title: DNMT1 modulation in chronic hepatitis B patients and hypothetic influence on mitochondrial DNA methylation status during long-term nucleo(t)side analogs therapy.
abstract: Inhibition of viral replication is the most important goal in patients with Hepatitis B virus chronic infection (CHB). Currently, five oral nucleo(t)side analogs (NAs), including Lamivudine, Adefovir, Telbivudine, Entecavir, and Tenofovir, have been approved for treatment. The widespread use of NAs has also been linked with a progressive growth of unlikely anomaly attributable to mitochondrial dysfunctions, not previously recognized. Here, we explore the hypothesis that NAs may cause persistent epigenetic changes during prolonged NAs therapy in CHB patients. We obtained peripheral blood mononuclear cells (PBMC) from whole blood samples of consecutive patients with chronic HBV infection, 18 receiving NAs and 20 untreated patients. All patients were Caucasian and Italians. Epigenetic analysis was performed by Bisulphite sequencing PCR to search the existence of methylated cytosine residues in the Light (L)-strands of mitochondrial DNA control region (D-loop). Gene expression analysis of DNA methyltransferases 1 was performed by a quantitative relative Real-Time Polymerase Chain Reaction (PCR). DNMT1 expression was significantly (P < 000001) higher in NA treated patients (4.09, IQR 3.52-5.15) when compared with HBV naives (0.61, IQR 0.34-0.82). Besides, DNMT1 expression was significantly correlated with NA therapy duration (Spearman Rho = 0.67; P < 0.05). Furthermore, NA therapy duration was the only significant predictor of DNMT1 expression at multivariate analysis (Beta = 0.95, P < 0.0000001). Bisulphite PCR sequencing showed that methylation of cytosine residues occurred in a higher percentage in patients treated with NAs in comparison with untreated patients and healthy controls. Our data showed a DNMT1 overexpression significantly correlated to NA therapy duration and an higher regional mtDNA hypermethylation. This might suggest an epigenetic alteration that could be involved in one of the possible mechanisms of mitochondrial gene regulation during NAs therapy.
authors.affiliation: Unit of Infectious Diseases, Department of Clinical and Experimental Medicine, University of Sassari, Sassari, Italy.
authors.forename: Giordano
authors.initials: G
authors.lastname: Madeddu
authors.affiliation: Unit of Infectious Diseases, Department of Clinical and Experimental Medicine, University of Sassari, Sassari, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Ortu
authors.affiliation: Unit of Internal Medicine, Department of Clinical and Experimental Medicine, University Hospital, Sassari, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Garrucciu
authors.affiliation: Unit of Infectious Diseases, Department of Clinical and Experimental Medicine, University of Sassari, Sassari, Italy.
authors.forename: Ivana
authors.initials: I
authors.lastname: Maida
authors.affiliation: Unit of Infectious Diseases, Department of Clinical and Experimental Medicine, University of Sassari, Sassari, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Melis
authors.affiliation: Unit of Infectious Diseases, Department of Clinical and Experimental Medicine, University of Sassari, Sassari, Italy.
authors.forename: Alberto Augusto
authors.initials: AA
authors.lastname: Muredda
authors.affiliation: Unit of Infectious Diseases, Department of Clinical and Experimental Medicine, University of Sassari, Sassari, Italy.
authors.forename: Maria Stella
authors.initials: MS
authors.lastname: Mura
authors.affiliation: Unit of Infectious Diseases, Department of Clinical and Experimental Medicine, University of Sassari, Sassari, Italy.
authors.forename: Sergio
authors.initials: S
authors.lastname: Babudieri
mesh_terms: D000225:Adenine / Q000009:adverse effects / Q000031:analogs & derivatives; D000368:Aged; D000998:Antiviral Agents / Q000009:adverse effects*; D003430:Cross-Sectional Studies; D003596:Cytosine / Q000737:chemistry; D000076123:DNA (Cytosine-5-)-Methyltransferase 1 / Q000235:genetics*; D019175:DNA Methylation; D004272:DNA, Mitochondrial / Q000737:chemistry*; D005260:Female; D006147:Guanine / Q000009:adverse effects / Q000031:analogs & derivatives; D019694:Hepatitis B, Chronic / Q000097:blood / Q000188:drug therapy* / Q000821:virology; D006801:Humans; D019259:Lamivudine / Q000009:adverse effects; D007963:Leukocytes, Mononuclear; D008297:Male; D008875:Middle Aged; D009705:Nucleosides / Q000737:chemistry / Q000627:therapeutic use*; D063065:Organophosphonates / Q000009:adverse effects; D060888:Real-Time Polymerase Chain Reaction; D018894:Reverse Transcriptase Inhibitors / Q000009:adverse effects*; D000077712:Telbivudine; D013936:Thymidine / Q000009:adverse effects / Q000031:analogs & derivatives
chemical_list: D000998:Antiviral Agents; D004272:DNA, Mitochondrial; D009705:Nucleosides; D063065:Organophosphonates; D018894:Reverse Transcriptase Inhibitors; D000077712:Telbivudine; D019259:Lamivudine; C413685:entecavir; D006147:Guanine; C053001:adefovir; D003596:Cytosine; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; C000619380:DNMT1 protein, human; D000225:Adenine; D013936:Thymidine
keywords: antiviral therapy; epigenetic; methylation; mitochondrial DNA; nucleo(t)side analogs