VDR and TNFα promoter methylation and expression level in atients with Bechet's Disease can act as diagnostic biomarkers

Abstract

Behcet’s disease (BD) is a chronic relapsing multisystem auto-inflammatory disease with unknown etiology, characterized by recurrent oral aphthous ulcers, genital ulcers and uveitis. However, environmental factors especially microbial agents, genetic factors and epigenetic changes contribute to disease development. DNA methylation is one of the epigenetic biomarker. TNFα is a multi-potential pro-inflammatory cytokine that mediates primarily response in acute phase of inflammation.The evidence suggests that TNFα may play a crucial role in the pathogenesis of BD. Association between TNFα promoter polymorphisms and susceptibility to BD. VDR is a DNA binding transcription factor of the nuclear superfamily, which mediate 1α, 25(OH)2D3 signaling. Vitamin D through VDR can regulate: the proliferation, differentiation and function of immune cells. Also, VDR has an anti-inflammatory and immunoregulatory role via interaction with other transcription factor such as NF- kB, NFAT and glucocorticoids receptor or cell signaling pathway such MAP kinase, SOCS and P38 in immune system. The aim of our study is to analyze the expression level and methylation of the VDR and TNFα genes promoter in peripheral blood mononuclear cells of patients with BD. Materials and Methods: In a case–control study, 48 Iranian Azari BD patients and 60 ages-, sex- and ethnically-matched healthy controls were included. Venous blood samples were collected and peripheral blood mononuclear cells (PBMC) were isolated by Ficoll protocol. The DNA and RNA were subsequently extracted. Promoter methylation levels were evaluated by MeDIP-qPCR. The expression of VDR and TNFα were evaluated by Real-time PCR. Results: The results of quantitative real-time PCR analysis showed that no significant difference was observed in the DNA methylation levels in the BD and control groups (p > 0.05). VDR gene expression levels of the BD patients were significantly lower compared with those in the control group (P= 0.013). Also, the results showed that significantly higher expression levels of TNFα gene (P=0.00) and significantly lower promoter methylation levels in patient of BD compared with those in the control group (P=0.001). Conclusion: The results of VDR and TNFα genes Promoter methylation and expression in this study shows, that the expression level of genes probably cannot regulated by a unique DNA methylation mechanism. More studies are needed to determine the role of promoter methylation in inflammatory disease conditions.