Gastrodin ameliorates ulcerative colitis via modulating gut microbial tryptophan metabolism and AhR/NLRP3 pathway

Ulcerative colitis (UC), a chronic idiopathic inflammatory bowel disorder, presents persistent therapeutic challenges in clinical management. Gastrodin (GAS) is an active compound isolated from traditional Chinese medicine Gastrodia elata (Tianma), exhibits robust anti-inflammatory bioactivity. However, the role of GAS in UC has not been thoroughly studied.

The study aimed to investigate the protective effect of GAS against UC induced by DSS and its underlying mechanisms, with a particular emphasis on gut microbiota-metabolite interactions.

The ameliorative effect of GAS on UC was examined, followed by 16S rRNA sequencing, targeted metabolomics, MALDI-MSI analysis, and western blotting analysis, fecal microbiota transplantation (FMT) to investigate the underlying mechanism of GAS on UC.

Evaluation of symptoms showed that GAS exhibited dose-dependent beneficial effects on UC. Targeted metabolites showed that GAS increased the production of tryptophan-derived metabolites, including kynurenic acid (Kyna), indole-3-acetic acid (IAA), indole-3-carboxaldehyde (IAld), and indole-3-lactic acid (ILA), etc. MALDI-MSI confirmed that GAS increased the levels of aryl hydrocarbon receptor (AhR) ligands IAld and IAA in the colon tissue. Western blotting showed that GAS mitigated colon inflammation through the activation of the AhR/NOD-like receptor protein 3 (NLRP3) pathway. Finally, FMT confirmed that GAS ameliorates UC in a microbiota-dependent manner and the involvement of gut microbiota derived AhR ligands and AhR/NLRP3 pathway.

GAS alleviates UC via modulating gut microbiota-derived tryptophan metabolites (Kyna, IAA, IAld, ILA) in a microbiota-dependent manner and suppressing AhR/NLRP3 pathway. Our study has important practical implications for the application of traditional Chinese medicine-derived active ingredients in the treatment of UC.