RESUMO
Pathological features observed in both human and experimental cerebral malaria (ECM) are endothelial dysfunction and changes in blood components. Blood transfusion has been routinely used in patients with severe malarial anemia and can also benefit comatose and acidotic malaria patients. In the present study Plasmodium berghei-infected mice were transfused intraperitoneally with 200 µL of whole blood along with 20 mg/kg of artemether. ECM mice showed severe thrombocytopenia and decreases in hematocrit. Artemether treatment markedly aggravated anemia within 24 h. Whole blood administration significantly prevented further drop in hematocrit and partially restored the platelet count. Increased levels of plasma angiopoietin-2 (Ang-2) remained high 24 h after artemether treatment but returned to normal levels 24 h after blood transfusion, indicating reversal to quiescence. Ang-1 was depleted in ECM mice and levels were not restored by any treatment. Blood transfusion prevented the aggravation of the breakdown of blood brain barrier after artemether treatment and decreased spleen congestion without affecting splenic lymphocyte populations. Critically, blood transfusion resulted in markedly improved survival of mice with ECM (75.9% compared to 50.9% receiving artemether only). These findings indicate that whole blood transfusion can be an effective adjuvant therapy for cerebral malaria.
Assuntos
Artemeter/farmacologia , Transfusão de Sangue , Malária Cerebral , Plasmodium berghei/metabolismo , Animais , Feminino , Malária Cerebral/sangue , Malária Cerebral/fisiopatologia , Malária Cerebral/terapia , CamundongosRESUMO
Detrimental effects of malnutrition on immune responses to pathogens have long been recognized and it is considered a main risk factor for various infectious diseases, including visceral leishmaniasis (VL). Thymus is a target of both malnutrition and infection, but its role in the immune response to Leishmania infantum in malnourished individuals is barely studied. Because we previously observed thymic atrophy and significant reduction in cellularity and chemokine levels in malnourished mice infected with L. infantum, we postulated that the thymic microenvironment is severely compromised in those animals. To test this, we analyzed the microarchitecture of the organ and measured the protein abundance in its interstitial space in malnourished BALB/c mice infected or not with L. infantum. Malnourished-infected animals exhibited a significant reduction of the thymic cortex:medulla ratio and altered abundance of proteins secreted in the thymic interstitial fluid. Eighty-one percent of identified proteins are secreted by exosomes and malnourished-infected mice showed significant decrease in exosomal proteins, suggesting that exosomal carrier system, and therefore intrathymic communication, is dysregulated in those animals. Malnourished-infected mice also exhibited a significant increase in the abundance of proteins involved in lipid metabolism and tricarboxylic acid cycle, suggestive of a non-proliferative microenvironment. Accordingly, flow cytometry analysis revealed decreased proliferation of single positive and double positive T cells in those animals. Together, the reduced cortical area, decreased proliferation, and altered protein abundance suggest a dysfunctional thymic microenvironment where T cell migration, proliferation, and maturation are compromised, contributing for the thymic atrophy observed in malnourished animals. All these alterations could affect the control of the local and systemic infection, resulting in an impaired response to L. infantum infection.
