Phenotypic changes of γδ T cells in Plasmodium falciparum placental malaria and pregnancy outcomes in women at delivery in Cameroon.

Introduction: Depending on the microenvironment, γδ T cells may assume characteristics similar to those of Th1, Th2, Th17, regulatory T cells or antigen presenting cells. Despite the wide documentation of the effect of Th1/Th2 balance on pregnancy associated malaria and outcomes, there are no reports on the relationship between γδ T cell phenotype change and Placental Malaria (PM) with pregnancy outcomes. This study sought to investigate the involvement of γδ T cells and its subsets in placental Plasmodium falciparum malaria. Methods: In a case-control study conducted in Yaoundé, Cameroon from March 2022 to May 2023, peripheral, placental and cord blood samples were collected from 50 women at delivery (29 PM negative: PM- and 21 PM positive: PM+; as diagnosed by light microscopy). Hemoglobin levels were measured using hemoglobinometer. PBMCs, IVBMCs and CBMCs were isolated using histopaque-1077 and used to characterize total γδ T cell populations and subsets (Vδ1+, Vδ2+, Vδ1-Vδ2-) by flow cytometry. Results: Placental Plasmodium falciparum infection was associated with significant increase in the frequency of total γδ T cells in IVBMC and of the Vδ1+ subset in PBMC and IVBMC, but decreased frequency of the Vδ2+ subset in PBMC and IVBMC. The expression of the activation marker: HLA-DR, and the exhaustion markers (PD1 and TIM3) within total γδ T cells and subsets were significantly up-regulated in PM+ compared to PM- group. The frequency of total γδ T cells in IVBMC, TIM-3 expression within total γδ T cells and subsets in IVBMC, as well as HLA-DR expression within total γδ T cells and Vδ2+ subset in IVBMC were negatively associated with maternal hemoglobin levels. Furthermore, the frequency of total γδ T cells in PBMC and PD1 expression within the Vδ2+ subset in CBMC were negatively associated with birth weight contrary to the frequency of Vδ1-Vδ2- subset in PBMC and HLA-DR expression within the Vδ2+ subset in IVBMC which positively associated with maternal hemoglobin level and birth weight, respectively. Conclusion: The data indicate up-regulation of activated and exhausted γδ T cells in Plasmodium falciparum placental malaria, with effects on pregnancy outcomes including maternal hemoglobin level and birth weight.

Plasmodium infections and associated risk factors among parturients in Jawi district, northwest Ethiopia: a cross-sectional study.

BACKGROUND: Pregnant women have an increased risk of Plasmodium infections and disease. Malaria in pregnancy is a major public health problem in endemic areas. Assessment of the burden and risk factors of malaria in pregnancy across different malaria transmission settings is required to guide control strategies and for malaria elimination. Thus, the current study is generating such evidence from parturient women in northwest Ethiopia. METHODS: A cross-sectional study was conducted among 526 pregnant women admitted to the delivery rooms of selected health facilities in Jawi district, northwest Ethiopia, between November 2021 and July 2022. Data on the socio-demographic, clinical, obstetric, and malaria prevention practices of pregnant women were collected using interviewer-administered questionnaires and from women's treatment cards. Malaria was diagnosed by light microscopy, rapid diagnostic test, and multiplex real-time polymerase chain reaction. Risk factors for malaria were evaluated using bivariable and multivariable logistic regression models. A P-value of < 0.05 was considered statistically significant. RESULTS: Among the examined parturient women, 14.3% (95% CI 11.4-17.5%) had Plasmodium infections. The prevalence of peripheral, placental, and congenital malaria was 12.2% (95% CI 9.5-15.3%), 10.9% (95% CI 8.2-14.1%), and 3.7% (95% CI 2.3-6.1%), respectively. About 90.6% of peripheral and 92% of placental Plasmodium infections were asymptomatic. Plasmodium infection at parturiency was independently predicted by maternal illiteracy (AOR = 2.03, 95% CI 1.11-3.74), primigravidity (AOR = 1.88, 95% CI 1.01-3.49), lack of antenatal care follow-up (AOR = 2.28, 95% CI 1.04-5.03), and history of symptomatic malaria during pregnancy (AOR = 4.2, 95% CI 2.32-7.59). Moreover, the blood group O phenotype was significantly associated with placental malaria among the primiparae. CONCLUSIONS: Overall, asymptomatic Plasmodium infections were prevalent among parturients in northwest Ethiopia. Maternal illiteracy, primigravidity, lack of antenatal care follow-up, and history of symptomatic malaria during pregnancy were the risk factors for malaria during parturiency. Thus, promotion of a healthy pregnancy through ANC follow-up, strengthening malaria prevention and control practices, and screening of malaria in asymptomatic pregnant women are suggested to reduce its burden in pregnancy.

