Cruzipain: Immunomodulation and immunoprotection

FRANK F.M., CAZORLA S.I, DELETTIERES D, MALCHIODI E.L

Mendoza, Argentina

Conferencia; VII Congreso Argentino de Protozoologia y Enfermedades Parasitarias; 2005

Cruzipain (Cz) is a potential target for raising a protective immune response against Chagas disease. We analyzed the ability of CpG+Cz to induce immunoprotection against a lethal challenge. Mice showed a Th1 response characterised by secretion of IFN-gama, IL2 and specific antibody, mostly IgG2a. Trypomastigote challenge displayed low parasitemia and 100% survival to acute infection. We analyzed hearth and skeletal muscle of immunized mice founding citoplasmatic hyalinization, architecture modification and small inflammatory foci only in quadriceps of those that elicited a Th2 response (Alum+Cz), demonstrating the importance of the adjuvant employed. CpG may trigger macrophages (Mo) to release TNFá resulting in apoptosis of liver cells. We examined the capacity of Cz in modulating this toxic effect. J774 Mo stimulated with CpG elicited 3 folds more TNFá than cells cultured with CpG+Cz. CpG immunized mice livers presented significantly more apoptotic bodies than control, while no difference was observed in CpG+Cz immunized mice. Micro and macroabscess, perivascular unicellular necrosis and small chronic inflammatory infiltrates were observed in CpG livers, while only focal Kuppfer cell hyperplasia were found in CpG+Cz immunized mice. These suggest that Cz is able to revert the hepatotoxic effect elicited by CpG. To a better understanding of the immunoprotection, we analyzed the effect of Cz on dendritic cell (DC). Cz reduced endocytosis and MHCII expression, improved the expression of CD11b and secretion of IL10 and TNFa. When the ability of DC to stimulate allogeneic T cell was analysed 2.7 fold decrease in MLR was observed in DC pulsed with Cz, and effect that was reverted by stimulation of CpG. These results provide the basis for the design of a anti-T. cruzi vaccine which may be used to protect or alleviate the pathogenic responses of Chagas disease.