Vânia Brazão

Universidade de Ribeirão Preto, Entre Rios, São Paulo, Brazil

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Publications (17)45.77 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Pregnancy is known to induce a transient depression of maternal cell-mediated immunity, to prevent rejection of the fetus, while at the same time it keeps adequate maternal host defense mechanisms to fight infection. Presently, the aims of this paper were to investigate a possible endocrine and immunologic alterations observed during a successful pregnancy. This study consistently showed that plasma corticosterone levels were significantly higher (P < 0.0001) in pregnant Wistar rats than in virgin female. An increased number of peritoneal macrophage was also detected in pregnant females when compared to non-pregnant ones. Macrophages play an important role in the production of bioactive proteins and lipids such as nitric oxide. Then, in support of the latter, the present study showed increased levels of endogenous NO in pregnant rats when compared to non pregnant ones, thereby mediating the vasodilatation process of normal gestation. Furthermore, our FACS analysis clearly indicated the correlation between reduced CD161 expression on NK cells (P < 0.0001) in pregnant rats when compared to virgin females. It was found that pregnancy appears to be associated with depressed cell immunity, as evidenced by a significant inhibition of lymphocyte proliferation. Understanding the immunological paradox of maternal tolerance, as well as the hormonal modulation of the immune environment during pregnancy is essential for future studies to investigate the potential for these processes to be modulated by diet or effective therapeutics during pregnancy.
    Immunobiology 09/2014; · 2.81 Impact Factor
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    ABSTRACT: Chagas disease induces a strong immune response and L-arginine is an essential amino acid which plays an important role in homeostasis of the immune system. The aims of this study were to evaluate parasitemia, corticosterone levels, production of nitric oxide (NO), fetal morphological measurements, and histothology of heart and placenta. Twenty pregnant Wistar rats (180-220g) were grouped in: pregnant control (PC), pregnant control and L-arginine supplied (PCA), pregnant infected (PI), pregnant infected and L-arginine supplied (PIA). Females were infected with 1x10(5) trypomastigotes of the Y strain (3rd day of pregnancy). Animals were supplied with 21 mg of L-arginine/Kg/day during 14 days. PIA showed significant decreased levels of corticosterone and parasitemia. For control groups, any alteration in NO production was found with L-arginine supplementation; for PIA, enhanced nitrite concentrations were observed as compared to PI. Weights and lengths of fetuses were higher in L-arginine treated and infected pregnant rats as compared to untreated ones. Placental weight from the PIA group was significantly increased when compared to PI. In L-arginine treated animals, cardiac tissue showed reduced amastigote burdens. PIA and PI displayed similar placental parasitism. Based on these results, L-arginine supplementation may be potentially useful for the protection against T. cruzi during pregnancy.
    Experimental Parasitology 04/2014; · 2.15 Impact Factor
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    ABSTRACT: BACKGROUND & AIMS: The occurrence of infectious disease processes during pregnancy has significant effects on maternal health and can lead to adverse pregnancy outcomes. The aim of the present study was to examine the potential role of zinc treatment during Trypanosoma cruzi infection in pregnant animals. METHODS: Female Wistar rats weighing 180-200 g were used in all experiments. Production of nitric oxide, peritoneal macrophages counts, and concentrations of IFN-γ and TNF-α were measured, and the potential protective effects of zinc on fetal development were assessed at 14-day post-infection. RESULTS: Nitric oxide concentrations were higher in pregnant zinc-treated animals than in their untreated counterparts, despite similar levels of the macrophages, IFN-γ and TNF-α. Zinc therapy was associated with a significant reduction in parasitemia and cardiac parasite burden. Higher placental and birth weights were observed in animals given prenatal zinc supplementation compared to untreated animals. CONCLUSIONS: These data confirm the critical importance of adequate zinc intake during the peri-conceptional period and indicate that zinc has an effective role in preventing adverse outcomes of pregnancy and reducing the risk of common infections such as Chagas' disease.
    Clinical nutrition (Edinburgh, Scotland) 10/2012; · 3.27 Impact Factor
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    ABSTRACT: Melatonin has been reported to play a fundamental role in T-cell immunoregulation. Control of Trypanosoma cruzi parasitism during the acute phase of infection is considered to be critically dependent on direct macrophage activation by cytokines. The aim of this work was to evaluate the influence of exogenous melatonin treatment and the influences exerted by sexual hormones during the acute phase of the experimental Chagas' disease in rats. With melatonin treatment, orchiectomized animals (CMOR and IMOR) displayed the highest concentrations of IFN-γ and TNF-α. On the 7th day post-infection, untreated and treated orchiectomized animals (IOR and IMOR) showed an enhanced number of peritoneal macrophages. Nitric oxide levels were also increased in untreated and treated orchiectomized (IOR and IMOR) when compared to the other groups, with or without LPS. Our data suggest that melatonin therapy associated with orchiectomy induced a stimulating effect on the immune response to the parasite.
