Dihydroartemisinin alleviates dextran sulfate sodium-induced colitis in mice: Associations with gut microbiota, arachidonic acid metabolism, and the IL-17 signaling pathway.

BACKGROUND: Dihydroartemisinin (DHA), a sesquiterpene lactone derived from artemisinin, exhibits well-documented anti-inflammatory and anti-cancer properties. However, the precise mechanisms through which DHA alleviates ulcerative colitis (UC) remain incompletely understood.

PURPOSE: This study aimed to investigate the effects and underlying mechanisms of DHA on dextran sulfate sodium (DSS)-induced colitis in mice using a multi-omics approach, including 16S rRNA microbiomics, non-targeted and targeted metabolomics, RNA-seq transcriptomics and network pharmacology analysis.

METHODS: A DSS-induced murine colitis model was established and treated with DHA. Disease activity, colonic pathology, and intestinal barrier function were assessed. Gut microbiota composition was analyzed via 16S rRNA sequencing, while colonic metabolites were profiled using non-targeted metabolomics. Key signaling pathways associated with DHA treatment were predicted through RNA-seq and network pharmacology, and further validated by qRT-PCR and flow cytometry. Antibiotic depletion experiments were performed to evaluate the role of the gut microbiota. Intestinal barrier integrity was examined by immunofluorescence, western blot, and AB/PAS staining. Targeted metabolomic analysis of specific colonic metabolites was conducted using the Q300 kit.

RESULTS: DHA treatment significantly ameliorated colitis symptoms, as indicated by reduced body weight loss, lower disease activity index (DAI) scores, attenuated colon shortening, and improved histopathology. DHA treatment correlated with restored intestinal barrier function including increased goblet cell numbers, enhanced mucin-2 expression, and upregulating tight junction proteins. It was also associated with mitigated gut microbiota dysbiosis, notably including restored abundance of Bifidobacterium and suppressed opportunistic pathogens. Non-targeted metabolomics revealed that DHA treatment was associated with significant changes in arachidonic acid metabolism. Integrated transcriptomics and network pharmacology analysis indicated that DHA treatment was correlated with suppression of the IL-17 signaling pathway and restoration of Th17/Treg balance in colonic tissues. Crucially, the therapeutic benefits of DHA were abolished in microbiota-depleted mice, manifested as loss of mucosal protection, absence of IL-17 pathway and Th17/Treg balance modulation, and no significant alteration in arachidonic acid levels as detected by targeted metabolomics.

CONCLUSION: Our findings highlight the multifaceted therapeutic potential of DHA in colitis treatment, and suggest that the gut microbiota is associated with its protective effects. The beneficial effects observed with DHA treatment are correlated with preservation of intestinal barrier integrity, restoration of microbial homeostasis, changes in arachidonic acid metabolism, and modulation of the IL-17 pathway and Th17/Treg balance. These insights provide promising directions for novel UC therapeutic strategies.