Circulating soluble endoglin levels in pregnant women in Cameroon and Malawi--associations with placental malaria and fetal growth restriction

Association of mid-trimester maternal angiogenic biomarkers with small-for-gestational-age infants in an urban Zambian cohort: a nested case-control study

Objective

To investigate whether angiogenic biomarker concentrations differ between women who deliver small‐for‐gestational‐age (SGA) infants (<10th centile birth weight for gestational age) compared with controls, because identifying SGA risk early could improve outcomes.

Methods

This case‐control study compared serum concentrations of angiogenic biomarkers before 24 weeks of pregnancy from 62 women who delivered SGA infants (cases) and 62 control women from an urban Zambian cohort. Odds of delivering an SGA infant were calculated using conditional logistic regression.

Results

Placental growth factor (PlGF), soluble fms‐like tyrosine kinase (sFLT‐1) and soluble endoglin (sEng) in controls were 37.74 pg/mL (interquartile range [IQR] 23.12–63.15), 2525.18 pg/mL (IQR 1502.21–4265.54) and 2408.18 pg/mL (IQR 1854.87–3017.94), respectively. SGA cases had higher PlGF (40.50 pg/mL, IQR 22.81–67.94) and sFLT‐1 (2613.06 pg/mL, IQR 1720.58–3722.50), and lower sEng (2038.06 pg/mL, IQR 1445.25–3372.26). Participants with sEng concentration below and concomitant sFLT‐1 concentration above their respective thresholds (n = 40) had five‐fold higher odds of SGA (adjusted odds ratio 4.77, 95% confidence interval 1.61–14.1; P = 0.005).

Conclusion

Biomarker concentrations were similar between cases and controls. Participants with concomitant low sEng and high sFLT‐1 had the highest odds of SGA, suggesting that a combination of biomarkers may better for predicting SGA than single biomarkers.

Prediction of SGA risk using the interaction of multiple angiogenic biomarkers may perform better than using a single angiogenic biomarker concentration before 24 weeks gestation.

Falciparum but not vivax malaria increases the risk of hypertensive disorders of pregnancy in women followed prospectively from the first trimester

BACKGROUND

Malaria and hypertensive disorders of pregnancy (HDoP) affect millions of pregnancies worldwide, particularly those of young, first-time mothers. Small case-control studies suggest a positive association between falciparum malaria and risk of pre-eclampsia but large prospective analyses are lacking.

METHODS

We characterized the relationship between malaria in pregnancy and the development of HDoP in a large, prospectively followed cohort. Pregnant women living along the Thailand-Myanmar border, an area of low seasonal malaria transmission, were followed at antenatal clinics between 1986 and 2016. The relationships between falciparum and vivax malaria during pregnancy and the odds of gestational hypertension, pre-eclampsia, or eclampsia were examined using logistic regression amongst all women and then stratified by gravidity.

RESULTS

There were 23,262 singleton pregnancies in women who presented during the first trimester and were followed fortnightly. Falciparum malaria was associated with gestational hypertension amongst multigravidae (adjusted odds ratio (AOR) 2.59, 95%CI 1.59-4.23), whereas amongst primigravidae, it was associated with the combined outcome of pre-eclampsia/eclampsia (AOR 2.61, 95%CI 1.01-6.79). In contrast, there was no association between vivax malaria and HDoP.

CONCLUSIONS

Falciparum but not vivax malaria during pregnancy is associated with hypertensive disorders of pregnancy.

VAR2CSA-Mediated Host Defense Evasion of Plasmodium falciparum Infected Erythrocytes in Placental Malaria

Over 30 million women living in P. falciparum endemic areas are at risk of developing malaria during pregnancy every year. Placental malaria is characterized by massive accumulation of infected erythrocytes in the intervillous space of the placenta, accompanied by infiltration of immune cells, particularly monocytes. The consequent local inflammation and the obstruction of the maternofetal exchanges can lead to severe clinical outcomes for both mother and child. Even if protection against the disease can gradually be acquired following successive pregnancies, the malaria parasite has developed a large panel of evasion mechanisms to escape from host defense mechanisms and manipulate the immune system to its advantage. Infected erythrocytes isolated from placentas of women suffering from placental malaria present a unique phenotype and express the pregnancy-specific variant VAR2CSA of the Plasmodium falciparum Erythrocyte Membrane Protein (PfEMP1) family at their surface. The polymorphic VAR2CSA protein is able to mediate the interaction of infected erythrocytes with a variety of host cells including placental syncytiotrophoblasts and leukocytes but also with components of the immune system such as non-specific IgM. This review summarizes the described VAR2CSA-mediated host defense evasion mechanisms employed by the parasite during placental malaria to ensure its survival and persistence.

