Characterization of Methylation-Sensitive CCGG Sites in the Promoters of Inflammatory Cytokine Genes in Hypertensive Patients from Kano State

Hypertension is reaching epidemic proportions in urban Nigerian populations, and chronic low-grade vascular inflammation is recognized as a key pathogenic mechanism. DNA methylation at CpG sites within promoters of inflammatory cytokine genes may regulate their expression and contribute to hypertension-associated endothelial dysfunction. This study characterized methylation-sensitive CCGG sites in the promoters of TNF-alpha, IL-6, and IL-1beta genes in hypertensive patients compared with normotensive controls attending Aminu Kano Teaching Hospital (AKTH), Kano State, Northwest Nigeria. Peripheral blood samples were collected from 60 newly diagnosed hypertensive patients and 60 age-sex matched controls. Genomic DNA was extracted and digested with methylation-sensitive HpaII and methylation-insensitive MspI restriction enzymes targeting CCGG sites. PCR amplification of promoter regions flanking CCGG sites provided semiquantitative methylation estimates. Bisulfite pyrosequencing was performed on selected CpG sites for quantitative validation. TNF-alpha promoter CCGG site hypomethylation was detected in 68.3% of hypertensive patients compared with 23.3% of controls (p less than 0.001). IL-6 promoter hypomethylation showed a similar trend in 55% of hypertensive subjects. Lower methylation levels correlated significantly with higher serum TNF-alpha and IL-6 concentrations measured by ELISA. These epigenetic findings suggest that inflammatory cytokine gene promoter hypomethylation is associated with hypertension pathogenesis in the Kano State population and may represent an epigenetic biomarker target. Keywords: DNA methylation, cytokine gene promoters, hypertension, epigenetics, Kano State.