Complex mechanisms regulate T cell anergy during acute phase of Trypanosoma cruzi infection.

YAMILE ANA; ROJAS, JORGE; CERBAN F; CINTHIA STEMPIN

Congreso; REUNIÓN DE LA SOCIEDAD ARGENTINA DE INMUNOLOGÍA; 2016

We have previously shown that decreased T cell proliferation during acute phase of Trypanosoma cruzi infection is related to increase of inhibitory receptor and gene related to anergy in lymphocytes (GRAIL) expression, reduced IL2 production and expression of its regulator Otubain 1 (Otub-1). The aim of this study was to evaluate if GRAIL expression during infection is regulated by IL-2. BALB/c mice were infected i.p. with 500 trypomastigotes of Tulahuen strain and CD4+ cells were purified from spleen of uninfected or infected mice at 21 days post infection (d.p.i). First, we measured whether impaired proliferative response could be reversed by adding IL-2. CD4 T cells from control and 21 d.p.i animals were stimulated with anti-CD3/CD28 in the presence or absence of rmIL-2 for 3 days and then cell proliferation was assessed by CFSE. We found that CD4 T cells from control as well as 21 d.p.i animals had an increase in proliferation when treated with rmIL-2 together with the TCR stimulatory ligands. In addition, we also evaluated GRAIL and Otub-1 expression as well as mTOR activation in CD4 T cells with or without rmIL-2. In agreement with the increase in CD4 T cell proliferation, we found a slight rise in the phosphorylation of 4EBP1 (mTOR) and Otub-1 expression and a reduction in GRAIL expression. In addition we observed by FACS analysis that GRAIL was either expressed in naïve and in memory CD4+ T cell population. Furthermore, we tested if GRAIL expression could be induced directly and by different parasite strains. To perform this, CD4 T cells purified from BALB/c mice were incubated with Tulahuen or Y strain and 24h later GRAIL expression was assess by intracellular FACS staining. We have observed that both stains are able to induce GRAIL expression in vitro. These results may indicate that although GRAIL expression could be induced directly by different parasite strains its regulation may implicate a complex mechanism involving Otub-1, mTOR activation and IL-2.