RESUMO
Chagas disease induced by Trypanosoma cruzi (Tc) infection is an important cause of mortality and morbidity affecting the cardiovascular system for which presently available therapies are insufficient and largely inadequate. Intravenous immunoglobulin (IVIg) is a therapeutic preparation containing normal polyspecific IgG obtained from plasma pools of several thousand healthy donors and is used in several autoimmune, inflammatory and infectious diseases. In the study of heart from mice chronically infected with Tc, we observed that IVIg restores type 1 atrioventricular block or bradycardia. In the present study, we investigated the effects of IVIg in acute Tc infection. Intravenous immunoglobulin administration after the first week of infection was associated with an increase in survival time. Taken together, results observed in the chronic and in the acute phase associate IVIg treatment with a favourable outcome in T. cruzi infection.
Assuntos
Doença de Chagas/terapia , Imunoglobulinas Intravenosas/uso terapêutico , Animais , Modelos Animais de Doenças , Feminino , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Análise de Sobrevida , Fatores de TempoRESUMO
Trypanosoma cruzi proteinases are involved in host cell invasion in human patients and in mouse models. In mice, murine alpha(2)-macroglobulin (MAM) and murinoglobulin are circulating plasma proteinase inhibitors that also have important roles in inflammation and immune modulation. To define their role in experimental Chagas disease, we investigated the susceptibility to T. cruzi infection of mice that are deficient only in alpha2-macroglobulins (AM-KO) or in both MAM and monomeric murinoglobulin-1 (MM-KO), relative to the wild type (WT). Despite the high parasite load, parasitemia was lower in AM-KO and MM-KO mice than in WT mice. Nevertheless, we observed a significantly higher parasite load in the hearts of AM-KO and MM-KO mice, i.e., more amastigote nests and inflammatory infiltrates than in WT mice. This result demonstrates a protective role for MAM in the acute phase of murine T. cruzi infection. We further demonstrated in vitro that human alpha2-macroglobulins altered the trypomastigote morphology and motility in a dose-dependent way, and that also impaired T. cruzi invasion in cardiomyocytes. Finally, we demonstrated that the levels of transforming growth factor beta in AM-KO mice increased significantly in the third week postinfection, concomitant with high amastigote burden and important fibrosis. Combined, these in vivo and in vitro findings demonstrate that the MAM contribute to the resistance of mice to acute myocarditis induced by experimental T. cruzi infection.
Assuntos
Cardiomiopatia Chagásica/etiologia , Doença de Chagas/etiologia , Miocárdio/patologia , Fator de Crescimento Transformador beta/sangue , Trypanosoma cruzi/patogenicidade , alfa-Macroglobulinas/deficiência , Animais , Cardiomiopatia Chagásica/imunologia , Cardiomiopatia Chagásica/parasitologia , Cardiomiopatia Chagásica/patologia , Doença de Chagas/imunologia , Doença de Chagas/parasitologia , Doença de Chagas/patologia , Endopeptidases/fisiologia , Feminino , Fibrose , Humanos , Técnicas In Vitro , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Inibidores de Proteases/sangue , Soroglobulinas/deficiência , Soroglobulinas/genética , Trypanosoma cruzi/efeitos dos fármacos , Trypanosoma cruzi/enzimologia , alfa-Macroglobulinas/genética , alfa-Macroglobulinas/farmacologiaRESUMO
We have previously observed that aged lupus-prone (NZB/NZW)Fl (BWF1) mice when infected with Plasmodium chabaudi show an improvement in their clinical lupus-like symptoms. In order to study the mechanisms involved in the long-lasting protective effect of the P. chabaudi infection in lupus-prone mice we analysed specific aspects of the cellular response, namely the profiles of cytokine mRNA expression and cytokine secretion levels in old BWF1 mice, in comparison with uninfected age-matched BWF1 mice and infected or uninfected BALB/c mice. Two months after infection, cells from BWF1 mice were stimulated with concanavalin A (Con A) and demonstrated a recovery of T cell responsiveness that reached the levels obtained with BALB/c cells. Old BWF1 mice showed high levels of interferon-gamma (IFN-gamma) and IL-5 production and correspondingly low levels of IL-2 and IL-4 secretion before infection with P. chabaudi. Infection did not modify the IFN-gamma levels of BWF1 T cells, whereas it considerably increased the secretion of the Th2-related cytokines IL-4, IL-5 and IL-10. In addition, only BWF1 T cells showed increased mRNA expression of tumour necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta (TGF-beta). This counter-regulatory cytokine network of infected BWF1 mice may be involved in the improvement of their lupus symptoms. The results of our investigations using the complex model of P. chabaudi infection can be extended and, by using more restricted approaches, it may be possible to explain the multiple regulatory defects of lupus-prone mice.
