Effects of different moxibustion time on knee cartilage morphology and the expression of TNF-α and IL-10 in rats with knee osteoarthritis

Objective To observe the effects of different moxibustion time on cartilage morphology, tumor necrosis factor (TNF)-α and interleukin (IL)-10 of the knee joint in rats with knee osteoarthritis (KOA), and to explore the best treatment time of moxibustion for KOA. Methods Healthy male Wistar rats were randomly divided into a blank group, a model group, a 15-minute-moxibustion group, a 30-minute-moxibustion group, and a 60-minute-moxibustion group, with 10 rats in each group. Except for the blank group, the KOA model was established in all groups by injecting sodium iodoacetate solution into the knee joint cavity of rats. Rats in the 15-minute-moxibustion group, the 30-minute-moxibustion group, and the 60-minute-moxibustion group were all treated with mild moxibustion intervention for 15 min, 30 min, and 60 min, respectively at Neixiyan (EX-LE4) and Dubi (ST35) points near the patella, 3 times a week for 4 weeks, 12 times in total. Rats in the blank group and the model group were fixed for 30 min without moxibustion intervention. Macroscopic observation for the smoothness of knee cartilage surface was performed after the intervention. Hematoxylin-eosin staining, toluidine blue staining, and Mankin score were used to evaluate the pathological changes in the cartilage. The expression levels of TNF-α and IL-10 in the serum were detected by enzyme-linked immunosorbent assay. Results Compared with the blank group, the articular cartilage surface in the model group was rough, the chondrocyte arrangement was irregular, the Mankin score and the serum TNF-α expression were significantly increased ( P <0.05), while the expression of serum IL-10 was significantly decreased ( P <0.05). Compared with the model group, the articular cartilage surface was smoother, the chondrocytes were arranged neatly, the Mankin score and serum TNF-α expression level were significantly lower in the three moxibustion intervention groups ( P <0.05); the serum IL-10 level in the 30-minute-moxibustion group and the 60-minute-moxibustion group was increased significantly ( P <0.05). Compared with the 15-minute-moxibustion group, the articular cartilage surface in the 30-minute-moxibustion group and the 60-minute-moxibustion group was smoother, the chondrocyte arrangement was more regular, the Mankin score and the serum TNF-α level were decreased significantly ( P <0.05), and the serum IL-10 level was increased ( P <0.05). There was no significant difference in the serum TNF-α or IL-10 level between the 30-minute-moxibustion group and the 60-minute-moxibustion group ( P >0.05). Conclusion Moxibustion can obviously improve the morphology and structure of KOA articular cartilage, protect articular cartilage, inhibit cartilage inflammation, and delay KOA cartilage degeneration. Moxibustion’s effect is closely related to moxibustion time; the therapeutic effect of the 30-minute-moxibustion and the 60-minute- moxibustion is better than that of the 15-minute-moxibustion.