Malaria-specific Type 1 regulatory T cells are more abundant in first pregnancies and associated with placental malaria.

BACKGROUND: Malaria in pregnancy (MIP) causes higher morbidity in primigravid compared to multigravid women; however, the correlates and mechanisms underlying this gravidity-dependent protection remain incompletely understood. We aimed to compare the cellular immune response between primigravid and multigravid women living in a malaria-endemic region and assess for correlates of protection against MIP. METHODS: We characterised the second trimester cellular immune response among 203 primigravid and multigravid pregnant women enrolled in two clinical trials of chemoprevention in eastern Uganda, utilizing RNA sequencing, flow cytometry, and functional assays. We compared responses across gravidity and determined associations with parasitaemia during pregnancy and placental malaria. FINDINGS: Using whole blood RNA sequencing, no significant differentially expressed genes were identified between primigravid (n = 12) and multigravid (n = 11) women overall (log 2(FC) > 2, FDR < 0.1). However, primigravid (n = 49) women had higher percentages of malaria-specific, non-naïve CD4+ T cells that co-expressed IL-10 and IFNγ compared with multigravid (n = 85) women (p = 0.000023), and higher percentages of these CD4+ T cells were associated with greater risks of parasitaemia in pregnancy (Rs = 0.49, p = 0.001) and placental malaria (p = 0.0073). These IL-10 and IFNγ co-producing CD4+ T cells had a genomic signature of Tr1 cells, including expression of transcription factors cMAF and BATF and cell surface makers CTLA4 and LAG-3. INTERPRETATION: Malaria-specific Tr1 cells were highly prevalent in primigravid Ugandan women, and their presence correlated with a higher risk of malaria in pregnancy. Understanding whether suppression of Tr1 cells plays a role in naturally acquired gravidity-dependent immunity may aid the development of new vaccines or treatments for MIP. FUNDING: This work was funded by NIH (PO1 HD059454, U01 AI141308, U19 AI089674, U01 AI155325, U01 AI150741), the March of Dimes (Basil O'Connor award), and the Bill and Melinda Gates Foundation (OPP 1113682).

Genetic diversity of Plasmodium vivax isolates from pregnant women in the Western Brazilian Amazon: a prospective cohort study.

Background: Each year, 92 million pregnant women are at risk of contracting malaria during pregnancy, with the underestimation of the mortality and morbidity burden associated with Plasmodium vivax. During pregnancy, P. vivax infection is associated with low birth weight, maternal anaemia, premature delivery, and stillbirth. In the State of Acre (Brazil), high transmission leaves pregnant women at greater risk of contracting malaria and having a greater number of recurrences. The study of genetic diversity and the association of haplotypes with adverse pregnancy effects is of great importance for the control of the disease. Here we investigate the genetic diversity of P. vivax parasites infecting pregnant women across their pregnancies. Methods: P. vivax DNA was extracted from 330 samples from 177 women followed during pregnancy, collected in the State of Acre, Brazil. All samples were negative for Plasmodium falciparum DNA. Sequence data for the Pvmsp1 gene was analysed alongside data from six microsatellite (MS) markers. Allelic frequencies, haplotype frequencies, expected heterozygosity (HE) were calculated. Whole genome sequencing (WGS) was conducted on four samples from pregnant women and phylogenetic analysis performed with other samples from South American regions. Findings: Initially, the pregnant women were stratified into two groups-1 recurrence and 2 or more recurrences-in which no differences were observed in clinical gestational outcomes or in placental histological changes between the two groups. Then we evaluated the parasites genetically. An average of 18.5 distinct alleles were found at each of the MS loci, and the HE calculated for each marker indicates a high genetic diversity occurring within the population. There was a high percentage of polyclonal infections (61.7%, 108/175), and one haplotype (H1) occurred frequently (20%), with only 9 of the haplotypes appearing in more than one patient. Interpretation: Most pregnant women had polyclonal infections that could be the result of relapses and/or re-infections. The high percentage of H1 parasites, along with the low frequency of many other haplotypes are suggestive of a clonal expansion. Phylogenetic analysis shows that P. vivax population within pregnant women clustered with other Brazilian samples in the region. Funding: FAPESP and CNPq - Brazil.

