Introduction: In Central Europe, vitamin D deficiency is common, and a very pronounced deficiency of this vitamin is observed in obese individuals. We hypothesized that the decreased serum concentration of vitamin D might be in part due to the changed metabolism of this vitamin in adipose tissues.
Methods: We assessed the expression of vitamin D 25-hydroxylase genes CYP2J2 and CYP2R1 in adipose tissues of obese and slim patients using RT-PCR. Subcutaneous (SAT) and visceral (VAT) adipose tissues were obtained from obese subjects (n=62, BMI 39-68 kg/m2) during bariatric surgery (RYGB or VBG) and from non-obese controls (n=30, BMI 20-26 kg/m2) undergoing scheduled surgical procedures. Serum concentrations of 25OH-vitamin D were measured with the Diagnostics Vitamin D Total Assay (Roche) and IDS manual immunoassay. The results of both tests were correlated with each other.
Results: The mean serum concentration of 25OH-vitamin D was low and similar in obese and slim patients (15.23 ng/ml vs 18.97 ng/ml respectively, P>0.05). The mean expression of CYP2J2 was similar in VAT (107±20.01 arbitrary units (AU) vs 110±5.63 AU, P>0.05) and in SAT (112.80±8.66 AU vs 107.80±4.64 AU, P>0.05) of obese vs slim subjects. Similarly, the mean expression of CYP2R1 in VAT (120.19±12.43 AU vs 110.05±5.62 AU, P>0.05) and in SAT (119.60±12.60 vs 110.44±5.88 AU, P>0.05) was similar in obese vs slim subjects. A negative correlation (R=−0.30) between the expression of CYP2R1 in SAT of obese individuals and serum concentration of 25OH-vitamin D was found, while it was positive (R=0.20) in SAT of slim patients.
Conclusion: The expression of CYP2R1 is similar in VAT and SAT of obese and slim patients. Nevertheless, an opposite relationship between serum concentration of 25OH-vitamin D and the expression of this gene in SAT of obese and slim patients has been noted.