Cruzipain Sulfotopes-Specific Antibodies Generate Cardiac Tissue Abnormalities and Favor Trypanosoma cruzi Infection in the BALB/c Mice Model of Experimental Chagas Disease

Abstract

Trypanosoma cruzi cruzipain (Cz) bears a C-terminal domain (C-T) that contains sulfated epitopes “sulfotopes” (GlcNAc6S) on its unique N-glycosylation site. The effects of in vivo exposure to GlcNAc6S on heart tissue ultrastructure, immune responses, and along the outcome of infection by T. cruzi, were evaluated in a murine experimental model, BALB/c, using three independent strategies. First, mice were pre-exposed to C-T by immunization. C-T-immunized mice (C-TIM) showed IgG2a/IgG1 <1, induced the production of cytokines from Th2, Th17, and Th1 profiles with respect to those of dC-TIM, which only induced IL-10 respect to the control mice. Surprisingly, after sublethal challenge, both C-TIM and dC-TIM showed significantly higher parasitemia and mortality than the control group. Second, mice exposed to BSA-GlcNAc6S as immunogen (BSA-GlcNAc6SIM) showed: severe ultrastructural cardiac alterations while BSA-GlcNAcIM conserved the regular tissue architecture with slight myofibril changes; a strong highly specific humoral-immune-response reproducing the IgG-isotype-profile obtained with C-TIM; and a significant memory-T-cell-response demonstrating sulfotope-immunodominance with respect to BSA-GlcNAcIM. After sublethal challenge, BSA-GlcNAc6SIM showed exacerbated parasitemias, despite elevated IFN-γ levels were registered. In both cases, the abrogation of ultrastructural alterations when using desulfated immunogens supported the direct involvement of sulfotopes and/or indirect effect through their specific antibodies, in the induction of tissue damage. Finally, a third strategy using a passive transference of sulfotope-specific antibodies (IgG-GlcNAc6S) showed the detrimental activity of IgG-GlcNAc6S on mice cardiac tissue, and mice treated with IgG-GlcNAc6S after a sublethal dose of T. cruzi, surprisingly reached higher parasitemias than control groups. These findings confirmed the indirect role of the sulfotopes, via their IgG-GlcNAc6S, both in the immunopathogenicity as well as favoring T. cruzi infection.

Hallmarks of the relationship between host and Trypanosoma cruzi sulfated glycoconjugates along the course of Chagas disease

“…The choice of sub-lethal dose was due to avoid mice mortality in order to analyze the immunopathogenesis is process that occurs in post-acute phase on target tissues pre-exposed to sulfotopes. The murine model was selected because of its susceptibility and auto-reactivity, and it has been previously demonstrated as an outstanding archetype since (a) its immune response profile to T. cruzi infection has long been established to be well-known; (b) the murine strain selected has the ability to imitate both phases, acute and chronic phase models ( Cardoni et al., 1999 ); (c) along the acute phase, it survives increased parasitemia ( Cardoni et al., 1999 ; Wrightsman et al., 1982 ); (d) this strain constitutes a chronic model, which allows one to cautiously examine tissue pathogenesis in the chronic phase ( Cardoni et al., 1999 ; Roggero et al., 2002 ; Soprano et al., 2022 ); and (e) simply, the selected female mice are more resistant to the progress of infection by T. cruzi . Despite the fact that, in T. cruzi infection, the strain does not present as marked polarization as it was observed in Leishmaniasis, BALB/c mice have a biased response towards Th2 ( Huang et al., 1997 ; Kuroda et al., 2002 ).…”

“…On the left part of the figure, it can be observed that in the absence of infection, the sulfotopes’ pre-exposition that determines an immune response and the passive treatment with antibodies specific for sulfotopes determine immunopathogenesis with the consequent characteristics on ultrastructural alterations on cardiac muscle tissues. On the right part of the figure, it can be observed that the sulfotopes’ pre-exposition and the passive treatment with antibodies specific for sulfotopes, followed by challenge with trypomastigotes, favor parasite infection, thus increasing parasitemia ( Soprano et al., 2022 ).…”