Modulation of DNMT-1 and HAT expression by oxidative stress in patients with Graves? autoimmunity.

MACRI DELBONO R.; COSTILLA M.; KLECHA A.; SABAN M.; CURRIA M.; DICUGNO M.; CREMASCHI, G.; BARREIRO ARCOS, M.L.

Leiden, Netherlands.

Conferencia; Leiden International Biomedical Student Conference (LIMSC); 2017

Leiden University Medical Center (LUMC)

Thyroid autoimmune diseases (AIDTs) are considered the most common autoimmune disorders. Environmental factors could be responsible for inducing epigenetic alterations that could trigger the pathology in individuals with genetic predisposition to the AIDTs. Graves? pathology is an autoimmune disease characterized by humoral hyper-reactivity against thyroid autoantigens leading to the state of hyperthyroidism in individuals. The aim of this work was to study the presence of epigenetic mechanisms in peripheral blood mononuclear cells (PBMC) of patients with Graves' disease, and analyze the involvement of oxidative stress in the induction of these mechanisms. For this purpose, the PBMC of patients with Graves? disease (n = 8 individuals) and healthy controls (n = 10 individuals) were purified from peripheral blood using Ficoll-Hypaque. Reactive oxygen species (ROS) levels were analyzed by flow cytometry, the expression of antioxidant enzymes, DNA methyltransferase-1 (DNMT-1) and histone acetyltransferase (HAT) was analyzed by real-time PCR and western blot and the histone modifications were analyzed by TAU-page.We have observed a significant increase of ROS in PBMC of patients with Graves? disease that was correlated with the increase in the activity and genomic expression of the Catalase and Glutatión Peroxidasa-1 enzymes. PBMC treated with an oxidative stress inducer (H2O2) showed a greater capacity to detoxification of peroxides in individuals with Graves' disease. This was accompanied by a lower level of apoptosis.We found a significant increase in the genomic and protein expression of DNMT-1 in PBMC of patients with Graves? disease. We also found a decrease in the genomic expression of HAT which was accompanied by an increase in the levels of histone hypoacetylation.Treatment with the antioxidant N-acetylcysteine (NAC) for 24 hours decreased the levels of ROS in PBMC of patients with Graves' disease. In addition, treatment with NAC decreased the genomic expression of DNMT-1 and increased mRNA levels of the HAT enzyme.These results allow us to infer that oxidative stress may induce epigenetic changes such as DNA methylation and histone hypoacetylation, which could affect gene transcription in lymphocyte cells involved in control of the immune response, contributing to autoimmunity in Graves' disease.