Exposure of Phosphatidylserine on Leishmania amazonensis Isolates Is Associated with Diffuse Cutaneous Leishmaniasis and Parasite Infectivity

Diffuse cutaneous leishmaniasis (DCL) is a rare clinical manifestation of leishmaniasis, characterized by an inefficient parasite-specific cellular response and heavily parasitized macrophages. In Brazil, Leishmania (Leishmania) amazonensis is the main species involved in DCL cases. In the experimental model, recognition of phosphatidylserine (PS) molecules exposed on the surface of amastigotes forms of L. amazonensis inhibits the inflammatory response of infected macrophages as a strategy to evade the host immune surveillance. In this study, we examined whether PS exposure on L. amazonensis isolates from DCL patients operated as a parasite pathogenic factor and as a putative suppression mechanism of immune response during the infection. Peritoneal macrophages from F1 mice (BALB/c×C57BL/6) were infected with different L. amazonensis isolates from patients with localized cutaneous leishmaniasis (LCL) or DCL. DCL isolates showed higher PS exposure than their counterparts from LCL patients. In addition, PS exposure was positively correlated with clinical parameters of the human infection (number of lesions and time of disease) and with characteristics of the experimental infection (macrophage infection and anti-inflammatory cytokine induction). Furthermore, parasites isolated from DCL patients displayed an increased area in parasitophorous vacuoles (PV) when compared to those isolated from LCL patients. Thus, this study shows for the first time that a parasite factor (exposed PS) might be associated with parasite survival/persistence in macrophages and lesion exacerbation during the course of DCL, providing new insights regarding pathogenic mechanism in this rare chronic disease

Cooperation between Apoptotic and Viable Metacyclics Enhances the Pathogenesis of Leishmaniasis

Mimicking mammalian apoptotic cells by exposing phosphatidylserine (PS) is a strategy used by virus and parasitic protozoa to escape host protective inflammatory responses. With Leishmania amazonensis (La), apoptotic mimicry is a prerogative of the intramacrophagic amastigote form of the parasite and is modulated by the host. Now we show that differently from what happens with amastigotes, promastigotes exposing PS are non-viable, non-infective cells, undergoing apoptotic death. As part of the normal metacyclogenic process occurring in axenic cultures and in the gut of sand fly vectors, a sub-population of metacyclic promastigotes exposes PS. Apoptotic death of the purified PS-positive (PSPOS) sub-population was confirmed by TUNEL staining and DNA laddering. Transmission electron microscopy revealed morphological alterations in PSPOS metacyclics such as DNA condensation, cytoplasm degradation and mitochondrion and kinetoplast destruction, both in in vitro cultures and in sand fly guts. TUNELPOS promastigotes were detected only in the anterior midgut to foregut boundary of infected sand flies. Interestingly, caspase inhibitors modulated parasite death and PS exposure, when added to parasite cultures in a specific time window. Efficient in vitro macrophage infections and in vivo lesions only occur when PSPOS and PS-negative (PSNEG) parasites were simultaneously added to the cell culture or inoculated in the mammalian host. The viable PSNEG promastigote was the infective form, as shown by following the fate of fluorescently labeled parasites, while the PSPOS apoptotic sub-population inhibited host macrophage inflammatory response. PS exposure and macrophage inhibition by a subpopulation of promastigotes is a different mechanism than the one previously described with amastigotes, where the entire population exposes PS. Both mechanisms co-exist and play a role in the transmission and development of the disease in case of infection by La. Since both processes confer selective advantages to the infective microorganism they justify the occurrence of apoptotic features in a unicellular pathogen

Phosphatidylserine exposure on the surface of Leishmania amazonensis amastigotes modulates in vivo infection and dendritic cell function