Effects of Malaria in the First Trimester of Pregnancy on Poor Maternal and Birth Outcomes in Benin

BACKGROUND

In sub-Saharan Africa, malaria in the first half of pregnancy is harmful for both the mother and her fetus. However, malaria in the first trimester of pregnancy, when women are usually not protected against malaria, has been little investigated. For the first time, we assessed the effects of malaria in the first trimester on maternal and birth outcomes using a preconceptional study design.

METHODS

From June 2014 to March 2017, 1214 women of reproductive age were recruited and followed monthly until 411 became pregnant. The pregnant women were then followed from 5-6 weeks of gestation until delivery. Path analysis was used to assess the direct effect (ie, not mediated by malaria in the second or third trimester) of malaria in the first trimester on maternal anemia and poor birth outcomes. The cumulative effect of infections during pregnancy on the same outcomes was also evaluated.

RESULTS

The prevalence of malaria infections in the first trimester was 21.8%. Malaria in the first trimester was significantly associated with maternal anemia in the third trimester (adjusted odds ratio 2.25, 95% confidence interval 1.11-4.55). While we did not find evidence of any direct effect of first trimester malaria infections on birth outcomes, their association with infections later in pregnancy tended to increase the risk of low birth weights.

CONCLUSIONS

Malaria infections in the first trimester were highly prevalent and have deleterious effects on maternal anemia. They highlight the need for additional preventive measures, starting in early pregnancy or even before conception.

Association of Angiopoietin Dysregulation in Placental Malaria with Adverse Birth Outcomes

Malaria in pregnancy causes adverse birth outcomes due to sequestration of Plasmodium falciparum-infected erythrocytes in the placenta. Angiopoietins are critical regulators of vascular development and formation of placental villous vasculature. Angiopoietin-1 and Angiopoietin-2 concentrations were measured in peripheral and placental plasma samples from 70 malaria-infected and 216 control women using commercially available DuoSet ELISA development kit. Angiopoietins increased in placental plasma (ANG1-5833.5 pg/ml and ANG2-9580.6 pg/ml) as compared to peripheral plasma (ANG1-2293.1 pg/ml and ANG2-1198.9 pg/ml, p < 0.0001). The concentration of placental and peripheral ANG1 (6099.23 pg/ml and 2320.5 pg/ml) was significantly lower (5013.5 pg/ml, 2208.5 pg/ml), and ANG2 (9553.3 pg/ml, 1180.92 pg/ml) was significantly higher (9664.6 pg/ml, 1254.4 pg/ml) in malaria-positive cases as compared to malaria-negative (p < 0.0001). The association of dysregulated angiopoietins in malaria with adverse birth outcomes showed that the peripheral and placental ANG1 concentration was lower and ANG2 concentration was higher in low-birth-weight baby and stillbirth birth outcome as compared to normal deliveries among malaria-positive group. Therefore, ANG1 and ANG2 could be considered a biomarker for adverse outcome during malaria in pregnancy.

Early malaria infection, dysregulation of angiogenesis, metabolism and inflammation across pregnancy, and risk of preterm birth in Malawi: A cohort study

BACKGROUND

Malaria in pregnancy is associated with adverse birth outcomes. However, the underlying mechanisms remain poorly understood. Tight regulation of angiogenic, metabolic, and inflammatory pathways are essential for healthy pregnancies. We hypothesized that malaria disrupts these pathways leading to preterm birth (PTB).

METHODS AND FINDINGS

We conducted a secondary analysis of a randomized trial of malaria prevention in pregnancy conducted in Malawi from July 21, 2011, to March 18, 2013. We longitudinally assessed circulating mediators of angiogenic, metabolic, and inflammatory pathways during pregnancy in a cohort of HIV-negative women (n = 1,628), with a median age of 21 years [18, 25], and 562 (35%) were primigravid. Pregnancies were ultrasound dated, and samples were analyzed at 13 to 23 weeks (Visit 1), 28 to 33 weeks (Visit 2), and/or 34 to 36 weeks (Visit 3). Malaria prevalence was high; 70% (n = 1,138) had PCR-positive Plasmodium falciparum infection at least once over the course of pregnancy and/or positive placental histology. The risk of delivering preterm in the entire cohort was 20% (n = 304/1506). Women with malaria before 24 weeks gestation had a higher risk of PTB (24% versus 18%, p = 0.005; adjusted relative risk [aRR] 1.30, 95% confidence interval [CI] 1.04-1.63, p = 0.021); and those who were malaria positive only before week 24 had an even greater risk of PTB (28% versus 17%, p = 0.02; with an aRR of 1.67, 95% CI 1.20-2.30, p = 0.002). Using linear mixed-effects modeling, malaria before 24 weeks gestation was associated with altered kinetics of inflammatory (C-Reactive Protein [CRP], Chitinase 3-like protein-1 [CHI3L1], Interleukin 18 Binding Protein [IL-18BP], soluble Tumor Necrosis Factor receptor II [sTNFRII], soluble Intercellular Adhesion Molecule-1 [sICAM-1]), angiogenic (soluble Endoglin [sEng]), and metabolic mediators (Leptin, Angiopoietin-like 3 [Angptl3]) over the course of pregnancy (χ2 > 13.0, p ≤ 0.001 for each). Limitations include being underpowered to assess the impact on nonviable births, being unable to assess women who had not received any antimalarials, and, because of the exposure to antimalarials in the second trimester, there were limited numbers of malaria infections late in pregnancy.

