Anti-inflammatory and joint protective effects of extra-virgin olive-oil polyphenol extract in experimental arthritis

The consumption of extra virgin olive oil (EVOO) in Mediterranean countries has shown beneficial effects. A wide range of evidence indicates that phenolic compounds present in EVOO are endowed with anti-inflammatory properties. In this work, we evaluated the effects of EVOO-polyphenol extract (PE) in a model of rheumatoid arthritis, the collagen-induced arthritis model in mice. On day 0, DBA-1/J mice were immunized with bovine type II collagen. On day 21, mice received a booster injection. PE (100 and 200 mg/kg) was orally administered once a day from days 29 to 41 to arthritic mice. We have demonstrated that PE decreases joint edema, cell migration, cartilage degradation and bone erosion. PE significantly reduced the levels of proinflammatory cytokines and prostaglandin E2 in the joint as well as the expression of cyclooxygenase-2 and microsomal prostaglandin E synthase-1. Our data indicate that PE inhibits c-Jun N-terminal kinase, p38 and signal transducer and activator of transcription-3. In addition, PE decreases nuclear factor κB translocation leading to the down-regulation of the arthritic process. These results support the interest of natural diet components in the development of therapeutic products for arthritic conditions.