Nitric oxide contributes to liver inflammation and parasitic burden control in Ascaris suum infection.

BACKGROUND: Human ascariasis is one of the most prevalent neglected tropical diseases worldwide. The immune response during human ascariasis is characterized by Th2 polarization and a mixed Th2/Th17 response during the pathogenesis of experimental larval ascariasis. Cytokines and other pro-inflammatory mediators, such as nitric oxide (NO), are involved in helminthic infections. However, the role of NO in ascariasis remains unclear. OBJECTIVES: Given the importance of NO in inflammation, we aimed to determine the immunological and histopathological alterations in the livers of C57BL/6 iNOS-/- mice during A. suum infection. METHODS: In this study, parasitic load was evaluated in the livers of wild type C57BL/6 and C57BL/6 iNOS-/- mice infected with A. suum. Histopathological and morphometric analyses and analysis of serum cytokines via Cytometric Bead Array were performed, and the activity of eosinophil peroxidase and myeloperoxidase of neutrophils in the tissues were determined. RESULTS: The results showed that NO is important for controlling parasitic load during infection by A. suum. C57BL/6iNOS-/- mice showed reduced inflammatory processes and less tissue damage during liver larval migration of A. suum, which is associated with a reduction in serum levels of pro-inflammatory cytokines. CONCLUSIONS: We demonstrated that NO is a crucial inflammatory molecule during Ascaris sp. infection and controls the establishment of the parasite and the development of the host immune response in the liver.

Deletion of MIF gene from live attenuated LdCen-/- parasites enhances protective CD4+ T cell immunity.

Vaccination with live attenuated Leishmania parasites such as centrin deleted Leishmania donovani (LdCen-/-) against visceral leishmaniasis has been reported extensively. The protection induced by LdCen-/- parasites was mediated by both CD4+ and CD8+ T cells. While the host immune mediators of protection are known, parasite determinants that affect the CD4+ and CD8+ T cell populations remain unknown. Parasite encoded inflammatory cytokine MIF has been shown to modulate the T cell differentiation characteristics by altering the inflammation induced apoptosis during contraction phase in experimental infections with Leishmania or Plasmodium. Neutralization of parasite encoded MIF either by antibodies or gene deletion conferred protection in Plasmodium and Leishmania studies. We investigated if the immunogenicity and protection induced by LdCen-/- parasites is affected by deleting MIF genes from this vaccine strain. Our results showed that LdCen-/-MIF-/- immunized group presented higher percentage of CD4+ and CD8+ central memory T cells, increased CD8+ T cell proliferation after challenge compared to LdCen-/- immunization. LdCen-/-MIF-/- immunized group presented elevated production of IFN-γ+ and TNF-α+ CD4+ T cells concomitant with a reduced parasite load in spleen and liver compared to LdCen-/-group following challenge with L. infantum. Our results demonstrate the role of parasite induced factors involved in protection and long-term immunity of vaccines against VL.

Retrospective cohort study to evaluate the continuous use of anticholesterolemics and diuretics in patients with COVID-19.