CONCLUSIONS

Current interventions for the prevention of malaria in pregnancy are initiated at the first antenatal visit, usually in the second trimester. In this study, we found that many women are already malaria-infected by their first visit. Malaria infection before 24 weeks gestation was associated with dysregulation of essential regulators of angiogenesis, metabolism, and inflammation and an increased risk of PTB. Preventing malaria earlier in pregnancy may reduce placental dysfunction and thereby improve birth outcomes in malaria-endemic settings.

The Impact of Infection in Pregnancy on Placental Vascular Development and Adverse Birth Outcomes

Healthy fetal development is dependent on nutrient and oxygen transfer via the placenta. Optimal growth and function of placental vasculature is therefore essential to support in utero development. Vasculogenesis, the de novo formation of blood vessels, and angiogenesis, the branching and remodeling of existing vasculature, mediate the development and maturation of placental villi, which form the materno-fetal interface. Several lines of evidence indicate that systemic maternal infection and consequent inflammation can disrupt placental vasculogenesis and angiogenesis. The resulting alterations in placental hemodynamics impact fetal growth and contribute to poor birth outcomes including preterm delivery, small-for-gestational age (SGA), stillbirth, and low birth weight (LBW). Furthermore, pathways involved in maternal immune activation and placental vascularization parallel those involved in normal fetal development, notably neurovascular development. Therefore, immune-mediated disruption of angiogenic pathways at the materno-fetal interface may also have long-term neurological consequences for offspring. Here, we review current literature evaluating the influence of maternal infection and immune activation at the materno-fetal interface and the subsequent impact on placental vascular function and birth outcome. Immunomodulatory pathways, including chemokines and cytokines released in response to maternal infection, interact closely with the principal pathways regulating placental vascular development, including the angiopoietin-Tie-2, vascular endothelial growth factor (VEGF), and placental growth factor (PlGF) pathways. A detailed mechanistic understanding of how maternal infections impact placental and fetal development is critical to the design of effective interventions to promote placental growth and function and thereby reduce adverse birth outcomes.

Prevalence and Associated Risk Factors of Malaria in the First Trimester of Pregnancy: A Preconceptional Cohort Study in Benin

Background

There is a lack of data on the burden of malaria in the first trimester of pregnancy in Africa, mainly because pregnant women generally attend the maternity clinic late. Bed nets are rarely provided to women before the second trimester of pregnancy and intermittent preventive treatment with sulfadoxine-pyrimethamine is not recommended before the second trimester, leaving women insufficiently or not protected in early pregnancy.

Methods

To assess the burden of first trimester malaria, 387 women were followed up monthly from preconception to delivery. They were screened for malaria monthly from early pregnancy until delivery. A logistic multilevel model was used to assess maternal factors associated with malaria during the first trimester.

Results

The proportion of women with at least 1 microscopic malaria infection during the first trimester of pregnancy was 20.8%. Women infected with malaria preconception were more likely to be infected during the first trimester (adjusted odds ratio: 2.68; 95% confidence interval, 1.24-5.78). Early gestational age was also positively correlated with malaria infection.

Conclusions

Using a preconceptional study design, we showed that malaria was highly prevalent in early pregnancy. This calls for the assessment of new strategies that could protect women as soon as the first trimester.

Molecular Principles of Intrauterine Growth Restriction in Plasmodium Falciparum Infection

Malaria in pregnancy still constitutes a particular medical challenge in tropical and subtropical regions. Of the five Plasmodium species that are pathogenic to humans, infection with Plasmodium falciparum leads to fulminant progression of the disease with massive impact on pregnancy. Severe anemia of the mother, miscarriage, stillbirth, preterm delivery and intrauterine growth restriction (IUGR) with reduced birth weight are frequent complications that lead to more than 10,000 maternal and 200,000 perinatal deaths annually in sub-Saharan Africa alone. P. falciparum can adhere to the placenta via the expression of the surface antigen VAR2CSA, which leads to sequestration of infected erythrocytes in the intervillous space. This process induces a placental inflammation with involvement of immune cells and humoral factors. Especially, monocytes get activated and change the release of soluble mediators, including a variety of cytokines. This proinflammatory environment contributes to disorders of angiogenesis, blood flow, autophagy, and nutrient transport in the placenta and erythropoiesis. Collectively, they impair placental functions and, consequently, fetal growth. The discovery that women in endemic regions develop a certain immunity against VAR2CSA-expressing parasites with increasing number of pregnancies has redefined the understanding of malaria in pregnancy and offers strategies for the development of vaccines. The following review gives an overview of molecular processes in P. falciparum infection in pregnancy which may be involved in the development of IUGR.

