Early-Onset Preeclampsia

Objective. To determine the second-trimester amniotic fluid concentrations of complement split products in pregnancies subsequently affected by early-onset preeclampsia. Study Design. Cohort of 731 women with singleton pregnancies undergoing second-trimester genetic amniocentesis followed up to delivery and analyzed as a nested case-control study. Cases of preeclampsia developing before 34 weeks' gestation (n = 15) were compared with 47 uncomplicated term controls. Amniotic fluid collected at amniocentesis was tested for complement split products Bb, C4a, C3a, and C5a. Results. Women who developed early-onset preeclampsia as compared with the term pregnant controls had significantly higher (P = 0.04) median amniotic fluid C3a levels (318.7 ng/mL versus 254.5 ng/mL). Median amniotic fluid Bb levels were also significantly higher (P = 0.03) in preeclamptic women than in normal pregnant women (1127 ng/mL versus 749 ng/mL). Median levels of C4a and C5a were not significantly different between the groups. Conclusion. Our data suggest that complement activation in early pregnancy is associated with early-onset preeclampsia. We believe this to be the first prospective study to link complement activation in amniotic fluid in early pregnancy and later development of preeclampsia. Our findings provide evidence that immune dysregulation may precede the clinical manifestations of preeclampsia and that the alternative complement pathway is principally involved.

Pre-eclampsia as a manifestation of antiphospholipid syndrome: assessing the current status

The presence of antiphospholipid antibodies is considered a risk factor for pre-eclampsia. Two meta-analyses and a number of case-control and cohort studies have found associations between pre-eclampsia and lupus anticoagulant, anticardiolipin, and/or anti-β2 glycoprotein I. However, existing literature is inconsistent, with varying severity of pre-eclampsia phenotype examined, differing aPL titer cutoffs used to define positive status, and an overwhelming lack of repeat confirmatory aPL testing. This calls into question the link between aPLs and pre-eclampsia, or at least makes it less well defined. There is evidence for a mechanistic pathway between aPLs and adverse pregnancy outcomes (APOs) including pre-eclampsia via the complement pathway. Complement appears to be overactive in pregnancies affected by APOs. A mouse model has show that the fetal wastage caused by treatment with human aPLs can be salvaged by either creating genetic knockouts along the complement, TNF-alpha, and tissue factor pathways or be treating mice with monoclonal antibodies blocking key complement factors. Thus, this is worth further investigation to clarify the likely association of aPLs and pre-eclampsia in humans, as well is to further evaluate the interaction with complement in human pregnancies.

Assessment of angiogenesis modulators in pregnant women with pre-eclampsia: a case-control study

PURPOSE

This study aimed to evaluate the serum concentration of factors associated with placental angiogenesis in pre-eclamptic and normotensive pregnant women.

METHODS

This was a prospective, cross-sectional, case-control study in which the pro-angiogenic factors PlGF, VEGF and IL-10, and the anti-angiogenic factors IL-6, IL-17 and TNF-α of 55 pregnant women (31 with pre-eclampsia-PE and 24 normotensive), with gestational age ≥20 weeks, were measured in maternal blood through the enzyme-linked immunosorbent assay (ELISA). The Mann-Whitney and Kruskal-Wallis tests were used for comparison between groups.

RESULTS

Serum PIGF was reduced in the group of pregnant women with PE when compared with the normotensive women (493.2 ± 55.1 pg/mL vs. 4.4 ± 26.5 pg/mL; p < 0.001). There was no significant difference in PlGF levels in the pre-eclamptic pregnant women in relation to gestational age or proteinuria levels (p > 0.05). The serum levels of VEGF, IL-17, IL-10 and TNF-α were lower in the pregnant women with PE when compared with their normotensive peers, while the IL-6 levels were higher; however, this difference was not statistically significant (p > 0.05).

CONCLUSION

Serum PlGF levels were reduced in the pregnant women with PE and were unrelated to disease severity. Serum levels of VEGF, IL-17, IL-10 and TNF-α were reduced in the pre-eclamptic pregnant women when compared with their normotensive peers, without statistically significant differences.

Prevention of Defective Placentation and Pregnancy Loss by Blocking Innate Immune Pathways in a Syngeneic Model of Placental Insufficiency

Defective placentation and subsequent placental insufficiency lead to maternal and fetal adverse pregnancy outcome, but their pathologic mechanisms are unclear, and treatment remains elusive. The mildly hypertensive BPH/5 mouse recapitulates many features of human adverse pregnancy outcome, with pregnancies characterized by fetal loss, growth restriction, abnormal placental development, and defects in maternal decidual arteries. Using this model, we show that recruitment of neutrophils triggered by complement activation at the maternal/fetal interface leads to elevation in local TNF-α levels, reduction of the essential angiogenic factor vascular endothelial growth factor, and, ultimately, abnormal placentation and fetal death. Blockade of complement with inhibitors specifically targeted to sites of complement activation, depletion of neutrophils, or blockade of TNF-α improves spiral artery remodeling and rescues pregnancies. These data underscore the importance of innate immune system activation in the pathogenesis of placental insufficiency and identify novel methods for treatment of pregnancy loss mediated by abnormal placentation.

Biomarker development for presymptomatic molecular diagnosis of preeclampsia: feasible, useful or even unnecessary?

The past decade saw the advent of a number of promising biomarkers to detect pregnancies at risk for preeclampsia (PE), the foremost being those associated with an imbalance of angiogenic factors. In late pregnancy, these are useful for the detection of imminent cases of PE, while earlier they were more predictive for early- than late-onset PE. This suggests that there may be fundamental differences between the underlying pathology of these two PE forms. Therefore, it is possible that such a biological premise may limit the development of biomarkers that will permit the efficacious detection of both early- and late-onset PE via an analysis of first-trimester maternal blood samples. Consequently, a significant increase in our understanding of the underlying pathology of PE, using a variety of approaches ranging from systems biology to animal models, will be necessary in order to overcome this obstacle.

Preeclampsia - will orphan drug status facilitate innovative biological therapies?

It is generally accepted that the development of novel therapies to treat pregnancy-related disorders, such as preeclampsia, is hampered by the paucity of research funding. Hence, it is with great interest to become aware of at least three novel therapeutic approaches for the treatment of this disorder: exploiting either the anticoagulant activity of antithrombin, the free radical scavenging activity of alpha-1-microglobulin, or the regenerative capacity of placenta-derived mesenchymal stem cells. As these projects are being carried out by small biotech enterprises, the question arises of how they are able to fund such undertakings. A novel strategy adopted by two of these companies is that they successfully petitioned US and EU agencies in order that preeclampsia is accepted in the register of rare or orphan diseases. This provides a number of benefits including market exclusivity, assistance with clinical trials, and dedicated funding schemes. Other strategies to supplement meager research funds, especially to test novel approaches, could be crowdfunding, a venture that relies on intimate interaction with advocacy groups. In other words, preeclampsia meets Facebook. Perhaps similar strategies can be adopted to examine novel therapies targeting either the imbalance in pro- or anti-angiogenic growth factors, complement activation, reduced levels of placenta protein 13, or excessive neutrophil activation evident in preeclampsia.