Oxidative Stress: A Potential Therapeutic Target in Placental Malaria

Inhibition of Heme Oxygenase-1 by Zinc Protoporphyrin IX Improves Adverse Pregnancy Outcomes in Malaria During Early Gestation

The enzyme heme oxygenase-1 (HO-1) has cytoprotective effects by catalyzing the degradation of heme to produce carbon monoxide, iron and biliverdin. Furthermore, HO-1 activity has been associated with successful pregnancy. On the other hand, in the context of certain inflammatory conditions, HO-1 can induce iron overload and cell death. To investigate the role of HO-1 in gestational malaria, pregnant BALB/c mice were infected with Plasmodium berghei ANKA in early, mid and late gestation. We found that malaria affected the pregnancy outcome in the three periods evaluated. However, only poor pregnancy outcomes in early pregnancy were related to HO-1 upregulation, iron overload, lipid peroxidation and necrosis of the decidua, which were prevented by HO-1 inhibition. In conclusion, HO-1 expression must be finely tuned in gestational malaria to avoid the deleterious effect of increased enzyme activity.

Oxidative Stress in Malaria: Potential Benefits of Antioxidant Therapy

Malaria is an infectious disease and a serious public health problem in the world, with 3.3 billion people in endemic areas in 100 countries and about 200 million new cases each year, resulting in almost 1 million deaths in 2018. Although studies look for strategies to eradicate malaria, it is necessary to know more about its pathophysiology to understand the underlying mechanisms involved, particularly the redox balance, to guarantee success in combating this disease. In this review, we addressed the involvement of oxidative stress in malaria and the potential benefits of antioxidant supplementation as an adjuvant antimalarial therapy.

A novel murine model of post-implantation malaria-induced preterm birth

Despite major advances made in malaria treatment and control over recent decades, the development of new models for studying disease pathogenesis remains a vital part of malaria research efforts. The study of malaria infection during pregnancy is particularly reliant on mouse models, as a means of circumventing many challenges and costs associated with pregnancy studies in endemic human populations. Here, we introduce a novel murine model that will further our understanding of how malaria infection affects pregnancy outcome. When C57BL/6J (B6) mice are infected with Plasmodium chabaudi chabaudi AS on either embryonic day (E) 6.5, 8.5, or 10.5, preterm birth occurs in all animals by E16.5, E17.5, or E18.5 respectively, with no evidence of intrauterine growth restriction. Despite having the same outcome, we found that the time to delivery, placental inflammatory and antioxidant transcript upregulation, and the relationships between parasitemia and transcript expression prior to preterm birth differed based on the embryonic day of infection. On the day before preterm delivery, E6.5 infected mice did not experience significant upregulation of the inflammatory or antioxidant gene transcripts examined; however, peripheral and placental parasitemia correlated positively with Il1β, Cox1, Cat, and Hmox1 placental transcript abundance. E8.5 infected mice had elevated transcripts for Ifnγ, Tnf, Il10, Cox1, Cox2, Sod1, Sod2, Cat, and Nrf2, while Sod3 was the only transcript that correlated with parasitemia. Finally, E10.5 infected mice had elevated transcripts for Ifnγ only, with a tendency for Tnf transcripts to correlate with peripheral parasitemia. Tumor necrosis factor deficient (TNF-/-) and TNF receptor 1 deficient (TNFR1-/-) mice infected on E8.5 experienced preterm birth at the same time as B6 controls. Further characterization of this model is necessary to discover the mechanism(s) and/or trigger(s) responsible for malaria-driven preterm birth caused by maternal infection during early pregnancy.

