Multi-omics chemical and biochemical profiling reveals ellagic acid enhances insulin sensitivity via gut microbiota-tryptophan-indole signaling mechanism.

Ellagic acid improved glucose tolerance and enhanced insulin sensitivity in the study model.

• Histology confirmed reduced lipid accumulation in liver, skeletal muscle, brown adipose tissue, and mesenteric fat following EA treatment.
• EA restored tissue architecture across these metabolically active tissues.
• EA is described as a dietary polyphenol with limited systemic bioavailability, resulting in substantial intestinal exposure.
• The study used multi-omics approaches including metagenomics, lipidomics, and transcriptomics to characterize mechanisms.

Metagenomic analysis showed EA enriched specific beneficial gut bacteria while reducing pathogenic species.

• EA enriched Akkermansia muciniphila, Muribaculum intestinale, and Duncaniella dubosii.
• EA reduced the abundance of Lachnoclostridium phocaeense.
• These microbial shifts were accompanied by elevated levels of tryptophan-derived metabolites.
• The analysis was performed using metagenomic sequencing of gut microbiota.

EA elevated tryptophan-derived indole metabolites known to enhance insulin sensitivity.

• Elevated metabolites included indole-3-propionic acid, indole, and indole-3-acrylic acid.
• These metabolites are described as 'known to enhance insulin sensitivity.'
• The microbial shifts induced by EA were specifically accompanied by these tryptophan-derived metabolite changes.
• The authors propose a gut microbiota-tryptophan-indole signaling mechanism as the primary pathway.

Lipidomic analysis revealed EA decreased triacylglycerols and ceramides while restoring phospholipid levels.

• EA decreased triacylglycerols and ceramides.
• EA restored phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine levels.
• These lipid changes are consistent with reduced lipid accumulation observed histologically.
• Lipidomics was one component of the multi-omics chemical and biochemical profiling approach.

Transcriptomic analysis revealed tissue-specific gene expression changes in liver, skeletal muscle, and adipose tissues following EA treatment.

• EA suppressed hepatic lipogenesis in liver tissue.
• EA inhibited MAPK signaling in skeletal muscle.
• EA activated thermogenic and oxidative phosphorylation pathways in adipose tissues.
• These transcriptomic findings were consistent with the histological and metabolic improvements observed.

The authors propose that EA alleviates insulin resistance through a gut microbiota-indole metabolite-multi-tissue axis.

• The proposed mechanism involves gut microbiota modulation leading to tryptophan-indole signaling.
• This signaling axis affects multiple tissues including liver, skeletal muscle, brown adipose tissue, and mesenteric fat.
• EA is described as having 'limited systemic bioavailability, resulting in substantial intestinal exposure,' supporting the primacy of the gut-mediated mechanism.
• The findings highlight EA as 'a food-derived polyphenol' that might act through this multi-tissue axis.