RESUMO
Tuberculosis (TB) remains the world's leading cause of morbidity and mortality. Although Mycobacterium bovis bacillus Calmette-Guérin (BCG) is the only vaccine currently in use, its efficacy is highly variable. It has been suggested that early antigenic presentation is a pivotal event leading to a better immune response in TB vaccine models. To investigate this further, we compared in vitro cell-mediated immune responses in the context of early sensitization with TB (i.e. healthy adults vaccinated with BCG when they were young, HD; n = 25) to those in its absence (i.e., newborns with naïve immunity to TB, UV; n = 10) by challenging mononuclear cells with BCG Moreau. After 48 hours, CD4+ and CD8+ T cells were harvested from both groups and stained for PD-1/CD25/ FOXP3. In addition, supernatants were assayed for a broad range of cytokines using an array system. The HD group showed robust reactivity to Protein Purified Derivative and BCG while the naïve, UV group did not. Similarly, in terms of PD-1 expression and Treg cells (CD4+/CD25high(+)/FOXP3+), only the HD group showed higher levels in CD4 lymphocytes. Otherwise, only the UV group showed expression of CD25dim+ as an activation marker dependent on BCG infection. In terms of cytokines, the HD group showed higher levels of Th1 (IL-2/TNF-α/IFN-γ) and regulatory (IL-10) profiles, with monocytes, but not Tr1 cells, acting as the main source of IL-10. Taken together, our results highlight critical roles of early sensitization with TB in mounting cell-mediated immune responses.
Assuntos
Vacina BCG/administração & dosagem , Vacina BCG/imunologia , Leucócitos Mononucleares/imunologia , Subpopulações de Linfócitos T/imunologia , Adolescente , Adulto , Brasil , Células Cultivadas , Meios de Cultura/química , Citocinas/análise , Fatores de Transcrição Forkhead/análise , Voluntários Saudáveis , Humanos , Subunidade alfa de Receptor de Interleucina-2/análise , Leucócitos Mononucleares/química , Receptor de Morte Celular Programada 1/análise , Subpopulações de Linfócitos T/química , Adulto JovemRESUMO
BACKGROUND: Loss or mutations of the BRCA1 gene are associated with increased risk of breast and ovarian cancers and with prostate cancer (PCa) aggressiveness. Previously, we identified GADD153 as a target of BRCA1 protein, which increases doxorubicin sensitivity in human p53 -/- PCa cells (PC3). Considering that p53 is a crucial target in cancer therapy, in this work we investigated p53 role in the regulation of transcription of GADD153. METHODS: We performed reverse transcription quantitative PCR (RT-qPCR), western blot and luciferase assays to analyze GADD153 and/or BRCA1 expression in response to ultraviolet or doxorubicin exposure in PC3 p53 stable-transfected cells and LNCaP (p53+/+) cells. BRCA1 protein recruitment to GADD153 promoter was studied by chromatin immunoprecipitation-qPCR. To assess expression of BRCA1 and/or p53 target genes, we used a panel of stable-transfected PCa cell lines. We finally analyzed these genes in vivo using BRCA1-depleted PCa xenograft models. RESULTS: We found that GADD153 was highly induced by doxorubicin in PC3 cells; however, this response was totally abolished in LNCaP (p53wt) and in p53-restituted PC3 cells. Furthermore, BRCA1 protein associates to GADD153 promoter after DNA damage in the presence of p53. Additionally, we demonstrated that BRCA1 and/or p53 modulate genes involved in DNA damage and cell cycle regulation (cyclin D1, BLM, BRCA2, DDB2, p21(WAF1/CIP1), H3F3B, GADD153, GADD45A, FEN1, CCNB2), EMT (E-cadherin, ß-catenin, vimentin, fibronectin, slug, snail) and Hedgehog pathways (SHH, IHH, DHH, Gli1, PATCH1). Furthermore, xenograft studies demonstrated that BRCA1 knockdown in PC3 cells increased tumor growth and modulated these genes in vivo. CONCLUSIONS: Although BRCA1 induces GADD153 in a p53 independent manner, p53 abolished GADD153 induction in response to DNA damage. In addition, several important PCa targets are modulated by BRCA1 and p53. Altogether, these data might be important to understand the therapy response of PCa patients.