Bradykinin Sequestration by Plasmodium berghei Infected Erythrocytes Conditions B2R Signaling and Parasite Uptake by Fetal Trophoblasts

Plasmodium infection during pregnancy causes placental malfunction reducing fetus sustainability and leading to abortions, stillbirths, low birth weight or premature delivery. Accumulation of infected erythrocytes (IE) in the placenta is a key factor in placental malaria pathogenesis but the role played by fetal trophoblast that contact maternal blood has been neglected. Here we explore the hypothesis that interactions between Plasmodium-IE and fetal trophoblast cells impact on vasoactive alterations underlying placental dysfunction. We screened gene expression of key mediators in vasoactive pathways. We found that mRNA of bradykinin receptor 2 (B2R) and nitric oxide synthase (eNOS), as well as levels of bradykinin (BK), were decreased in late gestation placentas of pregnant Plasmodium berghei-infected mice. Co-culturing mouse trophoblasts with IE down-regulated B2R transcription and interleukin (IL)-6 secretion in a B2R-signaling dependent manner. IE showed increased levels of surface B2R and enhanced capacity to bind BK. We propose that down-regulation of B2R signaling in the course of IE–trophoblast interactions is due to BK sequestration by IE. In corroboration, levels of BK were lower in infected placentas and the positive correlation of B2R gene expression and fetal weight was disrupted by infection. This indicates that deregulation of the BK-B2R pathway is associated to placental dysfunction provoked by malaria infection. We further found that upon inhibition of B2R signaling, trophoblasts engulf IE to a lesser extent and show reduced production of IL-6. Our data suggest that BK sequestration by P. berghei represents a strategy for the parasite to ameliorate the risk of phagocytic capture by down modulating B2R activation.

Association of Antibodies to VAR2CSA and Merozoite Antigens with Pregnancy Outcomes in Women Living in Yaoundé, Cameroon

Plasmodium falciparum infections are serious in pregnant women, because VAR2CSA allows parasitized erythrocytes to sequester in the placenta, causing placental malaria (PM). In areas of endemicity, women have substantial malarial immunity prior to pregnancy, including antibodies to merozoite antigens, but produce antibodies to VAR2CSA only during pregnancy. The current study sought to determine the importance of antibodies to VAR2CSA and merozoite antigens in pregnant women in Yaoundé, Cameroon, where malaria transmission was relatively low. A total of 1,377 archival plasma samples collected at delivery were selected (at a 1:3 ratio of PM-positive [PM+] to PM-negative [PM-] women) and screened for antibodies to full-length VAR2CSA and 7 merozoite antigens. Results showed that many PM+ women and most PM- women lacked antibodies to VAR2CSA at delivery. Among PM+ women, antibodies to VAR2CSA were associated with a reduced risk of having high placental parasitemia (odds ratio [OR], 0.432; confidence interval [CI], 0.272, 0.687; P = 0.0004) and low-birth-weight (LBW) babies (OR = 0.444; CI, 0.247, 0.799; P = 0.0068), even during first pregnancies. Among antibodies to the 7 merozoite antigens, i.e., AMA1, EBA-175, MSP1₄₂, MSP2, MSP3, MSP11, and Pf41, only antibodies to MSP3, EBA-175, and Pf41 were associated with reduced risk for high placental parasitemias (P = 0.0389, 0.0291, and 0.0211, respectively) and antibodies to EBA-175 were associated with reduced risk of premature deliveries (P = 0.0211). However, after adjusting for multiple comparisons significance declined. Thus, in PM+ women, antibodies to VAR2CSA were associated with lower placental parasitemias and reduced prevalence of LBW babies in this low-transmission setting.

Optimization of BeWo model to investigate placental responses to Plasmodium falciparum infected erythrocytes

Background

Establishment of an in vitro model to study placental malaria is essential for understanding the biology and pathogenesis of placental malaria. We defined experimental variables for obtaining responses of BeWo cells to placental binding Plasmodium falciparum infected erythrocytes (IE, CS2 parasites).

Materials and methods

Experimental variables included i) concentration of forskolin, a cyclic adenosine monophosphate inducer important in the induction of syncytialisation of BeWo, ii) suitable period of incubating BeWo with forskolin, and iii) ratio of IE to BeWo cells and length of incubation to induce physiological changes in BeWo cells, including the vasculogenic factors vascular endothelial growth factor A (VEGFA), endoglin, and angiopoietin-2; an anti-angiogenic factor (inhibin A); a regulator of cell growth, mammalian target of rapamycin (mTOR); a chemokine (IL-8); and the cytokine macrophage inhibition factor. The human hormone, chorionic gonadotrophin was used as a marker for syncytialisation.

