An Assessment of BHLHE40 Transcription Factor Level and its Target Cytokines in Patients with Rheumatoid Arthritis

Background: Basic helix-loop-helix protein 40 (BHLHE40) can function as both a transcriptional activator and repressor. Recent studies have reported its regulatory functions in T helper (Th)1 and Th17 immune responses. Rheumatoid arthritis (RA) is an autoimmune inflammatory disease in which joints are involved. Both Th1 and Th17 contribute to the pathogenesis of the disease. In the present study, the levels of BHLHE40, interleukin 17 (IL-17), and interferon-gamma (IFN-γ) were assessed in the RA patients. Methods: Two groups, including RA patients and healthy individuals, were included in the study. The relative expression levels of BHLHE40, IL-17, and IFN-γ were quantified in peripheral blood mononuclear cells (PBMCs) using real-time PCR. Results: The results showed that the level of BHLHE40 was significantly higher in RA patients compared to the healthy control (P < 0.001) (11.1-fold increase). Accordingly, a significant increase in the levels of IL-17 (8.1 folds increase) (P < 0.021) and IFN-γ (12.7 folds) (P < 0.001) was observed. Conclusion: Evaluation of the expression level of BHLHE40 in RA patients showed a significant increase. In line with the elevated level of BHLHE40, a significant increase in the expression level of IL-17 and IFN-γ was also detected. These findings point to the possible role of BHLHE40 in the disease course or severity by elevating the levels of inflammatory cytokines, including IL-17 and IFN-γ. Therefore, BHLHE40 might be considered either as a putative biomarker or as a candidate for therapy in a variety of human diseases.