Assuntos
Proteína BRCA1/metabolismo , Neoplasias da Próstata/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Animais , Proteína BRCA1/genética , Ciclo Celular/genética , Linhagem Celular Tumoral , Dano ao DNA , Ouriços/genética , Ouriços/metabolismo , Xenoenxertos , Humanos , Masculino , Camundongos , Neoplasias da Próstata/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais , Fator de Transcrição CHOP/metabolismo , Transcrição Gênica , Proteína Supressora de Tumor p53/genéticaRESUMO
Leishmaniasis is a group of important parasitic diseases affecting millions worldwide. To understand more clearly the quality of T helper type 1 (Th1) response stimulated after Leishmania infection, we applied a multiparametric flow cytometry protocol to evaluate multifunctional T cells induced by crude antigen extracts obtained from promastigotes of Leishmania braziliensis (LbAg) and Leishmania amazonensis (LaAg) in peripheral blood mononuclear cells from healed cutaneous leishmaniasis patients. Although no significant difference was detected in the percentage of total interferon (IFN)-γ-producing CD4(+) T cells induced by both antigens, multiparametric flow cytometry analysis revealed clear differences in the quality of Th1 responses. LbAg induced an important proportion of multifunctional CD4(+) T cells (28% of the total Th1 response evaluated), whereas LaAg induced predominantly single-positive cells (68%), and 57% of those were IFN-γ single-positives. Multifunctional CD4(+) T cells showed the highest mean fluorescence intensity (MFI) for the three Th1 cytokines assessed and MFIs for IFN-γ and interleukin-2 from those cells stimulated with LbAg were significantly higher than those obtained after LaAg stimulation. These major differences observed in the generation of multifunctional CD4(+) T cells suggest that the quality of the Th1 response induced by L. amazonensis antigens can be involved in the mechanisms responsible for the high susceptibility observed in L. amazonensis-infected individuals. Ultimately, our results call attention to the importance of studying a Th1 response regarding its quality, not just its magnitude, and indicate that this kind of evaluation might help understanding of the complex and diverse immunopathogenesis of American tegumentary leishmaniasis.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Leishmaniose Cutânea/imunologia , Adulto , Antígenos de Protozoários/administração & dosagem , Linfócitos T CD4-Positivos/classificação , Citocinas/biossíntese , Feminino , Citometria de Fluxo , Humanos , Interferon gama/biossíntese , Interleucina-2/biossíntese , Leishmania braziliensis/imunologia , Leishmania mexicana/imunologia , Leishmaniose Cutânea/parasitologia , Masculino , Pessoa de Meia-Idade , Especificidade da Espécie , Células Th1/imunologia , Fator de Necrose Tumoral alfa/biossíntese , Adulto JovemRESUMO
Whole-cell and soluble extracts of Leishmania promastigotes have both been used as skin test antigens and have also been tested as vaccine candidates. However, the differences in antigenicity between soluble and particulate Leishmania fractions are not known. We evaluated in vitro responses of PBMC from 30 American tegumentary leishmaniasis (ATL) patients and seven noninfected donors to different antigen preparations from Leishmania promastigotes, namely Leishmania amazonensis and L. braziliensis whole-cell extracts, as well as soluble and particulate fractions of L. amazonensis. All Leishmania antigen preparations stimulated significantly higher proliferation and interferon (IFN)-gamma production (but not interleukin (IL)-10 production) in PBMC from the leishmaniasis patients than in cells from the control subjects. The L. braziliensis whole-cell extract stimulated significantly higher cell proliferation and IFN-gamma production than the L. amazonensis whole-cell extract in the group of patients but not in the control group. This result can be explained by the fact that the patients were infected with L. braziliensis. Again in the group of patients, the PBMC proliferative responses as well as the levels of IFN-gamma and IL-10 stimulated by L. amazonensis whole-cell extract were significantly greater than those elicited by the L. amazonensis soluble fraction but were not significantly different from those elicited by the L. amazonensis particulate fraction. We found a higher antigenicity of the particulate fraction as compared to the soluble fraction, what suggests that the antigens present in the particulate fraction account for most of the antigenicity of whole-cell Leishmania promastigote antigen extracts.