Results

We showed that 72 hrs incubation of BeWo with 10 μm forskolin resulted in higher levels of syncytialisation and hCG secretion. Overall, the best condition was to co-culture syncytialised BeWo with a 10:1 ratio of IE for 48 hours. Under these conditions, when co-cultured with IE, BeWo produced increased amounts of IL-8 (p=0.0001), VEGF (p=0.001) and endoglin (p=0.001).

Conclusion

The model can be used to evaluate the impact of IE, inflammatory cytokines and other factors associated with placental malaria on syncytiotrophoblast function.

Usefulness of a biomarker to identify placental dysfunction in the context of malaria

In most tropical areas, pregnant women are at increased risk of malaria, as a consequence of the massive sequestration of parasitized red blood cells in the placenta. The placenta plays a key role in embryonic and fetal development as well as in maternal-fetal exchanges, and pregnancy-associated malaria may alter selected placenta functions that lead to stillbirth and low birth weight. Although there are several tools (blood smear examination, RDT, PCR) to diagnose malaria infection during pregnancy, there is currently no test to assess placenta dysfunction in the framework of pregnancy-associated malaria. Pregnancy-associated malaria shares many features with preeclampsia, an extensively studied disease. Various biomarkers associated with placental dysfunction have been identified as associated with preeclampsia. Several of these are inflammatory markers that lack of specificity. A few seem more specific of placenta dysfunction, including s-endoglin and sFlt1, increased in the peripheral blood during preeclampsia. The predictive value of these biomarkers should be studied in the context of pregnancy-associated malaria to evaluate their usefulness in identifying placental dysfunction during malaria. These biomarkers should be considered to improve the diagnosis of placental dysfunction during malaria and pregnant women monitoring.

Gay Male Only-Children: Evidence for Low Birth Weight and High Maternal Miscarriage Rates

Recent findings suggest that there may be a maternal immune response underpinning the etiology of sexual orientation of gay male only-children. This maternal immune response appears to be distinct from that which is purported to explain the classic fraternal birth order effect found in studies of male sexual orientation. We tested two predictions related to the hypothesized maternal immune response in mothers of gay male only-children: (1) elevated fetal loss among mothers who have had gay male only-children and (2) lower birth weight in gay male only-children. Mothers of at least one gay son (n = 54) and mothers of heterosexual son(s) (n = 72) self-reported their pregnancy histories, including the birth weights of newborns and number of fetal losses (e.g., miscarriages). Mothers of gay male only-children (n = 8) reported significantly greater fetal loss compared with mothers of males with four other sibship compositions (gay with no older brothers, gay with older brothers, heterosexual only-children, heterosexual with siblings) (n = 118). Also, firstborn gay male only-children (n = 4) had a significantly lower birth weight than firstborn children in the four other sibship compositions (n = 59). Duration of pregnancy was not significantly different among the groups of firstborn children in the birth weight analyses. Thus, this study found further support for a distinct pattern of maternal immune response implicated in the etiology of male sexual orientation. Mechanisms that may underlie this potential second type of maternal immune response are discussed.

Urinary tract infection during pregnancy, angiogenic factor profiles, and risk of preeclampsia

BACKGROUND

Despite decades of research, and much progress in discernment of biomarkers in the maternal circulation, the pathogenesis of preeclampsia (PE) remains elusive. The pathophysiology of PE is believed to involve aberrant placentation and an associated increase in systemic inflammation. In this conceptualization, PE becomes more likely when the level of systemic inflammatory burden inherent in pregnancy itself exceeds the maternal capacity to compensate for this additional stress. If this is the case, then it is possible to hypothesize that conditions, such as infectious disease, that increase systemic inflammatory burden should also increase the risk of PE. As urinary tract infection (UTI) represents a common source of inflammation during pregnancy, we tested whether presence of UTI during pregnancy increased the odds of developing PE. Prior work has documented this association. However many of these studies were limited by small cohort sizes and insufficient control for covariates.

OBJECTIVE

The present study is a secondary analysis of a robust contemporary obstetrical cohort recruited to examine the ability of longitudinally sampled maternal angiogenic concentrations to predict PE. We hypothesize that the occurrence of UTI during a pregnancy is associated with the later occurrence of PE in that pregnancy. As PE is believed to be associated with aberrations in systemic angiogenic levels (placental growth factor and soluble isoform of VEGF receptor), we further hypothesize that there will be significant interactions between maternal angiogenic protein levels and the occurrence of UTI.

STUDY DESIGN

Women aged ≥18 years (n = 2607) were recruited and followed up prospectively from the initiation of prenatal care through delivery at 3 regional academic centers. PE was defined by American Congress of Obstetricians and Gynecologists criteria and was independently validated by a panel of physicians. UTI was defined by the presence of clinical symptoms necessitating treatment in addition to supportive laboratory evidence. Multivariate logistic regression models were used and controlled for maternal age, race, parity, body mass index, hypertension, diabetes, in vitro fertilization, and smoking status.

