Vitamin D and Vitamin D Receptor in Scleroderma Subtypes

Abstract

Vitamin D Receptor (VDR) is a member of the nuclear hormone receptor family. 1,25(OH)2D, a form of metabolically active vitamin D3 form, is the ligand of VDR. When VDR and 1,25(OH)2D are connected, many genes start to molecular interaction reactions that will modulate the transcription. VDR has been shown to be a negative regulator of the transforming growth factor beta-1 / Smad (TGF-β1 / Smad) signalling pathway. TGF-β1 / Smad signalling is important in the pathogenesis of scleroderma (SSc). Vitamin D has pleiotropic effects including immunomodulatory and antifibrotic properties in scleroderma pathogenesis. The aim of this study was to investigate the expression of VDR and the levels of vitamin D in scleroderma subtypes and study the possible correlation between the two parameters. 28 SSc patients and 30 healthy controls were included in the study and they were classified according to the 2013 ACR / EULAR criteria and Rodnan Scores were calculated. 14 were of the limited type and 14 were of the diffuse type of scleroderma. Vitamin D levels were determined in serum. Vitamin D level was measured by chemiluminescence immunometric assay. VDR gene expression was determined by quantitative PCR in isolated RNAs from the blood. Changes in mRNA levels were analysed and beta-actin was used as the housekeeping gene. Also, TGF-β1 gene expressions were determined. VDR gene expressions in diffuse type scleroderma patients were significantly decreased compared to the control. TGF-β1 gene expressions were increased in diffuse type scleroderma. It was found that VDR gene expression in limited type scleroderma patients did not show any significant difference when compared to control. Vitamin D levels and VDR gene expressions showed no correlation in scleroderma subtypes. VDR gene expression decreased in patients with diffuse type scleroderma and showed negative correlation with the Rodnan score and TGF-β1 gene expressions. There was no significant difference between vitamin D and VDR levels.