Polygonatum sibiricum polysaccharide ameliorates intestinal barrier dysfunction in aging mice via gut microbiota-metabolite modulation and TLR4/NF-κB pathway inhibition.

BACKGROUND

Intestinal barrier dysfunction is a critical pathological feature of aging-related diseases. Polygonatum sibiricum polysaccharide (PSP), a natural bioactive compound, has been reported to possess microbiota-regulatory and immunomodulatory properties; however, its protective effects against aging-induced intestinal barrier injury and the underlying mechanisms remain unclear.

PURPOSE: This study aimed to investigate the protective effects of PSP on age-related intestinal barrier dysfunction and to elucidate the underlying mechanisms, with a particular focus on the microbiota-metabolism-immunity axis.

STUDY

DESIGN

A combination of in vivo and in vitro experiments, together with multi-omics analyses and network pharmacology, was employed to systematically evaluate the effects and mechanisms of PSP in aging-associated intestinal barrier injury.

METHODS

Ultraviolet (UV) spectroscopy, gel permeation chromatography (GPC), high-performance liquid chromatography-mass spectrometry (HPLC-MS), and Fourier-transform infrared spectroscopy (FT-IR) were adopted to comprehensively characterize the purity and detailed structural profiles of PSP. Naturally aged mice were orally administered PSP (400 mg/kg) to assess intestinal barrier integrity, permeability, inflammatory responses, and gut microbiota composition. In vitro, D-galactose (D-gal)-induced senescent Caco-2 cells were treated with PSP (100, 200, and 400 μg/ml) to evaluate cellular senescence, tight junction protein expression, and pro-inflammatory cytokine production. Network pharmacology analysis was conducted to predict key signaling pathways involved, followed by experimental validation and reverse confirmation using a TLR4 agonist.

RESULTS

Characterization by UV spectroscopy and GPC confirmed the purity and molecular weight distribution of PSP, respectively; monosaccharide analysis revealed it was mainly composed of glucose, mannose, and galactose, and FT-IR identified its characteristic functional groups. In naturally aged mice, PSP administration significantly improved intestinal barrier integrity, reduced intestinal permeability, alleviated inflammatory responses, and reshaped gut microbiota composition. In Caco-2 cells, PSP dose-dependently attenuated D-gal-induced cellular senescence, restored tight junction protein expression, and suppressed pro-inflammatory cytokine production. Network pharmacology analysis identified the TLR4/NF-κB signaling pathway as a potential key target of PSP, which was further confirmed by both in vivo and in vitro experiments.

CONCLUSIONS

Collectively, these findings demonstrate that PSP alleviates aging-associated intestinal barrier dysfunction through multi-level regulation involving the microbiota-metabolism-immunity axis and supports its potential as a natural therapeutic candidate for anti-aging interventions.