A Stillborn Multiple Organs' Investigation from a Maternal DENV-4 Infection: Histopathological and Inflammatory Mediators Characterization

First clinical reports of acute hantavirus and dengue infections among pregnant women in the Caribbean

BACKGROUND

Hantavirus and dengue virus infections lead to diseases causing economic and public health concerns. Acute hantavirus infections can lead to similar clinical haemorrhagic signs as other endemic diseases including dengue and leptospirosis.

METHODS

Using a retrospective case analysis of pregnant dengue and hantavirus disease patients with clinical reports and compatible clinical laboratory information during pregnancy, we report the first evidence of dengue and hantavirus infections and a case of dual dengue and hantavirus infection among pregnant women in the Caribbean. Laboratory testing by enzyme-linked immunosorbent assay (ELISA) and non-structural protein 1 (NS1) for DENV and for hantavirus infection pseudotype focus reduction neutralisation tests (pFRNT), ELISA and immunochromatographic (ICG) strips.

RESULTS

Four pregnant cases with acute DENV infections were identified; however, only one out of the four cases (25%) had a detailed medical record to permit abstraction of clinical data. Six hantavirus infected pregnant cases were identified with gestation periods ranged from 36 to 39 weeks; none of the reported patients exhibited previous pregnancy complications prior to hospitalisation and infection. Acute liver damage was observed in three of the six cases (AST readings) who were subsequently diagnosed with hepatitis in pregnancy and variable clinical outcomes were observed with term and pre-term deliveries.

CONCLUSIONS

Whilst hantavirus infection in pregnancy is rare, consideration should be given to differential diagnosis with fever, kidney involvement, liver involvement, haemorrhagic symptoms and thrombocytopenia in endemic areas with clinically similar diseases such as dengue and leptospirosis.HighlightsFirst recorded case of hantavirus and dengue co-infection in a pregnant woman.First detailed report of clinical hantavirus infection in pregnant women in the Caribbean.First published report of clinical dengue infection in pregnant woman in the Caribbean.Possible complications of pregnancy following hantavirus infection.Pre-term birth and low birth weights.Clinical course of hantavirus infection in a Caribbean population.

Dengue Vaccination: Towards a New Dawn of Curbing Dengue Infection

Dengue is an infectious disease caused by dengue virus (DENV) and is a serious global burden. Antibody-dependent enhancement and the ability of DENV to infect immune cells, along with other factors, lead to fatal Dengue Haemorrhagic Fever and Dengue Shock Syndrome. This necessitates the development of a robust and efficient vaccine but vaccine development faces a number of hurdles. In this review, we look at the epidemiology, genome structure and cellular targets of DENV and elaborate upon the immune responses generated by human immune system against DENV infection. The review further sheds light on various challenges in development of a potent vaccine against DENV which is followed by presenting a current account of different vaccines which are being developed or have been licensed.

Common pathways targeted by viral hemorrhagic fever viruses to infect the placenta and increase the risk of stillbirth

Viral hemorrhagic fevers (VHF) are endemic to Africa, South America and Asia and contribute to significant maternal and fetal morbidity and mortality. Viruses causing VHFs are typically zoonotic, spreading to humans through livestock, wildlife, or mosquito vectors. Some of the most lethal VHF viruses also impart a high-risk of stillbirth including ebolaviruses, Marburg virus (MARV), Lassa virus (LASV), and Rift Valley Fever Virus (RVFV). Large outbreaks and epidemics are common, though the impact on the mother, fetus and placenta is understudied from a public health, clinical and basic science perspective. Notably, these viruses utilize ubiquitous cellular surface entry receptors critical for normal placental function to enable viral invasion into multiple key cell types of the placenta and set the stage for maternal-fetal transmission and stillbirth. We employ insights from molecular virology and viral immunology to discuss how trophoblast expression of viral entry receptors for VHF viruses may increase the risk for viral transmission to the fetus and stillbirth. As the frequency of VHF outbreaks is expected to increase with worsening climate change, understanding the pathogenesis of VHF-related diseases in the placenta is paramount to predicting the impact of emerging viruses on the placenta and perinatal outcomes.

