Type I Interferon Transcriptional Signature in Neutrophils and Low-Density Granulocytes Are Associated with Tissue Damage in Malaria

Neutrophils are the most abundant leukocyte population in the bloodstream, the primary compartment of Plasmodium sp. infection. However, the role of these polymorphonuclear cells in mediating either the resistance or the pathogenesis of malaria is poorly understood. We report that circulating neutrophils from malaria patients are highly activated, as indicated by a strong type I interferon transcriptional signature, increased expression of surface activation markers, enhanced release of reactive oxygen species and myeloperoxidase, and a high frequency of low-density granulocytes. The activation of neutrophils was associated with increased levels of serum alanine and aspartate aminotransferases, indicating liver damage. In a rodent malaria model, we observed intense recruitment of neutrophils to liver sinusoids. Neutrophil migration and IL-1beta and chemokine expression as well as liver damage were all dependent on type I interferon signaling. The data suggest that type I interferon signaling has a central role in neutrophil activation and malaria pathogenesis

Reticulocyte count: comparison among methods

Introduction: The automated counting of reticulocytes has some advantages over the manual method routinely used in clinical laboratories. Technological innovations provide more statistically reliable results, while optimizing the time to perform this test. However, the cost for implementing the automated procedure in laboratory routines still constitutes a barrier to its use in small- and medium-size Brazilian laboratories. Objective: This study evaluated the performance of a new laboratory protocol for reticulocyte counting by flow cytometry using acridine orange (FC/AO), compared with the manual method and with another automated one by flow cytometry using the commercial kit BD Retic-Count (FC/RC) Conclusion: The results showed that, besides being comparable to the manual method, still considered standard, the evaluated new protocol is economically more advantageous than the automated methods currently available, and its cost is comparable to that of the manual method for laboratories that already have appropriate equipment and infrastructure

Neutrophil Paralysis in Plasmodium vivax Malaria

Plasmodium vivax is responsible for approximately 60–80% of the malaria cases in the world, and contributes to significant social and economic instability in the developing countries of Latin America and Asia. The pathogenesis of P. vivax malaria is a consequence of host derived inflammatory mediators. Hence, a better understanding of the mechanisms involved in induction of systemic inflammation during P. vivax malaria is critical for the clinical management and prevention of severe disease. The innate immune receptors recognize Plasmodium sp. and initiate a broad spectrum of host defense mechanisms that mediate resistance to infection. However, the innate immune response is the classic “two-edged sword”, and clinical malaria is associated with high levels of circulating pro-inflammatory cytokines. Our findings show that both monocytes and neutrophils are highly activated during malaria. Monocytes produced high levels of IL-1β, IL-6 and TNF-α during acute malaria. On the other hand, neutrophils were a poor source of cytokines, but displayed an enhanced phagocytic activity and superoxide production. Unexpectedly, we noticed an impaired chemotaxis of neutrophils towards an IL-8 (CXCL8) gradient. We proposed that neutrophil paralysis is in part responsible for the enhanced susceptibility to bacterial infection observed in malaria patients

Differential Use of TLR2 and TLR9 in the Regulation of Immune Responses during the Infection with Trypanosoma cruzi

Submitted by Nuzia Santos ([email protected]) on 2018-12-05T18:14:36Z No. of bitstreams: 1 Differential Use of TLR2 and TLR9 .pdf: 5776313 bytes, checksum: 3206b5a0f2e440a9c95d8318a58fc1f8 (MD5)Approved for entry into archive by Nuzia Santos ([email protected]) on 2018-12-05T18:20:21Z (GMT) No. of bitstreams: 1 Differential Use of TLR2 and TLR9 .pdf: 5776313 bytes, checksum: 3206b5a0f2e440a9c95d8318a58fc1f8 (MD5)Made available in DSpace on 2018-12-05T18:20:21Z (GMT). No. of bitstreams: 1 Differential Use of TLR2 and TLR9 .pdf: 5776313 bytes, checksum: 3206b5a0f2e440a9c95d8318a58fc1f8 (MD5) Previous issue date: 2013Universidade Federal de Minas Gerais. Departamento de Bioquímica e Imunologia. Belo Horizonte, MG, Brazil.Fundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Belo Horizonte, MG, BrazilFundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Belo Horizonte, MG, Brazil/Universidade Federal de Minas Gerais. Departamento de Bioquímica e Imunologia. Belo Horizonte, MG, Brazil/Division of Infectious Diseases and Immunology. University of Massachusetts Medical School. Worcester, MA, Untied States of America.Fundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Belo Horizonte, MG, BrazilPathogens express ligands for several TLRs that may play a role in the induction or control of the inflammatory response during infection. Concerning Trypanosoma cruzi, the agent of Chagas disease, we have previously characterized glycosylphosphatidylinositol (GPI) anchored mucin-like glycoproteins (tGPI-mucin) and unmethylated CpG DNA sequences as TLR2 and TLR9 agonists, respectively. Here we sought to determine how these TLRs may modulate the inflammatory response in the following cell populations: F4/80+CD11b+ (macrophages), F4/80lowCD11b+ (monocytes) and MHCII+CD11chigh (dendritic cells). For this purpose, TLR2−/− and TLR9−/− mice were infected with Y strain of T. cruzi and different immunological parameters were evaluated. According to our previous data, a crucial role of TLR9 was evidenced in the establishment of Th1 response, whereas TLR2 appeared to act as immunoregulator in the early stage of infection. More precisely, we demonstrated here that TLR2 was mainly used by F4/80+CD11b+ cells for the production of TNF-α. In the absence of TLR2, an increased production of IL-12/IL-23p40 and IFN-γ was noted suggesting that TLR2 negatively controls the Th1 response. In contrast, TLR9 was committed to IL-12/IL-23p40 production by MHCII+CD11chigh cells that constitute the main source of IL-12/IL-23p40 during infection. Importantly, a down-regulation of TLR9 response was observed in F4/80+CD11b+ and F4/80lowCD11b+ populations that correlated with the decreased TLR9 expression level in these cells. Interestingly, these cells recovered their capacity to respond to TLR9 agonist when MHCII+CD11chigh cells were impeded from producing IL-12/IL-23p40, thereby indicating possible cross-talk between these populations. The differential use of TLR2 and TLR9 by the immune cells during the acute phase of the infection explains why TLR9- but not TLR2-deficient mice are susceptible to T. cruzi infection

