In vitro response pattern of monocytes after tmTNF reverse signaling predicts response to anti-TNF therapy in rheumatoid arthritis

Background: Treatment with TNF inhibitors is very efficient in the majority of the patients with rheumatoid arthritis (RA), but it does not achieve a sufficient treatment response in 40-50% of the cases. Goal of the study was to assess functional ex vivo-tests of RA monocytes as prognostic parameters of the subsequent treatment response. Methods: 20 anti-TNF naive RA patients were enrolled in a prospective, open-label trial, and Etanercept therapy was initiated. Prior to treatment, reverse signaling was induced in peripheral blood monocytes by tmTNF crosslinking via TNFR2:Ig construct Etanercept in a standardized ex vivo-assay. Released cytokine and cytokine receptor concentrations were determined as parameters of the monocyte response. Results: Crosslinking of tmTNF and consecutive reverse signaling led to production of pro-and anti-inflammatory cytokines and of soluble cytokine decoy receptors such as sTNFR1 and sIL-1R2. Several of the measured concentrations were found to correlate with the treatment response according to the EULAR criteria. The correlation was most pronounced in sTNFR1 concentrations (r = -0.657, p = 0.0031), which also predicted a good clinical response with the highest sensitivity and specificity according to EULAR criteria. Conclusions: Herein we propose that the tmTNF crosslinking-triggered shedding of soluble decoy receptors and production of anti-inflammatory cytokines could contribute to the clinical efficacy of TNF inhibitors, and that in vitro quantification of this secretion by RA monocytes prior to treatment can be used to predict the clinical response. Further development of such standardized tests could be a step towards personalized medicine by providing rheumatologists with a rational choice for first line biological therapy in patients with RA.