The Innate Immune Response in DENV- and CHIKV-Infected Placentas and the Consequences for the Fetuses: A Minireview

Dengue virus (DENV) and chikungunya (CHIKV) are arthropod-borne viruses belonging to the Flaviviridae and Togaviridae families, respectively. Infection by both viruses can lead to a mild indistinct fever or even lead to more severe forms of the diseases, which are characterized by a generalized inflammatory state and multiorgan involvement. Infected mothers are considered a high-risk group due to their immunosuppressed state and the possibility of vertical transmission. Thereby, infection by arboviruses during pregnancy portrays a major public health concern, especially in countries where epidemics of both diseases are regular and public health policies are left aside. Placental involvement during both infections has been already described and the presence of either DENV or CHIKV has been observed in constituent cells of the placenta. In spite of that, there is little knowledge regarding the intrinsic earlier immunological mechanisms that are developed by placental cells in response to infection by both arboviruses. Here, we approach some of the current information available in the literature about the exacerbated presence of cells involved in the innate immune defense of the placenta during DENV and CHIKV infections.

Neutrophil infiltration leads to fetal growth restriction by impairing the placental vasculature in DENV-infected pregnant mice

BACKGROUND

Dengue virus (DENV) infection during pregnancy increases the risk of adverse fetal outcomes, which has become a new clinical challenge. However, the underlying mechanism remains unknown.

METHODS

The effect of DENV-2 infection on fetuses was investigated using pregnant interferon α/β receptor-deficient (Ifnar1-/-) mice. The histopathological changes in the placentas were analyzed by morphological techniques. A mouse inflammation array was used to detect the cytokine and chemokine profiles in the serum and placenta. The infiltration characteristics of inflammatory cells in the placentas were evaluated by single-cell RNA sequencing.

FINDINGS

Fetal growth restriction observed in DENV-2 infection was mainly caused by the destruction of the placental vasculature rather than direct damage from the virus in our mouse model. After infection, neutrophil infiltration into the placenta disrupts the expression profile of matrix metalloproteinases, which leads to placental dysvascularization and insufficiency. Notably, similar histopathological changes were observed in the placentas from DENV-infected puerperae.

INTERPRETATION

Neutrophils play key roles in placental histopathological damage during DENV infection, which indicates that interfering with aberrant neutrophil infiltration into the placenta may be an important therapeutic target for adverse pregnancy outcomes in DENV infection.

FUNDING

The National Key Research and Development Plans of China (2021YFC2300200-02 to J.A., 2019YFC0121905 to Q.Z.C.), the National Natural Science Foundation of China (NSFC) (U1902210 and 81972979 to J. A., 81902048 to Z. Y. S., and 82172266 to P.G.W.), and the Support Project of High-level Teachers in Beijing Municipal Universities in the Period of 13th Five-year Plan, China (IDHT20190510 to J. A.).

Liver immunopathogenesis in fatal cases of dengue in children: detection of viral antigen, cytokine profile and inflammatory mediators

Introduction

Dengue virus (DENV), the etiologic agent of dengue fever illness, represents a global public health concern, mainly in tropical and subtropical areas across the globe. It is well known that this acute viral disease can progress to severe hemorrhagic stages in some individuals, however, the immunopathogenic basis of the development of more severe forms by these patients is yet to be fully understood.

Objective

In this context, we investigated and characterized the histopathological features as well as the cytokine profile and cell subpopulations present in liver tissues from three fatal cases of DENV in children.

Methods

Hematoxylin and Eosin, Periodic Acid Schiff and Picro Sirius Red staining were utilized for the histopathological analysis. Immunohistochemistry assay was performed to characterize the inflammatory response and cell expression patterns.

Results

Vascular dysfunctions such as hemorrhage, vascular congestion and edema associated with a mononuclear infiltrate were observedin all three cases. Liver tissues exhibited increased presence of CD68+ and TCD8+ cells as well as high expression of MMP-9, TNF-a, RANTES, VEGFR-2 mediators. Viral replication was confirmed by the detection of NS3 protein.

Conclusion

Taken together, these results evidenced key factors that may be involved in the development of severe alterations in liver tissues of children in response to DENV infection.

