Background Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by synovial hyperplasia, mononuclear cell infiltration, bone erosion and joint destruction. We have shown recently that positive response to methotrexate therapy in RA patients during 24 months of follow-up was associated with downregulation of TNFα gene expression measured in the peripheral blood mononuclear cells (PBMCs) to the level of healthy controls. In contrast, upregulation of MMP-9 and cathepsin K gene expression in the PBMCs of seropositive RA patients treated with methotrexate for 24 months was associated with an increase in erosion numbers compared to baseline (1).
Objectives Here we hypothesized that changes in expression of the genes responsible for bone and articular cartilage resorption (MMP-9, cathepsin K), and inflammation (TNFα, IL6) in the PBMCs obtained at baseline from RA patients and cultured with an anti-rheumatic drug might be associated with treatment outcome.
Methods 13 RA patients aged 53.4±10.8 years old, disease duration 8.2±7.1 years (with previous history of treatment with DMARDs) were examined. Control group consisted of 26 healthy subjects. PBMCs were fractionated on Ficoll density gradient and cultured with 1 nM rapamycin (RAP), 10 μM chloroquine diphosphate (CQ) or 1 μM desferrioxamine mesylate (DFO) during 48h. Cell viability was monitored by 0.2% Trypan blue staining. Total RNA isolated from these cells was used for MMP-9, cathepsin K, TNFα, and IL6 gene expression studies performed with quantitative Real-time RT-PCR.
Results At baseline expression of all the examined genes measured in the PBMCs was significantly upregulated (p<0.05) in the examined RA patients compared to healthy subjects. RAP, CQ, or DFO were capable of altering gene expression in cultured PBMCs from these RA patients compared to untreated cells. Downregulation of a target gene expression in cultured PBMCs by each of the examined drugs, namely, mechanistic target of rapamycin (mTOR) for RAP, autophagy-related ULK1 for CQ, or cyclin-dependent kinase inhibitor 1 (p21) for DFO was associated with significant inhibition of pro-inflammatory cytokine (TNFα, IL6) and/or genes involved in joint destruction (MMP-9, cathepsin K) expression compared to untreated counterparts. The absence of the drug effect on the target gene expression was accompanied by the lack of any change in gene expression of the examined proinflammatory mediators and genes associated with cartilage and bone turnover.
Conclusions Analysis of gene expression changes in cultured cells of RA patients in the presence of an antirheumatic drug before treatment might indicate the efficacy of this drug in the personalised therapy.
Tchetina EV, Demidova NV, Karateev DE, Nasonov EL. Rheumatoid Factor Positivity Is Associated with Increased Joint Destruction and Upregulation of Matrix Metalloproteinase 9 and Cathepsin K Gene Expression in the Peripheral Blood in Rheumatoid Arthritic Patients Treated with Methotrexate. Int J Rheumatol, 2013; 2013:45787
Acknowledgements This study was funded by Russian Foundation for Basic Research (project no. 12-04-00038-a to EVT).
Disclosure of Interest None declared