Relevance of sulfated oligosaccharides of cruzipain in the immunopathogenesis of Chagas disease

SOPRANO, LL; ACOSTA, DM; FERRERO, MR; GARCIA, GA; ESTEVA, MI; COUTO, AS; DUSCHAK, VG

Santa Fe, Prov. Sta. Fe, Argentina

Congreso; XXIII Reunión Científica Anual de la Sociedad Argentina de Protozoología; 2009

Sociedad Argentina de Protozoologia

Trypanosoma cruzi contains a major cysteine proteinase, cruzipain (Cz). This lysosomal enzyme bears an unusual C-terminal domain (C-T) that contains a number of post-translational modifications and is responsible for most antibodies in natural and experimental infections. UV-MALDI-TOF MS analysis, allowed us to identify the presence of sulfated high-mannose type oligosaccharides in the C-T as a new striking feature of this molecule. In order to evaluate the involvement of sulfated moieties in the crossreactivity between cardiac proteins and cruzipain, BALB/c mice were immunized with purified Cz and C-T prior and after desulfation treatment. The humoral immune response to sulfates on Cz or C-T was mainly IgG2b. This reactivity was abolished when desulfated antigens were used as immunogens showing that sulfates are absolutely required for eliciting IgG2b response to Cz. A significant reduction of C-T-specific delayed-type hypersensitivity reaction in C-T-immunized mice was observed when desulfated C-T was challenged, suggesting the involvement of sulfate groups in the generation of memory T-cell responses. Moreover, immunization with C-T elicited ultrastructural abnormalities in heart tissue. Surprisingly, pathological alterations were not observed in hearts from sulfate depleted-C-T-immunized mice and a lower labeling was observed by immunoelectron microscopy using myosin-adsorbed specific policlonal anti-Cz serum. Furthermore, when BALB/c mice immunized with C-T and desulfated C-T were challenged with trypomastigotes, immunepathological enhanced responses were observed in cardiac and muscle mice tissues previously immunized with C-T. Our results highlight the relevance of sulfated groups as main components of this molecule and suggest it plays a role in the immunopatogenesis of Chagas disease. Ongoing assays using specific anti-sulfate antibodies will help to elucidate the involvement of sulfates in the antigenicity and crossreactivity of this unique glycoprotein