Investigation of the Relationship Between Serum Orosomucoid-1 (ORM1) Levels and Methylation of ORM1 Gene Promoter in Patients with Rheumatoid Arthritis

Abstract

Objective: Rheumatoid arthritis (RA) is a chronic inflammatory disease, and genetic and environmental factors are well-known causes. Orosomucoid-1 (ORM1) is an acute phase response protein with anti-inflammatory properties and associated with the RA pathogenesis. However, its role in RA has not been fully known. In this study, we aimed to investigate serum ORM1 levels and methy-lation of ORM1 gene promoter in RA patients and healthy controls. Material and Methods: The study group consisted of 40 RA patients and 31 healthy controls. Serum levels of ORM1 in RA patients and healthy controls were determined by using the ELISA method. After genomic DNA was isolated from blood samples, DNA samples were modified with bisulfite. Promoter methylation of ORM1 was analyzed by methylation-specific PCR using methylation-specific primers designed for the ORM1 promoter region. Results: The serum levels of ORM1 in control group were found approximately 3.2 times higher compared to the patient group (p<0.001). The fre-quency of methylation of the ORM1 gene promoter was 70% in RA patients and 35.5% in the control group. Consequently, hypermethy-lation for RA patients and hypomethylation for the control group were observed in the ORM1 promoter. Conclusion: The serum levels of ORM1 are much lower in the patient group than the control, suggesting that methylation of ORM1 promoter plays an essential role in regulating gene expression and in the inflammatory response. Since epigenetic changes occur before the onset of clinical signs of RA, the methylation status of ORM1 might be a clinical biomarker for RA. © 2020 by Türkiye Klinikleri.