Reduction of parasite levels in blood improves pregnancy outcome during experimental Trypanosoma cruzi infection

Infection with a myotropic Trypanosoma cruzi clone induces maternal fertility failure. In the current work, we evaluated whether reduction of maternal parasitaemia before mating has beneficial effects on pregnancy outcome. Female mice were subjected to benznidazole (Bz) treatment after infection. On day 30 of therapy, mating was assessed and pregnancy outcome was determined on day 14 of gestation. Fetal resorptions diminished in T. cruzi-infected Bz-treated mice compared with T. cruzi-infected untreated mice. This was in agreement with the reduction in the blood/solid tissue parasite load and with the percentage of necrotic foci in placental samples from T. cruzi-infected Bz-treated females. To study eventual changes in the immune homeostasis of T. cruzi-infected Bz-treated mice, activation of the immune system was evaluated at the end of Bz therapy and before mating. We found specific IgG1 reduction resulting in a predominance of specific IgG2a, reduced numbers of CD69+ CD4+ cells and diminished frequency and numbers of CD44+ T cells. Concanavalin A-stimulated splenocytes from T. cruzi-infected Bz-treated mice produced higher amounts of IFN-c than T. cruzi-infected untreated mice. These results indicate that reduction of maternal parasite load improves pregnancy outcome. These findings correlate with a favourable modulation of the immune response.