The Rapid and Spontaneous Postpartum Clearance of Plasmodium falciparum Is Related to Expulsion of the Placenta.

Parasitemia among pregnant women with protective immunity to Plasmodium falciparum malaria is often dominated by VAR2CSA-positive infected erythrocytes (IEs). VAR2CSA mediates sequestration of IEs in the placenta. We hypothesized that the previously observed spontaneous postpartum clearance of parasitemia in such women is related to the expulsion of the placenta, which removes the sequestration focus of VAR2CSA-positive IEs. We assessed parasitemias and gene transcription before and shortly after delivery in 17 Ghanaian women. The precipitous decline in parasitemia postpartum was accompanied by selective reduction in transcription of the gene encoding VAR2CSA. Our findings provide a mechanistic explanation for the earlier observation.

Disulfide bond and crosslinking analyses reveal inter-domain interactions that contribute to the rigidity of placental malaria VAR2CSA structure and formation of CSA binding channel.

VAR2CSA, a multidomain Plasmodium falciparum protein, mediates the adherence of parasite-infected red blood cells to chondroitin 4-sulfate (C4S) in the placenta, contributing to placental malaria. Therefore, detailed understanding of VAR2CSA structure likely help developing strategies to treat placental malaria. The VAR2CSA ectodomain consists of an N-terminal segment (NTS), six Duffy binding-like (DBL) domains, and three interdomains (IDs) present in sequence NTS-DBL1x-ID1-DBL2x-ID2-DBL3x-DBL4ε-ID3-DBL5ε-DBL6ε. Recent electron microscopy studies showed that VAR2CSA is compactly organized into a globular structure containing C4S-binding channel, and that DBL5ε-DBL6ε arm is attached to the NTS-ID3 core structure. However, the structural elements involved in inter-domain interactions that stabilize the VAR2CSA structure remain largely not understood. Here, limited proteolysis and peptide mapping by mass spectrometry showed that VAR2CSA contains several inter-domain disulfide bonds that stabilize its compact structure. Chemical crosslinking-mass spectrometry showed that all IDs interact with DBL4ε; additionally, IDs interact with other DBL domains, demonstrating that IDs are the key structural scaffolds that shape the functional NTS-ID3 core. Ligand binding analysis suggested that NTS considerably restricts the C4S binding. Overall, our study revealed that inter-domain disulfide bonds and interactions between IDs and DBL domains contribute to the stability of VAR2CSA structural architecture and formation of C4S-binding channel.

Acquisition of antibodies that block Plasmodium falciparum adhesion to placental receptor chondroitin sulfate A with increasing gravidity in Malian women.

