Specific stimulation of HIV-1 replication in human placental trophoblasts by an antigen of Plasmodium falciparum

Protozoan co-infections and parasite influence on the efficacy of vaccines against bacterial and viral pathogens

A wide range of protozoan pathogens either transmitted by vectors (Plasmodium, Babesia, Leishmania and Trypanosoma), by contaminated food or water (Entamoeba and Giardia), or by sexual contact (Trichomonas) invade various organs in the body and cause prominent human diseases, such as malaria, babesiosis, leishmaniasis, trypanosomiasis, diarrhea, and trichomoniasis. Humans are frequently exposed to multiple pathogens simultaneously, or sequentially in the high-incidence regions to result in co-infections. Consequently, synergistic or antagonistic pathogenic effects could occur between microbes that also influences overall host responses and severity of diseases. The co-infecting organisms can also follow independent trajectory. In either case, co-infections change host and pathogen metabolic microenvironments, compromise the host immune status, and affect microbial pathogenicity to influence tissue colonization. Immunomodulation by protozoa often adversely affects cellular and humoral immune responses against co-infecting bacterial pathogens and promotes bacterial persistence, and result in more severe disease symptoms. Although co-infections by protozoa and viruses also occur in humans, extensive studies are not yet conducted probably because of limited animal model systems available that can be used for both groups of pathogens. Immunosuppressive effects of protozoan infections can also attenuate vaccines efficacy, weaken immunological memory development, and thus attenuate protection against co-infecting pathogens. Due to increasing occurrence of parasitic infections, roles of acute to chronic protozoan infection on immunological changes need extensive investigations to improve understanding of the mechanistic details of specific immune responses alteration. In fact, this phenomenon should be seriously considered as one cause of breakthrough infections after vaccination against both bacterial and viral pathogens, and for the emergence of drug-resistant bacterial strains. Such studies would facilitate development and implementation of effective vaccination and treatment regimens to prevent or significantly reduce breakthrough infections.

Subsequent malaria enhances virus-specific T cell immunity in SIV-infected Chinese rhesus macaques

Background

Coinfection with HIV and Plasmodium parasites is fairly common, but the sequence of infection with these two pathogens and their impact on disease progression are poorly understood.

Methods

A Chinese rhesus macaque HIV and Plasmodium coinfection model was established to compare the impact of pre-existing and subsequent malaria on the progression of SIV infection.

Results

We found that a pre-existing malaria caused animals to produce a greater number of CD4⁺CCR5⁺ T cells for SIV replication, resulting in higher viral loads. Conversely, subsequent malaria induced a substantially larger proportion of CD4⁺CD28^highCD95^high central memory T cells and a stronger SIV-specific T cell response, maintained the repertoire diversity of SIV-specific T cell receptors, and generated new SIV-specific T cell clonotypes to trace SIV antigenic variation, resulting in improved survival of SIV-infected animals.

Conclusion

The complex outcomes of this study may have important implications for research on human HIV and malaria coinfection. The infection order of the two pathogens (HIV and malaria parasites) should be emphasized.

Understanding Viral and Immune Interplay During Vertical Transmission of HIV: Implications for Cure

Despite the significant progress that has been made to eliminate vertical HIV infection, more than 150,000 children were infected with HIV in 2019, emphasizing the continued need for sustainable HIV treatment strategies and ideally a cure for children. Mother-to-child-transmission (MTCT) remains the most important route of pediatric HIV acquisition and, in absence of prevention measures, transmission rates range from 15% to 45% via three distinct routes: in utero, intrapartum, and in the postnatal period through breastfeeding. The exact mechanisms and biological basis of these different routes of transmission are not yet fully understood. Some infants escape infection despite significant virus exposure, while others do not, suggesting possible maternal or fetal immune protective factors including the presence of HIV-specific antibodies. Here we summarize the unique aspects of HIV MTCT including the immunopathogenesis of the different routes of transmission, and how transmission in the antenatal or postnatal periods may affect early life immune responses and HIV persistence. A more refined understanding of the complex interaction between viral, maternal, and fetal/infant factors may enhance the pursuit of strategies to achieve an HIV cure for pediatric populations.

