DETC Induces Leishmania Parasite Killing in Human In Vitro and Murine In Vivo Models: A Promising Therapeutic Alternative in Leishmaniasis

Background: Chemotherapy remains the primary tool for treatment and control of human leishmaniasis. However, currently available drugs present serious problems regarding side-effects, variable efficacy, and cost. Affordable and less toxic drugs are urgently needed for leishmaniasis. Methodology/Principal Findings: We demonstrate, by microscopy and viability assays, that superoxide dismutase inhibitor diethyldithiocarbamate (DETC) dose-dependently induces parasite killing (p,0.001) and is able to ??????sterilize?????? Leishmania amazonensis infection at 2 mM in human macrophages in vitro. We also show that DETC-induced superoxide production (p,0.001) and parasite destruction (p,0.05) were reverted by the addition of the antioxidant N-acetylcysteine, indicating that DETC-induced killing occurs through oxidative damage. Furthermore, ultrastructural analysis by electron microscopy demonstrates a rapid and highly selective destruction of amastigotes in the phagosome upon DETC treatment, without any apparent damage to the host cell, including its mitochondria. In addition, DETC significantly induced parasite killing in Leishmania promastigotes in axenic culture. In murine macrophages infected with Leishmania braziliensis, DETC significantly induced in vitro superoxide production (p = 0.0049) and parasite killing (p = 0.0043). In vivo treatment with DETC in BALB/C mice infected with Leishmania braziliensis caused a significant decrease in lesion size (p,0.0001), paralleled by a 100-fold decrease (p = 0.0087) in parasite burden. Conclusions/Significance: Due to its strong leishmanicidal effect in human macrophages in vitro, its in vivo effectiveness in a murine model, and its previously demonstrated in vivo safety profile in HIV treatment, DETC treatment might be considered as a valuable therapeutic option in human leishmaniasis, including HIV/Leishmania co-infection

Immunity to Lutzomyia intermedia Saliva Modulates the Inflammatory Environment Induced by Leishmania braziliensis

Transmission of Leishmania parasites occurs during blood feeding, when infected female sand flies inject humans with parasites and saliva. Chemokines and cytokines are secreted proteins that regulate the initial immune responses and have the potential of attracting and activating cells. Herein, we studied the expression of such molecules and the cellular recruitment induced by salivary proteins of the Lutzomyia intermedia sand fly. Of note, Lutzomyia intermedia is the main vector of Leishmania braziliensis, a parasite species that causes cutaneous leishmaniasis, a disease associated with the development of destructive skin lesions that can be fatal if left untreated. We observed that L. intermedia salivary proteins induce a potent cellular recruitment and modify the expression profile of chemokines and cytokines in mice. More importantly, in mice previously immunized with L. intermedia saliva, the alteration in the initial inflammatory response was even more pronounced, in terms of the number of cells recruited and in terms of gene expression pattern. These findings indicate that an existing immunity to L. intermedia sand fly induces an important modulation in the initial immune response that may, in turn, promote parasite multiplication, leading to the development of cutaneous leishmaniasis

BluePort: A Platform to Study the Eosinophilic Response of Mice to the Bite of a Vector of Leishmania Parasites, Lutzomyia longipalpis Sand Flies

transmission in residents of endemic areas has been attributed to the acquisition of immunity to sand fly salivary proteins. One theoretical way to accelerate the acquisition of this immunity is to increase the density of antigen-presenting cells at the sand fly bite site. Here we describe a novel tissue platform that can be used for this purpose. sand flies. Results presented indicate that a shift in the inflammatory response, from neutrophilic to eosinophilic, is the main histopathological feature associated with the immunity acquired through repeated exposure to the bite of sand flies, and that the BluePort tissue compartment could be used to accelerate this process. In addition, changes observed inside the BluePort parenchyma indicate that it could be used to study complex immunobiological processes, and to develop ectopic secondary lymphoid structures.Understanding the characteristics of the dermal response to the bite of sand flies is a critical element of strategies to control leishmaniasis using vaccines that target salivary proteins. Finding that dermal eosinophilia is such a prominent component of the anti-salivary immunity induced by repeated exposure to sand fly bites raises one important consideration: how to avoid the immunological conflict derived from a protective Th2-driven immunity directed to sand fly saliva with a protective Th1-driven immunity directed to the parasite. The BluePort platform is an ideal tool to address experimentally this conundrum

