Improvement of Treg immune response after treatment with tocilizumab in giant cell arteritis

Objectives To study the percentage, suppressive function and plasticity of Treg in giant cell arteritis (GCA), and the effects of glucocorticoids and tocilizumab. Methods Blood samples were obtained from 40 controls and 43 GCA patients at baseline and after treatment with glucocorticoids + IV tocilizumab (n = 20) or glucocorticoids (n = 23). Treg percentage and phenotype were assessed by flow cytometry. Suppressive function of Treg was assessed by measuring their ability to inhibit effector T‐cell (Teff) proliferation and polarisation into Th1 and Th17 cells. Results Treg (CD4+CD25highFoxP3+) frequency in total CD4+ T cells was decreased in active GCA patients when compared to controls (2.5% vs. 4.7%, P
In this study, we demonstrated quantitative and functional disruptions in the regulatory immune response of patients with giant cell arteritis, resulting in increased proliferation and Th17 polarization of effector T cells. In addition, our results suggest that, through a specific blockade of the IL‐6 pathway, tocilizumab associated with glucocorticoids restores a better quantitative and qualitative Treg immune response than glucocorticoids alone. GCA, giant cell arteritis. Teff, effector T‐cells; Th17, T helper‐17 cells; Treg, regulatory T‐cells.