Arthropod-Borne Flaviviruses in Pregnancy

Flaviviruses are a diverse group of enveloped RNA viruses that cause significant clinical manifestations in the pregnancy and postpartum periods. This review highlights the epidemiology, pathophysiology, clinical features, diagnosis, and prevention of the key arthropod-borne flaviviruses of concern in pregnancy and the neonatal period-Zika, Dengue, Japanese encephalitis, West Nile, and Yellow fever viruses. Increased disease severity during pregnancy, risk of congenital malformations, and manifestations of postnatal infection vary widely amongst this virus family and may be quite marked. Laboratory confirmation of infection is complex, especially due to the reliance on serology for which flavivirus cross-reactivity challenges diagnostic specificity. As such, a thorough clinical history including relevant geographic exposures and prior vaccinations is paramount for accurate diagnosis. Novel vaccines are eagerly anticipated to ameliorate the impact of these flaviviruses, particularly neuroinvasive disease manifestations and congenital infection, with consideration of vaccine safety in pregnant women and children pivotal. Moving forward, the geographical spread of flaviviruses, as for other zoonoses, will be heavily influenced by climate change due to the potential expansion of vector and reservoir host habitats. Ongoing 'One Health' engagement across the human-animal-environment interface is critical to detect and responding to emergent flavivirus epidemics.

Clinical and experimental evidence for transplacental vertical transmission of flaviviruses

The Zika virus (ZIKV) epidemic outbreak in Americas in 2016 attracted global attention because of the association of the virus infection with severe birth defects such as microcephaly, mediated through transplacental virus transmission during pregnancy. Less well-known, but also reported is the increasing evidence that prenatal vertical transmission can be caused by other flaviviruses such as dengue virus (DENV). Currently, the mechanism(s) that cause the vertical transmission of flaviviruses is understudied. Here we review the published reports of clinical evidence of intrauterine transmission of ZIKV and other flaviviruses. We also discuss the animal models for flavivirus infection during pregnancy that have been developed to study the mechanisms underlying the transplacental transmission of flaviviruses in order to develop potential countermeasures for its prevention.

Associations of circulation levels of cytokines with birthweight, preterm birth, spontaneous miscarriages, and stillbirth: A Mendelian randomization analysis

Background: The association between immune imbalances and adverse pregnancy outcomes has been extensive investigated by observational studies, but remain unclear. Thus, this study aimed to establish the causality of the circulation levels of cytokines on adverse pregnancy outcomes, such as offspring's birthweight (BW), preterm birth (PTB), spontaneous miscarriage (SM), and stillbirth (SB). Methods: Two-sample Mendelian randomization (MR) analysis was employed to investigate potential causal relations between 41 cytokines and pregnancy outcomes on the basis of previously published GWAS datasets. Multivariable MR (MVMR) analysis was implemented to investigate the effect of the composition of cytokine networks on the pregnancy outcomes. Potential risk factors were further estimated to explore the potential mediators. Results: Genetic correlation analysis based on large GWAS data sources revealed that genetically predicted MIP1b (β = -0.027, S.E. = 0.010, p = 0.009) and MCSF (β = -0.024, S.E. = 0.011, p = 0.029) were associated with reduced offspring's BW, MCP1 (OR: 0.90, 95% CI: 0.83-0.97, p = 0.007) was associated with reduced SM risk, SCF (β = -0.014, S.E. = 0.005, p = 0.012) associated with decreased number of SB in MVMR. The univariable MR showed that GROa (OR: 0.92, 95% CI: 0.87-0.97, p = 0.004) was associated with decreased PTB risk. Except for the MCSF-BW association, all above associations surpassed the Bonferroni corrected threshold. The MVMR results revealed that MIF, SDF1a, MIP1b, MCSF and IP10 composed cytokine networks, associated with offspring's BW. Risk factors analysis indicated that the above causal associations might be mediated by smoking behaviors. Conclusion: These findings suggest the causal associations of several cytokines with adverse pregnancy outcomes, which were potentially mediated by smoking and obesity. Some of the results did not been corrected through multiple tests and larger samples verification is required in further studies.

Immunopathology of Renal Tissue in Fatal Cases of Dengue in Children

Dengue virus (DENV) infection represents a worldwide public health concern and can cause damage to multiple organs, including the kidney. In this work, we investigated the histopathological changes caused by dengue virus infection along with the detection of inflammatory mediators, cytokines, and cell expression patterns in the renal tissue of three fatal cases in children. Hematoxylin and Eosin staining was performed to analyze these histopathological changes. Immunohistochemistry allowed for the detection of immunological inflammatory markers in renal tissues that were quantified and further analyzed. Vascular congestion, edema and glomerular infiltrate were observed in the three cases, in addition to the thickening of the matrix area around the glomerular capillaries and mononuclear infiltrate associated with vascular congestion in the medullary region. The renal tissues exhibited collagen deposition and high expression of CD68⁺ Mø, CD8⁺ T, CD56⁺ cells and MMP-9, and the cytokine profile was mainly characterized by the expression of IFN-γ and TNF-α. Additionally, the expression of RANTES, VEGFR-2 and VCAM-1 were observed. The replication of DENV was evidenced by the detection of the NS3 protein. These results contributed to clarifying the main factors that may be involved in changes in the renal tissue of fatal cases of dengue in children.

