IL6 and rheumatoid arthritis: Our data on the cytokine profile of cultured synovial explant tissues are in line with published clinical data showing that IL-6 is elevated in the synovial fluid and serum of patients with RA and OA (Houssiau et al., 1988; Pearson et al., 2017), and are consistent with previous reports demonstrating that both IL-6 and G-CSF can stimulate new vessel growth by promoting the production of VEGF (Cohen et al., 1996; Ohki et al., 2005).