16S rRNA Gene Sequencing Combined with Metabolomics to Explore Intestinal Flora and Metabolic Changes in Young Febrile Rats and the Mechanism of Xiangqin Jiere Granules.

Purpose: Xiangqin Jiere Granules (XQJRG), a Chinese patent medicine used to treat acute fever in children caused by colds, seasonal flu, and coronavirus disease 2019 has been proven to have antipyretic and anti-inflammatory effects in young febrile rats. Fever is known to affect the host-gut microbiota crosstalk. However, the pharmacological mechanism of XQJRG in this regard remains unclear.

Methods: This study utilized a young febrile rat model previously reported by our team and extended the rat body temperature monitoring period following drug administration to explore the differences in efficacy between XQJRG and the commonly used pediatric antipyretic ibuprofen. Subsequently, the colonic contents of rats were analyzed using 16S rRNA gene sequencing and untargeted metabolomics. The short-chain fatty acid content was quantified using high-throughput targeted metabolomics. The expression of short-chain fatty acid receptors and pro-inflammatory genes in the colonic tissue was evaluated using quantitative real-time PCR, Western blot, and enzyme-linked immunosorbent assay.

Results: XQJRG showed a longer antipyretic duration than ibuprofen. XQJRG improved dysbiosis of the intestinal microbiota in young febrile rats, bringing its flora composition closer to that of normal rats. It significantly increased the relative abundance of and . related to the production of short-chain fatty acids (SCFAs), the contents of butyric acid and nonanoic acid and protein levels of SCFAs receptor GPR41. Moreover, XQJRG significantly increased the levels of metabolites with anti-inflammatory effects, reduced the contents of metabolites directly associated with fever, and decreased the levels of pro-inflammatory cytokines interleukin-1β and monocyte chemotactic protein-1 in the colon of young febrile rats to normal levels.

Conclusion: XQJRG exhibited a more stable and persistent antipyretic effect in young febrile rats compared to ibuprofen. Its mechanism was at least partially attributed to regulating intestinal flora disorders, increasing anti-inflammatory metabolites, and inhibiting the production of inflammatory factors in young febrile rats.