Histopathological and immunological characteristics of placentas infected with chikungunya virus

Although vertical transmission of CHIKV has been reported, little is known about the role of placenta in the transmission of this virus and the effects of infection on the maternal-fetal interface. In this work we investigated five placentas from pregnant women who became infected during the gestational period. Four formalin-fixed paraffin-embedded samples of placenta (cases 1-4) were positive for CHIKV by RT-PCR. One (case 5) had no positive test of placenta, but had positive RT-PCR for CHIKV in the serum of the mother and the baby, confirming vertical transmission. The placentas were analyzed regarding histopathological and immunological aspects. The main histopathological changes were: deciduitis, villous edema, deposits, villous necrosis, dystrophic calcification, thrombosis and stem vessel obliteration. In infected placentas we noted increase of cells (CD8+ and CD163+) and pro- (IFN-γ and TNF-α) and anti-inflammatory (TGF-β and IL-10) cytokines compared to control placentas. Moreover, CHIKV antigen was detected in decidual cell, trophoblastic cells, stroma villi, Hofbauer cells, and endothelial cells. In conclusion, CHIKV infection seems to disrupt placental homeostasis leading to histopathological alterations in addition to increase in cellularity and cytokines overproduction, evidencing an altered and harmful environment to the pregnant woman and fetus.

Placental Alterations in a Chikungunya-Virus-Infected Pregnant Woman: A Case Report

Chikungunya virus (CHIKV) is an arthropod-borne virus first isolated in Tanzania, Africa. The virus has spread to Asia as well as South and Central America through infected Aedes mosquitoes. Vertical transmission may also occur, and was first documented during a chikungunya outbreak in La Réunion Island in 2005. Since then, some authors have been discussing the role of the placenta in maternal–fetal CHIKV transmission. CHIKV infection is characterized by fever, headache, rash, and arthralgia. However, atypical manifestations and clinical complications, including neurological, cardiac, renal, ocular, and dermal, may occur in some cases. In this report, we describe the case of a pregnant woman infected by CHIKV during the third trimester of gestation, who presented with severe dermatological manifestations during the epidemic in Rio de Janeiro, Brazil in 2019. CHIKV RNA and antigens were detected in the placental tissue, which presented with histopathological (deciduitis, fibrin deposition, edema, fetal vessel thickening, and chorioamnionitis) and ultrastructural alterations (cytotrophoblast with mitochondrial swelling and dilated cisterns in endoplasmic reticulum, vesicles in syncytiotrophoblasts, and thickening of the basement membrane of the endothelium).

Experimental evidence for a high rate of maternal-fetal transmission of dengue virus in the presence of antibodies in immunocompromised mice

Background

Congenital disorders associated with prenatal vertical transmission of Zika virus (ZIKV) is well established since the 2016 outbreak in the Americas. However, despite clinical reports of similar mode of transmission for other flaviviruses such as dengue virus (DENV), the phenomenon has not been experimentally explored.

Methods

Pregnant AG129 mice were infected with DENV1 in the presence or absence of enhancing antibodies at different gestational time points. ZIKV was used for comparison. We quantified viral load in fetus and placentas and performed comprehensive gene expression profiling in the maternal (decidua) and fetal portion of placenta separately.

Findings

We demonstrate in a laboratory experimental setting that DENV can be transmitted vertically in a gestation stage-dependent manner similar to ZIKV, and this incidence drastically increases in the presence of enhancing antibodies. Interestingly, a high rate of DENV fetal infection occurs even though the placental viral load is significantly lower than that found in ZIKV-infected dams. Comprehensive gene expression profiling revealed DENV infection modulates a variety of inflammation-associated genes comparable to ZIKV in decidua and fetal placenta in early pregnancy.

Interpretation

Our findings suggest that the virus-induced modulation of host gene expression may facilitate DENV to cross the placental barrier in spite of lower viral burden compared to ZIKV. This mouse model may serve to identify the host determinants required for the vertical transmission of flaviviruses and develop appropriate countermeasures.

