Electroacupuncture Prevents Osteoarthritis of High-Fat Diet-Induced Obese Rats

Abstract

The effects of acupuncture on osteoarthritis (OA) pathogenesis have been demonstrated in vitro and in animal models. However, the potential for acupuncture to mediate protective effects on obese-induced OA has not been examined. Here, we investigated the effects of different acupuncture patterns on OA pathogenesis in high-fat diet- (HFD-) induced obese rats. After 12-week diet-induced obesity, obese rats were treated with three acupuncture protocols for 2 weeks, including ST36, GB34, and ST36+GB34. The results showed that the three acupuncture protocols both prevented obesity-induced cartilage matrix degradation and MMP expression and mitigated obesity-induced systemic and local inflammation but had different regulatory effects on lipid metabolism and gut microbiota disorder of obese-induced OA rats. Furthermore, the three acupuncture protocols increased the microbial diversity and altered the structure of community of feces in obese rats. We found that ST36 and GB34 could inhibit proinflammatory shift in the gut microbiome with an increase in the ratio of Bacteroidetes/Firmicutes and promote the recovery of relative abundance of Clostridium, Akkermansia, Butyricimonas, and Lactococcus. Although both ST36 and GB34 had an anti-inflammatory effect on serum inflammatory mediators, only the acupuncture protocol with both ST36 and GB34 could effectively inhibit LPS-mediated joint inflammation in obesity rats. Therefore, relieving obesity-related chronic inflammation, lipid metabolism disorder, and gut microbiota disorder may be an important mechanism for acupuncture with ST36 and GB34 to promote OA recovery.

Figure 1

Effect of electroacupuncture on body weight and the lipid metabolic profile of obese rats. (a) After 12-week feeding, body weight of rats fed with HFD gradually increased to be overweight than that of chow-fed rats. Data were expressed as mean ± SD (6 rats in control and 24 rats in HFD); ^∗p < 0.05, ^∗∗p < 0.01, and ^∗∗∗p < 0.001 analyzed by two-tailed Student's t-test. (b) Body weights were measured after 2-week electroacupuncture treatments. (c) Serum levels of total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL), and low-density lipoprotein (LDL) were measured after 2-week electroacupuncture treatments. All data are expressed as the mean ± SD (n = 6 per group). Post hoc ANOVA was used to test for statistical significance. ^∗p < 0.05, ^∗∗p < 0.01, and ^∗∗∗p < 0.001 versus the control group; ^#p < 0.05, ^##p < 0.01, and ^###p < 0.001 versus the DIO-KOA group.

Figure 2

Electroacupuncture prevents cartilage loss in the OA of diet-induced obesity rats. (a) Representative safranin-O/fast green-stained sections. Scale bar = 200 μm. (b) Quantification of modified total Mankin scores. (c) Representative sections of knee joints that were stained for MMP-1 and MMP-13. Scale bar = 40 μm. (d) The integral absorbency of MMP-1 in cartilage areas. (e) The integral absorbency of MMP-13 in cartilage areas. All data are expressed as the mean ± SD (n = 6 per group). Post hoc ANOVA was used to test for statistical significance. ^∗p < 0.05, ^∗∗p < 0.01, and ^∗∗∗p < 0.001 versus the control group; ^#p < 0.05, ^##p < 0.01, and ^###p < 0.001 versus the DIO-KOA group.

Figure 3

Electroacupuncture attenuated systemic and knee inflammation of obese rats. (a) Serum inflammatory markers. (b) Synovial fluid inflammatory markers. (c) Serum and synovial fluid LPS level. (d) Western blot analysis of TLR4, NF-κB p65, and phosphorylated p65 (P-p65) expression in arthrodial cartilage. All data are expressed as the mean ± SD (n = 6 per group). Post hoc ANOVA was used to test for statistical significance. ^∗p < 0.05, ^∗∗p < 0.01, and ^∗∗∗p < 0.001 versus the control group; ^#p < 0.05, ^##p < 0.01, and ^###p < 0.001 versus the DIO-KOA group.

Figure 4

Electroacupuncture increased the microbial diversity and altered the structure of the community of feces in obese rats. (a) Richness and diversity of the fecal microbiota. All data are expressed as the mean ± SD (n = 3 per group). Post hoc ANOVA was used to test for statistical significance. ^∗p < 0.05, ^∗∗p < 0.01, and ^∗∗∗p < 0.001 versus the control group; ^#p < 0.05, ^##p < 0.01, and ^###p < 0.001 versus the DIO-KOA group. (b) Principal coordinate analysis (PCoA) of the Bray-Curtis distance. (c) Cluster analysis of the unweighted pair group method with arithmetic mean (UPGMA) based on the Bray-Curtis distance.

Figure 5

Acupuncture-associated alterations in the fecal microbiota. (a) Comparison of the relative abundance of Firmicutes, Bacteroidetes, Proteobacteria, and Verrucomicrobia phyla within groups. (b) The ratio of Bacteroidetes/Firmicutes at the phylum level. All data are expressed as the mean ± SD (n = 3 per group). Post hoc ANOVA was used to test for statistical significance. ^∗p < 0.05, ^∗∗p < 0.01, and ^∗∗∗p < 0.001 versus the control group; ^#p < 0.05, ^##p < 0.01, and ^###p < 0.001 versus the DIO-KOA group. (c) The heat map of the top 50 abundant genera. Double hierarchical dendrogram shows the bacterial distribution.

Figure 6

Acupuncture-associated alterations at the genus level. All data are expressed as the mean ± SD (n = 3 per group). Post hoc ANOVA was used to test for statistical significance. ^∗p < 0.05, ^∗∗p < 0.01, and ^∗∗∗p < 0.001 versus the control group; ^#p < 0.05, ^##p < 0.01, and ^###p < 0.001 versus the DIO-KOA group.