Trypanosoma cruzi infection in mice impact on thymic and peripheral CD4+CD25+FoxP3+ regulatory T cells.

RODRIGO FERNÁNDEZ BUSSY, SILVINA VILLAR, ROMINA MANARIN, GAELLE MARTIN, FLORENCIA GONZÁLEZ, SILVIA REVELLI, ELIANE PIAGGIO, JOSÉ COHEN, OSCAR BOTTASSO, ANA ROSA PÉREZ.

Congreso; X Latin-american congress of immunology 2012; 2012

CD4+CD25+FoxP3+ regulatory T cells (Treg) develop in the thymus and are also induced in periphery. T. cruzi infection cause severe thymus atrophy, possibly affecting the Treg supply and the subsequent resolution of the disease. Therefore, we studied the characteristics of Treg in mouse strains with different susceptibility to acute infection (Survival rate in C57BL/6 (B6) =0%, BALB/c (Bc)=30-40%). Baseline ratio of thymic Treg was larger in Bc than in B6 (p<0.05). After infection their absolute number declined, but their ratio increased more in Bc (p<0.05). FoxP3 protein and mRNA expression increased in Bc compared to B6 (p<0.05). The infection increases the absolute number of Treg in periphery. However, the ratio of blood circulating Treg declined progressively, showing higher values in Bc compared to B6, while in spleen and lymph nodes reached similar levels. Depletion of CD25+ cells previous the infection did not prevent the expansion of Treg nor modified parasitemia or mortality in any strain. Treatment tending to increase Treg using IL-2 during the first days of infection failed to boost their expansion, but attenuated parasitemia without changes in the survival rate. To conclude, the higher basal levels of Treg and the higher blood ratio observed during the infection in Bc compared to B6, might explain the better resolution of the infection by this strain.