Assuntos
Interações Hospedeiro-Patógeno/imunologia , Leishmania infantum/imunologia , Leishmaniose Visceral/imunologia , Desnutrição/imunologia , Linfócitos T/imunologia , Timo/imunologia , Animais , Transporte Biológico , Movimento Celular , Proliferação de Células , Ciclo do Ácido Cítrico/genética , Ciclo do Ácido Cítrico/imunologia , Exossomos/imunologia , Exossomos/metabolismo , Exossomos/parasitologia , Líquido Extracelular/imunologia , Líquido Extracelular/metabolismo , Líquido Extracelular/parasitologia , Galectina 1/genética , Galectina 1/imunologia , Regulação da Expressão Gênica , Interações Hospedeiro-Patógeno/genética , Imunidade Inata , Leishmania infantum/crescimento & desenvolvimento , Leishmaniose Visceral/genética , Leishmaniose Visceral/metabolismo , Leishmaniose Visceral/parasitologia , Metabolismo dos Lipídeos , Masculino , Desnutrição/genética , Desnutrição/metabolismo , Desnutrição/parasitologia , Camundongos , Camundongos Endogâmicos BALB C , Plasminogênio/genética , Plasminogênio/imunologia , Proteoma/genética , Proteoma/imunologia , Linfócitos T/parasitologia , Timo/metabolismo , Timo/parasitologiaRESUMO
INTRODUCTION: The aim of the study was to investigate the role of the proteolytic fraction from Vasconcellea cundinamarcensis, designated as P1G10, on the healing of chronic foot ulcers in neuropathic patients with diabetes 2. METHODS: Fifty patients were enrolled in a prospective, randomized, double-blind trial, to verify the efficacy and safety of a topical dressing formulated with 0.1% P1G10, intended for wound healing, versus a hydrogel (control) protocol. Upon completion of the intervention, the outcome evaluated the number of patients attaining full epithelization (100%), or at least 80% healing. Statistical analysis compared the data on each group for the significance of the differences. RESULTS: Collection of data was finished in week 16, and the results were analyzed by intention to treat. The results showed that, in the control group, 5 patients attained 100% ulcer healing, 3 patients ≥ 80% healing and 11 experienced ulcer changes ≤ 80%, and the remainder showed no changes or their wounds became worse. Meanwhile, in the P1G10 group, 11 patients experienced full healing, 4 had healing ≥ 80% and 5 had ulcer changes ≤ lower than 80%, and the remainder showed no changes or their wounds became worse. The healing incidence for the first endpoint (100% healing) showed that the P1G10 group was 2.95-fold more efficacious than the control group (CI 95%) and 2.52-fold (CI, 95%) higher than its control for the second endpoint (80% healing). CONCLUSIONS: These data support the hypothesis that topical application of the proteolytic fraction identified as P1G10 significantly enhances foot ulcer healing compared to hydrogel treatment.
Assuntos
Caricaceae , Pé Diabético/terapia , Látex/uso terapêutico , Cicatrização/efeitos dos fármacos , Doença Crônica , Diabetes Mellitus Tipo 2/complicações , Pé Diabético/etiologia , Nefropatias Diabéticas/complicações , Método Duplo-Cego , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Estudos ProspectivosRESUMO
As key cells, able to host and kill Leishmania parasites, inflammatory monocytes/macrophages are potential vaccine and therapeutic targets to improve immune responses in Leishmaniasis. Macrophage phenotypes range from M1, which express NO-mediated microbial killing, to M2 macrophages that might help infection. Resistance to Leishmaniasis depends on Leishmania species, mouse strain, and both innate and adaptive immunity. C57BL/6 (B6) mice are resistant and control infection, whereas Leishmania parasites thrive in BALB/c mice, which are susceptible to develop cutaneous lesions in the course of infection with Leishmania major, but not upon infection with Leishmania braziliensis. Here, we investigated whether a deficit in early maturation of inflammatory monocytes into macrophages in BALB/c mice underlies increased susceptibility to L. major versus L. braziliensis parasites. We show that, after infection with L. braziliensis, monocytes are recruited to peritoneum, differentiate into macrophages, and develop an M1 phenotype able to produce proinflammatory cytokines in both B6 and BALB/c mice. Nonetheless, more mature macrophages from B6 mice expressed inducible NO synthase (iNOS) and higher NO production in response to L. braziliensis parasites, whereas BALB/c mice developed macrophages expressing an incomplete M1 phenotype. By contrast, monocytes recruited upon L. major infection gave rise to immature macrophages that failed to induce an M1 response in BALB/c mice. Overall, these results are consistent with the idea that resistance to Leishmania infection correlates with improved maturation of macrophages in a mouse-strain and Leishmania-species dependent manner. All-trans retinoic acid (ATRA) has been proposed as a therapy to differentiate immature myeloid cells into macrophages and help immunity to tumors. To prompt monocyte to macrophage maturation upon L. major infection, we treated B6 and BALB/c mice with ATRA. Unexpectedly, treatment with ATRA reduced proinflammatory cytokines, iNOS expression, and parasite killing by macrophages. Moreover, ATRA promoted an M1 to M2 transition in bone marrow-derived macrophages from both strains. Therefore, ATRA uncouples macrophage maturation and development of M1 phenotype and downmodulates macrophage-mediated immunity to L. major parasites. Cautions should be taken for the therapeutic use of ATRA, by considering direct effects on innate immunity to intracellular pathogens.
