RESUMO
Here, we analysed the use of Vbeta-TCR regions by CD4+ and CD8+ T cells from acute and chronic chagasic patients using flow cytometry. We determined the Vbeta expression in cells freshly isolated from patients, as well as after in vitro stimulation with antigens derived from epimastigote (EPI) or trypomastigote (TRYPO) forms of Trypanosoma cruzi. Analysis of Vbeta-TCR expression of T cells freshly isolated from patients showed a decrease in Vbeta5 expression in the CD4+ T-cell population from acutely infected individuals, whereas CD4+Vbeta5+ T cells were found to be increased in chronic patients with the cardiac, but not indeterminate, clinical form. After culturing peripheral blood mononuclear cells (PBMC) from chronic patients with EPI or TRYPO, we found that both antigenic preparations led to a preferential expansion of CD4+Vbeta5+ T cells. EPI stimulation also led to the expansion of CD8+Vbeta5+ T cells, whereas TRYPO led to the expansion of this cell population only if PBMC were from cardiac and not indeterminate patients. We observed that TRYPO stimulation led to an increase in the frequency of CD4+Vbeta17+ T cells in cultures of PBMC from indeterminate patients, whereas an increase in the frequency of CD8+Vbeta17+ T cells was found upon TRYPO stimulation of PBMC from cardiac patients. Despite this increase in the frequency of Vbeta17+ T-cell populations upon TRYPO stimulation, the same antigenic preparation led to a much higher expansion of Vbeta5+ T cells. These results show a differential expression of Vbeta5-TCR in cells freshly isolated from chagasic patients in different stages of the disease and that parasite-specific antigens stimulate a portion of the T-cell repertoire with preferential usage of Vbeta5-TCR.
Assuntos
Doença de Chagas/imunologia , Receptores de Antígenos de Linfócitos T alfa-beta/imunologia , Linfócitos T/imunologia , Doença Aguda , Animais , Antígenos de Protozoários/imunologia , Contagem de Linfócito CD4 , Linfócitos T CD4-Positivos/imunologia , Doença Crônica , Cardiopatias/imunologia , Humanos , Trypanosoma cruzi/imunologiaRESUMO
Cellular and humoral immune responses to Schistosoma mansoni antigen preparations were evaluated in individuals presumed to be susceptible or resistant to reinfection after chemotherapeutic cure. A consistent proliferative increase in the response to soluble egg antigen (SEA) was observed post-treatment in both the susceptible and resistant groups. However, this change was not related to resistance. Isotype studies showed that IgM antibody levels to soluble worm antigen preparation (SWAP) and cercariae antigens were significantly higher in the resistant group than in the susceptible group. Post-treatment, an increase in IgE anti-SWAP and anti-schistosomular tegument (STEG) responses and a decrease in IgG4 anti-SEA and anti-STEG responses were observed in the resistant group. These finding are similar to those we have reported previously for a putative resistant group termed endemic normals, and are compatible with immunologic studies in different endemic areas. Together, these findings indicate that even on the population level, high IgE specificities coupled with low IgG4 specificities correlate well with documented resistance to reinfection.
Assuntos
Schistosoma mansoni/imunologia , Esquistossomose mansoni/imunologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Anticorpos Anti-Helmínticos/sangue , Antígenos de Helmintos/imunologia , Antimaláricos/uso terapêutico , Brasil/epidemiologia , Criança , Pré-Escolar , Suscetibilidade a Doenças/imunologia , Feminino , Humanos , Imunidade Celular , Isotipos de Imunoglobulinas/sangue , Masculino , Camundongos , Pessoa de Meia-Idade , Oxamniquine/uso terapêutico , Prevalência , Recidiva , Esquistossomose mansoni/tratamento farmacológico , Esquistossomose mansoni/epidemiologiaRESUMO
It has previously been demonstrated that Trypanosoma cruzi-derived antigens (TRP) and human parasite-specific antibodies (Id) stimulate proliferation of cells from Chagasic patients. More recently, we have shown that activated T cells and CD5+ B cells are present in elevated levels in the peripheral blood of Chagasic patients. Upon in vitro exposure to these two different types of stimulatory molecules (TRP, Id), we now show that each of these elevated populations respond differentially to TRP or Id. We found that stimulation with TRP led to preferential expansion of activated T cells, while Id preferentially stimulated CD5+ B cells and CD8+ T cells. Moreover, this expansion of CD5+ B cells by Id was even more pronounced in cultures of cells from Chagasic patients with the severe, cardiac form of the disease, as compared to indeterminate patients. CD8+ T cells comprise approximately 50% of the total T cells in cultures stimulated by Id while in TRP-stimulated cultures their frequency is proportionally lower. Since parasite antigens and antiparasite antibodies are always present in the host during the chronic phase of the disease, they may also be involved with differential activation mechanisms of these cell populations in vivo.
