Objective: It has been suggested that patients with rheumatoid arthritis (RA) with abundant tumor necrosis factor-alpha (TNF-alpha) are more likely to respond to TNF-alpha inhibitors. We measured expression of TNF-alpha mRNA in peripheral blood of RA patients undergoing infliximab treatment in order to test its predictive value for treatment response.
Methods: Forty-four RA patients showing persistent disease activity and 27 healthy controls were studied. Peripheral blood TNF-alpha mRNA levels were measured before and 4 hours after the first infliximab infusion and at Week 22 using quantitative RT-PCR. Results were correlated to the treatment response at Week 22 in the whole RA cohort and a subset of patients showing high TNF-alpha mRNA levels at baseline.
Results: At baseline and at Week 22, TNF-alpha mRNA expression in RA patients was significantly increased compared to healthy controls. At both timepoints, no significant difference was observed between responders and nonresponders. Compared to baseline, infliximab treatment induced a decrease in TNF-alpha mRNA level at 4 hours and at Week 22, although this effect was significant only in patients with high TNF-alpha mRNA expression at baseline. Such variation compared to baseline was similar in responders and nonresponders.
Conclusion: Peripheral blood TNF-alpha mRNA expression is increased in RA, but its reduction with anti-TNF treatment is not associated with treatment response.