Assuntos
Doença de Chagas/imunologia , Complicações Parasitárias na Gravidez/imunologia , Animais , Doença de Chagas/sangue , Suscetibilidade a Doenças , Feminino , Interferon gama/sangue , Interleucina-12/sangue , Camundongos , Camundongos Endogâmicos BALB C , Músculos/imunologia , Músculos/parasitologia , Gravidez , Complicações Parasitárias na Gravidez/sangue , Resultado da Gravidez , Células Th1/imunologiaRESUMO
Gamma-interferon (IFN-gamma) production, the hallmark of the Th1 immune response, has been shown to play a central role in the resistance to Trypanosoma cruzi infections, in particular when produced in the very early acute infection. BALB/c mice infected with T. cruzi, Tulahuén strain, reach high parasitemias during the acute phase, and their spleen cells release IFN-gamma in the second week of the infection, while those of the resistant C3H strain produce the cytokine earlier, at 2 days post-infection (pi). We studied in the spleen cells supernatants of infected BALB/c and C3H mice, the spontaneous production of cytokines involved in the induction, interleukin (IL)-18 and IL-12 p70, as well as in the downregulation, IL-13 and IL-10, of the Th1 immune response. We found that, at 2 days pi, only C3H mice produced IL-18, while IL-12 p70 was detected in both mouse strains. Moreover, at this time pi splenocytes from BALB/c mice spontaneously produced high amounts of IL-13. At 14 days pi, despite the increased levels of IL-13 and IL-10 detected in C3H mice, they still showed high concentrations of IL-18 and IL-12 p70. In contrast, spleen cells from BALB/c mice did not secrete IL-18, IL-12 p70 and IL-13 at this time pi, but produced higher amounts of IL-10 than C3H mice. Non of these cytokines was found increased in the cell supernatants of chronically infected mice. The addition of lipopolysaccharide (LPS) or Concanavalin A (Con A) to the cell cultures did not enhance the production of IL-18 and IL-12 at the time points tested. On the other hand, at 21 days pi, when parasitemia peaked, an inhibition of both the LPS induced IL-10 release and the IL-13 production upon Con A stimulation was observed in C3H, but not in BALB/c mice. We did not find an increase of IL-18, IL-10, or IL-12 p70 in the serum of the infected mice, despite the high seric IL-12 p40 concentrations reached during the infection. The data show that the different kinetics of the production of these cytokines in the spleen of both mouse strains could have a key role in the in vivo regulation of IFN-gamma production. In these experimental models, early IFN-gamma release and thus resistance to T. cruzi infection, could be related to the combined effect of both IL-18 and IL-12p70 in the absence of IL-13.
Assuntos
Doença de Chagas/imunologia , Interferon gama/biossíntese , Interleucina-13/imunologia , Interleucina-18/imunologia , Trypanosoma cruzi/fisiologia , Doença Aguda , Animais , Doença de Chagas/sangue , Doença de Chagas/parasitologia , Concanavalina A/farmacologia , Modelos Animais de Doenças , Interferon gama/imunologia , Interleucina-10/biossíntese , Interleucina-10/sangue , Interleucina-10/imunologia , Interleucina-12/biossíntese , Interleucina-12/imunologia , Interleucina-13/biossíntese , Interleucina-18/sangue , Interleucina-18/metabolismo , Lipopolissacarídeos/farmacologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C3H , Baço/efeitos dos fármacos , Baço/imunologia , Baço/metabolismo , Células Th1/efeitos dos fármacos , Células Th1/imunologia , Células Th1/metabolismo , Fatores de Tempo , Trypanosoma cruzi/imunologiaRESUMO
Resistance to acute Trypanosoma cruzi infection is mainly associated with a Th1 immune response, characterized by gamma-interferon (IFN-gamma) production and activation of macrophages. The outcome of the Th1 response in the spleen and serum of BALB/c and C3H mice infected with T. cruzi, Tulahuén strain was studied. The levels of interleukin-12 p40 (IL-12 p40) and IFN-gamma, as well as natural killer (NK) cell cytotoxicity were determined at different time-points during the acute phase, and the production of cytokines was also studied in the chronic infection. At 2 days post-infection (pi), spleen cells from C3H mice increased their NK cell activity and the ex vivo spontaneous release of both IL-12 p40 and IFN-gamma. On the other hand, BALB/c mice reached low levels of NK cell cytotoxicity and no IFN-gamma production was detected at this time pi, but the cytokine was released at high amounts in the second week of the infection. Seric IL-12 p40 concentrations showed a 3-fold increase in both mouse strains on the second day pi and remained high throughout the acute phase. However, seric IFN-gamma levels increased during the late acute infection and were higher in BALB/c than in C3H mice. In chronically infected mice IL-12 p40 was as high as in the acute phase in the serum of both strains, but only BALB/c mice still produced IFN-gamma. To the authors' knowledge this is the first report showing the protein levels of IL-12 p40 determined in vivo in acute and chronic T. cruzi infections. The results reveal differences between both mouse strains in the mechanisms controlling the onset and fate of the Th1 response triggered by the parasite and a long lasting pro-inflammatory stimuli.