Regulation of immunity during visceral Leishmania infection

Unicellular eukaryotes of the genus Leishmania are collectively responsible for a heterogeneous group of diseases known as leishmaniasis. The visceral form of leishmaniasis, caused by L. donovani or L. infantum, is a devastating condition, claiming 20,000 to 40,000 lives annually, with particular incidence in some of the poorest regions of the world. Immunity to Leishmania depends on the development of protective type I immune responses capable of activating infected phagocytes to kill intracellular amastigotes. However, despite the induction of protective responses, disease progresses due to a multitude of factors that impede an optimal response. These include the action of suppressive cytokines, exhaustion of specific T cells, loss of lymphoid tissue architecture and a defective humoral response. We will review how these responses are orchestrated during the course of infection, including both early and chronic stages, focusing on the spleen and the liver, which are the main target organs of visceral Leishmania in the host. A comprehensive understanding of the immune events that occur during visceral Leishmania infection is crucial for the implementation of immunotherapeutic approaches that complement the current anti-Leishmania chemotherapy and the development of effective vaccines to prevent disease.The research leading to these results has received funding from the European Community’s Seventh Framework Programme under grant agreement No.602773 (Project KINDRED). VR is supported by a post-doctoral fellowship granted by the KINDReD consortium. RS thanks the Foundation for Science and Technology (FCT) for an Investigator Grant (IF/00021/2014). This work was supported by grants to JE from ANR (LEISH-APO, France), Partenariat Hubert Curien (PHC) (program Volubilis, MA/11/262). JE acknowledges the support of the Canada Research Chair Program

Histoplasmose pulmonar aguda no Rio Grande do Sul Acute pulmonary histoplasmosis in the State of Rio Grande do Sul, Brazil

INTRODUÇÃO: A histoplasmose pulmonar aguda depende da inalação de uma grande quantidade de propágulos fúngicos por um paciente hígido. O tempo de exposição determina a gravidade da doença. Uma epidemia é influenciada por fatores que afetam o crescimento e a transmissão do Histoplasma capsulatum var. capsulatum na natureza. OBJETIVO: Identificar os aspectos epidemiológicos e clínico-laboratoriais dos pacientes com histoplasmose pulmonar aguda no Rio Grande do Sul e compará-los com as microepidemias relatadas no Brasil. MÉTODO: Foram revisados 212 prontuários clínicos de pacientes com histoplasmose dos arquivos do Laboratório de Micologia do Complexo Hospitalar Santa Casa de Porto Alegre (RS) num período de 25 anos (1977-2002). Foram identificados e incluídos no estudo os casos de histoplasmose pulmonar aguda com cultivo positivo e/ou achado histopatológico compatível. As microepidemias foram diagnosticadas com a comprovação de um caso ou evidência soromicológica com história clínica compatível. Foram revisadas as microepidemias publicadas no Brasil. RESULTADOS: Dezoito de um total de 212 pacientes (8,5%) foram incluídos no trabalho. A idade variou de 8 a 63 anos (média de 35,4; mediana de 34,5), e 67% eram do sexo masculino. A história epidemiológica foi sugestiva em 11 pacientes (61%). O tipo primário de histoplasmose pulmonar aguda foi o mais freqüente (17; 95%). Houve predomínio de casos isolados. CONCLUSÃO: O reconhecimento de casos isolados e a presença de microepidemias demonstram a abundância do H. capsulatum no solo, e juntamente com a ocorrência de todas as formas da doença, confirmam o Rio Grande do Sul como hiperendêmico para histoplasmose.<br>BACKGROUND: Acute pulmonary histoplasmosis is a respiratory infection occurring when an otherwise healthy individual inhales a large quantity of fungal propagules. Length of exposure determines disease severity. An epidemic is influenced by factors affecting the growth and transmission of Histoplasma capsulatum var. capsulatum in nature. OBJECTIVE: To identify epidemiological and clinical aspects of patients with acute pulmonary histoplasmosis in the state of Rio Grande do Sul (RS) and compare these aspects with those of other cluster outbreaks reported in Brazil. METHOD: The charts of 212 patients diagnosed with histoplasmosis over a 25-year period (1977-2002) were obtained from the archives of the Laboratório de Micologia from Complexo Hospitalar Santa Casa (Santa Casa Hospital Mycology Laboratory), in the city of Porto Alegre (RS). In reviewing these patient charts, we identified and included in the study cases of acute pulmonary histoplasmosis in which there was a positive culture and/or histopathological findings consistent with the diagnosis. Outbreaks were defined as one confirmed case or positive immunodifusion Histoplasma capsulatum with compatible clinical history. All reported Brazilian outbreaks were reviewed. RESULTS: Of the 212 patient charts reviewed, 18 (8.5%) were selected for inclusion in the study. Among those 18 patients, ages ranged from 8 to 63 years (median, 35.4), and 67% were male. Epidemiological histories were suggestive of the disease in 11 patients (61%). The most common disease type, seen in 17 patients (95%), was primary acute pulmonary histoplasmosis, and there was a predominance of isolated cases. CONCLUSION: The identification of isolated cases and the presence of cluster outbreaks demonstrate the abundance of H. capsulatum in the soil and, together with the occurrence of all forms of the disease, confirms the assumption that Rio Grande do Sul is a hyperendemic region for histoplasmosis