Assuntos
Subpopulações de Linfócitos B/imunologia , Antígenos CD5/metabolismo , Doença de Chagas/imunologia , Linfócitos T/imunologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Anticorpos Antiprotozoários/administração & dosagem , Antígenos de Protozoários/administração & dosagem , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Humanos , Técnicas In Vitro , Interferon gama/biossíntese , Interleucina-10/biossíntese , Ativação Linfocitária , Pessoa de Meia-Idade , Trypanosoma cruzi/imunologiaRESUMO
The opportunities and challenges for the study and control of parasitic diseases in the 21st century are both exciting and daunting. Based on the contributions from this field over the last part of the 20th century, we should expect new biologic concepts will continue to come from this discipline to enrich the general area of biomedical research. The general nature of such a broad category of infections is difficult to distill, but they often depend on well-orchestrated, complex life cycles and they often involve chronic, relatively well-balanced host/parasite relationships. Such characteristics force biological systems to their limits, and this may be why studies of these diseases have made fundamental contributions to molecular biology, cell biology and immunology. However, if these findings are to continue apace, parasitologists must capitalize on the new findings being generated though genomics, bioinformatics, proteomics, and genetic manipulations of both host and parasite. Furthermore, they must do so based on sound biological insights and the use of hypothesis-driven studies of these complex systems. A major challenge over the next century will be to capitalize on these new findings and translate them into successful, sustainable strategies for control, elimination and eradication of the parasitic diseases that pose major public health threats to the physical and cognitive development and health of so many people worldwide.
Assuntos
Alergia e Imunologia/tendências , Biologia Molecular/tendências , Doenças Parasitárias/prevenção & controle , Pesquisa/tendências , Tomada de Decisões , Previsões , Humanos , Prática de Saúde PúblicaRESUMO
Exposure of neonatal mice to appropriate, cross-reactive Id (CRI) preparations alters immune responsiveness, ameliorates pathology, and prolongs survival of animals upon subsequent Schistosoma mansoni infection. However, because schistosome infections profoundly affect host immunobiology, which responses are effected by neonatal Id exposure alone and which responses are influenced by infection is unclear. To directly examine the schistosome soluble egg Ag (SEA)-specific immune responses altered by CRI exposure, neonatal mice were injected with CRI-expressing (CRI+) SEA-specific Ab preparations, SEA-specific Abs that did not express CRI (CRI-), or normal mouse Ig. At 9 wk of age, only mice that were neonatally exposed to CRI+ anti-SEA Abs displayed significant SEA-specific IgG serum levels and spleen cell proliferative responses. SEA-stimulated spleen cells from these CRI+-exposed mice also produced IFN-gamma, although not at significantly higher levels than mice receiving CRI- Id or normal mouse Ig. If CRI+-exposed mice were also injected with SEA at 8 wk of age, the 9-wk IFN-gamma responses were significantly higher than those of the other neonatal injection groups. The presence of both CRI and anti-CRI in the sera of animals neonatally injected with CRI, but receiving no exposure to S. mansoni Ags or infection, suggested a functional idiotypic network led to these responses. These data demonstrate that appropriate idiotypic exposure induces B and T cell responsiveness to the Ag recognized by the Id and support the hypothesis that neonatal idiotypic exposure can be an important immunoregulatory factor in schistosomiasis.