Funding

National Medical Research Council/Open Fund Individual Research Grant MOH-000524 (SW), MOH-000086 and OFIRG20nov-0017 (SGV).

Placental Macrophage (Hofbauer Cell) Responses to Infection During Pregnancy: A Systematic Scoping Review

BACKGROUND

Congenital infection of the fetus via trans-placental passage of pathogens can result in severe morbidity and mortality. Even without transmission to the fetus, infection of the placenta itself is associated with pregnancy complications including pregnancy loss and preterm birth. Placental macrophages, also termed Hofbauer cells (HBCs), are fetal-origin macrophages residing in the placenta that are likely involved in responding to placental infection and protection of the developing fetus. As HBCs are the only immune cell present in the villous placenta, they represent one of the final opportunities for control of infection and prevention of passage to the developing fetus.

OBJECTIVE AND RATIONALE

The objective of this review was to provide a systematic overview of the literature regarding HBC responses during infection in pregnancy, including responses to viral, bacterial, and parasitic pathogens.

METHODS

PubMed and Scopus were searched on May 20th, 2021, with no limit on publication date, to identify all papers that have studied placental macrophages/Hofbauer cells in the context of infection. The following search strategy was utilized: (hofbauer* OR "hofbauer cells" OR "hofbauer cell" OR "placental macrophage" OR "placental macrophages") AND [infect* OR virus OR viral OR bacteri* OR parasite* OR pathogen* OR LPS OR "poly(i:c)" OR toxoplasm* OR microb* OR HIV)].

OUTCOMES

86 studies were identified for review. This included those that investigated HBCs in placentas from pregnancies complicated by maternal infection and in vitro studies investigating HBC responses to pathogens or Pathogen-Associated Molecular Patterns (PAMPs). HBCs can be infected by a variety of pathogens, and HBC hyperplasia was a common observation. HBCs respond to pathogen infection and PAMPs by altering their transcriptional, translational and secretion profiles. Co-culture investigations demonstrate that they can replicate and transmit pathogens to other cells. In other cases, they may eliminate the pathogen through a variety of mechanisms including phagocytosis, cytokine-mediated pathogen elimination, release of macrophage extracellular traps and HBC-antibody-mediated neutralization. HBC responses differ across gestation and may be influenced by pre-existing immunity. Clinical information, including gestational age at infection, gestational age of the samples, mode of sample collection and pregnancy outcome were missing for the majority of studies.

Tenovin-1 inhibited dengue virus replication through SIRT2

Dengue fever is a common arbovirus disease, which has been spread to the entire tropical world. At present, effective drugs for the treatment of dengue fever have not yet appeared, and the dengue vaccines studied in various countries have also experienced severe adverse reactions. Thus it is urgent to find new chemicals against dengue virus. Now we found Sirtuins (SIRTs) were increased during dengue virus infection and tenovin-1, a SIRT1/2 inhibitor, showed an impressive antiviral ability in vitro. In BHK-21 cells, tenovin-1 inhibited the replication of DENV2 with an EC50 at 3.41 ± 1.10 μM, also inhibited other three types of dengue viruses with EC50 at 0.97 ± 1.11 μM, 1.81 ± 1.08 μM, 3.81 ± 1.34 μM respectively. Moreover, the cytopathic effect-induced DENV2 was largely improved by tenovin-1 treatment and the release of progeny viruses was inhibited by tenovin-1 treatment. At the same time, the viral protein level and mRNA level were decreased with tenovin-1 treatment after dengue virus infection. From the drug-addition assay, the tenovin-1 played its antiviral after viral infection, which indicated tenovin-1 was not a microbicide. Apart from its antiviral effect, tenovin-1 inhibited the inflammatory response caused by DENV2, reducing the release of inflammatory factors during viral infection. The antiviral effect of tenovin-1 was abrogated with SIRT agonist or SIRT2 knockdown treatment, which indicated the effect of tenovin-1 was on-target. In conclusion, tenovin-1 was proved to be a promising compound against flavivirus infection through SIRT2, which should be pay more attention for further study.

