# Lactobacillus paragasseri LG‐1 Alleviates Urticaria‐Like Symptoms in Mice via Modulation of Gut Microbiota, Hypoxanthine and Uric Acid

## TL;DR

A specific Lactobacillus strain, LG-1, reduces urticaria symptoms in mice by lowering harmful metabolites and improving gut bacteria balance.

## Contribution

LG-1 is a novel probiotic that targets both gut microbiota and uric acid/hypoxanthine in chronic urticaria.

## Key findings

- LG-1 reduces serum uric acid and hypoxanthine in a mouse model of urticaria.
- LG-1 suppresses inflammation via the TLR4-NF-κB pathway.
- LG-1 promotes beneficial Lactobacillus and reduces harmful gut bacteria.

## Abstract

Chronic Spontaneous Urticaria (CSU) is an immunoinflammatory disorder with complex pathogenesis. Emerging evidence implicates that gut microbiota dysbiosis plays a pivotal role in this pathological network. Integrated 16S rRNA sequencing and untargeted metabolomics revealed distinct CSU‐associated signatures, including significant reductions in Lactobacillus abundance and elevated serum uric acid (UA) and hypoxanthine levels. Functional screening identified Lactobacillus paragasseri LG‐1 from breast milk as a potent purine‐metabolising strain, demonstrating significant hypoxanthine and UA degradation in vitro. In an ovalbumin (OVA)‐induced urticaria murine model, LG‐1 administration demonstrated marked reductions in serum UA and hypoxanthine concentrations, alleviated clinical manifestations, and suppressed inflammation via TLR4‐NF‐κB pathway inhibition. Moreover, it modulated gut microbial composition by promoting Lactobacillus proliferation while restraining pathogenic bacteria. These findings collectively established that LG‐1 exerted dual therapeutic effects through uric acid/hypoxanthine degradation and microbiome remodelling. Our study provides compelling evidence for microbiome‐targeted strategies in CSU management, highlighting LG‐1 as a promising therapeutic candidate.

Chronic Spontaneous Urticaria (CSU) is linked to gut dysbiosis and elevated serum uric acid/hypoxanthine. Lactobacillus paragasseri LG‐1 alleviates urticaria by degrading these metabolites, inhibiting TLR4‐NF‐κB inflammation, and remodelling gut microbiota.