Purpose: The purpose of this study is to evaluate the interference of the continuous use of drug classes in the expression of biomarkers during the first week of hospitalization and in the prognosis of patients with COVID-19. Methods: The patients diagnosed with COVID-19 and confirmed with SARS-CoV-2 by RT-qPCR assay underwent the collection of fasting whole blood samples for further analysis. Other data also extracted for this study included age, sex, clinical symptoms, related comorbidities, smoking status, and classes of continuous use. Routine serum biochemical parameters, including alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, C-reactive protein, N-terminal fragment of B-type natriuretic peptide, and cardiac troponin, were measured. Results: In this cross-sectional study, a total of 176 patients with COVID-19 hospitalizations were included. Among them, 155 patients were discharged (88.5%), and 21 patients died (12%). Among the drug classes evaluated, we verified that the continuous use of diuretic 4.800 (1.853-11.67) (p = 0.0007) and antihypercholesterolemic 3.188 (1.215-7.997) (p = 0.0171) drug classes presented a significant relative risk of death as an outcome when compared to the group of patients who were discharged. We evaluated biomarkers in patients who used continuous antihypercholesterolemic and diuretic drug classes in the first week of hospitalization. We observed significant positive correlations between the levels of CRP with cardiac troponin (r = 0.714), IL-6 (r = 0.600), and IL-10 (r = 0.900) in patients who used continuous anticholesterolemic and diuretic drug classes and were deceased. In these patients, we also evaluated the possible correlations between the biomarkers AST, NT-ProBNP, cardiac troponin, IL-6, IL-8, and IL-10. We observed a significantly negative correlations in AST levels with NT-ProBNP (r = -0.500), cardiac troponin (r = -1.00), IL-6 (r = -1.00), and IL-10 (r = -1.00) and a positive correlation with IL-8 (r = 0.500). We also observed significant negative correlation in the levels of NT-ProBNP with IL-10 (r = -0.800) and a positive correlation with cardiac troponin (r = 0.800). IL-6 levels exhibited positive correlations with cardiac troponin (r = 0.800) and IL-10 (r = 0.700). Conclusion: In this study, we observed that hospitalized COVID-19 patients who continued using anticholesterolemic and diuretic medications showed a higher number of correlations between biomarkers, indicating a poorer clinical prognosis. These correlations suggest an imbalanced immune response to injuries caused by SARS-CoV-2.

HIV aspartyl protease inhibitors modify the percentage of activated leukocytes, as well as serum levels of IL-17A and NO during experimental leishmaniasis.

HIV aspartyl protease inhibitors are able to modulate multiple defense mechanisms. However, their influence on the immune response against Leishmania has rarely been investigated. The aim of our study was to investigate whether in vivo treatment with HIV aspartyl protease inhibitors is able to modulate the immune response during Leishmania infection. Using Leishmania (L.) amazonensis-infected mice, we analyzed the disease evolution and parasite load, immunophenotypic profiles of splenic T and B lymphocytes, numbers of lymphoid aggregates in the spleen, percentages of circulating atypical lymphocytes and reactive monocytes, and serum levels of cytokines and nitric oxide (NO) after 30 days of oral treatment with lopinavir/ritonavir (LPV/RTV) or atazanavir (ATV). We observed that LPV/RTV and ATV did not modify the disease evolution or parasite load. However, the antiretroviral treatment induced an increase in activated lymphocytes in the spleen and blood, as well as a decrease in CD69 expression in T and B lymphocytes in the spleen. The treatment also resulted in an increase in activated monocytes in the blood. In addition, antiretrovirals decreased levels of IL-17A and increased levels of NO in sera from Leishmania-infected mice. Thus, our results demonstrate for the first time that in vivo treatment with HIV aspartyl protease inhibitors modifies innate and adaptative immune responses during Leishmania infection and suggest that these drugs could change the clinical course of leishmaniasis in HIV infected-individuals.

Genome of the human hookworm Necator americanus.

The hookworm Necator americanus is the predominant soil-transmitted human parasite. Adult worms feed on blood in the small intestine, causing iron-deficiency anemia, malnutrition, growth and development stunting in children, and severe morbidity and mortality during pregnancy in women. We report sequencing and assembly of the N. americanus genome (244 Mb, 19,151 genes). Characterization of this first hookworm genome sequence identified genes orchestrating the hookworm's invasion of the human host, genes involved in blood feeding and development, and genes encoding proteins that represent new potential drug targets against hookworms. N. americanus has undergone a considerable and unique expansion of immunomodulator proteins, some of which we highlight as potential treatments against inflammatory diseases. We also used a protein microarray to demonstrate a postgenomic application of the hookworm genome sequence. This genome provides an invaluable resource to boost ongoing efforts toward fundamental and applied postgenomic research, including the development of new methods to control hookworm and human immunological diseases.