Assuntos
Doença de Chagas/imunologia , Interferon gama/biossíntese , Interleucina-12/biossíntese , Células Matadoras Naturais/imunologia , Doença Aguda , Animais , Doença Crônica , Técnicas In Vitro , Cinética , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C3H , Especificidade da Espécie , Baço/imunologia , Células Th1/imunologiaRESUMO
Specific antibodies and the activation of phagocytic cells by IFN-gamma are the key elements of the immune response involved in protection of the T. cruzi infected host. The central role of the IFN-gamma in vivo seems to be the activation of the inducible nitric oxide synthetase of macrophages (iNOS) and the production of nitric oxide (NO degree) for the intracellular destruction of the parasite. Interleukin 12 (IL-12), the cytokine that stimulates NK cells for IFN-gamma production, seems to trigger the TH1 response in the acute phase. Other cell types, such as lymphocytes Thy-1+CD4-CD8-, CD4+ and CD8+, are also involved in IFN-gamma production. The down regulation of the TH1 response could in part depend on the decrease in the macrophage activation, as a result of the controlled parasite burden, and on the production of IL-10 and transforming growth factor beta (TGF-beta). The protective TH1 immune response seems to be also related to both the tissue damage and the alterations of the immune response observed during the infection. We studied the kinetics of both NK cell activity, and the production of IL-12 and/IFN-gamma by spleen cells, as well as the seric levels of these cytokines, in BALB/c and C3H mice infected with T. cruzi, Tulahuén strain. In the spleen, we found that the production of IL-12 and the NK cell activity increased in the very early acute infection, and that in C3H the effect was higher than in BALB/c mice. IFN-gamma increased in C3H at the same time, but in the BALB/c strain it increased later in the acute phase. The infection induced a very early increase in the seric levels of IL-12, that remained high throughout the acute phase, in both mouse strains. However, the levels of IFN-gamma in the serum increased a few days before the peak of parasitemia, reaching higher values, and earlier, in BALB/c than in C3H mice. Surprisingly, in the chronic infection IL-12 production remained high in both mouse strains, but IFN-gamma production was only observed in BALB/c mice. The immune response was predominantly TH1 in both mouse strains, in spite of the higher susceptibility of BALB/c compared to C3H. The early control of the parasite burden could be evaluated as the expression of the TH1 response in spleen cells, while the seric levels of IL-12 and IFN-gamma would be related to the induction of tissue damage. Our data indicate that the protective TH1 immune response has a different expression according to the host-parasite relationship, and that the factors controlling the response are of primary importance to determine the quali- and quantitative expression of IL-12/NK/IFN-gamma as well as their involvement in resistance and tissue damage.
Assuntos
Doença de Chagas/imunologia , Interferon gama/fisiologia , Interleucina-12/fisiologia , Células Matadoras Naturais/imunologia , Óxido Nítrico/sangue , Células Th1/imunologia , Trypanosoma cruzi/imunologia , Animais , Doença Crônica , Imunidade Celular , Interferon gama/sangue , Interleucina-12/sangue , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C3H , Óxido Nítrico Sintase/metabolismo , Óxido Nítrico Sintase Tipo II , Especificidade da Espécie , Baço/citologia , Baço/imunologia , Células Th2/imunologia , Trypanosoma cruzi/patogenicidadeRESUMO
The changes in the T cell subsets of the Peyer's patches and the thymus were analyzed in BALB/c mice infected with Trypanosoma cruzi, Tulahuén strain. During the acute stage of the infection both lymphoid organs drastically reduced their cellularity. This was mainly due to the decrease in the immature CD4+CD8+ T cell population in the thymus and in both T and B cells in the Peyer's patches. In the acute infection, few Peyer's patches were found and the histological studies revealed a depletion of the thymic-dependent areas, paralleling the decreased number of cells expressing CD4 and alpha beta T cell receptor. After 14 weeks, in the late stage of the infection, the cellularity and the levels of the T cell subsets studied returned to values similar to those of noninfected mice.
