Multifunctional, TNF-α and IFN-γ-Secreting CD4 and CD8 T Cells and CD8High T Cells Are Associated With the Cure of Human Visceral Leishmaniasis.

Visceral leishmaniasis (VL) is a chronic and often fatal disease caused by protozoans of the genus Leishmania that affects millions of people worldwide. Patients with symptomatic VL have an impaired anti-Leishmania-specific CD4+ T-cell response, which is reversed after clinical cure. In contrast, the quality of the CD4+ and CD8+ T-cell responses involved in resistance and/or cure of VL relies on the capability of these cells to activate polyfunctional and memory responses, which are associated with the simultaneous production of three cytokines: IFN-γ, IL-2, and TNF-α. Models for the development of CD4 and CD8 T-cell quality in memory and protection to leishmaniasis have been described previously. We aimed to assess the functionality of the T cells involved in the recovery of the immune suppression throughout the VL treatment. Therefore, we cultured peripheral blood mononuclear cells (PBMCs) from VL patients and healthy controls in vitro with soluble Leishmania antigen (SLA). Cell surface markers and intracellular cytokine production were determined on days 7, 14, 21, 30, 60, 90, and 180 after the beginning of chemotherapy. We observed that the frequencies of CD4+TNF-α+IFN-γ+ and the multifunctional CD4+IL-2+TNF-α+IFN-γ+, together with CD4+TNF-α+ and CD4+IFN-γ+ T cells, increased throughout and at the end of the treatment, respectively. In addition, enhanced frequencies of CD8+IL-2+TNF-α+IFN-γ+ and CD8+TNF-α+IFN-γ T cells were also relevant in the healing process. Noteworthy, the frequencies of the CD4+ and CD8 central-memory T cells, which produce IL-2, TNF-α, and IFN-γ and ensure the memory response against parasite reinfection, are significantly enhanced in cured patients. In addition, the subset of the non-functional CD8Low population is predominant in VL untreated patients and decreases along the chemotherapy treatment. In contrast, a CD8High subset increased towards the cure. Furthermore, the cure due to treatment with meglumine antimoniate or with liposomal amphotericin B was associated with the recovery of the T-cell immune responses. We described the evolution and participation of functional T cells during the treatment of patients with VL. Our results disclosed that the clinical improvement of patients is significantly associated with the participation of the CD4+ and CD8+ cytokine-secreting T cells.

Mycobacterium leprae Recombinant Antigen Induces High Expression of Multifunction T Lymphocytes and Is Promising as a Specific Vaccine for Leprosy.

Leprosy is a chronic disease caused by M. leprae infection that can cause severe neurological complications and physical disabilities. A leprosy-specific vaccine would be an important component within control programs but is still lacking. Given that multifunctional CD4 T cells [i.e., those capable of simultaneously secreting combinations of interferon (IFN)-γ, interleukin (IL)-2, and tumor necrosis factor (TNF)] have now been implicated in the protective response to several infections, we tested the hypothesis if a recombinant M. leprae antigen-specific multifunctional T cells differed between leprosy patients and their healthy contacts. We used whole blood assays and peripheral blood mononuclear cells to characterize the antigen-specific T cell responses of 39 paucibacillary (PB) and 17 multibacillary (MB) leprosy patients and 31 healthy household contacts (HHC). Cells were incubated with either crude mycobacterial extracts (M. leprae cell sonicate-MLCS) and purified protein derivative (PPD) or recombinant ML2028 protein, the homolog of M. tuberculosis Ag85B. Multiplex assay revealed antigen-specific production of IFN-γ and IL-2 from cells of HHC and PB, confirming a Th1 bias within these individuals. Multiparameter flow cytometry then revealed that the population of multifunctional ML2028-specific T cells observed in HHC was larger than that observed in PB patients. Taken together, our data suggest that these multifunctional antigen-specific T cells provide a more effective response against M. leprae infection that prevents the development of leprosy. These data further our understanding of M. leprae infection/leprosy and are instructive for vaccine development.

Spatial analysis of viral hepatitis and schistosomiasis coinfection in an endemic area in Northeastern Brazil

Abstract INTRODUCTION: This cross-sectional study analyzed the spatial distribution of hepatitis B or C virus (HBV/HBC) and schistosomiasis coinfection. METHODS: Serum samples were collected from patients with Schistosoma mansoni infection. These were tested for serological markers of HBV/HCV infection. The spatial distribution of coinfection was analyzed using intensity kernel estimation. RESULTS: Overall, 9.4% of individuals had contact with HBV and 1.7% of samples tested positive for anti-HCV antibodies. We identified clusters of risk located in the central region. CONCLUSIONS: Spatial analysis allowed visualization of high-risk areas, leading to a definition of priority areas to be targeted for intensification of control interventions.

RIPK1 and PGAM5 Control Leishmania Replication through Distinct Mechanisms.