Hydroethanolic Extracts of Senna alata Leaves Possess Antimalarial Effects and Reverses Haematological and Biochemical Pertubation in Plasmodium berghei-infected Mice

The current work investigated the chemical profile, antimalarial potential and capacity of hydroethanolic Senna alata extract (SAE) to reverse hematological and biochemical pertubation in Plasmodium berghei infected mice. Results of the phytochemical analysis revealed the presence of alkaloids, flavonoids, phenolics, tannins, terpenoids, saponins, steroids and cardiac glycosides. Total phenolic and flavonoid content was estimated to be 45.29 ± 2.34 mg GAE/g and 25.22 ± 2.26 mg QE/g respectively. In vitro analysis of the extract also confirmed its antioxidant property. Results of the test for prophylaxis of P. berghei indicated that SAE suppressed parasitemia significantly in treated groups in a dose dependent manner when compared with negative control group. Similarly, SAE improved the mean survival time (MST) and packed cell volume (PCV) of infected mice. The test for curative effect showed that SAE significantly suppressed parasitemia to 4.50 ± 1.05% compared to untreated group 29.83 ± 3.49%. Results of liver and kidney functions indices of treated animals indicated that whereas infection with P. berghei caused increase in the levels of AST, ALT, ALP, urea and creatinine, treatment with SAE significantly reversed the perturbation. Similarly, infected mice were dyslipidemic with concomitant increased activity of HMG CoA reductase and decreased activity of antioxidant enzymes with increase in lipid peroxides levels. However, these alterations were significantly reversed by administration of SAE. Results of this study shows that Senna alata possess antimalarial activity and therefore justify the traditional use of plant for the treatment of malaria.

Molecular mechanisms of hematological and biochemical alterations in malaria: A review

Malaria is a dangerous disease that contributes to millions of hospital visits and hundreds of thousands of deaths, especially in children residing in sub-Saharan Africa. Although several interventions such as vector control, case detection, and treatment are already in place, there is no substantive reduction in the disease burden. Several studies in the past have reported the emergence of resistant strains of malaria parasites (MPs) and mosquitoes, and poor adherence and inaccessibility to effective antimalarial drugs as the major factors for this persistent menace of malaria infections. Moreover, victory against MP infections for many years has been hampered by an incomplete understanding of the complex nature of malaria pathogenesis. Very recent studies have identified different complex interactions and hematological alterations induced by malaria parasites. However, no studies have hybridized these alterations for a better understanding of Malaria pathogenesis. Hence, this review thoroughly discusses the molecular mechanisms of all reported hematological and biochemical alterations induced by MPs infections. Specifically, the mechanisms in which MP-infection induces anemia, thrombocytopenia, leukopenia, dyslipidemia, hypoglycemia, oxidative stress, and liver and kidney malfunctions were presented. The study also discussed how MPs evade the host's immune response and suggested strategies to limit evasion of the host's immune response to combat malaria and its complications.

Myeloperoxidase and Other Markers of Neutrophil Activation Associate With Malaria and Malaria/HIV Coinfection in the Human Placenta

Introduction

Placental malaria (PM) is characterized by accumulation of inflammatory leukocytes in the placenta, leading to poor pregnancy outcomes. Understanding of the underlying mechanisms remains incomplete. Neutrophils respond to malaria parasites by phagocytosis, generation of oxidants, and externalization of Neutrophil Extracellular Traps (NETs). NETs drive inflammation in malaria but evidence of NETosis in PM has not been reported. Neutrophil activity in the placenta has not been directly investigated in the context of PM and PM/HIV-co-infection.

Methods

Using peripheral and placental plasma samples and placental tissue collected from Kenyan women at risk for malaria and HIV infections, we assessed granulocyte levels across all gravidities and markers of neutrophil activation, including NET formation, in primi- and secundigravid women, by ELISA, western blot, immunohistochemistry and immunofluorescence.