Assuntos
Animais Recém-Nascidos/imunologia , Anticorpos Anti-Helmínticos/biossíntese , Antígenos de Helmintos/imunologia , Complexo CD3 , Imunização Passiva , Idiótipos de Imunoglobulinas/imunologia , Óvulo/imunologia , Schistosoma mansoni/imunologia , Animais , Anticorpos Anti-Idiotípicos/sangue , Antígenos de Helmintos/farmacologia , Reações Cruzadas , Feminino , Soros Imunes/farmacologia , Imunidade Celular , Imunização Passiva/métodos , Idiótipos de Imunoglobulinas/administração & dosagem , Injeções Intraperitoneais , Camundongos , Camundongos Endogâmicos CBA , Coelhos , Receptores de Antígenos de Linfócitos T/imunologia , Baço/citologia , Baço/imunologiaRESUMO
The current study has compared the activation status and the expression of the CD28 molecule on circulating CD4+ and CD8+ lymphocytes from patients with different clinical forms of schistosomiasis. The data show that patients with acute schistosomiasis have an increase on the mean percentage of CD4+ HLA-DR+ cells, whereas chronic asymptomatic patients exhibit an increased mean percentage of CD8+ HLA-DR+ cells. Patients with the hepatosplenic disease showed an increase in both CD4+ HLA-DR+ and CD8+ HLA-DR+ cells. Despite the high levels of CD8+ HLA-DR+ cells in hepatosplenic patients, they presented a decreased ratio of CD8+ CD28+/CD8+ cells. These findings of a different percentage of circulating CD8+ CD28+ cells might explain the different in vitro cellular reactivity of asymptomatic and hepatosplenic patients and the defects in the cytokine secretion patterns reported in individuals with hepatosplenic schistosomiasis.
Assuntos
Antígenos CD28/imunologia , Ativação Linfocitária , Esquistossomose mansoni/imunologia , Subpopulações de Linfócitos T/imunologia , Doença Aguda , Adolescente , Adulto , Idoso , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Estudos de Casos e Controles , Criança , Doença Crônica , Citometria de Fluxo , Antígenos HLA-DR/imunologia , Humanos , Hepatopatias Parasitárias/imunologia , Pessoa de Meia-Idade , Esplenopatias/imunologia , Esplenopatias/parasitologiaRESUMO
Complementary DNA, encoding the mitochondrial enzyme NADH-ubiquinone oxidoreductase subunit 5 (SmND5) of the human parasite Schistosoma mansoni was isolated by screening a S. mansoni cDNA library with a human androgen receptor (hAR) cDNA probe. The complete nucleotide and deduced aminoacid sequences of SmND5 were determined. Southern blot analysis revealed the occurrence of a single copy gene for SmND5 and by means of RT-PCR, it was shown that sex- and stage-specific expression of SmND5 occurred. In order to establish a functional relationship between the mitochondrial enzyme and the androgen receptor, the effects of testosterone were compared to those of classical respiratory chain inhibitors, using adult schistosome and beef heart submitochondrial particles. Physiological concentrations of testosterone were able to inhibit the maintenance of proton gradient across the mitochondrial membranes, as well as ATP synthesis. The steroid was found to be cytotoxic to the larvae, but not to adult schistosomes. A model is proposed to explain the observed in vivo testosterone-related differences in worm burdens, in experimental chronic infections.
