Electroacupuncture Attenuates Intestinal Barrier Disruption via the α7nAChR-Mediated HO-1/p38 MAPK/NF-κB Pathway in a Mouse Model of Metabolic Dysfunction-Associated Fatty Liver Disease: A Randomized, Single-Blind, Controlled Trial

Background: Gut barrier integrity plays a crucial role in the pathogenesis of metabolic dysfunction-associated fatty liver disease (MAFLD). Electroacupuncture (EA) at ST-36 can ameliorate inflammatory responses via stimulating the alpha 7 nicotinic acetylcholine receptor (alpha 7nAChR), but whether EA is effective in preserving the intestinal barrier of MAFLD has not been exactly illustrated. This investigation explored potential protection mechanisms of EA at ST-36 targeting the dismantled gut barrier in MAFLD. Methods: C57BL/6 mice were randomly allocated into several subgroups: control (CON), high-fat diet (HFD), HFD with EA, HFD with EA and alpha 7nAChR inhibitor alpha-BGT, and HFD with EA and intestinal HO-1 knockout (KO). Body weight, liver weight, visceral fat index, and histopathological examination of the liver and the intestine were determined. Serum biological indexes were evaluated through corresponding kits. Furthermore, the expressions of HO-1, alpha 7nAChR, gut barrier-associated proteins, and the molecular mechanisms in intestinal tissues were assessed via Western blot, RT-qPCR, immunohistology, or immunofluorescence examination. Results: EA treatment decreased body weight, liver weight, and visceral fat index gain and mitigated liver function injury and abnormal lipid indexes, exhibiting less severity of hepatic steatosis, fibrosis, and inflammation responses of MAFLD. Lower gut permeability, less intestinal epithelial disruption, and upregulation of tight junction proteins after EA suggested the protective effects in attenuating intestinal epithelial barrier dysfunction. These protective effects were abolished by alpha-BGT or intestinal HO-1 deletion. Mechanistically, EA markedly enriched alpha 7nAChR and HO-1 expression and mitigated phosphorylated p38 MAPK/NF-kappa B activation, which was lost in alpha-BGT or HO-1 KO treatment. Conclusions: The protective effects of EA at ST-36 in the pathogenesis of MAFLD may be attributed to the preserved intestinal barrier, thereby alleviating systemic inflammatory responses and preventing subsequent liver hits, where the alpha 7nAChR-mediated HO-1/p38 MAPK/NF-kappa B pathway was crucial to maintain homeostasis.