Results

Reduced peripheral blood granulocyte numbers are observed with PM and PM/HIV co-infection in association with increasing parasite density and placental leukocyte hemozoin accumulation. In contrast, placental granulocyte levels are unchanged across infection groups, resulting in enhanced placental: peripheral count ratios with PM. Within individuals, PM- women have reduced granulocyte counts in placental relative to peripheral blood; in contrast, PM stabilizes these relative counts, with HIV coinfection tending to elevate placental counts relative to the periphery. In placental blood, indicators of neutrophil activation, myeloperoxidase (MPO) and proteinase 3 (PRTN3), are significantly elevated with PM and, more profoundly, with PM/HIV co-infection, in association with placental parasite density and hemozoin-bearing leukocyte accumulation. Another neutrophil marker, matrix metalloproteinase (MMP9), together with MPO and PRTN3, is elevated with self-reported fever. None of these factors, including the neutrophil chemoattractant, CXCL8, differs in relation to infant birth weight or gestational age. CXCL8 and MPO levels in the peripheral blood do not differ with infection status nor associate with birth outcomes. Indicators of NETosis in the placental plasma do not vary with infection, and while structures consistent with NETs are observed in placental tissue, the results do not support an association with PM.

Conclusions

Granulocyte levels are differentially regulated in the peripheral and placental blood in the presence and absence of PM. PM, both with and without pre-existing HIV infection, enhances neutrophil activation in the placenta. The impact of local neutrophil activation on placental function and maternal and fetal health remains unclear. Additional investigations exploring how neutrophil activation and NETosis participate in the pathogenesis of malaria in pregnant women are needed.

Mitochondrial and Oxidative Unbalance in Placentas from Mothers with SARS-CoV-2 Infection

SARS-CoV-2 infection has been related to adverse pregnancy outcomes. A placental role in protecting the fetus from SARS-CoV-2 infection has been documented. Nevertheless, it is still unclear how the placenta is affected in SARS-CoV-2 infection. Here we assessed placental mitochondrial (mt) and oxidative features in COVID-19 and healthy mothers. mtDNA levels, DNA oxidative damage, expression levels of genes involved in antioxidant defenses, mitochondrial dynamics and respiratory chain subunits were investigated in placentas from singleton pregnancies of 30 women with SARS-CoV-2 infection during the third trimester (12 asymptomatic, 18 symptomatic) and 16 controls. mtDNA levels decreased in COVID-19 placentas vs. controls and inversely correlated with DNA oxidative damage, which increased in the symptomatic group. Antioxidant gene expressions decreased in SARS-CoV-2 mothers (CAT, GSS). Symptomatic cases also showed a lower expression of respiratory chain (NDUFA9, SDHA, COX4I1) and mt dynamics (DNM1L, FIS1) genes. Alterations in placental mitochondrial features and oxidative balance in COVID-19-affected mothers might be due to the impaired intrauterine environment, generated by systemic viral effects, leading to a negative vicious circle that worsens placental oxidative stress and mitochondrial efficiency. This likely causes cell homeostasis dysregulations, raising the potential of possible long-term effects.

A proteomic glimpse into the effect of antimalarial drugs on Plasmodium falciparum proteome towards highlighting possible therapeutic targets

There is no effective vaccine against malaria; therefore, chemotherapy is to date the only choice to fight against this infectious disease. However, there is growing evidences of drug-resistance mechanisms in malaria treatments. Therefore, the identification of new drug targets is an urgent need for the clinical management of the disease. Proteomic approaches offer the chance of determining the effects of antimalarial drugs on the proteome of Plasmodium parasites. Accordingly, we reviewed the effects of antimalarial drugs on the Plasmodium falciparum proteome pointing out the relevance of several proteins as possible drug targets in malaria treatment. In addition, some of the P. falciparum stage-specific altered proteins and parasite-host interactions might play important roles in pathogenicity, survival, invasion and metabolic pathways and thus serve as potential sources of drug targets. In this review, we have identified several proteins, including thioredoxin reductase, helicases, peptidyl-prolyl cis-trans isomerase, endoplasmic reticulum-resident calcium-binding protein, choline/ethanolamine phosphotransferase, purine nucleoside phosphorylase, apical membrane antigen 1, glutamate dehydrogenase, hypoxanthine guanine phosphoribosyl transferase, heat shock protein 70x, knob-associated histidine-rich protein and erythrocyte membrane protein 1, as promising antimalarial drugs targets. Overall, proteomic approaches are able to partially facilitate finding possible drug targets. However, the integration of other 'omics' and specific pharmaceutical techniques with proteomics may increase the therapeutic properties of the critical proteins identified in the P. falciparum proteome.

