Effects of ghrelin supplementation on the acute phase of Chagas disease in rats.

BACKGROUND: Trypanosoma cruzi is the causative agent of Chagas disease, which is endemic to subtropical and tropical Americas. The disease treatment remains partially ineffective, involving therapies directed to the parasite as well as palliative strategies for the clinical manifestations. Therefore, novel candidates for disease control are necessary. Additionally, strategies based on parasite inhibition via specific targets and application of compounds which improve the immune response against the disease is welcomed. Ghrelin is a peptide hormone pointed as a substance with important cardioprotective, vasodilatory, anti-apoptotic, anti-oxidative and immune modulatory functions. The aims of this study were to evaluate the immunomodulatory effects of ghrelin in male Wistar rats infected with the Y strain of T. cruzi. METHODS: In order to delineate an immune response against T. cruzi mediated by ghrelin, we evaluated the following parameters: quantification of blood and cardiac parasites; analysis of cell markers (CD3+, CD8+, NK, NKT, CD45RA+, macrophage and RT1B+); nitric oxide (NO) production; lymphoproliferation assays; splenocyte apoptosis; and INF-γ, IL-12 and IL-6 quantification in sera. RESULTS: The animals infected with T. cruzi and supplemented with ghrelin demonstrated an upregulated pattern in macrophage and NO production, whereas an anti-inflammatory response was observed in T cells and cytokines. The low response against T. cruzi mediated by T cells probably contributed to a higher colonization of the cardiac tissue, when compared to infected groups. On the other side, the peptide decreased the inflammatory infiltration in cardiac tissue infected with T. cruzi. CONCLUSIONS: Ghrelin demonstrated a dual function in animals infected with T. cruzi. Further studies, especially related to the decrease of cardiac tissue inflammation, are needed in order to determine the advantages of ghrelin supplementation in Chagas disease, mostly for populations from endemic areas.

Does Prolactin treatment trigger imunoendocrine alterations during experimental T. cruzi infection?

Prolactin (PRL) is a pleiotropic polypeptide hormone produced by the anterior pituitary gland and negatively controlled by dopamine. Some researchers have associated the immune regulatory functions of PRL with some infectious diseases like Toxoplasma gondii and T. cruzi. This work aimed to analyze the possible immuno-modulatory effects of this hormone through the subcutaneous administration of PRL during the experimental Chagas disease. On the 14th day post-infection (dpi), PRL triggered increased percentages of NK cells in treated infected animals as compared to the infected and untreated ones. For early and late apoptosis, our results showed that in chronically infected groups, PRL counteracted splenocyte apoptosis as revealed by the reduced percentages of both, early and late apoptosis. Reduced percentages of spleen CD4+ and CD8+ T cells were detected in infected PRL treated rats (60 days post-infection). Concerning to B cells, a significant increased percentage of these cells was found for all PRL treated infected animals (14th dpi), but no statistically significant alteration was observed on the 60th days post-infection. Furthermore, PRL treatment triggered a significant increase in the percentage of CD4+ T lymphocytes IFN-γ producers, while on the 60th dpi, a reduced percentage of IFN-γ in these cells was observed in prolactin-treated rats compared to infected and untreated ones. Enhanced serum IL-12 levels were detected in infected and PRL treated subjects (60th dpi). Only on 7th day post-infection, the flow cytometric analysis of CFSE-stained CD3+ T cells showed an enhanced proliferation of polyclonal stimulated T cells in PRL-treated and infected animals. In this study, we demonstrated that PRL can influence many aspects of the immune response during the experimental Chagas' disease, and this substance could be used as a supporting trial along with the conventional drug treatment.

The treatment with selenium increases placental parasitismin pregnant Wistar rats infected with the Y strain of Trypanosoma cruzi.

Selenium (Se) is an essential micronutrient in the diet of mammals and has an important role in the immune function. Selenium is a key element in selenoproteins involved in the in the maintenance of the antioxidant defense. Diet with selenium is beneficial for the treatment of diseases correlated with high levels of oxidative stress, also observed in the Chagas disease. Chagas disease is a neglected disease caused by the protozoan Trypanosoma cruzi and several research groups are focused on the illness treatment. Immunomodulation of the infection using microelements is an important tool to avoid deleterious effects of the Chagas disease. Therefore, our objective was to evaluate the effects of selenium supplementation on pregnant Wistar rats infected with T. cruzi. Selenium treatment stimulated the weight and length of fetuses and placentas allied to the decrease of blood parasitemia. However, selenium demonstrated a low influence on T cells, diminishing the B cell population (CD45RA+). Moreover, the production of pro-inflammatory cytokines was downregulated under selenium administration. Low pro-inflammatory cytokines levels probably are related to the increase in the number of amastigote nests in infected and treated animals. Thus, selenium supplementation during pregnancy could impair the local placental immune response. Further studies are necessary to assess the interaction between selenium and the acute Chagas' disease during pregnancy, which will base future supplementation strategies.

