The association between body mass index elevation and differentiation in vitamin D receptor gene expression, genetic polymorphism, and oxidative stress in adult Egyptian individuals

Abstract

Vitamin D plays a central role in maintaining calcium, phosphorus, and bone homeostasis in close interaction with the parathyroid hormone. Obesity is a significant health problem worldwide, particularly in developed nations. The current study was carried out to investigate the possible relationship between body mass index (BMI) elevation and differentiation in 25-hydroxyvitamin D (VD), vitamin D receptor (VDR) gene expression, and genetic polymorphism besides oxidative stress in adult Egyptian individuals. This was done to explore the mechanisms underlying the suggested role of the VD/VDR complex in the pathogenesis of obesity. A total of 70 subjects (30 obese, 25 overweight, and 15 normal, age: 20–50 years, without other chronic diseases) were selected. The study focused on the determination of VD, VDR gene polymorphism, VDR gene expression, alkaline phosphatase, calcium, phosphorus, glucose, lipid profile, oxidative stress including, oxidant (malondialdehyde), and anti-oxidants (reduced glutathione and superoxide dismutase). The results showed that elevation in BMI led to the percentage of the Ff 'allele' becoming predominant, while the percentage of the FF 'allele' was in the normal BMI range. Also, BMI elevation caused significant reductions in VD and VDR expression, with significant elevations in alkaline phosphatase and the levels of calcium and phosphate in serum. Also, oxidative stress increases with increasing BMI. Elevation in BMI causes a reduction in VD concentration and VDR gene expression levels. Also, the percentage of heterozygous mutant genotype Ff 'allele' is predominantly in the obese human, in contrast to normal subjects, where the percentage of homozygous wild genotype FF 'allele' is predominant. In general, the genetic expression and polymorphism of VD and VDR can be used as a genetic marker for predisposition, diagnosis, prognosis, and progression of obesity.