Oxidative stress and anti-oxidants in asymptomatic malaria-positive patients: a hospital-based cross-sectional Nigerian study

Background

Asymptomatic malaria is a threat to malaria eradication program. Host-related factors (e.g., immunity, oxidative stress, anti-oxidants activities) associated with asymptomatic malaria remain a gray area in research. This study seeks to determine the serum level of oxidative stress and anti-oxidants in 130 symptomatic and asymptomatic patients with different intensities of malaria parasite infection from a hospital in Ibadan, Nigeria.

Results

The prevalence of infection was 48.5% among the respondents. Most of the patients with parasitemia were asymptomatic (64.7%). The mean titer value of malondialdehyde (MDA) was significantly higher (p < 0.05) among those with malaria infection (6.05 ± 0.60) compared with those who tested negative for malaria parasites (2.38 ± 0.28). Furthermore, the mean titer value of MDA was significantly higher (p < 0.05) among patients who showed symptoms of malaria (5.49 ± 0.77) compared with those without symptoms (2.93 ± 0.47). A strong positive relationship existed between MDA (r = 0.717, p < 0.05), glutathione peroxidase (GPx) (r = 0.695, p < 0.05), and density of infection. On the other hand, a weak negative correlation existed between intensity and superoxide dismutase (SOD) (r = − 0.115, p > 0.05) and glutathione (GSH) (r = − 0.278, p > 0.05). The level of SOD and GSH also decreased significantly (p < 0.05) with an increase in MDA level.

Conclusions

This study showed that lipid peroxidation did not only increase in positive patients, it also rises in patients with clinical symptoms of malaria. Furthermore, a similar level of anti-oxidant responses was observed in both symptomatic and asymptomatic malaria patients. There is a need to inform health policies that encourage routine diagnosis and treatment of malaria in apparently healthy people if the malaria elimination goal is to be achieved in Africa.

The Preventive Effects of Xanthohumol on Vascular Calcification Induced by Vitamin D3 Plus Nicotine

Vascular calcification (VC) is highly prevalent in patients with atherosclerosis, chronic kidney disease, diabetes mellitus, and hypertension. In blood vessels, VC is associated with major adverse cardiovascular events. Xanthohumol (XN), a main prenylated chalcone found in hops, has antioxidant effects to inhibit VC. This study aimed to investigate whether XN attenuates VC through in vivo study. A rat VC model was established by four weeks oral administration of vitamin D₃ plus nicotine in Sprague Dawley (SD) rats. In brief, 30 male SD rats were randomly divided into three groups: control, 25 mg/kg nicotine in 5 mL corn oil and 3 × 10⁵ IU/kg vitamin D₃ administration (VDN), and combination of VDN with 20 mg/L in 0.1% ethanol of XN (treatment group). Physiological variables such as body and heart weight and drinking consumption were weekly observed, and treatment with XN caused no differences among the groups. In comparison with the control group, calcium content and alkaline phosphatase (ALP) activity were increased in calcified arteries, and XN treatment reduced these levels. Dihydroethidium (DHE) and 2′,7′-dichloroflurescin diacetate (DCFH-DA) staining to identify Superoxide and reactive oxygen species generation from aorta tissue showed increased production in VDN group compared with the control and treatment groups. Hematoxylin eosin (HE) and Alizarin Red S staining were determined to show medial vascular thickness and calcification of vessel wall. Administration of VDN resulted in VC, and XN treatment showed improvement in vascular structure. Moreover, overexpression of osteogenic transcription factors bone morphogenetic protein 2 (BMP-2) and runt-related transcription factor 2 (Runx2) were significantly suppressed by XN treatment in VC. Moreover, downregulation of vascular phenotypic markers alpha-smooth muscle actin (α-SMA) and smooth muscle 22 alpha (SM22α) were increased by XN treatment in VC. Furthermore, XN treatment in VC upregulated nuclear translocation of nuclear factor-E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) expressions. Otherwise, Kelch-like ECH-associated protein 1 (Keap1) was alleviated by XN treatment in VC. In conclusion, our findings suggested that XN enhances antioxidant capacity to improve VC by regulating the Nrf2/Keap1/HO-1 pathway. Therefore, XN may have potential effects to decrease cardiovascular risk by reducing VC.