RESULTS

There were 129 women with diagnosed UTIs and 235 with PE. Patients with UTI in pregnancy had higher rates of PE (31.1% vs 7.8%, P < .001) compared to those without reported UTI. The mean gestational age (SD) for UTI diagnosis in PE cases and controls was 25.6 (10.4) and 21.9 (10.9) weeks, respectively (P = .08). The unadjusted odds ratio for PE in the setting of UTI was 5.29 (95% confidence interval, 3.54-7.89). After controlling for confounders, UTI was associated with an odds ratio for PE of 3.2 (95% confidence interval, 2.0-5.1).

CONCLUSION

Presence of UTI in pregnancy, particularly in the third trimester, is strongly associated with PE. This association supports the hypothesis that the risk of PE is enhanced by an increased maternal inflammatory burden. Prophylaxis against UTI represents a potentially low-cost global intervention to slow or halt the development of PE.

A Dormant Microbial Component in the Development of Preeclampsia

Preeclampsia (PE) is a complex, multisystem disorder that remains a leading cause of morbidity and mortality in pregnancy. Four main classes of dysregulation accompany PE and are widely considered to contribute to its severity. These are abnormal trophoblast invasion of the placenta, anti-angiogenic responses, oxidative stress, and inflammation. What is lacking, however, is an explanation of how these themselves are caused. We here develop the unifying idea, and the considerable evidence for it, that the originating cause of PE (and of the four classes of dysregulation) is, in fact, microbial infection, that most such microbes are dormant and hence resist detection by conventional (replication-dependent) microbiology, and that by occasional resuscitation and growth it is they that are responsible for all the observable sequelae, including the continuing, chronic inflammation. In particular, bacterial products such as lipopolysaccharide (LPS), also known as endotoxin, are well known as highly inflammagenic and stimulate an innate (and possibly trained) immune response that exacerbates the inflammation further. The known need of microbes for free iron can explain the iron dysregulation that accompanies PE. We describe the main routes of infection (gut, oral, and urinary tract infection) and the regularly observed presence of microbes in placental and other tissues in PE. Every known proteomic biomarker of "preeclampsia" that we assessed has, in fact, also been shown to be raised in response to infection. An infectious component to PE fulfills the Bradford Hill criteria for ascribing a disease to an environmental cause and suggests a number of treatments, some of which have, in fact, been shown to be successful. PE was classically referred to as endotoxemia or toxemia of pregnancy, and it is ironic that it seems that LPS and other microbial endotoxins really are involved. Overall, the recognition of an infectious component in the etiology of PE mirrors that for ulcers and other diseases that were previously considered to lack one.

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.

Syncytiotrophoblast Functions and Fetal Growth Restriction during Placental Malaria: Updates and Implication for Future Interventions

Syncytiotrophoblast lines the intervillous space of the placenta and plays important roles in fetus growth throughout gestation. However, perturbations at the maternal-fetal interface during placental malaria may possibly alter the physiological functions of syncytiotrophoblast and therefore growth and development of the embryo in utero. An understanding of the influence of placental malaria on syncytiotrophoblast function is paramount in developing novel interventions for the control of placental pathology associated with placental malaria. In this review, we discuss how malaria changes syncytiotrophoblast function as evidenced from human, animal, and in vitro studies and, further, how dysregulation of syncytiotrophoblast function may impact fetal growth in utero. We also formulate a hypothesis, stemming from epidemiological observations, that nutrition may override pathogenesis of placental malaria-associated-fetal growth restriction. We therefore recommend studies on nutrition-based-interventional approaches for high placental malaria-risk women in endemic areas. More investigations on the role of nutrition on placental malaria pathogenesis are needed.

Host biomarkers are associated with progression to dengue haemorrhagic fever: a nested case-control study

OBJECTIVES

Dengue represents the most important arboviral infection worldwide. Onset of circulatory collapse can be unpredictable. Biomarkers that can identify individuals at risk of plasma leakage may facilitate better triage and clinical management.

DESIGN

Using a nested case-control design, we randomly selected subjects from a prospective cohort study of dengue in Colombia (n=1582). Using serum collected within 96 hours of fever onset, we tested 19 biomarkers by ELISA in cases (developed dengue hemorrhagic fever or dengue shock syndrome (DHF/DSS); n=46), and controls (uncomplicated dengue fever (DF); n=65) and healthy controls (HC); n=15.

