Julie M. Moore

Immunity to placental malaria. IV. Placental malaria is associated with up-regulation of macrophage migration inhibitory factor in intervillous blood.

Macrophage migration inhibitory factor (MIF) may play a role in immune responses to malaria during pregnancy by virtue of its ability to activate macrophages and to overcome the immunosuppressive effect of glucocorticoids. The present study investigated whether plasma MIF levels are altered in pregnant women with placental malaria (PM) and/or human immunodeficiency virus (HIV) infection. For the first time it is demonstrated that MIF levels in the intervillous blood (IVB) plasma were significantly elevated, compared with that in both peripheral plasma ( approximately 500-fold) and cord plasma (4.6-fold; P<.01). IVB mononuclear cells also produced significantly higher levels of MIF, compared with that of peripheral blood mononuclear cells. PM was associated with increased levels of MIF in the IVB plasma (P<.02). Primigravid and secundigravid women had significantly higher levels of MIF in their IVB plasma than did multigravid women (P<.05). HIV infection did not significantly alter MIF levels in any site examined.

C5a Enhances Dysregulated Inflammatory and Angiogenic Responses to Malaria In Vitro: Potential Implications for Placental Malaria

Background Placental malaria (PM) is a leading cause of maternal and infant mortality. Although the accumulation of parasitized erythrocytes (PEs) and monocytes within the placenta is thought to contribute to the pathophysiology of PM, the molecular mechanisms underlying PM remain unclear. Based on the hypothesis that excessive complement activation may contribute to PM, in particular generation of the potent inflammatory peptide C5a, we investigated the role of C5a in the pathogenesis of PM in vitro and in vivo. Methodology and Principal Findings Using primary human monocytes, the interaction between C5a and malaria in vitro was assessed. CSA- and CD36-binding PEs induced activation of C5 in the presence of human serum. Plasmodium falciparum GPI (pfGPI) enhanced C5a receptor expression (CD88) on monocytes, and the co-incubation of monocytes with C5a and pfGPI resulted in the synergistic induction of cytokines (IL-6, TNF, IL-1β, and IL-10), chemokines (IL-8, MCP-1, MIP1α, MIP1β) and the anti-angiogenic factor sFlt-1 in a time and dose-dependent manner. This dysregulated response was abrogated by C5a receptor blockade. To assess the potential role of C5a in PM, C5a plasma levels were measured in malaria-exposed primigravid women in western Kenya. Compared to pregnant women without malaria, C5a levels were significantly elevated in women with PM. Conclusions and Significance These results suggest that C5a may contribute to the pathogenesis of PM by inducing dysregulated inflammatory and angiogenic responses that impair placental function.

Levels of Macrophage Inflammatory Protein 1α (MIP-1α) and MIP-1β in Intervillous Blood Plasma Samples from Women with Placental Malaria and Human Immunodeficiency Virus Infection

ABSTRACT Macrophage inflammatory protein-1α (MIP-1α) and MIP-1β play an important role in modulating immune responses. To understand their importance in immunity to placental malaria (PM) and in human immunodeficiency virus (HIV)-PM coinfection, we investigated levels of these chemokines in the placental intervillous blood plasma (IVB plasma) and cord blood plasma of HIV-negative PM-negative, HIV-negative PM-positive, HIV-positive PM-negative, and HIV-positive PM-positive women. Compared to HIV-negative PM-negative women, the MIP-1β concentration in IVB plasma was significantly elevated in HIV-negative PM-positive women and HIV-positive PM-positive women, but it was unaltered in HIV-positive PM-negative women. Also, PM-infected women, irrespective of their HIV status, had significantly higher levels of MIP-1β than HIV-positive PM-negative women. The MIP-1α level was not altered in association with either infection. The IVB plasma levels of MIP-1α and MIP-1β positively correlated with the cord blood plasma levels of these chemokines. As with IVB plasma, only cord plasma from PM-infected mothers had significantly elevated levels of MIP-1β compared to PM-negative mothers, irrespective of their HIV infection status. MIP-1β and MIP-1α levels in PM-positive women were positively associated with parasite density and malaria pigment levels. Regardless of HIV serostatus, the IVB MIP-1β level was significantly lower in women with PM-associated anemia. In summary, an elevated level of MIP-1β was associated with PM. HIV infection did not significantly alter these two chemokine levels in IVB plasma.

