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.

In vitro leishmanicidal and cytotoxic activities of the glycoalkaloids from Solanum lycocarpum (Solanaceae) fruits

Leishmaniasis is an infection caused by a protozoan parasite of the genus Leishmania and is the second most prevalent parasitic protozoal disease after malaria in the world. We report the in vitro leishmanicidal activity on promastigote forms of Leishmania amazonensis and cytotoxicity, using LLCMK2 cells, of the glycoalkaloids from the fruits of Solanum lycocarpum, determined by colorimetric methods. The alkaloidic extract was obtained by acid-base extraction; solamargine and solasonine were isolated by silica-gel chromatography, followed by reversed-phase HPLC final purification. The alkaloidic extract, solamargine, solasonine, as well as the equimolar mixture of the glycoalkaloids solamargine and solasonine displayed leishmanicidal activity against promastigote forms of L. amazonensis, whereas the aglycone solasodine was inactive. After 24 and 72 h of incubation, most of the samples showed lower cytotoxicities (IC50 6.5 to 124 μM) as compared to leishmanicidal activity (IC50 1.1 to 23.6 μM). The equimolar mixture solamargine/solasonine was the most active with an IC50 value of 1.1 μM, after 72 h. Likewise, solamargine was the most active after 24 h with an IC50 value of 14.4 μM, both in comparison with the positive control amphotericin B.

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.