RESULTS

Ang-1 levels were lower and angptl3, sKDR, sEng, sICAM-1, CRP, CXCL10/IP-10, IL-18 binding protein, CHI3L1, C5a and Factor D levels were increased in dengue compared to HC. sICAM-1, sEng and CXCL10/IP-10 were further elevated in subjects who subsequently developed DHF/DSS (p=0.008, p=0.028 and p=0.025, respectively). In a logistic regression model, age (odds ratio (OR) (95% CI): 0.95 (0.92-0.98), p=0.001), hyperesthesia/hyperalgesia (OR; 3.8 (1.4-10.4), p=0.008) and elevated sICAM-1 (>298ng/mL: OR; 6.3 (1.5-25.7), p=0.011) at presentation were independently associated with progression to DHF/DSS.

CONCLUSIONS

These results suggest that inflammation and endothelial activation are important pathways in the pathogenesis of dengue and sICAM-1 levels may identify individuals at risk of plasma leakage.

Birth weight and two possible types of maternal effects on male sexual orientation: a clinical study of children and adolescents referred to a Gender Identity Service

This study tested predictions regarding two hypothesized maternal immune responses influencing sexual orientation: one affecting homosexual males with high fraternal birth order and another affecting firstborn homosexual individuals whose mothers experience repeated miscarriage after the birth of the first child. Low birth weight was treated as a marker of possible exposure to a maternal immune response during gestation. Birth weight was examined relative to sibship characteristics in a clinical sample of youth (N = 1,722) classified as heterosexual or homosexual based on self-reported or probable sexual orientation. No female sexual orientation differences in birth weight were found. Homosexual, compared to heterosexual, males showed lower birth weight if they had one or more older brothers--and especially two or more older brothers--or if they were an only-child. These findings support the existence of two maternal immune responses influencing male sexual orientation and possibly also cross-gender behavior and identity.

Placental cytokine and chemokine profiles reflect pregnancy outcomes in women exposed to Plasmodium falciparum infection

Pregnancy-associated malaria (PAM) can lead to severe complications for both mother and baby. Certain placental cytokine/chemokine profiles have been shown to reflect poor pregnancy outcomes, including maternal anemia and low birth weight. In intervillous plasma samples from 400 Beninese women living in an area where Plasmodium falciparum is endemic, we quantified 16 cytokines/chemokines. We assessed their profiles in groups with PAM, with maternal anemia, with preterm births, or with a low birth weight for gestational age. Repeated ultrasound measurements ensured that prematurity and low birth weight were highly accurate. Preliminary analyses revealed trends for lower cytokine/chemokine concentrations in placental plasma associated both with babies with low birth weight for gestational age and with P. falciparum infection during pregnancy, while, as a function of the latter, the concentration of gamma interferon (IFN-γ)-inducible protein 10 (IP-10) was higher. Multivariate analyses showed that (i) higher placental plasma interleukin-10 (IL-10) levels were associated with P. falciparum infections and (ii) independently of P. falciparum infections, lower concentrations of both IFN-γ and IL-5 were associated with low birth weight for gestational age. Our data further strengthen the idea that IL-10 and IP-10 could be useful diagnostic markers of P. falciparum infection during pregnancy. The concentrations of cytokines/chemokines in placental plasma may represent previously unrecognized markers of poor fetal growth.

Host biomarkers distinguish dengue from leptospirosis in Colombia: a case-control study

BACKGROUND

Dengue fever and leptospirosis have partially overlapping geographic distributions, similar clinical presentations and potentially life-threatening complications but require different treatments. Distinguishing between these cosmopolitan emerging pathogens represents a diagnostic dilemma of global importance. We hypothesized that perturbations in host biomarkers can differentiate between individuals with dengue fever and leptospirosis during the acute phase of illness.

METHODS

We randomly selected subjects from a prospective cohort study of acute febrile illness in Bucaramanga, Colombia and tested 19 serum biomarkers by ELISA in dengue fever (DF, n = 113) compared to subjects with leptospirosis (n = 47). Biomarkers were selected for further analysis if they had good discriminatory ability (area under the ROC curve (AUC) >0.80) and were beyond a reference range (assessed using local healthy controls).

RESULTS

Nine biomarkers differed significantly between dengue fever and leptospirosis, with higher levels of Angptl3, IL-18BP, IP-10/CXCL10, Platelet Factor 4, sICAM-1, Factor D, sEng and sKDR in dengue and higher levels of sTie-2 in leptospirosis (p < 0.001 for all comparisons). Two biomarkers, sEng and IL18BP, showed excellent discriminatory ability (AUROC >0.90). When incorporated into multivariable models, sEng and IL18BP improved the diagnostic accuracy of clinical information alone.

CONCLUSIONS

These results suggest that host biomarkers may have utility in differentiating between dengue and leptospirosis, clinically similar conditions of different etiology.

Idiopathic urinary findings and fetal growth restriction in low risk pregnancy

OBJECTIVE

To determine whether maternal urinary findings in the first trimester of pregnancy are associated with fetal growth restriction.

