Interaction between stromal cell derived factor-1 (sdf-1)‎ and chemokine receptor (cxcr4)‎ in rheumatoid arthritis

Abstract EN

Objective : Aiming to study the involvement of SDF-1 / CXCR4 interaction in the development of RA arthritis, we determined synovial SDF-1 levels to check their association with RA.

We also tried to detect the SDF-1 receptor CXCR4 expression on CD4 + CD45RO + T cells from the synovial fluid and peripheral blood using flow cytometer.

Patients and methods : the study comprised two groups : the first consisted of 12 RA patients diagnosed according to the American College of Rheumatology criteria all having knee effusion.

The second group consisted of 10 control patients who had no form of arthritis, but had slight meniscal tear or ligamentous injury with effusion.

In this study we determined SDF-1 concentration in the synovial fluid of both RA patients and controls using ELISA technique ; we also isolated CD4+CD45RO + T cells from peripheral blood (PB) and synovial fluid (SF) of patients with RA and controls and analyzed their CXCR4 expression by flow cytometer.

Results: our results showed that increased SDF-1 concentration in synovial fluid was associated with RA as the concentration of SDF-1 was significantly increased in synovial fluid of RA patients compared with controls.

RA patients had a 10.8–fold average increase in the synovial SDF-1 concentration compared with controls Statistical analysis showed a statistically significant difference between frequency of CXCR4 expression on SF T cells of RA when compared with controls (p<0.001), whereas, frequency of CXCR4 expression were not significantly different between peripheral blood of RA patients and that of the control group (p > 0.05).

However, PB T cells from RA expressed low levels of CXCR4 in contrast to SF T cells (p < 0.001).

On the other hand, PB T cells from controls did not show any significant difference in CXCR4 expression in contrast to their SF T cells (p > 0.05).

Conclusion : our results indicate that the interaction between CXCR4 and its ligand SDF-1 may play a crucial role in RA joint inflammation.

Inflammation in RA appears to persist as a direct result of the sustained recruitment, inappropriate retention, and active survival of highly differentiated T cells mediated by stromal-derived factors associated with the inflamed synovial joint itself.

Therefore, targeting the synovial stromal microenvironment represents an important alternative therapeutic strategy in chronically inflamed joints.