The Liver Plays a Major Role in Clearance and Destruction of Blood Trypomastigotes in Trypanosoma cruzi Chronically Infected Mice

Intravenous challenge with Trypanosoma cruzi can be used to investigate the process and consequences of blood parasite clearance in experimental Chagas disease. One hour after intravenous challenge of chronically infected mice with 5×106 trypomastigotes, the liver constituted a major site of parasite accumulation, as revealed by PCR. Intact parasites and/or parasite remnants were visualized at this time point scattered in the liver parenchyma. Moreover, at this time, many of liver-cleared parasites were viable, as estimated by the frequency of positive cultures, which considerably diminished after 48 h. Following clearance, the number of infiltrating cells in the hepatic tissue notably increased: initially (at 24 h) as diffuse infiltrates affecting the whole parenchyma, and at 48 h, in the form of large focal infiltrates in both the parenchyma and perivascular spaces. Phenotypic characterization of liver-infiltrating cells 24 h after challenge revealed an increase in Mac1+, CD8+ and CD4+ cells, followed by natural killer (NK) cells. As evidence that liver-infiltrating CD4+ and CD8+ cells were activated, increased frequencies of CD69+CD8+, CD69+CD4+ and CD25+CD122+CD4+ cells were observed at 24 and 48 h after challenge, and of CD25−CD122+CD4+ cells at 48 h. The major role of CD4+ cells in liver protection was suggested by data showing a very high frequency of interferon (IFN)-γ-producing CD4+ cells 24 h after challenge. In contrast, liver CD8+ cells produced little IFN-γ, even though they showed an enhanced potential for secreting this cytokine, as revealed by in vitro T cell receptor (TCR) stimulation. Confirming the effectiveness of the liver immune response in blood parasite control during the chronic phase of infection, no live parasites were detected in this organ 7 days after challenge

Adverse pregnancy outcomes are associated with Plasmodium vivax malaria in a prospective cohort of women from the Brazilian Amazon.

BACKGROUND: Malaria in Brazil represents one of the highest percentages of Latin America cases, where approximately 84% of infections are attributed to Plasmodium (P.) vivax. Despite the high incidence, many aspects of gestational malaria resulting from P. vivax infections remain poorly studied. As such, we aimed to evaluate the consequences of P. vivax infections during gestation on the health of mothers and their neonates in an endemic area of the Amazon. METHODS AND FINDINGS: We have conducted an observational cohort study in Brazilian Amazon between January 2013 and April 2015. 600 pregnant women were enrolled and followed until delivery. After applying exclusion criteria, 329 mother-child pairs were included in the analysis. Clinical data regarding maternal infection, newborn's anthropometric measures, placental histopathological characteristics, and angiogenic and inflammatory factors were evaluated. The presence of plasma IgG against the P. vivax (Pv) MSP119 protein was used as marker of exposure and possible associations with pregnancy outcomes were analyzed. Multivariate logistic regression analysis revealed that P. vivax infections during the first trimester of pregnancy are associated with adverse gestational outcomes such as premature birth (adjusted odds ratio [aOR] 8.12, 95% confidence interval [95%CI] 2.69-24.54, p < 0.0001) and reduced head circumference (aOR 3.58, 95%CI 1.29-9.97, p = 0.01). Histopathology analysis showed marked differences between placentas from P. vivax-infected and non-infected pregnant women, especially regarding placental monocytes infiltrate. Placental levels of vasomodulatory factors such as angiopoietin-2 (ANG-2) and complement proteins such as C5a were also altered at delivery. Plasma levels of anti-PvMSP119 IgG in infected pregnant women were shown to be a reliable exposure marker; yet, with no association with improved pregnancy outcomes. CONCLUSIONS: This study indicates that P. vivax malaria during the first trimester of pregnancy represents a higher likelihood of subsequent poor pregnancy outcomes associated with marked placental histologic modification and angiogenic/inflammatory imbalance. Additionally, our findings support the idea that antibodies against PvMSP119 are not protective against poor pregnancy outcomes induced by P. vivax infections

Association of Malaria Infection During Pregnancy With Head Circumference of Newborns in the Brazilian Amazon.

