Absence of Fas-L aggravates renal injury in acute Trypanosoma cruzi infection

Kidney complications of parasitic diseases

Parasitic agents have been known to cause human disease since ancient times and are endemic in tropical and subtropical regions. Complications of parasitic diseases, including kidney involvement, are associated with worse outcomes. Chagas disease, filariasis, leishmaniasis, malaria and schistosomiasis are important parasitic diseases that can damage the kidney. These diseases affect millions of people worldwide, primarily in Africa, Asia and Latin America, and kidney involvement is associated with increased mortality. The most common kidney complications of parasitic diseases are acute kidney injury, glomerulonephritis and tubular dysfunction. The mechanisms that underlie parasitic disease-associated kidney injury include direct parasite damage; immunological phenomena, including immune complex deposition and inflammation; and systemic manifestations such as haemolysis, haemorrhage and rhabdomyolysis. In addition, use of nephrotoxic drugs to treat parasitic infections is associated with acute kidney injury. Early diagnosis of kidney involvement and adequate management is crucial to prevent progression of kidney disease and optimize patient recovery.

Antiparasitic and anti-inflammatory activities of ß-lapachone-derived naphthoimidazoles in experimental acute Trypanosoma cruzi infection

BACKGROUND

Chagas disease, which is caused by the protozoan Trypanosoma cruzi, is endemic to Latin America and mainly affects low-income populations. Chemotherapy is based on two nitrocompounds, but their reduced efficacy encourages the continuous search for alternative drugs. Our group has characterised the trypanocidal effect of naphthoquinones and their derivatives, with naphthoimidazoles derived from β-lapachone (N1, N2 and N3) being the most active in vitro.

OBJECTIVES

In the present work, the effects of N1, N2 and N3 on acutely infected mice were investigated.

METHODS

in vivo activity of the compounds was assessed by parasitological, biochemical, histopathological, immunophenotypical, electrocardiographic (ECG) and behavioral analyses.

FINDINGS

Naphthoimidazoles led to a decrease in parasitaemia (8 dpi) by reducing the number of bloodstream trypomastigotes by 25-50% but not by reducing mortality. N1 protected mice from heart injury (15 dpi) by decreasing inflammation. Bradycardia was also partially reversed after treatment with N1 and N2. Furthermore, the three compounds did not reverse hepatic and renal lesions or promote the improvement of other evaluated parameters.

MAIN CONCLUSION

N1 showed moderate trypanocidal and promising immunomodulatory activities, and its use in combination with benznidazole and/or anti-arrhythmic drugs as well as the efficacy of its alternative formulations must be investigated in the near future.

Renal dysfunction in Leishmaniasis and Chagas disease coinfection: a case report

Visceral leishmaniasis (VL) is an endemic parasitic disease frequently found in Northeast Brazil and may cause acute kidney injury (AKI) and glomerulonephritis. After appropriate treatment, renal function recovery may occur. We describe the rare case of a patient with VL, who developed severe AKI requiring dialysis and was subsequently diagnosed with Chagas disease coinfection. After specific treatment for VL, there was partial recovery of the renal function, followed by the onset of Chagas disease cardiomyopathy.

Moderate Treadmill Exercise Training Improves Cardiovascular and Nitrergic Response and Resistance to Trypanosoma cruzi Infection in Mice

There is evidence suggesting that exercise training (ET) acts as a factor toward resistance to Trypanosoma cruzi infection. However, the effects of mean arterial pressure (MAP), heart rate (HR), and nitric oxide (NO) during the acute phase of infection has not been elucidated yet. Swiss mice were randomly assigned into four groups: sedentary control (SC, n = 30), trained control (TC, n = 30), sedentary infected (SI, n = 30), and trained infected (TI, n = 30). ET was performed on the treadmill for 9 weeks. After training, the mice were infected with 5 × 10³ trypomastigotes of T. cruzi (Y strain) or PBS. We observed resting bradycardia and improved performance in trained animals compared with sedentary ones. On the 20th day post-infection (DPI), we found a decrease in HR in SI animals compared to TI animals (699.73 ± 42.37 vs. 742.11 ± 25.35 bpm, respectively, P < 0.05). We also observed increased production of NO in cardiac tissue on the 20th DPI in the SI group, normalized in TI group (20.73 ± 2.74 vs. 6.51 ± 1.19 μM, respectively). Plasma pro-inflammatory cytokines (IL-12, TNF-α, IFN-γ,) and MCP-1 were increased in SI animals, but decreased in TI animals. The increase in parasitemia on the 15th and 17th DPI in the SI group was attenuated in the TI group. Our results suggest that previous ET plays a preventive role in resistance to T. cruzi infection, modulating cardiovascular aspects, inflammatory reaction, and NO levels of infected mice.

Impairment of T cell function in parasitic infections

In mammals subverted as hosts by protozoan parasites, the latter and/or the agonists they release are detected and processed by sensors displayed by many distinct immune cell lineages, in a tissue(s)-dependent context. Focusing on the T lymphocyte lineage, we review our present understanding on its transient or durable functional impairment over the course of the developmental program of the intracellular parasites Leishmania spp., Plasmodium spp., Toxoplasma gondii, and Trypanosoma cruzi in their mammalian hosts. Strategies employed by protozoa to down-regulate T lymphocyte function may act at the initial moment of naïve T cell priming, rendering T cells anergic or unresponsive throughout infection, or later, exhausting T cells due to antigen persistence. Furthermore, by exploiting host feedback mechanisms aimed at maintaining immune homeostasis, parasites can enhance T cell apoptosis. We will discuss how infections with prominent intracellular protozoan parasites lead to a general down-regulation of T cell function through T cell anergy and exhaustion, accompanied by apoptosis, and ultimately allowing pathogen persistence.

Influence of parasite load on renal function in mice acutely infected with Trypanosoma cruzi

BACKGROUND

Chagas disease is a neglected tropical disease caused by Trypanosoma cruzi. Despite the vast number of studies evaluating the pathophysiological mechanisms of the disease, the influence of parasite burden on kidney lesions remains unclear. Thus, the main goal of this work was to evaluate the effect of T. cruzi infection on renal function and determine whether there was a correlation between parasite load and renal injury using an acute experimental model of the disease.

METHODOLOGY/PRINCIPAL FINDINGS

Low, medium and high parasite loads were generated by infecting C57BL/6 mice with 300 (low), 3,000 (medium) or 30,000 (high) numbers of "Y" strain trypomastigotes. We found that mice infected with T. cruzi trypomastigotes show increased renal injury. The infection resulted in reduced urinary excretion and creatinine clearance. We also observed a marked elevation in the ratio of urine volume to kidney and body weight, blood urea nitrogen, chloride ion, nitric oxide, pro- and anti-inflammatory cytokines and the number of leukocytes in the blood and/or renal tissues of infected mice. Additionally, we observed the presence of the parasite in the cortical/medullary and peri-renal region, an increase of inflammatory infiltrate and of vascular permeability of the kidney. Overall, most renal changes occurred mainly in animals infected with high parasitic loads.

CONCLUSIONS/SIGNIFICANCE

These data demonstrate that T. cruzi impairs kidney function, and this impairment is more evident in mice infected with high parasitic loads. Moreover, these data suggest that, in addition to the extensively studied cardiovascular effects, renal injury should be regarded as an important indicator for better understanding the pan-infectivity of the parasite and consequently for understanding the disease in experimental models.