Trypanosoma cruzi: The effects of zinc supplementation during experimental infection

Host-directed therapies for parasitic diseases

Parasitic infections are responsible for significant morbidity and mortality throughout the world. Management strategies rely primarily on antiparasitic drugs that have side effects and risk of drug resistance. Therefore, novel strategies are needed for treatment of parasitic infections. Host-directed therapy (HDT) is a viable alternative, which targets host pathways responsible for parasite invasion/survival/pathogenicity. Recent innovative combinations of genomics, proteomics and computational biology approaches have led to discovery of several host pathways that could be promising targets for HDT for treating parasitic infections. Herein, we review major advances in HDT for parasitic disease with regard to core regulatory pathways and their interactions.

The beneficial effect of dietary zinc supplementation on anaemia and immunosuppression in Trypanosoma brucei infected rats

Zinc is an essential trace element crucial for normal development and function of cells mediating nonspecific immunity and protects bio-molecules from oxidative damage. This study was designed to assess the effects of dietary zinc supplementation on anaemia and immunity of trypanosome-infected rats. Thirty rats, divided into five groups (A-E) of 6 each, were used for the study. Parameters used to assess the effect of the supplementation are antibody response to Sheep RBC using direct haemagglutination test, parasitaemia using the rapid matching method, WBC count using the improved Neubauer haemocytometer method, haemoglobin concentration using the cynomethaemoglobin technique while PCV was determined using the microhaematocrit method. The pre-infection supplementation did not prolong the pre-patent period significantly (p > 0.05). However, it significantly (p < 0.05) increased the packed cell volume (PCV), haemoglobin (Hb) concentration, leucocyte count, and antibody titre by day 7 on the supplementation (OTS). Following infection on day 7 OTS, the PCV and Hb decreased but remained significantly (p < 0.05) higher than the infected not supplemented (INS) group, while on day 14 OTS, they maintained a significantly (p < 0.05) higher antibody titre as compared to other groups. On day 21 OTS, theweight of 8 ppm and not infected not supplemented (NINS) groups was significantly (p < 0.05) higher but the relative organ weight of their liver and spleen was significantly (p < 0.05) lower than 2 ppm, 4 ppm and INS groups. On day 21 OTS, the parasitaemia levels of INS group was significantly (p < 0.05) higher than the supplemented groups. From the results, dietary zinc supplementation can be useful in the management of anaemia and immunosupression caused by trypanosomes in rats.

Fluxes in "free" and total zinc are essential for progression of intraerythrocytic stages of Plasmodium falciparum

Dynamic fluxes in the concentration of ions and small molecules are fundamental features of cell signaling, differentiation, and development. Similar roles for fluxes in transition metal concentrations are less well established. Here, we show that massive zinc fluxes are essential in the infection cycle of an intracellular eukaryotic parasite. Using single-cell quantitative imaging, we show that growth of the blood-stage Plasmodium falciparum parasite requires acquisition of 30 million zinc atoms per erythrocyte before host cell rupture, corresponding to a 400% increase in total zinc concentration. Zinc accumulates in a freely available form in parasitophorous compartments outside the food vacuole, including mitochondria. Restriction of zinc availability via small molecule treatment causes a drop in mitochondrial membrane potential and severely inhibits parasite growth. Thus, extraordinary zinc acquisition and trafficking are essential for parasite development.

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.

Nutritional Status Driving Infection by Trypanosoma cruzi: Lessons from Experimental Animals

This paper reviews the scientific knowledge about protein-energy and micronutrient malnutrition in the context of Chagas disease, especially in experimental models. The search of articles was conducted using the electronic databases of SciELO (Scientific Electronic Library Online), PubMed and MEDLINE published between 1960 and March 2010. It was possible to verify that nutritional deficiencies (protein-energy malnutrition and micronutrient malnutrition) exert a direct effect on the infection by T. cruzi. However, little is known about the immunological mechanisms involved in the relationship "nutritional deficiencies and infection by T. cruzi". A hundred years after the discovery of Chagas disease many aspects of this illness still require clarification, including the effects of nutritional deficiencies on immune and pathological mechanisms of T. cruzi infection.

Panorama dos estudos sobre nutrição e doenças negligenciadas no Brasil

O objetivo deste artigo é revisar a literatura acerca da relação entre nutrição e doenças infecciosas negligenciadas em populações brasileiras, focalizando especificamente a doença de Chagas, a malária, a esquistossomose e a leishmaniose visceral. A revisão da literatura foi realizada em janeiro de 2010 a partir de um levantamento bibliográfico nas bases SciELO, LILACS e Medline. Foram captados 293 resumos; dentre estes, 66 foram selecionados para leitura de texto completo e 43 incluídos na revisão. A presente revisão salienta a relevância dos estudos nutricionais no campo da Saúde Coletiva para melhor compreensão dos aspectos envolvidos no risco e prognóstico de malária, esquistossomose, leishmaniose visceral e doença de Chagas. Evidencia-se também certo desbalanceamento na literatura sobre o tema, com muito mais estudos experimentais do que estudos em populações humanas. Ainda que os primeiros sejam essenciais para esclarecer os mecanismos fisiopatológicos subjacentes à relação entre déficits nutricionais e estas doenças, estudos bem delineados em populações humanas são fundamentais para que o conhecimento científico se traduza em ações efetivas para o controle de doenças negligenciadas.