Assuntos
Mitocôndrias Cardíacas/metabolismo , NADH NADPH Oxirredutases/química , NADH NADPH Oxirredutases/genética , Schistosoma mansoni/enzimologia , Sequência de Aminoácidos , Animais , Sequência de Bases , Abelhas/enzimologia , Caenorhabditis elegans/enzimologia , Bovinos , Clonagem Molecular , Sequência Consenso , DNA Complementar , Complexo I de Transporte de Elétrons , Biblioteca Gênica , Humanos , Mitocôndrias Cardíacas/efeitos dos fármacos , Dados de Sequência Molecular , NADH NADPH Oxirredutases/metabolismo , Consumo de Oxigênio/efeitos dos fármacos , Receptores Androgênicos/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Schistosoma mansoni/genética , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Partículas Submitocôndricas/efeitos dos fármacos , Partículas Submitocôndricas/metabolismo , Testosterona/farmacologiaRESUMO
People infected with Trypanosoma cruzi remain so for life, yet only 30-40% of these individuals develop characteristic chagasic cardiomyopathies. Similarly, when infected with the Brazilian strain of T. cruzi, DBA/2 mice develop severe cardiac damage while B10.D2 mice do not. To better understand the immunological parameters that may be involved in the disease process, we have used this murine model (DBA/2 vs B10.D2) and compared the changes in cytokine production during the course of infection with T cruzi. Concanavalin A (Con A) stimulation of spleen cells harvested during the acute phase (day 30) resulted in similarly high levels of IFN-gamma in both mouse strains. However, the amount of IFN-gamma in supernatants from cultures of B10.D2 spleen cells initiated during the chronic phase (day 72) was at subacute levels, whereas secretion by chronic DBA/2 spleen cells remained high. In addition, Con A-stimulated spleen cells from acute DBA/2 mice produced approximately twice as much IL-10 and significantly more IL-4 than cells from B10.D2 mice. IL-4 secretion remained low by cells from chronic B10.D2 mice, but when using cells from chronic DBA/2 mice, levels continued to increase beyond the already high levels secreted by cells harvested during the acute phase. Proliferative responses to Con A stimulation by spleen cells from DBA/2 mice were significantly higher than those from B10.D2 mice in both the acute and chronic phases. These data suggest that enhanced responses in DBA/2 mice, which may be related to a higher parasite burden, a lack of down-regulation, and/or the onset of autoimmune phenomena, correlate with the more severe cardiomyopathy seen in pathopermissive mice.
Assuntos
Doença de Chagas/imunologia , Citocinas/fisiologia , Modelos Animais de Doenças , Animais , Interferon gama , Interleucina-10 , Interleucina-4 , Camundongos , Camundongos Endogâmicos DBAAssuntos
Oxamniquine/farmacologia , Schistosoma mansoni/efeitos dos fármacos , Esquistossomose mansoni/tratamento farmacológico , Adolescente , Adulto , Animais , Antiparasitários/farmacologia , Brasil , Criança , Pré-Escolar , Protocolos Clínicos , Estudos Transversais , Seguimentos , Humanos , Imunidade Inata , Pessoa de Meia-Idade , Schistosoma mansoni/patogenicidadeRESUMO
People infected with Trypanosoma cruzi remain so for life, yet only 30-40 percent of these individuals develop characteristic chagasic cardiomyopathies. Similarly, when infected with the Brazilian strain of T. cruzi, DBA/2 mice develop severe cardiac damage while B10.D2 mice do not. To better understand the immunological parameters that may be involved in the disease process, we have used this murine model (DBA/2 vs B10.D2) and compared to changes in cytokine production during the course of infection with T. cruzi. Concanavalin A (Con A) stimulation of spleen cells harvested during the acute phase (day 30) resulted in similarly high levels of IFN-gamma in both mouse strains. However, the amount of IFN-gamma in supernatants from cultures of B10.D2 spleen cells initiated during the chronic phase (day 72) was at subacute levels, whereas secretion by chronic DBA/2 spleen cells remained high. In addition, Con A-stimulated spleen cells from acute DBA/2 mice produced approximately twice as much IL-10 and significantly more IL-4 than cells from B10.D2 mice. IL-4 secretion remained low by cells from chronic B10.D2 mice, but when using cells from chronic DBA/2 mice, levels continued to increase beyond the already high levels secreted by cells harvested during the acute phase. Proliferative responses to Con A stimulation by spleen cells from DBA/2 mice were significantly higher than those from B10.D2 mice in both the acute and chronic phases. These data suggest that enhanced responses in DBA/2 mice, which may be related to a higher parasite burden, a lack of down-regulation, and/or the onset of autoimmune phenomena, correlate with the more severe cardiomyopathy seen in pathopermissive mice.