Global methylation level in human adipose tissue is related to fat distribution

Aims: Epigenetic mechanisms may influence metabolic processes involved in human obesity. We examined the global methylation level in human subcutaneous vs. visceral adipose tissue and its relationship to obesity and related phenotypes.

Methods: We measured global methylation level using LUMA in paired samples of subcutaneous and visceral adipose tissue from 51 Caucasian individuals. Further, we analyzed the correlation of global DNA methylation in adipose tissue with parameters of obesity (BMI, WHR and fat area), glucose metabolism and insulin sensitivity.

Results: Global methylation levels were significantly higher in visceral adipose tissue (VAT) compared to subcutaneous adipose tissue (SAT). In lean individuals (n = 24), global methylation levels in SAT correlated positively with visceral fat area, the ratio of visceral and subcutaneous fat area, waist and WHR. Global methylation levels in SAT were further associated with fasting plasma glucose, HbA1c and glucose infusion rate (all adjusted P < 0.05).

Conclusion: Our data suggest that fat depot specific global methylation profiles may contribute to individual differences in fat distribution, glucose metabolism and insulin sensitivity. Further analyses of CpG island methylation in specific candidate genes involved in human obesity are currently ongoing.