DNA methylation of the TNF-α promoter region in peripheral blood monocytes and the cortex of human Alzheimer's disease patients.

ABSTRACT

BACKGROUND: The cytokine tumor necrosis factor-alpha (TNF-α) is elevated in the blood of Alzheimer's disease (AD) patients. Epigenetic DNA modifications of the TNF-α promoter may account for the observed upregulation. METHODS: We analyzed blood samples of 50 AD patients and 55 controls plus 4 AD and 4 control cortex samples using bisulfite sequencing PCR. RESULTS: A significant hypomethylation of the TNF-α promoter was found in AD patients' brains but not in their blood. Cortical TNF-α promoter DNA was higher methylated than blood-derived DNA, both in AD patients and controls. CONCLUSION: In AD patients, epigenetic mechanisms of TNF-α gene regulation, like aberrant DNA methylation, are not relevant in blood.