Targeting IL-6 signalling in early rheumatoid arthritis is followed by Th1 and Th17 suppression and Th2 expansion

OBJECTIVES: To investigate the in vitro and ex-vivo effect of IL-6 inhibition on the balance between Th1, Th2, Th17 and Treg cells. METHODS: Ten consecutive adult patients with active early rheumatoid arthritis (ERA) and ten healthy volunteers were included in the study. The percentages of Th1, Th2, Th17 and Treg cells were analysed by flow cytometry in the peripheral blood mononuclear cells obtained from controls and from RA patients at the time of first evaluation and just before the third TCZ infusion. The in vitro effect of TCZ on the different subsets of CD4+ T cells and the expression levels of Th1, Th2, Th17 and Treg-related cytokines was also assessed. RESULTS: Treatment with TCZ, both ex vivo and in vitro, resulted in a significant reduction of the percentage of Th1, Th17 and Treg cells with a concomitant significant increase of Th2 cell subsets. The reduction of the different subsets of T lymphocytes was associated with an intense staining with Annexin V, suggesting an apoptotic-related cell reduction. A significant decrease of Th1, Th17 and Treg cytokines and a concomitant increase of IL-4 was also observed after TCZ treatment in PBMC isolated from RA patients. CONCLUSIONS: TCZ could modify the immune imbalance in RA inducing apoptosis of Th1, Th17 and Treg cells and promoting the appearance of a Th2 response.