RESUMO
We investigated early cellular responses induced by infection with Leishmania major in macrophages from resistant C57/BL6 mice. Infection increased production of reactive oxygen species by resident, but not inflammatory peritoneal macrophages. In addition, infection increased activation of stress-activated protein kinases/c-Jun N-terminal kinases (SAPK/JNK) in resident, but not in inflammatory peritoneal macrophages. Infection also increased expression of membrane and soluble FasL, but infected macrophages remained viable after 48 h. Infection increased secretion of cytokines/chemokines TNF-α, IL-6, TIMP-1, IL-1RA, G-CSF, TREM, KC, MIP-1α, MIP-1ß, MCP-1, and MIP-2 in resident macrophages. Addition of antioxidants deferoxamine and N-acetylcysteine reduced ROS generation and JNK activation. Addition of antioxidants or JNK inhibitor SP600125 reduced secretion of KC. Furthermore, treatment with antioxidants or JNK inhibitor also reduced intracellular parasite replication. These results indicated that infection triggers a rapid cellular stress response in resident macrophages which induces proinflammatory signals, but is also involved in parasite survival and replication in host macrophages.
Assuntos
Leishmania major/fisiologia , Leishmaniose Cutânea/patologia , Leishmaniose Cutânea/parasitologia , Macrófagos/patologia , Macrófagos/parasitologia , Estresse Fisiológico , Animais , Antioxidantes/metabolismo , Morte Celular/efeitos dos fármacos , Quimiocinas/biossíntese , Proteína Ligante Fas/metabolismo , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Leishmania major/efeitos dos fármacos , Leishmania major/crescimento & desenvolvimento , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Macrófagos/efeitos dos fármacos , Macrófagos/enzimologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Parasitos/efeitos dos fármacos , Parasitos/crescimento & desenvolvimento , Parasitos/fisiologia , Inibidores de Proteínas Quinases/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Estresse Fisiológico/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacosRESUMO
We investigated how apoptosis pathways mediated by death receptors and caspase-8 affect cytokine responses and immunity to Leishmania major parasites. Splenic CD4 T cells undergo activation-induced apoptosis, and blockade of FasL-Fas interaction increased IFN-γ and IL-4 cytokine responses to L. major antigens. To block death receptor-induced death, we used mice expressing a T cell-restricted transgene for vFLIP. Inhibition of caspase-8 activation in vFLIP mice enhanced Th1 and Th2 cytokine responses to L. major infection, even in the Th1-prone B6 background. We also observed increased NO production by splenocytes from vFLIP mice upon T cell activation. Despite an exacerbated Th2 response, vFLIP mice controlled better L. major infection, with reduced lesions and lower parasite loads compared with WT mice. Moreover, injection of anti-IL-4 mAb in infected vFLIP mice disrupted control of parasite infection. Therefore, blockade of caspase-8 activity in T cells improves immunity to L. major infection by promoting increased Th1 and Th2 responses.
Assuntos
Caspase 8/metabolismo , Imunidade Celular/imunologia , Leishmania major/imunologia , Leishmaniose/imunologia , Leishmaniose/prevenção & controle , Células Th1/imunologia , Células Th2/imunologia , Animais , Antígenos de Protozoários/imunologia , Apoptose , Feminino , Humanos , Interleucina-4/metabolismo , Leishmaniose/parasitologia , Ativação Linfocitária/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas Virais/imunologiaRESUMO
Th1/Th2 cytokines play a key role in immune responses to Leishmania major by controlling macrophage activation for NO production and parasite killing. MDSCs, including myeloid precursors and immature monocytes, produce NO and suppress T cell responses in tumor immunity. We hypothesized that NO-producing MDSCs could help immunity to L. major infection. Gr1(hi)(Ly6C(hi)) CD11b(hi) MDSCs elicited by L. major infection suppressed polyclonal and antigen-specific T cell proliferation. Moreover, L. major-induced MDSCs killed intracellular parasites in a NO-dependent manner and reduced parasite burden in vivo. By contrast, treatment with ATRA, which induces MDSCs to differentiate into macrophages, increased development of lesions, parasite load, and T cell proliferation in draining LNs. Altogether, these results indicate that NO-producing MDSCs help protective immunity to L. major infection, despite suppressed T cell proliferation.
