RESUMO
The purpose of this study was to investigate the effects of melatonin on selected biomarkers of innate and humoral immune response as well as the antioxidant/oxidant status (superoxide dismutase-SOD and reduced glutathione levels (GSH) to understand whether age-related changes would influence the development of acute Trypanosoma cruzi (T. cruzi) infection. Young- (5 weeks) and middle-aged (18 months) Wistar rats were orally treated with melatonin (gavage) (05 mg/kg/day), 9 days after infection. A significant increase in both SOD activity and GSH levels was found in plasma from all middle-aged melatonin-treated animals. Melatonin triggered enhanced expression of major histocompatibility class II (MHC-II) antigens on antigen-presenting cell (APC) and peritoneal macrophages in all treated animals. High levels of CD4+ CD28-negative T cells (*P<.05) were detected in middle-aged control animals. Melatonin induced a significant reduction (***P<.001) in CD28-negative in CD4+ and CD8+ T cells in middle-aged control animals. Contrarily, the same group displayed upregulated CD4+ CD28+ T and CD8+ CD28+ T cells. Melatonin also triggered an upregulation of CD80 and CD86 expression in all young-treated groups. Significant percentages of B and spleen dendritic cells in middle-aged infected and treated animals were observed. Our data reveal new features of melatonin action in inhibiting membrane lipid peroxidation, through the reduction in 8-isoprostane, upregulating the antioxidant defenses and triggering an effective balance in the antioxidant/oxidant status during acute infection. The ability of melatonin to counteract the immune alterations induced by aging added further support to its use as a potential therapeutic target not only for T. cruzi infection but also for other immunocompromised states.
Assuntos
Antioxidantes/farmacologia , Doença de Chagas , Melatonina/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Envelhecimento , Animais , Antígenos CD28/metabolismo , Doença de Chagas/imunologia , Doença de Chagas/metabolismo , Macrófagos Peritoneais/efeitos dos fármacos , Masculino , Oxirredutases/metabolismo , Ratos , Ratos WistarRESUMO
Retinoblastoma is the most frequent intra-ocular malignant tumor of the childhood, occurring in 1 of 18,000-30,000 live births. Little is known about the causes of sporadic retinoblastoma and only a few authors have investigated the etiologic role of human papillomavirus (HPV), with controversial results. Formalin-fixed, paraffin-embedded tissue blocks containing retinoblastoma were retrieved from the archives of the Department of Pathology at Hospital A C Camargo, São Paulo, Brazil. All patients were treated with enucleation (21 children had both eyes enucleated). Retinoblastoma and, when possible, normal retina of each specimen, were micro-dissected under direct light microscopic visualization by using a PixCell II Laser Capture Micro-dissection System. The DNA quality was evaluated by polymerase chain reaction (PCR) amplification of 110 base pairs fragment of the human ß-globin gene using primers PCO3+/PCO4+. All globin positive specimens were analyzed by PCR for the presence of HPV DNA using consensus primers GP5+/GP6+. A total of 154 specimens were evaluated. Forty-four patients also had normal retinal specimens available for analysis of DNA HPV. The DNA HPV prevalence among all tumor specimens was 4.6% (95% CI 2.0; 8.8) (7 positive specimens/153 adequate specimens). Among normal retinal specimens, the DNA HPV prevalence was 9.1% (95% CI 2.9; 20.5) (4 positive specimens/44 specimens). There was no statistically significant difference between these rates (P = 0.318). Excluding any experimental failure, our results indicate a low prevalence of HPV DNA in retinoblastomas. We were therefore unable to conclude about the association between these oncogenic viruses and this rare pediatric neoplasm.