In malaria-endemic areas, pregnant women are more susceptible to Plasmodium falciparum infection, especially primigravidae. During pregnancy, parasites sequester in the placenta and bind to the receptor chondroitin sulfate (CSA). This unique adhesion is mediated by the parasite protein VAR2CSA expressed on the surface of infected erythrocytes (IE). Placental malaria is associated with poor pregnancy outcomes including perinatal mortality, preterm delivery, small for gestational age (SGA) and low birthweight deliveries. Over successive pregnancies, women acquire functional antibodies that inhibit IE adhesion to CSA. Here, we examine the development of anti-adhesion activity and the breadth of anti-adhesion activity as a function of number of previous pregnancies, using samples collected from pregnant women living in an area with high seasonal malaria transmission. Women reached plateau levels of anti-adhesion activity and breadth of anti-adhesion activity after 5 pregnancies. We related the level of anti-adhesion activity and reactivity with surface IE to SGA 19/232 pregnancies resulted in SGA, and report that an increase of 10% in median anti-adhesion activity reduced the odds of SGA by 13% and this relationship approached significance. Further, at an anti-adhesion activity level of 43.7%, an increase of 10% in the breadth of activity significantly reduced the odds of SGA by 21.5%. Antibodies that recognize IE surface increased over successive pregnancies, but were not associated with a reduction in SGA. These results can serve as a guideline for assessing vaccine candidates aiming to reduce poor pregnancy outcomes associated with placental malaria.

Impact and operational feasibility of adding malaria infection screening using an ultrasensitive RDT for placental and fetal outcomes in an area of high IPTP-SP coverage in Burkina Faso: the ASSER MALARIA pilot study protocol.

BACKGROUND: Malaria infection during pregnancy (MIP) is not only deleterious to the woman, but it also puts her fetus at increased risk of adverse outcomes, such as preterm delivery, low birth weight, and intrauterine growth retardation. Additionally, all-cause mortality during the first year of life in babies born to women with malaria during pregnancy is also increased. Many interventions such as IPTp-SP and long-lasting insecticidal nets have proven to be efficient at reducing malaria in pregnancy burden but adherence to recommended policies remains poor. In sub-Saharan Africa, malaria in pregnancy is often asymptomatic and many malaria infections may be missed due to the inadequate performance of the current rapid diagnostic test to detect low-level parasitemias. Therefore, additional strategies such as intermittent screening with ultrasensitive rapid diagnostic tests and treatment with an effective artemisinin-based combination therapy in addition to IPTp-SP could reduce placental malaria, peripheral malaria infection at delivery, and low birth weight. METHODS: This pilot 2-group randomized open trial with a nested qualitative social behavioral will be carried out in Nanoro district in which 340 pregnant women will be recruited. Pregnant women will be randomized into two groups and followed on a monthly basis until delivery. In the intervention group, monthly screening using ultrasensitive rapid diagnostic tests and treatment of those found to be infected with dihydroartemisinin-piperaquine will be performed. In addition, a reminder will be sent to increase the uptake of IPTp-SP doses per woman. During scheduled and unscheduled visits, malaria infection, hemoglobin level, and other clinical outcomes will be assessed and compared by the group. The primary feasibility outcome will evaluate the study site's capacity to enroll participants and the women's perception and acceptability of the intervention. The primary clinical outcome will be the prevalence of placental malaria at delivery. DISCUSSION: The present protocol aims to evaluate the feasibility on a large-scale and also to demonstrate the impact and the operational feasibility of additional screening with ultrasensitive rapid diagnostic tests and treatment with DHA-PQ on placental malaria, low birth weight, and peripheral malaria infection at delivery in a high-burden setting in Burkina Faso. TRIAL REGISTRATION: ClinicalTrials.gov , ID: NCT04147546 (14 October 2019).

Assessing the relationship between gravidity and placental malaria among pregnant women in a high transmission area in Ghana.