Assuntos
Imunidade Celular , Leishmania major/imunologia , Leishmaniose Cutânea/imunologia , Células Mieloides/imunologia , Células-Tronco/imunologia , Linfócitos T/imunologia , Animais , Células Cultivadas , Resistência à Doença/imunologia , Terapia de Imunossupressão , Leishmaniose Cutânea/parasitologia , Leishmaniose Cutânea/patologia , Masculino , Camundongos , Camundongos Endogâmicos , Monócitos/imunologia , Monócitos/metabolismo , Monócitos/parasitologia , Células Mieloides/metabolismo , Células Mieloides/parasitologia , Células-Tronco/parasitologia , Células-Tronco/patologia , Linfócitos T/metabolismo , Linfócitos T/parasitologiaRESUMO
Clearance of apoptotic exudate neutrophils (efferocytosis) induces either pro- or anti-inflammatory responses in mouse macrophages depending on host genetic background. In this study, we investigated whether neutrophil efferocytosis induces a stable macrophage phenotype that could be recalled by late restimulation with LPS. Bone marrow-derived macrophages previously stimulated by pro- but not anti-inflammatory neutrophil efferocytosis expressed a regulatory/M2b phenotype characterized by low IL-12 and high IL-10 production following restimulation, increased expression of LIGHT/TNF superfamily 14, Th2-biased T cell responses, and permissive replication of Leishmania major. Induction of regulatory/M2b macrophages required neutrophil elastase activity and was partially dependent on TLR4 signaling. These results suggested that macrophage differentiation to a regulatory phenotype plays a role in resolution of inflammation but could contribute to increased humoral Ab responses and parasite persistence in the infected host.
Assuntos
Interleucina-10/metabolismo , Interleucina-12/metabolismo , Macrófagos/imunologia , Neutrófilos/imunologia , Fagocitose/imunologia , Animais , Apoptose/imunologia , Células Cultivadas , Inflamação/imunologia , Interferon gama/imunologia , Interferon gama/farmacologia , Leishmania major/imunologia , Leishmaniose Cutânea/imunologia , Leishmaniose Cutânea/parasitologia , Elastase de Leucócito/metabolismo , Lipopolissacarídeos/imunologia , Lipopolissacarídeos/farmacologia , Macrófagos/metabolismo , Macrófagos/parasitologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos , Neutrófilos/citologia , Óxido Nítrico/metabolismo , Fagocitose/efeitos dos fármacos , Células Th2/imunologia , Células Th2/metabolismo , Receptor 4 Toll-Like/metabolismoRESUMO
Caspases are cysteine aspartases acting either as initiators (caspases 8, 9, and 10) or executioners (caspases 3, 6, and 7) to induce programmed cell death by apoptosis. Parasite infections by certain intracellular protozoans increase host cell life span by targeting caspase activation. Conversely, caspase activation, followed by apoptosis of lymphocytes and other cells, prevents effective immune responses to chronic parasite infection. Here we discuss how pharmacological inhibition of caspases might affect the immunity to protozoan infections, by either blocking or delaying apoptosis.
Assuntos
Antiprotozoários/uso terapêutico , Apoptose/efeitos dos fármacos , Inibidores de Caspase , Infecções por Protozoários/tratamento farmacológico , Animais , Antiprotozoários/imunologia , Apoptose/imunologia , Humanos , Tolerância Imunológica/efeitos dos fármacos , Camundongos , Infecções por Protozoários/enzimologia , Infecções por Protozoários/imunologia , Receptores de Morte Celular/imunologiaRESUMO
Neutrophils are involved in the initial steps of most responses to pathogens. In the present study, we evaluated the effects of the interaction of apoptotic vs. necrotic human neutrophils on macrophage infection by Leishmania amazonensis. Phagocytosis of apoptotic, but not viable, neutrophils by Leishmania-infected macrophages led to an increase in parasite burden via a mechanism dependent on TGF-beta1 and PGE2. Conversely, infected macrophages' uptake of necrotic neutrophils induced killing of L. amazonensis. Leishmanicidal activity was dependent on TNF-alpha and neutrophilic elastase. Nitric oxide was not involved in the killing of parasites, but the interaction of necrotic neutrophils with infected macrophages resulted in high superoxide production, a process reversed by catalase, an inhibitor of reactive oxygen intermediate production. Initial events after Leishmania infection involve interactions with neutrophils; we demonstrate that phagocytosis of these cells in an apoptotic or necrotic stage can influence the outcome of infection, driving either parasite survival or destruction.