Assuntos
Papillomaviridae/isolamento & purificação , Infecções por Papillomavirus/epidemiologia , Retinoblastoma/complicações , Retinoblastoma/virologia , Brasil/epidemiologia , Criança , Pré-Escolar , Primers do DNA/genética , DNA Viral/genética , DNA Viral/isolamento & purificação , Feminino , Humanos , Lactente , Masculino , Infecções por Papillomavirus/virologia , Patologia Molecular/métodos , Reação em Cadeia da Polimerase/métodos , PrevalênciaRESUMO
Retinoblastoma is the most frequent intra-ocular malignant tumor of the childhood, occurring in 1 of 18,00030,000 live births. Little is known about the causes of sporadic retinoblastoma and only a few authors have investigated the etiologic role of human papillomavirus (HPV), with controversial results. Formalin-fixed, paraffin-embedded tissue blocks containing retinoblastoma were retrieved from the archives of the Department of Pathology at Hospital A C Camargo, São Paulo, Brazil. All patients were treated with enucleation (21 children had both eyes enucleated). Retinoblastoma and, when possible, normal retina of each specimen, were micro-dissected under direct light microscopic visualization by using a PixCell II Laser Capture Micro-dissection System. The DNA quality was evaluated by polymerase chain reaction (PCR) amplification of 110 base pairs fragment of the human β-globin gene using primers PCO3 +/PCO4+. All globin positive specimens were analyzed by PCR for the presence of HPV DNA using consensus primers GP5+/GP6+. A total of 154 specimens were evaluated. Forty-four patients also had normal retinal specimens available for analysis of DNA HPV. The DNA HPV prevalence among all tumor specimens was 4.6% (95% CI 2.0; 8.8) (7 positive specimens/153 adequate specimens). Among normal retinal specimens, the DNA HPV prevalence was 9.1% (95% CI 2.9; 20.5) (4 positive specimens/44 specimens). There was no statistically significant difference between these rates (P = 0.318). Excluding any experimental failure, our results indicate a low prevalence of HPV DNA in retinoblastomas. We were therefore unable to conclude about the association between these oncogenic viruses and this rare pediatric neoplasm
Assuntos
Masculino , Feminino , Humanos , Lactente , Pré-Escolar , Criança , Brasil/epidemiologia , Papillomaviridae/isolamento & purificação , Infecções por Papillomavirus/epidemiologia , Infecções por Papillomavirus/virologia , Patologia Molecular/métodos , Retinoblastoma/complicações , Retinoblastoma/virologia , Primers do DNA , Prevalência , Reação em Cadeia da Polimerase/métodosRESUMO
Gonadal steroids exert an important influence on the host immune response during infection. Changes resulting from the absence or replacement of gonadal hormones may represent a distinct evolution of a particular parasite. Taking into account the greater susceptibility of males to parasites, the magnitude of the immune response seems to depend on the interaction of many hormones that will act synergistically with other immune cells. The aims of this research were to evaluate the effects of the luck of male sex hormones due to orchiectomy, and the influence of oral administration of melatonin on the immune response of male Wistar rats infected with the Y strain of Trypanosoma cruzi. The percentage of CD3(+) CD4(+) and CD3(+) CD8(+) lymphocyte T cell subsets were evaluated using flow cytometry and the measurement of IL-2 and IL-12. For all parameters examined, a synergistic action of melatonin and orchiectomy on the host's immune response was observed, promoting an effective response against the parasite during the acute phase of infection. These results offer insight into other possibilities for possibly controlling T. cruzi proliferation through melatonin therapy and also the stimulatory effects on host's immune response triggered by the absence of male gonadal steroids during the acute phase of infection.
