Detection of Tc13 antigens of Trypanosoma cruzi in cardiac and skeletal muscle of BALB/c mice with acute Chagas’ infection

GARCIA, GA; GARAVAGLIA, PA; ARNAIZ, MR; ESTEVA, MI

Mar del Plata

Congreso; IX Congreso de Protozoología y Enfermedades Parasitarias.; 2011

Detection of Tc13 antigens of Trypanosoma cruzi in cardiac and skeletal muscle of BALB/c mice with acute Chagas’ infection Gabriela Andrea García, Patricia Andrea Garavaglia, María Rosa Arnaiz and Mónica Inés Esteva Instituto Nacional de Parasitología “Dr. Mario Fatala Chaben”- ANLIS “Dr. Carlos G. Malbrán Mice and humans infected with Trypanosoma cruzi, the etiological agent of Chagas’ disease, develop strong immune responses to trans-sialidase (TS)-derived antigens from the parasite.Tc13 is a TS family protein bearing 5 amino acid (EPKSA) repeats at its C- terminal region. We have previously shown that Tc13 antigens mainly induce non-protective immune responses and that EPKSA domain interacts with b1-adrenergic receptor displaying an agonist-like activity in rat myocardium in vitro. All these facts suggest that these antigens may be involved in the pathogenesis of Chagas’ disease. The objective of the present study was to evaluate by immuno-gold electron microscopy the presence of Tc13 antigens in the target organs of Chagas’ disease, heart and skeletal muscle, in T. cruzi infected mice. BALB/c mice were infected intra-peritoneally with 500 bloodstream trypomastigotes of Tulahuen strain of T. cruzi and were sacrificed in the acute phase of the infection (21 dpi). Lowicryl-embedded thin sections from paraformaldehyde-fixed heart and skeletal muscle tissues from control and infected mice were reacted with a rabbit anti-EPKSA serum, followed by incubation with 10 nm-gold-labelled anti-rabbit IgG. Quantification of the immunoreaction was performed by counting the number of gold particles in the micrographs at a final magnification of x 15,000. The number of gold particles per m2 in heart and skeletal muscle sections were significantly higher in infected than in control mice (6.96 +/- 0.88 vs 3.40 +/- 0.72, p=0.02 in heart sections, 7.34 +/- 1.02 vs 2.58 +/- 0.53, p= 0.0018 in muscle sections). Immuno-labelling was not associated to the membrane either in heart or skeletal muscle. Gold label was uniformly distributed in skeletal muscle sections; however, cardiac tissue exhibited higher labeling density in myofibers than in mitochondria. In conjunction with our previous findings, the presence of deposits of Tc13 antigens in the organs affected by the parasite support the hypothesis that the Tc13 family protein is mainly involved in physiological mechanisms deleterious to the host.