    Research in Veterinary Science 12/2011; 93(2):819-25. · 1.77 Impact Factor
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    ABSTRACT: Melatonin by exhibiting antioxidant, anti-aging, and immunomodulatory properties favorably modulate the immune function, protecting the hosts from several infectious diseases. Zinc is an essential trace element important for the efficiency of the immune system in reason of its widespread role in the activity of enzymes, transcription factors and cytokines. The etiology of Chagas' disease, caused by a protozoan parasite Trypanosoma cruzi, has been the focus of considerable discussion, although chronic phase still remains not fully understood. This study showed that zinc and melatonin treatment did not affect the percentage of both CD4+ and CD8+ T lymphocytes subsets in chronically infected animals. Increased levels of IL-2 and IL-10, as well as, enhanced thymocyte proliferation in T. cruzi infected groups under zinc and melatonin therapy was observed as compared to untreated group. Conversely, during the chronic phase of infection, macrophages counts were reduced in melatonin and zinc-melatonin treated animals. The combined actions of zinc and melatonin have beneficial effects in counteracting parasite-induced immune dysregulation, protecting animals against the harmful actions of chronic T. cruzi infection. Furthermore, our results provide an experimental basis for further studies on the role of immunomodulatory therapies.
    Cytokine 09/2011; 56(3):627-32. · 2.52 Impact Factor
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    ABSTRACT: During the course of infection by Trypanosoma cruzi, the host immune system is involved in distinct, complex interactions with the endocrine system, and prolactin (PRL) is one of several hormones involved in immunoregulation. Although intensive studies attempting to understand the mechanisms that underlie Chagas' disease have been undertaken, there are still some pieces missing from this complex puzzle. Because data are scarce concerning the role of PRL involvement in Chagas' disease and taking into account the existence of crosstalk between neuroendocrine hormones and the immune system, the current study evaluates a possible up-regulation of the cellular immune response triggered by PRL in T. cruzi-infected rats and the role of PRL in reversing immunosuppression caused by the parasitic infection. The data shown herein demonstrate that PRL induces the proliferation of T lymphocytes, coupled with an activation of macrophages and the production of nitric oxide (NO), leading to a reduction in the number of blood trypomastigotes during the peak of parasitemia. During the acute phase of T. cruzi infection, an enhancement of both CD3+CD4+ and CD3+CD8+ T cell populations were observed in infected groups, with the highest numbers of these T cell subsets found in the infected group treated with PRL. Because NO is a signaling molecule involved in a number of cellular interactions with components of the immune system and the neuroendocrine system, PRL can be considered an alternative hormone able to up-regulate the host's immune system, consequently lowering the pathological effects of a T. cruzi infection.
    Veterinary Parasitology 04/2011; 181(2-4):139-45. · 2.38 Impact Factor
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    ABSTRACT: Understanding the mechanisms responsible for mediating the effects of stress on Trypanosoma cruzi infection is crucial for determining the full impact of stress on Chagas' disease and for devising effective interventions. Dehydroepiandrosterone (DHEA), a steroid hormone synthesized from pregnenolone, is secreted by the adrenal cortex in response to stress. Although its physiologic role has not been fully defined, DHEA has been shown to modulate immune function. In the present study, we evaluated the levels of corticosterone and the ability of T. cruzi infection to modulate the expression of Th2 cytokines in Wistar rats with chronic Chagas' disease submitted to repetitive stress. The animals submitted to stress displayed enhanced levels of corticosterone as compared to control counterparts. Stress and infection triggered the most elevated concentrations of corticosterone. DHEA significantly reduced corticosterone levels for infected and stressed animals with DHEA. The infected animals displayed enhanced levels of IL-10 and IL-4 as compared to control ones. Stress combined with infection triggered the higher levels of IL-10 and IL-4. DHEA alone and combined with infection and stress significantly increased IL-10 and IL-4 levels. Then, this study might provide additional clues about factors that regulate some of the immunoregulatory aspects of T. cruzi infection and might offer new opportunities for therapeutic interventions.
