Interleukin-6 CpG Methylation and Body Weight Correlate Differently in Type 2 Diabetes Patients Compared to Obese and Lean Controls.

Background/aims: Diabetes mellitus type 2 (DMT2) is accompanied by systemic low-grade inflammation with elevated levels of interleukin-6 (IL-6), which is encoded by a gene (IL-6) previously shown to be regulated by DNA methylation. We investigated seven CpG sites in IL-6 in individuals with DMT2, obese individuals and lean controls. Further, the DMT2 group received the glucagon-like peptide 1 agonist liraglutide.

Methods: Blood samples were taken at the beginning of the study and after 4 months. The DNA methylation was assessed using pyrosequencing.

Results: Methylation levels at the CpG sites -664, -628 and +13 at the first sampling time point (T1) and at -666 and -664 at the second sampling time point (T2) correlated negatively with initial body weight in the DMT2 group. We found positive correlations for the obese and the lean control group. In the obese group, CpG +27 methylation at T1 correlated with initial body weight (r = 0.685; p = 0.014). In the lean group, CpG -664 at T1 (r = 0.874; p = 0.005) and CpG -628 at T2 (r = 0.632; p = 0.050) correlated with initial body weight.

Conclusion: These findings are an informative basis for further studies to elucidate epigenetic mechanisms underlying DMT2. Additionally, our results might provide starting points for the development of biomarkers for prevention and therapy strategies.