ENHO gene expression and serum adropin level in rheumatoid arthritis and systemic lupus erythematosus

Background. Adropin, a secreted protein, is encoded by the energy homeostasis-associated gene (ENHO). It is expressed by a variety of tissues and cells. It has been implicated in several physiological and pathological processes, such as angiogenesis and apoptosis. Objectives. The aim of the present study was to investigate the ENHO gene expression and serum adropin levels in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Material and methods. The study included 36 patients with RA, 22 patients with SLE and 20 healthy controls (HC). Patients with a disease activity score-28-erythrocyte sedimentation rate (DAS28-ESR) > 2.6 in the RA group and an SLE disease activity index (SLEDAI) > 6 in the SLE group were accepted as active. Serum adropin levels were analyzed by the enzyme-linked immunosorbent assay (ELISA) method. The ENHO gene and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene expressions in peripheral blood mononuclear cells were analyzed by real-time polymerase chain reaction (PCR). Results. The ENHO gene mRNA expression was significantly higher in the RA group than in the HC group (p = 0.024), although it was similar between the SLE and HC groups (p = 0.920). On the other hand, there were no significant differences among the study groups in terms of serum adropin levels (p > 0.05 for all). Moreover, there was no significant difference in terms of the ENHO expression and serum adropin levels between active and inactive RA and SLE patients. Conclusions. Although the ENHO gene expression is increased, serum adropin level is not altered in RA. Similarly, adropin seems not to be associated with SLE. However, the potential link between adropin and inflammatory diseases need to be tested in further studies.