Assuntos
Leishmaniose Cutânea/fisiopatologia , Macrófagos/parasitologia , Neutrófilos/imunologia , Neutrófilos/fisiologia , Animais , Apoptose , Catalase/farmacologia , Efeitos Psicossociais da Doença , Dinoprostona/fisiologia , Humanos , Leishmania mexicana/patogenicidade , Leishmania mexicana/fisiologia , Leishmaniose Cutânea/patologia , Necrose , Neutrófilos/patologia , Fagocitose , Superóxidos/metabolismo , Fator de Crescimento Transformador beta1/fisiologiaRESUMO
Following infection with Leishmania major, T cell activation and apoptosis can be detected in draining lymph nodes of C57BL/6-infected mice. We investigated the mechanisms involved in apoptosis and cytokine expression following T cell activation. After two weeks of infection, apoptotic T cells were not detected in draining lymph nodes but activation with anti-CD3 induced apoptosis in both CD4 and CD8 T cells. Treatment with anti-Fas Ligand, caspase-8 or caspase- 9 inhibitors did not block activation-induced T-cell death. We also investigated whether the blockade of caspase-8 activity would affect the expression of type-1 or type-2 cytokines. At early stages of infection, both CD4 and CD8 T cells expressed IFN-gamma upon activation. Treatment with the caspase-8 inhibitor zIETD-fmk (benzyl-oxycarbonyl-Ile- Glu(OMe)-Thr-Asp(OMe)-fluoromethyl ketone) reduced the proportion of CD8 T cells and IFN-gamma expression in both CD4 and CD8 T cells. We conclude that a non apoptotic role of caspase-8 activity may be required for T cell-mediated type-1 responses during L. major infection.
Assuntos
Apoptose/imunologia , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Inibidores de Caspase , Interferon gama/imunologia , Leishmania major/imunologia , Leishmaniose Cutânea/imunologia , Clorometilcetonas de Aminoácidos/farmacologia , Animais , Linfócitos T CD4-Positivos/enzimologia , Linfócitos T CD8-Positivos/enzimologia , Inibidores de Cisteína Proteinase/farmacologia , Feminino , Imunidade Celular , Leishmaniose Cutânea/parasitologia , Linfonodos/parasitologia , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Following infection with Leishmania major, T cell activation and apoptosis can be detected in draining lymph nodes of C57BL/6-infected mice. We investigated the mechanisms involved in apoptosis and cytokine expression following Tcellactivation. After two weeks of infection, apoptotic T cells were not detected in draining lymph nodes but activation with anti-CD3 induced apoptosis in both CD4 and CD8 T cells. Treatment with anti-FasLigand, caspase-8 or caspase- 9 inhibitors did not block activation-induced T-cell death. We also investigated whether the blockade of caspase-8 activity would affect the expression of type-1 or type-2 cytokines. At early stages of infection, both CD4 and CD8 T cells expressed IFN-gamma upon activation. Treatment with the caspase-8 inhibitor zIETD-fmk (benzyl-oxycarbonyl-Ile- Glu(OMe)-Thr-Asp(OMe)-fluoromethyl ketone) reduced the proportion of CD8 T cells and IFN-gamma expression in both CD4 and CD8T cells. We conclude that a non apoptotic role of caspase-8 activity may be required for T cell-mediated type-1 responses during L. major infection.
