ABSTRACT
Tocilizumab, etanercept and abatacept are biological drugs used in the therapy of Rheumatoid Arthritis (RA). Their mechanism of action is well documented but their direct effects on human monocytes/macrophages have not been fully investigated. The objective of this study was to evaluate in vitro the influence of these drugs on monocytes/macrophages from healthy volunteers. Human monocytes were isolated from healthy anonymous volunteers and cultured as such or differentiated to monocyte-derived macrophages (MDMs). The effect of tocilizumab, etanercept and abatacept (at concentrations similar to those in plasma of patients) on superoxide anion production, matrix metalloproteinase-9 (MMP-9) gene expression and activity, Peroxisome Proliferator-Activated Receptor (PPAR)γ expression and cell phenotype was evaluated. Exposure of monocytes/macrophages to tocilizumab, etanercept or abatacept resulted in a significant decrease of the PMA-induced superoxide anion production. Interestingly, the expression of PPARγ was significantly increased only by tocilizumab, while etanercept was the only one able to significantly reduce MMP-9 gene expression and inhibit the LPS-induced MMP-9 activity in monocytes. When etanercept and abatacept were added to the differentiating medium, both significantly reduced the amount of CD206(+)MDM. This study demonstrates that etanercept, abatacept and tocilizumab affect differently human monocytes/macrophages. In particular, the IL-6 antagonist tocilizumab seems to be more effective in inducing an anti-inflammatory phenotype of monocytes/macrophages compared to etanercept and abatacept, also in light of the up-regulation of PPARγ whose anti-inflammatory effects are well recognised.
