Epigenetic regulation of IFN-g during Mycobacterium tuberculosis infection is mediated by Tle4, Blimp1 and Methylation at the -53 CpG site

ALVAREZ GI; HERNÁNDEZ DEL PINO RE; BARBERO AM; MUSELLA RM; PALMERO DJ; GARCÍA VE; PASQUINELLI V

CAPITAL FEDERAL

Congreso; IV Congreso de la Sociedad Latinoamericana de Inmunodeficiencias (LASID), LXIII Reunión de la Sociedad Argentina de Inmunología (SAI) y II Reunión FAIC (French-Argentinean Immunology Congress); 2015

LASID, SAI, FAIC.

IFN-g is a crucial cytokine during protective immunity against Mycobacterium tuberculosis (Mtb) infection. Elucidation of the mechanisms that regulates IFN-g will enhance our knowledge about Tuberculosis (TB) pathogenesis. IFNG expression could be regulated by several epigenetics mechanisms including histone modifications and DNA methylation. The transcriptional repressor complex Transducin-like enhancer of split 4 (Tle4) and B lymphocyte-induced maturation protein (Blimp1) binds to DNA and recruits histone deacetylases (HDACs). Blimp1 and TLE4 silence IFNG in anergic TH1 cells. Methylation of -53 CpG IFNG site is crucial during TH1 differentiation. Therefore, we evaluate Tle4/Blimp1 and -53 CpG methylation in the immune response to Mtb. Peripheral blood mononuclear cells (PBMCs) from Tuberculosis patients (PTB) and Healthy Donors (HD) were stimulated with sonicated Mtb. In some experiments, HDCACs inhibitors (HDACSi) Trichostatin A (TSA), Sodium butyrate (NaB) and Entinostat (MS275) were used. IFN-g expression (determined by Real Time PCR) was negatively correlated with TLE4/Blimp1 expression. In PTB the higher fold increase of IFN-g was observed at 24h (233.856 ± 93.14 (x±SEM)), while TLE4/Blimp1 showed the lowest values (1.034 ± 0.217/0.803 ± 0.125, respectively). Similar results were observed in HD at 48h. TSA and NaB inhibited IFN-g production (ELISA), but induce apoptosis even at low concentrations. MS275 increase IFN-g production at low concentration (Fold increase vs Mtb =426.82±162.49). -53 CpG methylation (bisulfite pyrosequencing) was associated with IFN-g production (pg/ml) in PTB DNA pools (66% x=2726.92 vs 74% x=403.70). Recruitment of HDACS trough TLE4/Blimp1 and -53 CpG methylation of IFNG could negatively regulate IFN-g expression during Mtb infection.