BACKGROUND: Malaria infection during pregnancy can cause significant morbidity and mortality to a pregnant woman, her fetus and newborn. In areas of high endemic transmission, gravidity is an important risk factor for infection, but there is a complex relationship with other exposure-related factors, and use of protective measures. This study investigated the association between gravidity and placental malaria (PM), among pregnant women aged 14-49 in Kintampo, a high transmission area of Ghana. METHODS: Between 2008 and 2011, as part of a study investigating the association between PM and malaria in infancy, pregnant women attending antenatal care (ANC) clinics in the study area were enrolled and followed up until delivery. The outcome of PM was assessed at delivery by placental histopathology. Multivariable logistic regression analyses were used to investigate the association between gravidity and PM, identify other key risk factors, and control for potential confounders. Pre-specified effect modifiers including area of residence, socio-economic score (SES), ITN use and IPTp-SP use were explored. RESULTS: The prevalence of PM was 65.9% in primigravidae, and 26.5% in multigravidae. After adjusting for age, SES and relationship status, primigravidae were shown to have over three times the odds of PM compared to multigravidae, defined as women with 2 or more previous pregnancies [adjusted OR = 3.36 (95% CI 2.39-4.71), N = 1808, P < 0.001]. The association appeared stronger in rural areas [OR for PG vs. MG was 3.79 (95% CI 3.61-5.51) in rural areas; 2.09 (95% CI 1.17-3.71) in urban areas; P for interaction = 0.07], and among women with lower socio-economic scores [OR for PG vs. MG was 4.73 (95% CI 3.08-7.25) amongst women with lower SES; OR = 2.14 (95% CI 1.38-3.35) among women with higher SES; P for interaction = 0.008]. There was also evidence of lower risk among primigravidae with better use of the current preventive measures IPTp and LLIN. CONCLUSIONS: The burden of PM is most heavily focused on primigravidae of low SES living in rural areas of high transmission. Programmes should prioritize primigravidae and young women of child-bearing age for interventions such as LLIN distribution, educational initiatives and treatment to reduce the burden of malaria in first pregnancy.

Impact of oxidative stress in response to malarial infection during pregnancy: Complications, histological changes, and pregnancy outcomes.

Background and Objectives: Pregnancy malaria is a major underestimated global public health problem. To understand the involvement of oxidative stress (OS) in the pathophysiology of placental malaria, OS biomarkers, malondialdehyde (MDA), uric acid (UA), and superoxide dismutase (SOD) levels were analyzed and correlated to placental histopathological changes and pregnancy outcomes. Methods: A hospital-based study was conducted in Mangaluru, Karnataka, India, to analyze the changes in hematological parameters and the serum OS biomarker levels. Histological analysis of placenta, associated complications, and pregnancy outcomes were compared using Kruskal-Wallis test, and pairwise comparison between two groups was made by Mann-Whitney U-test. Correlations were calculated by Pearson's and Spearman's rank correlations. Results: Among 105 pregnant women, 34 were healthy controls and the infected group comprised of Plasmodium Vivax (Pv) (n = 48), Plasmodium falciparum (Pf) (n = 13), and mixed (n = 10) malaria infections. Of 71 infected cases, 67.6% had mild malaria, whereas 32.4% had severe malaria. The white blood cell and C-reactive protein levels were found to increase, whereas hemoglobin, red blood cell, and platelet levels decreased during both types of malarial infections. The MDA and UA values increased and SOD levels decreased particularly during severe Pf infections. Histological changes such as syncytial knots, syncytial ruptures, and fibrinoid necrosis were observed particularly during Pf infections and leukocyte infiltration was observed in Pv malaria. Conclusion: Evaluation of MDA, UA, and SOD levels can serve as an indicator of OS during pregnancy malaria. The OS during pregnancy may lead to complications such as severe anemia, pulmonary edema, intra uterine growth retardation, premature delivery, and low birth weight, not only during Pf but also in Pv malaria. It is important to create awareness among rural and immigrant population residing in Mangaluru and its surroundings about required preventive measures and free government-supported antenatal care services.

Potential pharmacologic interventions targeting TLR signaling in placental malaria.

Complications from placental malaria cause poor pregnancy outcomes, including low birthweight, preterm delivery, and stillbirths. Many of these complications are driven by maternal innate proinflammatory responses to the sequestration of Plasmodium falciparum in the placenta. However, recent studies show that, in reaction to maternal innate immune responses that are detrimental to the fetus, the fetus mounts innate immune counter-responses that ameliorate pregnancy outcomes. Such fetal-maternal conflict in placental malaria has potential for pharmacologic modulation for better pregnancy outcomes. Here, we discuss placental malaria pathogenesis, its complications, and the role of innate immunity and fetal-maternal innate immune conflict in placental malaria. Finally, we discuss pharmacologic immunomodulatory strategies and agents with the potential to improve placental malaria outcomes.

Polymorphic Molecular Signatures in Variable Regions of the Plasmodium falciparum var2csa DBL3x Domain Are Associated with Virulence in Placental Malaria.