The emergence of pathogenic TNF/iNOS producing dendritic cells (Tip-DCs) in a malaria model of acute respiratory distress syndrome (ARDS) is dependent on CCR4

Malaria-associated acute respiratory distress syndrome (MA-ARDS) and acute lung injury (ALI) are complications that cause lung damage and often leads to death. The MA-ARDS/ALI is associated with a Type 1 inflammatory response mediated by T lymphocytes and IFN-gamma. Here, we used the Plasmodium berghei NK65 (PbN)-induced MA-ALI/ARDS model that resembles human disease and confirmed that lung CD4(+) and CD8(+) T cells predominantly expressed Tbet and IFN-gamma. Surprisingly, we found that development of MA-ALI/ARDS was dependent on functional CCR4, known to mediate the recruitment of Th2 lymphocytes and regulatory T cells. However, in this Type 1 inflammation-ARDS model, CCR4 was not involved in the recruitment of T lymphocytes, but was required for the emergence of TNF-alpha/iNOS producing dendritic cells (Tip-DCs) in the lungs. In contrast, recruitment of Tip-DCs and development of MA-ALI/ARDS were not altered in CCR2(-/)(-) mice. Importantly, we showed that NOS2(-/)(-) mice are resistant to PbN-induced lung damage, indicating that reactive nitrogen species produced by Tip-DCs play an essential role in inducing MA-ARDS/ALI. Lastly, our experiments suggest that production of IFN-gamma primarily by CD8(+) T cells is required for inducing Tip-DCs differentiation in the lungs and the development of MA-ALI/ARDS model

IL-10 limits parasite burden and protects against fatal myocarditis in a mouse model of Trypanosoma cruzi infection