Neonatal Outcomes From Arboviruses in the Perinatal Period: A State-of-the-Art Review

Since the 2016 Zika outbreak and the understanding of the teratogenic effect of this infection, there has been a newfound interest in arbovirus infections and their effects on pregnancy, resulting in numerous publications in the last 5 years. However, limited literature focuses on arbovirus infection in different stages of pregnancy and their effect on the neonate. There is currently no consensus management of perinatal acquisition of arboviruses, and current evidence is largely anecdotal observational reports. Teratogens can have different effects on the developing fetus depending on the time of infection, so infections during pregnancy should be analyzed by trimester. A better understanding of arbovirus infection in the perinatal period is required to assist obstetric, neonatal, and pediatric clinicians in making decisions about the management of mother and neonate. Our objective was to assess the evidence of adverse neonatal outcomes for several arboviral infections when contracted during the perinatal period to guide clinicians in managing these patients. There are 8 arboviruses for which neonatal outcomes from maternal acquisition in the perinatal period have been reported, with the most data for dengue and Chikungunya virus infections. The evidence reviewed in this article supports the adoption of preventive strategies to avoid ticks and mosquitoes close to the date of delivery. For the other arbovirus infections, further community-based cohort studies during outbreaks are required to evaluate whether these infections have a similar teratogenic impact.

Spontaneous Abortion and Chikungunya Infection: Pathological Findings

Intrauterine transmission of the Chikungunya virus (CHIKV) during early pregnancy has rarely been reported, although vertical transmission has been observed in newborns. Here, we report four cases of spontaneous abortion in women who became infected with CHIKV between the 11th and 17th weeks of pregnancy. Laboratorial confirmation of the infection was conducted by RT-PCR on a urine sample for one case, and the other three were by detection of IgM anti-CHIKV antibodies. Hematoxylin and eosin (H&E) staining and an electron microscopy assay allowed us to find histopathological, such as inflammatory infiltrate in the decidua and chorionic villi, as well as areas of calcification, edema and the deposition of fibrinoid material, and ultrastructural changes, such as mitochondria with fewer cristae and ruptured membranes, endoplasmic reticulum with dilated cisterns, dispersed chromatin in the nuclei and the presence of an apoptotic body in case 1. In addition, by immunohistochemistry (IHC), we found a positivity for the anti-CHIKV antibody in cells of the endometrial glands, decidual cells, syncytiotrophoblasts, cytotrophoblasts, Hofbauer cells and decidual macrophages. Electron microscopy also helped in identifying virus-like particles in the aborted material with a diameter of 40–50 nm, which was consistent with the size of CHIKV particles in the literature. Our findings in this study suggest early maternal fetal transmission, adding more evidence on the role of CHIKV in fetal death.

The limited knowledge of placental damage due to neglected infections: ongoing problems in Latin America

The placenta works as a selective barrier, protecting the fetus from potential infections that may affect the maternal organism during pregnancy. In this review, we will discuss several challenging infections that are common within Latin American countries and that may affect the maternal-fetal interface and pose risks to fetal development. Specifically, we will focus on emerging infectious diseases including the arboviruses, malaria, leishmaniasis, and the bacterial foodborne disease caused by Shiga toxin-producing Escherichia coli. We will also highlight some topics of interest currently being studied by research groups that comprise an international effort aimed at filling the knowledge gaps in this field. These topics address the relationship between exposure to microorganisms and placental abnormalities, congenital anomalies, and complications of pregnancy.

ABBREVIATIONS

ADE: antibody-dependent enhancement; CCL2: monocyte chemoattractant protein-1; CCL3: macrophage inflammatory protein-1 α; CCL5: chemokine (C-C motif) ligand 5; CHIKV: chikungunya virus; DCL: diffuse cutaneous leishmaniasis; DENV: dengue virus; Gb3: glycolipid globotriaosylceramyde; HIF: hypoxia-inducible factor; HUS: hemolytic uremic syndrome; IFN: interferon; Ig: immunoglobulins; IL: interleukin; IUGR: intrauterine growth restriction; LCL: localized cutaneous leishmaniasis; LPS: lipopolysaccharid; MCL: mucocutaneous leishmaniasis; NO: nitric oxide; PCR: polymerase chain reaction; PGF: placental growth factor; PM: placental malaria; RIVATREM: Red Iberoamericana de Alteraciones Vasculares em transtornos del Embarazo; sVEGFR: soluble vascular endothelial growth factor receptor; STEC: shiga toxin-producing Escherichia coli; stx: shiga toxin protein; TNF: tumor necrosis factor; TOAS: T cell original antigenic sin; Var2CSA: variant surface antigen 2-CSA; VEGF: vascular endothelial growth factor; VL: visceral leishmaniasis; WHO: world health organization; YFV: yellow fever virus; ZIKV: Zika virus.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and glial cells: Insights and perspectives