Assuntos
Antígenos de Protozoários/imunologia , Leishmania/imunologia , Leishmaniose Cutânea/imunologia , Leucócitos Mononucleares/imunologia , Animais , Divisão Celular/imunologia , Humanos , Interferon gama/imunologia , Interleucina-10/imunologia , Leishmania/ultraestrutura , Leishmania braziliensis/imunologia , Leishmania braziliensis/ultraestrutura , Microscopia Eletrônica , SolubilidadeRESUMO
A positive reaction to the leishmanin skin test (LST) indicates previous contact with Leishmania antigens and is a useful criterion for the diagnosis of cutaneous leishmaniasis. In leishmaniasis vaccine trials, selection of volunteers has always been based on skin testing. During 1999 we performed a randomized controlled study in order to evaluate the immunogenicity of the LST. Fifty-nine (29 male and 30 female) healthy volunteer undergraduate students from the Medical School of Volta Redonda, Rio de Janeiro State, Brazil, with no evidence of previous infection with Leishmania, were randomly assigned into 2 groups: 29 subjects received LST and 30 received a placebo (merthiolate-phosphate-buffered saline). All volunteers received LST 41 d after the first injection of LST or placebo. Blood samples were taken immediately before the applications of LST or placebo for the assessment of Leishmania antigen-induced proliferation and cytokine production in peripheral blood mononuclear cell cultures. A significant increase in proliferative responses to L. braziliensis (P < 0.005) and L. amazonensis (P = 0.01) antigens as well as in L. braziliensis antigen-induced interferon-gamma production (P < 0.01) followed the application of LST but not the administration of the placebo. A single LST application is therefore able to induce Leishmania-specific cell-mediated immune responses. This observation should be considered in human trials of candidate vaccines against leishmaniasis.
Assuntos
Antígenos de Protozoários/imunologia , Leishmaniose Cutânea/imunologia , Adulto , Brasil , Método Duplo-Cego , Feminino , Humanos , Leishmaniose Cutânea/prevenção & controle , Masculino , Testes CutâneosRESUMO
This study was aimed at evaluating the immunogenicity of a vaccine composed of killed Leishmania amazonensis promastigotes using several different protocols in a randomized, double-blind and controlled trial design in order to select one of them for further efficacy trials. One hundred and fourteen leishmanin skin test (LST)-negative healthy volunteers were allocated into eight groups that received either two or three deep intramuscular injections of vaccine at doses of 180, 360 and 540 microg or similar injections of placebo. Cell-mediated immune responses were evaluated before and after vaccination by means of LST as well as proliferative responses and cytokine production in Leishmania antigen-stimulated peripheral blood mononuclear cell cultures. The majority of the subjects who actually received vaccine converted to positive LST (89.5%). On the other hand, none of the subjects who received placebo converted to positive LST. Proliferative responses and production of interferon-gamma and interleukin-2 were significantly higher after vaccination than before vaccination in all groups, including those that received placebo. The dose of 360 microg provided the highest LST conversion rate (100%), as well as the greatest increase in interferon-gamma and interleukin-2 production after vaccination.
Assuntos
Leishmania/imunologia , Leishmaniose Cutânea/imunologia , Leishmaniose Cutânea/prevenção & controle , Vacinas Protozoárias/imunologia , Adolescente , Adulto , Animais , Antígenos de Protozoários/imunologia , Células Cultivadas , Citocinas/biossíntese , Método Duplo-Cego , Feminino , Humanos , Leucócitos Mononucleares/imunologia , Ativação Linfocitária , Masculino , Pessoa de Meia-Idade , Vacinas Protozoárias/administração & dosagem , Testes Cutâneos , VacinaçãoRESUMO
An atypical case of acquired immunodeficiency syndrome-associated mucocutaneous lesions due to Leishmania braziliensis is described. Many vacuolated macrophages laden with amastigote forms of the parasite were found in the lesions. Leishmanin skin test and serology for leishmaniasis were both negative. The patient was resistant to therapy with conventional drugs (antimonial and amphotericin B). Interestingly, remission of lesions was achieved after an alternative combined therapy of antimonial associated with immunotherapy (whole promastigote antigens). Peripheral blood mononuclear cells were separated and stimulated in vitro with Leishmania antigens to test the lymphoproliferative responses (LPR). Before the combined immunochemotherapy, the LPR to leishmanial antigens was negligible (stimulation index - SI=1.4). After the first course of combined therapy it became positive (SI=4.17). The antigen responding cells were predominantly T-cells (47.5%) most of them with CD8+ phenotype (33%). Very low CD4+ cells (2.2%) percentages were detected. The increased T-cell responsiveness to leishmanial antigens after combined therapy was accompanied by interferon-g (IFN-g) production as observed in the cell culture supernatants. In this patient, healing of the leishmaniasis lesions was associated with the induction of a specific T-cell immune response, characterized by the production of IFN-g and the predominance of the CD8+ phenotype among the Leishmania-reactive T-cells.