A ativação e a morte por apoptose de linfócitos T foram observadas em linfonodos drenantes de camundongos C57BL/6 infectados com Leishmania major. Investigamos os mecanismos envolvidos na apoptose e na expressão de citocinas após a ativação de linfócitos T. Após duas semanas de infecção, embora as células apoptóticas ainda não sejam detectadas em linfonodos drenantes, células T CD4 e CD8 sofrem apoptose após ativação com anti-CD3. O tratamento com anticorpo antagonista anti-Ligante de Fas, ou com inibidores das caspases-8 e 9, não bloqueou a morte induzida por ativação das células T. Investigamos também se a inibição da atividade da caspase-8 poderia afetar a expressão de citocinas tipo-1 ou tipo-2. Nos estágios iniciais da infecção, células T CD4 e CD8 de animais infectados com L. major expressaram IFN-gama após ativação. O tratamento com o inibidor de caspase-8 zIETD (benzoil-oxicarbonil-Ile-Glu(OMe)-Thr-Asp(OMe)-fluorometilcetona) durante a estimulação de células T reduziu a proporção de células T CD8 e a expressão de IFN-gama por células T CD4 e CD8. Concluimos que a atividade não apoptótica de caspase-8 pode ser necessária para o estabelecimento da imunidade mediada por células T durante a infecção por L. major.
Assuntos
Animais , Feminino , Camundongos , Apoptose/imunologia , /imunologia , /imunologia , /antagonistas & inibidores , Interferon gama/imunologia , Leishmania major/imunologia , Leishmaniose Cutânea/imunologia , Clorometilcetonas de Aminoácidos/farmacologia , /enzimologia , /enzimologia , Inibidores de Cisteína Proteinase/farmacologia , Imunidade Celular , Leishmaniose Cutânea/parasitologia , Linfonodos/parasitologiaRESUMO
We investigated the role of neutrophil elastase (NE) in interactions between murine inflammatory neutrophils and macrophages infected with the parasite Leishmania major. A blocker peptide specific for NE prevented the neutrophils from inducing microbicidal activity in macrophages. Inflammatory neutrophils from mutant pallid mice were defective in the spontaneous release of NE, failed to induce microbicidal activity in wild-type macrophages, and failed to reduce parasite loads upon transfer in vivo. Conversely, purified NE activated macrophages and induced microbicidal activity dependent on secretion of TNF-alpha. Induction of macrophage microbicidal activity by either neutrophils or purified NE required TLR4 expression by macrophages. Injection of purified NE shortly after infection in vivo reduced the burden of L. major in draining lymph nodes of TLR4-sufficient, but not TLR4-deficient mice. These results indicate that NE plays a previously unrecognized protective role in host responses to L. major infection.
Assuntos
Líquido Intracelular/imunologia , Líquido Intracelular/parasitologia , Leishmania major/imunologia , Elastase de Leucócito/fisiologia , Macrófagos/imunologia , Macrófagos/parasitologia , Neutrófilos/imunologia , Receptor 4 Toll-Like/metabolismo , Transferência Adotiva , Animais , Células Cultivadas , Técnicas de Cocultura , Ativação Enzimática/imunologia , Humanos , Líquido Intracelular/enzimologia , Leishmania major/crescimento & desenvolvimento , Elastase de Leucócito/metabolismo , Ativação de Macrófagos/imunologia , Macrófagos/enzimologia , Macrófagos/patologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , Neutrófilos/enzimologia , Neutrófilos/patologia , Neutrófilos/transplante , Transporte Proteico/imunologia , Receptor 4 Toll-Like/biossíntese , Receptor 4 Toll-Like/genéticaRESUMO
Parasitic diseases have worldwide medical and economical impact. Host T lymphocytes and the cytokines they produce determine the outcome of parasitic infections. Programmed cell death by apoptosis is induced in the course of parasitic infections, and affects cytokine production by removing activated effector T and B cells. In addition, engulfment of apoptotic cells promotes the secretion of cytokines that regulate intracellular replication of protozoan parasites. In this review, we discuss how the cross-talk between apoptosis and cytokines regulates parasitic infection.