Relationship between placenta malaria and mother to child transmission of HIV infection in pregnant women in South East Nigeria

Background

This study determined the rate of mother-to-child transmission (MTCT) of HIV among HIV positive women with placenta malaria and factors associated with placenta malaria.

Methods

This was a prospective observational study of booked HIV positive pregnant women in labour. A smear for malaria parasite was made from blood taken from the placental tissue post-delivery. The baby HIV testing was done with DNA polymerase chain reaction at 6 weeks postpartum. Data on age, parity, gestational age, religion, address, highest educational attainment and knowledge about malaria prevention in pregnancy was obtained with questionnaires and analysed using SPSS version 20. The P-value was set at 0.05 providing a confidence interval of 95%.

Results

A total of 174 booked HIV women participated in this study. The placental malaria parasitaemia prevalence was 44.8%. Overall rate of MTCT of HIV infection was 17.2%. Number of infants with HIV infection among women with maternal placental malarial parasitaemia was 30/78 (38.5%), while it was 0/96 (0%) for women without placenta malaria. There was significant relationship between placenta malaria density and infant HIV status (P-value = 0.001). The relative risk for MTCT of HIV for women with placenta malaria Density > 5000 was 25% with 95% confidence interval of 11.41–54.76%.

Conclusion

The mother-to-child transmission rate of HIV was high among HIV positive women with placental malaria parasitaemia. There is the need to review the malarial treatment and prophylactic measures at least in this group of women and to establish the nature of relationship between placenta malaria and MTCT of HIV infection.

Malaria in pregnancy shapes the development of foetal and infant immunity

Malaria, particularly Plasmodium falciparum, continues to disproportionately affect pregnant women. In addition to the profoundly deleterious impact of maternal malaria on the health of the mother and foetus, malaria infection in pregnancy has been shown to affect the development of the foetal and infant immune system and may alter the risk of malaria and nonmalarial outcomes during infancy. This review summarizes our current understanding of how malaria infection in pregnancy shapes the protective components of the maternal immune system transferred to the foetus and how foetal exposure to parasite antigens impacts the development of foetal and infant immunity. It also reviews existing evidence linking malaria infection in pregnancy to malaria and nonmalarial outcomes in infancy and how preventing malaria in pregnancy may alter these outcomes. A better understanding of the consequences of malaria infection in pregnancy on the development of foetal and infant immunity will inform control strategies, including intermittent preventive treatment in pregnancy and vaccine development.

Rottlerin-mediated inhibition of Toxoplasma gondii growth in BeWo trophoblast-like cells

Autophagy is a crucial and physiological process for cell survival from yeast to mammals, including protozoan parasites. Toxoplasma gondii, an intracellular parasite, typically exploits autophagic machinery of host cell; however host cell upregulates autophagy to combat the infection. Herein we tested the efficacy of Rottlerin, a natural polyphenol with autophagic promoting properties, against Toxoplasma infection on the chorioncarcinoma-derived cell line BeWo. We found that Rottlerin, at sub-toxic doses, induced morphological and biochemical alterations associated with autophagy and decreased Toxoplasma growth in infected cells. Although autophagy was synergically promoted by Toxoplasma infection in combination with Rottlerin treatment, the use of the autophagy inhibitor chloroquine revealed that Rottlerin anti-parasitic effect was largely autophagy-independent and likely mediated by the converging inhibitory effect of Rottlerin and Toxoplasma in host protein translation, mediated by mTOR inhibition and eIF2α phosphorylation. Both events, which on one hand could explain the additive effect on autophagy induction, on the other hand led to inhibition of protein synthesis, thereby depriving Toxoplasma of metabolically essential components for multiplication. We suggest that modulation of the competition between pathogen requirement and host cell defense might be an attractive, novel therapeutic approach against Toxoplasma infection and encourage the development of Rottlerin-based new therapeutic formulations.