    Experimental Parasitology 01/2011; 127(1):31-5. · 2.15 Impact Factor
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    ABSTRACT: The ability of the gonadal hormones to influence diverse immunological functions during the course of several infections has been extensively studied in the latest decades. Testosterone has a suppressive effect on immune response of vertebrates and increases susceptibility toward numerous parasitic diseases. Dehydroepiandrosterone is an abundant steroid hormone secreted by the human adrenal cortex and it is considered potent immune-activator. In this paper, it was examined the effects of DHEA and testosterone supplementation in the thymic atrophy in rats infected with Trypanosoma cruzi, by comparing blood parasitism, thymocyte proliferation, TNF-alpha and IL-12 levels. Our data point in the direction that DHEA treatment triggered enhanced thymocyte proliferation as compared to its infected counterparts and reduced production of TNF-alpha during the acute phase of infection. Oppositely, the lowest values for cells proliferation and IL-12 concentrations were reached in testosterone-supplied animals. The combined treatment testosterone and DHEA improves the effectiveness of the host's immune response, reducing blood parasites and the immunosuppressive effects of male androgens besides increasing IL-12 concentrations and decreasing TNF-alpha levels.
    Research in Veterinary Science 03/2010; 89(1):98-103. · 1.77 Impact Factor
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    ABSTRACT: 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.
    Journal of Pineal Research 09/2009; 47(3):271-6. · 7.30 Impact Factor
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    ABSTRACT: Chagas' disease is considered the sixth most important neglected tropical disease worldwide. Considerable knowledge has been accumulated concerning the role of zinc on cellular immunity. The steroid hormone dehydroepiandrosterone (DHEA) is also known to modulate the immune system. The aims of this paper were to investigate a possible synchronization of their effects on cytokines and NO production and the resistance to Trypanosoma cruzi during the acute phase of infection. It was found that zinc, DHEA or zinc and DHEA supplementation enhanced the immune response, as evidenced by a significant reduction in parasitemia levels. Zinc and DHEA supplementation exerted additive effects on the immune response by elevation of macrophage counts, and by increasing concentrations of IFN-gamma and NO.
    Immunobiology 08/2009; 215(5):427-34. · 2.81 Impact Factor
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    ABSTRACT: Dehydroepiandrosterone (DHEA) has long been considered as a precursor for many steroid hormones. It also enhances the immune responses against a wide range of viral, bacterial, and parasitic pathogens. The aims of this work were to evaluate the influences of exogenous DHEA treatment on Wistar rats infected with the Y strain of Trypanosoma cruzi during the acute and its influence on the chronic phase of infection. Animals were subcutaneous treated with 40 mg/kg body weight/day of DHEA. DHEA treatment promoted increased lymphoproliferative responses as well as enhanced concentrations of NO and IL-12. So, we point in the direction that our results validate the utility of the use of DHEA as an alternative therapy candidate against T. cruzi.
    Veterinary Parasitology 05/2009; 163(1-2):27-32. · 2.38 Impact Factor
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    ABSTRACT: Zinc is an essential nutritional component required for normal development and maintenance of immune functions. The possible effects of zinc in upregulating the host immune response during the acute and chronic phases of experimental Chagas' disease were evaluated. In young, infected and Zn-supplemented animals, higher concentrations of IFN-gamma and NO were observed. During the chronic phase, decreased concentrations of NO and IFN-gamma were found for older infected animals that received Zn supplementation. For young animals, hearts from Zn-supplemented groups displayed reduced inflammatory infiltrate, heart weight and number of amastigote burdens. For older, infected and Zn-supplemented animals amastigote nests were absent with reduced inflammatory cell infiltrate. This study identifies a potentially novel therapeutic approach that could control the parasite load during acute phase of disease, consequently preventing the deleterious, parasite-elicited responses observed during chronic phase.
    Experimental Parasitology 11/2008; 121(1):105-9. · 2.15 Impact Factor
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    ABSTRACT: The effect of repetitive stress during acute infection with Trypanosoma cruzi (T. cruzi) on the chronic phase of ensuing Chagas' disease was the focus of this investigation. The aim of this study was to evaluate in Wistar rats the influence of repetitive stress during the acute phase of infection (7 days) with the Y strain of T. cruzi on the chronic phase of the infection (at 180 days). Exposure to ether vapor for 1 min twice a day was used as a stressor. Repetitive stress enhanced the number of circulating parasites and cardiac tissue disorganization, from a moderate to a severe diffuse mononuclear inflammatory process and the presence of amastigote burden in the cardiac fibers. Immunological parameters revealed that repetitive stress triggered a reduced concanavalin A induced splenocyte proliferation in vitro with major effects on the late chronic phase. Serum interleukin-12 concentration decreased in both stressed and infected rats in the early phase of infection although it was higher on 180 days post-infection. These results suggest that repetitive stress can markedly impair the host's immune system and enhance the pathological process during the chronic phase of Chagas' disease.
