Elevated Level of Interleukin-29: A Proinflammatory Role in Synovial Inflammation of Rheumatoid Arthritis

Abstract

Background: The multiple pro-inflammatory cascades described in RA lead to persistent synovitis, resulting in articular cartilage and bone damages. The up-regulation of interferon-inducible genes has been found in the synovial lining regions and may play an important role in the pathogenesis of RA. Objective: The aim of the current study is to examine the expression of IL-29 and its receptors IL-28Rα in blood and synovial fluid (SF) in RA patients and investigate the correlation of IL-29 with disease activity and other laboratory characters of RA. Methods: The study was carried out on 108 RA patients, 70 OA patients and 80 healthy control subjects. Clinical assessment of disease activity in RA patients and disease activity score with DAS28 had been done. IL29 was detected in the serum and synovial fluid of all samples by ELISA. Real time PCR was used for human IL-29 and IL-28Rα expression from PBMC. Results: expression of IL-29 mRNA was significantly higher in RA PBMCs when compared to OA and HC (132±13.8, 49± 11.2, 33.3± 10.5; respectively P <0.05). Similarly, IL-28Rα mRNA expression was significantly higher in RA PBMCs when compared to OA and HC (30.5±9.7, 13.3±4.5, 8.5± 3.3; respectively P <0.05). The mean level of IL-29 in SF was increased in RA and found also much higher in RA (17.29 ± 10.19pg/ml) than OA (8.33 ±3.89 pg/ml) (P = 0.01). There is a significant correlation between serum levels of circulating IL- 29 and DAS28, CRP, ESR, RF, and anti-CCP. Conclusion: our data have presented new evidence that IL-29 may contribute to RA pathogenesis