Importance: Malaria during pregnancy is associated with adverse events for the fetus and newborn, but the association of malaria during pregnancy with the head circumference of the newborn is unclear. Objective: To investigate the association of malaria during pregnancy with fetal head growth. Design, Setting, and Participants: Two cohort studies were conducted at the general maternity hospital of Cruzeiro do Sul (Acre, Brazil) in the Amazonian region. One cohort study prospectively enrolled noninfected and malaria-infected pregnant women who were followed up until delivery, between January 2013 and April 2015. The other cohort study was assembled retrospectively using clinical and malaria data from all deliveries that occurred between January 2012 and December 2013. Data analyses were conducted from January to August 2017 and revised in November 2018. Clinical data from pregnant women and anthropometric measures of their newborns were evaluated. A total of 600 pregnant women were enrolled through volunteer sampling (prospective cohort study), and 4697 pregnant women were selected by population-based sampling (retrospective cohort study). After application of exclusion criteria, data from 251 (prospective cohort study) and 232 (retrospective cohort study) malaria-infected and 158 (prospective cohort study) and 3650 (retrospective cohort study) noninfected women were evaluated. Exposure: Malaria during pregnancy. Main Outcomes and Measures: The primary end point was the incidence of altered head circumference in newborns delivered from malaria-infected mothers compared with that from noninfected mothers. Secondary end points included measures of placental pathology relative to newborn head circumference. Results: In total, 4291 maternal-child pairs were analyzed. Among 409 newborns in the prospective cohort study, the mothers of 251 newborns had malaria during pregnancy, infected with Plasmodium vivax, Plasmodium falciparum, or both. Among 3882 newborns in the retrospective cohort study, 232 were born from mothers that had malaria during pregnancy. The prevalence of newborns with a small head (19 [30.7%] in the prospective cohort study and 30 [36.6%] in the retrospective cohort study) and the prevalence of microcephaly among newborns (5 [8.1%] in the prospective cohort study and 6 [7.3%] in the retrospective cohort study) were higher among newborns from women infected with P falciparum during pregnancy. Multivariate logistic regression analyses revealed that P falciparum infection during pregnancy represented a significant risk factor for the occurrence of small head circumference in newborns (prospective cohort study: odds ratio, 3.15; 95% CI, 1.52-6.53; P = .002; retrospective cohort study: odds ratio, 1.91; 95% CI, 1.21-3.04; P = .006). Placental pathologic findings corroborated this association, with more syncytial nuclear aggregates and inflammatory infiltrates occurring in placentas of newborns born with decreased head circumference. Conclusions and Relevance: This study indicates that falciparum malaria during pregnancy is associated with decreased head circumference in newborns, which is in turn associated with evidence of placental malaria

In Vivo Approaches Reveal a Key Role for DCs in CD4+ T Cell Activation and Parasite Clearance during the Acute Phase of Experimental Blood-Stage Malaria

Dendritic cells (DCs) are phagocytes that are highly specialized for antigen presentation. Heterogeneous populations of macrophages and DCs form a phagocyte network inside the red pulp (RP) of the spleen, which is a major site for the control of blood-borne infections such as malaria. However, the dynamics of splenic DCs during Plasmodium infections are poorly understood, limiting our knowledge regarding their protective role in malaria. Here, we used in vivo experimental approaches that enabled us to deplete or visualize DCs in order to clarify these issues. To elucidate the roles of DCs and marginal zone macrophages in the protection against blood-stage malaria, we infected DTx (diphtheria toxin)-treated C57BL/6.CD11c-DTR mice, as well as C57BL/6 mice treated with low doses of clodronate liposomes (ClLip), with Plasmodium chabaudi AS (Pc) parasites. The first evidence suggesting that DCs could contribute directly to parasite clearance was an early effect of the DTx treatment, but not of the ClLip treatment, in parasitemia control. DCs were also required for CD4+ T cell responses during infection. The phagocytosis of infected red blood cells (iRBCs) by splenic DCs was analyzed by confocal intravital microscopy, as well as by flow cytometry and immunofluorescence, at three distinct phases of Pc malaria: at the first encounter, at pre-crisis concomitant with parasitemia growth and at crisis when the parasitemia decline coincides with spleen closure. In vivo and ex vivo imaging of the spleen revealed that DCs actively phagocytize iRBCs and interact with CD4+ T cells both in T cell-rich areas and in the RP. Subcapsular RP DCs were highly efficient in the recognition and capture of iRBCs during pre-crisis, while complete DC maturation was only achieved during crisis. These findings indicate that, beyond their classical role in antigen presentation, DCs also contribute to the direct elimination of iRBCs during acute Plasmodium infection.São Paulo Research Foundation grants: (2011/24038-1 [MRDL], 2009/08559-1 [HBdS], CAPES/IGC 04/ 2012 [MRDL, CET])

