RESUMO
Evidences indicate that pregnancy can alter the Ag-specific T-cell responses. This work aims to evaluate the impact of pregnancy on the in vitro HIV-1-specific immune response. As compared with non-pregnant patients, lower T-cell proliferation and higher IL-10 production were observed in T-cell cultures from pregnant patients following addition of either mitogens or HIV-1 antigens. In our system, the main T lymphocyte subset involved in producing IL-10 was CD4(+)FoxP3(-). Depletion of CD4(+) cells elevated TNF-α and IFN-γ production. Interestingly, the in vitro HIV-1 replication was lower in cell cultures from pregnant patients, and it was inversely related to IL-10 production. In these cultures, the neutralization of IL-10 by anti-IL-10 mAb elevated TNF-α release and HIV-1 replication. In conclusion, our results reveal that pregnancy-related events should favor the expansion of HIV-1-specific IL-10-secreting CD4(+) T-cells in HIV-1-infected women, which should, in the scenario of pregnancy, help to reduce the risk of vertical HIV-1 transmission.
Assuntos
Infecções por HIV/complicações , Infecções por HIV/imunologia , HIV-1/imunologia , Complicações Infecciosas na Gravidez/imunologia , Subpopulações de Linfócitos T/imunologia , Adulto , Estudos de Casos e Controles , Feminino , Antígenos HIV/administração & dosagem , Infecções por HIV/transmissão , Infecções por HIV/virologia , HIV-1/fisiologia , Humanos , Técnicas In Vitro , Recém-Nascido , Transmissão Vertical de Doenças Infecciosas/prevenção & controle , Interleucina-10/biossíntese , Ativação Linfocitária , Gravidez , Complicações Infecciosas na Gravidez/virologia , Subpopulações de Linfócitos T/virologia , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/virologia , Replicação Viral/imunologia , Adulto JovemRESUMO
Our objective was to evaluate the in vitro functional profile of T cells from uninfected neonates born from HIV-1-infected pregnant women who controlled (G1) or not (G2) the virus replication. We demonstrated that the lymphoproliferation of T cell to polyclonal activators was higher in the G2 as compared with G1. Nevertheless, no detectable proliferative response was observed in response to HIV-1 antigens in both neonate groups. Cytokine dosage in the supernatants of these polyclonally activated T cell cultures demonstrated that, while IL-10 was the dominant cytokine produced in G1, Th17-related cytokines were significantly higher in G2 neonates. The higher Th17 phenotype tendency in G2 was related to high production of IL-23 by lipopolysaccharide-activated monocyte-derived dendritic cells from these neonates. Our results demonstrated immunological disorders in uninfected neonates born from viremic HIV-1-infected mothers that can help to explain why some of these children have elevated risk of clinical morbidity and mortality due to pathological hypersensitivity.
Assuntos
Infecções por HIV/imunologia , HIV-1/imunologia , Células Th17/imunologia , Adulto , Proliferação de Células , Células Cultivadas , Citocinas/sangue , Citocinas/imunologia , Células Dendríticas/imunologia , Feminino , Sangue Fetal/citologia , Soropositividade para HIV/imunologia , Humanos , Recém-Nascido , Leucócitos Mononucleares/imunologia , Contagem de Linfócitos , Gravidez , Linfócitos T/citologia , Linfócitos T/imunologia , Células Th1/imunologia , Adulto JovemRESUMO
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
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
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
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
The number of HIV-infected young women has been increasing since the beginning of the AIDS epidemic. The objective of the present study was to investigate the impact of anti-retroviral treatment (ART) of HIV-1-infected pregnant women (PW) on cytokine profile of uninfected neonates. Our results demonstrated that higher levels of IL-1ß and TNF-α associated with lower IL-10 production were detected in the plasma obtained from neonates born from ART-treated PW. Furthermore, the production of TNF- α and IFN-γ was also significantly higher in polyclonally-activated T cells from those neonates. This elevated pro-inflammatory pattern detected by these activated-T cells was not associated to HIV-1 antigens sensitization. Finally, ART-exposed neonates showed to be born with lower weight, and it was inversely correlated with maternal peripheral TNF-a level. In summary, the data presented here suggest a significant disturbance in cytokine network of HIV-1-uninfected neonates exposed to potent anti-retroviral schemes during pregnancy.