STUDY DESIGN

The prevalence of urinary findings in singleton pregnancies complicated by fetal growth restriction were compared with a low-risk control group of pregnancies who gave birth to normal weight babies, in the same condition.

RESULTS

There were significant statistical differences in the mean gestational age (p < 0.001), isolated asymptomatic bacteriuria (p<0.001), hematuria (p = 0.002, OR = 6.6, CI = 1.8-24.2) and proteinuria (p = 0.016, OR = 4.1, CI = 1.2-13.3). There was no recognizable relation between ketonuria and fetal growth restriction.

CONCLUSION

Our data showed a relation between the increase of adverse pregnancy outcomes, including fetal growth restriction, and hematuria, proteinuria and asymptomatic bacteriuria. Appropriate monitoring of pregnant women using these findings may be helpful in the identification of more complications.

Complement activation and the resulting placental vascular insufficiency drives fetal growth restriction associated with placental malaria

Placental malaria (PM) is a major cause of fetal growth restriction, yet the underlying mechanism is unclear. Complement C5a and C5a receptor levels are increased with PM. C5a is implicated in fetal growth restriction in non-infection-based animal models. In a case-control study of 492 pregnant Malawian women, we find that elevated C5a levels are associated with an increased risk of delivering a small-for-gestational-age infant. C5a was significantly increased in PM and was negatively correlated with the angiogenic factor angiopoietin-1 and positively correlated with angiopoietin-2, soluble endoglin, and vascular endothelial growth factor. Genetic or pharmacological blockade of C5a or its receptor in a mouse model of PM resulted in greater fetoplacental vessel development, reduced placental vascular resistance, and improved fetal growth and survival. These data suggest that C5a drives fetal growth restriction in PM through dysregulation of angiogenic factors essential for placental vascular remodeling resulting in placental vascular insufficiency.

Malaria in pregnancy: diagnosing infection and identifying fetal risk

Despite increased malaria control efforts, recent reports indicate that over 1.2 million deaths due to malaria occurred in 2010. Pregnant women represent a particularly vulnerable risk group as malaria infection can lead to life-threatening disease for the mother and fetus. With 125 million women at risk of malaria in pregnancy every year, better diagnostic tools are needed for timely identification and treatment of malaria infection. Diagnostic surveillance tools are also needed to estimate disease burden and inform public health policies. In this review, the authors focus on malaria diagnostics in pregnancy and discuss considerations for different Plasmodium species and geographic regions. The authors also look at promising diagnostic modalities to monitor fetal and maternal health in pregnancy and discuss implementation barriers for low resource settings.

Diagnosing malaria in pregnancy: an update

Pregnancy malaria (PM) due to Plasmodium falciparum is a major cause of morbidity and mortality for women and their offspring, but is difficult to recognize and diagnose. During PM, parasites typically sequester in the placenta, whereas peripheral blood smears often appear negative. In addition, many infected women remain asymptomatic, especially in areas of high transmission where systemic immunity is high, although sequelae including maternal anemia and intrauterine growth retardation develop insidiously and increase mortality. New rapid diagnostic tests (RDTs) have shown promise for malaria diagnosis in nonpregnant individuals, including a product recently approved by the US FDA for use in the USA. However, the sensitivity and specificity of RDTs for diagnosis of PM may be suboptimal. Here, we review the methods that are used to detect or diagnose PM, including blood smear microscopy, RDTs, PCR-based methods, and finally placental histology, which is often cited as the gold standard for use in research studies and clinical trials.

Biomarkers of Plasmodium falciparum infection during pregnancy in women living in northeastern Tanzania

In pregnant women, Plasmodium falciparum infections are an important cause of maternal morbidity as well as fetal and neonatal mortality. Erythrocytes infected by these malaria-causing parasites accumulate through adhesive interactions in placental intervillous spaces, thus evading detection in peripheral blood smears. Sequestered infected erythrocytes induce inflammation, offering the possibility of detecting inflammatory mediators in peripheral blood that could act as biomarkers of placental infection. In a longitudinal, prospective study in Tanzania, we quantified a range of different cytokines, chemokines and angiogenic factors in peripheral plasma samples, taken on multiple sequential occasions during pregnancy up to and including delivery, from P. falciparum-infected women and matched uninfected controls. The results show that during healthy, uninfected pregnancies the levels of most of the panel of molecules we measured were largely unchanged except at delivery. In women with P. falciparum, however, both comparative and longitudinal assessments consistently showed that the levels of IL-10 and IP-10 increased significantly whilst that of RANTES decreased significantly, regardless of gestational age at the time the infection was detected. ROC curve analysis indicated that a combination of increased IL-10 and IP-10 levels and decreased RANTES levels might be predictive of P. falciparum infections. In conclusion, our data suggest that host biomarkers in peripheral blood may represent useful diagnostic markers of P. falciparum infection during pregnancy, but placental histology results would need to be included to verify these findings.