Avaliação de parâmetros comportamentais, hematológicos e sanitários na utilização de flocos de pinus elliottii como forração de gaiolas para camundongos isogênicos

Introdução: a forração de gaiolas para animais de laboratório, assim como o tempo de higienização delas, é um dos fatores mais importantes para seu microambiente. Este trabalho teve como objetivo avaliar dois tipos de forração de gaiolas, com tempo de higienização quinzenal. Metodologia: avaliamos dois tipos de forração de gaiolas, provenientes da madeira com gramaturas diferenciadas, maravalha e flocos de Pinus elliottii. Os animais foram pesados e medidas das patas traseiras foram aferidas semanalmente. Dados de comportamento, como movimentação nas gaiolas, nidificação, mortalidade, fertilidade entre outros, também foram realizados durante todo o estudo por meio de gravações noturnas e diurnas, assim como amostras de sangue foram coletadas para análise hematológica. Resultados: a forração de gaiolas com flocos de Pinus foi considerada uma eficaz substituição à de maravalha na higienização quinzenal; na avaliação fisiológica, não houve diferença significativa entre as duas forrações quanto a peso, temperatura e medida das patas traseiras; já na análise hematológica entre os grupos, os animais mantidos em gaiolas com forração de maravalha com higienização quinzenal apresentaram um aumento nos valores de hematócrito. Esses resultados foram corroborados pelo exame histopatológico dos pulmões de animais Balb/c, que revelaram congestão pulmonar, edema peribronquiolar e peripleural sugerindo síndrome respiratória. Conclusões: o flocos de Pinus foi considerado uma boa opção como forração de gaiolas, visto que o material foi considerado eficaz por não trazer danos respiratórios aos animais mantidos em confinamento pelo período de duas semanas sem higienização e por manter o mesmo perfil de comportamento que a maravalha de Pinus

Avaliação de parâmetros comportamentais, hematológicos e sanitários na utilização de flocos de pinus elliottii como forração de gaiolas para camundongos isogênicos

Introdução: a forração de gaiolas para animais de laboratório, assim como o tempo de higienização delas, é um dos fatores mais importantes para seu microambiente. Este trabalho teve como objetivo avaliar dois tipos de forração de gaiolas, com tempo de higienização quinzenal. Metodologia: avaliamos dois tipos de forração de gaiolas, provenientes da madeira com gramaturas diferenciadas, maravalha e flocos de Pinus elliottii. Os animais foram pesados e medidas das patas traseiras foram aferidas semanalmente. Dados de comportamento, como movimentação nas gaiolas, nidificação, mortalidade, fertilidade entre outros, também foram realizados durante todo o estudo por meio de gravações noturnas e diurnas, assim como amostras de sangue foram coletadas para análise hematológica. Resultados: a forração de gaiolas com flocos de Pinus foi considerada uma eficaz substituição à de maravalha na higienização quinzenal; na avaliação fisiológica, não houve diferença significativa entre as duas forrações quanto a peso, temperatura e medida das patas traseiras; já na análise hematológica entre os grupos, os animais mantidos em gaiolas com forração de maravalha com higienização quinzenal apresentaram um aumento nos valores de hematócrito. Esses resultados foram corroborados pelo exame histopatológico dos pulmões de animais Balb/c, que revelaram congestão pulmonar, edema peribronquiolar e peripleural sugerindo síndrome respiratória. Conclusões: o flocos de Pinus foi considerado uma boa opção como forração de gaiolas, visto que o material foi considerado eficaz por não trazer danos respiratórios aos animais mantidos em confinamento pelo período de duas semanas sem higienização e por manter o mesmo perfil de comportamento que a maravalha de Pinus