Possible Anti-inflammatory Effects of Mesenchymal Stem Cells Transplantation via Changes in CXCL8 Levels in Patients with Refractory Rheumatoid Arthritis

The synovial- lining cells have been involved with rheumatoid arthritis (RA) through the secretion of various cytokines and chemokines. Increased levels of these cytokines and chemokines are seen first in the synovial and subsequently in the bloodstream of RA patients. The synovial and circulating levels of CXCL8, CXCL12, and CXCL13 are higher in the RA patients than in the healthy subjects, causing migration of immune cells to the joints, which is associated with increased joint destruction. We aimed to evaluate the effects of autologous mesenchymal stem cells intravenous administration on plasma levels of CXCL8, CXCL12 and CXCL13 at 1, 6, and 12 month follow-up periods in refractory RA patients. 13 patients with refractory RA received autologous mesenchymal stem cells (MSCs). The ELISA technique was used to evaluate the plasma level of these chemokines. CXCL8 levels were significantly decreased at month 6 after MSCs transplantation in comparison with pre-injection level, and the concentration of this chemokine was significantly increased at month 12 in comparison with the month 6 after injection (P <0.05). The levels of CXCL12 and CXCL13 were insignificantly decreased at months 1 and 6 after the MSCs transplantation. The interaction of MSCs after migration to the inflamed joints with CXCL8-producing cells could be one but not the only possible mechanism that reduces its production in the joints and subsequently in the plasma of RA patients. CXCL8 reduction as a consequence of MSCs application returned to pre-injection levels after 12 months. Therefore, increasing the dose of MSCs and replication of injections may maintain the potential anti-inflammatory effects of MSCs on the production of CXCL8 as an inflammatory mediator in patients with refractory RA.