Immunity to Placental Malaria. III. Impairment of Interleukin(IL)–12, not IL-18, and Interferon-Inducible Protein–10 Responses in the Placental Intervillous Blood of Human Immunodeficiency Virus/Malaria–Coinfected Women

Pregnant women are highly susceptible to malaria, and human immunodeficiency virus (HIV) infection increases this susceptibility. In our previous studies, placental malaria (PM), HIV infection, and HIV/PM coinfection were all associated with decreased interferon (IFN)-gamma production by maternal placental (intervillous) blood mononuclear cells (IVBMC). This study investigated whether in vitro production of the IFN-gamma regulatory cytokines interleukin (IL)-12 and IL-18 and the chemokine IFN-inducible protein (IP)-10 by IVBMC is altered in women who have been exposed to malaria and are infected with HIV. IL-12 production from IVBMC was significantly lower in HIV-positive women, regardless of PM status, in contrast to HIV-negative, PM-negative women. IL-18 and IP-10 production by IVBMC was reduced in HIV-positive, PM-negative women but elevated in HIV-positive, PM-positive women. These results reveal a substantial impairment of IL-12 production by IVBMC in HIV-positive women, implicating this cytokine as a potentially critical regulator of malaria antigen-specific IFN-gamma responses in HIV-infected and HIV/PM-coinfected women.

Temporal trends of sulphadoxine-pyrimethamine (SP) drug-resistance molecular markers in Plasmodium falciparum parasites from pregnant women in western Kenya.

BackgroundResistance to sulphadoxine-pyrimethamine (SP) in Plasmodium falciparum parasites is associated with mutations in the dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) genes and has spread worldwide. SP remains the recommended drug for intermittent preventive treatment for malaria in pregnancy (IPTp) and information on population prevalence of the SP resistance molecular markers in pregnant women is limited.MethodsTemporal trends of SP resistance molecular markers were investigated in 489 parasite samples collected from pregnant women at delivery from three different observational studies between 1996 and 2009 in Kenya, where SP was adopted for both IPTp and case treatment policies in 1998. Using real-time polymerase chain reaction, pyrosequencing and direct sequencing, 10 single-nucleotide polymorphisms (SNPs) of SP resistance molecular markers were assayed.ResultsThe prevalence of quintuple mutant (dhfr N51I/C59R/S108N and dhps A437G/K540E combined genotype) increased from 7 % in the first study (1996–2000) to 88 % in the third study (2008–2009). When further stratified by sample collection year and adoption of IPTp policy, the prevalence of the quintuple mutant increased from 2.4 % in 1998 to 44.4 % three years after IPTp policy adoption, seemingly in parallel with the increase in percentage of SP use in pregnancy. However, in the 1996–2000 study, more mutations in the combined dhfr/dhps genotype were associated with SP use during pregnancy only in univariable analysis and no associations were detected in the 2002–2008 and 2008–2009 studies. In addition, in the 2008–2009 study, 5.3 % of the parasite samples carried the dhps triple mutant (A437G/K540E/A581G). There were no differences in the prevalence of SP mutant genotypes between the parasite samples from HIV + and HIV- women over time and between paired peripheral and placental samples.ConclusionsThere was a significant increase in dhfr/dhps quintuple mutant and the emergence of new genotype containing dhps 581 in the parasites from pregnant women in western Kenya over 13 years. IPTp adoption and SP use in pregnancy only played a minor role in the increased drug-resistant parasites in the pregnant women over time. Most likely, other major factors, such as the high prevalence of resistant parasites selected by the use of SP for case management in large non-pregnant population, might have contributed to the temporally increased prevalence of SP resistant parasites in pregnant women. Further investigations are needed to determine the linkage between SP drug resistance markers and efficacy of IPTp-SP.

Zika virus infection disrupts neurovascular development and results in postnatal microcephaly with brain damage

Zika virus (ZIKV) infection of pregnant women can result in fetal brain abnormalities. It has been established that ZIKV disrupts neural progenitor cells (NPCs) and leads to embryonic microcephaly. However, the fate of other cell types in the developing brain and their contributions to ZIKV-associated brain abnormalities remain largely unknown. Using intracerebral inoculation of embryonic mouse brains, we found that ZIKV infection leads to postnatal growth restriction including microcephaly. In addition to cell cycle arrest and apoptosis of NPCs, ZIKV infection causes massive neuronal death and axonal rarefaction, which phenocopy fetal brain abnormalities in humans. Importantly, ZIKV infection leads to abnormal vascular density and diameter in the developing brain, resulting in a leaky blood–brain barrier (BBB). Massive neuronal death and BBB leakage indicate brain damage, which is further supported by extensive microglial activation and astrogliosis in virally infected brains. Global gene analyses reveal dysregulation of genes associated with immune responses in virus-infected brains. Thus, our data suggest that ZIKV triggers a strong immune response and disrupts neurovascular development, resulting in postnatal microcephaly with extensive brain damage. Highlighted article: A postnatal model for ZIKV infection reveals blood-brain barrier leakage, neuronal death, apoptosis and cell cycle arrest of NPCs, leading to microcephaly with brain damage in ZIKV-infected pups.