Knudsen L, Damm P, G. Theander T, R. Hansson S, A. Nielsen M, Salanti A. Placental Sequestration of Plasmodium falciparum Malaria Parasites Is Mediated by the Interaction Between VAR2CSA and Chondroitin Sulfate A on Syndecan-1

During placental malaria, Plasmodium falciparum infected erythrocytes sequester in the placenta, causing health problems for both the mother and fetus. The specific adherence is mediated by the VAR2CSA protein, which binds to placental chondroitin sulfate (CS) on chondroitin sulfate proteoglycans (CSPGs) in the placental syncytium. However, the identity of the CSPG core protein and the cellular impact of the interaction have remain elusive. In this study we identified the specific CSPG core protein to which the CS is attached, and characterized its exact placental location. VAR2CSA pull-down experiments using placental extracts from whole placenta or syncytiotrophoblast microvillous cell membranes showed three distinct CSPGs available for VAR2CSA adherence. Further examination of these three CSPGs by immunofluorescence and proximity ligation assays showed that syndecan-1 is the main receptor for VAR2CSA mediated placental adherence. We further show that the commonly used placental choriocarcinoma cell line, BeWo, express a different set of proteoglycans than those present on placental syncytiotrophoblast and may not be the most biologically relevant model to study placental malaria. Syncytial fusion of the BeWo cells, triggered by forskolin treatment, caused an increased expression of placental CS-modified syndecan-1. In line with this, we show that rVAR2 binding to placental CS impairs syndecan-1-related Src signaling in forskolin treated BeWo cells, but not in untreated cells.

Plasmodium falciparum is the most deadly malaria parasite, causing more than 500,000 deaths each year. The parasite infects the host’s red blood cells. In placental malaria infected red blood cells accumulate in placenta. The parasite protein VAR2CSA mediates this adherence, which causes complications for both mother and child. VAR2CSA binds a carbohydrate chain termed chondroitin sulfate (CS). CS is not a well-defined biochemical entity but constitute a family of oligosaccharides which each have unique sulfation patterns. The CS binding VAR2CSA is attached to proteoglycans expressed on the surface of placental cells. While much work has gone into understanding the nature of VAR2CSA and its interaction with placental CS, the protein to which the placental CS is attached is not known. To further the understanding of the molecular pathology of PM we characterized the CSPG receptor that the parasites adhere to by defining the exact proteoglycan that carries the placental CS. We further investigated the molecular and cellular consequences of VAR2CSA binding to the receptor. This work provides novel insights into the pathology of placental malaria and the nature of the parasite receptor. This may aid development of strategies to treat or prevent placental malaria.

Effect of malaria on HIV/AIDS transmission and progression

Malaria and HIV are among the two most important global health problems of developing countries. They cause more than 4 million deaths a year. These two infections interact bidirectionally and synergistically with each other. HIV infection increases the risk of an increase in the severity of malaria infection and burdens of malaria, which in turn facilitates the rate of malaria transmission. Malaria infection is also associated with strong CD4+ cell activation and up-regulation of proinflammatory cytokines and it provides an ideal microenvironment for the spread of the virus among the CD4+ cells and for rapid HIV-1 replication. Additionally, malaria increases blood viral burden by different mechanisms. Therefore, high concentrations of HIV-1 RNA in the blood are predictive of disease progression, and correlate with the risk of blood-borne, vertical, and sexual transmission of the virus. Therefore, this article aims to review information about HIV malaria interactions, the effect of malaria on HIV transmission and progression and the implications related to prevention and treatment of coinfection.

The role of co-infections in mother-to-child transmission of HIV

In HIV-infected women, co-infections that target the placenta, fetal membranes, genital tract, and breast tissue, as well as systemic maternal and infant infections, have been shown to increase the risk for mother-to-child transmission of HIV (MTCT). Active co-infection stimulates the release of cytokines and inflammatory agents that enhance HIV replication locally or systemically and increase tissue permeability, which weakens natural defenses to MTCT. Many maternal or infant co-infections can affect MTCT of HIV, and particular ones, such as genital tract infection with herpes simplex virus, or systemic infections such as hepatitis B, can have substantial epidemiologic impact on MTCT. Screening and treatment for co-infections that can make infants susceptible to MTCT in utero, peripartum, or postpartum can help reduce the incidence of HIV infection among infants and improve the health of mothers and infants worldwide.