Made available in DSpace on 2015-08-19T13:49:41Z (GMT). No. of bitstreams: 2 license.txt: 1914 bytes, checksum: 7d48279ffeed55da8dfe2f8e81f3b81f (MD5) marcelo_marcinski2_etal_IOC-2013.pdf: 2808095 bytes, checksum: edcdb98bfead0b5ab32e449b0789faf4 (MD5) Previous issue date: 2013Universidade Federal do Rio de Janeiro. Instituto de Ciências Biomédicas. Programa de Ciências Morfológicas. Rio de Janeiro, RJ, Brasil / Universidade Federal do Rio de Janeiro. Campus UFRJ Macaé. Pólo Universitário, Macaé, RJ, Brasil / University of Texas Medical Branch. Institute for Human Infections and Immunity. 3Department of Microbiology and Immunology. Galveston, TX, USA.University of Texas Southwestern Medical Center. Department of Pharmacology. Dallas, TX, USA.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Biologia Celular. Rio de Janeiro, RJ, Brasil / Universidade de São Paulo. Instituto de Ciências Biomédicas. Departamento de Parasitologia.São Paulo, SP, Brasil.University of Texas Southwestern Medical Center. Department of Pharmacology. Sealy Center for Vaccine Development. Center for Biodefense and Emerging Infectious Diseases. 7Department of Pathology. Dallas, TX, USA /Leishmania amazonensis parasites can cause diverse forms of leishmaniasis in humans and persistent lesions in most inbred strains of mice. In both cases, the infection is characterized by a marked immunosuppression of the host. We previously showed that amastigote forms of the parasite make use of surface-exposed phosphatidylserine (PS) molecules to infect host cells and promote alternative macrophage activation, leading to uncontrolled intracellular proliferation of the parasites. In this study, we demonstrated that treatment of infected mice with an PS-targeting monoclonal antibody ameliorated parasite loads and lesion development, which correlated with increased proliferative responses by lymphocytes. In addition, we observed an enhanced dendritic cell (DC) activation and antigen presentation in vitro. Our data imply that the recognition of PS exposed on the surface of amastigotes plays a role in down-modulating DC functions, in a matter similar to that of apoptotic cell clearance. This study provides new information regarding the mechanism of immune suppression in Leishmania infection

Apoptosis and apoptotic mimicry in Leishmania: an evolutionary perspective

Submitted by Ana Maria Fiscina Sampaio ([email protected]) on 2015-02-11T12:11:12Z No. of bitstreams: 1 El-Hani CN Apoptosis....pdf: 356580 bytes, checksum: 3f6b4ac466b009c2fcb8dd839a7bc952 (MD5)Approved for entry into archive by Ana Maria Fiscina Sampaio ([email protected]) on 2015-02-11T12:11:23Z (GMT) No. of bitstreams: 1 El-Hani CN Apoptosis....pdf: 356580 bytes, checksum: 3f6b4ac466b009c2fcb8dd839a7bc952 (MD5)Approved for entry into archive by Ana Maria Fiscina Sampaio ([email protected]) on 2015-02-11T12:29:31Z (GMT) No. of bitstreams: 1 El-Hani CN Apoptosis....pdf: 356580 bytes, checksum: 3f6b4ac466b009c2fcb8dd839a7bc952 (MD5)Made available in DSpace on 2015-02-11T12:29:31Z (GMT). No. of bitstreams: 1 El-Hani CN Apoptosis....pdf: 356580 bytes, checksum: 3f6b4ac466b009c2fcb8dd839a7bc952 (MD5) Previous issue date: 2012Universidade Federal da Bahia. Instituto de Biologia. Laboratório de Ensino, História e Filosofia de Biologia. Salvador, BA, Brasil.Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / Universidade Federal da Bahia. Faculdade de Medicina. Salvador, BA, Brasil / Instituto Nacional de Ciência e Tecnologia de Investigação em Imunologia. Salvador, BA, Brasil.Universidade Federal do Rio de Janeiro. Pólo Universitário Macaé. Macaé, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Biologia Celular. Rio de Janeiro, RJ, Brasil.Apoptotic death and apoptotic mimicry are defined respectively as a non-accidental death and as the mimicking of an apoptotic-cell phenotype, usually by phosphatidylserine (PS) exposure. In the case of the murine infection by Leishmania spp, apoptotic death has been described in promastigotes and apoptotic mimicry in amastigotes. In both situations they are important events of the experimental murine infection by this parasite. In the present review we discuss what features we need to consider if we want to establish if a behavior shown by Leishmania is altruistic or not: does the behavior increases the fitness of organisms other than the one showing it? Does this behavior have a cost for the actor? If we manage to show that a given behavior is costly for the actor and beneficial for the recipient of the action, we will be able to establish it as altruistic. From this perspective, we can argue that apoptotic-like death and apoptotic mimicry are both altruistic with the latter representing a weaker altruistic behavior than the former

Leishmaniasis and glycosaminoglycans: a future therapeutic strategy?

Abstract Leishmania spp. depend on effective macrophage infection to establish and develop in mammalian hosts. Both metacyclic promastigotes and amastigotes are able to infect host cells, and thus they rely on several ligands that, when recognized by macrophage receptors, mediate parasite uptake. During macrophage primary infection with metacyclic forms from the insect vector and during amastigote dissemination via macrophage rupture, both infective stages have to cope with the host extracellular microenvironment, including extracellular matrix molecules. Glycosaminoglycans are abundant in the extracellular matrix and many of these molecules are able to interact with the parasite and the host cell, mediating positive and negative effects for the infection, depending on their structure and/or location. In addition, glycosaminoglycans are present at the surface of macrophages as proteoglycans, playing important roles for parasite recognition and uptake. In this review, we discuss glycosaminoglycans in the context of Leishmania infection as well as the possible applications of the current knowledge regarding these molecules for the development of new therapeutic strategies to control parasite dissemination

