ASSOCIATION OF BLOOD GENE EXPRESSIONS IN RHEUMATOID ARTHRITIS PATIENTS WITH CLINICAL AND LABORATORY PARAMETERS BEFORE AND AFTER METHOTREXATE THERAPY

Abstract

The genes, the high basic expression of which indicates the efficiency of methotrexate (MTX) therapy in relieving joint inflammation and destruction in patients with rheumatoid arthritis (RA), have been defined.Objective: to find an association between the initial expression of the genes: mTOR (mammalian target of rapamycin), a major regulator of cell growth and proliferation; ULK1 (an autophagy marker 1); p21 (a cyclin-dependent kinase inhibitor); kaspase-3 (an apoptosis activity indicator); MMP-9 (matrix metalloproteinase 9), and cathepsin K, which are involved in joint destruction, and the cytokines: TNF-α (tumor necrosis factor-α), TGFβ1 (transforming growth factor β1) and Runx2 (Runt-related transcription factor 2) in the blood of RA patients with disease activity and joint destruction before and after MTX therapy during 24 months.Subjects and methods. Forty patients (mean age, 47.5 years) with RA lasting < 2 years) and 26 healthy donors (mean age, 45.1 years) were examined. All the patients took MTX for 2 years. A clinical response was assessed with disease activity score (DAS28); erythrocyte sedimentation rate and the serum levels of anti-cyclic citrullinated peptide antibodies (ACCPA), C-reactive protein (CRP), and rheumatoid factor (RF) were also estimated. Joint destructive changes were assessed by radiography. Furthermore, blood and knee articular cartilage samples from 21 patients (mean age, 50.4 years) with late-stage RA and cartilage samples from 25 healthy individuals were investigated. Gene expression in the cells of peripheral blood and cartilage was determined by real-time reverse transcriptase polymerase chain reaction.Results and discussion. MTX therapy considerably reduced disease activity assessed by DAS28, CRP levels, stiffness, tender and swollen joint counts (TJC and SJC); however, joint space (JS) narrowing (JSN) substantially increased compared with the baseline values. The expression of the ULK1, p21, MMP-9, cathepsin K genes, and TGFβ1 was increased both at the beginning of the investigation and 24 months later whereas the initially higher expression of mTOR, TNF-α, caspase 3, and Runx2 was decreased by the end of therapy to the level of the healthy individuals. The initial expression of the TGFβ1, Runx2, caspase 3, and р21 genes correlated negatively with the RF level measured both at the beginning of the investigation and 24 months later. There was a positive correlation of the initial expression of ULK1 and MMP-9 with CRP levels prior to therapy and that of the initial expression of MMP-9 with baseline DAS28 scores and NSJ. Moreover, the initial expression of the TNF-α gene positively correlated with JSN at the end of therapy and that of the p21, caspase 3, and Runx2 genes with a change in DAS28. There was also a negative correlation of the initial expression of the mTOR gene with the SJC and the number of erosions; the p21 and TNF-α genes correlated negatively with SJC and TJC; and the TNF-α, TGFβ1, Runx2, and cathepsin K genes also negatively correlated to the duration of stiffness at the end of therapy. A positive correlation was found between the expression of the cathepsin K and TGFβ1 genes in the blood and articular cartilage of patients with late-stage RA.Conclusion. The expression of the MMP-9 and ULK1 genes is associated with disease activity. The high initial blood expression of the other examined genes is associated with the more effective action of MTX on stiffness (TNF-α, Runx2, cathepsin K, and TGFβ1), TJC and SJC (mTOR, p21, and TNF-α), and the progression of joint destruction (mTOR) and may play a protective role. The positive correlation of the blood and articular cartilage expression of the TGFβ1 and cathepsin K genes may point to their co-regulation in these tissues in RA.

Keywords

• rheumatoid arthritis
• gene expression
• peripheral blood
• inflammation
• joint injury
• methotrexate