Vertical Transmission of Babesia microti, United States

Babesiosis is usually acquired from a tick bite or through a blood transfusion. We report a case of babesiosis in an infant for whom vertical transmission was suggested by evidence of Babesia spp. antibodies in the heel-stick blood sample and confirmed by detection of Babesia spp. DNA in placenta tissue.

Immunohistological Characterization of Macrophage Migration Inhibitory Factor Expression in Plasmodium falciparum-Infected Placentas

ABSTRACT Previously, we have shown that macrophage migration inhibitory factor (MIF) was highly elevated in the placental intervillous blood (IVB) of Plasmodium falciparum-infected women. Here, we compared the expression of MIF in placental tissues obtained from P. falciparum-infected and -uninfected women. Immunoperoxidase staining showed a consistent pattern of MIF expression in syncytiotrophoblasts, extravillous trophoblasts, IVB mononuclear cells, and amniotic epithelial cells, irrespective of their malaria infection status. Cytotrophoblast, villous stroma, and Hofbauer cells showed focal staining. Only amniotic epithelial and IVB mononuclear cells from P. falciparum-infected placentas exhibited significantly higher level of MIF expression than uninfected placentas. Stimulation of syncytilized human trophoblast BeWo cells with P. falciparum-infected erythrocytes that were selected to bind these cells resulted in significant increases in MIF secretion, whereas control erythrocytes, lipopolysaccharides, and synthetic β-hematin had minimal effect. These findings suggest that placental malaria modulates MIF expression in different placental compartments.

Immunologic activation of human syncytiotrophoblast by Plasmodium falciparum

BackgroundMalaria during pregnancy is characterized by the sequestration of malaria-infected red blood cells (iRBC) in the intervillous spaces of the placenta, often accompanied by the infiltration of maternal mononuclear cells, causing substantial maternal and foetal/infant morbidity. The iRBC bind to receptors expressed by the syncytiotrophoblast (ST). How ST responds to this interaction remains poorly understood. Because it is known that ST is immunoactive and can respond to infectious agents, the consequences of this ST-iRBC interaction should be investigated.MethodsAn in vitro system was used to assess the biochemical and immunological changes induced in ST by ST-adherent iRBCs. Changes in ST mitogen-activated protein kinase (MAPK) activation were assessed by immunoblotting and mRNA expression levels of selected cytokine and chemokines in primary ST bound by iRBC were determined using real-time, reverse transcription PCR. In addition, secreted cytokine and chemokine proteins were assayed by standard ELISA, and chemotaxis of PBMC was assessed using a two-chamber assay system.ResultsFollowing iRBC/ST interaction, ST C-Jun N-terminal kinase 1 (JNK1) was activated and modest increases in the mRNA expression of TGF-β and IL-8/CXCL8 were observed. In addition, this interaction increased secretion of MIF and MIP-1α/CCL3 by ST and induced migration of PBMC towards iRBC-stimulated ST.ConclusionResults from this study provide the first evidence that ST participates in shaping the local immunological milieu and in the recruitment of maternal immune cells to the maternal blood space during placental malaria infection.

Murine malaria infection induces fetal loss associated with accumulation of Plasmodium chabaudi AS-infected erythrocytes in the placenta.

ABSTRACT Malarial infection in nonimmune women is a risk factor for pregnancy loss, but the role that maternal antimalarial immune responses play in fetal compromise is not clear. We conducted longitudinal and serial sacrifice studies to examine the pathogenesis of malaria during pregnancy using the Plasmodium chabaudi AS/C57BL/6 mouse model. Peak parasitemia following inoculation with 1,000 parasite-infected murine erythrocytes and survival were similar in infected pregnant and nonpregnant mice, although development of parasitemia and anemia was slightly accelerated in pregnant mice. Importantly, pregnant mice failed to maintain viable pregnancies, most aborting before day 12 of gestation. At abortion, maternal placental blood parasitemia was statistically significantly higher than peripheral parasitemia. Infected mice had similar increases in spleen size and cellularity which were statistically significantly higher than in uninfected mice. In contrast, splenocyte proliferation in response to mitogenic stimulation around peak parasitemia was statistically significantly reduced in both groups of infected mice compared to uninfected, nonpregnant mice, suggesting that lymphoproliferation is not a good indicator of the antimalarial immune responses in pregnant or nonpregnant animals. This study suggests that while pregnant and nonpregnant C57BL/6 mice are equally capable of mounting an effective immune response to and surviving P. chabaudi AS infection, pregnant mice cannot produce viable pups. Fetal loss appears to be associated with placental accumulation of infected erythrocytes. Further study is required to determine to what extent maternal antimalarial immune responses, anemia, and placental accumulation of parasites contribute to compromised pregnancy in this model.