Cruzipain: Immunomodulation and immunoprotection

FRANK FM; CAZORLA SI; DELETTIERES D; MALCHIODI EL

Mendoza

Congreso; VII Congreso Argentino de Protozoología y Enfermedades Parasitarias; 2005

Cruzipain (Cz) is a potential target to raise a protective immune response against Chagas’ disease. We analyzed the ability of Cz+CpG to induce immunoprotection against a lethal challenge. Immunized mice showed a Th1 response with secretion of IFNã, IL2 and specific Ab, mostly IgG2a. Trypomastigote challenge displayed low parasitemia and 100% survival to acute infection. We analyzed hearth and skeletal muscle of immunized mice founding cytoplasmatic hyalinization, architecture modification and small inflammatory foci only in quadriceps of mice immunized with Cz+Alum (Th2 response), demonstrating the importance of the adjuvant. 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 Cz+CpG. Livers from mice immunized only with CpG presented significantly more apoptotic bodies than control, while no difference was observed in Cz+CpG immunized mice. Micro and macroabscess, perivascular unicellular necrosis and small chronic inflammatory infiltrates were observed in CpG livers, while only focal Kuppfer cell hyperplasia was found in Cz+CpG immunized mice. These results suggest that Cz would be able to revert the hepatotoxic effect of CpG. To better understand the immunoprotection elicited by Cz, we tested its effect on dendritic cell (DC). Cz reduced endocytosis and MHCII expression, increased expression of CD11b and secretion of IL10 and TNFa. When the ability of DC to stimulate allogeneic T-cell was analyzed, a 2.7 fold decrease in mixed leucocyte reaction was observed with DC pulsed with Cz. This effect was reverted by stimulation with 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 consequences of Chagas’ disease.