Assuntos
Síndrome da Imunodeficiência Adquirida/complicações , Imunoterapia , Leishmania braziliensis , Leishmaniose Mucocutânea/terapia , Linfócitos T/imunologia , Síndrome da Imunodeficiência Adquirida/imunologia , Animais , Imunidade Celular , Leishmaniose Mucocutânea/imunologiaRESUMO
This study was designed to evaluate the immunogenicity of autoclaved and nonautoclaved preparations of a vaccine composed of whole antigens from killed promastigotes of Leishmania amazonensis. Leishmanin skin-test (LST)-negative volunteers were immunized with either autoclaved or nonautoclaved vaccine preparations (32 and 36 subjects, respectively) that had been maintained at 4 degrees C for one year before the onset of this trial. Immunological tests were performed two days before and 40 days after vaccination. The LST conversion rates induced by the autoclaved and nonautoclaved vaccines were significantly different: 59% and 83%, respectively. Leishmania antigen-stimulated proliferative responses of peripheral blood mononuclear cells (PBMC) were significantly higher after vaccination than before vaccination in both groups. The CD8+ subset was predominant over the CD4+ subset among the leishmania-reactive cells after vaccination in both groups. The production of IFN-gamma by the leishmania antigen-stimulated PBMC was significantly higher after vaccination than before vaccination in the group receiving the nonautoclaved vaccine but not in the autoclaved vaccine group. IL-2 was found both before and after vaccination with no differences between its levels in these time points in either group. IL-4 was not detected for either group during the study period.
Assuntos
Antígenos de Protozoários/imunologia , Leishmaniose Cutânea/prevenção & controle , Vacinas Protozoárias/imunologia , Adulto , Animais , Eletroforese em Gel de Poliacrilamida , Feminino , Citometria de Fluxo , Humanos , Interferon gama/biossíntese , Interleucina-2/biossíntese , Interleucina-4/biossíntese , Leishmania braziliensis/imunologia , Masculino , Fenótipo , Testes Cutâneos , EsterilizaçãoRESUMO
Patients with American cutaneous leishmaniasis were studied before therapy (active lesion) and at the end of therapy (cured patients). Assays of lymphocyte proliferative responses of peripheral blood mononuclear cells induced in vitro by Leishmania braziliensis promastigote antigens (Lb) were performed. Antigen-stimulated cells were harvested for CD4 and CD8 phenotype analysis and the levels of gamma interferon (IFN-gamma) and interleukin 4 (IL-4) produced were also determined in the culture supernatants. Two different patterns of Lb-induced T cell responses were observed: a) predominance of responding CD4+ cells and mixed type 1 and type 2 cytokine production (IFN-gamma and IL-4) during the active disease, and b) similar proportions of responding CD4+ and CD8+ cells, and type 1 cytokine production (presence of IFN-gamma and very low IL-4) at the end of therapy (healed lesions). This last pattern is probably associated with a beneficial T cell response.
Assuntos
Leishmaniose Cutânea/imunologia , Linfócitos T CD4-Positivos , Linfócitos T CD8-Positivos , Humanos , Interferon gama , Interleucina-4RESUMO
Patients with American cutaneous leishmaniasis were studied before therapy (active lesion) and at the end of therapy (cured patients). Assays of lymphocyte proliferative responses of peripheral blood mononuclear cells induced in vitro by Leishmania braziliensis promastigote antigens (Lb) were performed. Antigen-stimulated cells were harvested for CD4 and CD8 phenotype analysis and the levels of gamma interferon (IFN-gamma) and interleukin 4 (IL-4) produced were also determined in the culture supernatants. Two different patterns of Lb-induced T cell responses were observed: a) predominance of responding CD4+ cells and mixed type 1 and type 2 cytokine production (IFN-gamma and IL-4) during the active disease, and b) similar proportions of responding CD4+ and CD8+ cells, and type 1 cytokine production (presence of INF-gamma and very low IL-4) at the end of therapy (healed lesions). This last pattern is probably associated with a beneficial T cell response.