Toll like receptor (TLR) family is responsible for initiating acute immune response against pathogens by induction of proinflammatory cytokines.
Our aim was to analyze the parasitemia-survival and the kinetic of TLR2, TLR4, TNFa, IL-6, IL-12, IL-10 and TGFb gene expression in splenocytes from infected BALB/c and C57BL/6. Mice (n=10 each) were ip infected with 5x103 trypomastigotes (Tulahuen). The histological study of heart, liver and spleen was also performed.
Parasitemia was higher in BALB/c than in C57BL6 (4x106 versus 1x106parasites/ml at the peak), and mortality reached 40% and 85% respectively until 24 days post infection (dpi).
TLR2 messenger showed an up-regulation at 24 dpi in C57BL/6 whereas TLR4-mRNA displayed a down-regulation in both strains compared to uninfected mice. IL-12, IL-6 and TNFa mRNA showed the major changes, IL-12 increased in C57BL/6 and decreased in BALB/c. IL6 mRNA was up-regulated until 21 dpi, while TNFa messenger was up-regulated over the infection progress only in C57BL/6. On day 14, high levels of TNFa were also found in sera from C57BL/6 and BALB/c.
In myocardium amastigote nests were observed earlier in BALB/c. Inflammatory infiltrates in heart and liver were found more frequently in C57BL/6.
In acute T. cruzi infection, C57BL/6 showed a TLR2 mRNA up-regulation associated with an inflammatory cytokine profile and a higher number of cellular infiltrates.
