Aim
To investigate the mechanism of electroacupuncture (EA) and herb-partitioned moxibustion (HM) on UC rats by using proteomics technology.
Background
Ulcerative colitis (UC) is a chronic, nonspecific intestinal inflammatory disease. Acupuncture and moxibustion is proved effective in treating UC, but the mechanism has not been clarified. Proteomic technology has revealed a variety of biological markers related to immunity and inflammation in UC, which provide new insights and directions for the study of mechanism of acupuncture and moxibustion treatment of UC.
Conclusion
EA and HM could regulate the expression of ATP5L, Atp5f1, Cox4i1 that associated with oxidative phosphorylation, then might regulate immune-related pathways of intestinal immune network for IgA production, FcγR-mediated phagocytosis, thereby alleviating colonic inflammation of DSS-induced UC rats.
Methods
Male Sprague-Dawley rats were randomly divided into the normal (N) group, the dextran sulfate sodium (DSS)-induced UC model (M) group, the HM group, and the EA group. UC rat model was prepared with 3% DSS, and HM and EA interventions at the bilateral Tianshu and Qihai acupoints were performed in HM or EA group. Haematoxylin and eosin staining was used for morphological evaluation of colon tissues. Isotope-labeled relative and absolute quantification (iTRAQ) and liquid chromatography-tandem mass spectrometry were performed for proteome analysis of the colon tissues, followed by bioinformatics analysis and protein-protein interaction networks establishment of differentially expressed proteins (DEPs) between groups. Then western blot was used for verification of selected DEPs.
Results
The macroscopic colon injury scores and histopathology scores in the HM and EA groups were significantly decreased compared to the rats in the M group (P < 0.01). Compared with the N group, a total of 202 DEPs were identified in the M group, including 111 up-regulated proteins and 91 down-regulated proteins, of which 25 and 15 proteins were reversed after HM and EA interventions, respectively. The DEPs were involved in various biological processes such as biological regulation, immune system progression and in multiple pathways including natural killer cell mediated cytotoxicity, intestinal immune network for immunoglobulin A (IgA) production, and FcγR-mediated phagocytosis. The Kyoto Encyclopedia of Genes and Genomes pathways of DEPs between HM and M groups, EA and M groups both included immune-associated and oxidative phosphorylation. Network analysis revealed that multiple pathways for the DEPs of each group were involved in protein-protein interactions, and the expression of oxidative phosphorylation pathway-related proteins, including ATP synthase subunit g (ATP5L), ATP synthase beta subunit precursor (Atp5f), cytochrome c oxidase subunit 4 isoform 1 (Cox4i1) were down-regulated after HM and EA interventions. Subsequent verification of selected DEPs (Synaptic vesicle glycoprotein 2A; nuclear cap binding protein subunit 1; carbamoyl phosphate synthetase 1; Cox4i1; ATP synthase subunit b, Atp5f1; doublecortin like kinase 3) by western blot confirmed the reliability of the iTRAQ data, HM and EA interventions can significantly down-regulate the expression of oxidative phosphorylation-associated proteins (Cox4i1, Atp5f1) (P < 0.01).