Role of mTOR pathway in macrophage polarization and Trypanosoma cruzi infection

ROJAS M, JD; STEMPIN, CC; CERBÁN, FM

Mar del PLata

Congreso; LIX Reunión Científica Anual de la Sociedad Argentina de Investigación Clínica, LXII Reunión Científica Anual de la Sociedad Argentina de Inmunología; 2014

Previously we have shown that T. cruzi modulates macrophage (Mo) polarization to M2 profile through the induction of arginase, generation of anti-inflammatory cytokines and up-regulation of co-inhibitory molecules such as PD-Ls. Besides, induction of M1 Mo is important to control T. cruzi intracellular replication. Furthermore, we have also demonstrated that mTOR pathway is activated by T. cruzi infection and its inhibition using Rapamicyn (Rap) decreased parasite survival, modified IL-10/IL-12 balance, reduced arginase activity and expression in T. cruzi infected Mo. Therefore, the aim of this work was to extend the study of the role of mTOR in Mo polarization and T. cruzi replication. To do that, we evaluated the kinetic of mTOR activation through 4EBP-1 and p70S6K phosphorylation in vitro as well as in vivo. Bone marrow derived Mo (BMDM) infected in vitro showed 4EBP-1 and p70S6K phosphorylation after 6, 24, 48 and 72 hs post- infection, with a peak at 24 hs. In addition in adherent spleen cells and peritoneal Mo from T. cruzi infected mice 4EBP-1 phosphorylation was detected at 7, 14, 25 and 28 days post infection, with a peak at day 25. Next, BMDM were pre-treated with Rap and then incubated with T. cruzi trypomastigotes or in polarizing conditions with LPS + IFN-g (M1 Mo) or IL-4 (M2 Mo). Then, we examined the effect of mTOR inhibition in iNOS/arginase balance. Surprisingly, as we have previously observed with the enzyme arginase, we have found that pre-treatment with Rap also decreased iNOS activity measured by nitrite content and down-regulated its protein expression in T. cruzi infected Mo. mTOR inhibition was confirmed by reduction in mTOR, 4EBP-1 and p70S6K phosphorylation at 48 hs of infection. Therefore, it remains to elucidate the mechanism/s of parasite inhibition in Rap-treated Mo. Taken together these results suggest that the modulation mTOR pathway may be important during the course of T. cruzi infection.