Epigenetic profiles in blood and adipose tissue: identifying strong correlations in morbidly obese and non-obese patients.

Epigenetic alterations play a pivotal role in conditions influenced by environmental factors such as overweight and obesity. Many of these changes are tissue-specific, which entails a problem in its study since obtaining human tissue is a complex and invasive practice. While blood is widely used as a surrogate biomarker, it cannot directly extrapolate the evidence found in blood to tissue. Moreover, the intricacies of metabolic diseases add a new layer of complexity, as obesity leads to significant alterations in adipose tissue, potentially causing associated pathologies that can disrupt existing correlations seen in healthy individuals. Here, our objective was to determine which epigenetic markers exhibit correlations between blood and adipose tissue, regardless of the metabolic status. We collected paired blood and adipose tissue samples from 64 patients with morbidity obesity and non-obese and employed the MethylationEPIC 850 K array for analysis. We found that only a small fraction, specifically 4.3% (corresponding to 34,825 CpG sites), of the sites showed statistically significant correlations (R ≥ 0.6) between blood and adipose tissue. Within this subset, 5327 CpG sites exhibited a strong correlation (R ≥ 0.8) between blood and adipose tissue. Our findings suggest that the majority of epigenetic markers in peripheral blood do not reliably reflect changes occurring in visceral adipose tissues. However, it is important to note that there exists a distinct set of epigenetic markers that can indeed mirror changes in adipose tissue within blood samples. KEY MESSAGES: More than 8% of methylation sites exhibit similarity between blood and adipose tissues, regardless of BMI The correlation percentage between blood and adipose tissue is strongly influenced by gender The principal genes implicated in this correlation are related to metabolism or the immunological system.