Submitted by Nuzia Santos ([email protected]) on 2014-06-27T14:20:48Z No. of bitstreams: 1 . IL-10 limits parasite burden and protects against fatal myocarditis in a mouse model of Trypanosoma cruzi infection.pdf: 3474938 bytes, checksum: 16f33c5b8d642f9e9a7a13a95c91ca39 (MD5)Made available in DSpace on 2014-06-27T14:20:48Z (GMT). No. of bitstreams: 1 . IL-10 limits parasite burden and protects against fatal myocarditis in a mouse model of Trypanosoma cruzi infection.pdf: 3474938 bytes, checksum: 16f33c5b8d642f9e9a7a13a95c91ca39 (MD5) Previous issue date: 2012National Institutes of Health. National Institute of Allergy and Infectious Diseases. Laboratory of Molecular Immunology. Molecular Signaling Section. Bethesda, MD, USANational Institute of Allergy and Infectious Diseases. Laboratory of Parasitic Diseases. Immunobiology Section. Bethesda, MD, USA/Karolinska Institutet. Department of Microbiology. Tumor and Cell Biology. Stockholm, SwedenNational Institute of Allergy and Infectious Diseases. Laboratory of Parasitic Diseases. Helminth Immunology Section. Bethesda, MD, USANational Institutes of Health. National Institute of Allergy and Infectious Diseases. Laboratory of Molecular Immunology. Molecular Signaling Section. Bethesda, MD, USANational Institute of Allergy and Infectious Diseases. Laboratory of Parasitic Diseases. Intracellular Parasite Biology Section. Bethesda, MD, USANational Institute of Allergy and Infectious Diseases. O Office of the Director. ffice of Research Services. Division of Veterinary Resources. Bethesda, MD, USANational Institute of Allergy and Infectious Diseases. Laboratory of Parasitic Diseases. Immunobiology Section. Bethesda, MD, USA/Fundação Oswaldo Cruz. Centro de Pesquisas René Rachou. Laboratório de Imunopatologia. Belo Horizonte, MG, BrazilNational Institutes of Health. National Institute of Allergy and Infectious Diseases. Laboratory of Molecular Immunology. Molecular Signaling Section. Bethesda, MD, USAChagas' disease is a zoonosis prevalent in Latin America that is caused by the protozoan Trypanosoma cruzi. The immunopathogenesis of cardiomyopathy, the main clinical problem in Chagas' disease, has been extensively studied but is still poorly understood. In this study, we systematically compared clinical, microbiologic, pathologic, immunologic, and molecular parameters in two mouse models with opposite susceptibility to acute myocarditis caused by the myotropic Colombiana strain of T. cruzi: C3H/HeSnJ (100% mortality, uncontrolled parasitism) and C57BL/6J (<10% mortality, controlled parasitism). T. cruzi induced differential polarization of immunoregulatory cytokine mRNA expression in the hearts of C57BL/6J versus C3H/HeSnJ mice; however, most differences were small. The difference in IL-10 expression was exceptional (C57BL/6J 8.7-fold greater than C3H/HeSnJ). Consistent with this, hearts from infected C57BL/6J mice, but not C3H/HeSnJ mice, had a high frequency of total IL-10-producing CD8(+) T cells and both CD4(+) and CD8(+) subsets of IFN-γ(+)IL-10(+) double-producing T cells. Furthermore, T. cruzi infection of IL-10(-/-) C57BL/6J mice phenocopied fatal infection in wild-type C3H/HeSnJ mice with complete loss of parasite control. Adoptive transfer experiments indicated that T cells were a source of protective IL-10. Thus, in this system, IL-10 production by T cells promotes T. cruzi control and protection from fatal acute myocarditis

Type I Interferon Transcriptional Signature in Neutrophils and Low-Density Granulocytes Are Associated with Tissue Damage in Malaria

Neutrophils are the most abundant leukocyte population in the bloodstream, the primary compartment of Plasmodium sp. infection. However, the role of these polymorphonuclear cells in mediating either the resistance or the pathogenesis of malaria is poorly understood. We report that circulating neutrophils from malaria patients are highly activated, as indicated by a strong type I interferon transcriptional signature, increased expression of surface activation markers, enhanced release of reactive oxygen species and myeloperoxidase, and a high frequency of low-density granulocytes. The activation of neutrophils was associated with increased levels of serum alanine and aspartate aminotransferases, indicating liver damage. In a rodent malaria model, we observed intense recruitment of neutrophils to liver sinusoids. Neutrophil migration and IL-1β and chemokine expression as well as liver damage were all dependent on type I interferon signaling. The data suggest that type I interferon signaling has a central role in neutrophil activation and malaria pathogenesis.status: publishe

Trypanosoma cruzi-Induced Activation of Functionally Distinct αβ and γδ CD4− CD8− T Cells in Individuals with Polar Forms of Chagas' Disease ▿

CD4− CD8− (double-negative [DN]) T cells have recently been shown to display important immunological functions in human diseases. They express γδ or αβ T-cell receptors that recognize lipid/glycolipid antigens presented via the nonclassical major histocompatibility complex molecules of the CD1 family. We recently demonstrated that while αβ DN T cells serve primarily to express inflammatory cytokines, γδ DN T cells express mainly interleukin-10 (IL-10) in patients with cutaneous leishmaniasis. We also demonstrated a correlation between DN T cells and the expression of gamma interferon in the acute phase of Trypanosoma cruzi experimental infection. In this work, we sought to investigate whether αβ or γδ DN T cells display distinct immunoregulatory potentials in patients with polar forms of human Chagas' disease. Our data showed that in vitro infection with T. cruzi leads to expansion of DN T cells in patients with the indeterminate and severe cardiac clinical forms of the disease. However, while αβ DN T cells primarily produce inflammatory cytokines in both forms of the disease, γδ DN T cells display a marked, significant increase in antigen-specific IL-10 expression in indeterminate patients relative to cardiac patients. Finally, higher frequencies of the IL-10-producing γδ DN T cells were correlated with improved clinical measures of cardiac function in the patients, suggesting a protective role for these cells in Chagas' disease. Taken together, these data show distinct functional characteristics for αβ and γδ DN T cells associated with distinct morbidity rates and clinical forms in human Chagas' disease