Role of TNF in sickness behavior and allodynia during the acute phase of Chagas' disease.

Chagas disease, caused by the intracellular protozoan Trypanosoma cruzi, is associated with inflammation, discomfort and pain during the acute phase. The influence of TNF-α (tumor necrosis factor) in this disease outcome is controversial. In this way, the aim of this work was to determine the role of the TNF-α blocker etanercept in the pain, discomfort, and survival during the Chagas' acute phase of mice experimentally infected with a wild virulent strain of T. cruzi. The infection with this wild strain was responsible for a severe visceral inflammation and said parasite showed a tropism in peritoneal fluid cells. Etanercept was able to restore spontaneous vertical and horizontal activities during the second week after infection and to abolish mechanical allodynia during the first week after infection. Finally, etanercept delayed the mortality without any effect on the parasitemia rates. This is the first report that correlates sickness behavior and allodynia with TNF-α and suggests that this cytokine may play an important role in the physiopathology of the acute phase.