The Plasmodium falciparum protein VAR2CSA allows infected erythrocytes to accumulate within the placenta, inducing pathology and poor birth outcomes. Multiple exposures to placental malaria (PM) induce partial immunity against VAR2CSA, making it a promising vaccine candidate. However, the extent to which VAR2CSA genetic diversity contributes to immune evasion and virulence remains poorly understood. The deep sequencing of the var2csa DBL3X domain in placental blood from forty-nine primigravid and multigravid women living in malaria-endemic western Kenya revealed numerous unique sequences within individuals in association with chronic PM but not gravidity. Additional analysis unveiled four distinct sequence types that were variably present in mixed proportions amongst the study population. An analysis of the abundance of each of these sequence types revealed that one was inversely related to infant gestational age, another was inversely related to placental parasitemia, and a third was associated with chronic PM. The categorization of women according to the type to which their dominant sequence belonged resulted in the segregation of types as a function of gravidity: two types predominated in multigravidae whereas the other two predominated in primigravidae. The univariate logistic regression analysis of sequence type dominance further revealed that gravidity, maternal age, placental parasitemia, and hemozoin burden (within maternal leukocytes), reported a lack of antimalarial drug use, and infant gestational age and birth weight influenced the odds of membership in one or more of these sequence predominance groups. Cumulatively, these results show that unique var2csa sequences differentially appear in women with different PM exposure histories and segregate to types independently associated with maternal factors, infection parameters, and birth outcomes. The association of some var2csa sequence types with indicators of pathogenesis should motivate vaccine efforts to further identify and target VAR2CSA epitopes associated with maternal morbidity and poor birth outcomes.

Tackling variants with antibodies.

Antibodies targeting the protein that causes placental malaria can recognise multiple variants of the protein, which may help guide the development of new vaccines to protect pregnant women from malaria.

Plasmodium falciparum in Aotus nancymaae: A New Model for Placental Malaria.

Plasmodium falciparum-infected erythrocytes that display the variant surface antigen VAR2CSA bind chondroitin sulfate A (CSA) to sequester in placental intervillous spaces, causing severe sequelae for mother and offspring. Here, we establish a placental malaria (PM) monkey model. Pregnant Aotus infected with CSA-binding P. falciparum CS2 parasites during the third trimester developed pronounced sequestration of late-stage parasites in placental intervillous spaces that express VAR2CSA and bind specifically to CSA. Similar to immune multigravid women, a monkey infected with P. falciparum CS2 parasites over successive pregnancies acquired antibodies against VAR2CSA, with potent functional activity that was boosted upon subsequent pregnancy infections. Aotus also developed functional antibodies after multiple acute PM episodes and subsequent VAR2CSA immunization. In summary, P. falciparum infections in pregnant Aotus monkeys recapitulate all the prominent features of human PM infection and immunity, and this model can be useful for basic mechanistic studies and preclinical studies to qualify candidate PM vaccines. Clinical Trials Registration: NCT02471378.

An Invariant Protein That Colocalizes With VAR2CSA on Plasmodium falciparum-Infected Red Cells Binds to Chondroitin Sulfate A.

BACKGROUND: Plasmodium falciparum-infected red blood cells (iRBCs) bind and sequester in deep vascular beds, causing malaria-related disease and death. In pregnant women, VAR2CSA binds to chondroitin sulfate A (CSA) and mediates placental sequestration, making it the major placental malaria (PM) vaccine target. METHODS: In this study, we characterize an invariant protein associated with PM called P falciparum chondroitin sulfate A ligand (PfCSA-L). RESULTS: Recombinant PfCSA-L binds both placental CSA and VAR2CSA with nanomolar affinity, and it is coexpressed on the iRBC surface with VAR2CSA. Unlike VAR2CSA, which is anchored by a transmembrane domain, PfCSA-L is peripherally associated with the outer surface of knobs through high-affinity protein-protein interactions with VAR2CSA. This suggests that iRBC sequestration involves complexes of invariant and variant surface proteins, allowing parasites to maintain both diversity and function at the iRBC surface. CONCLUSIONS: The PfCSA-L is a promising target for intervention because it is well conserved, exposed on infected cells, and expressed and localized with VAR2CSA.