Leishmaniasis is an important parasitic disease found in the tropics and subtropics. Cutaneous and visceral leishmaniasis affect an estimated 1.5 million people worldwide. Despite its human health relevance, relatively little is known about the cell death pathways that control Leishmania replication in the host. Necroptosis is a recently identified form of cell death with potent antiviral effects. Receptor interacting protein kinase 1 (RIPK1) is a critical kinase that mediates necroptosis downstream of death receptors and TLRs. Heme, a product of hemoglobin catabolism during certain intracellular pathogen infections, is also a potent inducer of macrophage necroptosis. We found that human visceral leishmaniasis patients exhibit elevated serum levels of heme. Therefore, we examined the impact of heme and necroptosis on Leishmania replication. Indeed, heme potently inhibited Leishmania replication in bone marrow-derived macrophages. Moreover, we found that inhibition of RIPK1 kinase activity also enhanced parasite replication in the absence of heme. We further found that the mitochondrial phosphatase phosphoglycerate mutase family member 5 (PGAM5), a putative downstream effector of RIPK1, was also required for inhibition of Leishmania replication. In mouse infection, both PGAM5 and RIPK1 kinase activity are required for IL-1ß expression in response to Leishmania However, PGAM5, but not RIPK1 kinase activity, was directly responsible for Leishmania-induced IL-1ß secretion and NO production in bone marrow-derived macrophages. Collectively, these results revealed that RIPK1 and PGAM5 function independently to exert optimal control of Leishmania replication in the host.

Análise espacial e características epidemiológicas dos casos de esquistossomose mansônica no município de Simão Dias, nordeste do Brasil / Spatial analysis and epidemiological characteristics of cases of schistosomiasis in the municipality of Simão Dias, northeast of Brazil

O objetivo deste estudo foi analisar a distribuição espacial e as características epidemiológicas da esquistossomose mansônica no município de Simão Dias, Sergipe, Brasil. Trata-se de um estudo epidemiológico, descritivo e transversal. Para o inquérito coproscópico, examinou-se o material fecal de 3.472 amostras no ano de 2011. Os casos positivos de Schistosoma mansoni foram georreferenciados utilizando-se o método absoluto com posicionamento instantâneo de um ponto e com auxílio de um receptor GPS para a localização espacial dos domicílios onde existiam casos de esquistossomose. Para a análise espacial dos dados e identificação visual de padrões de distribuição e densidade dos casos, foi adotado o estimador de Kernel, sendo as análises realizadas pelo software TerraView, versão 4.2.0. O município de Simão Dias é uma área de baixa endemicidade da esquistossomose, visto que apresentou prevalência de 4,3%. Os indivíduos mais acometidos pela infecção foram os do sexo masculino, na faixa etária de 10 a 39 anos, de etnia parda, solteiros e com renda familiar de 1 a 2 salários mínimos. A análise espacial, com base no estimador de densidade de Kernel, permitiu a construção de mapas que apontaram a existência de três regiões de risco para transmissão da esquistossomose: Pau de Leite, Açude e Curral dos Bois. Apesar dos inquéritos evidenciarem a ocorrência de esquistossomose, ainda se desconhecem medidas preventivas eficientes para a redução desse agravo implementadas na região. As técnicas de análise espacial empregadas configuram-se como um importante método para o monitoramento e controle desta doença parasitária

Soluble CD40 Ligand in Sera of Subjects Exposed to Leishmania infantum Infection Reduces the Parasite Load in Macrophages.

BACKGROUND: While CD40L is typically a membrane glycoprotein expressed on activated T cells and platelets that binds and activates CD40 on the surface on antigen presenting cells, a soluble derivative (sCD40L) that appears to retain its biological activity after cleavage from cell membrane also exists. We recently reported that sCD40L is associated with clinical resolution of visceral leishmaniasis and protection against the disease. In the present study we investigated if this sCD40L is functional and exerts anti-parasitic effect in L. infantum-infected macrophages. METHODOLOGY/PRINCIPAL FINDINGS: Macrophages from normal human donors were infected with L. infantum promastigotes and incubated with either sera from subjects exposed to L. infantum infection, monoclonal antibodies against human CD40L, or an isotype control antibody. We then evaluated infection by counting the number of infected cells and the number of parasites in each cell. We also measured a variety of immune modulatory cytokines in these macrophage culture supernatants by Luminex assay. The addition of sCD40L, either recombinant or from infected individuals' serum, decreased both the number of infected macrophages and number of intracellular parasites. Moreover, this treatment increased the production of IL-12, IL-23, IL-27, IL-15, and IL1ß such that negative correlations between the levels of these cytokines with both the infection ratio and number of intracellular parasites were observed. CONCLUSIONS/SIGNIFICANCE: sCD40L from sera of subjects exposed to L. infantum is functional and improves both the control of parasite and production of inflamatory cytokines of infected macrophages. Although the mechanisms involved in parasite killing are still unclear and require further exploration, these findings indicate a protective role of sCD40L in visceral leishmaniasis.