Assuntos
Doença de Chagas/imunologia , Nódulos Linfáticos Agregados/imunologia , Subpopulações de Linfócitos T/patologia , Doença Aguda , Animais , Relação CD4-CD8 , Doença de Chagas/patologia , Citometria de Fluxo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Parasitemia/imunologia , Parasitemia/patologia , Nódulos Linfáticos Agregados/patologia , Timo/imunologia , Timo/patologiaRESUMO
The release of reactive oxygen intermediates (ROI), mediators of inflammatory reactions, was evaluated in murine Trypanosoma cruzi infection. In acutely infected BALB/c mice, spleen cells were stimulated, either with epimastigote or trypomastigote forms of the parasite, and the effect was enhanced by serum from infected mice. Only opsonized parasites triggered the release of ROI by normal mouse cells and this response was several times lower than in infected mice. This seems to indicate that cells from acutely infected mice reacted to T. cruzi and that neither parasites nor serum factors blocked the release of ROI. During the acute stage of the infection, both the parasitemia and the release of ROI by spleen cells were higher in BALB/c than in C3H mice (ROI generated in response to a phagocytic stimulation was 12 and 3 times the normal levels, respectively). In addition, in BALB/c mice infected with different numbers of parasites, the production of ROI was related to parasitemia. On the other hand, during the chronic stage of the infection, the inflammatory reaction in myocardium was greater in C3H than in BALB/c mice, and the increase in ROI production was 30% and 100% above the normal levels in BALB/c and C3H mice, respectively. This suggests that the increased ROI production paralleled the parasite burden in the acute phase, and could be related to inflammatory processes after the control of the parasitemia.
Assuntos
Doença de Chagas/metabolismo , Fagócitos/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Trypanosoma cruzi/imunologia , Doença Aguda , Animais , Doença de Chagas/imunologia , Medições Luminescentes , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C3H , Miocárdio/patologia , Proteínas Opsonizantes/imunologia , Parasitemia/imunologia , Parasitemia/metabolismo , Fagócitos/imunologia , Baço/citologia , Baço/metabolismoRESUMO
The discovery of the superantigens (SAgs) offered new insights on the interaction between microorganisms and the host immune system. Associated to Major Histocompatibility Complex (MHC) class II molecules, SAgs bind to the variable domain of the beta chain (V beta) of the TCR alpha beta engaged in the family specificity of lymphocytes. Therefore, these molecules are able to activate a high number of T lymphocytes as well as surface MHC class II bearing cells, leading to an overriding release of cytokines and inflammatory mediators, which have been related to their toxic effects. Endogenous SAgs are encoded by murine tumor proviruses (Mtv) which are integrated in the genome of mice. Bacteria and viruses produce exogenous SAgs and those related to food poisoning have been widely studied. The presence of parasite SAgs is still unclear and further studies are required to establish their existence and effects on the corresponding infections.
Assuntos
Bactérias/imunologia , Eucariotos/imunologia , Sistema Imunitário/imunologia , Superantígenos/imunologia , Vírus/imunologia , Animais , Humanos , Mediadores da Inflamação/imunologia , Mediadores da Inflamação/metabolismo , Linfocinas/imunologia , Linfocinas/metabolismo , Complexo Principal de Histocompatibilidade/imunologia , Camundongos , Receptores de Antígenos de Linfócitos T/imunologia , Superantígenos/metabolismoRESUMO
The T cell receptor (TCR) V beta repertoire was studied in BALB/c, CBA/HJ, and CBA/J mice experimentally infected with Trypanosoma cruzi. The percentage of expression of 14 V beta chains of the variable domain of the TCR in the thymus and spleen was evaluated. In the thymus of acutely infected with BALB/c and CBA/HJ mice there was an increase in the expression of positively selected V beta families. These changes in the V beta chains usage in the thymus paralleled the enrichment of CD4+ and CD8+ single-positive T cells. During the acute infection, several changes were observed in the peripheral expression of V beta families, such as of V beta 6 in BALB/c (a 36% increase in CD8+ T cells of the corresponding levels of V beta), of V beta 8 in CBA/HJ (a 37% decrease in CD8+ cells), and of V beta chains 8 and 14 in CBA/J mice (V beta 14+CD4+ cells increased 19%, and V beta 8 expression decreased 19 and 33% in CD4+ and CD8+ cells, respectively). In chronically infected BALB/c and CBA/HJ mice, no change in the V beta families was observed, neither in the thymus nor in the spleen. In acutely infected mice, the alterations of the peripheral expression of positively selected V beta families could be due to the stimulation by T. cruzi antigens and/or cytokines; the homeostatic mechanism/s that maintains the selection of the TCR V beta repertoire did not seem to be severely affected during the infections.