Potential Epigenetic Biomarkers of Obesity Related Insulin Resistance in Human Whole Blood

Obesity is a critical health concern, and identifying new biomarkers has become essential for better understanding the progression to disease such as type 2 diabetes. DNA methylation has become a useful epigenetic biomarker in part due to its susceptibility to disease influence. Detecting methylation changes in blood is important as it is an easily accessible, compared to the insulin responsive tissue skeletal muscle. The aim of our study was to identify methylation changes in whole blood that were strongly associated with obesity associated insulin resistance. Whole blood was obtained from lean (n=10; BMI= 23.6±0.7 kg/m2) and obese (n=10; BMI= 34.4±1.3 kg/m2) participants in combination with euglycemic hyperinsulinemic clamps to assess insulin sensitivity. We performed the next generation technique, reduced representation bisulfite sequencing (RRBS) on isolated genomic DNA. There were 49 significantly altered differentially methylated cytosines (DMCs; q<0.05). Of these, solute carrier family 19 member 1 (SLC19A1) was also identified using a differentially methylated region approach. The sites for this gene were significantly correlated (P<0.05) with body mass index, body fat percent, and the clamp Rd. Moreover, the decrease in SLC19A1 methylation was similar to the change previously found in skeletal muscle. Pyrosequencing confirmed the changes in methylation at Chr.21:46,957,915 in both tissues. These results demonstrate that the methylation status of SLC19A1 provides a new potential epigenetic biomarker for obesity related insulin resistance. Whole blood were obtained in PAXgene tubes from lean (n=10) and obese (n=10) participants in combination with euglycemic hyperinsulinemic clamps to assess insulin sensitivity. We performed reduced representation bisulfite sequencing next generation methylation analysis on DNA isolated from whole blood.