The expression and methylation status of vitamin D receptor gene in Behcet's disease

Vitamin D has important roles as a natural immune modulator
via regulating the expression of genes which have been implicated in the
pathophysiology of autoimmune diseases. Vitamin D function and its deficiency
have been linked to a wide range of metabolic disorders including disorders of
calcium metabolism, malignant, cardiovascular, infectious, neuromuscular, and
inflammatory diseases. Environmental factors, genetic factors, and epigenetic
changes contribute to Behcet's disease (BD) development. The aim of our study
was to analyze the expression level and methylation status of the vitamin D
receptor (VDR) gene promoter in the peripheral blood mononuclear cells
(PBMCs) of patients with BD.
Methods: In a case‐control study, 48 Iranian Azeri patients with BD and 60
age‐, sex‐ and ethnically‐matched healthy controls were included. Venous blood
samples were collected and PBMCs were isolated by Ficoll protocol. The DNA
and RNA were subsequently extracted. Promoter methylation levels were
evaluated by MeDIP‐quantitative polymerase chain reaction (qPCR). The
expression of VDR was evaluated by real‐time PCR.
Results: The results of quantitative real‐time PCR analysis showed that the
level of VDR expression in patients with BD was significantly lower than the
control group (P = .013). There was no significant difference in the level of DNA
methylation in the BD and control groups (P > .05). As the results show, the
expression level of VDR gene was significantly different between female and
male in the patient group (P = .001). VDR gene expression was significantly
higher in subjects with phlebitis. No correlation was observed between VDR
gene expression rate and BD activity.
Conclusion: VDR gene expression decreased in patients with BD. However,
there is no suggestion evidence that the expression level of VDR is regulated by
a unique DNA methylation mechanism. No correlation exists between VDR
gene expression and BD activity.