NOS2 and rheumatoid arthritis: In summary, our study showed, for the first time, the beneficial effects of dietary Per-OL and OL supplementation in CIA model of RA by reducing arthritic damage, serum pro-inflammatory biomarkers (MMP-3 and COMP), cytokines production (IL-6, IL-1β, TNF-α, IFN-γ, IL-17), and inhibiting both iNOS and COX-2 overexpression.