Metabolomics reveals immunomodulation as a possible mechanism for the antibiotic effect of Persicaria capitata (Buch.-Ham. ex D. Don) H.Gross.

Introduction: In spite of advances in antibiotics, urinary tract infection (UTI) is still among the most common reasons for antibiotic medication worldwide. Persicaria capitata (Buch.-Ham. ex D. Don) H.Gross ( P. capitata ) is a herbal medicine used by the Miao people in China to treat UTI. However studies of its mechanism are challenging, owing to the complexity of P. capitata with multiple constituents acting on multiple metabolic pathways.

Objective: The objective of this study was to explore the working mechanism of P. capitata on urinary tract infection.

Methods: Relinqing ® granule, which is solely made from aqueous extracts of the whole P. capitata plant, was used in this study. Urine metabolomics based on gas chromatography-mass spectroscopy was employed to assess the metabolic changes caused by administration of Relinqing® granule in a UTI mouse model. Female specific-pathogen-free Kunming mice were divided into control group (mock infection, saline treatment), model group ( E.coli infection, saline treatment), Relinqing® group ( E.coli infection, Relinqing® granule treatment), ciprofloxacin group ( E.coli infection, ciprofloxacin treatment), and sham- Relinqing® group (no surgery, Relinqing® granule treatment).

Results: The results showed that after the treatments, urine levels of itaconic acid in Relinqing® group increased by 4.9 fold and 11.3 fold compared with model and ciprofloxacin groups respectively. Itaconic acid is an endogenous antibacterial metabolite produced by macrophages, which also functions as a checkpoint for metabolic reprogramming of macrophage.

Conclusion: Our findings suggest that this herbal medicine can cure urinary tract infection through modulation of immune system.