    Stress (Amsterdam, Netherlands) 11/2008; 12(2):144-51. · 3.21 Impact Factor
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    ABSTRACT: The ability of gonadal hormones to influence and induce diverse immunological functions during the course of a number of parasitic infections has been extensively studied in the latest decades. Dehydroepiandrosterone and its sulfate are the most abundant steroid hormones secreted by the human adrenal cortex and are considered potent immune-activators. The effects of orchiectomy on the course of Trypanosoma cruzi infection in rats, treated and untreated with DHEA were examined, by comparing blood and cardiac parasitism, macrophage numbers, nitric oxide and IFN-gamma levels. Orchiectomy enhanced resistance against infection with elevated numbers of macrophages, enhanced concentrations of NO and IFN-gamma and reduced amastigote burdens in heart when compared to control animals. DHEA replacement exerted a synergistic effect, up-modulating the immune response. Male sex steroids appear to play fundamental role in determining the outcome of disease, through the regulation and modulation of the activity of the immune response.
    Experimental Parasitology 08/2008; 120(3):249-54. · 2.15 Impact Factor
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    ABSTRACT: It is well recognized that zinc is an essential trace element for all organisms, influencing growth and affecting the development and integrity of the immune system. It is also well known that the protective response against Trypanosoma cruzi depends on both innate and acquired immunity and for the control of the parasite load and host survival, the participation of special cells such natural killer (NK), T and B lymphocytes and macrophages are required. So the aims of this study were to evaluate the effects of zinc supplementation on the host's immune response infected with T. cruzi. Our data point in the direction that zinc supplementation triggered enhanced thymocyte and splenocyte proliferation as compared to unsupplied group of animals. It is also important to emphasize that interleukin-12 (IL-12) participates in the resistance to several intracellular pathogens including T. cruzi. Our findings demonstrate an enhanced production of IL-12 during the acute phase of infection in zinc-supplied groups. So we conclude that zinc supplementation leads to an effective host's immune response by up-modulating the host's immune response, thus contributing in the reduction of blood parasites and the harmful pathogenic effects of the experimental Chagas' disease.
    Veterinary Parasitology 07/2008; 154(1-2):32-7. · 2.38 Impact Factor
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    ABSTRACT: Dehydroepiandrosterone (DHEA) enhances immune responses against a wide range of viral, bacterial, and parasitic pathogens. In a previous study, we reported that administration of DHEA significantly decreased the numbers of blood parasites in Trypanosoma cruzi experimental infection. The present study was undertaken to determine the effectiveness of DHEA in reducing the severity of acute phase T. cruzi infection of male and female Wistar rats. Animals were treated subcutaneously with 40 mg/kg body weight/day of DHEA. The concentration of nitric oxide (NO) was determined in spleen peritoneal cavity. Interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) were determined in the sera of uninfected and infected animals. DHEA treatment augments NO production for both sexes after in vitro LPS treatment for uninfected animals. Infection triggered enhanced NO levels although not significant. IL-2 and IFN-gamma were detectable in higher concentrations in treated and infected rats of both genders when compared to untreated controls. These data suggest that DHEA may have a potent immunoregulatory function that can affect the course of T. cruzi infection.
    Veterinary Parasitology 06/2008; 153(3-4):238-43. · 2.38 Impact Factor
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    ABSTRACT: It is well recognized that zinc is an essential trace element, influencing growth and affecting the development and integrity of the immune system. The use of oligoelements as zinc can be considered a tool in modulating the effectiveness of the immune response. In this work zinc was daily and orally supplied in male Wistar rats infected with the Y strain of Trypanosoma cruzi. Parasitemia was evaluated and a significant reduction on blood parasites was observed. In order to check some immunological parameters peritoneal macrophages were counted revealing higher percentages for zinc supplied group. Consequently enhanced concentrations of IFN-gamma was found and for the first time NO was evaluated in T. cruzi infected animals under the influence of zinc therapy, revealing enhanced concentrations when compared to unsupplied counterparts. We conclude that zinc is able to up-regulate the host's immune response against parasite replication.
    Experimental Parasitology 05/2008; 118(4):549-54. · 2.15 Impact Factor

Publication Stats

89 Citations
45.77 Total Impact Points

Institutions

  • 2014
    • Universidade de Ribeirão Preto
      Entre Rios, São Paulo, Brazil
  • 2008–2012
    • University of São Paulo
      • Faculdade de Ciências Farmacêuticas de Ribeirão Preto (FCFRP)
      São Paulo, Estado de Sao Paulo, Brazil
  • 2009
    • Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo
      San Paulo, São Paulo, Brazil