TNF and rheumatoid arthritis: To investigate the effects of direct Metrnl stimulation on cytokines and angiogenic factors secretion and expression in LPS-induced RA-FLS cells, we assessed the secretion levels of IL-17, IL-6, and TNF-α in cell supernatants by Elisa assays as well as their intracellular mRNA by RT-qPCR and protein contents by western blot.