Oleuropein or rutin consumption decreases the spontaneous development of OA in hartley guinea pig

      Purpose: Osteoarthritis is a high prevalence disease characterized by a progressive loss of articular cartilage. Cartilage degradation is associated with structural and metabolic changes in joint tissues such as cartilage, subchondral bone and synovial membrane inflammation. One reliable model to investigate the natural course of the disease and to study the effects of treatments is Dunkin-Hartley guinea pigs developing spontaneous knee osteoarthritis which mimics the pathophysiological processes of human osteoarthritis. The potential protective effects of three polyphenols found in olive oil (oleuropein) or fruits and vegetables (rutin and curcumin) were assessed on this joint ageing and osteoarthritis development model.
      Methods: Sixty four-week old Dunkin-Hartley guinea pigs were randomized into four groups and received daily during 31 weeks either standard guinea pig diet (control group) or a standard guinea pig diet enriched with oleuropein (0.025 %), rutin (0.5%) or rutin/curcumin (0.5% / 0.25%) association. Animals were weighed each week and blood samples taken every 6 weeks and at the time of euthanasia (week 35). Biomarkers of osteoarthritis (COLL2-1, COLL2-1NO2, Fib3-1, Fib3-2) as well as inflammation (PGE2) were quantified in the serum. Histological assessments of knee cartilage and synovial membrane were performed at week 35.
      Results: At week 35, guinea pigs in the control group spontaneously developed significant cartilage lesions with mild synovial inflammation. The histological scores of cartilage lesions and synovitis were well correlated with the increased level of serum biomarkers. Histologically, all treatments significantly reduced the cartilage degradation score (p < 0.01), but only oleuropein significantly decreased synovitis (p < 0.05) compared to the control group. Furthermore, oleuropein decreased serum PGE2 levels at week 35 (p < 0.01). Serum COLL2-1 and Fib3-1 were decreased by rutin and the combination of rutin and curcumin, Fib3-2 was only decreased by the combination of rutin and curcumin, while COLL2-1NO2 was significantly decreased by all treatments (p < 0.05).
      Conclusions: Oleuropein and rutin with or without curcumin significantly slowed down the progression of spontaneous osteoarthritis lesions in guinea pigs. While no additive effect was seen in the curcumin and rutin group, the differential effects of oleuropein or rutin on inflammatory and cartilage catabolic markers suggest an interesting combination for future studies in osteoarthritis protection.