A novel murine model for assessing fetal and birth outcomes following transgestational maternal malaria infection

Plasmodium falciparum infection during pregnancy is a major cause of severe maternal illness and neonatal mortality. Mouse models are important for the study of gestational malaria pathogenesis. When infected with Plasmodium chabaudi chabaudi AS in early gestation, several inbred mouse strains abort at midgestation. We report here that outbred Swiss Webster mice infected with P. chabaudi chabaudi AS in early gestation carry their pregnancies to term despite high parasite burden and malarial hemozoin accumulation in the placenta at midgestation, with the latter associated with induction of heme oxygenase 1 expression. Infection yields reduced fetal weight and viability at term and a reduction in pup number at weaning, but does not influence postnatal growth prior to weaning. This novel model allows for the exploration of malaria infection throughout pregnancy, modeling chronic infections observed in pregnant women prior to the birth of underweight infants and enabling the production of progeny exposed to malaria in utero, which is critical for understanding the postnatal repercussions of gestational malaria. The use of outbred mice allows for the exploration of gestational malaria in a genetically diverse model system, better recapitulating the diversity of infection responses observed in human populations.

Testing an infection model to explain excess risk of preterm birth with long-term iron supplementation in a malaria endemic area

Background

In view of recent evidence from a randomized trial in Burkina Faso that periconceptional iron supplementation substantially increases risk of spontaneous preterm birth (< 37 weeks) in first pregnancies (adjusted relative risk = 2.22; 95% CI 1.39–3.61), explanation is required to understand potential mechanisms, including progesterone mediated responses, linking long-term iron supplementation, malaria and gestational age.

Methods

The analysis developed a model based on a dual hit inflammatory mechanism arising from simultaneous malaria and gut infections, supported in part by published trial results. This model is developed to understand mechanisms linking iron supplementation, malaria and gestational age. Background literature substantiates synergistic inflammatory effects of these infections where trial data is unavailable. A path modelling exercise assessed direct and indirect paths influencing preterm birth and gestation length.

Results

A dual hit hypothesis incorporates two main pathways for pro-inflammatory mechanisms, which in this model, interact to increase hepcidin expression. Trial data showed preterm birth was positively associated with C-reactive protein (P = 0.0038) an inflammatory biomarker. The malaria pathway upregulates C-reactive protein and serum hepcidin, thereby reducing iron absorption. The enteric pathway results from unabsorbed gut iron, which induces microbiome changes and pathogenic gut infections, initiating pro-inflammatory events with lipopolysaccharide expression. Data from the trial suggest that raised hepcidin concentration is a mediating catalyst, being inversely associated with shorter gestational age at delivery (P = 0.002) and positively with preterm incidence (P = 0.007). A segmented regression model identified a change-point consisting of two segments before and after a sharp rise in hepcidin concentration. This showed a post change hepcidin elevation in women with increasing C-reactive protein values in late gestation (post-change slope 0.55. 95% CI 0.39–0.92, P < 0.001). Path modelling confirmed seasonal malaria effects on preterm birth, with mediation through C-reactive protein and (non-linear) hepcidin induction.

Conclusions

Following long-term iron supplementation, dual inflammatory pathways that mediate hepcidin expression and culminate in progesterone withdrawal may account for the reduction in gestational age observed in first pregnancies in this area of high malaria exposure. If correct, this model strongly suggests that in such areas, effective infection control is required prior to iron supplementation to avoid increasing preterm births.

