Mechanism of electroacupuncture ameliorating colonic injury in mice with inflammatory bowel disease via the ILC3s/IL-22 pathway

To investigate the effects of electroacupuncture at "Zusanli" (ST36) on type 3 innate lymphoid cells (ILC3s) secreting interleukin (IL)-22 and intestinal cholinergic neurons in the colon of mice with inflammatory bowel disease (IBD), and to explore the mechanisms underlying electroacupuncture-mediated amelioration of IBD.

Twenty-four male C57BL/6J mice were divided into a normal group (n = 8) and a modeling group (n = 16) using the random number table method. The modeling group received 4% dextran sulfate sodium solution ad libitum for 7 days to establish the IBD model. On the fourth day after modeling, the modeling group was divided into a model group and an electroacupuncture group using the random number table method, with eight mice per group. Electroacupuncture intervention was applied bilaterally at "Zusanli" (ST36) in mice of the electroacupuncture group, once daily for 20 min each time, for seven consecutive days. After intervention, stool characteristics and occult blood were assessed. The disease activity index (DAI) of mice in each group was scored, and colon length was measured. The morphology of the colon tissue in mice was observed using hematoxylin-eosin staining, and the histopathological score was determined. A cytometric bead array was used to detect the contents of IL-1β, tumor necrosis factor-α (TNF-α), and IL-6 in colon tissue. Flow cytometry was used to determine the IL-22⁺ILC3s proportion in lamina propria lymphocytes of colon tissue. The content of IL-22 in colon tissue was detected using an enzyme-linked immunosorbent assay. Immunofluorescence was used to detect the number of choline acetyltransferase (ChAT)⁺/cellular Fos (c-Fos)⁺ co-labeled neurons in colon tissue.

Compared with the normal group, mice in the model group exhibited different degrees of loose stools, strongly positive fecal occult blood test, elevated DAI scores, shortened colon length, increased colon histopathological score; increased contents of IL-1β, TNF-α, and IL-6 in colon tissue; and a decreased IL-22⁺ILC3s proportion in lamina propria lymphocytes of colon tissue (P<0.05). Compared with the model group, mice in the electroacupuncture group exhibited improved fecal traits, weakly positive fecal occult blood test, decreased DAI score, increased colon length, reduced colon histopathological score; decreased contents of IL-1β, TNF-α, and IL-6 in colon tissues; an increased IL-22⁺ILC3s proportion in lamina propria lymphocytes of colon tissue; increased IL-22 content in colon tissue; and increased ChAT⁺/c-Fos⁺ co-labeled neurons in colon tissue (P<0.05).

Electroacupuncture at "Zusanli" (ST36) can significantly ameliorate colonic damage and reduce inflammatory responses in IBD mice, and its mechanism may be related to the activation of intestinal cholinergic neurons and the enhancement of colonic ILC3s function.