Epigenetic Landscape in Blood Leukocytes Following Ketosis and Weight Loss Induced by a Very Low Calorie Ketogenic Diet (VLCKD) in Patients With Obesity

Abstract

[Abstract] Background:The molecular mechanisms underlying the potential health benefits of a ketogenic diet areunknown and could be mediated by epigenetic mechanisms.Objective:To identify the changes in the obesity-related methylome that are mediated by the inducedweight loss or are dependent on ketosis in subjects with obesity underwent a very-low calorie ketogenicdiet (VLCKD).Methods:Twenty-one patients with obesity (n¼12 women, 47.9±1.02 yr, 33.0±0.2 kg/m2) after 6months on a VLCKD and 12 normal weight volunteers (n¼6 women, 50.3±6.2 yrs, 22.7±1.5 kg/m2)were studied. Data from the Infinium MethylationEPIC BeadChip methylomes of blood leukocytes wereobtained at time points of ketotic phases (basal, maximum ketosis, and out of ketosis) during VLCKD(n¼10) and at baseline in volunteers (n¼12). Results were further validated by pyrosequencing inrepresentative cohort of patients on a VLCKD (n¼18) and correlated with gene expression.Results:After weight reduction by VLCKD, differences were found at 988 CpG sites (786 unique genes).The VLCKD altered methylation levels in patients with obesity had high resemblance with those fromnormal weight volunteers and was concomitant with a downregulation of DNA methyltransferases(DNMT)1, 3a and 3b. Most of the encoded genes were involved in metabolic processes, protein meta-bolism, and muscle, organ, and skeletal system development. Novel genes representing the top scoringassociated events were identified, includingZNF331,FGFRL1(VLCKD-induced weight loss) andCBFA2T3,C3orf38,JSRP1, andLRFN4(VLCKD-induced ketosis). Interestingly,ZNF331andFGFRL1were validated inan independent cohort and inversely correlated with gene expression.Conclusions:The beneficial effects of VLCKD therapy on obesity involve a methylome more suggestive ofnormal weight that could be mainly mediated by the VLCKD-induced ketosis rather than weight loss.