Abstract
Osteoarthritis (OA), the most common type of arthritis, is a disabling progressive disease mainly affecting the elderly and is becoming a major public health problem. Current therapies for OA provide only palliative pain relief and therapeutic candidates that are able to slow the progression of structural deterioration is a major unmet need for this disorder. Avocado soybean unsaponifiables (ASU) has proven its safety and effectiveness in clinical studies of knee osteoarthritis (OA); however, whether ASU exerts structure-modifying effects is still to be elucidated. There are limited studies that have explored the underlying mechanisms of ASU's beneficial effects in animal models of OA. To this end, this study is the first to evaluate the effects of ASU in a rat model of mono-iodoacetate (MIA)-induced knee OA. OA was induced in rats by knee intra-patellar injection of MIA. Oral administration of ASU (27.5 mg/kg per day for 3 weeks) was initiated 3 weeks after MIA injection. We analysed the knee samples using light and electron microscopy. In addition, we used immunohistochemistry to investigate the expression of inducible nitric oxide synthase (iNOS), tumour necrosis factor-a (TNF-a), and matrix metalloproteinase-13 (MMP-13) in OA cartilage and subchondral bone. ASU significantly attenuated the synovium, cartilage, and subchondral degeneration. In addition, it reduced the expression of TNF-a and MMP-13 in OA cartilage and the expression of iNOS in both OA cartilage and subchondral bone. These results provide evidence of the structure-modifying abilities of ASU via its anti-oxidative and anti-inflammatory properties, in addition to its ability to modulate MMP-13 activity. This work suggests that ASU can be used as a potential disease-modifying treatment for OA.