Oxymatrine alleviates NSAID-associated small bowel mucosal injury by regulating MIP-1/CCR1 signalling and gut microbiota.

Oxymatrine (OMT) as a quinazine alkaloid extracted from matrine has been shown to exhibit anti-inflammatory and anti-tumour effects. However, the protective mechanism of OMT on NSAID-associated small bowel mucosal injury remains unreported. We found that OMT could improve the clinical symptoms and pathological inflammation scoring, reduce the secretion of proinflammatory cytokines IL-1β, IL-6 and TNF-α and cell apoptosis, promote cell proliferation and protect intestinal mucosal barrier as compared with the Diclofenac Sodium (DS) group. Further RNA-seq and KEGG analysis uncovered that the differentially expressed genes between DS and control groups were mainly enriched in immune regulation, of which MIP-1γ and its receptor CCR1 expression were validated to be repressed by OMTH. MAPK/NF-κB as the MIP-1 upstream signalling was also inactivated by OMT treatment. In this study, OMT regulated gut microbiota. Venn diagrams visualized and identified 1163 shared OTUs between DS group and OMTH group. The results showed that the α diversity index in the DS group was lower than that in the OMTH group, indicating that the complexity of the flora was reduced in the intestinal inflammatory state. β diversity mainly includes Principal Component Analysis (PCA) and Principal Co-ordinates Analysis (PCoA). The differences between groups can be observed through PCA. The more similar the composition of the flora, the closer the samples are. We found that the difference was smaller in the DS group than in the OMTH group. The results of PcoA showed that the sample similarity between OMTH groups was the highest. Moreover, gut microbiota analysis unveiled that the abundances of Ruminococcus 1, Oscillibacter and Prevotellaceae at the genus level as well as Lactobacillus SP-L-Yj at the species level were increased in OMTH group as compared with the DS group but the abundance of Allobaculum, Ruminococceos-UCG-005, Ruminococceos-NK4A214 and Clostridium associated with DS-induced small bowel mucosal injury could be decreased by OMTH. MIP-1α and CCR1 were upregulated in human small bowel injury samples as compared with the normal ileal mucosa tissues. In conclusion, our findings demonstrated that OMT could alleviate NSAID-associated small bowel mucosal injury by inhibiting MIP-1γ/CCR1 signalling and regulating gut microbiota.