Assuntos
Doença de Chagas/tratamento farmacológico , Doença de Chagas/imunologia , Melatonina/farmacologia , Melatonina/uso terapêutico , Orquiectomia , Linfócitos T/efeitos dos fármacos , Animais , Complexo CD3/metabolismo , Linfócitos T CD4-Positivos/efeitos dos fármacos , Linfócitos T CD4-Positivos/imunologia , Depressores do Sistema Nervoso Central/farmacologia , Depressores do Sistema Nervoso Central/uso terapêutico , Citometria de Fluxo , Interleucina-12/metabolismo , Interleucina-2/metabolismo , Masculino , Ratos , Ratos Wistar , Linfócitos T/imunologia , Trypanosoma cruziRESUMO
Glucocorticoid hormones have been implicated as an important modulator of Trypanosoma cruzi pathogenesis. Since adrenal steroid hormones play a fundamental role in modulating the immune response, we hypothesized that adrenalectomy affect the course of the experimental T. cruzi infection. This study was undertaken to determine the effects of adrenalectomy during the acute phase of T. cruzi infection. Blood and tissue parasitism, macrophages, nitric oxide (NO) production and IFN-gamma were evaluated in male Wistar rats infected with the Y strain of T. cruzi. Our results show that adrenalectomized rats displayed increased number of blood and heart parasites accompanied by decreases in the total number of peritoneal macrophages and IFN-gamma when compared to controls. Adrenalectomy also reduced the levels of NO released from peritoneal macrophages of infected animals. These results suggest that adrenal corticosteroid insufficiency due to adrenalectomy could be considered an important factor during development of acute phases of experimental Chagas' disease, enhancing pathogenesis through disturbance of the host's immune system.
Assuntos
Glândulas Suprarrenais/fisiologia , Adrenalectomia , Doença de Chagas/imunologia , Macrófagos Peritoneais/metabolismo , Doença Aguda , Corticosteroides/fisiologia , Animais , Contagem de Células , Doença de Chagas/parasitologia , Doença de Chagas/patologia , Coração/parasitologia , Interferon gama/biossíntese , Interferon gama/sangue , Macrófagos Peritoneais/imunologia , Masculino , Camundongos , Miocárdio/patologia , Óxido Nítrico/biossíntese , Parasitemia/imunologia , Parasitemia/parasitologia , Ratos , Ratos WistarRESUMO
Calomys callosus is a wild rodent found naturally infected with different Trypanosoma cruzi strains. In the work described here, groups of male and female C. callosus were subjected to orchiectomy, ovariectomy and sham operation. One month after surgery, animals were inoculated intraperitoneally (i.p.) with 4x10(4) blood trypomastigotes of the "Y" strain of T. cruzi. Parasitemia, triglycerides, nitric oxide (NO) and concanavalin A (ConA)-induced proliferation were evaluated. Parasitemia during the course of infection was significantly higher in infected and sham operated animals as compared to infected orchiectomized animals. The opposite was observed in the ovariectomized and infected group. Orchiectomized and infected animals displayed elevated triglyceride levels, as well as a more vigorous immune response, with higher splenocyte proliferation and elevated concentrations of NO. Ovariectomy resulted in an impaired immune response, as observed by a reduction of splenocyte proliferation and NO concentration. The results suggest a pivotal role for gonadal hormones in the modulation of triglyceride levels and the magnitude of the immune response during the acute phase of T. cruzi infection.
Assuntos
Doença de Chagas/imunologia , Doença de Chagas/parasitologia , Sigmodontinae , Triglicerídeos/sangue , Trypanosoma cruzi/patogenicidade , Animais , Células Cultivadas , Modelos Animais de Doenças , Suscetibilidade a Doenças , Feminino , Interações Hospedeiro-Parasita/imunologia , Imunidade Celular , Injeções Intraperitoneais , Ativação Linfocitária , Masculino , Óxido Nítrico , Orquiectomia/efeitos adversos , Orquiectomia/veterinária , Ovariectomia/efeitos adversos , Ovariectomia/veterinária , Parasitemia/epidemiologia , Fatores Sexuais , Sigmodontinae/sangue , Sigmodontinae/imunologia , Sigmodontinae/parasitologia , Sigmodontinae/cirurgia , Trypanosoma cruzi/crescimento & desenvolvimentoRESUMO
An increased level of plasma corticosterone is one manifestation of severe environmental or physiologic stress. The stress response mediated by the hypothalamic-pituitary-adrenal axis is already known to suppress immunoglobulin production and to impair immune function, but there are few studies relating stress and plasma corticosterone to the outcome of Trypanosoma cruzi infection. In this study, male Wistar rats were infected with the Y strain of T. cruzi and then subjected to repetitive stress by exposure to ether vapor for 1min twice a day during the acute phase of infection. Stressed animals showed decreased lytic antibody activity and lowered levels of peritoneal macrophages. Despite an increase in the weight of the spleen, histological analyses demonstrated tissue alterations, the presence of amastigote nests, and a complete absence of activated lymphoid follicles. These results suggest that stress-induced increases in plasma corticosterone can suppress the immune response and worsen tissue injury during the acute phase of T. cruzi infection.