Assuntos
Citocinas/biossíntese , Citocinas/imunologia , Lúpus Eritematoso Sistêmico/genética , Lúpus Eritematoso Sistêmico/imunologia , Malária/imunologia , Plasmodium chabaudi/imunologia , Animais , Concanavalina A/farmacologia , Cruzamentos Genéticos , Citocinas/metabolismo , Feminino , Predisposição Genética para Doença , Imunoglobulinas/sangue , Ativação Linfocitária/genética , Linfocinas/biossíntese , Linfocinas/genética , Malária/sangue , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos NZB , RNA Mensageiro/biossíntese , Linfócitos T/imunologia , Linfócitos T/metabolismoRESUMO
A 72 kDa Trypanosoma cruzi glycoprotein recognized by the 164C11 monoclonal antibody (IgM isotype) was purified by preparative electrophoresis. The antigenic preparation obtained, named TcY 72, was used to immunize C57Bl/10 mice. The following results were observed after immunization: (1) induction of higher titres of IgG than IgM antibodies, as evaluated by indirect immunofluorescence; (2) significant DTH after injection of epimastigotes in mice footpads; (3) peak parasitemia in immunized mice was significantly reduced and animals were negative by 13 days post-infection, although the mice still succumb to infection; (4) the phenotypic analysis of spleen cell populations showed a decrease in the CD4/CD8 ratio in immunized mice. Taken as a whole, these findings indicate that TcY 72 is immunogenic and potentially important for protective immunity.
Assuntos
Antígenos de Protozoários/imunologia , Doença de Chagas/imunologia , Glicoproteínas , Imunização , Trypanosoma cruzi/imunologia , Animais , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Fatores de TempoRESUMO
Several studies in mice have strengthened the active role played either by CD4+, CD8+ or both T cell subsets in conferring resistance to Trypanosoma cruzi infection. To date, no studies reported the role played by T cell subsets on parasite multiplication in different organs. In the present work, mice were infected with CL strain of T. cruzi and T cell subset activities were blocked by i.p. injection of monoclonal antibody (mAb) directed against CD4, or IAk, or CD8 molecules. The effect of these treatments was determined by counting the number of parasite nests in heart and liver sections 16 days after infection. Our results showed that mice treated with anti-CD4 or anti-IAk mAbs presented a significant increase in the parasite load in the hearts and in the livers. Conversely, the number of parasites in hearts of anti-CD8 treated mice did not increase significantly. This treatment, however, resulted in a 20-fold increase in the number of parasites found in the liver. Simultaneous depletion of both T cell subsets by treatment of mice with anti-CD4/CD8 mAbs had, in the heart, the same effect as the CD4 depletion. Interestingly, this treatment caused a dramatic increase (200-fold) in the T. cruzi parasitism of the liver. These results indicate that the activity of T cell subsets against T. cruzi varies according to the infected organ.
Assuntos
Doença de Chagas/imunologia , Fígado/parasitologia , Subpopulações de Linfócitos T/imunologia , Trypanosoma cruzi/imunologia , Animais , Anticorpos Monoclonais/imunologia , Anticorpos Antiprotozoários/imunologia , Feminino , Coração/parasitologia , Imunidade Celular , Depleção Linfocítica , Camundongos , Camundongos Endogâmicos C3HRESUMO
In this work, the authors analysed T and B lymphocyte subsets and cytokine production in the spleen of BALB/c mice during polyclonal lymphocyte activation (primary infection) and parasite-specific response to Plasmodium chabaudi chabaudi (secondary infection). The secondary response was evaluated in fully immunoprotected animals, 60 days after a chloroquine-cured infection. The authors observed that in polyclonal lymphocyte activation antibody-secreting cells of all isotypes increased, with predominance of IgG2a and IgG3 classes. At that time, IFN-gamma was largely produced, but IL-4/IL-5 were just slightly enhanced. In mice re-infected after 60 days, the Ig-isotype pattern was restricted to IgG1 and only IL-4/IL-5 were produced. In both responses, however, the levels of IL-2 were greatly reduced, while those of IL-10 were enhanced to similar levels. The different involvement of Th1 and Th2 cells in both responses was confirmed through analysis of CD45RB expression by CD4+ cells. The authors observed that CD45RBhigh cells were the major CD4+ subpopulation in primary infected mice, while CD45RBlow cells predominated in 60 days re-infected animals. Moreover, the great majority of activated (large) CD4+ cells in the primary infection belonged to the CD45RBhigh subset, while after reinfection most of the CD4+ large had a CD45RBlow phenotype.
Assuntos
Anticorpos Antiprotozoários/biossíntese , Linfócitos B/imunologia , Linfócitos T CD4-Positivos/imunologia , Isotipos de Imunoglobulinas/biossíntese , Memória Imunológica , Interferon gama/biossíntese , Interleucina-4/biossíntese , Antígenos Comuns de Leucócito/metabolismo , Plasmodium chabaudi/imunologia , Animais , Células Produtoras de Anticorpos/metabolismo , Linfócitos B/metabolismo , Linfócitos T CD4-Positivos/metabolismo , Linfócitos T CD8-Positivos/imunologia , Feminino , Cinética , Malária/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Especificidade da EspécieRESUMO
1. In schistosomal infection, the hyperergic acute phase of the disease evolves progressively into the chronic one, with establishment of a relative equilibrium between the parasites and the corresponding host responses. This down-regulation of host reactivity is considered to be under the control of T-lymphocyte circuits. 2. In the present study, we investigated lymphocyte populations in spleens of normal mice and the kinetics of the B-cell number increase in mice in the acute, chronic and late chronic phases of schistosomal infection, and we monitored their proliferation and activity in antibody isotype secretion. 3. We observed polyclonal B-cell activation and modulation of Ig isotype production, compatible with the alternate predominance of TH2 and TH1 lymphocyte subsets, in the acute and the chronic phases of the disease, respectively.
