IL6 and rheumatoid arthritis: The increase of pro-inflammatory cytokines expression such as TNF-α, IL-1β, IL-6 and IL-17, inflammatory mediators like COX-2 and 5-LOX (5-lipoxygenase), as well as the reduction of anti-inflammatory markers such as IL-4 and IL-10 are the hallmark of synovial inflammation and cartilage damages and are extensively monitored parameters in in vivo RA models [36,37].