Assuntos
Citocinas/imunologia , Infecções por HIV/tratamento farmacológico , HIV/imunologia , Complicações Infecciosas na Gravidez/tratamento farmacológico , Linfócitos T/imunologia , Adulto , Antígenos Virais/imunologia , Terapia Antirretroviral de Alta Atividade/efeitos adversos , Peso Corporal/efeitos dos fármacos , Células Cultivadas , Feminino , Infecções por HIV/imunologia , Humanos , Imunidade Materno-Adquirida/efeitos dos fármacos , Recém-Nascido , Ativação Linfocitária/efeitos dos fármacos , Gravidez , Complicações Infecciosas na Gravidez/imunologia , Adulto JovemRESUMO
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
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
Infection with Trypanosoma cruzi causes expansion of subcutaneous (SLN) and atrophy of mesenteric (MLN) lymph nodes. Here we show that excision of MLN increased parasitemia in T. cruzi-infected mice. We then studied how apoptosis of MLN cells affects immune responses to infection. T cell apoptosis increased in the MLN compared to SLN in T. cruzi-infected mice. Absolute numbers of naïve T cells decreased, and activated T cells failed to accumulate in MLN during infection. In addition, activated T cells from MLN produced less IL-2, IFN-gamma, IL-4, and IL-10 than T cells from SLN. Treatment with IL-4 or with caspase-9 inhibitor increased the recovery of viable T cells in vitro. Treatment with caspase-9 inhibitor also increased the production of cytokines by MLN T cells from infected mice. Moreover, injection of a pan caspase inhibitor prevented MLN atrophy during T. cruzi infection. Caspase-9, but not caspase-8, inhibitor also reduced MLN atrophy and increased the recovery of naïve and activated T cells from MLN. These findings indicate that caspase-mediated apoptosis and defective cytokine production are implicated in MLN atrophy and affect immune responses to T. cruzi infection.
Assuntos
Apoptose/imunologia , Doença de Chagas/imunologia , Linfonodos/imunologia , Mesentério/imunologia , Pele/imunologia , Linfócitos T/imunologia , Animais , Atrofia , Caspases/efeitos dos fármacos , Caspases/imunologia , Caspases/metabolismo , Citocinas/biossíntese , Inibidores Enzimáticos/farmacologia , Ensaio de Imunoadsorção Enzimática , Citometria de Fluxo , Linfonodos/microbiologia , Linfonodos/patologia , Ativação Linfocitária/imunologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Linfócitos T/microbiologia , Linfócitos T/patologia , Trypanosoma cruziRESUMO
Caspases, a family of cysteinyl-aspartate-specific proteases, induce apoptosis but are also involved in signal transduction in live cells. Caspase activation and apoptosis in T lymphocytes occur following infection with parasites and might affect immune responses. Rapid progress has occurred in the development and testing of caspase inhibitors and other apoptosis blockers, which are potentially useful for treating diseases associated with the pathogenic effects of apoptosis. Pharmacological approaches and the use of genetically modified hosts can be combined in research strategies to understand how apoptosis and caspase signaling affect the immune system.
Assuntos
Caspases/fisiologia , Doença de Chagas/imunologia , Transdução de Sinais/fisiologia , Animais , Apoptose , Doença de Chagas/patologia , Citocinas/fisiologia , Humanos , Imunidade Inata , Ativação Linfocitária , Macrófagos/fisiologia , Linfócitos T/imunologiaRESUMO
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
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
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.