A dietary polysaccharide from Eucheuma cottonii downregulates proinflammatory cytokines and ameliorates osteoarthritis-associated cartilage degradation in obese rats
Osteoarthritis (OA) is a common form of arthritis diseases, characterized by degeneration of articular cartilage, and leading to joint dysfunction. Oral drugs therapy seems to ameliorate some signs and symptoms of OA, but it might be accompanied by side effects and seem not effective for a long time. Seaweeds have received much concern in the pharmacological application due to its various biomedical properties, including the anti-inflammation, antitumor, and antioxidant effects. This study investigated the ameliorative effects of a dietary polysaccharide from Eucheuma cottonii extract (ECE) on an anterior cruciate ligament transection with partial medial meniscectomy surgery (ACLT+MMx) to induce OA in high-fat diet (HFD)-induced obese rats. The male Sprague–Dawley rats were fed an HFD for 12 weeks before ACLT+MMx surgery, after which they were administered a daily oral gavage of saline (Sham, OB Sham, OBOA), either low-dose ECE (100 mg/kg body weight) or high-dose ECE (400 mg/kg body weight), or glucosamine sulfate as a positive control (OBOAGS; 200 mg/kg body weight) for 5 weeks. Treatment with ECEs decreased the body weight, triglyceride and total cholesterol (TC) levels, and the TC/high-density lipoprotein (HDL)-C ratio in obese rats. Additionally, ECE downregulated the expression of proinflammatory cytokines, including tumor necrosis factor-α, interleukin-1β, and leptin, and suppressed nuclear factor-kappa B and extracellular-signal-regulated kinase-1/2 expression, resulting in decreased levels of matrix metalloproteinase (MMP)-1 and -13 and prostaglandin-E2 and attenuated cartilage degradation. These results demonstrated that the dietary polysaccharide from ECE suppressed OA development in obese rats, suggesting its potential efficacy as a promising candidate for OA treatment.