Gynostemma pentaphyllum polysaccharides alleviate ulcerative colitis in mice via the Nrf2/ROS/NLRP3 axis and modulation of the gut microbiota.

Gynostemma pentaphyllum polysaccharides (GPP) were structurally characterized as bioactive macromolecules using integrated analytical methods.

• Comprehensive structural characterization was achieved through integrated chromatography coupled with NMR, FT-IR, and SEM analyses.
• GPP are identified as the primary bioactive macromolecules of Gynostemma pentaphyllum.
• Gynostemma pentaphyllum has a history of use in traditional Chinese medicine dating back over 500 years for heat-clearing and detoxification.

GPP alleviated UC symptoms in DSS-induced mouse models by suppressing inflammation, reducing oxidative stress, and improving gut barrier dysfunction.

• Efficacy was investigated in a DSS-induced UC mouse model and an LPS-stimulated Caco-2 cell inflammatory model.
• GPP treatment reduced markers of inflammation and oxidative stress in both in vivo and in vitro models.
• GPP improved intestinal barrier dysfunction as part of its therapeutic effects.

Nrf2 was identified as a key molecular target of GPP through transcriptomic analysis and database mining.

• RNAseq and GeneCards Human Gene Database analyses identified Nrf2 as a key target.
• GPP exerted anti-inflammatory and antioxidant effects via the Nrf2/HO-1 pathway.
• The efficacy of GPP was attenuated in Nrf2-/- mice, confirming Nrf2 dependency.
• Validation experiments were performed in Nrf2 knockout (Nrf2-/-) mice to confirm mechanistic findings.

GPP reduced ROS levels through Nrf2/HO-1 pathway activation, which subsequently inhibited NLRP3 inflammasome activation.

• The mechanistic axis identified was Nrf2/ROS/NLRP3.
• Activation of the Nrf2/HO-1 pathway by GPP led to downstream reduction of reactive oxygen species (ROS).
• Reduced ROS levels resulted in inhibition of NLRP3 inflammasome activation.
• This cascade collectively mitigated oxidative stress and inflammatory responses in UC.

GPP modulated gut microbiota composition by increasing Firmicutes abundance while decreasing Proteobacteria, re-establishing microbial homeostasis.

• 16S rRNA sequencing was used to assess gut microbiota changes following GPP treatment.
• GPP treatment increased the abundance of Firmicutes.
• GPP treatment decreased the abundance of Proteobacteria.
• These compositional shifts were associated with re-establishment of microbial homeostasis in UC mice.

GPP was identified as a promising macromolecule with translational potential for ulcerative colitis treatment.

• Findings collectively demonstrate GPP alleviates UC via multiple mechanisms including Nrf2/HO-1 pathway activation, ROS reduction, NLRP3 inhibition, and gut microbiota modulation.
• The study employed both in vitro (LPS-stimulated Caco-2 cells) and in vivo (DSS-induced UC mouse model, Nrf2-/- mice) experimental systems.
• The multi-modal protective effects support GPP's potential as a therapeutic agent for UC.