Administration of granulocyte colony‐stimulating factor induces immunomodulation, recruitment of T regulatory cells, reduction of myocarditis and decrease of parasite load in a mouse model of chronic Chagas disease cardiomyopathy

Abstract

Chagas disease, caused by Trypanosoma cruzi infection, is a leading cause of heart failure in Latin American countries. In a previous study, we showed beneficial effects of granulocyte colony-stimulating factor (G-CSF) administration in the heart function of mice with chronic T. cruzi infection. Presently, we investigated the mechanisms by which this cytokine exerts its beneficial effects. Mice chronically infected with T. cruzi were treated with human recombinant G-CSF (3 courses of 200 μg/kg/d for 5 d). Inflammation and fibrosis were reduced in the hearts of G-CSF-treated mice, compared with the hearts of vehicle-treated mice, which correlated with decreased syndecan-4, intercellular adhesion molecule-1, and galectin-3 expressions. Marked reductions in interferon-γ and tumor necrosis factor-α and increased interleukin-10 and transforming growth factor-β were found after G-CSF administration. Because the therapy did not induce a Th1 to Th2 immune response deviation, we investigated the role of regulatory T (Treg) cells. A significant increase in CD3(+)Foxp3(+) cells was observed in the hearts of G-CSF-treated mice. In addition, a reduction of parasitism was observed after G-CSF treatment. Our results indicate a role of Treg cells in the immunosuppression induced by G-CSF treatment and reinforces its potential therapeutic use for patients with Chagas disease.

Depletion of regulatory T cells decreases cardiac parasitosis and inflammation in experimental Chagas disease

“…Anti-CD25 treatment had not previously been observed to significantly impact the development of myocarditis in T. cruzi –infected mice, even though Treg depletion with anti-GITR was shown to cause increased inflammation and parasitosis in the myocardium (Mariano et al 2008). As an alternative approach, the effect of Treg recruitment on the pathogenesis of experimental Chagas disease was examined using treatment with granulocyte colony-stimulatory factor, and found to reduce both parasite load and the severity of myocarditis (Vasconcelos et al 2013). Transfer of Tregs from mice immunized with a recombinant T. cruzi protein (rSSP4) into mice that were infected with T. cruzi reduced cardiac inflammation and prolonged survival, but increased blood parasitemia and cardiac parasitosis (Flores-Garcia et al 2013).…”

Therapeutic effects of sphingosine kinase inhibitor N,N-dimethylsphingosine (DMS) in experimental chronic Chagas disease cardiomyopathy

“…Images were digitized using a color digital video camera (CoolSnap, Montreal, Canada) adapted to a BX41 microscope (Olympus, Tokyo, Japan). Morphometric analyses were performed using the software Image Pro Plus v.7.0 (Media Cybernetics¸ San Diego, CA), as described before 46 .…”

“…Sections of formalin-fixed paraffin embedded hearts were used for detection of galectin-3 expression by immunofluorescence as described before 46 . Sections were incubated overnight with anti-galectin-3, diluted 1:50 (Santa Cruz Biotechnology, Santa Cruz, CA) followed by incubation, for 1 h, with Alexa fluor 633 (1:200) (Molecular Probes, Carlsbad, CA) Nuclei were stained with 4,6-diamidino-2-phenylindole (Vector Laboratories, Burlingame, CA).…”

“…Primers were designed based on the literature 47 , and the quantification of parasite load was performed as described previously 46 . To calculate the number of parasites per milligram of tissue, each plate contained an 8-log standard curve of DNA extracted from trypomastigotes of the Colombian T. cruzi strain in duplicate.…”

Genetic Vaccination against Experimental Infection with Myotropic Parasite Strains ofTrypanosoma cruzi

“…Analyses were performed essentially as described in [26]. Briefly, heart sections were analyzed by light microscopy after paraffin embedding, followed by standard hematoxylin and eosin staining.…”