IL1B and rheumatoid arthritis: In contrast, in synovial tissue of RA patients, the proinflammatory mediators IL-1β, TNF-α, and 5-LOX were elevated approximately 5- to 13-fold compared to controls, whereas the anti-inflammatory mediators 15-LOX, FPR2, and IL-10 were upregulated approximately 3- to 7-fold (Figure 7).