Meloxicam ameliorates the cartilage and subchondral bone deterioration in monoiodoacetate-induced rat osteoarthritis

OBJECTIVE This study aimed to quantify the cartilage- and subchondral bone-related effects of low-dose and high-dose meloxicam treatment in the late phase of mono-iodoacetate-induced osteoarthritis of the stifle. METHODS Thirty-four male Wistar rats received intra-articular injection of mono-iodoacetate to trigger osteoarthritis; 10 control animals (Grp Co) received saline. The mono-iodoacetate-injected rats were assigned to three groups and treated from week 4 to the end of week 7 with placebo (Grp P, n = 11), low-dose (GrpM Lo, 0.2 mg/kg, n = 12) or high-dose (GrpM Hi, 1 mg/kg, n = 11) meloxicam. After a period of 4 additional weeks (end of week 11) the animals were sacrificed, and the stifle joints were examined histologically and immunohistochemically for cyclooxygenase 2, in conformity with recommendations of the Osteoarthritis Research Society International. Serum cytokines IL-6, TNFα and IL-10 were measured at the end of weeks 3, 7, and 11. RESULTS Compared with saline-treated controls, animals treated with mono-iodoacetate developed various degrees of osteoarthritis. The cartilage degeneration score and the total cartilage degeneration width were significantly lower in both the low-dose (p = 0.012 and p = 0.014) and high-dose (p = 0.003 and p = 0.006) meloxicam-treated groups than in the placebo group. In the subchondral bone, only high-dose meloxicam exerted a significant protective effect (p = 0.011). Low-grade Cox-2 expression observed in placebo-treated animals was abolished in both meloxicam groups. Increase with borderline significance of TNFα in GrpP from week 3 to week 7 (p = 0.049) and reduction of IL-6 in GrpM Lo from week 3 to week 11 (p = 0.044) were observed. CONCLUSION In this rat model of osteoarthritis, both low-dose and high-dose meloxicam had a chondroprotective effect, and the high dose also protected against subchondral bone lesions. The results suggest a superior protection of the high-dose meloxicam arresting the low-grade inflammatory pathway accompanied by chronic cartilage deterioration.