Assuntos
Apoptose/imunologia , Linfócitos B/imunologia , Citocinas/imunologia , Infecções por Protozoários/imunologia , Linfócitos T/imunologia , Animais , HumanosRESUMO
In experimental Chagas' disease, lymphocytes from mice infected with Trypanosoma cruzi show increased apoptosis in vivo and in vitro. Treatment with a pan-caspase blocker peptide inhibited expression of the active form of effector caspase-3 in vitro and rescued both B and T cells from cell death. Injection of the caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethyl ketone, but not a control peptide, reduced parasitemia and lymphocyte apoptosis in T. cruzi-infected mice. Moreover, treatment with caspase inhibitor throughout acute infection increased the absolute numbers of B and T cells in the spleen and lymph nodes, without affecting cell infiltrates in the heart. Following treatment, we found increased accumulation of memory/activated CD4 and CD8 T cells, and secretion of IFN-gamma by splenocytes stimulated with T. cruzi antigens. Caspase inhibition in the course of infection reduced the intracellular load of parasites in peritoneal macrophages, and increased the production of TNF-alpha and nitric oxide upon activation in vitro. Our results indicate that inhibition of caspases with a pan-caspase blocker peptide improves protective type-1 immune responses to T. cruzi infection. We suggest that mechanisms of apoptosis are potential therapeutic targets in Chagas' disease.
Assuntos
Apoptose/imunologia , Inibidores de Caspase , Doença de Chagas/imunologia , Doença de Chagas/patologia , Linfócitos/enzimologia , Trypanosoma cruzi/imunologia , Clorometilcetonas de Aminoácidos/farmacologia , Animais , Apoptose/efeitos dos fármacos , Doença de Chagas/tratamento farmacológico , Doença de Chagas/enzimologia , Linfócitos/efeitos dos fármacos , Linfócitos/imunologia , Masculino , Camundongos , Camundongos Endogâmicos BALB CRESUMO
We investigated the role of the Fas ligand (FasL)/Fas death pathway on apoptosis and cytokine production by T cells in Trypanosoma cruzi infection. Anti-FasL, but not anti-TNF-alpha or anti-TRAIL, blocked activation-induced cell death of CD8 T cells and increased secretion of IL-10 and IL-4 by CD4 T cells from T. cruzi-infected mice. CD4 and CD8 T cells up-regulated Fas/FasL expression during T. cruzi infection. However, Fas expression increased earlier in CD8 T cells, and a higher proportion of CD8 T cells was activated and expressed IFN-gamma compared with CD4 T cells. Injection of anti-FasL in infected mice reduced parasitemia and CD8 T cell apoptosis and increased the ratio of CD8:CD4 T cells recovered from spleen and peritoneum. FasL blockade increased the number of activated T cells, enhanced NO production, and reduced parasite loads in peritoneal macrophages. Injection of anti-FasL increased IFN-gamma secretion by splenocytes responding to T. cruzi antigens but also exacerbated production of type 2 cytokines IL-10 and IL-4 at a late stage of acute infection. These results indicate that the FasL/Fas death pathway regulates apoptosis and coordinated cytokine responses by type 1 CD8 and type 2 CD4 T cells in T. cruzi infection.
Assuntos
Linfócitos T CD4-Positivos/metabolismo , Linfócitos T CD8-Positivos/metabolismo , Doença de Chagas/imunologia , Transdução de Sinais , Receptor fas/metabolismo , Animais , Apoptose , Linfócitos T CD4-Positivos/fisiologia , Linfócitos T CD8-Positivos/fisiologia , Proliferação de Células , Doença de Chagas/metabolismo , Citocinas/metabolismo , Proteína Ligante Fas/metabolismo , Imunidade Celular , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Modelos Imunológicos , Regulação para CimaRESUMO
Apoptosis mediated by Fas ligand (FasL) initiates inflammation characterized by neutrophilic infiltration. Neutrophils undergo apoptosis and are ingested by macrophages. Clearance of dead neutrophils leads to prostaglandin- and transforming growth factor-beta-dependent replication of Leishmania major in macrophages from susceptible mice. How L. major induces neutrophil turnover in a physiological setting is unknown. We show that BALB/c FasL-sufficient mice are more susceptible to L. major infection than are FasL-deficient mice. FasL promotes the apoptosis of infected resident macrophages and attracts neutrophils. Furthermore, FasL-sufficient neutrophils exacerbate L. major replication in macrophages, whereas FasL-deficient neutrophils induce parasite killing. These contrasting effects are due to delaying apoptosis and the clearance of FasL-deficient neutrophils. The transfer of neutrophils exacerbates infection in FasL-sufficient mice but reduces infection in FasL-deficient mice. Depletion of neutrophils abolishes the susceptibility of FasL-sufficient mice. These data illustrate a deleterious role of the FasL-mediated turnover of neutrophils on L. major infection.
