Objective

This study was done to determine the effects of different courses of moxibustion on a rat knee osteoarthritis (KOA) model, and explore the dose-effect relationship of moxibustion on KOA from the perspectives of intestinal flora and inflammatory factors.

Methods

Wistar rats were randomly divided into five groups: normal, model, moxibustion for 2 weeks, moxibustion for 4 weeks and moxibustion for 6 weeks groups (n = 5 each group). A KOA rat model was induced by monosodium iodoacetate, and moxibustion intervention was performed at the acupoints “Dubi” (ST35) and “Zusanli” (ST36), once every other day. Pathologic changes in the cartilage of rat knee joints were assessed after intervention, and fecal samples were subjected to 16S rRNA high-throughput sequencing for microbial diversity analysis.

Results

Damage to the knee articular cartilage was obvious in the model group, which also had increased levels of pro-inflammatory factors, decreased levels of anti-inflammatory factors, and intestinal flora disorders with decreased diversity. The degree of cartilage damage in the 4 and 6 weeks of moxibustion groups was significantly improved compared with the model group. The 4 and 6 weeks of moxibustion groups also demonstrated reduced levels of interleukin-1β and tumor necrosis factor-α and increased levels of interleukin-10 (P < 0.05). Both the abundance and diversity of the intestinal flora were increased, approaching those of the normal group. Abundances of probiotics Eubacterium coprostanoligenes group and Ruminococcaceae UCG-014 increased, while that of the pathogenic bacteria Lachnospiraceae NK4A136 group decreased (P < 0.05). Although the abundance of Lachnospiraceae NK4A136 group decreased in the 2 weeks of moxibustion group compared with the model group (P < 0.05), there was no statistically significant difference in serum inflammatory factors, flora species diversity or degree of pathological damage compared with the model group.

Conclusion

Moxibustion treatment led to significant improvements in the intestinal flora and inflammatory factors of rats with KOA. Moxibustion treatment of 4 and 6 weeks led to better outcomes than the 2-week course. Moxibustion for 4 and 6 weeks can regulate intestinal flora dysfunction with increased probiotics and reduced pathogenic bacteria, reduce pro-inflammatory factors and increase anti-inflammatory factors. No significant differences were seen between the effects of moxibustion for 4 weeks and 6 weeks.

Key words: Knee osteoarthritis, Different courses, Moxibustion treatment, Intestinal flora, Inflammatory cytokines