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

GUADALUPE INES ALVAREZ; HERNÁNDEZ DEL PINO, RODRIGO E; BARBERO ANGELA; , MUSELLA R.M; PALMERO DJ; GARCIA VE; PASQUINELI, V

Congreso; 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

Abstract Text: 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 aboutTuberculosis (TB) pathogenesis. IFNG expression could be regulated by several epigeneticsmechanisms including histone modifications and DNA methylation. The transcriptional repressorcomplex 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 inanergic TH1 cells. Methylation of -53 CpG IFNG site is crucial during TH1 differentiation. Therefore, weevaluate Tle4/Blimp1 and -53 CpG methylation in the immune response to Mtb. Peripheral bloodmononuclear cells (PBMCs) from Tuberculosis patients (PTB) and Healthy Donors (HD) were stimulatedwith sonicated Mtb. In some experiments, HDCACs inhibitors (HDACSi) Trichostatin A (TSA), Sodiumbutyrate (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 wasobserved 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). -53CpG methylation (bisulfite pyrosequencing) was associated with IFN-g production (pg/ml) in PTB DNApools (66% x=2726.92 vs 74% x=403.70). Recruitment of HDACS trough TLE4/Blimp1 and -53 CpGmethylation of IFNG could negatively regulate IFN-g expression during Mtb infection.