Assuntos
Leishmania major/crescimento & desenvolvimento , Leishmania major/imunologia , Leishmaniose Cutânea/imunologia , Glicoproteínas de Membrana/imunologia , Neutrófilos/imunologia , Neutrófilos/patologia , Animais , Apoptose , Morte Celular/imunologia , Modelos Animais de Doenças , Suscetibilidade a Doenças , Proteína Ligante Fas , Leishmaniose Cutânea/genética , Leishmaniose Cutânea/patologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos KnockoutRESUMO
During Trypanosoma cruzi infection, T cells up-regulate caspase-8 activity. To assess the role of caspase-8 in T cell-mediated immunity, we investigated the effects of caspase-8 inhibition on T cells in viral FLIP (v-FLIP) transgenic mice. Compared with wild-type controls, increased parasitemia was observed in v-FLIP mice infected with T. cruzi. There was a profound decrease in expansion of both CD4 and CD8 T cell subsets in the spleens of infected v-FLIP mice. We did not find differences in activation ratios of T cells from transgenic or wild-type infected mice. However, the numbers of memory/activated CD4 and CD8 T cells were markedly reduced in v-FLIP mice, possibly due to defective survival. We also found decreased production of IL-2 and increased secretion of type 2 cytokines, IL-4 and IL-10, which could enhance susceptibility to infection. Similar, but less pronounced, alterations were observed in mice treated with the caspase-8 inhibitor, zIETD. Furthermore, blockade of caspase-8 by zIETD in vitro mimicked the effects observed on T. cruzi infection in vivo, affecting the generation of activated/memory T cells and T cell cytokine production. Caspase-8 is also required for NF-kappaB signaling upon T cell activation. Blockade of caspase-8 by either v-FLIP expression or treatment with zIETD peptide decreased NF-kappaB responses to TCR:CD3 engagement in T cell cultures. These results suggest a critical role for caspase-8 in the establishment of T cell memory, cell signaling, and regulation of cytokine responses during protozoan infection.
Assuntos
Caspases/fisiologia , Doença de Chagas/imunologia , Citocinas/biossíntese , Células Th2/enzimologia , Células Th2/imunologia , Trypanosoma cruzi/imunologia , Animais , Caspase 8 , Inibidores de Caspase , Caspases/biossíntese , Diferenciação Celular/genética , Diferenciação Celular/imunologia , Células Cultivadas , Doença de Chagas/enzimologia , Doença de Chagas/genética , Citocinas/metabolismo , Predisposição Genética para Doença , Imunidade Celular/genética , Imunidade Inata/genética , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Oligopeptídeos/farmacologia , Células Th2/citologia , Células Th2/metabolismo , Regulação para Cima/genética , Regulação para Cima/imunologia , Proteínas Virais/genéticaRESUMO
Macrophages are host cells for the pathogenic parasite Leishmania major. Neutrophils die and are ingested by macrophages in the tissues. We investigated the role of macrophage interactions with inflammatory neutrophils in control of L. major infection. Coculture of dead exudate neutrophils exacerbated parasite growth in infected macrophages from susceptible BALB, but killed intracellular L. major in resistant B6 mice. Coinjection of dead neutrophils amplified L. major replication in vivo in BALB, but prevented parasite growth in B6 mice. Neutrophil depletion reduced parasite load in infected BALB, but exacerbated infection in B6 mice. Exacerbated growth of L. major required PGE(2) and TGF-beta production by macrophages, while parasite killing depended on neutrophil elastase and TNF-alpha production. These results indicate that macrophage interactions with dead neutrophils play a previously unrecognized role in host responses to L. major infection.