Obesity and Bariatric Surgery Drive Epigenetic Variation of Spermatozoa in Humans

Obesity is a heritable disorder, with children of obese fathers at higher risk of developing obesity.  Environmental factors epigenetically influence somatic tissues, but the contribution of these factors to the establishment of epigenetic patterns in human gametes is unknown. Here, we hypothesized that weight loss remodels the epigenetic signature of spermatozoa in human obesity. Comprehensive profiling of the epigenome of sperm from lean and obese men showed similar histone positioning, but small non-coding RNA expression and DNA methylation patterns were markedly different. In a separate cohort of morbidly obese men, surgery-induced weight loss was associated with a dramatic remodeling of sperm DNA methylation, notably at genetic locations implicated in the central control of appetite. Our data provide evidence that the epigenome of human spermatozoa dynamically changes under environmental pressure, and offers  insight into how obesity may propagate metabolic dysfunction to the next generation. Overall design: Examination of the DNA methylation status, histone retention and sncRNA expression of the semen of 13 lean and 10 obese individuals; as well as the DNA methylation status of the semen of 6 obese men undergoing Roux-en-Y GBP surgery, at three time points: approximately 1 week before, 1 week after and 1 year after the surgery.