Assuntos
Linfócitos B/imunologia , Esquistossomose mansoni/imunologia , Linfócitos T/imunologia , Animais , Linfócitos B/metabolismo , Citocinas/biossíntese , Feminino , Citometria de Fluxo , Granuloma/imunologia , Isotipos de Imunoglobulinas/biossíntese , Isotipos de Imunoglobulinas/imunologia , Ativação Linfocitária , Contagem de Linfócitos , Masculino , Camundongos , Camundongos Endogâmicos C3H , Baço/imunologia , Linfócitos T/metabolismo , Fatores de TempoRESUMO
1. In schistosomal infection, the hyperergic acute phase of the disease evolves progressively into the chronic one, with establishment of a relative equilibrium between the parasites and the corresponding host responses. This down-regulation of host reactivity is considered to be under the control of T-lymphocyte circuits. 2. In the present study, we investigated lymphocyte populations in spleens of normal mice and the kinetics of the B-cell number increase in mice in the acute, chronic and late chronic phases of schistosomal infection, and we monitored their proliferation and activity in antibody isotype secretion. 3. We observed polyclonal B-cell activation and modulation of Ig isotype production, compatible with the alternate predominance of TH2 and TH1 lymphocyte subsets, in the acute and the chronic phases of the disease, respectively.
Assuntos
Animais , Feminino , Masculino , Camundongos , Linfócitos B , Esquistossomose mansoni , Linfócitos T , Linfócitos B , Baço/imunologia , Citocinas , Citometria de Fluxo , Granuloma , Isotipos de Imunoglobulinas , Contagem de Linfócitos , Linfócitos T , Fatores de Tempo , Ativação LinfocitáriaRESUMO
This paper discusses current evidence for the relationship between polyclonal lymphocyte activation, specific immunosuppression with decreased resistance, and autoimmune pathology, that are all often found associated with infections by a variety of virus, bacteria and parasites. The central question of class determination of immune effector activities is considered in the context of the cellular targets for nonspecific mitogenic activities associated with infection. A model is presented to integrate these findings: mitogens produced by the microorganism or the infected cells are preferentially active on CD5 B cells; the resulting over-production of IL-10 will tend to bias all immune activities into a Th2-mode of effector functions, with high titers of polyclonal antibodies and little or no production of gamma IFN and other "inflammatory" lymphokines that often mediate resistance. In turn, these conditions allow for parasite persistence and the corresponding long-term disregulation of self-directed immune reactivities, resulting in autoimmunity in the chronic phase. This model would predict that selective immunization with the mitogenic principles involved in deregulation, could stand better chances than strategies of vaccination based on immunopotentiation against other, functionally neutral antigenic epitopes. It is argued, however, that the complexity of immune responses and their regulation, together with our ignorance on the genetic controls of class-determination, offer poor prospects for a scientifically-based, rational development of vaccines in the near future. It is suggested that empirically-based and technologically developed vaccines might succeed, while basic scientific approaches are reinforced and given the time to provide a better understanding of those processes.
Assuntos
Região Variável de Imunoglobulina/imunologia , Síndromes de Imunodeficiência/etiologia , Infecções/imunologia , Animais , Doenças Autoimunes/etiologia , Doenças Autoimunes/imunologia , Humanos , Tolerância Imunológica , Síndromes de Imunodeficiência/genética , Síndromes de Imunodeficiência/imunologia , Infecções/complicações , Inflamação/imunologia , Ativação Linfocitária , Subpopulações de Linfócitos/imunologia , Camundongos , Camundongos Mutantes/imunologia , Modelos Biológicos , VacinasRESUMO
Early wasting and subsequent mortality may occur in mice of some inbred strains following infection with Trypanosoma cruzi. It was hypothesized that TNF alpha/cachectin might be involved in this process. Thus, sera collected from mice of strains differing in their susceptibility or resistance to Trypanosoma cruzi infection were checked for the presence and level of TNF alpha, a cytokine able to exert acute toxic effects. C3H/HeJ or C3H/HePas (susceptible), BALB/c (intermediate) and C57BL/6 (resistant) mice were infected with the CL or Colombian strain of Trypanosoma cruzi, and TNF activity was measured in the sera during the acute phase of the infection. Only serum collected from infected C3H/He mice contained TNF activity. However, TNF activity could be measured in serum of all strains, following LPS infection, indicating that the infection was able to prime macrophages of infected mice to secrete TNF alpha. The TNF alpha/cachectin release in the sera of C3H mice may play a role in the early wasting and death of these mice after Trypanosoma cruzi infection.