The Effect of Intermittent Preventive Treatment of Malaria During Pregnancy and Placental Malaria on Infant Risk of Malaria.

BACKGROUND: Intermittent preventive treatment of malaria during pregnancy (IPTp) with dihydroartemisinin-piperaquine (DP) provides greater protection from placental malaria than sulfadoxine-pyrimethamine (SP). Some studies suggest placental malaria alters risk of malaria infection in infants, but few have quantified the effect of IPTp on infant susceptibility to malaria. METHODS: Infants born to women enrolled in a randomized clinical trial comparing IPTp-SP and IPTp-DP in Malawi were followed from birth to 24 months to assess effect of IPTp and placental malaria on time to first malaria episode and Plasmodium falciparum incidence. RESULTS: In total, 192 infants born to mothers randomized to IPTp-SP and 195 randomized to IPTp-DP were enrolled. Infants in IPTp exposure groups did not differ significantly regarding incidence of clinical malaria (incidence rate ratio [IRR], 1.03; 95% confidence interval [CI], .58-1.86) or incidence of infection (IRR, 1.18; 95% CI, .92-1.55). Placental malaria exposure was not associated with incidence of clinical malaria (IRR, 1.03; 95% CI, .66-1.59) or infection (IRR, 1.15; 95% CI, .88-1.50). Infant sex, season of birth, and maternal gravidity did not confound results. CONCLUSIONS: We did not find evidence that IPTp regimen or placental malaria exposure influenced risk of malaria during infancy in this population. Clinical Trials Registration. NCT03009526.

HIF-1α regulated pathomechanism of low birth weight through angiogenesis factors in placental Plasmodium vivax infection.

Background: Malaria in pregnancy leads to placental malaria. The primary pathogenesis of the complex fetal implications in placental malaria is tissue hypoxia due to sequestrations of Plasmodium falciparum-infected erythrocytes in the placenta. However, the pathomechanism of placental Plasmodium vivax infection has not been thoroughly investigated. Hypoxia-inducible factor-1α (HIF-1α) is a key transcriptional mediator of the response to hypoxic conditions, which interacts with the change and imbalances of many chemical mediators, including angiogenic factors, leading to fetal growth abnormality. Methods: This study was conducted cross-sectionally in Maumere, Sikka Regency, East Nusa Tenggara Province, previously known as one of the malaria endemic areas with a high incidence of low birth weight (LBW) cases. This study collected peripheral and umbilical blood samples and placental tissues from mothers who delivered their babies with LBW at the TC Hiller Regional Hospital. All of the blood samples were examined for parasites by microscopic and PCR techniques, while the plasma levels of VEGF, PlGF, VEGFR-1, VEGFR-2, and HIF-1α were determined using ELISA. The sequestration of infected erythrocytes and hemozoin was determined from placental histological slides, and the expression of placenta angiogenic factors was observed using the immunofluorescent technique. Results: In this study, 33 cases had complete data to be analyzed. Of them, 19 samples were diagnosed as vivax malaria and none of falciparum malaria. There were significant differences in Δ 10th percentile growth curve of baby's body weights and also all angiogenic factors in placental tissues {VEGF, PlGF, and VEGFR-1, VEGFR-2, and HIF-1α} between those infected and not infected cases (p<0.05), but not for VEGF and VEGFR-2 in the plasma. Conclusion: This study indicated that Plasmodium vivax sequestration may promote LBW through alterations and imbalances in angiogenic factors led by HIF-1α.

PfEMP1-Specific Immunoglobulin G Reactivity Among Beninese Pregnant Women With Sickle Cell Trait.