In December 2019, a pneumonia outbreak was reported in Wuhan, Hubei province, China. Since then, the World Health Organization declared a public health emergency of international concern due to a growing number of deaths around the globe, as well as unparalleled economic and sociodemographic consequences. The disease called coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel form of human coronavirus. Although coronavirus infections have been associated with neurological manifestations such as febrile seizures, convulsions, change in mental status, and encephalitis, less is known about the impact of SARS-CoV-2 in the brain. Recently, emerging evidence suggests that SARS-CoV-2 is associated with neurological alterations in COVID-19 patients with severe clinical manifestations. The molecular and cellular mechanisms involved in this process, as well as the neurotropic and neuroinvasive properties of SARS-CoV-2, are still poorly understood. Glial cells, such as astrocytes and microglia, play pivotal roles in the brain response to neuroinflammatory insults and neurodegenerative diseases. Further, accumulating evidence has shown that those cells are targets of several neurotropic viruses that severely impact their function. Glial cell dysfunctions have been associated with several neuroinflammatory diseases, suggesting that SARS-CoV-2 likely has a primary effect on these cells in addition to a secondary effect from neuronal damage. Here, we provide an overview of these data and discuss the possible implications of glial cells as targets of SARS-CoV-2. Considering the roles of microglia and astrocytes in brain inflammatory responses, we shed light on glial cells as possible drivers and potential targets of therapeutic strategies against neurological manifestations in patients with COVID-19. The main goal of this review is to highlight the need to consider glial involvement in the progression of COVID-19 and potentially include astrocytes and microglia as mediators of SARS-CoV-2-induced neurological damage.

Changing the paradigm of IFN-γ at the interface between innate and adaptive immunity: Macrophage-derived IFN-γ

IFN-γ plays a critical role in the immune response to bacterial infections. It is established that IFN-γ is mainly produced by NK/ILC1 cells and T cells, and most of papers have rejected the biologic reality of alternative sources for more than 20 years. Here, we are proposing to revisit this dogma and discuss the role of macrophage-derived IFN-γ in bacterial infections. Our hypothesis is based on a panel of publications and is recently revived by our results on placenta, a chimeric organ in which the immune response is tailored to protect the fetus from mother's immune response. The culture of purified placental macrophages is associated with a production of IFN-γ that may contribute to fetal protection from bacterial infections before eliciting a Th1-like immune response potentially pathogenic for pregnancy. Hence, macrophage IFN-γ may be a novel actor of early crosstalk between innate and adaptive immunity in the context of host defense against bacterial infections.

Embryotoxic impact of Zika virus in a rhesus macaque in vitro implantation model†

Zika virus (ZIKV) infection is associated with adverse pregnancy outcomes in humans, and infection in the first trimester can lead to miscarriage and stillbirth. Vertical and sexual transmissions of ZIKV have been demonstrated, yet the impact of infection during the initial stages of pregnancy remains unexplored. Here we defined the impact of ZIKV on early embryonic and placental development with a rhesus macaque model. During in vitro fertilization (IVF), macaque gametes were inoculated with a physiologically relevant dose of 5.48log10 plaque-forming units (PFU) of Zika virus/H.sapiens-tc/PUR/2015/PRVABC59_v3c2. Exposure at fertilization did not alter blastocyst formation rates compared to controls. To determine the impact of ZIKV exposure at implantation, hatched blastocysts were incubated with 3.26log10, 4.26log10, or 5.26log10 PFU, or not exposed to ZIKV, followed by extended embryo culture for 10 days. ZIKV exposure negatively impacted attachment, growth, and survival in comparison to controls, with exposure to 5.26log10 PFU ZIKV resulting in embryonic degeneration by day 2. Embryonic secretion of pregnancy hormones was lower in ZIKV-exposed embryos. Increasing levels of infectious virus were detected in the culture media post-exposure, suggesting that the trophectoderm is susceptible to productive ZIKV infection. These results demonstrate that ZIKV exposure severely impacts the zona-free blastocyst, whereas exposure at the time of fertilization does not hinder blastocyst formation. Overall, early stages of pregnancy may be profoundly sensitive to infection and pregnancy loss, and the negative impact of ZIKV infection on pregnancy outcomes may be underestimated.