Apoptosis and apoptotic mimicry in Leishmania: an evolutionary perspective

Apoptotic death and apoptotic mimicry are defined respectively as a non-accidental death and as the mimicking of an apoptotic-cell phenotype, usually by phosphatidylserine exposure. In the case of the murine infection by Leishmania spp, apoptotic death has been described in promastigotes and apoptotic mimicry in amastigotes. In both situations they are important events of the experimental murine infection by this parasite. In the present review we discuss what features we need to consider if we want to establish if a behavior shown by Leishmania is altruistic or not: does the behavior increases the fitness of organisms other than the one showing it? Does this behavior have a cost for the actor? If we manage to show that a given behavior is costly for the actor and beneficial for the recipient of the action, we will be able to establish it as altruistic. From this perspective, we can argue that apoptotic-like death and apoptotic mimicry are both altruistic with the latter representing a weaker altruistic behavior than the former

ApoptoticC mimicry as a possible immunopatogenic mechanism of Diffuse Cutaneous Leishmaniasis (DCL)

Submitted by Ana Maria Fiscina Sampaio ([email protected]) on 2015-03-20T18:40:17Z No. of bitstreams: 1 Costa JF Mimetismo apoptotico....pdf: 68324 bytes, checksum: 33661a663a7476ce1baf04785c2a5724 (MD5)Approved for entry into archive by Ana Maria Fiscina Sampaio ([email protected]) on 2015-03-20T18:55:21Z (GMT) No. of bitstreams: 1 Costa JF Mimetismo apoptotico....pdf: 68324 bytes, checksum: 33661a663a7476ce1baf04785c2a5724 (MD5)Made available in DSpace on 2015-03-20T18:55:21Z (GMT). No. of bitstreams: 1 Costa JF Mimetismo apoptotico....pdf: 68324 bytes, checksum: 33661a663a7476ce1baf04785c2a5724 (MD5) Previous issue date: 2009Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, BrasilInstituto Nacional do Câncer. Divisão de Medicina Experimental. Rio de Janeiro, RJ / Universidade Federal do Rio de Janeiro. Instituto de Ciências Biomédicas. Rio de Janeiro, RJ, BrasilFundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, BrasilInstituto Nacional do Câncer. Divisão de Medicina Experimental. Rio de Janeiro, RJ / Universidade de São Paulo. Instituto de Ciências Biomédicas. Departamento de Parasitologia. São Paulo, SP, BrasilFundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / Universidade Federal da Bahia. Faculdade de Medicina. Salvador, BA, Brasil / Instituto de Investigação em Imunologia. INCT. Salvador, BA, BrasilFundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Salvador, BA, Brasil / Instituto de Investigação em Imunologia. INCT. Salvador, BA, BrasilA Leishmaniose Cutânea Difusa (LCD) é uma manifestação clínica rara das leishmanioses, caracterizada pela presença de inúmeros macrófagos intensamente parasitados. Tem sido sugerido que a LCD resulta da ausência de resposta imune celular a antígenos de Leishmania, levando ao crescimento descontrolado do parasita. No Brasil, a LCD é quase que exclusivamente causada pela Leishmania (Leishmania) amazonensis. Nessa revisão discutiremos o papel da morte celular programada por apoptose como possível mecanismo imunopatogênico na infecção por L. amazonensis. Semelhante ao que ocorre durante o reconhecimento e fagocitose de células apoptóticas, formas amastigotas de L. amazonensis expõem PS em sua superfície, em um mecanismo chamado “Mimetismo Apoptótico” que resulta na desativação do macrófago e possibilita o estabelecimento e manutenção da infecção. Nesse contexto, o estudo da exposição de PS nos isolados de L. amazonensis de pacientes com LCD pode contribuir na elucidação de mecanismos supressores nessa patologiaDiffuse Cutaneous Leishmaniasis (DCL) is a rare clinical manifestation of Leishmaniasis, characterized by a number of macrophages heavily parasitized. It has been suggested that DCL results from a lack of cell-mediated immunity to leishmanial antigen, leading to uncontrolled parasite growth. In Brazil, Leishmania (Leishmania) amazonensis is the main specie involved in DCL cases. In this review we approached the role of programmed cell death by apoptosis as a possible immunopathogenic mechanism in the L. amazonensis infection. Similarly to the exposure and recognition of apoptotic cells, L. amazonensis amastigotes expose PS on its surface, in a mechanism called “Apoptotic Mimicry” which drives macrophage deactivation and allows the infection establishment and maintenance. In this context, the study of PS exposure in the isolates of L. amazonensis of patients with DCL may contribute in the elucidation of suppressor mechanisms in this pathology