1 2200 126 EPIGENETIC MODIFICATION OF FOXP3 IN PATIENTS WITH CHRONIC HIV INFECTION. OBJECTIVES: HIV-1 MODULATES HOST CELL EPIGENETIC MACHINERY TO CONTROL ITS OWN REPLICATION AND INDUCE IMMUNE SUPPRESSION. HIV-1 INFECTION LEADS TO ACTIVATION OF T REGULATORY CELL (T(REG)), BUT THE MECHANISM UNDERLYING THIS IMMUNE MODULATION IS UNCLEAR. T(REG) PLAYS A PROMINENT ROLE IN GUT-MUCOSAL IMMUNE TOLERANCE BY RESTRAINING EXCESSIVE EFFECTOR T-CELL RESPONSES, A MECHANISM THAT IS KNOWN TO BE DISTURBED IN CHRONIC HIV-1 INFECTION. DNA METHYLATION PLAYS A MAJOR ROLE IN T(REG) LINEAGE COMMITMENT AND IMMUNE HOMEOSTASIS, WHICH MAY BE REGULATED BY HIV. TO INVESTIGATE THE MECHANISMS OF ABERRANT METHYLATION OF THE T(REG) MARKER FOXP3 IN HIV-1 INFECTION, WE EVALUATED THE EXPRESSION PATTERN OF METHYLATION-RELATED ENZYMES AND ITS CORRELATION TO FOXP3 METHYLATION. METHODS: FOXP3 PROMOTER METHYLATION IN THE COLON MUCOSA AND PERIPHERAL BLOOD FROM HIV-INFECTED PATIENTS AND CONTROL SUBJECTS WAS MEASURED USING PYROSEQUENCING. GENE EXPRESSION PATTERN OF DNA METHYLATION ENZYMES IN THE COLON MUCOSA WAS INVESTIGATED BY MICROARRAY AND QUANTITATIVE REVERSE TRANSCRIPTASE-POLYMERASE CHAIN REACTION ANALYSIS IN THE SAME SUBJECTS. RESULTS: FOXP3 PROMOTER WAS SIGNIFICANTLY (P