V617F-independent upregulation of JAK2 gene expression in patients with inflammatory bowel disease.

Background: Inflammatory bowel disease (IBD) is one of the most important immune-mediated disorders of the gastrointestinal tract. Besides, IBD is associated with numerous extraintestinal complications such as venous thromboembolism (VTE), an important risk factor for vascular complications, which results in the increased morbidity and mortality. The JAK2 (Janus kinase 2) V617F mutation is a well-known point mutation which is involved in the pathogenesis of IBD, and VTE. Therefore, the aims of this study were to evaluate expression of JAK2 and association of V617F mutation in JAK2 of Iranian patients with IBD.

Methods: Two hundred and forty-six patients with IBD (209 UC and 37 CD) and 206 healthy controls were enrolled in this study. The genomic DNA and total RNA were extracted from peripheral blood mononuclear cells (PBMCs). Then, the JAK2 V617F mutation detection was performed using the restriction fragment length polymorphism (RFLP) method. In addition, the JAK2 mRNA expression was evaluated using a quantitative polymerase chain reaction (q-PCR) using the SYBR Green assay.

Results: There was no association of V61F mutation in patients with IBD with or without thrombosis compared with healthy control. However, the relative mRNA expression of JAK2 was significantly upregulated in patients with IBD in comparison with healthy control (P < 0.0001). In addition, the JAK2 mRNA expression was significantly decreased in patients with IBD having thrombosis compared with those without thrombosis ( P < 0.0001).

Conclusions: Taken together our findings suggested that JAK2 V61F-independent upregulation of JAK2 mRNA expression in patients with IBD. Moreover, despite the absence of JAK2 V617F mutation in patients with IBD, the increased gene expression of JAK2 can be explained by another molecular mechanism such as regulation of gene expression at the transcriptional level which may play crucial roles in the pathogenesis of IBD.