Trial registration NCT01210040. Registered with Clinicaltrials.gov on 27th September 2010

Activation of KEAP1/NRF2/P62 signaling alleviates high phosphate-induced calcification of vascular smooth muscle cells by suppressing reactive oxygen species production

Vascular calcification is a complication of diseases and conditions such as chronic kidney disease, diabetes, and aging. Previous studies have demonstrated that high concentrations of inorganic phosphate (Pi) can induce oxidative stress and vascular smooth muscle cell calcification. KEAP1 (Kelch-like ECH-associated protein 1)/NF-E2-related factor 2 (NRF2) signaling has been shown to play important roles in protecting cells from oxidative stress. The current study aims to investigate the possible involvement of the KEAP1/NRF2/P62 -mediated antioxidant pathway in vascular calcification induced by high Pi levels. Exposure of vascular smooth muscle cells (VSMCs) to high Pi concentrations promoted the accumulation of reactive oxygen species (ROS) and the nuclear translocation of NRF2, along with an increase in P62 levels and a decrease in KEAP1 levels. A classic NRF2 activator, tert-butylhydroquinone (tBHQ), significantly decreased ROS levels and calcium deposition in VSMCs by promoting the nuclear translocation of NRF2 and upregulating P62 and KEAP1 expression. In contrast, silencing NRF2 and P62 with siRNAs increased the levels of ROS and calcium deposition in VSMCs. In conclusion, VSMC calcification can be alleviated by the activation of the KEAP1/NRF2/P62 antioxidative pathway, which could have a protective role when it is exogenously activated by tBHQ.

Composition of the gut microbiota transcends genetic determinants of malaria infection severity and influences pregnancy outcome

BACKGROUND

Malaria infection in pregnancy is a major cause of maternal and foetal morbidity and mortality worldwide. Mouse models for gestational malaria allow for the exploration of the mechanisms linking maternal malaria infection and poor pregnancy outcomes in a tractable model system. The composition of the gut microbiota has been shown to influence susceptibility to malaria infection in inbred virgin mice. In this study, we explore the ability of the gut microbiota to modulate malaria infection severity in pregnant outbred Swiss Webster mice.

METHODS

In Swiss Webster mice, the composition of the gut microbiota was altered by disrupting the native gut microbes through broad-spectrum antibiotic treatment, followed by the administration of a faecal microbiota transplant derived from mice possessing gut microbes reported previously to confer susceptibility or resistance to malaria. Female mice were infected with P. chabaudi chabaudi AS in early gestation, and the progression of infection and pregnancy were tracked throughout gestation. To assess the impact of maternal infection on foetal outcomes, dams were sacrificed at term to assess foetal size and viability. Alternatively, pups were delivered by caesarean section and fostered to assess neonatal survival and pre-weaning growth in the absence of maternal morbidity. A group of dams was also euthanized at mid-gestation to assess infection and pregnancy outcomes.

FINDINGS

Susceptibility to infection varied significantly as a function of source of transplanted gut microbes. Parasite burden was negatively correlated with the abundance of five specific OTUs, including Akkermansia muciniphila and OTUs classified as Allobaculum, Lactobacillus, and S24-7 species. Reduced parasite burden was associated with reduced maternal morbidity and improved pregnancy outcomes. Pups produced by dams with high parasite burdens displayed a significant reduction in survival in the first days of life relative to those from malaria-resistant dams when placed with foster dams. At midgestation, plasma cytokine levels were similar across all groups, but expression of IFNγ in the conceptus was elevated in infected dams, and IL-10 only in susceptible dams. In the latter, transcriptional and microscopic evidence of monocytic infiltration was observed with high density infection; likewise, accumulation of malaria haemozoin was enhanced in this group. These responses, combined with reduced vascularization of the placenta in this group, may contribute to poor pregnancy outcomes. Thus, high maternal parasite burden and associated maternal responses, potentially dictated by the gut microbial community, negatively impacts term foetal health and survival in the early postnatal period.

