[Effects of electroacupuncture at on autophagy of colonic cells and gut microbiota in ulcerative colitis of rats].

OBJECTIVE

To observe the effects of electroacupuncture (EA) at (prescription for intestinal disease) on autophagy of colonic cells and gut microbiota in rats with ulcerative colitis (UC), and to explore the mechanism of EA in the treatment of UC.

METHODS

Thirty-two SD male rats were randomly divided into a control group, a model group, an EA group and a sham-EA group, with 8 rats in each group. Except the control group, the UC rat model was established by free drinking of 5% dextran sulfate sodium solution for 7 days in the other groups. In the EA group, was adopted, in which, EA was applied at "Tianshu" (ST25) and "Shangjuxu" (ST37), at disperse-dense wave and frequency of 10 Hz/50 Hz, for 20 min in each intervention. In the sham-EA group, shallow transcutaneous puncture was performed at the sites, 5 mm away from the points as the EA group, with the same parameters as the EA group. The intervention was delivered once daily for 3 consecutive days. The body weight was measured daily and the disease activity index (DAI) score was calculated before and after intervention. After intervention completion, the colon length was measured. Using HE staining, the colon morphology was observed and the score of colonic pathology was assessed. With ELISA adopted, the contents of tumor necrosis factor (TNF-α), interleukin (IL)-1β, IL-2 and IL-10 in the serum of the rats were detected. The ultrastructure of the colon tissue was observed under electron microscopy. Using Western blotting, the protein expression was detected for microtubule-associated protein 1 light chain 3 (LC3)Ⅱ, LC3Ⅰ, autophagy-related genes (ATG) 5, ATG12, sequestosome 1 (p62), phosphatidylinositol 3-kinase (PI3K), phosphorylated protein kinase B (p-AKT), protein kinase B (AKT), and phosphorylated mammalian target of rapamycin (p-mTOR), mammalian target of rapamycin (mTOR) in the colon tissue. The mRNA expression of PI3K, AKT and m-TOR in the colon tissue was detected by real-time fluorescence quantitative PCR. The 16S rRNA gene sequencing was used to analyze the structure of gut flora in the feces of rats.

RESULTS

From day 1 to day 7, compared with the control group, the body weight decreased in the model group, EA group, and SEA group (<0.05, <0.01). From day 9 to day 10, the EA group showed an increase in body weight compared with the model group and SEA group (<0.05, <0.01). Before intervention, the DAI score in the model group, EA group, and SEA group was higher than the score of the control group, respectively (<0.01). After intervention, the DAI score in the EA group was reduced compared with the model group and SEA group (<0.01). Compared with the control group, in the model group, the colon length of rats was shorter (<0.01); it showed the distorted crypts, thinner mucosal layer, reduced goblet cells, inflammatory cell infiltration and the disarranged histological structure; and the pathological score of the colon tissue increased (<0.01); the serum contents of TNF-α and IL-1β increased (<0.01), and those of IL-2 and IL-10 decreased (<0.01). The structure of colon epithelial cells was disarranged, with cilia pelt off, and a large number of vacuoles in the cytoplasm; the mitochondria were swollen, with unclear structure and cristae partially disappeared; and few autophagosomes were observed. The value of LC3Ⅱ/LC3Ⅰand the protein expression of ATG5 and ATG12 in the colon tissues were reduced (<0.01), the protein expression of p62 and PI3K, and the values of p-AKT/AKT, and p-mTOR/mTOR increased (<0.01), and mRNA expression of PI3K, AKT and mTOR was elevated (<0.01). The indexes of Chao1, Ace and Shannon decreased (<0.01). At the phylum level, the relative abundance of decreased (<0.05), that of and increased (<0.05, <0.01). At the genus level, the relevant abundance of decreased (<0.05), while that of _NK4A136_group and increased (<0.01, <0.05 ). Compared with the model group and SEA group, in the EA group, the colon length increased (<0.01), the infiltration of inflammatory cells was reduced, the arrangement of intestinal epithelial cells was arranged regularly, with a small amount of shedding, and the pathological score of the colon tissue decreased (<0.01). The serum contents of TNF-α and IL-1β decreased (<0.01), and those of IL-2 and IL-10 increased (<0.01). The colonic epithelial cells were arranged relatively, the morphology of organelles was basically normal, and autophagosomes were visible. The value of LC3Ⅱ/LC3Ⅰand the protein expression of ATG5 and ATG12 in colon tissue increased (<0.01, <0.05), the protein expression of p62 and PI3K, and the values of p-AKT/AKT, and p-mTOR/mTOR decreased (<0.01); and mRNA expression of PI3K, AKT, m-TOR was reduced (<0.01). The indexes of Chao1, Ace and Shannon increased (<0.01). At the phylum level, the relative abundance of increased (<0.01), while that of decreased (<0.01). At the genus level, the relative abundance of increased (<0.05), whereas that of _NK4A136_group decreased (<0.01). When compared with the model group, the relative abundance of decreased (<0.05), and that of was reduced (<0.05) in the EA group.

CONCLUSION

EA at alleviates UC symptoms probably through inhibiting the PI3K/AKT/mTOR signaling pathway to regulate colonic autophagy and improve the intestinal flora.