No effect of weight loss on LINE-1 methylation levels in peripheral blood leukocytes from postmenopausal overweight women.

OBJECTIVES:Obesity and weight-loss are associated with methylation patterns in specific genes, but their effect on Long Interspersed Nuclear Elements (LINE-1) methylation, a measure of global methylation is largely unknown. METHODS:Three hundred overweight/obese post-menopausal women (50-75 years) were part of a completed, 1-year randomized controlled trial, comparing independent and combined effects of a reduced-calorie weight-loss diet, and exercise program, versus control. DNA was extracted from peripheral blood leukocytes collected at baseline and 12-months, and LINE-1 methylation analyzed by pyrosequencing. Mean changes between groups using generalized estimating equations and examined effects of weight-loss on LINE-1 methylation using stratified analyses (gained weight/no weight-loss [N = 84]; <5% [N = 45]; 5%-10% [N = 45]; >10% of baseline weight-loss [N = 126]) within each arm, adjusted by blood cell counts were compared. Associations between LINE-1 methylation and previously measured biomarkers, and anthropometrics were also examined. RESULTS:No significant difference in LINE-1 methylation levels was detected in any intervention group versus controls. The magnitude of weight-loss was not associated with LINE-1 methylation at 12-months. There were no associations between baseline characteristics of participants, or previously measured biomarkers, and LINE-1 methylation. CONCLUSIONS:Our results suggest that lifestyle changes sufficient to significantly reduce weight over 12-months may not change LINE-1 DNA methylation levels.