INTERPRETATION

The composition of the gut microbiota in Plasmodium chabaudi chabaudi AS-infected pregnant Swiss Webster mice transcends the outbred genetics of the Swiss Webster mouse stock as a determinant of malaria infection severity, subsequently influencing pregnancy outcomes in malaria-exposed progeny. FUND: Research reported in this manuscript was supported by the University of Florida College of Veterinary Medicine (JMM, MM, and MG), the National Institute of Allergy and Infectious Diseases, the National Institute of Diabetes and Digestive and Kidney Diseases, and the Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health under award numbers T32AI060546 (to CDMS), R01HD46860 and R21AI111242 (to JMM), and R01 DK109560 (to MM). MG was supported by Department of Infectious Diseases and Immunology and University of Florida graduate assistantships. AA was supported by the 2017-2019 Peach State LSAMP Bridge to the Doctorate Program at the University of Georgia (National Science Foundation, Award # 1702361). The content is solely the responsibility of the authors and does not necessarily represent official views of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, the National Institute of Allergy and Infectious Diseases, the National Institute of Diabetes and Digestive and Kidney Diseases, or the National Institutes of Health.

Integrated Proteomics Reveals Apoptosis-related Mechanisms Associated with Placental Malaria

Malaria in pregnancy is a public health concern in malaria-endemic areas. Accumulation of maternal immune cells in the placenta and increased levels of inflammatory cytokines caused by sequestration of Plasmodium falciparum-infected erythrocytes have been associated to poor neonatal outcomes, including low birth weight because of fetal growth restriction. Little is known about the molecular changes occurring in a P. falciparum-infected placenta that has developed placental malaria during pregnancy but had the parasites cleared by pharmacological treatment (past infection). We conducted an integrated proteome, phosphoproteome and glycoproteome analysis in past P. falciparum-infected placentas aiming to find molecular changes associated with placental malaria. A total of 2946 proteins, 1733 N-linked glycosites and 4100 phosphosites were identified and quantified in this study, disclosing overrepresented processes related to oxidative stress, protein folding and regulation of apoptosis in past-infected placentas Moreover, AKT and ERK signaling pathways activation, together with clinical data, were further correlated to an increased apoptosis in past-infected placentas. This study showed apoptosis-related mechanisms associated with placental malaria that can be further explored as therapeutic target against adverse pregnancy outcomes.

CD39 and CD73 activity are protective in a mouse model of antiphospholipid antibody-induced miscarriages

OBJECTIVE

Antiphospholipid syndrome (APS) is a systemic autoimmune disorder of young adults associated with devastating pregnancy complications (recurrent miscarriages, preeclampsia and low birth weight) and vascular complications including thrombosis. The key components implicated in pathogenesis of APS are the complement cascade and tissue factor (TF) activity causing inflammation and coagulation. Purinergic signalling involving catabolism of ATP to adenosine by cell-surface enzymes CD39 and CD73 has anti-inflammatory and anti-thrombotic effects. We studied whether activities of CD39 and CD73 are important in preventing the development of miscarriages in APS.

METHODS

We studied frequency of miscarriages and decidual pathology following passive transfer of human aPL-ab to pregnant wildtype mice, and mice deficient in CD39 and CD73, and also transgenic mice exhibiting 2-3X higher CD39 activity.

RESULTS

aPL-ab infusion in pregnant CD39-or CD73-knockout mice triggers an increase in miscarriages, associated with increased TF expression and complement deposition as well as elevated oxidative stress and pro-inflammatory TNF-α and IL-10 expression within the placental decidua. In contrast, aPL-ab induced miscarriages are prevented in mice over-expressing CD39, with reduced decidual TF expression and C3d deposition, diminished lipid peroxidation (4-hydroxynonenal or 4-HNE positive lipid adducts), and reduced TNF-α expression.

CONCLUSION

We demonstrate a protective role for CD39 in APS and provide rationale for both the development of endothelial cell-targeted soluble CD39 as a novel therapeutic for APS and analysis of perturbations in the purinergic pathway to explain human disease.