Is the adaptive immune response in murine Trypanosoma cruzi infection influenced by zinc supplementation?

Chagas disease afflicts 7 to 8 million people worldwide and congenital Chagas' disease usually leads to changes in the maternal environment, culminating in fetal adaptations. Several articles have described the importance of micronutrients on pregnancy, which is sensitive to infections. In Trypanosoma cruzi endemic regions, the Chagas disease is aggravated by the lack of micronutrients in an average diet, to which pregnant women are more susceptible. The aim of this study was to evaluate distinct T cells phenotypes and intracellular cytokines by flow cytometry in pregnant Wistar rats under zinc therapy during experimental Chagas' disease. Twenty female Wistar rats were infected with 1×105 blood trypomastigotes (Y strain) and 30days after infection the animals were mated and grouped: pregnant infected (PI-n=5), pregnant infected/zinc supplied (PIZ-n=5), pregnant control (PC-n=5), control/zinc supplied (PCZ-n=5). Zinc supplementation: 20mg of zinc/Kg/day (gavage) for 18days followed by euthanasia. The immune parameters showed: decreased percentages of CD62LlowCD44high surface marker for infected and treated group (PIZ) when compared to PI (p<0.05). Concerning to T regulatory cells (Treg cells), a significantly lower percentage of splenic Treg cells was found in the infected and treated group (PIZ) as compared to the PI group (p<0.05). The expression of the co-stimulatory molecule CD28+ displayed a significant reduced percentage in TCD8+ for infected and zinc treated group (PIZ) as compared to (PI). The percentages of CD4+/CD11a+ T cells subsets were lower on PIZ as compared to PI. Concerning to CD45RA+ (B lymphocytes) analysis, infected pregnant and treated group (PIZ) showed a significant decrease in CD45RA percentage when compared to (PI) (p<0.05). The intracellular cytokine profiles for TCD4+ and TCD8+ producing IL-4 and IFN-γ revealed that zinc treated and untreated infected pregnant group (PI and PIZ) displayed increased cytokines concentrations as compared to zinc treated and untreated pregnant controls (PC and PCZ). Our data revealed the involvement of zinc as a signaling molecule in the modulation of the inflammatory process and immune response which occurs during pregnancy of T. cruzi infected rats. Zinc acted in a dual fashion, modulating the host's immune response in a way to protect the organism against the deleterious effects of the infection and an overwhelming pro-inflammatory response during pregnancy.

Endocrine and immune system interactions during pregnancy.

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 aim of this paper was to investigate a possible endocrine and immunologic alteration 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 macrophages 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.

Does L-arginine availability during the early pregnancy alters the immune response of Trypanosoma cruzi infected and pregnant Wistar rats?

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 histology of heart and placenta. Twenty pregnant Wistar rats (180-220 g) 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 1×10(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 Trypanosoma cruzi during pregnancy.

Protective actions of melatonin against heart damage during chronic Chagas disease.

Chronic cardiomyopathy is the most important clinical form of Chagas disease, and it is characterised by myocarditis that is associated with fibrosis and organ dysfunction. Alternative treatment options are important tools to modulate host immune responses. The main goal of this work was to evaluate the anti-inflammatory actions of melatonin during the chronic phase of Chagas disease. TNF-α, IL-10 and nitrite concentrations were evaluated as predictive factors of immune modulation. Creatine phosphokinase-MB (CK-MB), cardiac inflammatory foci and heart weight were assessed to evaluate the efficacy of the melatonin treatment. Male Wistar rats were infected with 1×10(5) blood trypomastigotes of the Y strain of Trypanosoma cruzi and kept untreated for 60 days to mimic chronic infection. After this period, the rats were orally treated with melatonin 50mg/kg/day, and the experiments were performed 90, 120, and 180 days post-infection. Melatonin treatment significantly increased the concentration of IL-10 and reduced the concentrations of NO and TNF-α produced by cardiomyocytes. Furthermore, it led to decreased heart weight, serum CK-MB levels and inflammatory foci when compared to the untreated and infected control groups. We conclude that melatonin therapy is effective at protecting animals against the harmful cardiac inflammatory response that is characteristic of chronic T. cruzi infection.

Zinc and pregnancy: Marked changes on the immune response following zinc therapy for pregnant females challenged with Trypanosoma cruzi.

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.