Hypomethylation of interleukin-6 ( IL-6 ) gene increases the risk of essential hypertension: a matched case–control study

Essential hypertension (eh) is a chronic disease with clear epigenetic component. inflammation and endothelial dysfunction have a great role in the development of persistent blood pressure elevation. the aim of this study was to explore an association between eh and dna methylation in pro-inflammation cytokine gene interleukin-6 (il-6) during the inflammatory process. we performed methylation analysis of peripheral blood dna using bisulphite pyrosequencing technology between 96 eh patients and 96 age- and gender-matched healthy controls. the present results showed that three cytosine–phosphate–guanine (cpg) sites of il-6 promoter cpg island had different lower methylation in eh group compared with controls, but only cpg2 (58.43±7.53 versus 62.34±9.65, p=0.004) and cpg3 (51.52±6.18 versus 57.45±8.29, p<0.001) had statistical difference. logistic regression analysis found cpg3 hypomethylation was a risk factor of eh (odds ratio=1.111, adjusted p=0.004). in addition, we found hypermethylation of cpg1 (64.84±7.06 versus 61.84±8.61) and cpg2 (62.04±7.40 versus 59.30±9.57) in male compared with female. in male, we found hypomethylation of cpg2 (60.41±7.74 versus 64.28±6.36) and cpg3 (53.70±8.62 versus 57.78±7.87) of smoker versus non-smoker and hypomethylation of cpg2 (60.89±7.32 versus 64.70±7.03) and cpg3 (53.23±7.99 versus 60.48±7.58) of drinker versus non-drinker. furthermore, the cpg2 and cpg3 had a negative correlation with systolic blood pressure and diastolic blood pressure (p<0.05). receiver operating characteristic curve analysis showed that cpg2 (area under curve: 0.638, p=0.001) and cpg3 (area under curve: 0.704, p<0.001) had a diagnostic value to predict the risk of eh. in summary, our study revealed hypomethylation of il-6 was correlated with the risk of eh in the population assessed and we found the differences of il-6 promoter methylation in gender, smoking and drinking.