Assuntos
Doença de Chagas/imunologia , Corticosterona/sangue , Estresse Fisiológico/imunologia , Análise de Variância , Animais , Doença de Chagas/sangue , Doença de Chagas/complicações , Cariometria , Macrófagos Peritoneais/imunologia , Masculino , Tamanho do Órgão , Ratos , Ratos Wistar , Baço/imunologia , Baço/patologia , Estresse Fisiológico/complicaçõesRESUMO
Among more than 200 human papillomavirus (HPV) types presumed to exist, 18 "high-risk" HPV types are frequently found in anogenital cancer. The best studied types are HPV-16 and 18, which are only distantly related to one another and form two separate phylogenetic branches, each including six closely related types. HPV-30, 53, 56, and 66 form a third phylogenetic branch unrelated to HPV-16 and 18. Worldwide comparison of HPV-16 and 18 isolates revealed a distribution of variant genomes that correlated with the geographic origin and the ethnicity of the infected cohort and led to the concept of unique African, European, Asian, and Native American HPV-16 and 18 variants. Here, we address the question whether similar phylogenies are found for HPV-53, 56, and 66 by determining the sequence of the long control regions (LCR) of these HPVs in samples from Europe, Asia, and Africa, and from immigrant societies in North and South America. Phylogenetic trees calculated from point mutations and a few insertions/deletions affecting 2-4.2% of the nucleotide sequences were distinct for each of the three HPVs and divergent from HPV-16 and 18. In contrast to the "star-phylogenies" formed by HPV-16 and 18 variants, 44 HPV-53 isolates represented nine variants, which formed two deep dichotomic branches reminiscent of the beginning split into two new taxa, as recently observed for subtypes of HPV-44 and 68. A total of 66 HPV-56 isolates represented 17 variants, which formed three branches preferentially containing European, Asian, and African variants. Variants of a fourth branch, deeply separated from the other three, were characterized by a 25 bp insertion and created a dichotomy rather than star-like phylogeny. As it contained isolates from cohorts in all continents, it may have evolved before the spread of humans into all continents. 18 of 31 HPV-66 isolates represented the prototype clone, which was found in all parts of the world, while the remaining 13 clones formed 11 branches without any geographic association. Our findings confirm the notion of a quantitatively limited genomic diversity of each HPV type with some correlation to the geographic origin of the sample. In addition, we observed in some variants of these three HPV types mutations that affect the amino acid sequence of the E6 oncoproteins and the L1 capsid protein, supporting the possibility of immunogenic and oncogenic diversity between variants of any HPV type.
Assuntos
Variação Genética , Genoma Viral , Papillomaviridae/classificação , Papillomaviridae/genética , Filogenia , Vírus da Doença Aleutiana do Vison , Sequência de Bases , Primers do DNA , Amplificação de Genes , Humanos , Dados de Sequência Molecular , Papillomaviridae/patogenicidade , Reação em Cadeia da PolimeraseRESUMO
Activation of the hypothalamus-pituitary-adrenal axis plays a major role in the suppression of the immune system. We have investigated the effects of repetitive stress on Wistar rats infected with the Y strain of Trypanosoma cruzi and a control group that underwent stressor stimuli by exposure to ether vapor for one minute twice a day. Repetitive stress resulted in an elevated number of circulating parasites accompanies by deep tissue disorganization, and cardiac histopathological alterations. The infected and stressed group displayed a decrease in body weight, and an increased parasite burden in heart tissue, and adrenal glands. Histological analysis of the heart also showed a moderate to severe diffused mononuclear inflammatory process. These results suggest that repetitive stress could be considered an important factor during development of experimental Chagas' disease, enhancing pathogenesis through disturbance of the host's immune system.