BACKGROUND: Sickle cell trait (HbAS) protects against severe Plasmodium falciparum malaria but not against placental malaria (PM). In this study, P falciparum erythrocyte membrane protein (PfEMP1)-specific antibodies were measured in HbAA and HbAS Beninese pregnant women as a proxy of exposure to specific PfEMP1 variants. METHODS: Plasma samples collected at delivery from 338 HbAA and 63 HbAS women were used to measure immunoglobulin (Ig)G levels to 6 recombinant PfEMP1 proteins and 3 corresponding native proteins expressed on the infected erythrocyte (IE) surface. Immunoglobulin G-mediated inhibition of VAR2CSA+ IEs adhesion to chondroitin sulfate A (CSA) was also tested. RESULTS: Levels of PfEMP1-specific IgG were similar in the 2 groups, except for native IT4VAR09 on IEs, where IgG levels were significantly higher in HbAS women. Adjusted odds ratios for women with positive IgG to HB3VAR06 and PFD1235w suggest a lower risk of infection with these virulent variants among HbAS individuals. The percentage of IEs binding to CSA did not differ between HbAA and HbAS women, but it correlated positively with levels of anti-VAR2CSA and parity. Women with PM had lower levels of anti-VAR2CSA-specific IgG and lower IgG-mediated inhibition of IE adhesion to CSA. CONCLUSIONS: The findings support similar malaria exposure in HbAA and HbAS women and a lack of HbAS-dependent protection against placental infection among pregnant women.

The Relationship Between Fetal Weight with Sequestration of Infected Erythrocyte, Monocyte Infiltration, and Malaria Pigment Deposition in Placenta of Mother Giving Birth Suffering from Plasmodium Vivax Infection.

BACKGROUND: Malaria in pregnancy can cause fatal complications by parasite sequestration mechanism, which can cause monocyte infiltration in the intervillous space. P. vivax infection was significantly associated with malaria pigment in the placenta, indicating past subclinical infections. OBJECTIVE: This study aimed to determine the mechanism of P. vivax in the pathogenesis of placental malaria and its relationship with LBW. METHODS: This study was observational analytic with a cross-sectional approach. Placental tissue samples were obtained from pregnant women with LBW babies during delivery in Maumere, Nusa Tenggara Timur. The samples used in this study were confirmed by a polymerase chain reaction and consisted of 25 samples with 12 positive and 13 negative samples. Placental tissue samples were made with Hematoxylin-Eosin staining and observed under 1000x magnification at 100 fields using a light microscope. Parasite density, monocyte infiltration, and parasite pigments deposition were calculated. RESULTS: Microscopic observation revealed that there was a significant difference in infected erythrocytes sequestration between groups. Interestingly, monocyte and malaria pigments accumulation were found in malaria-positive and -negative groups, and no significant difference between groups. The correlation test showed no significant relationship between monocyte infiltration and LBW in the malaria-positive and -negative group and between parasite pigments and LBW in both groups. Moreover, there was no significant correlation between parasite density and LBW in the positive and negative groups. CONCLUSION: P. vivax infection causes acute, sub-acute, and chronic placental malaria in subclinical infected pregnant women in Maumere, Nusa Tenggara Timur that might cause an LBW baby.

Correlation between CD 34 and CD 68 expression in placental malaria with maternal anemia.

BACKGROUND: Malaria is the second most life-threatening infectious disease in Indonesia, causing approximately 1-3 million deaths annually. Histopathologic studies assessing CD 68 and CD 34 protein expression in placental malaria and its association with maternal anemia are essential to determine the prognosis of malaria in pregnancy. MATERIALS AND METHODS: This cross-sectional study was carried out in 2017. Thirty biopsy samples of human placental tissue were obtained from Timika and Sumba, and ten normal biopsy samples were taken from the Pathological Anatomy Department of Cipto Mangunkusumo General Hospital as comparisons. CD 34 and CD 68 protein expressions were determined using immunohistochemistry, and the resulting data were analyzed using SPSS. RESULTS: Average hemoglobin (Hb) level was 9.5 mg/dL, 11.5 mg/dL, and 9.9 mg/dL in acute infection, chronic infection, and latent infection, respectively. A positive correlation was found between CD 68 protein expression and maternal Hb level. No correlation was found between CD34 expression and maternal anemia. CONCLUSIONS: CD 68 expression in placental tissue biopsy from Timika and Sumba residents with placental malaria was shown to be positively correlated with maternal anemia. Immunohistochemical examination of CD 68 may play a role in the early diagnosis of malaria.