Mechanisms of interaction between protozoan parasites and HIV

PURPOSE OF REVIEW

This review summarizes the current knowledge on human immunodeficiency virus type 1 (hereinafter called HIV)/protozoan co-infections in the case of three important, although neglected, tropical diseases: malaria, trypanosomiasis (Chagas disease) and leishmaniasis. The HIV pandemic has modified the immunopathogenic, epidemiological and therapeutic aspects of these human diseases.

RECENT FINDINGS

In-vitro data suggests that HIV favors Leishmania infection, whereas different parasites have contrasting effects on HIV. However, many of the previous models are a limited representation of the complex interactions within the host; this situation is particularly the case when microbial products are used in place of live parasites.

SUMMARY

In the host, protozoan parasites generally enhance HIV replication and accelerate AIDS progression. HIV alters parasite pathogenesis, often worsening disease outcome. These aspects bring significant complications for the treatment of co-infected individuals.

Host factors that influence mother-to-child transmission of HIV-1: genetics, coinfections, behavior and nutrition

Mother-to-child transmission (MTCT) is the most important mode of HIV-1 acquisition among infants and children and it can occur in utero, intrapartum and postnatally through breastfeeding. Great progress has been made in preventing MTCT through use of antiretroviral regimens during gestation, labor/delivery and breastfeeding. The mechanisms of MTCT, however, are multifactorial and remain incompletely understood. This review focuses on select host factors affecting MTCT, in particular genetic factors, coexisting infections, behavioral factors and nutrition. Whereas much emphasis has been placed on decreasing maternal HIV-1 viral load, an important determinant of MTCT, through use of antiretroviral agents, complementary focus on overall maternal health is often neglected. By addressing coinfections in mothers and infants, improving the mother's nutritional status and modifying risky behaviors and practices, not only is maternal and child health improved, but a direct benefit in reducing MTCT can be derived. The study of genetic variations in susceptibility to HIV-1 infection is rapidly evolving, and the future is likely to bring revolutionary changes in HIV-1 prevention by enhancing natural resistance to infection and by individually tailoring pharmacologic regimens.

[Influence of HIV-1 and placental malaria co-infection on newborn biometry and Apgar scores in Kinshasa, Democratic Republic of Congo]

OBJECTIVE

The aim of this study was to assess the impact of HIV-1 and placental malaria co-infection on newborn biometry and Apgar scores.

METHODS

146 HIV-1 infected and 149 HIV-1 uninfected consent mothers and their newborns were recruited. Placental biopsies examination confirmed the presence or absence of placental malaria. Birth weight (BW), placental weight, cranial circumference, brachial perimeter, height, Body Mass Index (BMI) and Apgar scores at 1', 5', 10' were taken. The Chi(2) test and t-Student test were used for data statistical analysis.

RESULTS

The global placental malarial infection prevalence was 72% but was 91% in HIV-1 infected vs. 53.7% in HIV-1 uninfected mothers (p<0.0001). The mean BW of HIV-1 co-infected mother's newborns was slightly inferior to that of HIV-1 uninfected mother's babies (3,033±524g vs. 3,236±565g) but this difference was not statistically significant (p>0.05). No other significant biometric differences were noted (p>0.05). But, the co-infection influenced negatively Apgar scores at 5' (p<0.05).

CONCLUSION

HIV-1 co-infected mothers were more frequently exposed to placental malaria infection. The co-infection reduced the Apgar scores taken at the fifth minute.

Mother-to-child transmission of HIV: pathogenesis, mechanisms and pathways

More than 400,000 children were infected with (HIV-1) worldwide in 2008, or more than 1000 children per day. Mother-to-child transmission (MTCT) of HIV-1 is the most important mode of HIV acquisition in infants and children. MTCT of HIV-1 can occur in utero, intrapartum, and postnatally through breastfeeding. Great progress has been made in preventing such transmission, through the use of antiretroviral prophylactic regimens to the mother during gestation and labor and delivery and to either mother or infant during breast feeding. The timing and mechanisms of transmission, however, are multifactorial and remain incompletely understood. This article summarizes what is known about the pathogenetic mechanisms and routes of MTCT of HIV-1, and includes virologic, immunologic, genetic, and mucosal aspects of transmission.

