# Integrating network pharmacology, microbiomics, and metabolomics to uncover the therapeutic effect of Liubao tea on osteoarthritis

## TL;DR

Liubao tea may help treat osteoarthritis by changing gut bacteria and reducing harmful metabolic activity.

## Contribution

This study reveals Liubao tea's anti-osteoarthritis effects via gut microbiota modulation and pyrimidine metabolism inhibition.

## Key findings

- Liubao tea improved joint structure and reduced inflammation in osteoarthritis mouse models.
- Fecal microbiota transplantation from Liubao tea-treated mice replicated its therapeutic effects.
- Pyrimidine metabolism suppression was confirmed as a key mechanism in OA alleviation.

## Abstract

Osteoarthritis (OA) is a debilitating joint disorder for which with no effective disease-modifying drugs are currently available. Liubao tea, a traditional Chinese post-fermented tea, exhibits diverse bioactivities, including anti-inflammatory properties and the ability to regulate gut microbiota. However, its potential therapeutic efficacy and underlying mechanism in the context of OA remain insufficiently elucidated.

A mouse model of osteoarthritis (OA) induced by destabilization of the medial meniscus (DMM) was established, and the mice were treated with low- and high-dose Liubao tea extract. Micro-CT, histological staining (H&E, Safranin O-Fast Green), and enzyme-linked immunosorbent assay (ELISA) were performed to evaluate joint structure, cartilage damage, and inflammatory cytokine levels. 16S rRNA sequencing, fecal microbiota transplantation (FMT), and untargeted serum metabolomics were conducted to explore gut microbiota and metabolic changes. Additionally, Brequinar, a de novo pyrimidine synthesis inhibitor, was used to verify the role of pyrimidine metabolism. Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to analyze the chemical components of Liubao tea. Network pharmacology was employed to identify the active components and their potential targets in OA treatment. Molecular docking was performed to evaluate the interactions between key components and hub targets.

Liubao tea treatment significantly ameliorated DMM-induced OA progression, as evidenced by improved subchondral bone microarchitecture (increased bone volume/total volume [BV/TV], trabecular number [Tb.N], trabecular thickness [Tb.Th]; decreased trabecular separation [Tb.Sp]), the reduced cartilage erosion (lowered the modified Mankin and OARSI scores), and the suppressed systemic inflammation (decreased interleukin [IL]-6, IL-1β, tumor necrosis factor [TNF]-α levels). Liubao tea remodeled gut microbiota homeostasis (increased α-diversity and altered bacterial taxa), and fecal microbiota transplantation (FMT) from Liubao tea-treated mice recapitulated its anti-OA effects. Metabolomic analysis revealed that Liubao tea significantly downregulated the pyrimidine metabolism pathway, and Brequinar treatment mimicked its therapeutic benefits, confirming the role of pyrimidine metabolism suppression in OA alleviation. UPLC-MS/MS and network pharmacology analyses identified 1,989 metabolites in Liubao tea, including 273 bioactive components (e.g., flavonoids, lignans) that targeted 324 OA-related genes. The molecular docking results demonstrated that Eupatilin, 5,6,7,8-Tetramethoxyflavone, and 5-Hydroxy-6,7,3’,4’,5’-Pentamethoxyflavone exhibited potential interactions with the hub targets TP53, IL6, and TNF.

Liubao tea attenuates OA progression by modulating the composition of the gut microbiota and inhibiting the pyrimidine metabolism pathway, highlighting its potential as a novel natural therapeutic agent for OA.