[Impact of malaria on HIV infection]

Malaria and HIV are two major public health issues, especially in sub-Saharan Africa. HIV infection increases the incidence of clinical malaria, inversely correlated with the degree of immunodepression. The effect of malaria on HIV infection is not as well established. Malaria, when fever and parasitemia are high, may be associated with transient increases in HIV viral load. The effect of subclinical malaria on HIV viral load is uncertain. During pregnancy, placental malaria is associated with higher plasma and placental HIV viral loads, independently of the severity of immunodeficiency. However, the clinical impact of these transient increases of HIV viral load remains unknown. Although some data suggests that malaria might enhance sexual and mother-to-child transmissions, no clinical study has confirmed this. Nevertheless pregnant women and children with malaria-induced anemia are also exposed to HIV through blood transfusions. Integrated HIV and malaria control programs in the regions where both infections overlap are necessary.

The Impact of HIV and Malaria Coinfection: What Is Known and Suggested Venues for Further Study

HIV and malaria have similar global distributions. Annually, 500 million are infected and 1 million die because of malaria. 33 million have HIV and 2 million die from it each year. Minor effects of one infection on the disease course or outcome for the other would significantly impact public health because of the sheer number of people at risk for coinfection. While early population-based studies showed no difference in outcomes between HIV-positive and HIV-negative individuals with malaria, more recent work suggests that those with HIV have more frequent episodes of symptomatic malaria and that malaria increases HIV plasma viral load and decreases CD4+ T cells. HIV and malaria each interact with the host's immune system, resulting in a complex activation of immune cells, and subsequent dysregulated production of cytokines and antibodies. Further investigation of these interactions is needed to better define effects of coinfection.

Placental malaria, maternal HIV infection and infant morbidity

Co-infection with malaria and HIV in pregnant women is particularly common in sub-Saharan Africa and has serious consequences for both mother and newborn child. Numerous studies have been published on the effects in pregnancy of HIV on malaria infection and on the effects of malaria on HIV infection. The increased prevalence and intensity of parasitaemia (placental and peripheral infection and parasite density) in HIV-infected women is well established. Similarly, malaria infection seems to be associated with higher viral loads. However, there is still uncertainty as to the influence of malaria on the clinical course of HIV infection, mother-to-child transmission of HIV, and the consequences of co-infection on post-neonatal infant morbidity and mortality. These questions require further investigation. In terms of prevention, intermittent preventive treatment with two doses of sulfadoxine-pyrimethamine (SP) has been found less effective in preventing malaria in HIV-infected than uninfected women, and a higher dosage (such as monthly SP) has been recommended. Regarding malaria, there is also a lack of clear recommendations for women taking daily cotrimoxazole prophylaxis, and anti-malarial-anti-retroviral interactions are not well understood. Multi-centre clinical trials should be undertaken to investigate effective, coherent and well-tolerated strategies to prevent malaria in HIV-infected women. Safe alternatives to SP should be identified and evaluated rapidly. Finally, a central pharmaco-vigilance network should be instituted to report adverse effects.

Role of placenta in the vertical transmission of human immunodeficiency virus

OBJECTIVE

Review the role and mechanism of in utero placental transmission of HIV-1.

STUDY DESIGN

A thorough review based on a literature search for publications relevant to this subject was performed using relevant search terms. Articles that describe the genetic and pathophysiology of vertical transmission have been acknowledged. The articles pertinent to the topic were selected to support the discussion.

RESULTS

Vertical transmission may occur through CD4+ endothelial tissues or CD4+ Hofbauer cells. Trophoblasts and villi have CD4 receptors, which make them potential candidates for HIV infection. Placental cytokines and chemokines influence HIV replication in trophoblasts. Genetic analysis of HIV-1 sequences verify the interaction of HIV-1 and placental tissue. The vertical transmission of HIV-1 characterized by selection of genotype variant that escape the mother's immune system.

CONCLUSION

Placental transmission of HIV-1 is a complex incompletely understood process which requires advanced studies. The available literature provides information with regards to the interactions of placental cells with HIV.